Hydrogen sulfide pretreatment improves mitochondrial function in myocardial hypertrophy via a SIRT3-dependent manner

Hydrogen sulfide mitigates mitochondrial dysfunction and cellular senescence in diabetic patients: Potential therapeutic applications

Diabetes induces a pro-aging state characterized by an increased abundance of senescent cells in various tissues, heightened chronic inflammation, reduced substance and energy metabolism, and a significant increase in intracellular reactive oxygen species (ROS) levels. This condition leads to mitochondrial dysfunction, including elevated oxidative stress, the accumulation of mitochondrial DNA (mtDNA) damage, mitophagy defects, dysregulation of mitochondrial dynamics, and abnormal energy metabolism. These dysfunctions result in intracellular calcium ion (Ca2+) homeostasis disorders, telomere shortening, immune cell damage, and exacerbated inflammation, accelerating the aging of diabetic cells or tissues. Hydrogen sulfide (H2S), a novel gaseous signaling molecule, plays a crucial role in maintaining mitochondrial function and mitigating the aging process in diabetic cells. This article systematically explores the specific mechanisms by which H2S regulates diabetes-induced mitochondrial dysfunction to delay cellular senescence, offering a promising new strategy for improving diabetes and its complications.

The functional role of m6A demethylase ALKBH5 in cardiomyocyte hypertrophy

Cardiomyocyte hypertrophy is a major outcome of pathological cardiac hypertrophy. The m6A demethylase ALKBH5 is reported to be associated with cardiovascular diseases, whereas the functional role of ALKBH5 in cardiomyocyte hypertrophy remains confused. We engineered Alkbh5 siRNA (siAlkbh5) and Alkbh5 overexpressing plasmid (Alkbh5 OE) to transfect cardiomyocytes. Subsequently, RNA immunoprecipitation (RIP)-qPCR, MeRIP-qPCR analysis and the dual-luciferase reporter assays were applied to elucidate the regulatory mechanism of ALKBH5 on cardiomyocyte hypertrophy. Our study identified ALKBH5 as a new contributor of cardiomyocyte hypertrophy. ALKBH5 showed upregulation in both phenylephrine (PE)-induced cardiomyocyte hypertrophic responses in vitro and transverse aortic constriction (TAC)/high fat diet (HFD)-induced pathological cardiac hypertrophy in vivo. Knockdown or overexpression of ALKBH5 regulated the occurrence of hypertrophic responses, including the increased cardiomyocyte surface areas and elevation of the hypertrophic marker levels, such as brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP). Mechanically, we indicated that ALKBH5 activated JAK2/STAT3 signaling pathway and mediated m6A demethylation on Stat3 mRNA, but not Jak2 mRNA, resulting in the phosphorylation and nuclear translocation of STAT3, which enhances the transcription of hypertrophic genes (e.g., Nppa) and ultimately leads to the emergence of cardiomyocytes hypertrophic growth. Our work highlights the functional role of ALKBH5 in regulating the onset of cardiomyocyte hypertrophy and provides a potential target for hypertrophic heart diseases prevention and treatment. ALKBH5 activated JAK2/STAT3 signaling pathway and mediated m6A demethylation on Stat3 mRNA, but not Jak2 mRNA, resulting in the phosphorylation and nuclear translocation of STAT3, which enhances the transcription of hypertrophic genes (e.g., Nppa) and ultimately leads to the emergence of cardiomyocytes hypertrophic growth.

Hydrogen sulfide supplementation as a potential treatment for primary mitochondrial diseases

Primary mitochondrial diseases (PMD) are amongst the most common inborn errors of metabolism causing fatal outcomes within the first decade of life. With marked heterogeneity in both inheritance patterns and physiological manifestations, these conditions present distinct challenges for targeted drug therapy, where effective therapeutic countermeasures remain elusive within the clinic. Hydrogen sulfide (H2S)-based therapeutics may offer a new option for patient treatment, having been proposed as a conserved mitochondrial substrate and post-translational regulator across species, displaying therapeutic effects in age-related mitochondrial dysfunction and neurodegenerative models of mitochondrial disease. H2S can stimulate mitochondrial respiration at sites downstream of common PMD-defective subunits, augmenting energy production, mitochondrial function and reducing cell death. Here, we highlight the primary signalling mechanisms of H2S in mitochondria relevant for PMD and outline key cytoprotective proteins/pathways amenable to post-translational restoration via H2S-mediated persulfidation. The mechanisms proposed here, combined with the advent of potent mitochondria-targeted sulfide delivery molecules, could provide a framework for H2S as a countermeasure for PMD disease progression.

Breviscapine protects against pathological cardiac hypertrophy by targeting FOXO3a-mitofusin-1 mediated mitochondrial fusion

Forkhead box O3a (FOXO3a)-mediated mitochondrial dysfunction plays a pivotal effect on cardiac hypertrophy and heart failure (HF). However, the role and underlying mechanisms of FOXO3a, regulated by breviscapine (BRE), on mitochondrial function in HF therapy remain unclear. This study reveals that BRE-induced nuclear translocation of FOXO3a facilitates mitofusin-1 (MFN-1)-dependent mitochondrial fusion in cardiac hypertrophy and HF. BRE effectively promotes cardiac function and ameliorates cardiac remodeling in pressure overload-induced mice. In addition, BRE mitigates phenylephrine (PE)-induced cardiac hypertrophy in cardiomyocytes and fibrosis remodeling in fibroblasts by inhibiting ROS production and promoting mitochondrial fusion, respectively. Transcriptomics analysis underscores the close association between the FOXO pathway and the protective effect of BRE against HF, with FOXO3a emerging as a potential target of BRE. BRE potentiates the nuclear translocation of FOXO3a by attenuating its phosphorylation, other than its acetylation in cardiac hypertrophy. Mechanistically, over-expression of FOXO3a significantly inhibits cardiac hypertrophy and mitochondrial injury by promoting MFN-1-mediated mitochondrial fusion. Furthermore, BRE demonstrates its ability to substantially curb cardiac hypertrophy, reduce mitochondrial ROS production, and enhance MFN-1-mediated mitochondrial fusion through a FOXO3a-dependent mechanism. In conclusion, nuclear FOXO3a translocation induced by BRE presents a successful therapeutic avenue for addressing cardiac hypertrophy and HF through promoting MFN-1-dependent mitochondrial fusion.

SIRT3 regulates mitochondrial function: A promising star target for cardiovascular disease therapy

Dysregulation of mitochondrial homeostasis is common to all types of cardiovascular diseases. SIRT3 regulates apoptosis and autophagy, material and energy metabolism, mitochondrial oxidative stress, inflammation, and fibrosis. As an important mediator and node in the network of mechanisms, SIRT3 is essential to many activities. This review explains how SIRT3 regulates mitochondrial homeostasis and the tricarboxylic acid cycle to treat common cardiovascular diseases. A novel description of the impact of lifestyle factors on SIRT3 expression from the angles of nutrition, exercise, and temperature is provided.

Cytoplasmic Escape of Mitochondrial DNA Mediated by Mfn2 Downregulation Promotes Microglial Activation via cGas-Sting Axis in Spinal Cord Injury

Neuroinflammation is associated with poor outcomes in patients with spinal cord injury (SCI). Recent studies have demonstrated that stimulator of interferon genes (Sting) plays a key role in inflammatory diseases. However, the role of Sting in SCI remains unclear. In the present study, it is found that increased Sting expression is mainly derived from activated microglia after SCI. Interestingly, knockout of Sting in microglia can improve the recovery of neurological function after SCI. Microglial Sting knockout restrains the polarization of microglia toward the M1 phenotype and alleviates neuronal death. Furthermore, it is found that the downregulation of mitofusin 2 (Mfn2) expression in microglial cells leads to an imbalance in mitochondrial fusion and division, inducing the release of mitochondrial DNA (mtDNA), which mediates the activation of the cGas-Sting signaling pathway and aggravates inflammatory response damage after SCI. A biomimetic microglial nanoparticle strategy to deliver MASM7 (named MSNs-MASM7@MI) is established. In vitro, MSNs-MASM7@MI showed no biological toxicity and effectively delivered MASM7. In vivo, MSNs-MASM7@MI improves nerve function after SCI. The study provides evidence that cGas-Sting signaling senses Mfn2-dependent mtDNA release and that its activation may play a key role in SCI. These findings provide new perspectives and potential therapeutic targets for SCI treatment.

A review for the correlation between optic atrophy 1-dependent mitochondrial fusion and cardiovascular disorders

Mitochondrial dynamics homeostasis is sustained by continuous and balanced fission and fusion, which are determinants of morphology, abundance, biogenesis and mitophagy of mitochondria. Optic atrophy 1 (OPA1), as the only inner mitochondrial membrane fusion protein, plays a key role in stabilizing mitochondrial dynamics. The disturbance of mitochondrial dynamics contributes to the pathophysiological progress of cardiovascular disorders, which are the main cause of death worldwide in recent decades and result in tremendous social burden. In this review, we describe the latest findings regarding OPA1 and its role in mitochondrial fusion. We summarize the post-translational modifications (PTMs) for OPA1 and its regulatory role in mitochondrial dynamics. Then the diverse cell fates caused by OPA1 expression during cardiovascular disorders are discussed. Moreover, cardiovascular disorders (such as heart failure, myocardial ischemia/reperfusion injury, cardiomyopathy and cardiac hypertrophy) relevant to OPA1-dependent mitochondrial dynamics imbalance have been detailed. Finally, we highlight the potential that targeting OPA1 to impact mitochondrial fusion may be used as a novel strategy against cardiovascular disorders.

Exogenous NADPH exerts a positive inotropic effect and enhances energy metabolism via SIRT3 in pathological cardiac hypertrophy and heart failure

BACKGROUND

Therapies are urgently required to ameliorate pathological cardiac hypertrophy and enhance cardiac function in heart failure. Our preliminary experiments have demonstrated that exogenous NADPH exhibits a positive inotropic effect on isolated heart. This study aims to investigate the positive inotropic effects of NADPH in pathological cardiac hypertrophy and heart failure, as well as the underlying mechanisms involved.

METHODS

Endogenous plasma NADPH contents were determined in patients with chronic heart failure and control adults. The positive inotropic effects of NADPH were investigated in isolated toad heart or rat heart. The effects of NADPH were investigated in isoproterenol (ISO)-induced cardiac hypertrophy or transverse aortic constriction (TAC)-induced heart failure. The underlying mechanisms of NADPH were studied using SIRT3 knockout mice, echocardiography, Western blotting, transmission electron microscopy, and immunoprecipitation.

FINDINGS

The endogenous NADPH content in the blood of patients and animals with pathological cardiac hypertrophy or heart failure was significantly reduced compared with age-sex matched control subjects. Exogenous NADPH showed positive inotropic effects on the isolated normal and failing hearts, while antagonism of ATP receptor partially abolished the positive inotropic effect of NADPH. Exogenous NADPH administration significantly reduced heart weight indices, and improved cardiac function in the mice with pathological cardiac hypertrophy or heart failure. NADPH increased SIRT3 expression and activity, deacetylated target proteins, improved mitochondrial function and facilitated ATP production in the hypertrophic myocardium. Importantly, inhibition of SIRT3 abolished the positive inotropic effect of NADPH, and the anti-heart failure effect of NADPH was significantly reduced in the SIRT3 Knockout mice.

INTERPRETATION

Exogenous NADPH shows positive inotropic effect and improves energy metabolism via SIRT3 in pathological cardiac hypertrophy and heart failure. NADPH thus may be one of the potential candidates for the treatment of pathological cardiac hypertrophy or heart failure.

FUNDING

This work was supported by grants from the National Natural Science Foundation of China (No. 81973315, 82173811, 81730092), Natural Science Foundation of Jiangsu Higher Education (20KJA310008), Jiangsu Key Laboratory of Neuropsychiatric Diseases (BM2013003) and the Priority Academic Program Development of the Jiangsu Higher Education Institutes (PAPD).

Human Fis1 directly interacts with Drp1 in an evolutionarily conserved manner to promote mitochondrial fission

Mitochondrial fission protein 1 (Fis1) and dynamin-related protein 1 (Drp1) are the only two proteins evolutionarily conserved for mitochondrial fission, and directly interact in Saccharomyces cerevisiae to facilitate membrane scission. However, it remains unclear if a direct interaction is conserved in higher eukaryotes as other Drp1 recruiters, not present in yeast, are known. Using NMR, differential scanning fluorimetry, and microscale thermophoresis, we determined that human Fis1 directly interacts with human Drp1 (KD = 12-68 μM), and appears to prevent Drp1 assembly, but not GTP hydrolysis. Similar to yeast, the Fis1-Drp1 interaction appears governed by two structural features of Fis1: its N-terminal arm and a conserved surface. Alanine scanning mutagenesis of the arm identified both loss-of-function and gain-of-function alleles with mitochondrial morphologies ranging from highly elongated (N6A) to highly fragmented (E7A), demonstrating a profound ability of Fis1 to govern morphology in human cells. An integrated analysis identified a conserved Fis1 residue, Y76, that upon substitution to alanine, but not phenylalanine, also caused highly fragmented mitochondria. The similar phenotypic effects of the E7A and Y76A substitutions, along with NMR data, support that intramolecular interactions occur between the arm and a conserved surface on Fis1 to promote Drp1-mediated fission as in S. cerevisiae. These findings indicate that some aspects of Drp1-mediated fission in humans derive from direct Fis1-Drp1 interactions that are conserved across eukaryotes.

