title: P21(Cip1) induced by Raf is associated with increased Cdk4 activity in hematopoietic cells.
abstract: To investigate the functions of the different Raf genes in hematopoietic cell proliferation, the capacities of beta-estradiol-regulated Delta Raf:ER genes to induce cell cycle regulatory gene expression and cell cycle progression in FDC-P1 cells were examined. Raf activation increased the expression of Cdk2, Cdk4, cyclin A, cyclin D, cyclin E, p21(Cip1) and c-Myc and decreased the expression of p27(Kip1) which are associated with G(1) progression. However only the cell clones with moderate Raf activation, i.e. FD/Delta Raf-1:ER and FD/Delta A-Raf:ER, successfully underwent cell proliferation. The cell clones with the highest Delta Raf activity, FD/Delta B-Raf:ER, underwent apoptosis before cell proliferation. p21(Cip1) induced by Raf activation specifically bound with Cdk4/cyclin D complexes but not Cdk2/cyclin E complexes and this binding was associated with the increased Cdk4 activity. However, no binding of p27(Kip1) with either Cdk2/cyclin E or Cdk4/cyclin D was observed. Thus Raf mediated growth was associated with elevated p21(Cip1) expression, which may specifically bind with and activate Cdk4/cyclin D complexes and with decreased p27(Kip1) expression.
authors.affiliation: Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, North Carolina, NC 27858, USA.
authors.forename: F
authors.initials: F
authors.lastname: Chang
authors.forename: J A
authors.initials: JA
authors.lastname: McCubrey
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division; D002460:Cell Line; D002999:Clone Cells; D056741:Cyclin D; D051358:Cyclin-Dependent Kinase 4; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism*; D004789:Enzyme Activation; D004958:Estradiol / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D048369:MAP Kinase Kinase 1; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics / Q000502:physiology*; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D025521:Tumor Suppressor Proteins
chemical_list: C493957:Cdkn1a protein, mouse; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D056741:Cyclin D; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D011518:Proto-Oncogene Proteins; D011960:Receptors, Estrogen; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004958:Estradiol; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; C495902:Cdk4 protein, mouse; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases; D048369:MAP Kinase Kinase 1; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases