Cells maintain precise intracellular Ca2+ and PIP levels via the actions of a complex system of Ca2+ channels, transporters, Ca2+ ATPases, and signaling effectors, including specific lipid kinases, phosphatases, and phospholipases. Recent research has shed light on the complex interplay between Ca2+ and PIP signaling, suggesting that elevated intracellular Ca2+ levels negatively regulate PIP signaling by inhibiting the membrane localization of PIP-binding proteins carrying specific domains, such as the pleckstrin homology (PH) and Ca2+-independent C2 domains. This dysregulation is often associated with cancer and metabolic diseases. PIPs recruit various proteins with PH domains to the plasma membrane in response to growth hormones, which activate signaling pathways regulating metabolism, cell survival, and growth. However, abnormal PIP signaling in cancer cells triggers consistent membrane localization and activation of PIP-binding proteins. In the context of obesity, an excessive intracellular Ca2+ level prevents the membrane localization of the PIP-binding proteins AKT, IRS1, and PLCδ via Ca2+-PIPs, contributing to insulin resistance and other metabolic diseases. Furthermore, an excessive intracellular Ca2+ level can cause functional defects in subcellular organelles such as the endoplasmic reticulum (ER), lysosomes, and mitochondria, causing metabolic diseases. This review explores how intracellular Ca2+ overload negatively regulates the membrane localization of PIP-binding proteins.Intracellular calcium , which selectively recruit certain signaling proteins to the cell membrane for activation. This process is directly involved in modulating metabolic activity. Byung-Chul Oh, Gachon College of Medicine, Incheon, South Korea, reviews how PIP-based signaling is influenced by disturbances in a second pathway regulating calcium ion flux. After reviewing the two signaling pathways, the author notes that abnormally elevated calcium ion levels in cells generate a stress response that can contribute to obesity and diabetes. Oh highlights evidence that this increased calcium creates conditions that actively impede the recruitment of PIP-binding proteins to the cell membrane, further fueling cardiovascular and metabolic dysfunction. PIPs are widely recognized as essential regulators of many biological and cellular processes that broadly impact nearly all aspects of membrane function and dynamics. Reversible phosphorylation and dephosphorylation of the PIP inositol ring by PIP kinases and phosphatases, respectively, generate seven biologically distinct phosphoinositide species4: PI(3)P, PI(4)P, PI(5)P, PIP2, PIP2, PIP2, and PIP3. PIP kinases catalyze phosphorylation at positions 3, 4, or 5 of the inositol ring of PIP, whereas lipid phosphatases such as phosphatase and tensin homolog on chromosome 10 (PTEN) and SH2-containing inositol 5′-phosphatase (SHIP) catalyze dephosphorylation at positions 3 or 5 of the PIP inositol ring5. Thus, lipid kinases and phosphatases precisely regulate the turnover of these seven interconvertible PIPs at dedicated membrane compartments in response to insulin, growth factors, and cytokines8. These seven PIPs are lipids in which proteins dock, which is mediated through specific PIP-binding domains9, including the pleckstrin homology (PH); C2; AP180 N-terminal homology (ANTH); phox homology (PX); Bin, amphiphysin, and Rvs (BAR); Fab1, yoTb, vac1, and eeA1 (FYEV); β-propeller that binds phosphoinositides (PROPPIN); and epsin N-terminal homology (ENTH) domains. Recognition of signaling proteins with PIP-binding domains by specific PIPs is essential for many cellular processes, including cell proliferation, vesicle trafficking, and homeostasis maintenance.Phosphoinositides (PIPs) are critical signaling lipids in the cytoplasmic leaflet of eukaryotic membranes2 or PIP3, which are transiently generated by phosphatidylinositol (PI) 3-kinase (PI3K)10 in response to insulin, growth factors, and cytokines. In addition, insulin- or growth factor-stimulated PI3K products are critical for signal-dependent membrane recruitment of the PH domain-carrying several kinases, such as protein kinase B (AKT), Bruton’s tyrosine kinase (BTK)12, interleukin-2-inducible T-cell kinase (ITK)13, and general receptor for phosphoinositide 1 (GRP1)14, in response to hormone and cytokine stimulation. Mutations in the PH domain that disrupt PIP2 or PIP3 binding have been reported to cause severe signaling defects such as those causing X-linked agammaglobulinemia in humans and X-linked immunodeficiency in mice15. In contrast, PH domain mutations that promote constitutive plasma membrane localization of AKT can cause cancer16. These studies suggest that membrane localization of PH domains through the specific recognition of PIP3 is crucial for signal transduction. Moreover, dephosphorylation of PIP3 via phosphoinositide phosphatases7, such as PTEN and SHIP2, transiently attenuates PIP3 binding specificity and affinity for PH domains. The orchestrated binding of PH domains to PIPs is critical for insulin-stimulated membrane targeting and signal transduction.Among PIP-binding domains, PH domains are effectors that recognize the lipid second messengers PIP2+ is a universal and