title: Cdc25B functions as a novel coactivator for the steroid receptors.
abstract: We have previously demonstrated that overexpression of Cdc25B in transgenic mice resulted in mammary gland hyperplasia and increased steroid hormone responsiveness. To address how Cdc25B enhances the hormone responsiveness in mammary glands, we showed that Cdc25B stimulates steroid receptor-dependent transcription in transient transfection assays and in a cell-free assay with chromatin templates. Surprisingly, the effect of Cdc25B on steroid receptors is independent of its protein phosphatase activity in vitro. The direct interactions of Cdc25B with steroid receptors, on the other hand, were evidenced in in vivo and in vitro assays, suggesting the potential direct contribution of Cdc25B on the steroid receptor-mediated transcription. In addition, p300/CBP-associated factor and CREB binding protein were shown to interact and synergize with Cdc25B and further enhance its coactivation activity. Thus, we have uncovered a novel function of Cdc25B that serves as a steroid receptor coactivator in addition to its role as a regulator for cell cycle progression. This dual function might likely contribute to its oncogenic action in breast cancer.
authors.affiliation: Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Ma
authors.forename: Z
authors.initials: Z
authors.lastname: Liu
authors.forename: E S
authors.initials: ES
authors.lastname: Ngan
authors.forename: S Y
authors.initials: SY
authors.lastname: Tsai
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D000818:Animals; D001940:Breast / Q000378:metabolism*; D050882:CREB-Binding Protein; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism* / Q000494:pharmacology; D002460:Cell Line; D002474:Cell-Free System / Q000378:metabolism; D019938:Cyclin D1 / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D051548:Histone Acetyltransferases; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D051381:Rats; D011944:Receptors, Androgen / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D011987:Receptors, Steroid / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D020687:cdc25 Phosphatases / Q000378:metabolism* / Q000494:pharmacology; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
chemical_list: D000123:Acetyltransferases; D050882:CREB-Binding Protein; D018797:Cell Cycle Proteins; D019938:Cyclin D1; D051548:Histone Acetyltransferases; D009687:Nuclear Proteins; D011944:Receptors, Androgen; D011960:Receptors, Estrogen; D011965:Receptors, Glucocorticoid; D011980:Receptors, Progesterone; D011987:Receptors, Steroid; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D020687:cdc25 Phosphatases; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C097314:progesterone receptor B; C494363:CREBBP protein, human; C494365:Crebbp protein, rat; C517008:CDC25B protein, human