title: Antiapoptotic protein Lifeguard is required for survival and maintenance of Purkinje and granular cells.
abstract: Lifeguard (LFG) is an inhibitor of Fas-mediated cell death and is highly expressed in the cerebellum. We investigated the biological role of LFG in the cerebellum in vivo, using mice with reduced LFG expression generated by shRNA lentiviral transgenesis (shLFG mice) as well as LFG null mice. We found that LFG plays a role in cerebellar development by affecting cerebellar size, internal granular layer (IGL) thickness, and Purkinje cell (PC) development. All these features are more severe in early developmental stages and show substantial recovery overtime, providing a remarkable example of cerebellar plasticity. In adult mice, LFG plays a role in PC maintenance shown by reduced cellular density and abnormal morphology with increased active caspase 8 and caspase 3 immunostaining in shLFG and knockout (KO) PCs. We studied the mechanism of action of LFG as an inhibitor of the Fas pathway and provided evidence of the neuroprotective role of LFG in cerebellar granule neurons (CGNs) and PCs in an organotypic cerebellar culture system. Biochemical analysis of the Fas pathway revealed that LFG inhibits Fas-mediated cell death by interfering with caspase 8 activation. This result is supported by the increased number of active caspase 8-positive PCs in adult mice lacking LFG. These data demonstrate that LFG is required for proper development and survival of granular and Purkinje cells and suggest LFG may play a role in cerebellar disorders.
authors.affiliation: Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Hurtado de Mendoza
authors.forename: Carlos G
authors.initials: CG
authors.lastname: Perez-Garcia
authors.forename: Todd T
authors.initials: TT
authors.lastname: Kroll
authors.forename: Nien H
authors.initials: NH
authors.lastname: Hoong
authors.forename: Dennis D M
authors.initials: DD
authors.lastname: O'Leary
authors.forename: Inder M
authors.initials: IM
authors.lastname: Verma
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002531:Cerebellum / Q000002:abnormalities / Q000166:cytology* / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D011689:Purkinje Cells / Q000166:cytology* / Q000502:physiology*; D034741:RNA, Small Interfering / Q000235:genetics; D019014:fas Receptor / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C400427:FAIM2 protein, human; C491901:FAS protein, human; C491899:Fas protein, mouse; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D034741:RNA, Small Interfering; D019014:fas Receptor; C523971:lifeguard protein, mouse; C505409:Casp3 protein, mouse; C505526:Casp8 protein, mouse; D053148:Caspase 3; D053181:Caspase 8