Abstract
The ligand-induced down-regulation of LH receptor (LHR) expression in the ovaries, at least in part, is regulated by a posttranscriptional process mediated by a specific LH receptor mRNA binding protein (LRBP). The LH-mediated signaling pathways involved in this process were examined in primary cultures of human granulosa cells. Treatment with 10 IU human chorionic gonadotropin (hCG) for 12 h resulted in the down-regulation of LHR mRNA expression while producing an increase in LHR mRNA binding to LRBP as well as a 2-fold increase in LRBP levels. The activation of ERK1/2 pathway in LH-mediated LHR mRNA down-regulation was also established by demonstrating the translocation of ERK1/2 from the cytosol to the nucleus using confocal microcopy. Inhibition of protein kinase A using H-89 or ERK1/2 by U0126 abolished the LH-induced LHR mRNA down-regulation. These treatments also abrogated both the increases in LRBP levels as well as the LHR mRNA binding activity. The abolishment of the hCG-induced increase in LRBP levels and LHR mRNA binding activity was further confirmed by transfecting granulosa cells with ERK1/2 specific small interfering RNA. This treatment also reversed the hCG-induced down-regulation of LHR mRNA. These data show that LH-regulated ERK1/2 signaling is required for the LRBP-mediated down-regulation of LHR mRNA.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Blotting, Western
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Butadienes / pharmacology
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Cell Line
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Cell Nucleus / metabolism
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Chorionic Gonadotropin / pharmacology
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Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
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Cyclic AMP-Dependent Protein Kinases / metabolism
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Down-Regulation*
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Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
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Extracellular Signal-Regulated MAP Kinases / genetics
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Extracellular Signal-Regulated MAP Kinases / metabolism*
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Female
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Fluorescent Antibody Technique
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Granulosa Cells / metabolism
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Humans
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Isoquinolines / pharmacology
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Microscopy, Confocal
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Nitriles / pharmacology
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Ovary
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Phosphotransferases (Alcohol Group Acceptor) / genetics
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Phosphotransferases (Alcohol Group Acceptor) / metabolism*
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Polymerase Chain Reaction
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RNA Processing, Post-Transcriptional
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RNA, Messenger / genetics*
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RNA, Small Interfering / pharmacology
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Receptors, LH / genetics*
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Receptors, LH / metabolism
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Signal Transduction
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Sulfonamides / pharmacology
Substances
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Butadienes
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Chorionic Gonadotropin
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Isoquinolines
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Nitriles
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RNA, Messenger
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RNA, Small Interfering
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Receptors, LH
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Sulfonamides
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U 0126
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Phosphotransferases (Alcohol Group Acceptor)
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mevalonate kinase
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Cyclic AMP-Dependent Protein Kinases
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Extracellular Signal-Regulated MAP Kinases
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N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide