title: Ultraviolet B-induced apoptosis of human skin fibroblasts involves activation of caspase-8 and -3 with increased expression of vimentin.
abstract: BACKGROUND
  After irradiation with a high dose of ultraviolet B (UVB), cells undergo apoptosis. Caspase-8 and -3 are key mediators of apoptosis in many cells. Vimentin, an important cytoskeleton component, can be cleaved by caspase-3, -6, -7 and -8. Cell apoptosis is promoted via caspase-triggered proteolysis of vimentin. In this study, we explored the roles of caspase-8 and -3 and the changes in vimentin expression in UVB-induced apoptosis of human dermal fibroblasts.
  
  
  METHODS
  Skin fibroblasts were irradiated with 150 mJ/cm(2) UVB and cell death was monitored by the 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-diphenytetrazoliumromide assay and Hoechst staining. Caspase-8 and -3 activities were detected by the caspase activity assay. Vimentin expression was assessed by immunofluorescence and Western blot.
  
  
  RESULTS
  Caspase-8 and -3 were activated by 150 mJ/cm(2) UVB irradiation. Caspase-8 and -3 activities changed in a time-dependent way after UVB irradiation to induce apoptosis of fibroblasts, and caspase-8 and -3 interacted with each other in this process. However, their substrate, vimentin, showed an enhanced expression over time after UVB irradiation.
  
  
  CONCLUSIONS
  UVB-triggered apoptosis of fibroblasts was dependent on the activation of caspase-8 and -3 with an increased expression of vimentin.
authors.affiliation: Department of Dermatology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Haoxiang
authors.initials: H
authors.lastname: Xu
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Shiguang
authors.initials: S
authors.lastname: Peng
authors.forename: Tao
authors.initials: T
authors.lastname: Qu
authors.forename: Baoxi
authors.initials: B
authors.lastname: Wang
mesh_terms: D017209:Apoptosis / Q000528:radiation effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism*; D053181:Caspase 8 / Q000378:metabolism*; D004789:Enzyme Activation; D005347:Fibroblasts / Q000201:enzymology; D005455:Fluorescent Antibody Technique; D006801:Humans; D012867:Skin / Q000166:cytology / Q000201:enzymology*; D014466:Ultraviolet Rays; D014746:Vimentin / Q000378:metabolism*
chemical_list: D014746:Vimentin; D053148:Caspase 3; D053181:Caspase 8