Cyclin D1

Cyclin D1 is a protein that in humans is encoded by the CCND1 gene. It belongs to the highly conserved cyclin family, whose members are characterized by a dramatic periodicity in protein abundance throughout the cell cycle. Cyclins function as regulators of CDK kinases.

Function

Cyclin D1 forms a complex with and functions as a regulatory subunit of CDK4 or CDK6, whose activity is required for cell cycle G1/S transition. This protein has been shown to interact with tumor suppressor protein Rb and the expression of this gene is regulated positively by Rb. Mutations, amplification and overexpression of this gene, which alters cell cycle progression, are observed frequently in a variety of tumors and may contribute to tumorigenesis.

Clinical significance

Abnormal overexpression of cyclin D1 is implicated in several types of cancer, including breast cancer, esophageal cancer, endometrial carcinoma, and mantle cell lymphoma. In mantle cell lymphoma, the overexpression of cyclin D1 is due to a t(11;14) chromosomal translocation resulting in the juxtaposition of the CCND1 gene and the immunoglobulin heavy-chain gene (IGH) enhancer.

See also

• Cyclin
• Cyclin-dependent kinase
• Cell cycle
• Tumorigenesis