Submitted to: Molecular Reproduction and Development
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/22/2002
Publication Date: 5/20/2003
Citation: XU,N., TAKAHASHI,Y., MATSUDA,F., SAKAI,S., CHRISTENSON,R.K., IMAKAWA,K., COACTIVATOR CBP IN THE REGULATION OF CONCEPTUS IFNTAU GENE TRANSCRIPTION, Molecular Reproduction and Development, 65(1):23-29, 2003. Interpretive Summary: Biochemical communications between the developing conceptus and the mammalian uterus are important for successful implantation. A large majority of reproductive failure in sheep occur as a result of an impaired signal from the developing conceptus to the maternal system. In sheep, the gene controlling the conceptus signaling product (ovine interferon-tau, oIFNtau) is known. The objective of this study was to determine if coactivator cAMP-response element binding protein (CBP) interacted with several nuclear transcription factors that bind to specific enhancer and promoter sites of the oIFNtau gene during transcription. Results provide evidence that the CBP coactivator and one of several nuclear proteins (c-jun) examined bind with specific IFNtau gene enhancer regions and stimulate increased IFNtau gene transcription. Therefore, enhancement of the oIFNtau gene transcription may improve implantation and conceptus/embryo survival in sheep.
Technical Abstract: Studies of ovine interferon-tau (oIFNtau) gene regulation, an anti-luteolytic factor produced by conceptuses of the ruminant ungulates, have been carried out, but a definitive mechanism for its spatial-temporal transcription has not been elucidated. Recently, specific binding regions for transcription factors AP-l and Ets-2 on the oIFNtau gene were identified; however, a molecular mechanism by which these factors regulate oIFNtau gene transcription has not been characterized. In the present study, we investigated the potential relationship between AP-l and Ets-2 and their association with a coactivator, cAMP-response element binding protein-binding protein (CBP), on oIFNtau gene transcription in a transient transfection system using human choriocarcinoma JEG3 cells. The oIFNtau gene promoter/enhancer (-654 to +1 bases, wild type)-luciferase reporter construct (pGL3-654) or its mutant at the AP-l or Ets-2 site was cotransfected with CBP (pRc/RSV-CBP) construct along with c-jun, c-fos and/or Ets-2 expression plasmid. CBP enhanced transcription of the wild type oIFNtau-reporter construct; however, this coactivator had no effect on the oIFNtau-reporter construct with mutated AP-l or Ets-2 sites. Cotransfection of CBP with c-jun and/or Ets-2, but not with c-fos, further increased oIFNtau gene transactivation although amounts of c-jun and c-fos expression, resulting from expression vectors, were similar. In addition, CBP inhibitor adenovirus l2S E1A (E1A), but not the mutant of E1A without CBP binding domain (delta2-36), suppressed oIFNtau gene transcription. These observations suggest that c-jun and Ets-2 are the most probable binding partners for CBP in the potentiation of oIFNtau gene transcription.