Persistent corticotropin-releasing factor(1) receptor desensitization and downregulation in the human neuroblastoma cell line IMR-32.
Brain corticotropin-releasing factor (CRF) systems integrate various responses to stress. Pathological responses to stress may result from errors in CRF receptor regulation in response to changes in synaptic CRF levels. To establish an in vitro model to study brain CRF receptors, we characterized the CRF-induced modulation of CRF(1) receptors in the human neuroblastoma cell line, IMR-32. Treatment with CRF decreased CRF(1) receptor binding and desensitized CRF-induced increases in cAMP. The decrease in binding had an EC(50) of approximately 10 nM, was maximal by 30 min, and was blocked by the CRF receptor antagonist [D-Phe(12), Nle(21,38), C(alpha)-MeLeu(37)]CRF(12-41). The desensitization was homologous as vasoactive intestinal polypeptide-induced increases in cAMP were unchanged, and elevation of cAMP did not alter CRF(1) receptor binding. Treatment with CRF for up to 24 h did not alter CRF(1) receptor mRNA levels, suggesting that a posttranscriptional mechanism maintains the decrease in receptor binding. Interestingly, recovery of CRF receptor binding and CRF-stimulated cAMP production was only partial following exposure to 100 nM CRF. In contrast, receptor binding recovered to control levels following exposure to 10 nM CRF. These data suggest that exposure to high doses of CRF result in permanent changes characterized by only partial recovery. Identifying the mechanisms underlying this partial recovery may provide insights into mechanisms underlying the acute and chronic effects of stress on CRF receptor regulation.
Roseboom
P H
PH
Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Boulevard, Madison, WI 53719, USA. roseboom@facstaff.wisc.edu
Urben
C M
CM
Kalin
N H
NH
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism; D029845:Amphibian Proteins; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D003346:Corticotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000242:Cyclic AMP / Q000096:biosynthesis; D015536:Down-Regulation / Q000187:drug effects*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000187:drug effects* / Q000235:genetics; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D010446:Peptide Fragments / Q000494:pharmacology; D036361:Peptide Hormones; D010455:Peptides / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D018019:Receptors, Corticotropin-Releasing Hormone / Q000096:biosynthesis / Q000187:drug effects* / Q000235:genetics; D015290:Second Messenger Systems / Q000187:drug effects; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology; D000099052:CRF Receptor, Type 1
D029845:Amphibian Proteins; C101531:CRF receptor type 2; D002352:Carrier Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D036361:Peptide Hormones; D010455:Peptides; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; C067925:corticotropin-releasing hormone(12-41), Phe(12)-Nle(21,38)-alpha-Me-Leu(37)-; C067133:corticotropin releasing factor-binding protein; D014660:Vasoactive Intestinal Peptide; D000099052:CRF Receptor, Type 1; C025727:sauvagine; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D001973:Bromodeoxyuridine; D015056:1-Methyl-3-isobutylxanthine