SOX4 as a potential therapeutic target for pathological cardiac hypertrophy

Pathological cardiac hypertrophy can lead to heart failure, making its prevention crucial. SOX4, a SOX transcription factor, regulates tissue growth and development, although its role in pathological cardiac hypertrophy is unclear. We found that the SOX4 expression was elevated in hypertrophic hearts and angiotensin II (Ang II)-treated neonatal rat cardiomyocytes (NRCMs), and knocking down the SOX4 expression in NRCMs and mouse hearts significantly reduced the hypertrophic response. Mechanistically, SOX4 can bind to the SIRT3 promoter, inhibit SIRT3 transcription and expression, and thus affect downstream MnSOD acetylation levels, leading to abnormal increases in ROS and oxidative stress levels and promoting the occurrence of cardiac hypertrophy. In conclusion, this study identified a new role for SOX4 in regulating cardiac hypertrophy, and decreasing SOX4 expression may be a potential treatment for pathological cardiac hypertrophy.

Cyclovirobuxine D alleviates aldosterone-induced myocardial hypertrophy by protecting mitochondrial function depending on the mutual regulation of Nrf2-SIRT3

BACKGROUND

Cyclovirobuxine D (CVB-D) is a natural alkaloid that exhibits multiple pharmacological activities, such as anti-inflammatory, anti-oxidative stress, and anti-cancer properties. However, its specific protective mechanism of action for myocardial hypertrophy remains unresolved.

PURPOSE

This work was to investigate the ameliorative impact of CVB-D in myocardial hypertrophy, and to elucidate aldosterone (ALD)-induced myocardial hypertrophy by inhibiting the SIRT3 mediated Nrf2 activation.

METHODS

The myocardial hypertrophy model was reproduced by ALD both in vitro and in vivo, and the protective effect of CVB-D on myocardium and mitochondria was evaluated by TEM, H&E, qPCR, Western blot and ChIP. An immunoprecipitation experiment was adopted to evaluate the acetylation level of Nrf2 and the binding between SIRT3 and Nrf2. Additionally, bardoxolone-methyl (BAR, an Nrf2 agonist), ML385 (an Nrf2 inhibitor), resveratrol (RES, a SIRT3 agonist), and 3-TYP (a SIRT3 inhibitor) were used to confirm the molecular mechanism of CVB-D. Lastly, a molecular docking technique was employed to predict the binding site of SIRT3 and Nrf2 proteins.

RESULTS

Our findings suggested that CVB-D improved mitochondrial function, leading to a reduction in ALD-induced cardiomyocyte hypertrophy. By CVB-D treatment, there was an activation of mutual regulation between Nrf2 and SIRT3. Specifically, CVB-D resulted in the increase of Nrf2 protein in the nucleus and activated Nrf2 signaling pathway, thus up-regulating SIRT3. The activation of SIRT3 and the protective action of mitochondrion disappeared because of the intervention of ML385. After CVB-D activated SIRT3, the acetylation level of Nrf2 decreased, followed by activating the Nrf2 pathway. The activation of Nrf2 and mitochondrial protection by CVB-D were reversed by 3-TYP. Our results are also supported by Co-IP and molecular docking analysis, revealing that CVB-D promotes SIRT3-mediated Nrf2 activation.

CONCLUSION

Thus, CVB-D ameliorates ALD-induced myocardial hypertrophy by recovering mitochondrial function by activating the mutual regulation of Nrf2 and SIRT3. Thus, CVB-D could be a beneficial drug for myocardial hypertrophy.

The Regulatory Effect of Receptor-Interacting Protein Kinase 3 on CaMKIIδ in TAC-Induced Myocardial Hypertrophy

Necroptosis is a newly discovered mechanism of cell death, and its key regulatory role is attributed to the interaction of receptor-interacting protein kinases (RIPKs) RIPK1 and RIPK3. Ca2+/calmodulin-dependent protein kinase (CaMKII) is a newly discovered RIPK3 substrate, and its alternative splicing plays a fundamental role in cardiovascular diseases. In the present study, we aimed to explore the role and mechanism of necroptosis and alternative splicing of CaMKIIδ in myocardial hypertrophy. Transverse aortic constriction (TAC) was performed on wild-type and knockout mice to establish the model of myocardial hypertrophy. After 3 weeks, echocardiography, cardiac index, cross-sectional area of myocardial cells, hypertrophic gene expression, myocardial damage, and fibers were assessed. Moreover, we detected the levels of inflammatory factors (IL-6 and TNF-α) and examined the expressions of necroptosis-related proteins RIPK3, RIPK1, and phosphorylated MLKL. Meanwhile, we tested the expression levels of splicing factors ASF/SF2 and SC-35 in an attempt to explore CaMKII δ. The relationship between variable splicing disorder and the expression levels of splicing factors ASF/SF2 and SC-35. Further, we also investigated CaMKII activation, oxidative stress, and mitochondrial ultrastructure. In addition, wild-type mice were administered with a recombinant adeno-associated virus (AAV) carrying RIPK3, followed by TAC surgery to construct a model of myocardial hypertrophy, and the above-mentioned indicators were tested after 3 weeks. The results showed that RIPK3 deficiency could alleviate cardiac dysfunction, myocardial injury, aggravation of necrosis, and CaMKII activation induced by TAC surgery in mice with myocardial hypertrophy. Tail vein injection of AAV could reverse cardiac dysfunction, myocardial damage, aggravation of necrosis, and CaMKII activation in mice with myocardial hypertrophy. These results proved that RIPK3 could be used as a molecular intervention target for the prevention and treatment of myocardial hypertrophy.

