Differential expression of AP-2gamma and AP-2alpha during human trophoblast differentiation.
Previous studies from our laboratory demonstrated that AP-2alpha induces the expression of the hPL and hCG genes in cultured trophoblast cells. In the current study, we have shown by transient transfection studies that AP-2gamma, which is the product of a separate gene from AP-2alpha, also stimulates hPL and hCGbeta promoter activities. However, AP-2gamma mRNA levels during in vitro differentiation of human cytotrophoblast cells were strikingly different than those of AP-2alpha mRNA levels, with AP-2alpha increasing and AP-2gamma markedly decreasing during the differentiation process. The amount of AP-2gamma protein binding to AP-2 elements on the hPL promoter, as determined by supershift assays, also markedly decreased during the differentiation process. These findings strongly suggest that AP-2gamma action in cytotrophoblast cells is repressed by a co-factor(s) that inhibits AP-2gamma action or is prevented by the absence of a co-factor(s) that is essential for AP-2gamma action.
Richardson
B D
BD
Department of Pediatrics, University of Cincinnati College of Medicine, OH, USA. brian.richardson.chmcc.org
Cheng
Y H
YH
Langland
R A
RA
Handwerger
S
S
D002454:Cell Differentiation; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D011247:Pregnancy; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000096:biosynthesis*; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*
D004268:DNA-Binding Proteins; C493673:TFAP2A protein, human; C493679:TFAP2C protein, human; D050656:Transcription Factor AP-2; D014157:Transcription Factors