FIELD

The present disclosure relates generally to therapeutic agents that may be useful as modulators of Integrated Stress Response (ISR) pathway.

BACKGROUND

Genetically modifying plants to express heterologous proteins or increase the expression of endogenous proteins has become an important tool for a large number of business. Plants can be modified to express an increased amount of essential amino acids, to achieve greater yields of the plants or the proteins express therein, or to produce recombinant proteins such as biopolymers, industrial proteins/enzymes, and therapeutic proteins. However, there is a need to further increase the expression of plant proteins, which may require methods other than genetic modification.

In addition, given the resistance to genetically modifying plants by some people, it may be desirable to increase protein production in plants using other methods. Increased protein production by plants will likely be essential for ensuring the availability of enough protein to feed an increasing world population under changing environmental conditions. Further, increased protein production in plants promote plant growth, because additional proteins can be released through the roots into the surrounding area to attract microorganisms, such as bacteria that can in turn improve plant development.

One potential method of increasing protein production in plants is by modulating Integrated Stress Response (ISR) pathway. Diverse cellular conditions and stresses activate this widely conserved signaling pathway. The ISR pathway is activated in response to intrinsic and extrinsic stresses, such as viral infections, hypoxia, glucose and amino acid deprivation, oncogene activation, UV radiation, and endoplasmic reticulum stress. Upon activation of ISR by one or more of these factors, the eukaryotic initiation factor 2 (eIF2, which is comprised of three subunits, α, β, and γ) becomes phosphorylated in its α-subunit and rapidly reduces overall protein translation by binding to the eIF2B complex. This phosphorylation inhibits the eIF2B-mediated exchange of GDP for GTP (i.e., a guanine nucleotide exchange factor (GEF) activity), sequestering eIF2B in a complex with eIF2 and reducing general protein translation of most mRNA in the cell. Paradoxically, eIF2α phosphorylation also increases translation of a subset of mRNAs that contain one or more upstream open reading frames (uORFs) in their 5′ untranslated region (UTR). These transcripts include the transcriptional modulator activating transcription factor 4 (ATF4), the transcription factor CHOP, the growth arrest and DNA damage-inducible protein GADD34 and the β-secretase BACE-1.

Additionally, compounds useful in modulating the ISR pathway may also be useful in treating a large number of diseases. In animals, the ISR pathway modulates a broad translational and transcriptional program involved in diverse processes such as learning memory, immunity, intermediary metabolism, insulin production and resistance to unfolded protein stress in the endoplasmic reticulum, among others. Activation of the ISR pathway has also been associated with numerous pathological conditions including cancer, neurodegenerative diseases, metabolic diseases (metabolic syndrome), autoimmune diseases, inflammatory diseases, musculoskeletal diseases (such as myopathy), vascular diseases, ocular diseases, and genetic disorders. Aberrant protein synthesis through eIF2α phosphorylation is also characteristic of several other human genetic disorders, cystic fibrosis, amyotrophic lateral sclerosis, Huntington disease and prion disease.

BRIEF SUMMARY

Modulators of the Integrated Stress Response (ISR) pathway are described, as are methods of making and using the compounds, or salts thereof.

