APY29

APY29 inhibits IRE1α autophosphorylation (IC50 = 280 nM) and activates IRE1α ribonuclease activity. APY29 occupies IRE1α's kinase ATP-binding site to activate RNase-mediated XBP1 mRNA splicing even without upstream endoplasmic reticulum stress. It dose-dependently reduces IRE1α kinase autophosphorylation in vitro with IC50 ~0.28 μM. As dysregulation of the UPR has been implicated in a variety of cell degenerative and neoplastic disorders, small molecule modulators of IRE1α, such as APY29, serve as useful tools to understand the UPR's role in pathophysiology and to develop drugs for endoplasmic reticulum stress-related diseases.