Mitotic control of RUNX2 phosphorylation by both CDK1/cyclin B kinase and PP1/PP2A phosphatase in osteoblastic cells
Authors
Rajgopal, ArunYoung, Daniel W.
Mujeeb, Khwaja A.
Stein, Janet L.
Lian, Jane B.
Van Wijnen, Andre J.
Stein, Gary S.
UMass Chan Affiliations
Department of Cell Biology and Cancer CenterGraduate School of Biomedical Sciences
Graduate School of Biomedical Sciences
Document Type
Journal ArticlePublication Date
2006-12-16Keywords
Blotting, Western; CDC2 Protein Kinase; Cell Cycle; Cell Line, Tumor; Core Binding Factor Alpha 1 Subunit; Cyclin B; Electrophoresis, Polyacrylamide Gel; Enzyme Activation; Humans; Immunoprecipitation; Mitosis; Mutagenesis, Site-Directed; Okadaic Acid; Osteoblasts; Osteosarcoma; Phosphoprotein Phosphatases; Phosphorylation; Protein Binding; Purines; TransfectionLife Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
Skeletal development and osteoblast maturation require the phenotype promoting activity of the transcription factor RUNX2, which controls both cell growth and differentiation in osteoblasts. We have recently shown that in actively proliferating cells RUNX2 regulates the expression of specific target genes as cells enter and exit mitosis. In this study, we addressed whether post-translational modifications of RUNX2 control its activity during mitotic exit. Western blot analysis of proteins from osteoblastic Saos-2 cells released from mitotic inhibition into early G(1) show a phosphatase-sensitive shift in the mobility of RUNX2 in SDS gels. The slowly migrating hyper-phosphorylated form of RUNX2 is immunoreactive with a CDK related phospho-antibody (MPM2) only in mitotic cells and is converted into a faster migrating hypo-phosphorylated RUNX2 when cells complete mitosis. This conversion is inhibited by okadaic acid, an inhibitor of protein phosphatases 1 and 2 (PP1 and PP2A), but not by deltamethrin which blocks PP2B phosphatase. Mitotic phosphorylation of RUNX2 is sensitive to the CDK inhibitors roscovitine and olomoucine. Furthermore, RUNX2 can directly interact with CDK1 and is phosphorylated in vitro by the CDK1/cyclin B kinase complex. Hence, RUNX2 is hyper-phosphorylated by CDK1/cyclin B during mitosis, and dynamically converted into a hypo-phosphorylated form by PP1/PP2A-dependent dephosphorylation after mitosis to support the post-mitotic regulation of RUNX2 target genes.Source
J Cell Biochem. 2007 Apr 15;100(6):1509-17. Link to article on publisher's siteDOI
10.1002/jcb.21137Permanent Link to this Item
http://hdl.handle.net/20.500.14038/32441PubMed ID
17171635Related Resources
Link to article in PubMedae974a485f413a2113503eed53cd6c53
10.1002/jcb.21137