Dysfunction in Ca2+ regulation results in an inability to sustain insulin secretion. This review defines the functions, structure, and mutations associated with the MCU complex members mitochondrial calcium uniporter protein (MCU), essential MCU regulator (EMRE), mitochondrial calcium uptake 1 (MICU1), mitochondrial calcium uptake 2 (MICU2), and mitochondrial calcium uptake 3 (MICU3) in the pancreatic β-cell. This review provides a framework for further evaluation of the MCU complex in β-cell function and insulin secretion.The Mitochondrial Calcium Uniporter Complex (MCU Complex) is essential for β-cell function due to its role in sustaining insulin secretion. The MCU complex regulates mitochondrial Ca Pancreatic endocrine hormones regulate systemic metabolism and are essential to preserving blood glucose homeostasis. These hormones are produced by groups of endocrine cells found in pancreatic islets of Langerhans. The islets are composed of alpha, beta, gamma, delta, and epsilon cells which secrete their specific hormone in response to various signals. The pancreatic endocrine hormones include pancreatic polypeptide, somatostatin, ghrelin, glucagon, and insulin . The panATP channels at the cell membrane [ATP channel closure alters the cell membrane electrochemical gradient, which stimulates the L-type Ca2+ channels and allows Ca2+ influx to the cytosol from the extracellular environment. Ca2+ is also released to the cytosol from the smooth endoplasmic reticulum, further increasing cytosolic Ca2+ concentration [Mature insulin is formed in the β-cell and prepared for exocytosis. Each insulin granule contains roughly 250,000 molecules of insulin and has a diameter of 250 nm . The matmembrane . The KATntration . 2+ entry through pancreatic β-cell membrane voltage-gated L-type Ca2+ channels triggers insulin granule exocytosis and is required for the postprandial spike in insulin secretion [2+ influx to the cytosol also stimulates metabolic enzymes which increase ATP production [2+ to the mitochondria, through the MCU complex, to perpetuate insulin secretion [Caecretion . Ca2+ inoduction . The iniecretion . This wi2+ concentration is similar to the cytosolic Ca2+ concentration. Following the closure of the plasma membrane voltage-gated L-type K+ channels cytosolic Ca2+ concentration rises significantly, stimulates insulin secretion, and begins to diffuse into the mitochondrial matrix through the Mitochondrial Calcium Uniporter (MCU) complex. The MCU complex tightly regulates the influx of mitochondrial Ca2+ to prevent apoptosis [2+ concentration in the mitochondrial matrix further increases ATP synthase activity. ATP is transported to the cell membrane to ensure the closure of the L-type voltage-gated K+ channels and to provide for continued Ca2+ influx to the cytosol. The continued Ca2+ influx allows for sustained GSIS [During resting conditions, the β-cell mitochondrial Capoptosis . Increasned GSIS . 2+ concentrations and regulate mitochondrial Ca2+ uptake. The tight regulation of mitochondrial and cytoplasmic Ca2+ concentrations maintain insulin secretion. These proteins are the mitochondrial calcium uniporter (MCU), mitochondrial calcium uptake 1 (MICU1), mitochondrial calcium uptake 2 (MICU2), mitochondrial calcium uptake 3 (MICU3), and the essential MCU regulator (EMRE) [2+ levels and MICU1 opens the MCU to allow mitochondrial Ca2+ influx, MICU2 has an inhibitory effect on the MCU complex under low cytoplasmic Ca2+ conditions    [2+ concentration. The highly negative electrochemical potential is due to the electron transport chain pumping hydrogen ions into the intermembrane space [2+ concentrations and mitochondrial matrix Ca2+ concentrations. Rizzuto et al. examined the effect of agonist driven changes in Ca2+ concentration. They showed that increased cytosolic Ca2+ concentration will inevitably lead to increased mitochondrial matrix Ca2+ concentration. However, in the presence of uncoupling proteins in the inner mitochondrial membrane, there is no net diffusion of Ca2+ into the mitochondrial matrix [Ca−180 mV) ,14, and ne space . Severall matrix .2+ influx has the potential to induce β-cell GSIS or apoptosis. The subsequent mitochondrial signals differ due to the polyphosphate molecules located in the mitochondrial matrix [2+ sink due to these polyphosphate molecules [2+ levels without signaling for apoptosis [2+ regulation, and studies are needed to examine the relationship between these two methods of altering mitochondrial Ca2+ flux. Cellular Cal matrix . The mitolecules . Experimpoptosis . The MCU2+ influx regulates mitochondrial fuel metabolism. Increased matrix Ca2+ levels directly stimulate pyruvate dehydrogenase phosphatase [2+ levels increase electron transport chain (ETC) activity. Rutter et al. showed that increased matrix Ca2+ specifically stimulated ETC complexes I, III, and IV. Stimulation resulted in greater conductance and fuel transport [2+ concentration results in increased ATP production and sustained cell membrane voltage-gated potassium channel closure [2+ concentration results in the formation of calcium phosphate molecules. Calcium phosphate decreases the activity of ATP synthase activity by blocking the interaction between ETC complex I and NADH [Mitochondrial matrix Casphatase , isocitrsphatase . Other sransport . Increas closure . These e closure . Excess and NADH . 2+ ATPase (SERCA) pumps provide the majority of mitochondrial Ca2+ efflux [2+ needs in the mitochondria. NCLX activity is regulated by concentration gradients across the inner mitochondrial membrane [2+ concentration is higher in the mitochondrial matrix, in pancreatic β-cells, following glucose stimulation. The increased matrix Ca2+ concentration causes increased ATP production and is needed for insulin secretion. NCLX activity following insulin secretion utilizes the sodium and Ca2+ concentration gradients to pump Ca2+ out of the cell and restore basal inner mitochondrial membrane resting potential [2+ out of the matrix will prepare the cell for future GSIS. The sodium calcium exchanger (NCLX), and sarcoplasmic reticulum/endoplasmic reticulum Ca+ efflux . NCLX anmembrane . Sodium otential ,25. Pump2+. Mitochondrial Ca2+ influx can lead to either apoptosis or GSIS. Mitochondrial membrane permeability transition pore (PTP) opening allows for rapid Ca2+ release from the mitochondria into the cytosol. When the PTP is constitutively open mitochondrial metabolism decreases, the mitochondrial membrane ruptures, and apoptogenic proteins are released from the mitochondria [2+ release into the cytosol. RER Ca2+ release into the cytoplasm in conjunction with PTP opening results in cellular apoptosis [Cellular signals for apoptosis utilize increased mitochondrial matrix Cachondria ,27. Duripoptosis ,25. 2+ influx into the mitochondrial matrix. In the β-cell, this is essential for maintaining GSIS [2+ diffuses to enter the mitochondria  or to a known inhibitor (mitoxantrone). Kaempferol exposure resulted in increased mitochondrial Caexposure . These dexposure ,33,34. T2+ channel that is necessary for first and second phase β-cell insulin secretion. MCU protein knockout blocks Ca2+ transfer to the mitochondrial matrix. Knockout of the MCU protein results in decreased Ca2+ dependent activity of the electron transport chain and ATP synthase, and ultimately reduces cellular ATP levels [ATP channels [2+ flux in T2D patients, and MCU activation may help alleviate T2D symptoms [The MCU protein is a mitochondrial CaP levels ,40. β-cechannels ,41. Theschannels . The MCUsymptoms . 2+ entry due to channel size and protein structure. The MCU protein is Ca2+ inwardly rectifying, due to Ca2+ binding site specificity. These binding sites have an extremely high affinity for Ca2+ (dissociation constant less than 2 nM) which causes the MCU protein to exhibit Ca2+ sensitivity even at extremely low cytoplasmic Ca2+ concentrations [2+ binding site specificity prevents MCU protein activation by any other ion. The MCU operates independently and is not coupled to the transport of any other ion [2+ concentration following cellular glucose uptake and metabolism results in a Ca2+ concentration gradient between the cytoplasm and the mitochondrial matrix. This gradient drives the selective Ca2+ diffusion into the mitochondrial matrix by way of the MCU protein [The MCU protein is specific for Catrations . The MCUther ion . In the  protein .2+ efflux, leading to ROS formation in β-cells. Palmitate induces a positive feedback loop with ER Ca2+ depletion and ROS generation that leads to cell death [2+ sink and prevents mitochondrial ROS generation, which is induced by greater fatty acid metabolism [Palmitate induces endoplasmic reticulum (ER) Call death ,47. Expotabolism ,49. Palm+ channels have a regulatory role on MCU function. Mouse islets were used to clarify the relationship between the two regulatory channels. It was already known that MCU protein knockout is associated with increased mitochondrial fragmentation, decreased oxidative phosphorylation, impaired glycolysis, and impaired proliferation [+ channel knockout, and the cells were unable to sustain insulin secretion. Cytosolic Na+ influx activates the MCU and allows for increased mitochondrial Ca2+ influx. Na+ then exits the mitochondria via NCLX [2+, further increasing mitochondrial Ca2+ concentration and aiding in GSIS. β-cell Naferation . Researcvia NCLX , and is 2+ specificity is determined through two acidic rings along the central axis of the Ca2+ pore [2+ specificity [The MCU is a 40 kilodalton protein located in the inner mitochondrial membrane . The MCUa2+ pore . Chanel cificity .2+ specificity and MCU function. When a mutant MCU expresses only one helix, Ca2+ uptake is terminated. Single nucleotide polymorphisms (SNPs) resulting in bulky side chains disrupt the helix structure and also cause a lack of function. These results show the essential role of the transmembrane helices in Ca2+ transport across the inner mitochondrial membrane [The MCU transmembrane helices are essential for Camembrane . The losmembrane .MCU gene is on human chromosome 10 [The osome 10 . The MCUosome 10 . 2+ levels [2+ concentrations, MICU1 closes the MCU by binding to the MCU acidic aspartate residues in the intermembrane space to close the MCU pore. MICU1 contains arginine finger motifs that bind with the MCU aspartate rings to ensure MCU complex closure  functions as a regulatory subunit in the MCU complex. MICU1 is required to preserve normal mitochondrial Ca+ levels . During  closure . Closingl matrix . This phl matrix ,59,60,612+ levels rise, such as following β-cell glucose uptake, Ca2+ diffuses through the outer mitochondrial membrane and interacts with MICU1 and the MCU. Ca2+ binds the MCU aspartate rings, resulting in the dissociation of MICU1 from MCU [2+ to flow into the mitochondrial matrix, which stimulates ATP production and ultimately leads to sustained GSIS in the β-cell [2+ uptake. This impaired Ca2+ uptake resulted in structural changes including forming short tubular mitochondria. MICU1 knockout was not rescued by increased expression of MCU [When cytosolic Cafrom MCU . MICU1 de β-cell . MICU1 kn of MCU ,37,62,632+ influx. MICU1 deletion in HeLa cell lines leads to rapid apoptosis due to excessive mitochondrial matrix Ca2+ influx. MICU1 knockout removes the primary gatekeeper protein on the MCU and unregulated mitochondrial Ca2+ influx causes apoptosis [MICU1 also has a regulatory role in preventing excessive mitochondrial matrix Capoptosis . The maj2+ conditions. This heterodimer then binds to the surface of the MCU and prevents Ca2+ diffusion into the mitochondrial matrix [MICU1 is a 54 kilodalton protein that is made up of 476 amino acids. MICU1 is connected to the MCU complex via EMRE. EMRE spans the inner mitochondrial membrane and extends into the intermembrane space to anchor MICU1 to the protein complex . MICU1 fl matrix . MICU1 gene is located on human chromosome 10 in close proximity to the MCU gene [The MCU gene . ExpressMCU gene ,65. 