title: Transforming growth factor-β1 induces cell cycle arrest by activating atypical cyclin-dependent kinase 5 through up-regulation of Smad3-dependent p35 expression in human MCF10A mammary epithelial cells.
abstract: Cyclin-dependent kinases (Cdks) play important roles in control of cell division. Cdk5 is an atypical member of Cdk family with non-cyclin-like regulatory subunit, p35, but its role in cell cycle progression is still unclear. In the present study, we investigated the role of Cdk5/p35 on transforming growth factor-β1 (TGF-β1)-induced cell cycle arrest. In human MCF10A mammary epithelial cells, TGF-β1 induced cell cycle arrest at G1 phase and increased p27KIP1 expression. Interestingly, pretreatment with roscovitine, an inhibitor of Cdk5, or transfection with small interfering (si) RNAs specific to Cdk5 and p35 significantly attenuated the TGF-β1-induced p27KIP1 expression and cell cycle arrest. TGF-β1 increased Cdk5 activity via up-regulation of p35 gene at transcriptional level, and these effects were abolished by transfection with Smad3 siRNA or infection of adenovirus carrying Smad3 mutant at the C-tail (3SA). Chromatin immunoprecipitation assay further revealed that wild type Smad3, but not mutant Smad3 (3SA), binds to the region of the p35 promoter region (-1000--755) in a TGF-β1-dependent manner. These results for the first time demonstrate a role of Cdk5/p35 in the regulation of cell cycle progression modulated by TGF-β1.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Seong Ji
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Sun Woo
authors.initials: SW
authors.lastname: Yang
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, South Korea. Electronic address: bckim@kangwon.ac.kr.
authors.forename: Byung-Chul
authors.initials: BC
authors.lastname: Kim
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D059447:Cell Cycle Checkpoints / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D051360:Cyclin-Dependent Kinase 5 / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D006801:Humans; D042361:Mammary Glands, Human / Q000166:cytology / Q000378:metabolism*; D051900:Smad3 Protein / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D000099222:betaIG-H3 Protein
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D051360:Cyclin-Dependent Kinase 5; D016326:Extracellular Matrix Proteins; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; D000099222:betaIG-H3 Protein; C500695:CDCA5 protein, human; C497790:SMAD3 protein, human; C495905:CDK5 protein, human
keywords: Cdk5; Cell cycle arrest; Smad3; TGF-β1; p35