A Novel Molecular Mechanism of IKKε-Mediated Akt/mTOR Inhibition in the Cardiomyocyte Autophagy after Myocardial Infarction

SERPINB1 promotes Senecavirus A replication by degrading IKBKE and regulating the IFN pathway via autophagy

IMPORTANCE

Senecavirus A (SVA) is an emerging picornavirus associated with vesicular disease, which wide spreads around the world. It has evolved multiple strategies to evade host immune surveillance. The mechanism and pathogenesis of the virus infection remain unclear. In this study, we show that SERPINB1, a member of the SERPINB family, promotes SVA replication, and regulates both innate immunity and the autophagy pathway. SERPINB1 catalyzes K48-linked polyubiquitination of IκB kinase epsilon (IKBKE) and degrades IKBKE through the proteasome pathway. Inhibition of IKBKE expression by SERPINB1 induces autophagy to decrease type I interferon signaling, and ultimately promotes SVA proliferation. These results provide importantly the theoretical basis of SVA replication and pathogenesis. SERPINB1 could be a potential therapeutic target for the control of viral infection.

Autophagy in Heart Failure: Insights into Mechanisms and Therapeutic Implications

Autophagy, a dynamic and complex process responsible for the clearance of damaged cellular components, plays a crucial role in maintaining myocardial homeostasis. In the context of heart failure, autophagy has been recognized as a response mechanism aimed at counteracting pathogenic processes and promoting cellular health. Its relevance has been underscored not only in various animal models, but also in the human heart. Extensive research efforts have been dedicated to understanding the significance of autophagy and unravelling its complex molecular mechanisms. This review aims to consolidate the current knowledge of the involvement of autophagy during the progression of heart failure. Specifically, we provide a comprehensive overview of published data on the impact of autophagy deregulation achieved by genetic modifications or by pharmacological interventions in ischemic and non-ischemic models of heart failure. Furthermore, we delve into the intricate molecular mechanisms through which autophagy regulates crucial cellular processes within the three predominant cell populations of the heart: cardiomyocytes, cardiac fibroblasts, and endothelial cells. Finally, we emphasize the need for future research to unravel the therapeutic potential associated with targeting autophagy in the management of heart failure.

IKKε protects against starvation-induced NLRP3 inflammasome and pyroptosis in H9c2 cells by alleviating mitochondrial injury

The deprivation of myocardial nutrition causes cardiomyocyte death and disturbance of energy metabolism. IKKε plays an important regulatory role in many biological events such as inflammation, redox reaction, cell death, etc. However, the more in-depth mechanism by which IKKε contributes to cardiomyocytes death in nutrition deprivation remains poorly understood. IKKε expression was knocked down by siRNA in H9c2 cells, and cells were cultured under starvation conditions to simulate ischemic conditions. Starvation triggered greater NLRP3 activation, accompanied by more IL-1β, IL-18 and caspase-1 release in the siIKKε H9c2 cells compared with the control H9c2 cells. Western blot and immunofluorescence showed that the IKKε konckdown promoted NLRP3 expressions and ROS release under starvation conditions. Furthermore, electron micrography and JC-1 analysis revealed that IKKε konckdown resulted in aggravated mitochondrial damage and more mitochondrial ROS (mtROS) released in vitro. Notably, Western blot analysis showed that IKKε deficiency activated the TBK1 and IRF3 signaling pathways to promote pyroptosis in vitro. Collectively, our results indicate that IKKε protects against cardiomyocyte injury by reducing mitochondrial damage and NLRP3 expression following nutrition deprivation via regulation of the TBK1/IRF3 signaling pathway. This study further revealed the mechanism of IKKε in inflammation and myocardial nutrition deprivation.

Nitric Oxide Alleviated High Salt-Induced Cardiomyocyte Apoptosis and Autophagy Independent of Blood Pressure in Rats

The present study aimed to explore whether high-salt diet (HSD) could cause cardiac damage independent of blood pressure, and whether nitric oxide (NO) could alleviate high-salt–induced cardiomyocyte apoptosis and autophagy in rats. The rats received 8% HSD in vivo. H9C2 cells or primary neonatal rat cardiomyocytes (NRCM) were treated with sodium chloride (NaCl) in vitro. The levels of cleaved-caspase 3/caspase 3, cleaved-caspase 8/caspase 8, Bax/Bcl2, LC3 II/LC3 I, Beclin-1 and autophagy related 7 (ATG7) were increased in the heart of HSD rats with hypertension (HTN), and in hypertension-prone (HP) and hypertension-resistant (HR) rats. Middle and high doses (50 and 100 mM) of NaCl increased the level of cleaved-caspase 3/caspase 3, cleaved-caspase 8/caspase 8, Bax/Bcl2, LC3 II/LC3 I, Beclin-1, and ATG7 in H9C2 cells and NRCM. The endothelial NO synthase (eNOS) level was increased, but p-eNOS level was reduced in the heart of HSD rats and H9C2 cells treated with 100 mM NaCl. The level of NO was reduced in the serum and heart of HSD rats. NO donor sodium nitroprusside (SNP) reversed the increases of cleaved-caspase 3/caspase 3, cleaved-caspase 8/caspase 8, Bax/Bcl2 induced by NaCl (100 mM) in H9C2 cells and NRCM. SNP treatment attenuated the increases of cleaved-caspase 3/caspase 3, Bax/Bcl2, LC3 II/LC3 I, Beclin-1, and ATG7 in the heart, but had no effect on the blood pressure of HSD rats with HR. These results demonstrated that HSD enhanced cardiac damage independently of blood pressure. Exogenous NO supplementarity could alleviate the high salt–induced apoptosis and autophagy in cardiomyocytes.