Cross talk among Smad, MAPK, and integrin signaling pathways enhances adventitial fibroblast functions activated by transforming growth factor-beta1 and inhibited by Gax.
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)-beta1 and inhibited by Gax.


RESULTS
Cultured AFs were stimulated with Ad-Gax, TGF-beta1, and siRNA-Gax. Assays for AFs viabilities demonstrated that TGF-beta1 and siRNA-Gax enhanced AFs proliferative, migratory, and adherent abilities, whereas Gax counteracted TGF-beta1-activated actions. Flow cytometry revealed that TGF-beta1 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-beta1 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-beta1 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.
Liu
Ping
P
Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Shandong University Qilu Hospital, Jinan, Shandong, China.
Zhang
Cheng
C
Feng
Jin Bo
JB
Zhao
Yu Xia
YX
Wang
Xu Ping
XP
Yang
Jian Min
JM
Zhang
Ming Xiang
MX
Wang
Xing Li
XL
Zhang
Yun
Y
D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000378:metabolism; D001483:Base Sequence; D049109:Cell Proliferation; D002478:Cells, Cultured; D003238:Connective Tissue / Q000378:metabolism; D003239:Connective Tissue Cells / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D005347:Fibroblasts / Q000378:metabolism; D005822:Genetic Vectors; D018398:Homeodomain Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016023:Integrins / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D011817:Rabbits; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051785:Smad Proteins / Q000378:metabolism*; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*
D017931:DNA Primers; D018398:Homeodomain Proteins; D016023:Integrins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D051785:Smad Proteins; D053773:Transforming Growth Factor beta1