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Protein kinase C activation increases the rate and magnitude of agonist-induced delta-opioid receptor down-regulation in NG108-15 cells.
Mol Pharmacol. 1992 Oct; 42(4):656-65.MP

Abstract

Protein kinase C (PKC) activation was examined for its role in delta-opioid receptor down-regulation in the neuroblastoma X glioma hybrid cell line NG108-15. Incubation of NG108-15 cells for 2 hr at 37 degrees with up to 1 microM 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA), a phorbol ester that activates PKC, had no effect on opioid binding to membranes prepared from these cells. However, as little as 3 nM PMA incubated with an opioid agonist and NG108-15 cells potentiated the decrease and the rate of decrease of opioid binding, compared with agonist alone. Scatchard analysis of [3H][D-Ala2,D-Leu5]enkephalin (DADLE) binding revealed that NG108-15 cells incubated for 3 hr with 1 nM DADLE and 30 nM PMA displayed a > 50% reduction in the number of [3H]DADLE binding sites with no affinity change at the remaining sites, compared with cells treated with DADLE alone. The antagonist naloxone blocked both DADLE-induced and PMA-enhanced DADLE-induced down-regulation. The agonists morphine and cyclazocine, which alone were unable to induce delta receptor down-regulation, did so in the presence of PMA. The PKC inhibitor staurosporine and down-regulation of PKC by chronic PMA treatment blocked PMA potentiation of DADLE-induced down-regulation, but not "normal" DADLE-induced down-regulation. The enhancement of down-regulation by PMA was unaffected by either metabolic inhibitor or incubations at 20 degrees, conditions that blocked down-regulation by DADLE alone. NG108-15 cells incubated with [3H]DADLE and PMA retained more [3H]DADLE than cells incubated with [3H]DADLE alone, suggesting that PMA enhanced receptor internalization instead of merely inhibiting membrane binding. The diacylglycerol 1-oleoyl-2-acetyl-glycerol and bradykinin substituted for PMA but not carbachol, indicating that PKC activated physiologically may play a role in delta receptor down-regulation.

Authors+Show Affiliations

Department of Pharmacology, University of Rochester, School of Medicine and Dentistry, New York 14642.No affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

1331757

Citation

Gucker, S, and J M. Bidlack. "Protein Kinase C Activation Increases the Rate and Magnitude of Agonist-induced Delta-opioid Receptor Down-regulation in NG108-15 Cells." Molecular Pharmacology, vol. 42, no. 4, 1992, pp. 656-65.
Gucker S, Bidlack JM. Protein kinase C activation increases the rate and magnitude of agonist-induced delta-opioid receptor down-regulation in NG108-15 cells. Mol Pharmacol. 1992;42(4):656-65.
Gucker, S., & Bidlack, J. M. (1992). Protein kinase C activation increases the rate and magnitude of agonist-induced delta-opioid receptor down-regulation in NG108-15 cells. Molecular Pharmacology, 42(4), 656-65.
Gucker S, Bidlack JM. Protein Kinase C Activation Increases the Rate and Magnitude of Agonist-induced Delta-opioid Receptor Down-regulation in NG108-15 Cells. Mol Pharmacol. 1992;42(4):656-65. PubMed PMID: 1331757.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Protein kinase C activation increases the rate and magnitude of agonist-induced delta-opioid receptor down-regulation in NG108-15 cells. AU - Gucker,S, AU - Bidlack,J M, PY - 1992/10/1/pubmed PY - 1992/10/1/medline PY - 1992/10/1/entrez SP - 656 EP - 65 JF - Molecular pharmacology JO - Mol Pharmacol VL - 42 IS - 4 N2 - Protein kinase C (PKC) activation was examined for its role in delta-opioid receptor down-regulation in the neuroblastoma X glioma hybrid cell line NG108-15. Incubation of NG108-15 cells for 2 hr at 37 degrees with up to 1 microM 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA), a phorbol ester that activates PKC, had no effect on opioid binding to membranes prepared from these cells. However, as little as 3 nM PMA incubated with an opioid agonist and NG108-15 cells potentiated the decrease and the rate of decrease of opioid binding, compared with agonist alone. Scatchard analysis of [3H][D-Ala2,D-Leu5]enkephalin (DADLE) binding revealed that NG108-15 cells incubated for 3 hr with 1 nM DADLE and 30 nM PMA displayed a > 50% reduction in the number of [3H]DADLE binding sites with no affinity change at the remaining sites, compared with cells treated with DADLE alone. The antagonist naloxone blocked both DADLE-induced and PMA-enhanced DADLE-induced down-regulation. The agonists morphine and cyclazocine, which alone were unable to induce delta receptor down-regulation, did so in the presence of PMA. The PKC inhibitor staurosporine and down-regulation of PKC by chronic PMA treatment blocked PMA potentiation of DADLE-induced down-regulation, but not "normal" DADLE-induced down-regulation. The enhancement of down-regulation by PMA was unaffected by either metabolic inhibitor or incubations at 20 degrees, conditions that blocked down-regulation by DADLE alone. NG108-15 cells incubated with [3H]DADLE and PMA retained more [3H]DADLE than cells incubated with [3H]DADLE alone, suggesting that PMA enhanced receptor internalization instead of merely inhibiting membrane binding. The diacylglycerol 1-oleoyl-2-acetyl-glycerol and bradykinin substituted for PMA but not carbachol, indicating that PKC activated physiologically may play a role in delta receptor down-regulation. SN - 0026-895X UR - https://www.unboundmedicine.com/medline/citation/1331757/Protein_kinase_C_activation_increases_the_rate_and_magnitude_of_agonist_induced_delta_opioid_receptor_down_regulation_in_NG108_15_cells_ L2 - http://molpharm.aspetjournals.org/cgi/pmidlookup?view=long&pmid=1331757 DB - PRIME DP - Unbound Medicine ER -