CCN2 is necessary for adhesive responses to transforming growth factor-beta1 in embryonic fibroblasts.
CCN2 is induced by transforming growth factor-beta (TGFbeta) in fibroblasts and is overexpressed in connective tissue disease. CCN2 has been proposed to be a downstream mediator of TGFbeta action in fibroblasts; however, the role of CCN2 in regulating this process unclear. By using embryonic fibroblasts isolated from ccn2-/- mice, we showed that CCN2 is required for a subset of responses to TGFbeta. Affymetrix genome-wide expression profiling revealed that 942 transcripts were induced by TGFbeta greater than 2-fold in ccn2+/+ fibroblasts, of which 345 were not induced in ccn2-/- fibroblasts, including pro-adhesive and matrix remodeling genes. Whereas TGFbeta properly induced a generic Smad3-responsive promoter in ccn2-/- fibroblasts, TGFbeta-induced activation of focal adhesion kinase (FAK) and Akt was reduced in ccn2-/- fibroblasts. Emphasizing the importance of FAK and Akt activation in CCN2-dependent transcriptional responses to TGFbeta in fibroblasts, CCN2-dependent transcripts were not induced by TGFbeta in fak-/- fibroblasts and were reduced by wortmannin in wild-type fibroblasts. Akt1 overexpression in ccn2-/- fibroblasts rescued the TGFbeta-induced transcription of CCN2-dependent mRNA. Finally, induction of TGFbeta-induced fibroblast adhesion to fibronectin and type I collagen was significantly diminished in ccn2-/- fibroblasts. Thus in embryonic fibroblasts, CCN2 is a necessary cofactor required for TGFbeta to activate the adhesive FAK/Akt/phosphatidylinositol 3-kinase cascade, FAK/Akt-dependent genes, and adhesion to matrix.
Centre for Rheumatology, Department of Medicine, University College London (Royal Free Campus), London NW3 2PF, United Kingdom.
Xu
X
Shi-wen
Lee Anne
LA
Stanton
Laura
L
Kennedy
Daphne
D
Pala
Yunliang
Y
Chen
Sarah L
SL
Howat
Elisabetta A
EA
Renzoni
David E
DE
Carter
George
G
Bou-Gharios
Richard J
RJ
Stratton
Jeremy D
JD
Pearson
Frank
F
Beier
Karen M
KM
Lyons
Carol M
CM
Black
David J
DJ
Abraham
Andrew
A
Leask
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion; D003094:Collagen / Q000737:chemistry / Q000378:metabolism; D055513:Connective Tissue Growth Factor; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D017874:Immediate-Early Proteins / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D053773:Transforming Growth Factor beta1; D000077191:Wortmannin
D000730:Androstadienes; D003094:Collagen; D055513:Connective Tissue Growth Factor; D004791:Enzyme Inhibitors; D005353:Fibronectins; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D012313:RNA; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D000077191:Wortmannin; C526318:CCN2 protein, mouse; C508961:Tgfb1 protein, mouse