title: MicroRNAs and potential target interactions in psoriasis.
abstract: BACKGROUND
  Psoriasis is a chronic inflammatory skin disease often seen in patients with a genetic susceptibility. MicroRNAs (miRNA) are endogenous, short RNA molecules that can bind to parts of mRNA target genes, thus inhibiting their translation and causing accelerated turnover or transcript degradation. MicroRNAs are important in the pathogenesis of human diseases such as immunological disorders, as they regulate a broad range of biological processes.
  
  
  OBJECTIVE
  We investigated miRNA-mRNA interactions in involved (PP) and non-involved (PN) psoriatic skin compared with healthy skin (NN).
  
  
  METHODS
  Biopsies were obtained from PP, PN and NN, the miRNA and mRNA expression was analyzed by microarray techniques and a subset of miRNAs and mRNAs were validated by q-RT-PCR. Novel target interactions in psoriasis were found using PubMed, miRBase and RNAhybrid. In addition, TIMP3 protein expression was studied in PP, PN and NN. Finally, the miR-221/2-TIMP3 target interaction was studied in primary human keratinocytes by endogenous overexpression of the miRNAs.
  
  
  RESULTS
  We identified 42 upregulated miRNAs and 5 downregulated miRNAs in PP compared with NN, and only few deregulated miRNAs in PN compared with NN. Based on the miRNA and mRNA profiles miR-21, -205, -221 and -222 were found to have the following potential mRNA targets in psoriatic skin: PDCD4, TPM1, P57, C-KIT, RTN4, SHIP2, TIMP3, RECK and NFIB. The identified target mRNAs were likely to be involved in cellular growth, proliferation, apoptosis and degradation of the extracellular matrix. Finally we found that TIMP3 is downregulated in psoriatic skin. In vitro overexpression of miR-221 and miR-222 lead to degradation of TIMP3 resulting in decreased TIMP3 protein level.
  
  
  CONCLUSIONS
  Our data indicate several novel important associations for miRNAs in psoriasis and in particular the miR-221/2-TIMP3 target interaction could among others play a role in the psoriasis pathogenesis.
authors.affiliation: Department of Dermato-Allergology, Gentofte Hospital, University of Copenhagen, Niels Andersens Vej 65, 2900 Hellerup, Denmark. johnzibert@gmail.com
authors.forename: John R
authors.initials: JR
authors.lastname: Zibert
authors.forename: Marianne B
authors.initials: MB
authors.lastname: Løvendorf
authors.forename: Thomas
authors.initials: T
authors.lastname: Litman
authors.forename: Jørgen
authors.initials: J
authors.lastname: Olsen
authors.forename: Bogumil
authors.initials: B
authors.lastname: Kaczkowski
authors.forename: Lone
authors.initials: L
authors.lastname: Skov
mesh_terms: D000328:Adult; D017209:Apoptosis / Q000235:genetics; D001706:Biopsy; D002478:Cells, Cultured; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000502:physiology*; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D011565:Psoriasis / Q000209:etiology / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology; D055815:Young Adult
chemical_list: D035683:MicroRNAs; D012333:RNA, Messenger; D019717:Tissue Inhibitor of Metalloproteinase-3; C525709:MIR221, human; C525710:MIR222, human; C088390:TIMP3 protein, human