Levels and interactions of p27, cyclin D3, and CDK4 during the formation and maintenance of the corpus luteum in mice.
The cyclin-dependent kinase (CDK) inhibitor p27, the regulator of the cell cycle, is required for proper functioning of luteinizing/luteinized cells in vivo. Since different members of the CDK family may be targeted by p27 during luteinization-associated cell cycle exit, this in vivo study further analyzed the organization of the network of cell cycle regulators that may underlie both the establishment and maintenance of the luteal phenotype. Most importantly, it shows that the luteinization process is associated with down-regulation of CDK2 and cyclin D1, and up-regulation of p27 and cyclin D3. Both p27 and cyclin D3 proteins not only accumulated during initial phases of luteinization, but they remained elevated until termination of the luteal function. Along with its accumulation, p27 lost physical contact with CDK2 and instead became associated with CDK4. In fully luteinized cells, all cyclin D3 was incorporated into complexes with p27, some complexes being p27/cyclin D3/CDK4 trimers. Despite the significant amounts of CDK4 and CDK6, only nonphosphorylated forms of retinoblastoma protein were detectable in fully luteinized cells. Together, our data indicate that while inhibition of proliferation is underlaid by the progressive loss of positive regulators of the cell cycle, including cyclins and CDK2, maintenance of the luteal phenotype is driven by up-regulated levels of p27 and cyclin D3, at least partially owing to formation of p27/cyclin D3/CDK4 trimers.
Hampl
A
A
Laboratory of Molecular Embryology, Mendel University Brno, 613 00 Brno, Czech Republic.
Pacherník
J
J
Dvorák
P
P
D000818:Animals; D042846:CDC2-CDC28 Kinases; D018797:Cell Cycle Proteins; D002455:Cell Division; D003338:Corpus Luteum / Q000378:metabolism*; D019938:Cyclin D1 / Q000378:metabolism; D056743:Cyclin D3; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism*; D005260:Female; D008183:Luteal Phase / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D016160:Retinoblastoma Protein / Q000378:metabolism; D025521:Tumor Suppressor Proteins
C534697:Ccnd3 protein, mouse; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D056743:Cyclin D3; D016213:Cyclins; D008869:Microtubule-Associated Proteins; D011518:Proto-Oncogene Proteins; D016160:Retinoblastoma Protein; D025521:Tumor Suppressor Proteins; D019938:Cyclin D1; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495893:Cdk2 protein, mouse; C495902:Cdk4 protein, mouse; C495912:Cdk6 protein, mouse; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D018844:Cyclin-Dependent Kinases