versatile signaling molecule that controls many cellular processes, including muscle contraction, neurotransmission, hormone secretion, organelle communication, cell metabolism, and cell growth17. Given the versatility and diversity of Ca2+ functions, intracellular Ca2+ homeostasis is tightly regulated by spatiotemporally coordinated interactions of plasma membrane channels and transporters, as well as ER and mitochondrial Ca2+ transporters and pumps21. Thus, dysregulation of Ca2+ channels, pumps, and transporters in the plasma membrane, ER, and mitochondria has been shown to play an essential role in insulin resistance in diabetes and obesity24. Furthermore, obesity-induced ER dysfunction leads to Ca2+ depletion from ER stores and activation of ER stress and the unfolded protein response (UPR)26. Chronic Ca2+ depletion in the ER results in intracellular and mitochondrial Ca2+ overload27, which may further exacerbate mitochondrial dysfunction, such as a reduction in mitochondrial adenosine triphosphate (ATP) production and increased mitochondrial reactive oxygen species (ROS) production28.Intracellular Ca2+ and PIPs are versatile signaling molecules associated with many regulatory cellular pathways. Although the mechanistic details of Ca2+ and PIP coupling are only now beginning to be understood30, it is evident that through crosstalk, synergy, and negative feedback mechanisms, intracellular Ca2+ fine-tunes PIP signaling to mediate complex metabolic responses. Although alterations in intracellular Ca2+ homeostasis have been shown to be key pathophysiological events in insulin resistance, obesity, and type 2 diabetes, we discuss the molecular mechanism underlying intracellular Ca2+-mediated inhibition of PH-domain-carrying protein targeting the plasma membrane. We will also discuss the potential role of intracellular Ca2+ as a contributing factor to the inhibition of PIP signaling, especially signaling mediated through the targeting of C2 and PH domain–carrying proteins to the membrane. Throughout this review, we highlight the expression and function of various Ca2+ channels, pumps, and transporters in the plasma membrane, ER, and mitochondria and describe their roles in the pathogenesis of metabolic diseases.Ca9. This versatility of PIPs is a result of the chemistry of the myo-inositol moiety, which is attached to diacylglycerol (DAG) via a diester phosphate at the D-1 position, with five free hydroxyls occupying the other ring positions. Hydroxyl groups in the inositol ring at positions 3, 4, and 5 are phosphorylated or dephosphorylated by lipid kinases and phosphatases, respectively, generating seven distinct PIP species, PI(3)P, PI(4)P, PI(5)P, PIP2, PIP2, PIP2, and PI3 , homology-Bin-Amphiphysin-Rvs (F-BAR), four-point one, ezrin, radixin, and moesin (FERM), FYVE, PH, PX, ENTH/ANTH, Tubby, and PROPPINs31. These domains function as docking sites through which signaling proteins are targeted for transport to specific subcellular locations and might directly regulate protein function. In addition to PH domains, many other domains, including ANTH, PX, BAR, FYEV, PROPPIN, and ENTH domains, interact with various PIPs and are reviewed elsewhere2.The primary acidic phospholipids in mammalian cell membranes are phosphatidylserine, phosphatidic acid, and phosphatidylinositol (PI) phosphate. PIPs constitute only a small fraction of cellular phospholipids derived from PI but control most aspects of cell physiology36. The PH domain comprises approximately 120 amino acids and can bind PIPs, which mediate intracellular signaling, trafficking, and regulation37. The crystal structures of several PH domains have revealed how they recognize the phosphate groups in PIPs and anchor them through electrostatic interactions via positively charged side chains38. Based on in vitro and in vivo assays, PH domains can be classified as showing specific and high affinity or broad and low affinity for PIPs39. PH domains are important effectors for the phospholipid second messengers PIP2 and PIP3. These second messengers are transiently generated by cell surface receptor-stimulated PI3K activation following insulin, growth factor, or cytokine stimulation3. Therefore, the PH domains of kinases downstream of PI3K, such as AKT32, BTK12, ITK13, and GRP114, recognize either PIP2, PIP3 or both with remarkable specificity and affinity. This precise recognition of the PI3K products PIP2 and PIP3 by PH domains is crucial for signaling-dependent membrane recruitment of kinases such as AKT, BTK, ITK, and GRP1 in response to hormone and cytokine stimulation40. In addition, the PH domain of PLCδ specifically recognizes membrane PIP235 P, PI(4)P, PI(5)P, or PIP2 play essential roles in the membrane localization of PH domain-carrying proteins34.PH domains are small protein modules found in major regulators of vesicle biogenesis and are thus involved in intracellular trafficking; the proteins carrying these domains include pleckstrin, the AKT/RAC family serine/threonine kinases, Btk/Itk/Tec subfamily nonreceptor tyrosine kinases, NrKA/NrKB protein kinases, the breakpoint cluster region protein (BCR), the Rho/Rac guanine nucleotide exchange factor FGDs, insulin receptor substrates (IRSs), PLCs, the Rho family of