2+ sensing in conjunction with MICU1. β-cell siRNA mediated MICU2 knockdown attenuates GSIS by 41–51 percent [2+ uptake is attenuated, the ETC is not stimulated, and ATP is not transported to the cell membrane to close the K+ channels. These data indicate that MICU2 is essential for sustained GSIS in the pancreatic β-cell. MICU2 deletion results in Ca2+ accumulation in the submembrane compartment in the mitochondrial matrix of the β-cell [MICU2 forms a disulfide bond with MICU1 and is involved in Ca percent . Similare β-cell .2+ regulation in the β-cell. In β-cell MICU2 knockout mice GSIS was inhibited by 57%, and there was decreased activity at the cell membrane Ca2+ channels. There is currently no known mechanism for the decreased cytosolic Ca2+ levels associated with MICU2 knockout. There is also an unknown mechanism by which MICU2 knockout mice were able to sustain euglycemia with decreased insulin secretion. There was also an accumulation of insulin within the mouse β-cells. Defining the mechanism by which MICU2 knockout impairs cytosolic β-cell Ca2+ levels is imperative.MICU2 also plays a role in cytosolic Ca2+ levels are elevated, Ca2+ binds to MICU2 and removes the inhibitory effect on the MCU complex [2+ influx. Conversely, when cytosolic Ca2+ levels are decreased, MICU2 binds to MICU1 and causes blockage of the MCU protein-mediated Ca2+ influx. When MICU1 is silenced in rodent models MICU2 activity overexpression does not rescue the MICU1-mediated mitochondrial deficiency [2+ uptake is attenuated [2+ sensor [MICU1 and MICU2 have complementary roles. When cytosolic Ca complex . This caficiency . Similartenuated . Knockou+ sensor ,67. Both+ sensor .2+ influx to the mitochondrial matrix in the β-cell [2+ flux in β-cells. MICU1 and MICU2 function in conjunction to regulate Cae β-cell . Most ofMICU2 gene is located on chromosome 13. Though this gene is on a different chromosome than MICU1 there is a positive linear relationship between the expression of MICU1 and MICU2 expression [MICU2 expression varies based on the tissue type. MICU2 localizes exclusively to mitochondria. Though MICU2 is found throughout the body, expression is highest in the visceral organs . The MICpression . This su2+ uptake via the MCU [2+ concentration [MICU3 is an EF hand containing protein that forms a disulfide bond with MICU1 and has no association with MICU2. MICU3 functions as an enhancer of mitochondrial Ca the MCU  (Figure ntration . In this2+ overload in the mitochondria [2+ influx and prevented cardiac apoptosis in rodents. Though these data pertain to heart function, this same mechanism induces apoptosis in pancreatic β-cells [MICU3 assists in cell-mediated apoptosis. MICU3 silencing in vivo conferred cardioprotective effects in mice with induced cardiac dysfunction. Induced cardiac dysfunction normally results in apoptosis via Cachondria . MICU3 k β-cells . FurtherMICU3 gene is located on chromosome 8 [MICU3 is localized to the outer leaflet of the mitochondrial inner membrane and is expressed throughout the body. The highest concentrations of MICU3 are found in the brain and skeletal muscle . The MICmosome 8 .2+ sensing [2+ and change the EMRE protein conformation according to Ca2+ concentration variations (2+ exceeds levels needed for cellular function Ca2+ binds to the acidic residues, an EMRE conformational change is induced and the MCU complex is closed. Low matrix Ca2+ concentration following periods of MCU closure causes Ca2+ to dissociate from the acidic residues of the EMRE N-terminal tail. Ca2+ dissociation results in a conformation change to EMRE that opens the MCU complex from the matrix side [2+ conditions and high matrix Ca2+ conditions via EMRE mediated Ca2+ sensing. This research was performed in human embryonic kidney cell lines, though this same conformational change is anticipated to occur in β-cells. The essential MCU regulator protein, EMRE, is a 10-kilodalton transmembrane protein. This protein is located in the inner mitochondrial matrix and is essential for matrix Ca sensing ,74. EMREriations . When marix side . Therefo2+ via MCU following cellular glucose uptake [2+ release from the endoplasmic reticulum. MICU1 exerts an excitatory effect on the MCU leading to Ca2+ uptake and GSIS [EMRE post translational modifications, such as phosphorylation of serine residues S57 and S92, determine MCU localization in the mitochondrial membrane . β-cell e uptake . Glucoseand GSIS . EMRE poand GSIS . This poSMDT1 gene, which codes for EMRE, is located on chromosome 22 [EMRE spans the inner mitochondrial membrane in many cell types throughout the human body. Expression does not vary significantly according to tissue type. The osome 22 . The MCU complex is essential for sustained insulin secretion, though there are mutations in this complex that result in disease states. There are identified disease states for MCU protein, MICU1, and EMRE. There are currently no disease states identified for MICU2 and MICU3, suggesting the need for further research into these proteins. There is also a possibility that mutations in MICU2 and MICU3 result in spontaneous abortion. 2+ uptake. Though mice lacking the MCU protein are viable they are unable to increase mitochondrial metabolism in response to cellular signals [Mice lacking the MCU protein are viable, though there is an increase in embryonic spontaneous abortion. MCU knockout was also hypothesized to decrease apoptosis, however, mice models are inconclusive . These m signals ,78. 2+ overload and cell death [Mutations in the inner mitochondrial membrane proteases result in altered MCU protein function. The mitochondrial protease m-AAA will degrade the MCU regulatory subunit EMRE when mutated. Protease m-AAA stimulated EMRE degradation results in constitutively active MCU channels facilitating Call death . MCU knoll death ,80,81. Homozygous deletion of a 2755 base pair segment of exon 1 of MICU1 results in total deletion of the MICU1 protein. This mutation was observed in 2 human patients, who were tested for MICU1 function following an appointment with a physician. These patients presented with fatigue, migraine, and increased creatine kinase levels. The patients had decreased pyruvate dehydrogenase activity and were able to secrete low levels of insulin .2+ handling. The phenotype consists of proximal myopathy, learning disabilities, and an extrapyramidal learning disorder [MICU1 loss of function mutation also presented as myopathy with extrapyramidal signs. This condition is characterized by abnormal Cadisorder . 2+ flux was measured. These cells had increased mitochondrial Ca2+ flux as compared to control cells [A MICU2 truncation mutation was recently discovered in patients presenting with a severe neurological disorder and cognitive impairment. Samples were taken from patients and mitochondrial Caol cells . 2+ to stimulate the mitochondria and there is a very high rate of spontaneous abortion. Knockout mice are born at one-fifth the rate predicted by Mendelian genetics [There are no known EMRE mutations in humans. The highly conserved nature of this protein is indicative of essential function. Interestingly, EMRE knockout mice are viable. Though these mice are viable they cannot utilize Cagenetics . A summa2+ concentrations, which causes Ca2+ to enter the intermembrane space and bind to MICU1 [2+ to flow into the mitochondria down its concentration gradient [2+ conditions [2+ in the matrix [2+ levels are sufficient to sustain insulin secretion EMRE causes MICU1 to close the MCU channel and prevent excessive Ca2+ accumulation [2+ activates MICU2, which causes a MICU1-MICU2 heterodimer to close the MCU channel and stop Ca2+ flow into the mitochondrial matrix [2+ sensing role in addition to providing the channel for Ca2+ to diffuse down. The MCU complex facilitates insulin secretion by increasing the flux of Ca2+ into the mitochondrial matrix. The MCU complex is essential for sustained GSIS in the pancreatic β-cell ,7,86,87.to MICU1 . MICU1 agradient . EMRE spnditions ,75. EMREl matrix ,66. Each2+ flux in β-cells. Finally, it is of extreme importance to understand how the MCU complex functions under various physiological states. Therefore, studies that explore the function of the wild type or mutant MCU complex components during diet-induced obesity, aging, pregnancy, and T2D are needed. The completion of these studies will better define how the MCU complex may impinge on β-cell associated pathologies observed in these different physiological states. This review provides a framework for further studies to investigate MCU function in β-cells in various disease states, such as diabetes mellitus. These studies demonstrate the importance of the MCU in maintaining the ability of the β-cell to dynamically respond to elevated blood glucose through the propagation of insulin secretion. Given the effects of MCU component deletion and mutations on β-cell insulin secretion, these data suggest that the MCU complex may be pharmacologically targetable to modulate insulin secretion in patients with T2D. While much is currently known about various components in the β-cell, additional studies are needed to fully explore the role of this complex and its components in maintaining and improving functional β-cell mass. While studies have been completed that help to define the role of MCU, MICU1, and MICU2 in the β-cell, targeted studies on MICU3 and EMRE in the β-cell are still needed. These targeted studies on MICU3 and EMRE should include β-cell specific knock-out studies. In addition, the effects of naturally occurring MICU3 and EMRE mutations should be explored. The potential anti-apoptotic effects of MICU3 need to be explored to define a mechanism of action. Further research is also needed to understand the regulatory role of MICU2 on mitochondrial Ca


