A co-culture system reveals the involvement of intercellular pathways as mediators of the lutropin receptor (LHR)-stimulated ERK1/2 phosphorylation in Leydig cells.
Co-cultures of lutropin receptor (LHR) positive and negative Leydig cells were used to test the hypothesis that the LHR provokes phosphorylation of the extracellular regulated kinases (ERK1/2) using intracellular and intercellular pathways. Addition of hCG to MA-10 cells (LHR positive) stimulates phosphorylation of the EGF receptor (EGFR) and ERK1/2 whereas addition of hCG to I-10 cells (LHR negative) does not. Addition of hCG to co-cultures of MA-10 and I-10 cells rapidly stimulates the phosphorylation of the EGFR and ERK1/2 in I-10 cells, however. Transfection of interfering constructs shows that the LHR-mediated activation of Fyn in MA-10 cells is necessary for the phosphorylation of the EGFR and ERK1/2 in I-10 cells. This pathway can also be demonstrated in MA-10 cells but the phosphorylation of ERK1/2 in MA-10 cells also involves a second pathway mediated by protein kinase A (PKA). We propose that the LHR-mediated stimulation of the ERK1/2 cascade in Leydig cells depends on two independent pathways. One is intracellular and is mediated by PKA. The second is mediated by Fyn and it involves the release of soluble factors that act to phosphorylate the EGFR in an autocrine/paracrine fashion.
Shiraishi
Koji
K
Department of Pharmacology, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.
Ascoli
Mario
M
D000818:Animals; D019898:Autocrine Communication / Q000187:drug effects / Q000502:physiology; D002450:Cell Communication / Q000502:physiology; D045744:Cell Line, Tumor; D006063:Chorionic Gonadotropin / Q000493:pharmacokinetics / Q000494:pharmacology; D018920:Coculture Techniques; D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism; D066246:ErbB Receptors / Q000187:drug effects / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D007985:Leydig Cells / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051076:Proto-Oncogene Proteins c-fyn / Q000187:drug effects / Q000378:metabolism; D011974:Receptors, LH / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013737:Testis / Q000166:cytology / Q000378:metabolism*; D014162:Transfection
D006063:Chorionic Gonadotropin; D011974:Receptors, LH; D066246:ErbB Receptors; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3