Pro-opiomelanocortin messenger ribonucleic acid and posttranslational processing of beta endorphin in spleen macrophages

• Published in: The Journal of clinical investigation 1986-06, Vol.77 (6), p.1776-1779
• Main Authors: LOLAIT, S. J, CLEMENTS, J. A, MARKWICK, A. J, CHENG, C, MCNALLY, M, SMITH, A. I, FUNDER, J. W
• Format: Article
• Language: English
• Subjects: Analysis of the immune response. Humoral and cellular immunity; Animals; Applied sciences; beta-Endorphin; Biological and medical sciences; Chromatography, High Pressure Liquid; DNA - analysis; Endorphins - biosynthesis; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Immunobiology; Macrophages - metabolism; Male; Mice; Mice, Inbred BALB C; Miscellaneous; Nucleic Acid Hybridization; Other techniques and industries; Poly A - metabolism; Pro-Opiomelanocortin - genetics; Protein Processing, Post-Translational; Regulatory factors and their cellular receptors; RNA - metabolism; RNA, Messenger - metabolism; Spleen - cytology
• ISSN: 0021-9738; 1558-8238
• DOI: 10.1172/JCI112501

We have previously demonstrated low levels of immunoreactive (ir)-beta-endorphin (beta-EP) and ir-ACTH in a subpopulation of mouse spleen macrophages, which is consistent with an involvement of opioid peptides in modulation of immune responses. Gel chromatography studies suggested the presence of an approximately 3.5,000-molecular weight (mol wt) species, putatively beta-EP, an approximately 11.5,000-mol-wt species, putatively beta-lipotropin, and a higher molecular weight species (putative beta-EP precursor, pro-opiomelanocortin (POMC). In this study we have extended our original findings by demonstrating the presence of messenger RNA for POMC by the use of a complementary DNA probe and Northern blot analysis of extracts of mouse and rat spleen. In addition, using high performance liquid chromatography (HPLC), we have shown that the major endorphin species in mouse spleen macrophages is beta-EP1-31, and that there are smaller amounts of each of the acetylated forms, N-acetyl-beta-EP1-16 (alpha-endorphin), N-acetyl-beta-EP1-17 (gamma-endorphin), N-acetyl-beta-EP1-27, and N-acetyl-beta-EP1-31. We interpret these studies as showing that (a) the spleen is an organ of POMC synthesis and that (b) the predominant COOH-terminal product of macrophage POMC is the opiate-receptor active species beta-EP1-31.