guanosine triphosphatases (GTPases), the Ras GTPase-activating protein (RasGAP), oxysterol-binding proteins, ceramide kinase, G protein receptor kinases, Src homology 2B (SH2B) adapter proteins involved in tyrosine receptor kinase family member binding, KIF1A, and ADP-ribosylation factors (ARFs)42 P343, which recruits cytosolic and inactive AKT, a key downstream effector, to the plasma membrane through the AKT PH domain4. This action leads to the phosphorylation and activation of AKT by phosphoinositide-dependent protein kinase 1 (PDK1) and mammalian target of rapamycin (mTOR) complex 2 (mTORC2)44. Activated AKT functions as a key convergence point in the PIP3-mediated insulin signaling pathway by phosphorylating the GTPase-activating protein AKT substrate of 160 kDa (AS160), cyclic AMP (cAMP) response element-binding protein (CREB), the enzyme glycogen synthase kinase 3β (GSK3β), forkhead transcription factors (FOXOs), sterol regulatory element-binding protein (SREBP), and tuberous sclerosis complex 2 (TSC2)42. Once activated, AKT phosphorylates and inactivates GSK3β, which leads to the activation of glycogen synthase, a major substrate of GSK3, resulting in glycogen synthesis45. Active AKT stimulates glucose uptake in the liver via the phosphorylation of the GTPase-activating protein AS160, which is critical for the translocation of glucose transporter 4 (GLUT4)-carrying vesicles to the plasma membrane46. AKT also regulates cell survival by inhibiting several proapoptotic factors, including proapoptotic Bcl-2 protein (BAD)47. Moreover, AKT phosphorylates and directly inhibits FOXO transcription factors48, which are sequestered in the cytoplasm via their interactions with 14-3-3 proteins to inhibit gluconeogenesis and autophagy in the liver. Insulin signaling induces fatty acid and cholesterol synthesis by regulating SREBP transcription factor activity49. AKT effectively activates the mTOR pathway through its phosphorylation of TSC1/2, a negative regulator of mTOR. Thus, AKT-activated mTOR stimulates protein synthesis by phosphorylating p70 ribosomal protein S6 kinase (p70S6K) and eukaryotic translation initiation factor 4E binding protein 1 (4EBP1)50 P2 to yield PIP2 and PIP3. The cellular concentrations of PIP2 and PIP3 are modulated by two types of inositol-specific phosphatases in the cell: PTEN and SHIP1 and SHIP27. PI3K signaling is attenuated by PTEN, which dephosphorylates the 3-phosphate in PIP2 and in PIP3 to generate PI(4)P and PIP2, respectively. Ultimately, PTEN decreases plasma membrane PIP2 and PIP3 levels, which drives insulin signaling. PTEN eliminates docking sites for recruited downstream PH domain-carrying effector proteins that engage with the PI3K products PIP2 and PIP3. Thus, PTEN suppresses PI3K-stimulated ATK, BTK, ITK, and GRP1 by disrupting the membrane localization of effector molecules. PTEN-deficient mice have been shown to exhibit increased insulin sensitivity and glucose tolerance in peripheral tissues51. Moreover, the knockdown of PTEN using antisense oligonucleotides reversed hyperglycemia in diabetic ob/ob mice52. In contrast, SHIP1 and SHIP2 dephosphorylate the 5-phosphate of PIP3 to yield PIP2. SHIP1 expression is exclusive to hematopoietic cells and thus plays a key role in immune system regulation. SHIP2 is widely expressed in most cells and negatively regulates insulin signaling by inhibiting the membrane localization of AKT by decreasing the PIP3 level. Mice lacking SHIP2 show increased glucose tolerance and reduced insulin sensitivity after increased glucose uptake and glycogen synthesis6, suggesting that SHIP2 is a critical negative regulator of insulin signaling and sensitivity P or PIP53 and the mitochondrial protein prohibitin (PHB)54. Following insulin treatment, OGT was translocated to the plasma membrane mediated by PIP3, inhibiting the phosphorylation of AKT. OGT and PHB physically interact55 and are phosphorylated by the insulin receptor56 and AKT57, respectively. OGT and PHB are thought to be components of protein complexes that negatively regulate insulin signaling. Moreover, AKT activity is regulated by several protein phosphatases, such as protein phosphatase-2A (PP2A) and PH-domain leucine-rich repeat protein phosphatase (PHLPP), which directly dephosphorylate and inhibit AKT activation59 ]2+ is an abundant divalent ion in the body and is primarily stored in bones. As an electrolyte, Ca2+ plays an essential role as a ubiquitous and versatile signaling molecule that regulates a wide variety of cellular processes19, including muscle contraction, neurotransmission, and hormone secretion. It also acts as an enzyme cofactor and second messenger in organelle communication, cell motility, and cell growth. Because Ca2+ exhibits critical and diverse functions, the intracellular Ca2+ concentration is tightly regulated20. The intracellular Ca2+ level is maintained at lower levels (50–100 nM) than the extracellular Ca2+ level (1–2 mM)60. Regulation of intracellular Ca2+ levels is controlled by plasma membrane channels, such as nonselective transient receptor potential (TRP) channels, purinergic ionotropic receptors (P2RXs), and voltage-activated Ca2+ (CaV) channels, and by ER and mitochondrial Ca2+ transporters and