title: POMC and fibroblast biology.
abstract: We evidenced in vitro proopiomelanocortin (POMC) mRNA-transcription in human dermal fibroblasts using Northern blot hybridization. Modulation of POMC gene expression by cytokines (transforming growth factor-beta, TGF-beta, and tumor necrosis factor-alpha, TNF-alpha) was investigated by incubating human normal fibroblasts with 1 and 10 ng/ml cytokines, either alone or in combination, for 24 hours. Our results show that dermal fibroblasts express POMC at significant levels under unstimulated conditions. POMC steady-state levels were significantly reduced by addition of TGF-beta. On the other hand, TNF-alpha exerted a stimulatory effect on POMC mRNA transcription, partially counteracting the effect of TGF-beta. These data provide the first demonstration of POMC gene expression in cultured skin fibroblasts. The opposite regulatory effect of TGF-beta and TNF-alpha, two cytokines primarily involved in extracellular matrix regulation, suggests a possible role for POMC-derived peptides in fibroblast activity. We also investigated POMC mRNA expression in keloid-derived fibroblasts in culture, and its regulation by TGF-beta added at the highest concentration documented for inhibition. Keloid-derived fibroblasts showed clearly detectable levels of POMC mRNA in basal conditions, and no alteration of POMC gene expression was observed when TGF-beta was added in culture. The altered TGF-beta regulation of POMC mRNA levels suggest that POMC-derived peptides may play a role in the pathogenesis of keloid formation through an autocrine/paracrine network, resulting in modulation of extracellular matrix synthesis.
authors.affiliation: Department of Dermatology, University of Florence, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Lotti
authors.forename: P
authors.initials: P
authors.lastname: Teofoli
authors.forename: B
authors.initials: B
authors.lastname: Bianchi
authors.forename: A
authors.initials: A
authors.lastname: Mauviel
mesh_terms: D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007627:Keloid; D015603:Keratinocytes / Q000166:cytology / Q000502:physiology*; D007700:Kinetics; D011333:Pro-Opiomelanocortin / Q000235:genetics* / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology; D012879:Skin Physiological Phenomena; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D011333:Pro-Opiomelanocortin