Myelodysplastic syndromes (MDSs) have a 5-year transformation risk to AML of 20%. These cases are also associated with poor outcomes. Hence, this highlights the importance of uncovering the underlying triggers and pathophysiology of this progression to find ways to hinder this process. In addition, both conditions should be distinguished clearly to maximize the benefit of treatment.Wong et.al investigated the effect of hypomethylating agents (HMAs), specifically decitabine and guadecitabine, in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). They discussed the role of HMAs in increasing the expression of cancer/testis antigens (CTAs), which are a subgroup of tumor-associated antigens (TAAs), in tumors. CTAs increase immune responses when they are expressed outside their usual locations in immune-privileged organs. This leads to an increased antileukemic response in MDS and AML. The CTA NY-ESO-1 is one of the most studied CTAs and is highly increased in those tumors. When this method is combined with cancer vaccines, which utilize immunologic activity against CTAs, the immunogenicity and response would be stronger and more effective since more antigen presentation would be present on tumor cells. Evidence has shown that adding guadecitabine to vaccines may increase the capability of cytotoxic T-cells (CTLs) to kill tumor cells. There is also evidence that combining HMAs with immune checkpoint inhibitors, such as programmed cell death (PD-1)/programmed death ligand-1 (PDL-1) inhibitors, enhances the response to therapy as it may overcome resistance. Low-dose decitabine was also shown to trigger natural killer (NK) cell response against AML antigens. This still requires further studies as well as clinical trials to confirm the predicted effects of HMAs on AML and MDS patients.Joudinaud and Boyer investigated the mechanisms causing the progression of MDSs to AML. The origins of these cells were also discussed. They showed that MDS cells are derived from hematopoietic stem cells that may acquire genetic aberrations. Leukemic stem cells, on the other hand, are derived from progenitor cells. The review demonstrates the rise in CD123 and CLL1 markers on both leukemic and myelodysplastic syndrome stem cells. CD45RA was also shown to be an interesting marker for leukemic stem cells since they can be combined with CD34, CD38, and CD90 to approximate the cells found at the time of diagnosis. They also compared the most common genetic aberrations in MDS compared to AML. In AML, mutations in genes encode tyrosine kinase receptors in the RAS pathway. In MDS, there are more mutations involving epigenetic regulators and splicing proteins. The emergence of specific somatic mutations in high-risk MDS patients was found to be related to faster progression to AML. These mutations are non-linear since MDS stem cells gain those mutations in parallel. In their review of the metabolic activity of the malignant stem cells, they found that MDS stem cells demonstrate higher utilization of the citric acid cycle and oxidative phosphorylation. Hence, targeting these processes and hindering them acts as a possible method for treatment.Jawad et al. used data mining and databases to assess the effect of DNMT3A with arginine (R)882 mutations. They concluded that MDS with DNMT3A R882 mutations are associated with a higher number of blasts and increased risk of progression to AML when compared to non-R882 mutations. They demonstrated that a variety of clinical outcomes can result from DNMT3A mutations according to the type of mutation. R882 mutations lead to a markedly reduced methyltransferase activity which leads to an increased leukemogenic potential. However, DNMT3A was reduced in clonal hematopoiesis of indeterminate potential (CHIP) and MDS. The R882 mutation in MDS was a major prognostic indicator for severe leukopenia and reduced progression-free survival (PFS). It was also linked with a higher risk of progression to AML when compared to non-R882 mutations. This shows that selective inhibition of R882, allowing the wild-type DNMT3A to function, could be a possible treatment option. They also show that the risk of AML transformation in R882 mutations is dependent on SF3B1 and SRSF2 mutations since these mutations reduce the rate of transformation to zero in some studies.Moreover, Al-Bulushi et al. studied the impact of epigenetic mutations on prognosis and overall survival (OS) in AML. They concluded that ASXL1, TET2, DNMT3A, and IDH mutations have a negative effect on OS in AML patients. They found IDH to be linked with intermediate-risk patients , elderly patients, and patients with higher white blood cell (WBC) counts. Nevertheless, many studies included in the meta-analysis had several limitations and showed different results which show that more well-performed clinical research and data are necessary to confirm these findings.In addition, Ambinder and DeZern compared the characteristics of MDS and AML that may affect the prognosis and management of the diseases. MDS differs from AML as it shows a bone marrow blast percentage of less than 20% and no AML-defining genetic mutations. Nevertheless, this cutoff to diagnose AML may not always be effective in therapy, since some MDS patients may gain an increased benefit from AML-type treatment. Venetoclax-based therapy exhibited adequate safety and efficacy in high-risk MDS. They also discuss the importance of differentiating secondary AML from de novo AML since secondary AML is usually associated with poorer clinical outcomes. The presence of residual MDS cells with AML cells complicates treatment further since both should be treated simultaneously.Finally, Both authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.


These heterogeneous nanofibers were characterized by a wide variety of techniques to show mesoporous structure, high surface area, excellent stability, nanofiber morphology, highly efficient activity and selectivity towards the oxidation of starch and 5-hydroxymethylfurfural (5-HMF) either by H2O2 or by oxygen. POM/SiO2 nanofibers were suitable for oxidation of starch by H2O2 and oxidation of 5-HMF by O2 with high efficiency of 0.58 mol per 100 g carboxyl content and 89.2% yield of DFF; these results are comparable with those obtained using homogeneous H5PMo10V2O40 and HPMoV/SiO2 without nanofiber morphology. Furthermore, HPMoV/SiO2 nanofibers could be easily recycled and reused at least ten times with no significant loss of catalytic activity due to their nanofiber morphology.Polyoxometalate H 5PMo10V2O40/SiO2 nanofiber catalyst.The oxidation process for mesoporous H Controlled or selective oxidation of 5-HMF is desirable for targeting production of needed products, while the selectivity to catalysts and reaction conditions including solvent, time, and temperature is essential.With depletion of fossil resources and increasing concern about global warming, the sustainable production of fuels for transportation and useful chemicals from renewable carbon-containing biomass has attracted great attention.pathways . Selecti7,8 The highest efficiency with 100% selectivity and 99% conversion was obtained with Fe3Co7/C under reaction conditions of 100 °C for 6 h.9 The key point of conversion of 5-HMF to DFF is to selectively oxidize the –OH group without affecting other functional groups as well as the furan ring using various catalysts and oxidants including NaOCl, BaMnO4, pyridinium chlorochromate, and 2,2,6,6-tetramethyl-piperidine-1-oxide.10–12 Based on the “green concept”, the use of oxygen or air and heterogeneous catalysts is highly favorable and desirable.13 Noble metals loaded on supports have been used for aerobic oxidation of 5-HMF to DFF.14 Also, different transition metal catalysts have been developed in 5-HMF oxidation due to their low price; however, low yield of DFF was obtained without adding any initiator.15,16Among all oxidation products, DFF is an important monomer for industrial use and has been widely used for the synthesis of various poly-Schiff bases, pharmaceuticals, macrocyclic ligands, organic conductors and polymers.17 Due to global energy crisis and environment pollution, it is time to decrease the consumption of fossil fuels and seek regenerated feedstocks. Therefore, biomass is regarded as a promising raw material for the sustainable production of chemicals.18 POMs, especially HnPMon12−VnO40 , are widely applied as oxidative catalysts in biomass conversion using H2O2 or O2 as oxidants, including oxidation of lignin, cellulose, and 5-HMF.19,20 For example, Vigier and co-workers have achieved 84% yield of 2,5-diformylfuran (DFF) from fructose in one-step oxidation by HPMo11V1O40.21 In many cases, POMs used as homogeneous catalysts faced separation problems and exhibited hydrolytic instability under oxidative conditions.22 The need for environmentally benign and sustainable approaches for chemical transformations has increased the focus on recyclable heterogeneous catalysts instead of homogeneous ones. Under such circumstances, heterogeneous POM catalysts are developed using microporous, mesoporous and macroporous silica materials as supports, which are used in epoxidation and oxidation of organic substrates.23,24 Compared to powdered mesoporous silica materials, electrospun nanofibers are good candidates because of their high surface-to-volume ratios.25 Therefore, highly mesostructured nanofibers are of great importance and interest for special applications in some field such as optical materials and catalyst carriers.26,27 SiO2 nanofibers are available for loading POMs using a simple sol–gel method and atom transfer radical polymerization.28 However, a comparatively low surface area of common electrospun silica nanofibers without a mesoporous structure is a major drawback that hinders their wide application in catalysis, where a large reaction contact area has a significant influence on the reaction rates. Therefore, it is essential to fabricate electrospun POMs/SiO2 nanofibers with mesoporous structure and large surface area. In this case, we have made an effort to combine electrospinning and surfactant-directed pore formation techniques to synthesize H5PMo10V2O40/SiO2 nanofibers with a mesoporous structure and high surface area for the first time. The benefits of H5PMo10V2O40/SiO2 mesoporous nanofibers over POMs/SiO2 mesoporous nanopowders is the high contact area, exposing more active sites for catalysis, which might result in higher reaction rates. Polyoxometalates Cs3HPMo11VO40 and H3PMo12O40/MIL-101 were used in the aerobic oxidation of 5-HMF to DFF with 99% yield at 99% conversion and 88.2% yield at 90.8% conversion, respectively, in dimethyl sulfoxide (DMSO).29,30 Chen et al. also pointed that Mo- or V-containing Keggin POMs can promote the aerobic oxidation of 5-HMF to DFF, with CsH4PMo10V2O40 and Cs3H2PMo10V2O40 exhibiting selectivities of 99% and 92% for DFF, respectively. Despite the higher efficiency obtained by CsH4PMo10V2O40, the problem of separation of fine powers limits its further application. Therefore, Lee's group conducted the aerobic oxidation using H3PMo12O40 embedded on the pore of Cr-MIL-101, giving 88.2% yield of DFF at 90.8% conversion of 5-HMF under the reaction conditions of 140 °C and 20 h,29 showing that there is plenty room for fabrication POM solid hybrids using other strategies for the oxidation of 5-HMF.Polyoxometalates (POMs) are well-known redox catalysts in organic substrate transformation.2O2 or O2 has attracted much attention due to the various products available for wide application31 including oxidative starch,32 maleic anhydride from C5-biomass or C6-based polysaccharides,33–35 formic acid from cellulose carbohydrates,36–40 and 2,5-furan dicarboxylic acid (FDCA) or DFF from 5-HMF.41,42 The above oxidation could be achieved by using environmental benign oxidants of H2O2 or O2 combined with various homogeneous or heterogeneous catalysts, including metal oxides, Fe Fenton's reagents and polyoxometalates  (PVA) solution with a silica source, POMs and a surfactant were used as precursors to be electrospun and then calcined to remove the polymer and surfactant, which resulted in POMs/SiO2 nanofibers with a mesoporous structure. The hybrid catalysts can facilitate highly efficient oxidation of starch by H2O2 and aerobic oxidation of 5-HMF to DFF.Oxidation of biomass by H2.2.120PO20EO20  was purchased from Aldrich. 