Insulin-like growth factor-I increases expression of the porcine P-450 cholesterol side chain cleavage gene through a GC-rich domain.
The promoter/regulatory region of the porcine P-450 cholesterol side chain cleavage (P450scc) gene was cloned from a porcine genomic library. This gene contains a GC-rich region (-130-100) that mediates insulin-like growth factor I (IGF-I) and cAMP stimulation of gene expression in porcine granulosa cells. Stimulation of gene expression by cAMP occurs in 6 h, while IGF-I stimulation occurs in 24-48 h. This region is also responsive to insulin but not fibroblast growth factor. The effects of IGF-I and cAMP on gene expression in porcine granulosa cells are additive. In Y1 adrenal cells, the same region is responsive to cAMP but not to IGF-I. Gel shift assays using an oligonucleotide of this region and nuclear extract protein from porcine granulosa and Y1 adrenal cells identified three DNA-protein complexes (C1-C3). The binding activity of the complexes did not change with IGF-I or forskolin treatment of granulosa cells. Mutational analysis results were consistent with IGF-I regulating gene expression through the C2 DNA protein complex. Moreover, this complex binds differently in gel shift assay to mutant oligonucleotides with porcine and Y1 and nuclear extract protein. We conclude that IGF-I stimulates porcine P450scc gene expression through a distinct, cell-specific protein complex binding to a GC-rich domain.
Urban
R J
RJ
Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555-1060.
Shupnik
M A
MA
Bodenburg
Y H
YH
D000311:Adrenal Glands / Q000166:cytology; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D002478:Cells, Cultured; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics*; D003001:Cloning, Molecular; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D017930:Genes, Reporter; D006107:Granulosa Cells / Q000166:cytology / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008969:Molecular Sequence Data; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013552:Swine; D014158:Transcription, Genetic; D014162:Transfection
D004268:DNA-Binding Proteins; D005576:Colforsin; D005346:Fibroblast Growth Factors; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP; D002786:Cholesterol Side-Chain Cleavage Enzyme