on January 10, 2008
Published online before print January 10, 2008, doi: 10.1161/ATVBAHA.107.159889
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Submitted on July 17, 2007
Accepted on December 31, 2007
Cross-Talk Among Smad, MAPK, and Integrin Signaling Pathways Enhances Adventitial Fibroblast Functions Activated by Transforming Growth Factor–
1 and Inhibited by Gax
Ping Liu ;
From the Key Laboratory of Cardiovascular Remodeling and Function Research (P.L., C.Z., J.B.F., Y.X.Z., X.P.W., J.M.Y., M.X.Z., Y.Z.), Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, Jinan, Shandong, China; the Second Hospital of Shandong University (P.L.), Jinan, Shandong, China; and the Texas Heart Institute at St Luke’s Episcopal Hospital (X.L.W.), Division of Cardiothoracic Surgery, Michael DeBakey Department of Surgery, Baylor College of Medicine, Houston, Tex.
* To whom correspondence should be addressed. E-mail: zhangyun{at}sdu.edu.cn.
Objective—We investigated whether Smad, mitogen-activated protein kinase (MAPK), and integrin signaling pathways cross-talk to enhance adventitial fibroblast (AF) bioactivity, which was activated by transforming growth factor (TGF)-
1 and inhibited by Gax.
Methods and Results—Cultured AFs were stimulated with Ad-Gax, TGF-1, and siRNA-Gax. Assays for AFs viabilities demonstrated that TGF-1 and siRNA-Gax enhanced AFs proliferative, migratory, and adherent abilities, whereas Gax counteracted TGF-1–activated actions. Flow cytometry revealed that TGF-1 and siRNA-Gax increased S phase cells; however, Gax decreased AFs in the S phase and increased those in the G0-G1 and apoptotic phases. RT-PCR, Western blotting, and immunocytochemistry showed that TGF-1 and siRNA-Gax upregulated the expression of cytokines in Smad, MAPK, and integrin signaling pathways, and downregulated that of p15, p16, and p21. Conversely, Gax induced downregulation of these cytokines and upregulation of p15, p16, and p21. Thus, these signaling pathways cross-talk to enhance AF bioactivity; Gax effectively counteracts TGF-1 effects, blocks the cross-talk of these pathways, inhibits AF functions, and increases AF apoptosis.
Conclusions—Our findings indicate that cross-talk among Smad, MAPK, and integrin signaling pathways may account mainly for the mechanism of AF functions. Gax is a promising therapeutic gene for dissecting the signaling pathways controlling AF bioactivities.
Key words: adventitial fibroblast • signaling pathway • cell function • TGF-
1 •
Gax