Evidence for altered Wnt signaling in psoriatic skin.
The Wnt gene family encodes a set of highly conserved secreted signaling proteins that have major roles in embryogenesis and tissue homeostasis. Yet the expression of this family of important mediators in psoriasis, a disease characterized by marked changes in keratinocyte growth and differentiation, is incompletely understood. We subjected 58 paired biopsies from lesional and uninvolved psoriatic skin and 64 biopsies from normal skin to global gene expression profiling. WNT5A transcripts were upregulated fivefold in lesional skin, accompanied by increased Wnt-5a protein levels. Notably, WNT5A mRNA was markedly induced by IL-1alpha, tumor necrosis factor-alpha, IFN-gamma, and transforming growth factor-alpha in cultured keratinocytes. Frizzled 2 (FZD2) and FZD5, which encode receptors for Wnt5A, were also increased in lesional psoriatic skin. In contrast, expression of WIF1 mRNA, encoding a secreted antagonist of the Wnt proteins, was downregulated >10-fold in lesional skin, along with decreased WNT inhibitory factor (WIF)-1 immunostaining. Interestingly, pathway analysis along with reduced AXIN2 expression and lack of nuclear translocation of beta-catenin indicated a suppression of canonical Wnt signaling in lesional skin. The results of our study suggest a shift away from canonical Wnt signaling toward noncanonical pathways driven by interactions between Wnt-5a and its cognate receptors in psoriasis, accompanied by impaired homeostatic inhibition of Wnt signaling by WIF-1 and dickkopf.
Gudjonsson
Johann E
JE
Department of Dermatology, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA. johanng@med.umich.edu
Johnston
Andrew
A
Stoll
Stefan W
SW
Riblett
Mary B
MB
Xing
Xianying
X
Kochkodan
James J
JJ
Ding
Jun
J
Nair
Rajan P
RP
Aphale
Abhishek
A
Voorhees
John J
JJ
Elder
James T
JT
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D001706:Biopsy; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D015536:Down-Regulation / Q000502:physiology; D051157:Frizzled Receptors / Q000235:genetics; D020869:Gene Expression Profiling; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism*; D011565:Psoriasis / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D012333:RNA, Messenger / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology; D051153:Wnt Proteins / Q000235:genetics* / Q000378:metabolism*; D000071818:Wnt-5a Protein
D048868:Adaptor Proteins, Signal Transducing; D016207:Cytokines; C501126:DKK1 protein, human; C489742:FZD2 protein, human; C498589:FZD5 protein, human; D051157:Frizzled Receptors; D036341:Intercellular Signaling Peptides and Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D012097:Repressor Proteins; C485569:WIF1 protein, human; C085389:WNT5A protein, human; D051153:Wnt Proteins; D000071818:Wnt-5a Protein