0.1 M of NaOH solution was used for determining the carboxyl content and acid strength by titration. H5PMo10V2O40 (HPMoV) was synthesized according to All chemicals were used as obtained from commercial suppliers and used without further purification. EO2.2−1) were recorded in KBr discs on a Nicolet Magna 560 IR spectrometer. The elemental analysis was carried out using a Leeman Plasma Spec (I) ICP-ES. The 31P-MAS NMR measurements were obtained using a Bruker AM500 spectrometer at 202.5 MHz. Energy dispersive X-ray (EDX) analysis was performed to calculate the Si, O, P, Mo and V elements. XRD patterns of the samples were collected on a Japan Rigaku Dmax 2000 X-ray diffractometer with Cu Kα radiation (λ = 0.154178 nm). UV-vis spectra (200–800 nm) were recorded on a Cary 500 UV-vis-NIR spectrophotometer. DR-UV-vis spectra (200–800 nm) were obtained on a UV-2600 UV-vis spectrophotometer (Shimadzu). SEM images were determined by a SU8010 scanning electron microscope. TEM micrographs were recorded on JEM-2100F instrument. Nitrogen adsorption was measured on an ASAP 2010M surface analyzer (the samples were outgassed under vacuum at 100 °C overnight). The total organic carbon (TOC) was measured by a TOC analyzer . The O2 adsorption was carried out by O2 temperature programmed desorption. The analysis of the recovered solutions was performed using high-performance liquid chromatography (HPLC). Samples were separated by a reverse-phase C18 column and detected by a UV detector at the wavelength of 280 nm. The mobile phase constituted of acetonitrile and 0.1 wt% acetic acid aqueous solution (v/v = 10 : 90) at 0.9 mL min−1.IR spectra (4000–400 cm2.3−4 mol) was dissolved in ethanol (6.3 mL) at room temperature as solution A. Tetraethyl orthosilicate  as a structure-directed agent was added to ethanol (21.3 mL) as solution B. The desired amount of H5PMo10V2O40 was dissolved in water (2.5 mL) in the range of 0.1–0.5 g (5.8 × 10−5 to 2.9 × 10−5 mol) to ensure 5–40% H5PMo10V2O40 loading. B solution was first added to A solution, then H5PMo10V2O40 aqueous solution was added to the above mixture at room temperature under stirring. The acidity of the mixture was controlled at pH = 1–2 using HCl (12 mol L−1), and then the mixture was stirred vigorously for 12 h at 40 °C to give HPMoV/silica precursor.The preparation of HPMoV/silica precursor was achieved as follows: P123 ). Other catalysts of microporous SiO2 powder (micro-SiO2), mesoporous SiO2 powder (meso-SiO2), microporous HPMoV/SiO2 powder with 18% H5PMo10V2O40 loading (HPMoV/micro-SiO2(18)) and mesoporous HPMoV/SiO2 with 18% H5PMo10V2O40 loading (HPMoV/meso-SiO2(18)) were synthesized according to literature.45–4710 mL of 10 wt% PVA aqueous solution was added dropwise into the above HPMoV/silica precursor, and then the mixture was heated at 60 °C for another 4 h to give the final viscous gel. The composite gel was placed in a plastic syringe. A copper pin connected to a high-voltage generator was inserted in the precursor syringe. A grounded iron drum covered with an aluminium foil served as the counter electrode. The HPMoV/SiO2.52O2 added depended on the length of the experiment, usually at a rate of 900 μL per 2 h for a total reaction time of 10 h. After the reaction, the mixture was filtrated immediately to separate the insoluble catalyst and washed with water several times for reuse. The filtrate was cooled down to room temperature to separate unreacted starch by centrifugation.In a typical reaction protocol, 1 g of starch and 4 mg of catalyst were mixed with 2.0 mL distilled water in the reactor with stirring for a period at the required temperature. The oxidation reaction was initiated by addition a certain amount of hydrogen peroxide. In order to confirm the best oxidized condtions for starch during the reaction, the total amount of hydrogen peroxide was added intermittently rather than adding the whole amount at one time. Furthermore, the amount of H2.6C = molar concentration of sodium peroxide, V − V0 = consumed volume of sodium hydroxide.300 mg of the resulting material (white powder) was dissolved in 20 mL of diluted water, and a few drops of phenolphthalein solution in EtOH were added as the indicator. The solution was titrated with 0.1 M of NaOH solution until the colour of the solution changed to pink. The degree of oxidation with respect to the percentage of carboxyl groups (mol per 100 g) presented in the polymer is calculated according to the following equation:2.749Aerobic oxidation of 5-HMF was carried out in a Teflon-lined autoclave equipped with a magnetic stirrer. In a typical experiment, 1 mmol of 5-HMF and 80 mg of catalyst were added into 5 mL of DMSO; then the mixture was heated to 120 °C. During the reaction, the reactor was maintained at 1.0 MPa oxygen pressure. After the reaction, the reactor was cooled to room temperature. The solid catalyst was separated from the mixture by centrifugation and then washed with ethanol several times and dried in an oven at 40 °C for 12 h for reuse.3.3.13PW12O40/silica hybrids using a triblock copolymer surfactant (P123) as the pore director through sol–gel co-condensation combined with a hydrothermal method.47 Therefore, the preparation of H5PMo10V2O40/SiO2 nanofibers with a mesoporous structure used the same surfactant-directed pore formation method without hydrothermal treatment, and then via electrospinning to generate nanofibers  scale" fill="currentColor" stroke="none"><path d="M80 600 l0 -40 600 0 600 0 0 40 0 40 -600 0 -600 0 0 -40z M80 440 l0 -40 600 0 600 0 0 40 0 40 -600 0 -600 0 0 -40z M80 280 l0 -40 600 0 600 0 0 40 0 40 -600 0 -600 0 0 -40z"/></g></svg>(Si–OH2)+ H4PMo10V2O40 and further Po70EOm−y[(EO)·H3O+]y⋯yCl−⋯H5PMo10V2O40/Si(OEt)n4−(OH2+)n in the presence of strong Brønsted acid HCl.46 During sol formation, there had strong interaction between the POM units and the silica matrix. Second, silica sol was heated at 40 °C for 12 h, forming gel particulates. Then PVA and silica gel were spun together giving polymer/silica nanofibers. After removal of the surfactant and polymer by calcination, mesoporous H5PMo10V2O40/SiO2 nanofibers were formed.Previously, Guo's group had designed mesostructured Hnofibers . First, 3.22(f) with different loading amounts of H5PMo10V2O40 are given in 5PMo10V2O40 retained the Keggin structure during the preparation. The loading amounts of H5PMo10V2O40 in the hybrids were 7–35%. The structural integrity of the Keggin unit was further confirmed by IR spectra  and HPMoV/meso-SiO2(f)  gave almost the same characteristic peaks in the range of 1100–700 cm−1, which were assigned to the Keggin unit of υas(P–Oa), υas(Mo–Od), υas(Mo–Ob–Mo), and υas(Mo–Oc–Mo), respectively. It could be seen that no significant interference on the IR spectrum signals originated from Keggin units, while υas(P–Oa), υas(Mo–Od), υas(Mo–Ob–Mo), and υas(Mo–Oc–Mo) were observed with some blue shifts after the formation of HPMoV/SiO2 materials. Such shifts of the IR peaks were due to the strong interactions between POM anion and silica support. Meanwhile, the stretching vibration of Si–O–Si for the SiO2 support was observed at 1084 cm−1,50 and a broad peak at 1073 cm−1 was found in HPMoV/meso-SiO2(f) due to the strong interaction of the Keggin anion and SiO2 support.The elemental analyses of HPMoV/meso-SiO spectra . The IR 2(f) were showed in θ of 15–35° was observed for the nanofibers with H5PMo10V2O40 loading lower than 18 wt%, which was assigned to amorphous silica. There were no diffraction peaks corresponding to the starting H5PMo10V2O40 in HPMoV/meso-SiO2(n-f) nanofibers with H5PMo10V2O40 loading lower than 18 wt%. When the loading amount was increased to 28.8 wt% or more, diffraction peaks for H5PMo10V2O40 were found at 8.86° (101), 9.24° (002), 18.62° (212), 28.01° (323). The above results indicated that H5PMo10V2O40 molecules were homogeneously dispersed in the composites with lower loading amounts (<18 wt%), while they were unevenly dispersed or aggregated across the nanofibers at higher loading amounts. The DR-UV-vis spectra of the HPMoV/meso-SiO2(n-f) are given in Fig. S1.2(n-f), which was attributed to the electron transmission of molybdenum to oxygen. This proved that H5PMo10V2O40 was successfully modified on the mesoporous SiO2 nanofibers.The wide-angle XRD patterns of HPMoV/meso-SiO31P-MAS NMR was used to confirm the structural integrity of the Keggin anion in silica nanofibers and the presence of the interaction between silica and POMs (31P-NMR of HPMoV/meso-SiO2(18-f) gave two peaks at −4.88 and −5.96 ppm (10V2O405− (−4.55 ppm),51 indicating the structural integrity of the Keggin unit in silica nanofibers. A small peak at −5.96 ppm confirmed the strong interaction of Si–O–W occurrence, which permitted less leaching of POMs from the support. The SEM images of HPMoV/SiO2/polymer and HPMoV/meso-SiO2(n-f) are given in 2/polymer consisted of uniform fibers with a diameter of 400–500 nm and good dispersity. After calcination at 350 °C for HPMoV/SiO2/polymer to remove the polymer and surfactant, the as-prepared HPMoV/SiO2 hybrids shrank to 200–400 nm in diameter due to the decomposition of PVA and gelation of TEOS. In addition, the TEM images (2(18-f) revealed that HPMoV/meso-SiO2(18-f) was three-dimensionally interconnected pore-network structure with poor ordering but high porosity.47 Meanwhile, H5PMo10V2O40 was observed as dark spots on SiO2 with uniform dispersion.The and POMs . The 31P5.96 ppm . A peak M images  of HPMoV2 porosimetry results of HPMoV/meso-SiO2(n-f) are shown in 1 hysteresis loops at a relative pressure (P/P0) of 0.45–0.90, indicating the hybrid catalysts had regular mesopores.52 This result was consistent with the XRD and TEM results and further proved the mesostructure of HPMoV/meso-SiO2(n-f). From 2(n-f) materials had uniform pore sizes and the Keggin units were homogeneously distributed across the sol–gel co-condensed materials.The pore sizes and N3.32(n-f) were used in oxidation of starch by H2O2 under the reaction conditions: 1 g of starch, 2 mL of distilled water, 4.5 mL of hydrogen peroxide (30%), and 4 mg of catalyst at 70 °C for 10 h. In order to evaluate the influence of structure, pore