The D-type cyclins (D1, D2 and D3) are critical governors of the cell-cycle clock apparatus during the G1 phase of the mammalian cell cycle. These three D-type cyclins are expressed in overlapping, apparently redundant fashion in the proliferating tissues. A human D-type cyclin gene (CCND1/cyclin D1/PRAD1) was isolated by virtue of its ability to complement a triple G1 cyclin (Cln) deficiency of Saccharomyces cerevisiae and was also identified as a candidate Bcl1 oncogene. Xiong et al. (1992) reported the molecular cloning of two additional human D-type cyclin genes, CCND2 (cyclin D2) and CCND3 (cyclin D3). All three human D-type cyclin genes encode small (33-34 kDa) proteins that share an average of 57% identity over the entire coding region and 78% in the cyclin box. The product of the retinoblastoma susceptibility gene acts as a tumor suppressor and loss of its function is involved in the development of various types of cancer. DNA tumor viruses are suggested to disturb the normal regulation of the cell cycle by inactivating the RB gene product. Muller et al. (1994) demonstrated that the cell cycle-dependent expression of cyclin D1 is dependent on the presence of a functional RB protein. RB-deficient tumor cell lines, as well as cells expressing viral oncoproteins, had low or barely detectable levels of cyclin D1.
NCBI Summary:
The protein encoded by this gene 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. Different cyclins exhibit distinct expression and degradation patterns which contribute to the temporal coordination of each mitotic event. This cyclin 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.
Robker et al. (1998) showed that cyclin D2 mRNA was specifically localized to granulosa cells of growing follicles, while cyclin D1 and cyclin D3 were restricted to theca cells.
Follicle stages
Primordial, Secondary, Antral, Preovulatory
Comment
Arraztoa JA, et al 2005 reported the identification of genes expressed in primate primordial oocytes.