A transformed murine Leydig cell line expresses the ETA receptor subtype.
We recently demonstrated that transformed murine Leydig cells (MA-10) responded to endothelin-1 (ET-1) via increased steroidogenesis. This study addresses the endothelin receptor subtype present on this cell line and whether or not the cells produce ET-1. The expression of the preproendothelin-1 (PPET-1) gene was investigated by Northern blot analysis, and PPET-1 mRNA was found to be < 0.2% of that present in pulmonary endothelial cells. The medium from MA-10 cells, maintained under serum-free conditions, was analyzed by radio-immunoassay to determine immunoreactive-ET-1 production and ET-1 levels were found to be below the sensitivity of the assay (< 10 pg/ml). The data from competitive binding experiments with [125I]ET-1 and unlabeled ET-1, ET-3 and receptor subtype selective ligands yielded a single class of high affinity binding sites with ETA receptor subtype characteristics. The results of this study demonstrate that MA-10 cells possess the ETA receptor subtype but do not produce significant quantities of ET-1 under basal conditions.
Department of Biochemistry, University of Georgia, Athens 30602.
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Ergul
M K
MK
Glassberg
M E
ME
Freeman
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D
Puett
D000818:Animals; D001667:Binding, Competitive; D002461:Cell Line, Transformed; D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D016232:Endothelins / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D017466:Receptors, Endothelin / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics
D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D016232:Endothelins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D017466:Receptors, Endothelin