Proapoptotic BAX and BAK Modulate the Unfolded Protein Response by a Direct Interaction with IRE1
Claudio Hetz,
Paula Bernasconi,
Jill Fisher,
Ann-Hwee Lee,
Michael C. Bassik,
Bruno Antonsson,
Gabriel S. Brandt,
Neal N. Iwakoshi,
Anna Schinzel,
Laurie H. Glimcher, and
Stanley J. Korsmeyer
http://sageke.sciencemag.org/cgi/content/abstract/2006/8/or10
Abstract:
Science 312, 572-576 (2006).
Accumulation of misfolded protein in the endoplasmic reticulum (ER) triggers an adaptive stress response--termed the unfolded protein response (UPR)--mediated by the ER transmembrane protein kinase and endoribonuclease inositol-requiring enzyme-1
(IRE1
). We investigated UPR signaling events in mice in the absence of the proapoptotic BCL-2 family members BAX and BAK [double knockout (DKO)]. DKO mice responded abnormally to tunicamycin-induced ER stress in the liver, with extensive tissue damage and decreased expression of the IRE1 substrate X-box-binding protein 1 and its target genes. ER-stressed DKO cells showed deficient IRE1
signaling. BAX and BAK formed a protein complex with the cytosolic domain of IRE1
that was essential for IRE1
activation. Thus, BAX and BAK function at the ER membrane to activate IRE1
signaling and to provide a physical link between members of the core apoptotic pathway and the UPR.
[Abstract/Full Text]