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| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Evaul, Kristen Hammes, Stephen R. |
| Description | Author Affiliation: Evaul K ( Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8857, USA.) |
| Abstract | Gonadal steroid production is stimulated by gonadotropin binding to G protein-coupled receptors (GPCRs). Although GPCR-mediated increases in intracellular cAMP are known regulators of steroidogenesis, the roles of other signaling pathways in mediating steroid production are not well characterized. Recent studies suggest that luteinizing hormone (LH) receptor activation leads to trans-activation of epidermal growth factor (EGF) receptors in the testes and ovary. This pathway is critical for LH-induced steroid production in ovarian follicles, probably through matrix metalloproteinase (MMP)-mediated release of EGF receptor (EGFR) binding ectodomains. Here we examined LH and EGF receptor cross-talk in testicular steroidogenesis using mouse MLTC-1 Leydig cells. We demonstrated that, similar to the ovary, trans-activation of the EGF receptor was critical for gonadotropin-induced steroid production in Leydig cells. LH-induced increases in cAMP and cAMP-dependent protein kinase (PKA) activity mediated trans-activation of the EGF receptor and subsequent mitogen-activated protein kinase (MAPK) activation, ultimately leading to StAR phosphorylation and mitochondrial translocation. Steroidogenesis in Leydig cells was unaffected by MMP inhibitors, suggesting that cAMP and PKA trans-activated EGF receptors in an intracellular fashion. Interestingly, although cAMP was always needed for steroidogenesis, the EGFR/MAPK pathway was activated and necessary only for early (30-60 min), but not late (120 min or more), LH-induced steroidogenesis in vitro. In contrast, 36-h EGF receptor inhibition in vivo significantly reduced serum testosterone levels in male mice, demonstrating the physiologic importance of this cross-talk. These results suggest that GPCR-EGF receptor cross-talk is a conserved regulator of gonadotropin-induced steroidogenesis in the gonads, although the mechanisms of EGF receptor trans-activation may vary. |
| ISSN | 00219258 |
| e-ISSN | 1083351X |
| Journal | Journal of Biological Chemistry |
| Issue Number | 41 |
| Volume Number | 283 |
| Language | English |
| Publisher | American Society for Biochemistry and Molecular Biology (United States) |
| Publisher Date | 2008-10-10 |
| Publisher Place | United States |
| Access Restriction | Open |
| Subject Keyword | Gonadotropins Pharmacology Leydig Cells Metabolism MAP Kinase Signaling System Drug Effects Receptor, Epidermal Growth Factor Receptors, LH Testosterone Biosynthesis Animals Cell Line Cyclic AMP-Dependent Protein Kinases Extracellular Signal-Regulated MAP Kinases Cytology Physiology Metalloproteases Antagonists & Inhibitors Mice Mitochondria Ovary Phosphoproteins Phosphorylation Protease Inhibitors Protein Structure, Tertiary Protein Transport Receptor Aggregation Time Factors Transcriptional Activation Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Biochemistry Molecular Biology |
| Content Type | Text |
| Resource Type | Article |
| Subject | Cell Biology Biochemistry Molecular Biology |
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