size and morphology on catalytic activity, various catalysts were selected to be compared including micro-SiO2, meso-SiO2, micro-SiO2(f), meso-SiO2(f), HPMoV/micro-SiO2(18), HPMoV/micro-SiO2(18-f), HPMoV/meso-SiO2(18), HPMoV/meso-SiO2(18-f) and H5PMo10V2O40. It can be seen that without any catalysts  was determined by IR spectrum of HPMoV/meso-SiO2(18-f) after absorbing starch  without nanofiber morphology could also adsorb some starch, but the amount of adsorbed starch was different, as 0.3 g g−1 for HPMoV/meso-SiO2(18) compared to 0.5 g g−1 for HPMoV/meso-SiO2(18-f), due to the nanofiber structure exhibiting sufficient length, high porosity and ultrahigh surface-to-volume ratio could adsorb more starch.53 HPMoV/meso-SiO2(18) without nanofiber morphology presented a BET surface area of 431.6 m2 g−1 (2(18-f). Therefore, the difference in catalytic activity between the nanofibers and nanoparticles of HPMoV/SiO2 was expected to have different morphologies. At last, HPMoV/meso-SiO2(18-f) presented the highest oxidation activity with a carboxyl content as 0.58 mol per 100 g among all catalysts, including the homogeneous one H5PMo10V2O40, silica materials, and other HPMoV/silica catalysts without a nanofiber morphology. Meanwhile, the solid products were obtained with different yields; homogenous H5PMo10V2O40 only gave 72.0% yield of solid oxidative starch and HPMoV/meso-SiO2(18-f) presented 88.0% yield. This indicated that after being loaded on meso-SiO2, some active sites become embedded, which could hinder further oxidation occurrence.First, HPMoV/meso-SiOatalysts , starch  Fig. S2c. It coul6 m2 g−1 , which w5PMo10V2O40 and HPMoV/meso-SiO2(n-f) was attributed to the different decomposition rates for H2O2 . This result indicated that active sites of H5PMo10V2O40 were surrounded by the Si–O matrix, resulting in lower decomposition rate for H2O2, while the decomposition of H2O2 depended on its loading amount on silica. In our previous report,47,48 the oxidation of starch underwent singlet oxygen and OH˙ radical mechanism, while the decomposition of H2O2 to O2 could hinder the oxidation of starch. Therefore, two competing reactions based on H2O2 including oxidation of starch and decomposition into O2 were balanced by HPMoV/meso-SiO2(18-f). The H5PMo10V2O40 molecule was embedded in to silica, which could prevent the decomposition of H2O2 and HPMoV/meso-SiO2(18-f) gave the highest carboxyl content of 0.58 mol per 100 g. HPMoV/meso-SiO2(18) without nanofibers showed higher activity in H2O2 decomposition than nanofibers, which was due to its higher BET surface area than nanofibers. The utilization of H2O2 using H5PMo10V2O40, HPMoV/meso-SiO2(7-f), HPMoV/meso-SiO2(14-f), HPMoV/meso-SiO2(18-f), HPMoV/meso-SiO2(28.8-f), and HPMoV/meso-SiO2(35-f) could confirm this point  > HPMoV/meso-SiO2(18) > HPMoV/meso-SiO2(14-f) > HPMoV/meso-SiO2(7-f) > HPMoV/meso-SiO2(28.8-f) > HPMoV/meso-SiO2(35-f) > H5PMo10V2O40, while the utilization of H2O2 was measured by the titration of Ce(SO4)2 in oxidation of starch.54The difference between homogeneous H Fig. S3a; H2O2 wa Fig. S3b. The uti5PMo10V2O40 influenced the oxidative degree of starch in 5PMo10V2O40 from 0 to 18 wt%, the carboxyl content was increased from 0.25 to 0.58 mol per 100 g, respectively. However, the carboxyl content was not enhanced on further increasing the H5PMo10V2O40 loading. The decreasing trend was attributed to the decrease in BET surface area and pore sizes with increase in H5PMo10V2O40 loading and the decomposition of H2O2 had a negative effect on starch oxidation.The loading amount of H2(18-f) were used as catalysts in the oxidation of starch and other reaction conditions were optimized (2(18-f), temperature and H2O2 dosage were also studied in 2O2 and starch gelatinization at high temperature.552O2. The usage of H2O2 was also optimized   on activity is given in 2(18-f). This result further demonstrated that there were two competing reactions in oxidation by H2O2: one is the oxidation of starch and the other is the decomposition to H2O2 to O2 and H2O. It could be concluded that increasing the usage of catalyst resulted in faster H2O2 decomposition and 4.0 mg of HPMoV/meso-SiO2(18-f) was the best choice. Finally, the optimized conditions for oxidation of starch through HPMoV/meso-SiO2(18-f) and H2O2 were 1 g of starch, 2 mL of distilled water, 4.5 mL of hydrogen peroxide (30%), and 4 mg of catalyst at 70 °C for 10 h, obtaining a carboxyl content as high as 0.58 mol per 100 g. In comparison with the reported POMs and FeSO4  Fig. S6. Therefo Table S2, it coul3.42(n-f) were successfully used as catalysts in H2O2 oxidation of starch. Oxygen is regarded as a more environmental benign oxidant than H2O2 in organic transformation. Therefore, catalyzing O2 to oxidize bio-platform chemicals is of great value. The different activity on 5-HMF oxidation by O2 was achieved using various solid catalysts including micro-SiO2, meso-SiO2, micro-SiO2(f), meso-SiO2(f), HPMoV/micro-SiO2(18), HPMoV/micro-SiO2(18-f), HPMoV/meso-SiO2(18), HPMoV/meso-SiO2(18-f) and H5PMo10V2O40 under the reaction conditions of 1 mmol of 5-HMF and 80 mg of catalyst at 120 °C for 8 h  and HPMoV/meso-SiO2(18) nanopowders were more active than pure silica supports, while the DFF yields were 33.9% and 2.9% at 51.3% and 72.9% conversions, respectively, under the same reaction conditions 1 mmol of 5-HMF and 80 mg of catalyst at 120 °C for 8 h). Using HPMoV/meso-SiO2(18-f), significant improvement in DFF yield to 89.2% at 92.7% conversion was achieved. Due to H5PMo10V2O40 embedded on the silica matrix, the over-oxidation of DFF to FDCA even CO2 was effectively prevented /[ × ] at 120 °C and H3PMo12O40 (PMA)-MIL-101 (TOF = 163.2 mol mol−1 h−1) at 140 °C, and an enhanced TOF value of 242.1 mol mol−1 h−1 at 120 °C was obtained for HPMoV/meso-SiO2 nanofibers.HPMoV/meso-SiO for 8 h . It coulo10V2O40 , it was t Fig. S7, which prevented . Increas2(18) nanopowders, HPMoV/meso-SiO2(18) nanofibers presented improved activity with almost 37.9% and 16.2% increase in DFF yield, respectively. This improvement was attributed to the effect of nanofiber morphology of solid catalysts on the uptake amount of oxygen. The oxygen uptake of different catalysts is shown in Table S3.5PMo10V2O40 (5.06 × 10−7 mol g−1) loading on the SiO2 support. HPMoV/meso-SiO2(18) nanofiber and HPMoV/meso-SiO2(18) nanopowder content was 5.6 × 10−5 mol g−1 and 4.3 × 10−5 mol g−1, respectively, which showed almost 1.3 times enhancement. Meso-SiO2 nanofibers with a hierarchical mesoporous internal structure possessed gas-adsorption characteristics.56 As shown in Fig. S8,57 From Fig. S8,2 nanofibers were prone to uptake oxygen, which provided more accessibility for 5-HMF being oxidized by O2.In comparison with microporous and mesoporous HPMoV/SiO5PMo10V2O40 on SiO2 mesoporous nanofibers (2(7-f) was used as the catalyst. A maximum yield of 89.2% at 92.7% conversion was obtained using HPMoV/meso-SiO2(18-f). Then on further increasing the loading of H5PMo10V2O40, the yield of DFF decreased to 77.6% only with slight increase in 5-HMF conversion. This result showed that higher H5PMo10V2O40 loading could promote the conversion of 5-HMF, but also led to a decrease in the BET surface area and pore size, which were unfavorable for the interaction between the reactant and active sites. Meanwhile, higher loading of H5PMo10V2O40 led to lower selectivity to DFF, which was due to the over-oxidation of DFF to FDCA.The oxidation of 5-HMF depended on the loading amount of Hnofibers . 77.3% 52 pressure, usage of catalyst, and reaction temperature on catalytic activity by O2 and HPMoV/meso-SiO2(18-f) were also studied. As shown in N,N-dimethylformamide (DMF). In the water system, the catalytic activity was negligible with 11.0% yield of DFF at 50.1% conversion of 5-HMF, presumably due to the hydration of the aldehyde group in 5-HMF to geminal diols in water.58 In organic solvents, the conversion of HMF followed the order of DMF (91.0%) < ethanol (92.3%) ∼ DMSO (92.7%) < toluene (96.1%) < MIBK (99.7%) under HPMoV/meso-SiO2(18-f) catalyst, while the DFF yields followed the range of DMF (31.6%) < MIBK (49.0%) ethanol (68.6%) < toluene (77.5%) < DMSO (89.2%). Generally speaking, the selectivity of DFF depended on the polarity of solvents using HPMoV/meso-SiO2 catalyst and strong polarity and high boiling points were beneficial for 5-HMF conversion. The effects of organic solvents on the oxidation of 5-HMF were complicated, which might be due to the properties of solvents including polarity, dielectric constant, steric hindrance, and acid–base properties. Our results only provided the brief solvent effect on HMF oxidation; more in-depth investigation needs to be performed in the future. Nevertheless, the strong polarity and high boiling point solvent DMSO was found to be the best solvent for the transformation, in comparison to DMF, MIBK, toluene, and ethanol. Therefore, DMSO as the solvent was a suitable medium for oxidation of 5-HMF.The effects of other parameters including solvent and OThe influence of oxygen pressure was on DMSO with 80 mg of catalyst was investigated. The obtained results showed that higher oxygen pressure could enhance 5-HMF conversion, which enhanced oxygen pressure from 0.5 to 1.0 MPa, giving increased 5-HMF conversions from 86.3 to 92.7% and increased DFF yields from 80.5 to 89.2%, respectively. However, further increasing oxygen pressure to 1.5 MPa only enhanced HMF conversion to 97.0% but decreased yield of DFF, which was attributed to over-oxidation. Herein, the most suitable oxygen pressure was 1.0 MPa for oxidation of 5-HMF to DFF.2(18-f). Increasing the temperature promoted the aerobic oxidation of 5-HMF to DFF, while DFF yields sharply increased from 11.6% at 80 °C to 89.2% at 120 °C under the investigated conditions. A further enhancement of the reaction temperature to 130 °C resulted in a steep decrease in the DFF yield to 61.2%.The influence of catalyst usages was investigated, which indicated that a lower conversion of 5-HMF with undesirable yield of DFF was obtain at 8 h reaction using lower usage of catalyst . Further3.52(18-f) was separated from the reaction mixture by simple centrifugation and was reused by simply washing with H2O and drying at 80 °C. It could be seen that the carboxyl content for starch oxidation and DFF yields for 5-HMF oxidation showed only a slight decrease after ten cycles  could be explained by the operation loss during recycling. The total loss of H5PMo10V2O40 were only 3.0% and 2.8%, respectively, corresponding to two reactions being tested by ICP, in which the loading amount of H5PMo10V2O40 on silica did not change during the reaction. The leaching test for HPMoV/meso-SiO2(18-f) was also performed to determine the leaching of H5PMo10V2O40 from silica. For starch oxidation, the catalyst was separated from the mixture by filtration after reaction for 2 h (0.35 mol per 100 g carboxyl content), and then the residual mixture further reacted for 2 h under the same conditions. For 5-HMF oxidation, the catalyst was separated by filtration after 1 h , and then the filtrate was continually reacted for 1 h at the same conditions. After that, 0.1 mol per 100 g carboxyl content and 1.4% of 5-HMF conversion were achieved, which proved that negligible H5PMo10V2O40 dropped from the solid silica into the mixture during two reactions.After each run, HPMoV/meso-SiOn cycles . To inves Fig. S8 no matte2(18-f) did not significantly differ from that of the fresh one, indicating that the structure of the heteropolyanion remained intact  showed that the mesoporous structure did not change during the oxidation reaction (Fig. S11The TEM of HPMoV/meso-SiO Fig. S11. Meanwhi Fig. S11 showed l4.2 nanofibers with a mesoporous structure were successful synthesized via combined surfactant-directed pore formation and electrospinning techniques. This method provided a facile approach to fabricate mesoporous structural POM catalysts with unique physical properties such as high surface area, one-dimensional nanofiber morphology and excellent stability, which permitted HPMoV/SiO2 nanofibers to present higher efficiency in oxidation of starch by H2O2 and aerobic oxidation of HMF as well giving as high as 0.58 mol per 100 g carboxyl contents and 89.2% yield of DFF. One-dimensional nanofiber morphology and surrounded by silica support assisted POMs exhibited higher activity than homogeneous H5PMo10V2O40 and HPMoV/SiO2 without nanofiber morphology, which was due to the adsorption of more O2 and the limited decomposition of H2O2. HPMoV/SiO2 mesoporous nanofibers could be separated easily through filtration and could be reused for at least ten times without obvious decrease in catalytic activity in comparison with that of HPMoV/SiO2 mesoporous powder. Moreover, the oxidative starch and DFF were produced with highest TOF among the reported POM-based catalysts, indicating the availability for HPMoV/SiO2 mesoporous nanofibers in biomass conversion.New POM solid catalyst HPMoV/SiOThere are no conflicts to declare.RA-008-C7RA12842H-s001


This suggests a role for Cdk5 in regulating intracellular Ca2+ dynamics, but how Cdk5 is involved in this process remains to be explored. Using ex vivo primary mouse embryonic fibroblasts (MEFs) isolated from Cdk5−/− mouse embryos, we show here that loss of Cdk5 causes an increase in cytosolic Ca2+concentration ([Ca2+]cyt), which is not due to reduced internal Ca2+ store capacity or increased Ca2+ influx from the extracellular milieu. Instead, by stimulation with ATP that mediates release of Ca2+ from internal stores, we determined that the rise in [Ca2+]cyt in Cdk5−/− MEFs is due to increased inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca2+ release from internal stores. Cdk5 interacts with the IP3R1 Ca2+ channel and phosphorylates it at Ser421. Such phosphorylation controls IP3R1-mediated Ca2+ release as loss of Cdk5, and thus, loss of IP3R1 Ser421 phosphorylation triggers an increase in IP3R1-mediated Ca2+ release in Cdk5−/− MEFs, resulting in elevated [Ca2+]cyt. Elevated [Ca2+]cyt in these cells further induces the production of reactive oxygen species (ROS), which upregulates the levels of Nrf2 and its targets, Prx1 and Prx2. Cdk5−/− MEFs, which have elevated [Ca2+]cyt, proliferate at a faster rate compared to wt, and Cdk5−/− embryos have increased body weight and size compared to their wt littermates. Taken together, we show that altered IP3R1-mediated Ca2+ dynamics due to Cdk5 loss correspond to accelerated cell proliferation that correlates with increased body weight and size in Cdk5−/− embryos.Loss of cyclin-dependent kinase 5 (Cdk5) in the mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) increases ER–mitochondria tethering and ER CaThe online version contains supplementary material available at 10.1007/s00018-022-04515-8. The role of Cdk5 in regulating intracellular Ca2+ dynamics has been primarily examined in neurons where it is abundantly expressed mt. This points to a role for Cdk5 in regulating intracellular Ca2+ dynamics. Indeed, Cdk5 localizes in the MAM ER-mitochondria interface cyt and ROS signaling has been reported cyt. These Cdk5-mediated Ca2+ dynamics are reflected in the disrupted Ca2+-mediated proliferation of Cdk5−/− MEFs and development of Cdk5−/− embryos.In this study, we utilized the 2-DCFDA, MitoSOX red, MitoTracker green, Fluo-4 AM, Mag-Fluo-4 AM, ionomycin, GlutaMAX and an antibody against p27KIP1  were from ThermoFisher Scientific . Mito-tempo and antibodies against Cdk5 (C-8), tubulin (D-10), IP3R1 (E-8), p21CIP1 (L-17), Prx1 (N-19) and actin (I-19) were from Santa Cruz Biotech . The polyclonal antibodies against the two IP3R1 phosphopeptides, MLKIGTpS421VKEDKE and HVDRDPQEQVpT799PVK, were generated by GL Biochem. Ltd . The phosphoThr202/Tyr204-ERK1/2 antibody was from Cell Signaling . The Ki67 (ab92353), Prx2 (ab109367), GAPDH (6C5) and Nrf2 (ab31163) antibodies and BAPTA-AM (ab120503) were from Abcam . The protease inhibitor cocktail, ATP and XeC were from Sigma . Thapsigargin (TG) was a gift from Dr. Andrew Braun at the University of Calgary. The IP3R1 siRNAs were synthesized at the University of Calgary Core DNA Services. The peroxidase and serum-free protein block kits were from Dako . The avidin and biotin block kit and DAB were from Zymed . The secondary antibodies were from Jackson ImmunoResearch Labs . The Vectastain® ABC Reagent was from Vector Laboratories . ECL reagent was from GE Healthcare . Jet prime transfection reagent was from Polyplus transfection .Dulbecco’s modified eagle’s medium (DMEM), heat-inactivated fetal bovine serum (FBS), EDTA-Trypsin, antibiotic–antimycotic, HCdk5−/− embryos that we used in our studies were generated by intercrossing Cdk5+/− mice  maintained at the University of Calgary Animal Facility. Wt littermates were used as controls. All animal studies conformed to regulatory standards and were approved by the University of Calgary Health Sciences Animal Care Committee.The /++ and Cdk5−/−embryos as described previously [2 and 5% CO2) at 37 °C. All experiments were performed using passage 2 to 7 (P2-P7) MEFs.Primary MEFs were isolated from E13.5 Cdk5eviously . Briefly2+]cyt, trypsinized 0.5 × 106 MEFs were loaded with 5 µM Fluo-4 AM in DMEM for 1 h at room temperature. Cells were then washed three times with Ca2+-free EGTA-containing KRH buffer  and analyzed using a Shimadzu RF 5301PC spectrofluorometer. To minimize background fluorescence, 40 µM EDTA was added before reading the F values. Fmax value was obtained after treatment with 0.02% saponin and addition of 2 µM CaCl2 three times . Fmin value was taken upon addition of 4 mM EDTA. [Ca2+]cyt was calculated using the formula: free [Ca2+]cyt = Kd [F–Fmin]/[Fmax–F] [Kd (for Fluo-4) = 345 nM. (ii) To measure [Ca2+]cyt transients by single-cell Ca2+ imaging, MEFs were seeded in 3.5 cm glass bottom petri dishes and stained with 5 µM Fluo-4 AM in HBSS (with 1.26 mM Ca2+) for 30 min at room temperature (RT). Cells were then washed three times with KRH buffer and analyzed by single-cell Ca2+ imaging using a Zeiss LSM 510 Meta confocal laser scanning microscope (20 × objective). Fluorescence signals were measured in 10–20 cells. Peak amplitudes were quantified as ratios of fluorescence (F/F0) after addition of ATP, XeC or TG. F0 represents basal fluorescence or fluorescence before stimulation. (iii) To measure ER Ca2+, MEFs were seeded in 3.5 cm glass bottom petri dishes and stained with 5 µM Mag-Fluo-4 AM in DMEM for 30 min at RT. Cells were then permeabilized with 0.1 mg/ml saponin for 45 s, washed with ICM buffer  three times and analyzed using a Zeiss LSM 510 Meta confocal microscope (20 × objective). Fluorescence signals were measured in ten cells and quantified as ratios of fluorescence (F/F0) after addition of 500 nM IP3. F0 represents basal fluorescence or fluorescence before stimulation.(i) To measure resting [Ca[Fmax–F] , whereas5) seeded in 6 cm dishes were transfected with 100 nM IP3R1 siRNA #1 (AACATTGTGCAGAAAACAGCC) or #2 (AACAAAGAGATCCGTAGTAAG) for 48 h using Jet prime transfection reagent following the manufacturer’s protocol.MEFs (2.5 × 10421A IP3R1 and S421D IP3R1 were custom-generated by Genscript (USA). The IP3R also carries silent mutations: 2118 G > A, 2121 C > A, 2122 C > A, 2124 T > G, 2125 A > T and 2126 G > C that do not alter the IP3R1 amino acid sequence but confer resistance to IP3R1 siRNA #2. MEFs (5 × 105) seeded in 6 cm dishes were co-transfected with IP3R1 siRNA (100 nM) and pcDNA 3.0 carrying S421A IP3R1 or S421D IP3R1 (2 µg) as per the Lonza nucleofector protocol (Basel Switzerland).pcDNA 3.0 carrying rat IP3R1 was obtained from Dr. I. Bezprozvanny at the University of Texas Southwestern Medical Center at Dallas. S5) seeded in 3.5 cm dishes were treated with 3 µM XeC, 10 µM ionomycin or 50 µM BAPTA-AM for 30 min. Cells were then washed with KRH buffer and harvested using trypsin. Cytoplasmic hydrogen peroxide and mitochondrial superoxide levels were measured by staining with 5 µM H2-DCFDA and 5 µM MitoSOX red, respectively, in KRH buffer for 30 min at 37 °C. Cells were then washed and resuspended in KRH buffer and analyzed by flow cytometry using a fluorescein isothiocyanate filter (530 nm) for DCFDA, a phycoerythrin filter (575 nm) for MitoSOX red.(i) For live-cell imaging, MEFs seeded in 4-chamber cover glass (Lab-Tek) were stained with 5 µM DCFDA or 200 nM MitoTracker green + 5 µM MitoSOX red to measure cytoplasmic hydrogen peroxide or mitochondrial superoxide levels, respectively. Images were taken using an Olympus 1X71 fluorescence microscope at 160 × magnification. (ii) By flow cytometry, MEFs (2.5 × 103 MEFs were seeded in 96 well plates (n = 3). Cdk5−/− MEFs were treated (or untreated) with 3 µM XeC. After 1, 3 or 6 days in culture, cells were harvested using trypsin and stained with trypan blue, and viable cells were counted using a hemocytometer under an Olympus CK40 microscope.1 × 10Immunoprecipitation (IP) of clarified MEF lysates in lysis buffer  was performed using IP3R1 (E-8) antibody. IP samples or cell lysates were resolved by SDS–polyacrylamide gel electrophoresis (PAGE) and proteins were transferred onto nitrocellulose membranes, which were blocked in 5% skimmed milk and then incubated with the indicated primary antibody at 4 °C overnight. After washing with TBST buffer, containing 50 mM Tris–HCl, pH 7.6, 0.8% NaCl and 0.1% Tween-20, membranes were incubated with horseradish peroxidase-conjugated secondary antibody for 1 h. Immunoreactive bands were detected using ECL reagent (Amersham).