pumps, such as plasma membrane Ca2+ ATPases (PMCAs), sarcoplasmic/ER Ca2+ ATPases (SERCAs), and the mitochondrial Na+/Ca2+/Li+ exchanger (NCLX)21  and STIM2. STIMs activate ORAI and C-type transient receptor (TRPC) proteins at the plasma membrane and induce store-operated Ca2+ entry (SOCE)64, which increases the rate of intracellular Ca2+ entry from the extracellular space. After Ca2+ enters the cytosol, SERCAs pump Ca2+ into the ER to replenish the Ca2+ stores in the ER65.Ca)21 Fig. . PMCAs612+ signaling is initiated by stimuli that increase the level of intracellular Ca2+, which then regulates downstream Ca2+ signaling pathways. Except for that in neuronal cells, Ca2+ signaling in most cells is initially regulated by hormone binding to a G protein-coupled receptor (GPCR). For example, glucagon and catecholamines such as epinephrine activate the stimulatory G protein α (Gαs), leading to stimulation of adenylate cyclase, which produces cAMP66. An increase in cAMP level activates protein kinase A (PKA), which further phosphorylates and activates inositol trisphosphate receptors (IP3Rs), resulting in Ca2+ release from the ER67. Catecholamines such as norepinephrine activate Gαs and further activate PLC, which catalyzes the hydrolysis of PIP2 to produce the intracellular messengers IP3 and DAG. IP3 binds IP3Rs, stimulating Ca2+ release from the ER68.Intracellular Ca2+ activates Ca2+-dependent signaling molecules such as Ca2+ calmodulin (CaM)-dependent kinases (CaMKs)69, calcineurin70, and Ca2+dependent protein kinase C (PKC)19 , and c-Jun N-terminal kinase (JNK), which are important for metabolism, inflammation, and other cellular processes69 , myocyte enhancer factor-2 (MEF-2), nuclear factor of activated T cells (NFATc), and transcription factor EB (TFEB)70. Activated CRTC2, MEF-2, NFATc, and TFEB are translocated from the cytosol to the nucleus, where they activate the expression of target genes essential for metabolic, cardiovascular, immune, lysosome biogenesis, and autophagy functions21. When Ca2+ and DAG levels are increased in the cytosol, these proteins bind to the C2 and C1 domains of PKC, respectively; PKC is then translocated to the plasma membrane, resulting in its activation. Activated PKC phosphorylates substrates such as mitogen-activated protein (MAP) kinase, transcription factor inhibitor IκB, vitamin D3 receptor (VDR), and calpain21.A hormone-stimulated elevation in intracellular Ca)19 Fig. . CaM unds69 Fig. . An elev2+ levels: the ER and mitochondria. The plasma membrane Ca2+ ATPase (PMCA) and Na+/Ca2+ exchanger (NCX) are the two main regulators of intracellular Ca2+; both remove intracellular Ca2+ from cells21. Thus, intracellular ER and mitochondrial Ca2+ homeostasis are orchestrated by transporters and pumps, including PMCAs, SERCAs, and mitochondrial NCLX. Notably, PMCA and SERCA ion pumps require ATP hydrolysis to pump Ca2+ ions from the cytosol to the extracellular space and ER  data showed that a single-nucleotide polymorphism (SNP) in IP3R2 was associated with alterations in the waist-to-hip ratio adjusted for body mass index (BMI)72. IP3R protein levels were increased in a mouse model of obesity (db/db mice), resulting in increased intracellular Ca2+ release from the ER to the cytosol73 and CaMK activation26 y24 Fig. . These a2+ pump that is critical for maintaining a low intracellular Ca2+ level in resting eukaryotic cells. Impaired PMCA activity and reduced PMCA expression lead to intracellular Ca2+ overload and Ca2+-dependent cell death75. PMCA activity is inhibited by ROS and ATP depletion under metabolic stress conditions76. In contrast, PIP2, a major PMCA activator, increases the affinity of PMCA for ATP and that of Ca2+/CaM for an autoinhibitory motif; PMCA then increases Ca2+ movement into the extracellular space76. Importantly, a role of the PMCA pump in human metabolic disease has been suggested by a recent GWAS-related meta-analysis that revealed an SNP in the PMCA1 locus associated with alterations in type 2 diabetes and HbA1c-adjusted BMI , especially saturated palmitic acid (PA), are significantly higher in obese individuals than in healthy subjects78. Increased serum FFA levels are closely linked to obesity-associated metabolic complications80, such as insulin resistance, type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD). Numerous studies85 have shown that high PA levels induced Ca2+-mediated pathogenic changes, such as ER stress and lysosomal and mitochondrial dysfunction. High PA levels trigger aberrant ER Ca2+ release, thereby depleting ER Ca2+ stores. ER Ca2+ deficiency impairs the protein folding machinery, which leads to the UPR and accumulation of misfolded proteins. PA-induced ER Ca2+ deficiency leads to mitochondrial Ca2+ overload, reduces the mitochondrial membrane potential, and increases ROS levels in various cell types84  by various phosphoinositides, a group of signaling lipids, is of particular interest. TRPML1 activity is known to be positively modulated by PIP2, while other PIPs, such as PIP2, PIP2, and PIP3, inhibit its function, affecting the release of Ca2+ from lysosomes into the cytosol91. Under conditions such as obesity, in which the intracellular Ca2+ level is elevated, PIPs such as