Regulation of fibronectin and metalloproteinase expression by Wnt signaling in rheumatoid arthritis synoviocytes.
OBJECTIVE
The enhanced release of extracellular matrix proteins by fibroblast-like synoviocytes (FLS) from rheumatoid arthritis (RA) patients is suggestive of joint remodeling. Because Wnt proteins play a critical role in joint development, we investigated whether up-regulated Wnt signaling plays a role in the enhanced synthesis of extracellular matrix proteins. The purpose of the present experiments was to determine the role of Wnt-1-like molecules in the expression of matrix proteins by RA FLS and to ascertain the effects of Wnt antagonists on RA FLS function and survival.


METHODS
Transfection with a reporter plasmid (TOPflash) was performed to assess whether Wnt signaling is active in RA FLS. Wnt signaling was up-regulated in normal FLS by transfection with a Wnt-1 expression plasmid and was down-regulated in RA FLS by transfection with dominant-negative lymphoid enhancer factor 1 (LEF-1)/T cell factor 4 (TCF-4) and secreted Frizzled receptor protein 1 (sFRP-1) expression plasmids. Recombinant sFRP-1 and anti-Wnt-1 antibody were also administered to RA FLS to block Wnt signaling.


RESULTS
RA FLS had constitutive activation of the canonical Wnt signaling pathway. Transfection of normal FLS with a Wnt-1 expression vector enhanced not only fibronectin, but also pro-matrix metalloproteinase 3 (proMMP-3) expression. In a complementary manner, interference with Wnt signaling using anti-Wnt-1 antibody, the Wnt antagonist sFRP-1, or dominant-negative vectors that inhibited the transcription factors TCF-4/LEF-1 blocked the expression of fibronectin by RA FLS and reduced cell survival. Anti-Wnt-1 antibody and sFRP-1 also blocked the expression of proMMP-3.


CONCLUSIONS
Our results indicate that the canonical Wnt pathway regulates fibronectin and metalloproteinase expression in RA FLS.
Sen
Malini
M
Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0663, USA. msen@ucsd.edu
Reifert
Jack
J
Lauterbach
Kevin
K
Wolf
Vladimir
V
Rubin
Jeffrey S
JS
Corr
Maripat
M
Carson
Dennis A
DA
D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D015536:Down-Regulation; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis; D005353:Fibronectins / Q000032:analysis*; D006801:Humans; D008666:Metalloendopeptidases / Q000032:analysis*; D015398:Signal Transduction / Q000502:physiology*; D013583:Synovial Membrane / Q000166:cytology*; D014162:Transfection; D015854:Up-Regulation
D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D008666:Metalloendopeptidases