title: Responses of the 27-kDa heat shock protein to UVB irradiation in human epidermal melanocytes.
abstract: Solar ultraviolet radiation (UVR) is a major environmental hazard for the skin, and UVB (280-320 nm) has been proposed to be a main factor for melanoma development. In response to sunlight exposure, the skin has adapted a number of innate resistance mechanisms. Among them is the small heat shock protein of 27 kDa (HSP27) known to play a role in the protection of cells from variety of environmental insults including UV irradiation. In this study, we demonstrated that UVB irradiation of cultured normal epidermal melanocytes initiates changes in HSP27 phosphorylation and localization. In unstressed melanocytes, HSP27 was present as the non-phosphorylated isoform. UVB irradiation with a physiological dose (7-25 mJ/cm(2)) resulted in the formation of a mono-phosphorylated isoform and sometimes a bi-phosphorylated isoform. The UVB-induced HSP27 phosphorylation was inhibited when melanocytes were treated with the antioxidant N-acetyl cysteine or inhibitor of p38 MAP kinase prior to UVB exposure, suggesting that UVB induced HSP27 phosphorylation through reactive oxygen species/p38 MAP kinase pathway. In response to UBV irradiation, HSP27 in melanocytes translocated from the cytoplasm to the nucleus. The HSP27 responses may provide some protective role against UVB-induced cell damage in the skin.
authors.affiliation: Department of Dermatology, University of California Davis School of Medicine, Davis, CA 95616, USA.
authors.forename: Biao
authors.initials: B
authors.lastname: Shi
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Grahn
authors.forename: Debra A
authors.initials: DA
authors.lastname: Reilly
authors.forename: Theresa C
authors.initials: TC
authors.lastname: Dizon
authors.forename: R Rivkah
authors.initials: RR
authors.lastname: Isseroff
mesh_terms: D002478:Cells, Cultured; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism / Q000528:radiation effects; D005786:Gene Expression Regulation / Q000528:radiation effects; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008544:Melanocytes / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D018832:Molecular Chaperones; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000528:radiation effects; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014466:Ultraviolet Rays; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D048051:p38 Mitogen-Activated Protein Kinases