MicroRNA-183-3p up-regulated by vagus nerve stimulation mitigates chronic systolic heart failure via the reduction of BNIP3L-mediated autophagy

Highlights

• miR-183-3p directly targeted BNIP3L in rats.

• miR-183-3p Regulates autophagy via the mTOR/Akt pathway.

Abstract

Chronic systolic heart failure (CSHF) was a complex syndrome. Recently, vagus nerve stimulation (VNS), a novel treatment method, has emerged for the treatment of CSHF. therefore the aim of this study was to explore the possible mechanism of VNS treatment alleviating CSHF in rats. Firstly, we found after VNS treatment for 72 h, the level of B-type natriuretic peptide in VNS group was lower than that in CSHF group. In addition, VNS treatment induced the elevated left ventricular ejection fraction level, reduced left ventricular end diastolic volume and left ventricular end systolic volume level in VNS group, suggesting a mitigation of CSHF by VNS. Then we found the level of miR-183-3p in CSHF group was much lower than that in VNS group by High-throughput sequencing. The further results indicated that Bcl-2 interacting protein 3 like (BNIP3L) was identified as the target gene of miR-183-3p, and the expression of BNIP3L was notably reduced in rats of VNS group compared with CSHF group. Moreover, the down-regulated expression of miR-183-3p increased BNIP3L-mediated autophagy in rats of CSHF group compared with VNS group. Further mechanism findings demonstrated that up-regulation of miR-183-3p reduced the expression of BNIP3L, while down-regulation of miR-183-3p facilitated the expression of BNIP3L in H9c2 cells. miR-183-3p could also regulate autophagy by targeting BNIP3L in vitro, which was manifested by overexpression of miR-183-3p to inhibit BNIP3L-mediated autophagy. Our data demonstrated that VNS treatment benefited CSHF via the up-regulation of miRNA-183-3p, which reduced the BNIP3L-mediated autophagy, providing a new therapeutic direction for CSHF.

Introduction

Chronic systolic heart failure (CSHF), induced by structural or functional heart abnormalities, is a complex syndrome (Murphy and Rosenthal, 2017, Yan et al., 2005). It is characterized by pulmonary and/or systemic blood stasis and insufficient blood perfusion in various organs. Clinical treatment of CSHF aims at delaying heart failure and reducing mortality (Egom, 2015). With the in-depth study of CSHF, besides the traditional diuretic treatment, novel treatment methods such as vagus nerve stimulation (VNS) have emerged (Nicklas et al., 2013, Li et al., 2015). VNS is an innovative therapy with less damage, which has been used to treat drug-resistant epilepsy (Li et al., 2015, Xuan et al., 2017, Nishizaki et al., 2016). The reported mechanisms of VNS in treating CSHF include: reducing heart rate and improving heart rate variability; reducing the aggregation of inflammatory cells; improving NO synthesis and left ventricular function; increasing the expression of connexin 43 (Cx43); as well as reducing cardiomyocyte apoptosis (Sabbah, 2011, Akdemir, 2016, Olshansky, 2016). Knaapen et al. have confirmed that the increasing degree of apoptosis and programmed necrosis of cardiac myocytes in CSHF, accompanied by the up-regulation of autophagy activity (Knaapen et al., 2001). Nevertheless, current studies on the role of autophagy in cardiac diseases have shown inconsistent results. Therefore, it is promising to analyze the relationship between VNS therapy and CSHF from autophagy.

Autophagy refers to the degradation of unnecessary or dysfunctional cytoplasmic organelles or solute components by lysosomes, which is a natural process of cellular internal processing (Linton et al., 2015, Kroemer et al., 2010). Autophagy is essential for maintaining environmental balance in tissues, especially in long-lived cells such as cardiomyocytes (Sun et al., 2018). Recent reports have explored the close relationship between autophagy and cardiac diseases, including myocardial infarction (Legakis et al., 2007), myocardial hypertrophy (Xie and Klionsky, 2007), cardiomyopathy (Ding and Yin, 2012), myocardial fibrosis (Gottlieb and Mentzer, 2013) and heart failure (Badreddin et al., 2018). Excessive autophagy led to cardiac fibrosis and heart failure. Bcl-2 interacting protein 3 like (BNIP3L) locates in mitochondria and directly binds with LC3 to trigger mitochondrial depolarization and mitophagy (Boyd et al., 1994, Lee et al., 2011). In addition, BNIP3L can interact with Bcl-2. Bcl-2 is also important negative regulators of autophagy through an inhibitory interaction of Beclin 1, which mediates autophagic initiation (Matsushima et al., 1998, Zhang and Ney, 2011, Wu et al., 2015).

MicroRNA (miRNA) is a highly conserved, endogenous, single-stranded, non-coding small RNA molecule (Treiber et al., 2018). miRNA inhibits target gene expression by directly binding to its mRNAs. Over the past decade, numerous studies have stated the molecular details of miRNA function and biogenesis (Cao et al., 2000). It has been identified that aberrant miRNA expression was associated with many diseases, such as cancer and CSHF (Allida et al., 2015, Spinarova and Vitovec, 2007). The mimic and inhibitor of miRNA has been developed for the treatment of these diseases. Therefore, the purpose of this study was to explore whether VNS alleviates CSHF by the regulation of miRNA level and autophagy, and investigate the molecular regulation mechanisms.