title: p21(Waf1/Cip1) is an assembly factor required for platelet-derived growth factor-induced vascular smooth muscle cell proliferation.
abstract: The cyclin-dependent kinase inhibitors interact with cyclin-cdk complexes to arrest mitogen-stimulated transit through the cell cycle, but these proteins have recently been shown to have positive regulatory effects on cyclin-cdk complex activity as well. Most of the previous work in this area has focussed on the finding that overexpressed p21(Waf1/Cip1) causes growth arrest. However, mice lacking p21(Waf1/Cip1) showed normal development with no aberrancy in their cell cycles, and antisense p21(Waf1/Cip1) has only been shown to prevent cell cycle arrest, leading to the conclusion that the cyclin kinase inhibitors may not be required for cell cycle progression. We found that transfection of several lines of vascular smooth muscle cells with antisense oligodeoxynucleotide specific to p21(Waf1/Cip1) correlates with decreased cyclin D1/cdk 4, but not cyclin E/cdk 2, association, yet, unexpectedly, results in dose-dependent inhibition of platelet-derived growth factor-BB-stimulated DNA synthesis and cell proliferation. Our finding that p21(Waf1/Cip1) exhibits permissive effects on growth factor-induced vascular smooth muscle cell cycle progression, such that its presence is required for growth factor-induced proliferation, is the first such report and opens up a fertile area of research relevant to diseases involving vascular cell proliferation.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, University of California, Davis, California 95616, USA. rhweiss@ucdavis.edu
authors.forename: R H
authors.initials: RH
authors.lastname: Weiss
authors.forename: A
authors.initials: A
authors.lastname: Joo
authors.forename: C
authors.initials: C
authors.lastname: Randour
mesh_terms: D000818:Animals; D001011:Aorta; D000077214:Becaplermin; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D019938:Cyclin D1 / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D014162:Transfection
chemical_list: C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; C493958:Cdkn1a protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D020319:Oligodeoxyribonucleotides, Antisense; D010982:Platelet-Derived Growth Factor; D011518:Proto-Oncogene Proteins; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D019938:Cyclin D1; D000077214:Becaplermin; C495900:CDK4 protein, human; C495902:Cdk4 protein, mouse; C495903:Cdk4 protein, rat; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases