title: HSP90 protects apoptotic cleavage of vimentin in geldanamycin-induced apoptosis.
abstract: Heat shock protein (HSP) 90 is of interest as an anticancer drug target because of its importance in maintaining the conformation, stability and function of the client proteins involved in signal transduction pathways leading to proliferation, cell cycle progression, and apoptosis. Geldanamycin, a specific antagonist of HSP90, binds directly to HSP90 and promotes proteolytic degradation of client proteins of HSP90. The aim of the present study was to identify novel client proteins of HSP90 and to elucidate HSP90 function through inhibition of HSP90 binding to its client proteins, by using of geldanamycin. We investigated changes in protein profile when apoptosis was induced by exposure to geldanamycin. Differentially expressed proteins were identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), in human neuroblastoma SK-N-SH cells. The vimentin level was found to decrease dramatically by the treatment of geldanamycin. We observed subcellular co-localization of vimentin and HSP90. Physical association of vimentin with HSP90 was detected by an immunoprecipitation assay. The caspase inhibitors, Z-VAD-FMK and Ac-DEVD-CHO, completely abolished geldanamycin-induced cleavage of vimentin. Changes of HSP90 level by antisense treatment or transfection of HSP90-overexpressing vector affected geldanamycin-induced cleavage of vimentin. These results suggest that HSP90 protects vimentin by physical interaction in the geldanamycin-induced apoptotic pathway.
authors.affiliation: Department of Biochemistry and molecular Biology, ILCHUN Molecular Medicine Institute MRC, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Mei-Hua
authors.initials: MH
authors.lastname: Zhang
authors.forename: Jae-Seon
authors.initials: JS
authors.lastname: Lee
authors.forename: Hee-Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Dong-Il
authors.initials: DI
authors.lastname: Jin
authors.forename: Jong-Il
authors.initials: JI
authors.lastname: Kim
authors.forename: Kong-Joo
authors.initials: KJ
authors.lastname: Lee
authors.forename: Jeong-Sun
authors.initials: JS
authors.lastname: Seo
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D016227:Benzoquinones / Q000494:pharmacology*; D020169:Caspases / Q000502:physiology; D045744:Cell Line, Tumor; D015180:Electrophoresis, Gel, Two-Dimensional; D018841:HSP90 Heat-Shock Proteins / Q000502:physiology*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D014746:Vimentin / Q000378:metabolism*
chemical_list: D000903:Antibiotics, Antineoplastic; D016227:Benzoquinones; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D014746:Vimentin; D020169:Caspases; C001277:geldanamycin