Regulation of delta-opioid receptor mRNA levels by receptor-mediated and direct activation of the adenylyl cyclase-protein kinase A pathway.
The effects of activation of the adenylyl cyclase-protein kinase A pathway on the expression of delta-opioid receptor mRNA in the NG108-15 neuroblastoma x glioma cell line has been investigated. Activation of prostaglandin E1 (PGE1) receptors, which are positively coupled to adenylyl cyclase, resulted in a reduction in delta-receptor messenger RNA levels. Direct stimulation of adenylyl cyclase by forskolin or treatment of cells with the cyclic AMP analogue dibutyryl cyclic AMP (db-cAMP) mimicked the effect of PGE1. Down-regulation in receptor protein levels, as measured by loss of radioligand binding sites, was also observed and its extent correlated well with the decrease in the amount of delta-opioid receptor transcripts. D-Ser2-Leu-enkephalin-Thr6 (DSLET) inhibition of adenylyl cyclase activity was also diminished after db-cAMP treatment. Inhibitors of protein kinase A (PKA) partially reversed the PGE1- and db-cAMP-mediated repression of the delta-opioid receptor mRNA levels. The rate of degradation of delta-opioid receptor mRNA in the presence of actinomycin D was not altered in response to db-cAMP, suggesting that mRNA stability is not reduced by PKA action. The regulation of delta-opioid receptor mRNA levels by db-cAMP was not sensitive to the protein synthesis inhibitor cycloheximide, suggesting that de novo protein synthesis is not required in this process.
Buzas
B
B
Department of Pharmacology, Uniformed Services University, Bethesda, Maryland 20814, USA.
Rosenberger
J
J
Cox
B M
BM
D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D003994:Bucladesine / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004174:Diprenorphine / Q000378:metabolism / Q000494:pharmacology; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D051379:Mice; D009447:Neuroblastoma; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D017465:Receptors, Opioid, delta / Q000235:genetics*; D014316:Tritium; D014407:Tumor Cells, Cultured / Q000737:chemistry / Q000201:enzymology
D000067956:Adenylyl Cyclase Inhibitors; D000700:Analgesics; D015220:Calcium Channels; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D017465:Receptors, Opioid, delta; D014316:Tritium; D004174:Diprenorphine; D004743:Enkephalin, Leucine; D003994:Bucladesine; C034318:enkephalin, Ser(2), Leu(5), Thr(6)-; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases