IRE-3 is a highly potent and selective small molecule modulator of IRE1α. Under endoplasmic reticulum stress, unfolded protein accumulation leads to activation of the endoplasmic reticulum transmembrane kinase/endoRNase (RNase) IRE1α. IRE1α oligomerizes, autophosphorylates and initiates splicing of XBP1 mRNA, thus triggering the unfolded protein response (UPR). Interestingly, IRE-3 inhibits the XBP1 mRNA splicing through binding to the IRE1α ATP-, even under endoplasmic reticulum stress. It shows dose-dependent reduction of IRE1α kinase autophosphorylation in vitro with IC₅₀~3.12 µM. IRE-3 can also block enzymatic activities of IRE1α in INS-1 rat insulinoma cell lines. As dysregulation of the UPR has been implicated in a variety of cell degenerative and neoplastic disorders, small molecule modulators of IRE1α, such as IRE-3 and APY-29, serve as useful tools to understand the UPR's role in pathophysiology and to develop drugs for endoplasmic reticulum stress-related diseases.

How to Use:

• In vitro: IRE-3 was used at 10-20 µM in vitro and in cellular assays.
• In vivo: n/a

Reference:

• 1. Wang L, et al. Divergent allosteric control of the IRE1α endoribonuclease using kinase inhibitors. (2012) Nat Chem Biol. 8(12):982-9.