Prostaglandin E2 induces up-regulation of murine macrophage beta-endorphin receptors.
Cultured murine bone marrow macrophages specifically bound 125I-labeled beta-endorphin. Binding was displaceable by 100 times molar excess of full-length beta-endorphin but was insensitive to the opioid receptor antagonist, naloxone. Binding was inhibited by beta-endorphin's C-terminal tetrapeptide, lys-lys-gly-glu, but not by the truncated N-terminal 27 amino acid fragment, indicating that binding of beta-endorphin to this receptor is dependent on its C-terminus. Macrophages incubated for 24 h with 10(-8)-10(-5) M prostaglandin E2 showed a dose-dependent increase in beta-endorphin binding, implying receptor up-regulation. This was also observed in response to the phosphodiesterase inhibitor, isobutylmethylxanthine, indicating that regulation of these receptors may be mediated through a cAMP-dependent process. This is the first demonstration that beta-endorphin receptor expression can be positively regulated.
Gelfand
R A
RA
Endocrinology Services, Department of Veterans Affairs Medical Center, Long Beach, CA 90822, USA.
Wepsic
H T
HT
Parker
L N
LN
Jadus
M R
MR
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D015232:Dinoprostone / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D009270:Naloxone / Q000494:pharmacology; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D011957:Receptors, Opioid / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*; D001615:beta-Endorphin / Q000031:analogs & derivatives / Q000378:metabolism
D010446:Peptide Fragments; D011957:Receptors, Opioid; D009270:Naloxone; D001615:beta-Endorphin; C035581:beta-endorphin (1-27); C035101:N-acetyl-beta-endorphin; D015232:Dinoprostone; D015056:1-Methyl-3-isobutylxanthine