One of four kinases that respond to cellular stress by deactivating the eukaryotic initiation factor 2 (eIF2) or other signal transduction cascades is the protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK). In order for pancreatic beta-cells to develop, differentiate, and perform properly, PERK must be highly expressed in those cells.
A type I ER membrane protein called PERK has a transmembrane segment, a cytosolic kinase domain, and a stress-sensing domain that faces the ER lumen. The stress-sensing domain of PERK releases ER chaperones in response to an increase in unfolded proteins in the ER, which activates PERK via oligomerization and autophosphorylation at numerous serine, threonine, and tyrosine residues. When PERK is activated, it phosphorylates eIF2 at serine 51, turning it into an inhibitor of the ribosome translation initiation complex and lowering total protein synthesis as a result. The ER burden is lessened by the decrease in translation, giving the cell more time to process or degrade the accumulating unfolded proteins and reestablish ER homeostasis. Although there is a reduction in overall protein synthesis, there is a specific increase in the translation of some mRNAs, such as ATF4, which affect cellular survival pathways and improve UPR activity. Cancer cells may experience apoptosis or tumor growth inhibition if their ability to thrive in hypoxic or nutrient-deficient environments is inhibited by PERK function.
|GSK2606414 is a novel, potent and selective inhibitor of PERK (PRKR-like endoplasmic reticulum kinase or protein kinase R (PKR)-like endoplasmic reticulum kinase) with an IC50 of 0.4 nM and at least 100-fold selectivity over the other EIF2AKs tested.
|GSK2656157 (GSK-2656157) is a novel, potent, ATP-competitive and highly selective inhibitor of PERK (PRKR-like endoplasmic reticulum kinase or protein kinase R (PKR)-like endoplasmic reticulum kinase) enzyme with IC50 of 0.9 nM in cell-free assays, it has 500-fold greater activity against a panel of 300 kinases.
|ISRIB, the trans-isomer of ISRIB, is a novel, potent and selective inhibitor of PERK (PRKR-like endoplasmic reticulum kinase or protein kinase R (PKR)-like endoplasmic reticulum kinase) with IC50 of 5 nM.
|Salubrinal is a novel, potent,cell-permeable and selective inhibitor of eIF2α (eukaryotic translation initiation factor 2 subunit α) dephosphorylation with potential anticancer activity.