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Interaction between Cdc37 and Cdk4 in human cells
1Mitotix, Inc., Cambridge, Massachusetts 02139, USA.
Insights
Researchers identified Cdc37 as a novel protein interacting with Cyclin-dependent kinase 4 (Cdk4). Cdc37 facilitates Cdk4/cyclin D1 complex assembly and competes with p16 for Cdk4 binding.
Area of Science:
- Molecular Biology
- Cell Cycle Regulation
- Protein Interactions
Background:
- Cyclin-dependent kinases (Cdks) regulate cell cycle progression.
- Cdk4, in complex with D-type cyclins, is a key regulator of the G1 to S phase transition.
- Dysregulation of Cdk4 activity is implicated in various cancers.
Purpose of the Study:
- To identify novel interacting partners of Cdk4.
- To characterize the interaction between Cdk4 and its human homologue of yeast Drosophila CDC37 gene product, Cdc37.
- To elucidate the functional role of Cdc37 in Cdk4/cyclin D1 complex formation and kinase activity.
Main Methods:
- Yeast two-hybrid system for identifying protein-protein interactions.
- In vitro kinase assays to assess Cdk4/cyclin D1 activity.
- Co-immunoprecipitation to confirm protein binding.
Main Results:
- The yeast two-hybrid system identified Cdc37 as a novel Cdk4 interacting protein.
- Cdc37 specifically interacts with Cdk4 and Cdk6, but not other tested Cdks (Cdc2, Cdk2, Cdk3, Cdk5) or cyclins.
- Cdc37 facilitates the assembly of Cdk4/cyclin D1 complexes in vitro.
- Cdc37 competes with the inhibitor p16 for binding to Cdk4.
Conclusions:
- Cdc37 is a novel binding partner of Cdk4 and Cdk6.
- Cdc37 plays a role in facilitating Cdk4/cyclin D1 complex formation.
- Cdc37 may be involved in the mechanism by which p16 inhibits Cdk4 activity by interfering with complex assembly.
Abstract:
Using the yeast two-hybrid system we have identified novel potential Cdk4 interacting proteins. Here we described the interaction of Cdk4 with a human homologue of the yeast Drosophila CDC37 gene products. Cdc37 protein specifically interacts with Cdk4 and Cdk6, but not with Cdc2, Cdk2, Cdk3, Cdk5 and any of a number of cyclins tested. Cdc37 is not an inhibitor nor an activator of the Cdk4/cyclin D1 kinase, while it appears to facilitate complex assembly between Cdk4, and cyclin D1 in vitro. Cdc37 competes with p16 for binding to Cdk4, suggesting that p16 might exert part of its inhibitory function by affecting the formation of Cdk4/cyclin D1 complexes via Cdc37.