Loss of soluble N-ethylmaleimide-sensitive factor attachment protein α (αSNAP) induces epithelial cell apoptosis via down-regulation of Bcl-2 expression and disruption of the Golgi

J Biol Chem. 2012 Feb 17;287(8):5928-41. doi: 10.1074/jbc.M111.278358. Epub 2011 Dec 22.

Abstract

Intracellular trafficking represents a key mechanism that regulates cell fate by participating in either prodeath or prosurvival signaling. Soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein α (αSNAP) is a well known component of vesicle trafficking machinery that mediates intermembrane fusion. αSNAP increases cell resistance to cytotoxic stimuli, although mechanisms of its prosurvival function are poorly understood. In this study, we found that either siRNA-mediated knockdown of αSNAP or expression of its dominant negative mutant induced epithelial cell apoptosis. Apoptosis was not caused by activation of the major prodeath regulators Bax and p53 and was independent of a key αSNAP binding partner, NSF. Instead, death of αSNAP-depleted cells was accompanied by down-regulation of the antiapoptotic Bcl-2 protein; it was mimicked by inhibition and attenuated by overexpression of Bcl-2. Knockdown of αSNAP resulted in impairment of Golgi to endoplasmic reticulum (ER) trafficking and fragmentation of the Golgi. Moreover, pharmacological disruption of ER-Golgi transport by brefeldin A and eeyarestatin 1 or siRNA-mediated depletion of an ER/Golgi-associated p97 ATPase recapitulated the effects of αSNAP inhibition by decreasing Bcl-2 level and triggering apoptosis. These results reveal a novel role for αSNAP in promoting epithelial cell survival by unique mechanisms involving regulation of Bcl-2 expression and Golgi biogenesis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenosine Triphosphatases / antagonists & inhibitors
  • Apoptosis / drug effects
  • Apoptosis / genetics*
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Down-Regulation / drug effects
  • Down-Regulation / genetics*
  • Endoplasmic Reticulum / drug effects
  • Endoplasmic Reticulum / metabolism
  • Endoplasmic Reticulum Stress / drug effects
  • Endoplasmic Reticulum Stress / genetics
  • Enzyme Inhibitors / pharmacology
  • Epithelial Cells / cytology*
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism
  • Golgi Apparatus / drug effects
  • Golgi Apparatus / metabolism*
  • HCT116 Cells
  • Humans
  • Nuclear Proteins / antagonists & inhibitors
  • Protein Transport / drug effects
  • Protein Transport / genetics
  • Proto-Oncogene Proteins c-bcl-2 / genetics*
  • RNA, Small Interfering / genetics
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / deficiency*
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / genetics*
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / metabolism

Substances

  • Enzyme Inhibitors
  • Nuclear Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
  • Adenosine Triphosphatases
  • p97 ATPase