® ABC reagent for 30 min followed by DAB for 5 min. Tissue staining was visualized and photographed using an Olympus I ×71 light microscope with an attached Photometrics Coolsnap FX camera from Roper Scientific .E13.5 mouse embryos fixed in 4% paraformaldehyde (PFA) were sectioned to 10 µM thickness using a Leica RM2235 microtome. Tissue sections mounted on glass slides were incubated initially with peroxidase and then with avidin and biotin using a block kit followed by a serum-free protein block kit to eliminate non-specific binding of the primary antibody. The slides were then incubated with a Ki67 antibody at 1:100 dilution for 2 h, washed, and incubated with a secondary antibody for 40 min. Ki67-positive cells were detected by incubating with Vectastain2+]cyt effect on ROS level, (ii) proliferation, and (iii) IP3-induced Ca2+ release were analyzed by one-way ANOVA. All other data were analyzed by Student’s t test. Significance was set at p < 0.05.Cdk5-regulated (i) [Ca2+ concentration ([Ca2+]mt) by controlling ER Ca2+ transfer to the mitochondria [2+ concentration ([Ca2+]cyt). To do so, we initially performed spectrofluorometric analysis to measure resting [Ca2+]cyt in Fluo-4 AM-loaded primary MEFs cyt. We then examined three possible mechanisms that may have caused the rise in [Ca2+]cyt in Cdk5−/− MEFs: (i) reduced internal Ca2+ store capacity, (ii) increased Ca2+ influx from the extracellular milieu, and (iii) increased Ca2+ release from internal Ca2+ stores. We began by treating wt and Cdk5−/− MEFs with thapsigargin (TG), a potent non-competitive inhibitor of the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) pump cyt in Cdk5−/− MEFs is due to internal store Ca2+ release by loading cells with Fluo-4 AM and treating them with ATP in Ca2+-free EDTA-containing buffer. By single-cell Ca2+ imaging analyses using a confocal laser scanning microscope, we found that 0.1 µM  pump , that emr p < 0.0 comparedeceptors , inducesl stores  in Ca2+-r p < 0.0 comparedr p < 0.0 compared2+]cyt in Cdk5−/− MEFs occurs through IP3R. As shown in Fig. 2+]cyt increase in both wt and Cdk5−/− MEFs, indicating that such [Ca2+]cyt increase is mediated by IP3R, which forms Ca2+ channels in the internal Ca2+ stores cyt on ROS level. To do so, wt and Cdk5−/− MEFs treated with XeC, ionomycin or BAPTA-AM and then stained with DCFDA  mt by controlling ER Ca2+ transfer to the mitochondria cyt can activate Ca2+-induced Ca2+ release (CICR) cyt.Since IP3R-mediated Carylation , and Cdkrylation , has two3R1 S421 . Althougto IP3R1 , its eff as well , 40. Sine (CICR)  from the2+]cyt, loss of Cdk5 in MEFs further induces ROS production. The ability of XeC and BAPTA-AM to reverse the increase in ROS level in Cdk5−/− MEFs indicates that ROS production occurs downstream of the IP3R1-mediated increase in [Ca2+]cyt in these cells. Interestingly, we found that increased ROS production in Cdk5−/− MEFs is associated with increased proliferation. Since increased ROS also induces apoptosis, it is possible that ROS-associated upregulation of Nrf2 and its antioxidant protein targets, Prx1 and Prx2, in Cdk5−/− MEFs acts in a feedback control loop, ensuring that the ROS level in these cells does not exceed the threshold level that triggers apoptosis. This notion indicates the adaptability of MEFs under increased oxidative stress condition.In addition to triggering a rise in free cyt through IP3R1, proliferate at a faster rate compared to wt. The ability of XeC to reverse the increase in Cdk5−/− MEF proliferation to a level equivalent to that in wt supports our view that accelerated proliferation in Cdk5−/− MEFs is linked to IP3R-mediated increase in [Ca2+]cyt. This is consistent with previous reports that Cdk5 plays an inhibitory role in the neuronal cell cycle [KIP1 in Cdk5−/− MEFs is consistent with the fact that IP3R-mediated Ca2+ oscillations stimulate proliferation through downregulation of p27KIP1 [Cdk5−/− MEFs correlates with increased weight and size in E16.5 Cdk5−/− embryos, and increased number of Ki67-positive cells in various embryonic tissues, including prefrontal cortex, olfactory epithelium, lung and duodenum. Although we observed the same trend in body weight and size in earlier E13.5 Cdk5−/− embryos, we note that later E18.5 Cdk5−/− embryos were lighter and smaller than their wt counterparts. This may be due to the development of other abnormalities in Cdk5−/− embryos as they exhibit perinatal mortality. It is known that ~ 64% of Cdk5−/− embryos die in utero and newborns are either dead or weak and die within 12 h after birth [Cdk5−/− embryos are consistent with reduced levels of the cell-cycle inhibitors, p21CIP1 and p27KIP1, and increased body weight in p27KIP1 knockout mice [Cdk5 and IP3R-mediated Cagression , 11, 53 gression –19. Thusll cycle , 10, 11.er birth . Nonetheout mice .2+ dynamics through phosphorylation of IP3R1 at Ser421, and Ca2+-mediated cell proliferation as indicated by increased Cdk5−/− MEF proliferation that correlates with increased body weight and size in Cdk5−/− embryos.In summary, we provide evidence that Cdk5 controls intracellular CaSupplementary file1 (PDF 155 KB)Supplementary file2 (JPG 308 KB)Supplementary file3 (JPG 1249 KB)Supplementary file4 (JPG 1260 KB)Supplementary file5 (JPG 1319 KB)Supplementary file6 (JPG 991 KB)Supplementary file7 (JPG 480 KB)Supplementary file8 (JPG 315 KB)Supplementary file9 (JPG 404 KB)Below is the link to the electronic supplementary material.


We experimentally demonstrate the prototype building blocks of this system, and evaluate the scaling behavior of the system using simulations. Our work not only provides a pathway to realizing CMOS-compatible designs but also to overcoming their scaling challenges.Realizing compact and scalable Ising machines that are compatible with CMOS-process technology is crucial to the effectiveness and practicality of using such hardware platforms for accelerating computationally intractable problems. Besides the need for realizing compact Ising spins, the implementation of the coupling network, which describes the spin interaction, is also a potential bottleneck in the scalability of such platforms. Therefore, in this work, we propose an Ising machine platform that exploits the novel behavior of compact bi-stable CMOS-latches (cross-coupled inverters) as classical Ising spins interacting through highly scalable and CMOS-process compatible ferroelectric-HfO However, the highly interconnected nature of the system also poses a significant implementation and scalability challenge for Ising platforms. In fact, the number of coupling elements (representing edges) required for mapping an arbitrary graph scales up quadratically (~ N2) with the number of nodes in the graph. Consequently, scaling the system to large sizes continues to be a significant challenge for most Ising machine designs. Our approach to addressing this challenge relies on developing novel hardware components that are not only compact but can also leverage the maturity of CMOS-process technology and integration.Ising Machines, as dynamical systems, have recently shown promise for accelerating computationally challenging problems in combinatorial optimization. The intrinsic energy minimization in the highly interconnected system gives rise to rich spatio-temporal properties, which can subsequently be mapped to the solutions of many computationally intractable optimization problems16, each with their advantages and shortcomings, that have been considered for implementing Ising machines. Quantum annealing approaches21 using qubits offer the possibility of exponential speed up  but require cryogenic cooling. Besides cost, this requirement also restricts the type of applications where this approach would be practical. At the classical end, Ising machine implementations can be classified into the optical domain—using optoelectronic oscillators to design Coherent Ising Machines (CiM)25, and the electronic domain using a variety of classical spin implementations. CiMs offer advantages such as speed as well as a relatively broad dynamic range for the implementation of weights26. However, such implementations have traditionally been bulky, requiring long optical fibers, although there is some recent work on monolithic integration29.There is a full pallet of hardware technologies31, that digitally emulates the Ising model33 and the actual implementation of the dynamical system38. While the former approach essentially minimizes the Ising energy using a heuristic iterative approach, the latter method (relevant to this work) uses the hardware as classical spins and maps the energy minimization in the hardware directly for minimization of the Ising Hamiltonian. Various devices such as oscillators46 and ZIV diodes47 have been experimentally demonstrated as classical Ising spins. More recently, CMOS-based (bi-stable) latches have also been theoretically shown to behave as Ising spins as well48. Here, we experimentally demonstrate CMOS-latches as highly scalable and compact Ising spins. Additionally, in all of the electronic designs, the implementation of the coupling network continues to be a significant challenge for scaling. To address this, we propose to exploit the non-volatile behavior of CMOS-compatible FeFET memory arrays  to implement the interaction among the spins (CMOS latches). Consequently, our work enables a pathway to a compact Ising platform 48 wherein the energy function for a resistively coupled system of latches was shown to map to the Ising Hamiltonian. The Ising Hamiltonian is given by ij = + 1) and negative (Jij = -1) coupling over 100 runs; the details of the setup used in the experiments are discussed in supplementary note 1. It can be observed that the latches settle to the same voltage output level , when positively coupled, and opposite voltage levels , when negatively coupled. We note, however, that the exact output  shows statistical behavior, as expected. Moreover, the skew in the statistical behavior likely arises from the mismatch in the coupling resistances; although the correct ground state is attained, one configuration of the ground state is preferred over the other one.We first focus on experimentally evaluating the behavior of CMOS latches as classical spins with simple resistive coupling. The theoretical foundation for the latch-based Ising machine was elegantly formulated by J. Roychowdhuryentclass1pt{minimaBuilding on this coupled two-latch spin system, we evaluate the dynamics of a system of four negatively coupled latches as shown in Fig. 1 = L3 = VDD (+ 1); L2 = L4 = 0 V (− 1)] correspond to the two sets created by the MaxCut . Next, we experimentally evaluate the (Max)Cut on graphs of up to 10 nodes. Figure When powered up, the latch outputs [LT (high conductance) state would correspond to Jij = ± 1 whereas the high VT (low conductance) state would correspond to Jij = 2-based FeFETs used in this work; the devices are fabricated  using a programming pulse of magnitude + 4 V and a period of 1 µs. We test the interaction induced by the FeFETs among the latches by intentionally programming them into the ‘incorrect’ state, in order to observe the system evolve into the correct state i.e., when Jij = − 1 (+ 1), the latches are initialized into the same (opposite) states (0/VDD), and subsequently, it is observed whether the system evolves to the correct state. During the initialization of the latches, the FeFETs are maintained at VGS = − 0.5 V. This reduces the conductance of the FeFETs without affecting the threshold voltage. After the latches are initialized, the gate voltage is increased to VGS = 1.5 V, and the corresponding dynamics of the FeFET coupled CMOS latches are evaluated. We note that VGS = 1.5 V was required to