Characterization of a ultraviolet B-induced corticotropin-releasing hormone-proopiomelanocortin system in human melanocytes.
CRH, the main regulator of the systemic response to stress, is also expressed in the skin where it is incorporated into a local homolog of the hypothalamic-pituitary-adrenal axis. To investigate the mechanisms of the induction of the CRH-proopiomelanocortin (POMC) response in human melanocytes, we used UVB as an epidermal-specific stressor. Human normal melanocytes cultured in vitro were irradiated with graded doses of UVB, and the CRH-POMC responses were measured in cell extracts and/or supernatants. UVB stimulated the CRH promoter, the CRH mRNA expression, and peptide release. The UVB-induced stimulation of the CRH promoter was suppressed by pharmacological inhibitors of protein kinase A or by plasmid overexpressing a dominant mutant cAMP response element (CRE)-binding protein (CREB). UVB also stimulated phosphorylation of CREB, binding of phosphorylated CREB to CRE sites in the CRH promoter, and activity of the reporter gene construct driven by consensus CRE sites. Mutation in the CRE site in the CRH promoter rendered the corresponding reporter gene construct less responsive to UVB in both normal and malignant melanocytes. In addition to CRH effects, UVB activated the POMC promoter, POMC mRNA expression, and ACTH release, whereas an antagonist of the CRH receptor 1 abrogated the UVB-stimulated induction of POMC. In conclusion, UVB induces CRH production in human melanocytes through stimulation of the protein kinase A pathway, with sequential involvement of CRH-CRH receptor 1 in the stimulation of POMC expression.
Zbytek
Blazej
B
Department of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
Wortsman
Jacobo
J
Slominski
Andrzej
A
D015153:Blotting, Western; D050882:CREB-Binding Protein / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D017931:DNA Primers; D024202:Electrophoretic Mobility Shift Assay; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects*; D006801:Humans; D008544:Melanocytes / Q000378:metabolism* / Q000528:radiation effects; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation / Q000528:radiation effects; D011333:Pro-Opiomelanocortin / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000528:radiation effects*; D014466:Ultraviolet Rays
D017931:DNA Primers; D011333:Pro-Opiomelanocortin; D003346:Corticotropin-Releasing Hormone; D050882:CREB-Binding Protein; D017868:Cyclic AMP-Dependent Protein Kinases