title: Quantitative proteomic analysis of myc-induced apoptosis: a direct role for Myc induction of the mitochondrial chloride ion channel, mtCLIC/CLIC4.
abstract: Myc is a key regulatory protein in higher eukaryotes controlling important cellular functions such as proliferation, differentiation, and apoptosis. Myc is profoundly involved in the genesis of many human and animal cancers, and the abrogation of Myc-induced apoptosis is a critical event in cancer progression. Because the mechanisms that mediate Myc-induced apoptosis are largely unknown, we analyzed protein expression during Myc-induced apoptosis using an isotope-coded affinity tag quantitative proteomics approach and identified that a proapoptotic mitochondrial chloride ion channel, mtCLIC/CLIC4, is induced by Myc. Myc binds to the mtCLIC gene promoter and activates its transcription. Suppression of mtCLIC expression by RNA interference inhibited Myc-induced apoptosis in response to different stress conditions and abolished the cooperative induction of apoptosis by Myc and Bax. We also found that Myc reduces the expression of Bcl-2 and Bcl-xL and that the apoptosis-inducing stimuli up-regulate Bax expression. These results suggest that up-regulation of mtCLIC, together with a reduction in Bcl-2 and Bcl-xL, sensitizes Myc-expressing cells to the proapoptotic action of Bax.
authors.affiliation: Institute for Systems Biology, Seattle, Washington 98103-8904, USA. shiio@uthscsa.edu
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Shiio
authors.forename: Kwang S
authors.initials: KS
authors.lastname: Suh
authors.forename: Hookeun
authors.initials: H
authors.lastname: Lee
authors.forename: Stuart H
authors.initials: SH
authors.lastname: Yuspa
authors.forename: Robert N
authors.initials: RN
authors.lastname: Eisenman
authors.forename: Ruedi
authors.initials: R
authors.lastname: Aebersold
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D018118:Chloride Channels / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D024101:Mitochondrial Proteins / Q000235:genetics; D040901:Proteomics; D016271:Proto-Oncogene Proteins c-myc / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D013312:Stress, Physiological / Q000235:genetics; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000502:physiology
chemical_list: D051017:Apoptosis Regulatory Proteins; C464459:CLIC4 protein, human; D018118:Chloride Channels; D024101:Mitochondrial Proteins; D016271:Proto-Oncogene Proteins c-myc; D034741:RNA, Small Interfering; D051028:bcl-2-Associated X Protein