Original Research ARTICLE
Choline attenuates cardiac fibrosis by inhibiting p38MAPK signaling possibly by acting on M3 muscarinic acetylcholine receptor
- 1Second Affiliated Hospital of Harbin Medical University, China
Choline has been reported to produce a variety of cellular functions including cardioprotection via activating M3 muscarinic acetylcholine receptor (M3R) under various insults. However, whether choline offers similar beneficial effects via the same mechanism in cardiac fibrosis remained unexplored. The present study aimed to investigate the effects of choline on cardiac fibrosis and the underlying signalling mechanisms, particularly the possible involvement of M3R. Transverse aortic constriction (TAC) mouse model was established to simulate the cardiac fibrosis. Transforming growth factor (TGF)-β1 treatment was employed to induce proliferation of cardiac fibroblasts in vitro. Choline chloride and M3R antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) were used to unravel the potential role of M3R. Cardiac function was assessed by echocardiography and interstitial fibrosis was quantified by Masson staining. Protein levels of collagens I and III were determined by Western blot analysis. The role of M3R in the proliferation cardiac fibroblasts was validated by silencing M3R with specific siRNA. Furthermore, the MAPK signalling pathway including p38MAPK and ERK1/2 as well as the TGF-β1/Smad pathway were analyzed. M3R protein was found abundantly in cardiac fibroblasts. M3R protein level, as identified by Western blotting, was higher in mice with excessive cardiac fibrosis and in TGF-β1-induced cardiac fibrosis as well. Choline significantly inhibited interstitial fibrosis, and this beneficial action was reversed by 4-DAMP. Production of collagens I and III was reduced after choline treatment but restored by 4-DAMP. Expression silence of endogenous M3R using siRNA increased the level of collagen I. Furthermore, the TGF-β1/Smad2/3 and the p38MAPK pathways were both suppressed by choline. In summary, choline produced an anti-fibrotic effect both in vivo and in vitro by regulating the TGF-β1/Smad2/3 and p38MAPK pathways. These findings unravelled a novel pharmacological property of choline linked to M3R, suggesting that choline regulates cardiac fibrosis and the associated heart diseases possibly by acting on M3R.
Keywords: M3 receptor, cardiac fibrosis, Choline, Collagen, p38MAPK
Received: 10 Jul 2019;
Accepted: 31 Oct 2019.
Copyright: © 2019 Zhao, Chen, Hang, Guo, Li, Pan, Du, Zheng and Du. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Mx. Zhimin Du, Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province, China, email@example.com