title: In situ demonstration of phosphorylated c-jun and p38 MAP kinase in epidermal keratinocytes following ultraviolet B irradiation of human skin.
abstract: Ultraviolet B (UVB) irradiation is known to induce activation of cellular stress response pathways in cultured cells or intact human skin, as demonstrated by phosphorylation of MAP kinase family members and up- or down-stream targets, using biochemical assays. This study demonstrates by immunohistochemistry that low-dose UVB irradiation of normal human skin induces rapid and reversible phosphorylation of c-jun (a target of c-jun N-terminal kinase) and p38 mitogen activated protein kinase (p38 MAP kinase). Phosphorylation was maximal at 4-8 h and returned to normal levels at 48 h after irradiation. Nuclear localization of these phosphorylated substrates was found using antisera against the epitope containing the phosphorylated serine-73 of c-jun, and the dually phosphorylated epitope (threonine-180 and tyrosine-182) of p38 MAP kinase. Nearly all epidermal cells were positive for c-jun phosphorylation, whereas p38 phosphorylation was seen predominantly in the differentiated layers. In contrast to the massive activation of c-jun and p38, only a small population of the suprabasal cells showed nuclear translocation of nuclear factor kappa B (NFkappaB), and a few scattered cells became apoptotic, as determined by TUNEL (TdT mediated dUTP nick end labelling) staining. The expression of involucrin and skin-derived anti-leukoproteinase (SKALP)/elafin, two genes putatively under control of the c-jun and p38 pathways, was found to be increased. These findings establish the first cellular localization of UVB-induced protein phosphorylation of stress response proteins in human epidermis, thereby providing a link between cellular activation and gene expression in defined cell populations.
authors.affiliation: University Hospital Nijmegen, Department of Dermatology, PO Box 9101, 6500 HB Nijmegen, The Netherlands. R.Pfundt@derma.azn.nl
authors.forename: R
authors.initials: R
authors.lastname: Pfundt
authors.forename: I
authors.initials: I
authors.lastname: van Vlijmen-Willems
authors.forename: M
authors.initials: M
authors.lastname: Bergers
authors.forename: M
authors.initials: M
authors.lastname: Wingens
authors.forename: W
authors.initials: W
authors.lastname: Cloin
authors.forename: J
authors.initials: J
authors.lastname: Schalkwijk
mesh_terms: D000293:Adolescent; D000328:Adult; D002478:Cells, Cultured; D004307:Dose-Response Relationship, Radiation; D006360:Heat-Shock Proteins / Q000528:radiation effects; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D015603:Keratinocytes / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000528:radiation effects*; D016328:NF-kappa B / Q000528:radiation effects; D010766:Phosphorylation / Q000528:radiation effects; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism / Q000528:radiation effects*; D012867:Skin / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D014466:Ultraviolet Rays; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D006360:Heat-Shock Proteins; D016328:NF-kappa B; D016755:Proto-Oncogene Proteins c-jun; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases