title: MiR-155 negatively regulates c-Jun expression at the post-transcriptional level in human dermal fibroblasts in vitro: implications in UVA irradiation-induced photoaging.
abstract: OBJECTIVE
  C-Jun plays a critical role in ultraviolet A (UVA) irradiation-induced photoaging. The exact mechanisms by which UVA irradiation up-regulates c-Jun expression in human dermal fibroblasts (HDFs) are still not completely understood. We undertook this study to investigate whether microRNA-155 (miR-155) directly regulates the expression of c-Jun in HDFs in vitro.
  
  
  METHODS
  Expression of c-Jun mRNA and protein and miR-155 in UVA-irradiated HDFs were detected using quantitative real-time RT-PCR and Western blotting. Luciferase reporter assays were performed to examine whether a miR-155 binding site in the 3'-untranslated region (3'-UTR) of the c-Jun gene is responsible for miR-155-mediated c-Jun regulation in HEK293A cells, and expression of c-Jun mRNA and protein in UVA non-exposed and exposed HDFs trasfected with a miR-155 mimic or a miR-155 inhibitor was detected by quantitative real-time RT-PCR and Western blotting.
  
  
  RESULTS
  Expression of miR-155 was markedly reduced and that of c-Jun mRNA and protein was significantly up-regulated in UVA-irradiated HDFs. Luciferase reporter assays indicated that c-Jun is a direct target of miR-155 in HEK293A cells. In both UVA non-exposed and exposed HDFs, miR-155 mimic decreased c-Jun protein levels, while miR-155 inhibitor increased c-Jun protein levels, but both had no effect on c-Jun mRNA expression, which suggest that miR-155-induced c-Jun inhibition occurs at the post-transcriptional level.
  
  
  CONCLUSIONS
  Our results demonstrate that miR-155 directly controls c-Jun expression in HDFs at the post-transcriptional level and might function as a protective miRNA in HDFs.
authors.affiliation: Department of Dermatology, the Second Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an.
authors.forename: Jianwen
authors.initials: J
authors.lastname: Song
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Zhensheng
authors.initials: Z
authors.lastname: Yang
authors.forename: Linli
authors.initials: L
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Su
authors.forename: Ning
authors.initials: N
authors.lastname: Lu
authors.forename: Zhenhui
authors.initials: Z
authors.lastname: Peng
mesh_terms: D020413:3' Untranslated Regions; D015153:Blotting, Western; D002470:Cell Survival; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D005786:Gene Expression Regulation; D017930:Genes, Reporter / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015595:Skin Aging / Q000528:radiation effects; D014162:Transfection; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D020413:3' Untranslated Regions; C524942:MIRN155 microRNA, human; D035683:MicroRNAs; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D008156:Luciferases