Abstract
We screened a term placental cDNA library by the yeast two-hybrid approach with Id2, a negative regulator of basic helix-loop-helix (bHLH) factors. Of the clones obtained, approximately one-third were the E2-2 bHLH transcription factor. Id2 and E2-2 were shown to interact in direct two-hybrid assays in yeast cells, as well as immunoprecipitation assays in mammalian cells. Immunohistochemical analysis demonstrated co-localization of both Id2 and E2-2 in placental trophoblasts. Co-transfection of JEG-3 cells with E2-2 and Id2, and a luciferase reporter construct under the control of the human chorionic gonadotropin alpha-subunit promoter revealed that E2-2 had a negative effect on CGalpha-subunit transcription, which could be relieved by overexpression of Id2. The library was in turn rescreened with E2-2, and Id2 and Id1 were essentially the only clones obtained. We conclude that Id2 is a primary binding partner for the bHLH transcription factor E2-2 in the human placenta.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Cells, Cultured
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Choriocarcinoma / metabolism
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Choriocarcinoma / pathology
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DNA-Binding Proteins / metabolism*
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Gene Library
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Glycoprotein Hormones, alpha Subunit / genetics
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Helix-Loop-Helix Motifs*
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Humans
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Immunoenzyme Techniques
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Immunoprecipitation
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Inhibitor of Differentiation Protein 2
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Luciferases / metabolism
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Placenta / physiology
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Promoter Regions, Genetic / genetics*
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Protein Subunits
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Repressor Proteins / metabolism*
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Saccharomyces cerevisiae
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TCF Transcription Factors
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Transcription Factor 7-Like 2 Protein
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Transcription Factors / metabolism*
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Transfection
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Trophoblasts / metabolism
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Trophoblasts / pathology
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Two-Hybrid System Techniques
Substances
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DNA-Binding Proteins
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Glycoprotein Hormones, alpha Subunit
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ID2 protein, human
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Inhibitor of Differentiation Protein 2
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Protein Subunits
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Repressor Proteins
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TCF Transcription Factors
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TCF7L2 protein, human
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Transcription Factor 7-Like 2 Protein
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Transcription Factors
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Luciferases