title: 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.
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.
authors.affiliation: Department of Medicine, University of Rochester, Rochester, New York 14642, USA.
authors.forename: Nayden G
authors.initials: NG
authors.lastname: Naydenov
authors.forename: Gianni
authors.initials: G
authors.lastname: Harris
authors.forename: Bryan
authors.initials: B
authors.lastname: Brown
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Schaefer
authors.forename: Swadesh K
authors.initials: SK
authors.lastname: Das
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fisher
authors.forename: Andrei I
authors.initials: AI
authors.lastname: Ivanov
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism*; D045325:HCT116 Cells; D006801:Humans; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / Q000172:deficiency* / Q000235:genetics* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D009687:Nuclear Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D000251:Adenosine Triphosphatases; C404942:p97 ATPase