Combinatorial roles of protein kinase A, Ets2, and 3',5'-cyclic-adenosine monophosphate response element-binding protein-binding protein/p300 in the transcriptional control of interferon-tau expression in a trophoblast cell line.
In ruminants, conceptus interferon-tau (IFNT) production is necessary for maintenance of pregnancy. We examined the role of protein kinase A (PKA) in regulating IFNT expression through the activation of Ets2 in JAr choriocarcinoma cells. Although overexpression of the catalytic subunit of PKA or the addition of 8-bromo-cAMP had little ability to up-regulate boIFNT1 reporter constructs on their own, coexpression with Ets2 led to a large increase in gene expression. Progressive truncation of reporter constructs indicated that the site of PKA/Ets2 responsiveness lay in a region of the promoter between -126 and -67, which lacks a cAMP response element but contains the functional Ets2-binding site and an activator protein 1 (AP1) site. Specific mutation of the former reduced the PKA/Ets2 effects by more than 98%, whereas mutation of an AP1-binding site adjacent to the Ets2 site or pharmacological inhibition of MAPK kinase 2 led to a doubling of the combined Ets2/PKA effects, suggesting there is antagonism between the Ras/MAPK pathway and the PKA signal transduction pathway. Although Ets2 is not a substrate for PKA, lowering the effective concentrations of the coactivators, cAMP response element-binding protein-binding protein (CBP)/p300, known PKA targets, reduced the ability of PKA to synergize with Ets2, suggesting that PKA effects on IFNT regulation might be mediated through CBP/p300 coactivation, particularly as CBP and Ets2 occupy the proximal promoter region of IFNT in bovine trophoblast CT-1 cells. The up-regulation of IFNT in the elongating bovine conceptus is likely due to the combinatorial effects of PKA, Ets2, and CBP/p300 and triggered via growth factors released from maternal endometrium.
Das
Padmalaya
P
Christopher S. Bond Life Sciences Center, University of Missouri-Columbia, 1201 East Rollins Street, Columbia, MO 65211-7310, USA.
Ezashi
Toshihiko
T
Gupta
Rangan
R
Roberts
R Michael
RM
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002417:Cattle; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D007370:Interferon Type I / Q000235:genetics*; D009154:Mutation; D010766:Phosphorylation; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D050787:Proto-Oncogene Protein c-ets-2 / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D050880:p300-CBP Transcription Factors / Q000235:genetics / Q000378:metabolism*
C494069:ETS2 protein, human; D007370:Interferon Type I; D011257:Pregnancy Proteins; D050787:Proto-Oncogene Protein c-ets-2; D034741:RNA, Small Interfering; C020947:interferon tau; D050880:p300-CBP Transcription Factors; D017868:Cyclic AMP-Dependent Protein Kinases