PPARdelta enhances keratinocyte proliferation in psoriasis and induces heparin-binding EGF-like growth factor.
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.
Romanowska
Malgorzata
M
Department of Biology, Free University of Berlin, Berlin, Germany.
al Yacoub
Nadya
N
Seidel
Henrik
H
Donandt
Susanne
S
Gerken
Hannah
H
Phillip
Sandra
S
Haritonova
Nathalie
N
Artuc
Metin
M
Schweiger
Susann
S
Sterry
Wolfram
W
Foerster
John
J
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
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