An activator protein-1 complex mediates epidermal growth factor regulation of equine glycoprotein alpha subunit expression in trophoblast cells.
Equids and primates are the only species known to express the placental hormone chorionic gonadotropin (CG). CG is a member of the heterodimeric glycoprotein family and is composed of an alpha subunit linked to a hormone-specific beta subunit. Previously, we have reported that epidermal growth factor (EGF) regulates the equine glycoprotein hormone alpha subunit promoter through a protein kinase C (PKC)/mitogen-activated protein kinase (MAPK) signal transduction pathway in trophoblasts. The current study investigates the regulatory element/factors involved in the induction of equine glycoprotein alpha subunit gene expression by EGF. Using 5' deletion mutagenesis, we have delineated the primary EGF/PKC responsive region of the equine alpha subunit gene to be located between -2039 to -2032 base pairs upstream of the transcriptional start site. The sequence within this region contains an activator protein 1 (AP-1)-like response element (TGAATCA) and is similar to a consensus AP-1 (TGAC/GTCA) response element. This element appeared to preferentially interact with a c-fos/JunD heterodimer. Stimulation by EGF induced the binding of c-fos and JunD to this element and subsequently elevated promoter activity. In conclusion, an EGF/PKC/MAPK signal transduction pathway regulates equine glycoprotein alpha subunit gene expression through a distinct regulatory element(s) that lies between -2039 to -2032 of the equine glycoprotein alpha subunit promoter in trophoblasts and involves an AP-1 complex.
Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160-7401, USA.
Theingi M
TM
Thway
Michael W
MW
Wolfe
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002822:Choriocarcinoma; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics*; D006736:Horses / Q000235:genetics*; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D020218:Response Elements; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000378:metabolism* / Q000494:pharmacology; D014162:Transfection; D014327:Trophoblasts / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D015292:Glycoprotein Hormones, alpha Subunit; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D004815:Epidermal Growth Factor; D004247:DNA; D019908:Proto-Oncogene Proteins c-raf; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases