title: PPARdelta enhances keratinocyte proliferation in psoriasis and induces heparin-binding EGF-like growth factor.
abstract: Psoriasis is a common skin disease involving keratinocyte proliferation and altered differentiation, as well as T-cell activation. Here, we show that altered gene transcription in psoriatic skin lesions is highly reproducible between independent data sets. Analysis of gene expression confirmed dysregulation in all expected functional categories, such as IFN signaling and keratinocyte differentiation, and allowed molecular fingerprinting of a previously characterized dendritic cell subset associated with psoriasis tumor necrosis factor alpha (TNF-alpha)- and inducible nitric oxide synthase (iNOS)-producing CD11b(INT) DC (Tip-DC). Unexpectedly, a large group of dysregulated transcripts was related to fatty acid signaling and adipocyte differentiation, exhibiting a pattern consistent with the activation of peroxisome proliferator-activated receptor delta (PPARdelta). PPARdelta itself was strongly induced in psoriasis in vivo. In primary keratinocytes, PPARdelta was induced by the transcription factor activator protein 1, in particular by junB, but not by canonical WNT signaling, in contrast to its regulation in colon carcinoma cells. Activation of PPARdelta enhanced proliferation of keratinocytes, while this was inhibited by knockdown of PPARdelta. Finally, heparin-binding EGF-like growth factor (HB-EGF), known to induce epidermal hyperplasia and itself overexpressed in psoriasis, was identified as a direct target gene of PPARdelta. The present data suggest that activation of PPARdelta is a major event in psoriasis, contributing to the hyperproliferative phenotype by induction of HB-EGF.
authors.affiliation: Department of Biology, Free University of Berlin, Berlin, Germany.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Romanowska
authors.forename: Nadya
authors.initials: N
authors.lastname: al Yacoub
authors.forename: Henrik
authors.initials: H
authors.lastname: Seidel
authors.forename: Susanne
authors.initials: S
authors.lastname: Donandt
authors.forename: Hannah
authors.initials: H
authors.lastname: Gerken
authors.forename: Sandra
authors.initials: S
authors.lastname: Phillip
authors.forename: Nathalie
authors.initials: N
authors.lastname: Haritonova
authors.forename: Metin
authors.initials: M
authors.lastname: Artuc
authors.forename: Susann
authors.initials: S
authors.lastname: Schweiger
authors.forename: Wolfram
authors.initials: W
authors.lastname: Sterry
authors.forename: John
authors.initials: J
authors.lastname: Foerster
mesh_terms: D049109:Cell Proliferation; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D066257:Heparin-binding EGF-like Growth Factor; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D015603:Keratinocytes / Q000473:pathology*; D016328:NF-kappa B / Q000032:analysis; D047494:PPAR delta / Q000032:analysis / Q000502:physiology*; D020033:Protein Isoforms; D011565:Psoriasis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000378:metabolism
chemical_list: D005227:Fatty Acids; C587883:HBEGF protein, human; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D016328:NF-kappa B; D047494:PPAR delta; D020033:Protein Isoforms; D018808:Transcription Factor AP-1