PIP2, PIP2, and PIP3 form Ca2+-PIPs29, which potentially counteract the inhibitory effects on TRPML1, leading to sustained release of lysosomal Ca2+ into the cytosol. Disruption of TRPML1 regulation by these phosphoinositides significantly inhibits cellular functions and may lead to various diseases.Lysosomal Ca2+ homeostasis is a key mechanism in metabolic tissues, which, in turn, leads to organelle dysfunction. In the context of obesity, the disruption of Ca2+ homeostasis in the ER and mitochondria leads to ER stress, impaired protein folding, and reduced mitochondrial functioning, including reduced mitochondrial ATP production and increased mitochondrial ROS production28. The resulting ER and mitochondrial dysfunction may trigger a vicious cycle of intracellular Ca2+ homeostasis disruption, causing the downregulation of ATP-driven Ca2+ pumps such as SERCAs and PMCAs and thus leading to intracellular Ca2+ overload P2, PIP2, and PIP3, at physiological concentrations. This binding results in the formation of Ca2+-PIPs such as Ca2+-PIP2, Ca2+-PIP2, and Ca2+-PIP3, which inhibit the electrostatic interaction between PH domains and membrane PIPs, ultimately preventing membrane targeting of PH domain-carrying proteins and disrupting insulin signaling29 P298; this interaction inhibits membrane localization of PH domain-carrying PLCδ to a membrane PIP2. In addition to the PH domain-carrying proteins, the Ca2+-independent C2C domain in PI3K-C2α is recruited to the plasma membrane by PIP2 and PIP3 under normal conditions. In contrast, higher intracellular Ca2+ levels prevent the membrane localization of Ca2+-independent C2C domain-carrying PI3K-C2α by forming Ca2+-PIP2 and Ca2+-PIP330. Additional compelling experiments confirmed that a high intracellular Ca2+ level inhibits membrane localization of the PH domain-carrying AKT and PLCδ30. These data suggest that a high intracellular Ca2+ level is important for inhibiting the membrane localization of PH domain-carrying AKT, PLCδ, and IRS1, as well as Ca2+-independent C2C domain-carrying PI3K-C2α, indicating a novel role in regulating Ca2+ and PIP-mediated signaling. Because both Ca2+ and PIPs are versatile and specific signaling factors associated with many regulatory pathways in a cell, the formation of Ca2+-PIPs when the concentration of intracellular Ca2+ is high also suggests that Ca2+ prevents membrane localization of PIP-binding proteins such as the PH domain–carrying proteins AKT, PLCδ, and IRS1 and the Ca2+-independent C2C domain–carrying protein PI3K-C2α because Ca2+ is coupled to PIPs P2 to generate PIP3. PIP3 then recruits PH domain–carrying signaling proteins, such as PDK, AKT, GTPases (such as Rac and Rho), ITK, and BTK, to the plasma membrane. These PH domain–carrying proteins are then activated at the plasma membrane and regulate a variety of cellular functions, including cell survival, proliferation, cytoskeleton rearrangement, intracellular vesicle trafficking, and cell metabolism.This review provides an overview of Ca2+ homeostasis is maintained by the actions of transporters and pumps, including PMCAs, SERCAs, and NCLX. These proteins ensure that the proper Ca2+ levels are maintained in the ER and mitochondria, organelles that play critical roles in cellular metabolism and signaling. SERCAs are located in the ER and pump Ca2+ ions into the ER compartment, while PMCAs are located in the plasma membrane and pump Ca2+ out of the cell. Moreover, studies have shown that dysregulation of SERCAs and PMCAs results in increased intracellular Ca2+ levels and alterations in Ca2+ homeostasis in various metabolic diseases, including diabetes, cardiovascular disease, and obesity. These findings highlight the importance of understanding the mechanisms involved in regulating intracellular Ca2+ levels and their effects on cellular signaling. Several compelling pieces of evidence presented herein demonstrate that our comprehension of PIPs and Ca2+ coupling is particularly important given the consequences of intracellular Ca2+ dysregulation in diverse pathological settings, including cardiovascular disease, insulin resistance, and type 2 diabetes. One important discovery in the field of PIPs and intracellular Ca2+ signaling is the role of Ca2+-mediated inhibition of the membrane localization of PIP-binding proteins such as those carrying PH domains and C2C domains, suggesting a novel mechanism by which PIP-binding proteins are regulated on the basis of the intracellular Ca2+ level. This mechanism has been shown to regulate various cellular functions, including endocytosis, intracellular trafficking, and gene expression. These findings provide new insights into the complex interplay between PIPs and intracellular Ca2+ signaling and highlight the importance of understanding these relationships for developing new therapeutic strategies for treating metabolic diseases. Because the regulation of intracellular Ca2+ and PIP signaling is a complex and dynamic process that is critical to maintaining cell signaling, disruption to these signaling processes can have unintended consequences. Therefore, it is important to carefully consider the potential risks and benefits before developing therapeutic strategies targeting these pathways in patients with obesity, diabetes, or other chronic metabolic diseases.Ca


