title: Regulation of stability of cyclin-dependent kinase CDK11p110 and a caspase-processed form, CDK11p46, by Hsp90.
abstract: CDK11p110 (cyclin-dependent kinase 11p110, formerly known as PITSLRE) is a member of the CDK superfamily. It associates with cyclin L and is involved in the regulation of transcription and in premRNA splicing. During staurosporine-, Fas- and tumour necrosis factor a-induced apoptosis, CDK11p110, is cleaved by caspases to generate smaller 46-50 kDa proteins containing the catalytic kinase domain. Ectopic expression of the caspase-processed form CDK11p46 induces apoptosis. The mechanisms that regulate activation and stability of CDK11 isoforms are still unclear. In the present study, we demonstrate that in human melanoma cells CDK11p110 and CDK11p46 interact with Hsp90 (heat-shock protein 90) and its co-chaperone cdc37. Furthermore, we show that the treatment of cells with the Hsp90-specific inhibitor geldanamycin leads to ubiquitination and enhanced degradation of both CDK11p110 and CDK11p46 through a proteasome-dependent pathway. We also determined that geldanamycin-triggered degradation of CDK11p46 slows down the progression of apoptosis. These results indicate that Hsp90 and cdc37 stabilize CDK11 kinase, and suggest that this stabilization is crucial for its pro-apoptotic function.
authors.affiliation: Department of Pathology, Arizona Cancer Center, College of Medicine, University of Arizona, Tucson, AZ 85724, USA.
authors.forename: Monika
authors.initials: M
authors.lastname: Mikolajczyk
authors.forename: Mark A
authors.initials: MA
authors.lastname: Nelson
mesh_terms: D017209:Apoptosis; D020169:Caspases / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D018833:Chaperonins; D018844:Cyclin-Dependent Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006207:Half-Life; D006801:Humans; D047468:Immunoprecipitation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational
chemical_list: C498362:CDC37 protein, human; D018797:Cell Cycle Proteins; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; C447612:CDK11a protein, human; D018844:Cyclin-Dependent Kinases; D020169:Caspases; D046988:Proteasome Endopeptidase Complex; D018833:Chaperonins