Nicotinic Agonist Inhibits Cardiomyocyte Apoptosis in CVB3-Induced Myocarditis via α3β4-nAChR/PI3K/Akt-Dependent Survivin Upregulation

Abstract

Background. Cardiomyocyte apoptosis is critical for the development of coxsackievirus B3- (CVB3-) induced myocarditis, which is a common cardiac disease that may result in heart failure or even sudden death. Previous studies have associated CVB3-induced apoptosis with the downregulation of antiapoptotic proteins. Here, attempts were made to examine whether nicotinic acetylcholine receptors (nAChRs), especially α3β4-nAChRs, were a novel therapeutic antiapoptotic target via the activation of survivin, a strong antiapoptotic protein, in viral myocarditis (VMC). Methods and Results. In the present study, we demonstrated that nAChRs, α3β4-nAChR subunits in particular, were present and upregulated in CVB3-infected neonatal rat cardiomyocytes (NRC) and H9c2 cells by RT-qPCR. The function of α3β4-nAChRs was next examined using its specific blocker α-CTX AuIB in vitro. The results of the TUNEL assay and western blot experiments showed that the block of α3β4-nAChRs abrogated nicotine-mediated protection of NRC from CVB3-induced apoptosis, and this effect displayed a substantial correlation with the protein expressions of pAkt, survivin, and Cleaved Caspase-3. Hence, the involvement of the PI3K/Akt pathway was further verified by LY294002, a selective inhibitor of PI3K. As a result, nicotine-mediated induction of pAkt and survivin was abolished by LY294002; meanwhile, apoptotic NRC were increased accompanied by an increase of Cleaved Caspase-3 expression. Regarding CVB3-infected BALB/c mice, the α-CTX AuIB- and LY294002-treated groups had a lower survival rate, deteriorative ventricular systolic function, and more severe inflammation than the nicotine-treated group and the modulation of pAkt, survivin, and Cleaved Caspase-3 protein expressions was similar to that in CVB3-infected NRC. In addition, we found that a nicotinic agonist reduced CVB3 replication in a dose-dependent manner in vitro, which indicates that nAChR activation may serve as a possible protection mechanism of CVB3-induced myocarditis. Conclusions. Our study demonstrated that α3β4-nAChR subunits are essential in the nicotine-mediated antiapoptotic effect of protecting cardiomyocytes from CVB3-induced apoptosis in vivo and in vitro. This protection correlated with the PI3K/Akt pathway and the inducement of the antiapoptotic protein survivin. A combination of these mechanisms serves as a novel protective response to treat viral myocarditis.

PI3K/AKT pathway as a key link modulates the multidrug resistance of cancers

“…Activated AKT directly phosphorylates Ser136 of Bad (the target of AKT) 42 . AKT activates PAK1, which in turn phosphorylates Bad at Ser-112 and causes its release from the Bcl-xL complex to inhibit apoptosis.…”

STAT3 Suppresses Cardiomyocytes Apoptosis in CVB3-Induced Myocarditis Via Survivin

“…In a study of myocardial ischemia, it was also evident that the expression of survivin protein in cardiomyocytes increased significantly after ischemia-reperfusion injury ( Yang et al, 2015 ). In our previous studies, we noticed that survivin overexpressed in viral myocarditis and the up-regulation of survivin negatively correlated with the expression of Cleaved Caspase-3, suggesting that survivin may protect cardiomyocytes from CVB3- induced apoptosis ( Li et al, 2019 ; Wu et al, 2020 ; Yu et al, 2015 ). Martínez-García et al reported that T21 inhibited STAT3 phosphorylation in lung cancer, which reducing the gene expression of survivin ( Martinez-Garcia et al, 2019 ).…”

<i>BIRC5</i>, <i>GAJ5,</i> and lncRNA NPHP3-AS1 Are Correlated with the Development of Atrial Fibrillation-Valvular Heart Disease

“…39) The up-regulation of survivin plays a vital role in a nicotinic agonist suppressing the apoptosis of cardiomyocyte in CVB3-induced myocarditis. 40) Besides, simvastatin is regarded as being involved in the cardiomyocyte protection and survivin overexpression. 41) These results indicated that survivin is involved in the progression of heart-related diseases.…”