Smad7 alleviates glomerular mesangial cell proliferation via the ROS-NF-κB pathway

Objective: The aim of this study was to demonstrate that altered gene expression of Smad7regulated NF-kappa B expression and ROS production on Ang II (Angiotensin II)-induced rat glomerular mesangial cell (GMC) proliferation. Methods: pAdTrack-CMV-Smad7 was transduced into rat GMC by adeno-transduction using an ADV (adenovirus)-mediated vector in vivo. Diphenylene iodonium chloride (DPI) pre-treated GMC, and blocked ROS generation as determined by DCFH-DA method. Altered expressions of I kappa B alpha and p65 were monitored by Western blot analysis and immunofluorescence. GMC proliferation was tested by the Cell Counting Kit-8 assay. Apoptosis of GMC was detected by flow cytometric analysis. Results: Over-expression of Smad7 dampened the ability of Ang II to promote ROS synthesis and inhibited the ability of Ang II to decrease functional expression of I kappa B alpha. Moreover, Smad7 increased nuclear I kappa B alpha expression. Smad7 did not significantly influence the capacity of Ang II to increase protein expression of NF-kappa B p65. However, immunofluorescence analysis showed that Smad7 reduced nuclear NF-kappa B. p65 level. Further, over expression of Smad7 promoted GMC apoptosis by inhibiting NF-kappa B activation, which alleviated the Ang II promoted proliferation of GMC. Conclusions: Smad7 influenced NF-kappa B expression by regulating ROS generation, and induced GMC apoptosis to counter the Ang II-promoted proliferation.