title: Proopiomelanocortin gene product regulation in keratinocytes.
abstract: Proopiomelanocortin (POMC) is the precursor for adrenocorticotropic hormone, melanocyte-stimulating hormones, beta-lipotropic hormone (beta LPH), and beta endorphin. These peptides can function as neurotransmitters, modulate immune responses, and affect melanogenesis. We investigated POMC expression and protein processing in normal human keratinocytes. On Northern blot analysis, the baseline expression of the 1.2-kb POMC transcript was upregulated by ultraviolet radiation (UVR) or by stimulation with interleukin-1 alpha (IL-1 alpha) or phorbol 12-tetradecanoate 13-acetate (TPA). On Western blot analysis, POMC, beta LPH, and beta-endorphin were detected in cell extracts under baseline conditions. beta LPH level increased substantially after UVR, IL-1 alpha, or TPA. Within 36 h after TPA stimulation, beta-endorphin became undetectable in cell extracts, coinciding with an increase of beta-endorphin-immunoreactive protein in the culture medium. Our data establish that keratinocytes synthesize POMC protein as well as its derivatives beta LPH and beta-endorphin, and that this process is modulated by TPA, IL-1A, and UVR. beta LPH and beta-endorphin of keratinocyte origin may thus be involved in melanogenesis and/or immunomodulation in the skin after sun exposure, and their release into the circulation may also have systemic effects.
authors.affiliation: Department of Dermatology, Boston University School of Medicine, Massachusetts 02118, USA.
authors.forename: M
authors.initials: M
authors.lastname: Wintzen
authors.forename: M
authors.initials: M
authors.lastname: Yaar
authors.forename: J P
authors.initials: JP
authors.lastname: Burbach
authors.forename: B A
authors.initials: BA
authors.lastname: Gilchrest
mesh_terms: D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D011333:Pro-Opiomelanocortin / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014466:Ultraviolet Rays; D001615:beta-Endorphin / Q000032:analysis
chemical_list: D007375:Interleukin-1; D012333:RNA, Messenger; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; D013755:Tetradecanoylphorbol Acetate