title: Flotillin-2 modulates fas signaling mediated apoptosis after hyperoxia in lung epithelial cells.
abstract: Lipid rafts are subdomains of the cell membrane with distinct protein composition and high concentrations of cholesterol and glycosphingolipids. Raft proteins are thought to mediate diverse cellular processes including signal transduction. However, its cellular mechanisms remain unclear. Caveolin-1 (cav-1, marker protein of caveolae) has been thought as a switchboard between extracellular matrix (ECM) stimuli and intracellular signals. Flotillin-2/reggie-1(Flot-2) is another ubiquitously expressed raft protein which defines non-caveolar raft microdomains (planar raft). Its cellular function is largely uncharacterized. Our novel studies demonstrated that Flot-2, in conjunction with cav-1, played important functions on controlling cell death via regulating Fas pathways. Using Beas2B epithelial cells, we found that in contrast to cav-1, Flot-2 conferred cytoprotection via preventing Fas mediated death-inducing signaling complex (DISC) formation, subsequently suppressed caspase-8 mediated extrinsic apoptosis. Moreover, Flot-2 reduced the mitochondria mediated intrinsic apoptosis by regulating the Bcl-2 family and suppressing cytochrome C release from mitochondria to cytosol. Flot-2 further modulated the common apoptosis pathway and inhibited caspase-3 activation via up-regulating the members in the inhibitor of apoptosis (IAP) family. Last, Flot-2 interacted with cav-1 and limited its expression. Taken together, we found that Flot-2 protected cells from Fas induced apoptosis and counterbalanced the pro-apoptotic effects of cav-1. Thus, Flot-2 played crucial functions in cellular homeostasis and cell survival, suggesting a differential role of individual raft proteins.
authors.affiliation: Division of Pulmonary and Critical Care, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America ; Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, China.
authors.forename: Shuquan
authors.initials: S
authors.lastname: Wei
authors.forename: Hyung-Geun
authors.initials: HG
authors.lastname: Moon
authors.forename: Yijie
authors.initials: Y
authors.lastname: Zheng
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Liang
authors.forename: Chang Hyeok
authors.initials: CH
authors.lastname: An
authors.forename: Yang
authors.initials: Y
authors.lastname: Jin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D016923:Cell Death / Q000502:physiology; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D018496:Hyperoxia / Q000378:metabolism*; D008168:Lung / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D019014:fas Receptor / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D019014:fas Receptor; C106354:flotillins; D053148:Caspase 3; D053181:Caspase 8