X-linked inhibitor of apoptosis protein functions as a cofactor in transforming growth factor-beta signaling

J Biol Chem. 2001 Jul 13;276(28):26542-9. doi: 10.1074/jbc.M100331200. Epub 2001 May 16.

Abstract

X-linked inhibitor of apoptosis protein (XIAP) is a potent suppressor of apoptotic cell death, which functions by directly inhibiting caspases, the principal effectors of apoptosis. Here we report that XIAP can also function as a cofactor in the regulation of gene expression by transforming growth factor-beta (TGF-beta). XIAP, but not the related proteins c-IAP1 or c-IAP2, associated with several members of the type I class of the TGF-beta receptor superfamily and potentiated TGF-beta-induced signaling. Although XIAP-mediated activation of c-Jun N-terminal kinase and nuclear factor kappa B was found to require the TGF-beta signaling intermediate Smad4, the ability of XIAP to suppress apoptosis was found to be Smad4-independent. These data implicate a role for XIAP in TGF-beta-mediated signaling that is distinct from its anti-apoptotic functions.

MeSH terms

  • Apoptosis / physiology
  • Cell Line
  • Gene Expression Regulation / physiology
  • Humans
  • Proteins / physiology*
  • Signal Transduction
  • Transforming Growth Factor beta / physiology*
  • X-Linked Inhibitor of Apoptosis Protein

Substances

  • Proteins
  • Transforming Growth Factor beta
  • X-Linked Inhibitor of Apoptosis Protein
  • XIAP protein, human