Human dermal fibroblasts express prohormone convertases 1 and 2 and produce proopiomelanocortin-derived peptides

Abstract

In the last few years it has become apparent that the skin is a locoregional source for several proopio-melanocortin-derived peptides including a-melano-cyte-stimulating hormone, adrenocorticotropin, and b-endorphin. The enzymes that regulate expression of these neuropeptides are the prohormone convert-ases 1 and 2. In this study we demonstrate, by reverse transcriptase polymerase chain reaction and Western immunoblotting, that cultured human dermal fibroblasts express prohormone convertases 1 and 2 as well as 7B2, which is an essential cofactor for enzymatic activity of prohormone convertase 2. Immunofluorescence studies revealed prohormone convertase 1 to be mainly expressed in the peri-nuclear region in vesicular structures resembling the trans-Golgi network, whereas prohormone convertase 2 was found in the trans-Golgi network as well as in vesicular structures diffusely distributed in the peripheral cytoplasm. Expression of both enzymes was also confirmed in fibroblasts of normal adult human skin by immunohistochemistry using antibodies against prohormone convertases 1 and 2 and vimen-tin. To assess the relevance of prohormone convert-ase 1 and 2 expression in human dermal fibroblasts, we studied the expression of proopiomelanocortin and proopiomelanocortin-derived peptides. Proopio-melanocortin expression was detected by reverse transcriptase polymerase chain reaction and Western immunoblotting. α-Melanocyte-stimulating hormone, adrenocorticotropin, and β-endorphin were mainly located in vesicular structures as demonstrated by immunofluorescence. Production of these peptides was confirmed by radioimmunoassay, immunoradiometric assay, or enzyme immunoassay. Among several stimuli tested, interleukin-1 was found to upregulate production of α-melanocyte-stimulating hormone in human dermal fibroblasts. In summary, we have shown that human dermal fibroblasts express the enzymatic machinery for proopiomelanocortin processing and make proopio-melanocortin, α-melanocyte-stimulating hormone, adrenocorticotropin, and β-endorphin. Production of proopiomelanocortin peptides by human dermal fibroblasts may be relevant for fibroblast functions such as collagen degradation and/or regulation of dermal immune responses. © 2001 Elsevier Science Ltd. All rights reserved.