Effects of fungal statins on high-glucose-induced mouse mesangial cell hypocontractility may involve filamentous actin, t-complex polypeptide 1 subunit beta, and glucose regulated protein 78

Abstract

Glomerular hyperfiltration is associated with mesangial cell hypocontractility. How 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) influence mesangial cell contraction is unclear. We investigated the effect of statins on mesangial cell hypocontractility and identified candidate proteins and filamentous/globular (F/G)-actin involved in this process. A high-glucose-induced mouse mesangial cell hypocontractility model was treated with fungal statins, simvastatin (Sim), lovastatin (Lov), and pravastatin (Pra). The optimum statin dose was determined by an 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay and then applied to a cell model. A 2-dimensional gel/matrix-assisted laser desorption/ionization time-of-flight mass spectrometer analysis was used to evaluate protein expression cells incubated in the presence of a normal level of glucose (N), a high level of glucose (H), and a high level of glucose plus Sim (H + S). Candidate proteins were analyzed. Finally, the ratio of F/G actin in groups N, H, and H+S was evaluated. The MTT assay showed that Sim and Lov exerted dose- and time-related inhibition of proliferation of mesangial cells at N, but Pra had no effect. The optimum doses selected for Sim was 1 microM and for Lov was 3 microM, which were 1 increment before significant proliferation inhibition. Both doses reversed cell hypocontractility significantly, but Sim was chosen for further proteomic and F/G actin analyses. Proteomic analysis of groups N, H, and H + S showed that 18 proteins were involved in hypocontractility. These proteins were grouped and analyzed based on their known functions. Two selected proteins, TCP-1beta and GRP78, that were upregulated and downregulated, respectively, were confirmed by Western blot and immunohistochemistry. In regard to the F/G actin, group H had a significantly lower ratio than that of group N, and group H + S returned to a level similar to that of group N. In conclusion, Sim and Lov both seem to reverse mesangial cell hypocontractility. The process of Sim reversal of mesangial cell hypocontractility may involve F-actin, TCP-1beta, and GRP78.