title: CDK-independent activation of estrogen receptor by cyclin D1.
abstract: Both cyclin D1 and estrogens have an essential role in regulating proliferation of breast epithelial cells. We show here a novel role for cyclin D1 in growth regulation of estrogen-responsive tissues by potentiating transcription of estrogen receptor-regulated genes. Cyclin D1 mediates this activation independent of complex formation to a CDK partner. Cyclin D1 activates estrogen receptor-mediated transcription in the absence of estrogen and enhances transcription in its presence. The activation of estrogen receptor by cyclin D1 is not inhibited by anti-estrogens. A direct physical binding of cyclin D1 to the hormone binding domain of the estrogen receptor results in an increased binding of the receptor to estrogen response element sequences, and upregulates estrogen receptor-mediated transcription. These results highlight a novel role for cyclin D1 as a CDK-independent activator of the estrogen receptor.
authors.affiliation: Department of Tumor Biology, Netherlands Cancer Institute (Antoni van Leeuwenhoekhuis), Amsterdam.
authors.forename: R M
authors.initials: RM
authors.lastname: Zwijsen
authors.forename: E
authors.initials: E
authors.lastname: Wientjens
authors.forename: R
authors.initials: R
authors.lastname: Klompmaker
authors.forename: J
authors.initials: J
authors.lastname: van der Sman
authors.forename: R
authors.initials: R
authors.lastname: Bernards
authors.forename: R J
authors.initials: RJ
authors.lastname: Michalides
mesh_terms: D001483:Base Sequence; D019938:Cyclin D1; D018844:Cyclin-Dependent Kinases / Q000502:physiology*; D016213:Cyclins / Q000378:metabolism / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008024:Ligands; D015513:Oncogene Proteins / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
chemical_list: D016213:Cyclins; D008024:Ligands; D015513:Oncogene Proteins; D011960:Receptors, Estrogen; D019938:Cyclin D1; D004958:Estradiol; D018844:Cyclin-Dependent Kinases