Calhex₂₃₁ alleviates high glucose-induced myocardial fibrosis via inhibiting Itch-ubiquitin proteasome pathway in Vitro

抄録

Diabetic cardiomyopathy (DCM) is a major complication of diabetes, and features myocardial fibrosis as its main pathological feature. Calcium sensing receptor （CaSR）is a G protein-coupled receptor, which involves in myocardial fibrosis by regulation of calcium homeostasis. Calhex₂₃₁, the CaSR inhibitor, is not clear whether it regulates myocardial fibrosis in DCM. In the present study, type 1 diabetic(T1D) rats and primary neonatal rat cardiac fibroblasts were used to observe the role of Calhex₂₃₁. In vivo experiments showed that in the T1D group，contractile dysfunction and the deposition of collagen I and III were obvious after 12 weeks. In vitro experiments，we found that high glucose（HG）could increase the expression of CaSR, α-SMA, TGF-β₁, collagen I /III, MMP2, MMP9, along with cardiac fibroblast migration and proliferation. We further demonstrated that CaSR activation increased intracellular Ca²⁺ concentration and upregulated the expression of Itch (atrophin-1 interacting protein 4), which resulted in increasing the ubiquitination levels of Smad7 and upregulating the expression of p-Smad2, p-Smad3.However, treatment with Calhex₂₃₁clearly inhibited the above-mentioned changes. Collectively these results suggest that Calhex₂₃₁ could inhibit Itch-ubiquitin proteasome and TGF-β₁/Smads pathways, and then depress the proliferation of cardiac fibroblasts, along with the reduction deposition of collagen, alleviate glucose-induced myocardial fibrosis. Our findings indicate an important new mechanism for myocardial fibrosis, and suggest Calhex₂₃₁ would be a new therapeutic agent for the treatment of DCM.