Ca2+ acts as a secondary messenger, connecting various environmental stimuli to different biological processes, especially during stress rejoindering in plants. Even though many studies involving Ca2+ signalling in plants have been published, there have been no studies on the roles of Ca2+ signalling in herbicide stress response. Hence, this mini-review will highlight the possible sensing and molecular communication via Ca2+ signals in weeds under herbicide stress. It will also discuss some critical points regarding integrating the sensing mechanisms of multiple stress conditions and subsequent molecular communication. These signalling responses must be addressed in the future, enabling researchers to discover new herbicidal targets.The continuous use of herbicides for controlling weeds has led to the evolution of resistance to all major herbicidal modes of action globally. Every year, new cases of herbicide resistance are reported. Resistance is still in progress in many species, which must be stopped before it becomes a worldwide concern. Several herbicides are known to cause stressful conditions that resemble plant abiotic stresses. Variation in intracellular calcium (Ca Thereafter, the [Ca2+]cyt couples the extracellular stimuli to their distinctive intracellular responses and synchronize a wide range of endogenous processes. Besides increasing the concentration of the [Ca2+]cyt, sometimes these special Ca2+-binding proteins directly interact with other targets and allow them to execute their respective response  signal transduction pathway and regulates the homeostasis of cellular Na+ and K+  and Ca‐dependent protein kinase 6 (CDPK6) in Arabidopsis were found to regulate the metabolism of plant cells positively and confer cold tolerance  tends to accumulate in plants as a response to stress like high temperatures and has been extensively used as a physiological indicator to assess the intensity of stress felt by plants  and glutathione-S-transferases (GSTs). Hence, the development of herbicide resistance in grass weeds can be considered almost similar to other abiotic stresses such as temperature and drought. Weedy plants have developed several exciting mechanisms to adapt against herbicide stress. Although numerous mechanisms have been discovered, several such mechanisms, especially different signalling events, are yet to be discovered.The most basic molecular mechanisms of herbicide resistance include target-site resistance (TSR) and non-target-site resistance (NTSR). Among the TSR, genetic mutations and gene overexpression are the most prevalent mechanisms. NTSR mechanisms include enhanced metabolism, reduced absorption and translocation etc. . NTSR me2+ signalling events amend the expression patterns of several essential genes (mainly NTSR genes) in response to several biotic and abiotic stresses , glutamate receptor-like channels (GLRs), Cyclic nucleotide-gated channels (CNGCs), mechanosensitive-like channels (MSLs) and the reduced hyperosmolality-induced [Ca2+]cyt increase (OSCAs) channels. Within the plant cells, these channels are maintained precisely in an extremely synergistic manner  decodes and relays the signals for further processing . These Ca2+ binding proteins can be classified into sensor relay proteins and sensor responder proteins. The sensor responder proteins include calcium-dependent protein kinases (CDPKs), which mainly bind to these Ca2+ ions and induce conformational changes  and CBL-interacting protein kinases (CIPKs). These kinases and their specific Ca2+ binding proteins form a complex cellular network in various cellular processes  to respond and adapt to recurring stresses , the area of alternative splicing has remained unexplored in weedy plants , in general, generates multiple mRNA isoforms from the same pre-mRNA and is alleged to contribute to increasing transcriptomic and proteomic diversity . The puty plants . Althougy plants . We hypostresses . So, it proteins . For exaproteins . Moreoveproteins . As a re52+ signalling in alleviating herbicide stress. Since changes in the intracellular and cytosolic Ca2+ concentration are stimulus-specific, Jaffe posited three critical criteria to ensure that a particular Ca2+ signal pattern is associated with a particular stress response. These criteria include: (a) inhibition of the levels of Ca2+ must also impede the physiological response; (b) an artificial increase in the Ca2+ levels must provoke the physiological response, even in the absence of the stimulus; and (c) an increase in the cytosolic Ca2+ concentration must either precede or accompany the response  and Selective Plane Illumination Microscopy (SPIM). Even though FRET has been used in Arabidopsis, to our knowledge, these techniques have not been used to understand calcium signalling in any weedy plants. In addition to these Ca2+ dyes, protein-based Ca2+ indicators (such as aequorin–based and GFP–based indicators) are also used to measure Ca2+ in living plant cells  is emitted, which can be detected with a luminometer. Bioluminescent probes paired with Ca2+-sensitive aequorin can be used in the weeds for real-time measurement of the Ca2+ signal patterns