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Transcriptional regulation of human insulin receptor gene by the high‐mobility group protein HMGI(Y)
Author(s) -
BRUNETTI ANTONIO,
MANFIOLETTI GUIDALBERTO,
CHIEFARI EUSEBIO,
GOLDFINE IRA D.,
FOTI DANIELA
Publication year - 2001
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.00-0190com
Subject(s) - insulin receptor , grb10 , biology , 5 ht5a receptor , irs2 , microbiology and biotechnology , insulin , insulin like growth factor 1 receptor , receptor , insulin receptor substrate , nuclear receptor coactivator 2 , reporter gene , transcription factor , nuclear receptor , gene expression , gene , endocrinology , genetics , insulin resistance , growth factor
We have previously identified two closely related nuclear binding proteins that specifically interact with two unique functional AT‐rich sequences of the 5′ regulatory region of the human insulin receptor gene. Expression of these nuclear binding proteins increases during myocyte and adipocyte differentiation, and in other tissues appears to correlate with insulin receptor content. We have hypothesized, therefore, that insulin receptor expression in the insulin target tissues is regulated at least in part by these nuclear proteins. Here we show data on purification and biochemical characterization of these DNA binding proteins. Using a conventional chromatographic purification procedure combined with electrophoresis mobility shift assay and immunoblot analyses, a unique ~15 kDa protein, either identical to or highly related to the architectural transcription factor HMGI(Y), has now been identified, suggesting an essential role for HMGI(Y) in regulating insulin receptor gene transcription. Direct evidence of HMGI(Y) insulin receptor promoter interactions is provided by functional analysis with the CAT reporter gene and by hormone binding studies in cells expressing HMGI(Y) antisense RNA. In these experiments, antisense HMGI(Y) specifically inhibits insulin receptor promoter function and insulin receptor protein expression, indicating that HMGI(Y) is required for proper transcription of insulin receptor gene. Moreover, our data consistently support the hypothesis that a putative defect in this nuclear binding protein may cause insulin receptor dysfunction with subsequent impairment of insulin signaling and action.—Brunetti, A., Manfioletti, G., Chiefari, E., Goldfine, I. D., Foti, D. Transcriptional regulation of human insulin receptor gene by the high‐mobility group protein HMGI(Y). FASEB J. 15, 492‐500 (2001)