Int. J. Dev. Biol. 52: 299 - 305 (2008)

https://doi.org/10.1387/ijdb.072336mc

Vol 52, Issue 2-3

Special Issue: Developmental Biology in Poland

CDK4 activity in mouse embryos expressing a single D-type cyclin

Published: 14 February 2008

Maria A. Ciemerych^1,2,*, Qunyan Yu³, Katarzyna Szczepanska¹ and Piotr Sicinski¹

¹Department of Embryology and ²Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, Warsaw, Poland, ³Dana-Farber Cancer Institute, Harvard Medical School, Boston, USA

Abstract

D-type cyclins (D1, D2, and D3) are components of the cell cycle machinery. Their association with cyclin-dependent kinase 4 (CDK4) and CDK6 causes activation of these protein kinases and leads to phosphorylation and inactivation of the retinoblastoma protein, pRb. Using embryos expressing single D-type cyclin ('cyclin D1-only', 'cyclin D2-only' and 'cyclin D3-only'), we tested whether each of D-type cyclin plays the same role in CDK activation and phosphorylation of pRb during mouse embryonic development. We found that the level of CDK4 activity was similar in wild-type embryos and those expressing only cyclin D3 or cyclin D2. However, we did not detect CDK4 activity in embryos expressing only cyclin D1, despite the fact that this cyclin was able to form complexes with CDK4 and p27^kip1 in wild-type as well as in mutant embryos. Analysis of the expression pattern of mRNA encoding cyclin D1 revealed that the expression of this RNA is regulated temporally during embryogenesis. These data and results from other laboratories indicate that cyclin D1-dependent CDK4 activity is dispensable for normal development of the mouse embryo.

Keywords

mouse, embryogenesis, CDK4, cyclin D, p27kip1, retinoblastoma protein