title: Degradation of Mcl-1 by beta-TrCP mediates glycogen synthase kinase 3-induced tumor suppression and chemosensitization.
abstract: Apoptosis is critical for embryonic development, tissue homeostasis, and tumorigenesis and is determined largely by the Bcl-2 family of antiapoptotic and prosurvival regulators. Here, we report that glycogen synthase kinase 3 (GSK-3) was required for Mcl-1 degradation, and we identified a novel mechanism for proteasome-mediated Mcl-1 turnover in which GSK-3beta associates with and phosphorylates Mcl-1 at one consensus motif ((155)STDG(159)SLPS(163)T; phosphorylation sites are in italics), which will lead to the association of Mcl-1 with the E3 ligase beta-TrCP, and beta-TrCP then facilitates the ubiquitination and degradation of phosphorylated Mcl-1. A variant of Mcl-1 (Mcl-1-3A), which abolishes the phosphorylations by GSK-3beta and then cannot be ubiquitinated by beta-TrCP, is much more stable than wild-type Mcl-1 and able to block the proapoptotic function of GSK-3beta and enhance chemoresistance. Our results indicate that the turnover of Mcl-1 by beta-TrCP is an essential mechanism for GSK-3beta-induced apoptosis and contributes to GSK-3beta-mediated tumor suppression and chemosensitization.
authors: Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA.
authors: Qingqing
authors: Q
authors: Ding
authors: Xianghuo
authors: X
authors: He
authors: Jung-Mao
authors: JM
authors: Hsu
authors: Weiya
authors: W
authors: Xia
authors: Chun-Te
authors: CT
authors: Chen
authors: Long-Yuan
authors: LY
authors: Li
authors: Dung-Fang
authors: DF
authors: Lee
authors: Jaw-Ching
authors: JC
authors: Liu
authors: Qing
authors: Q
authors: Zhong
authors: Xiaodong
authors: X
authors: Wang
authors: Mien-Chie
authors: MC
authors: Hung
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008819:Mice, Nude; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D044844:beta-Transducin Repeat-Containing Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; C579094:Mcl1 protein, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D044844:beta-Transducin Repeat-Containing Proteins; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3; D046988:Proteasome Endopeptidase Complex