linked with herbicide stress. In addition to the aequorin-based Ca2+ sensors, since their discovery in 1997, the GFP-based Ca2+ indicators have also gained the interest of plant biotechnologists  will be very useful in identifying the candidate Ca2+ transducing proteins, channels, exchangers and pumps involved in weed-herbicide interactions and other abiotic stress responses in weeds. Weeds have developed resistance against all the major herbicidal modes of action. Hence, further genetic engineering of these stress-specific Ca2+-signalling regulators might enable the herbicide industries to discover novel targets and use them for herbicide discovery. Research on weed molecular communication during herbicide stress  is still in its infancy. This area of research should be an exciting area for future research in terms of novel and applied science.Despite extensive research on the mechanisms of herbicides in recent years, the mechanisms of herbicides and the herbicide stress signalling network have not been investigated and discovered. Much progress has been made in understanding several Ca drought . Similar drought . Hence,  drought . Several drought . In thisThe original contributions presented in the study are included in the article/MS and AR conceived the idea. MS, KH, RB and PK drafted the manuscript. MS and RAC designed and created the figure. AR and JS edited the manuscript MKS revised the manuscript. All authors contributed to the article and approved the submitted version.


ALDH1A1 on average significantly overexpressed in the poor prognosis group at the RNA level, but its protein product, ALDH1A1 protects acute myeloid leukemia cells from lipid peroxidation byproducts. This capacity to protect cells can be ascribed to the stability of the enzyme under conditions of oxidant stress. The capacity to protect cells is evident both in vitro, as well as in mouse xenografts of those cells, shielding cells effectively from a number of potent antineoplastic agents. However, the role of ALDH1A1 in acute myeloid leukemia has been unclear in the past due to evidence that normal cells often have higher aldehyde dehydrogenase activity than leukemic cells. This being true, ALDH1A1 RNA expression is significantly associated with poor prognosis. It is hence imperative that ALDH1A1 is methodically targeted, particularly for the acute myeloid leukemia patients of the poor prognosis risk group that overexpress ALDH1A1 RNA.The protein family of aldehyde dehydrogenases (ALDH) encompasses nineteen members. The ALDH1 subfamily consists of enzymes with similar activity, having the capacity to neutralize lipid peroxidation products and to generate retinoic acid; however, only ALDH1A1 emerges as a significant risk factor in acute myeloid leukemia. Not only is the gene  In survival .A high expression of ALDH1A1 in AML cells would be a selective advantage: (a) the enzyme is relatively resistant to inactivation from byproducts of lipid peroxidation, (b) it detoxifies a broad range of aldehyde substrates, particularly long-chain , (c) facALDH1A1 RNA expression and poor prognosis in AML [Increased levels of malondialdehyde, for example, will cause senescence in the tissue microenvironment, while ALDH1A1-overexpressing AML cells survive, switching readily from their inflammatory state to reactivate DNA repair, and remaining capable to cause disease relapse. In AML, a general drop in ALDH1A1 expression in tissue could coincide with the loss of normal progenitor cells; however, AML stem cells overexpressing ALDH1A1 gain an advantage: on the one hand it protects directly from antineoplastic agents, and on the other hand it reactivates DNA repair, by removing toxic aldehydes that inactivate repair enzymes . AML cels in AML .To summarize in a concept, initial conditions for AML leukemogenesis would entail a senescent microenvironment with a general deficit in detoxification enzymes, including ALDHs. During progression to advanced AML, increased oxidant stress in the microenvironment, possibly also combined with toxic effects of antineoplastic treatment, select for clones of malignant cells that are resistant to oxidant stress and simultaneously possess the highest leukemia-initiating potential. ALDH1A1 is expected to reach a higher-than-average activity in those leukemia stem cell clones, which thrive under conditions that are toxic to other AML cells. At the same time, oxidant stress elicits changes in the physiology of the affected tissue, which lead to an adverse disease outcome .From all of the above, it can be concluded that for patients who belong to the high-risk group, a strategy is needed to neutralize the key factors that provide a selective advantage to leukemia-initiating cell clones. Especially important is the choice of conditions that have the least toxic impact on normal hematopoietic stem cells.At the heart of this choice is the use of inhibitors for NFκB: either directed on the NFκB complex itself or directed to either upstream and downstream signaling cascades. Direct inhibition of NFκB is achieved by interaction with the glucocorticoid receptor: glucocorticoids indeed have shown activity both against chemoresistant AML cells and also as a clinical treatment for hyperleukocytosis