achieve the desired level of conductance from the FeFET-based coupling element (coupling strength) since the threshold voltage of the device has not been optimized for this application. The gate voltage can be reduced to zero by appropriately adjusting the threshold as considered in the following simulations and a detailed study of the optimization and the effect of the finite FeFET output conductance will be undertaken in future work. Figure ij = + 1 , respectively.We subsequently characterize the behavior of the FeFET as a programmable coupling element in a two-latch system. To evaluate this, the FeFETs are first programmed into the low Vij = − 1), required to solve the MaxCut problem using the Ising model  is also considered; furthermore, the impact of the increased threshold voltage is detailed in supplementary note 3. Additionally, for the interconnect routing in the FeFET array, a line-to-ground capacitance of 0.122 fF/µm and 0.109 fF/µm, and a line-to-line capacitance of 0.0229 fF/µm and 0.0217 fF/µm are considered for the two metal layers- M1 and M2, respectively44. A random noise source, available in the spice stimulus53, of a maximum amplitude of 50 mV is added to the supply voltage.The above array is simulated using the HSPICE platformW/2) bias scheme  pulse is applied to all the WLs ensuring that all the FeFETs are initialized to the high-VT (low conductance) state. Subsequently, a column-wise write scheme is used wherein all the FeFET cells corresponding to Aij = 1 (in the respective column) are programmed into the low-VT (high conductance) state; no programming is required for the FeFETs that represent to Aij = 0 since the whole FeFET array was initialized into the high VT (low conductance) state at the start, as discussed earlier. Programming the FeFETs into the low-VT (high conductance) state is achieved by asserting the word line to + 3 V and the corresponding BL and SL to 0 V. The column-wise programming scheme as well as the applied voltages are selected such that the half-selected cells in the corresponding column and row experience minimal program disturbs  Execution phase: Once the FeFET array has been programmed to represent the input graph, the latches are powered on, and connected to the rows and columns of the FeFET array. The FeFETs now act as coupling elements among the latches. Subsequently, the coupled system evolves towards the ground-state energy- manifested as certain latches changing their state, and in the process, computing the solution to the MaxCut problem. Considering the statistical nature of the computation, wherein the system can get trapped in local minima , the power supply to the latches and the enable signal to the switches interfacing the latches and the FeFET array are cycled five times. Such periodic cycling is done to facilitate the system’s evolution through multiple trajectories through the phase space, and consequently, increase the probability of finding the global minima. However, we note that the size of the graph and the resulting complexity of the phase space will impact the number of cycles required to achieve a high-quality solution, which will be a critical factor for evaluating the scalability of the proposed implementation.out1 = Vout3 = VDD; Vout2 = Vout4 = 0) represents the two sets created by the MaxCut of the input graph . For the larger 25 and 50-node graphs, since the convergence time exceeded the BiqMac solver’s run-time limit, we compare our results with the heuristic manifold optimization55 algorithm. We observe that for smaller graphs (10 nodes) optimal solutions are obtained in 9 out of the 10 cases. However, the solution quality degrades (mean accuracy for the 50 node graphs is 94%) as the graph size is increased owing to the increasing complexity of the solution space- a feature observed in all Ising machine implementations.Subsequently, we evaluate the dynamics of the proposed array using numerous (30) graph instances of varying sizes up to 50 nodes; 10 randomly instantiated graphs are considered for each graph size. The entire two-stage process including the programming of the FeFETs is simulated in each case, and hence the simulations are computationally intensive. We also observe that in all the evaluated instances, the latches settle to a steady-state within 100 ns after the transmission gates are turned ON. Figure 43. We also acknowledge that the present design considers only a subset of graphs i.e., unweighted graphs, and has been evaluated here for negative Jij coefficients only (since they are relevant to solving the MaxCut problem). Nevertheless, these results motivate future work into the feasibility of this approach for solving weighted graphs (preliminary simulations shown in supplementary note 5) that can potentially exploit the multi-bit operation of the FeFET—a task that requires co-optimization of the FeFET array at the materials, device, and circuit level59.Figure In summary, this work marks the first step towards proposing an Ising machine implementation that is well-positioned to take advantage of the maturity of the CMOS process technology making it a promising design approach for realizing high-performance application-specific accelerators for solving combinatorial optimization problems.2/SiO2/p-Si gate stack, which is integrated on the 28 nm node high-κ metal gate CMOS technology platform on 300 mm silicon wafers. Detailed information is described elsewhere50. For the ferroelectric gate stack, a thin SiO2 interfacial layer is grown first, followed by the deposition of the doped HfO2 film. Then a TiN metal gate electrode was deposited using physical vapor deposition and following that the poly-Si gate electrode is deposited. The source and drain n + regions were formed by phosphorous ion implantation and then rapid thermal annealing at ~ 1000 °C. This step also results in the formation of the ferroelectric orthorhombic phase within the doped HfO2.FeFETs employed in this work have a poly-crystalline Si/TiN/doped HfOSupplementary Information.


How bone marrow niches regulate leukemogenic activities of leukemia-initiating cells (LICs) is unclear. The present study revealed that the metabolic niche component, ATP, efficiently induced ion influx in LICs through its ligand-gated ion channel, P2X1. P2X1 deletion impaired LIC self-renewal capacities and resulted in an approximately 8-fold decrease in functional LIC numbers in a murine acute myeloid leukemia (AML) model without affecting normal hematopoiesis. P2X1 phosphorylation at specific sites of S387 and T389 was essential for sustaining its promoting effects on leukemia development. ATP-P2X1-mediated signaling upregulated the PBX3 level to transactivate BCAT1 to maintain LIC fates. P2X1 knockdown inhibited the proliferation of both human AML cell lines and primary cells. The P2X1 antagonist sufficiently suppressed AML cell proliferation. These results provided a unique perspective on how metabolic niche factor ATP fine-tunes LIC activities, which may benefit the development of strategies for targeting LICs or other cancer stem cells. Acute myeloid leukemia (AML) is the most severe hematological malignancy and most commonly found in adults with high recurrence rates and mortality . LeukemiIncreasing evidence shows that bone marrow niches play important roles in AML development , 8. Many+, K+ or Ca2+, and ATP is the only known ligand for P2Xs, which are widely expressed in solid and hematological cancers [Adenosine triphosphate (ATP) mainly exists in cells and serves as a main energy carrier to support their biological behaviors. Various types of cells  also release ATP into the extracellular environment and contribute to many physiological and pathological activities , 14. The cancers , 18. P2X cancers .P2Xs have multifaceted roles in normal hematopoiesis or hematopoietic disorders. For example, P2X1 and P2X4 may be involved in the regulation of several fates of hematopoietic stem cells (HSCs) , 21. P2XP2X1 is a nonselective ATP-gated and rapidly desensitizing ion channel expressed on smooth muscle cells , plateleWe recently demonstrated that ATP-P2X7-mediated signaling enhances AML development via the CREB-PHGDH pathway. Moreover, we noticed that several P2X members, except P2X7, such as P2X1, 4 and 5, were highly expressed in human AML samples, and P2X1 ranked top among them . HoweverP2x1 mRNA levels in immunophenotypic Lin–Sca-1+c-Kit+CD34-Flt3- LT-HSCs and Mac-1+c-Kit+ LICs or Lin–Sca-1+c-Kit+CD34+CD16/CD32+ L-GMP cells  and transcription factors  that have been reported to be involved in the regulation of LIC activities from RNA-sequencing data. Interestingly, several genes, including Bcat2, Bckdhb, Bcat1, Hoxa9, Meis1, Ccnt1, Pbx3, Rora and Pbx1, were significantly decreased in P2x1-null LICs  or Hoxa9, Ccnt1, Pbx1, Rora and Pbx3  were significantly reduced in P2x1-null LICs  of AML cells were indeed decreased in the P2x1-null LICs, whereas the differentiation gene expression signatures  were increased  , U937 (M5) and MV4-11 (M5) cells  Fig. . P2X1 walls Fig. . AML celNAs Fig.  and demolls Fig. . An in vood Fig.  and prolood Fig.  comparedP2X1 among non-LICs, total AML cells, normal HSCs, normal-non-HSCs and normal total hematopoietic cells  in normal tissues, but they can be increased up to micromolar levels in many pathological states , 43. AltIn the present study, we demonstrated that P2X1 served as an oncogene to enhance LIC self-renewal. However, the roles of P2X1 in other AML types or other leukemia types remain to be further investigated. Interestingly, we showed that P2X1 knockdown in several human primary leukemia cell lines from other FAB-AML types also led to a significant delay in cell proliferation, indicating that P2X1 may exert its oncogenic effects on a variety of cancer types. P2X1 has been reported to enhance mitochondrial activities in T-cell acute lymphoblastic leukemia (T-ALL) cells . ConsistP2X1 has been reported to be basally phosphorylated at multiple sites, and it has a conserved intracellular protein kinase C (PKC) motif of TXK/R at the amino terminus , 52. PhoAlthough relapse and drug resistance commonly occur, chemotherapy is still the major treatment for AML in the clinic to date. We have previously shown that inhibition of P2X7 by its specific antagonist (A-740003) efficiently delays AML development . In the P2x1-knockout (KO), P2x4-knockout (P2x4-KO) and P2x5-knockout (P2x5-KO) mice in a C57BL/6 background were generated at the Animal Core Facility at the School of Basic Medicine, Shanghai Jiao Tong University School of Medicine. C57BL/6 CD45.2 and NOD-SCID mice were ordered from Shanghai SLAC Laboratory Animal Co. Ltd and maintained at Animal Core Facility at Shanghai Jiao Tong University School of Medicine. All animal experiments were approved and conducted according to the Guidelines for Animal Care at Shanghai Jiao Tong University School of Medicine. All the other information related to the Methods is in the Supplementary Data file.The CD45.1 mice were provided by Dr. Jiang Zhu at Ruijin Hospital, Shanghai, China. The SUPPLEMENTARY MATERIALSUPPLEMENTARY MATERIAL