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Article Dans Une Revue Oncogene Année : 2001

Human cyclin C protein is stabilized by its associated kinase cdk8, independently of its catalytic activity

Résumé

Cyclin C belongs to the cyclin family of proteins that control cell cycle transitions through activation of specific catalytic subunits, the cyclin-dependent kinases (CDKs). However, there is as yet no evidence for any role of cyclin C and its partner, cdk8, in cell cycle regulation. Rather, the cyclin C-cdk8 complex was found associated with the RNA polymerase II transcription machinery. The periodic degradation of bona fide cyclins is crucial for cell-cycle progression and depends on the catalytic activity of the associated CDK. Here we show that endogenous cyclin C protein is quite stable with a half-life of 4 h. In contrast, exogenously expressed cyclin C is very unstable (half-life 15 min) and degraded by the ubiquitin-proteasome pathway. Co-expression with its associated cdk, however, strongly stabilizes cyclin C and results in a protein half-life near that of endogenous cyclin C. In stark contrast to data reported for other members of the cyclin family, both catalytically active and inactive cdk8 induce cyclin C stabilization. Moreover, this stabilization is accompanied in both cases by phosphorylation of the cyclin, which is not detectable when unstable. Our results indicate that cyclin C has apparently diverged from other cyclins in the regulation of its stability by its CDK partner.

Dates et versions

hal-02197302 , version 1 (30-07-2019)

Identifiants

Citer

C. Barette, I. Jariel-Encontre, Marc Piechaczyk, J. Piette. Human cyclin C protein is stabilized by its associated kinase cdk8, independently of its catalytic activity. Oncogene, 2001, 20 (5), pp.551--62. ⟨10.1038/sj.onc.1204129⟩. ⟨hal-02197302⟩
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