title: Preventive effects of phosphorylated ascorbate on ultraviolet-B induced apoptotic cell death and DNA strand cleavage through enrichment of intracellular vitamin C in skin epidermal keratinocytes.
abstract: Mortality of mouse keratinocytes Pam212 that were irradiated with ultraviolet-B (UVB) was shown to be repressed by pre-irradiated administration with L-ascorbic acid (Asc) or more markedly with Asc-2-O-phosphate (Asc2P), but not with dehydroascorbic acid (DehAsc) or Asc-2-O-alpha-glucoside (Asc2G), although not repressed by post-irradiated administration. The cytoprotection by Asc2P was restricted against UVB below 5-20 mJ/cm2, and exhibited markedly by administration for a period over 2 h, which may be caused by intracellular Asc that was accumulated via dephosphorylation of Asc2P and was increased, 6-24 h after, to levels above twice as abundant as those of Asc-administration. Pre-irradiated Asc2P-administration slightly repressed a DNA ladder-like electrophoretic pattern for UVB-irradiated keratinocytes, containing the histone-bound DNA fragments as shown by ELISA assay, and appreciably repressed the DNA-3'OH cleavage terminals as shown by terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) stain. Thus, prevention of UVB-induced cell death by Asc2P was shown to occur concurrently with inhibition of DNA cleavages and enrichment of intracellular Asc.
authors.affiliation: Prefectural University of Hiroshima, Laboratory of Cell-Death Control BioTechnology, Faculty of Life and Environmental Sciences, Shobara, Hiroshima, 727-0023, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Sugimoto
authors.forename: Yoji
authors.initials: Y
authors.lastname: Okugawa
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Miwa
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects*; D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D019610:Cytoprotection; D004247:DNA / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects / Q000528:radiation effects; D020287:In Situ Nick-End Labeling; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D051379:Mice; D010766:Phosphorylation; D012867:Skin / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: C011669:ascorbate-2-phosphate; D004247:DNA; D001205:Ascorbic Acid