C1q/tumor necrosis factor-related protein-6 suppresses the angiotensin II-induced differentiation of cardiac fibroblasts to myofibroblasts via activation of the AMPK pathway

C1q/tumor necrosis factor-related protein-6 (CTRP6) has multiple protective effects against cardiovascular diseases. Myofibroblast differentiation plays a critical role in cardiac fibrosis under various cardiac pathological conditions. The aim of the present study was to determine the effects of CTRP6 on cardiac fibrosis, and to identify the possible mechanisms of action. Toward this end, we measured the expression of fibrotic markers, including collagen I, collagen III, CTGF, and TGFβ1, and assessed the effects of CTRP6 on cardiac fibroblast differentiation into myofibroblasts. CTRP6 inhibited the expression of the angiotensin II (Ang II)-induced myofibroblast markers α-SMA and SM22, and of profibrotic molecules, including collagen I, collagen III, CTGF, TGFβ1, MMP2, MMP9, and TIMP1. Furthermore, CTRP6 significantly attenuated the proliferation and migration of cardiac fibroblasts incubated with Ang II and activated the phosphorylation of AMP-activated protein kinase (AMPK). Incubation with an AMPK inhibitor reversed the subsequent inhibitory effects of CTRP6 on Ang II-induced myofibroblast differentiation. Therefore, CTRP6 suppresses cardiac fibrosis by inhibition of myofibroblast differentiation via AMPK pathway activation, suggesting CTRP6 as a target for the treatment of cardiac fibrosis.