RGS3 inhibits TGF-β1/Smad signalling in adventitial fibroblasts

Recent evidence suggests that adventitial fibroblasts (AFs) are crucially implicated in atherosclerosis. However, the mechanisms by which AFs are dysfunctional and contribute to atherosclerosis remain unclear. This study aimed to investigate the role of regulator of G-protein signalling 3 (RGS3) in the regulation of AFs using apoE knockout mouse as the model. Pathological changes in aortic arteries of apoE knockout mice fed with hyperlipid diet were examined by Movat staining. The expression of RGS3, α-SMA, TGF-β1, Smad2, and Smad3 in the adventitia was detected by immunohistochemistry. Adventitial fibroblasts were isolated from aortic arteries of apoE knockout mice and infected with RGS3 overexpression lentivirus or empty lentivirus. The expression of RGS3, α-SMA, TGF-β1, Smad2, and Smad3 in AFs was detected by real-time polymerase chain reaction and Western blot analysis. We found that hyperlipidic diet caused significant aortic intima thickening and atherosclerotic plaques in 15-week-old apoE knockout mice. Compared to wild-type mice, RGS3 expression was lower while α-SMA, TGF-β1, Smad2, and Smad3 expression was higher in the adventitia of apoE knockout mice. In addition, lentivirus mediated overexpression of RGS3 caused decreased expression of α-SMA, TGF-β1, Smad2, and Smad3 in AFs derived from apoE(-/-) mice. In conclusion, these results suggest that RGS3 may provide protection against pathological changes of AFs and the development of atherosclerosis by inhibiting TGF-β1/Smad signalling. RGS3 may be a potential therapeutic target for atherosclerosis.