in AML, which is characterized by massive entry of leukemic blasts in peripheral blood ,128,129.FLT3ITD from the criteria of patient inclusion to the poor prognosis risk group, in the new, ELN 2022 guidelines: the FLT3ITD allelic ratio is no longer considered in the risk classification; consequently, AML with FLT3ITD (without adverse-risk genetic lesions) are now categorized in the intermediate-risk group, irrespective of the allelic ratio [The use of upstream inhibitors, such as the multikinase inhibitor midostaurin, which in addition to FLT3 inhibits other tyrosine kinases, has proven relatively effective for primary AML ,131,132.ic ratio .TP53 [The use of downstream inhibitors for the NFκB signaling cascades has proven at least as effective as upstream inhibitors. Specifically, the BCL2 inhibitor venetoclax shows as promising as previously proteasome inhibiting agents ,134,135.TP53 . This leTP53 . While vSingle-agent clinical studies have shown that even the molecule obatoclax, which inhibits both BCL2 as well as its related apoptosis regulator MCL1, is alone not effective in AML, apparently due to the diversity of antiapoptotic mechanisms that AML cells may employ . One sucIn this context, ALDH1A1 and HLTF (helicase-like transcription factor) levels seem to be important in the response of cells to hydroxychloroquine (HCQ). In this scenario, HCQ-sensitive cells have high ALDH1A1/low HLTF or low ALDH1A1/low HLTF expression patterns but HCQ-resistant cells have a low ALDH1A1/high HLTF expression pattern . ALDH1A1On the same note, oxidative stress and the ensuing lipid peroxidation have critical effects on various cellular mechanisms and an inhibitory role in autophagy by causing lysosomal dysfunction . In thisA recently identified mediator for ALDH1A1-induced resistance of lung adenocarcinoma cells to tyrosine kinase inhibitors was GPX4 (glutathione peroxidase 4) . This isThe selective advantages offered to AML cells by ALDH1A1 under conditions that are detrimental to host tissue can be curtailed by targeting their underlying mechanisms, especially those that pertain specifically to malignant cells. Given that the malignant cells thrive under oxidant stress that switches OGG1 to an NFκB-augmenting factor, the inhibition of this circuit by the compound TH5487 would hamper the interaction of AML cells with their microenvironment .ALDH1A1 expression, although retinoic acid receptor alpha acted as an activator: its partnering activator of the ALDH1A1 promoter, namely C/EBPβ, was repressed by retinoic acid [Retinoic acid was proposed as an AML treatment that would decrease ALDH1 activity . In factoic acid . Thus atALDH2 also has a significant association with unfavorable patient risk, when expression data from over 1000 patients of six leading AML studies were analyzed [A drug with established broad in vitro activity against neoplastic cells is disulfiram; this drug inhibits multiple pathways, which also include ALDHs . A high-analyzed ; thus, bIn vivo, the half-life of disulfiram is highly variable and is at best expected to range between 7 and 8 h ,166,167.Taken together, a number of mechanisms allow AML cells to survive antineoplastic treatment. In the physiological context, ALDH1A1 is expressed during recovery from inflammation as a mechanism to protect recruited progenitor cells from oxidant stress. The recruited progenitor cells subsequently activate tissue regeneration cascades. The same mechanism that protects essential progenitor cells from oxidant stress, functions in AML to protect leukemia stem cells from byproducts of treatment-induced oxidant stress.In AML, certain cell subpopulations, and especially leukemia-initiating cells, may adapt to a number of drugs by expressing appropriate proteins that confer drug resistance. In particular, ALDH1A1 enables cancer progression by facilitating drug resistance and fostering resilience of tumor-initiating cells; this applies to cancers driven by RAS/NFκB, FLT3ITD, and mutant P53. On the one hand, this suggests using more than one agent to treat AML, and on the other hand, it suggests monitoring critical mediators of AML treatment resistance, to treat patients accordingly.The main reason that the ALDH1 role in drug resistance of AML has not been addressed in the clinic, is the prevalence of AML cells with low ALDH1 activity, which made it difficult to understand the dynamic nature of ALDH impact during disease progression. Chemotherapy elicits cellular stress and eliminates sensitive AML clones while selecting clones of therapy-resistant cells. Resistant AML cells give rise to recurrent disease. Disease relapse is thereby driven by cell clones that operate metabolic pathways which allow them to adapt to cellular stress. To kill resistant AML clones, therapeutic intervention needs to interfere with mechanisms of cell stress resistance: one such mechanism is the expression and activity of ALDH1A1.An improved method of AML treatment thus needs on the one hand to include substances that elicit cellular stress in leukemia cells, such as conventional chemotherapeutic agents, and on the other hand to incorporate substances that inhibit the metabolic adaptation of AML cell clones to cellular stress, as we outline here.