Hydrogen sulfide promoted retinoic acid-related orphan receptor α transcription to alleviate diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is one serious and common complication in diabetes without effective treatments. Hydrogen sulfide (H2S) fights against a variety of cardiovascular diseases including DCM. Retinoic acid-related orphan receptor α (RORα) has protective effects on cardiovascular system. However, whether RORα mediates the protective effect of H2S against DCM remains unknown. The present research was to explore the roles and mechanisms of RORα in H2S against DCM. The study demonstrated that H2S donor sodium hydrosulfide (NaHS) alleviated cell injury but enhanced RORα expression in high glucose (HG)-stimulated cardiomyocytes. However, NaHS no longer had the protective effect on attenuating cell damage and oxidative stress, improving mitochondrial membrane potential, inhibiting necroptosis and enhanced signal transducer and activator of transcription 3 (STAT3) Ser727 phosphorylation in HG-stimulated cardiomyocytes after RORα siRNA transfection. Moreover, NaHS improved cardiac function, attenuated myocardial hypertrophy and fibrosis, alleviated oxidative stress, inhibited necroptosis, but increased STAT3 phosphorylation in wild type (WT) mice but not in RORα knockout mice (a spontaneous staggerer mice, sg/sg mice) with diabetes. Additionally, NaHS increased RORα promoter activity in cardiomyocytes with HG stimulation, which was related to the binding sites of E2F transcription factor 1 (E2F1) in the upstream region of RORα promoter. NaHS enhanced E2F1 expression and increased the binding of E2F1 to RORα promoter in cardiomyocytes with HG stimulation. In sum, H2S promoted RORα transcription via E2F1 to alleviate necroptosis and protect against DCM. It is helpful to propose a novel therapeutic implication for DCM.

The potential role of alfalfa polysaccharides and their sulphated derivatives in the alleviation of obesity

Sulfated alfalfa polysaccharides (SAPs) as derivatives of alfalfa polysaccharides (APs) showed better in vitro antioxidant activity and potential obesity inhibition. The purpose of this study was to investigate the effect and mechanisms of APs and SAPs on obesity alleviation. Different concentrations of APs and SAPs were tested for effects on body conditions, gut flora, antioxidant capacity, and immunological factors. The results showed that APs and SAPs improved the physical conditions of obese mice, including organ weight, body weight, intraperitoneal fat ratio, and lipid levels. APs and SAPs increased the antioxidant capacity of the obese mice, enhanced the activity of SOD and CAT, and decreased the activity of MDA in the serum, liver, and colon. APs and SAPs upregulated the mRNA expression of IL-4 and IL-10 and downregulated the mRNA expression of NF-κB, IFN-γ, TNF-α, and IL-6 in the liver and colon. Meanwhile, APs and SAPs improved lipid absorption in the jejunum, upregulated LXR and GLP-2, and down-regulated the mRNA expression of NPC1L1. APs and SAPs also contributed to restoring short-chain fatty acid levels in the colon. APs and SAPs improved the structure of the intestinal flora, promoted the proliferation of bacteria associated with short-chain fatty acid metabolism, and inhibited the proliferation of pathogenic bacteria. At the same concentration, the effect of SAPs on the antioxidant capacity was stronger than that of APs. In the AP group, high concentrations of APs showed the best anti-inflammatory effect, while in the SAP group, medium concentrations of SAPs showed the best inhibition of inflammation. Our results suggest that APs and SAPs alleviate obesity symptoms by relieving inflammation, improving the antioxidant capacity, and regulating intestinal flora and therefore could be used as potential probiotic products to alleviate obesity.

Human Fis1 directly interacts with Drp1 in an evolutionarily conserved manner to promote mitochondrial fission

Mitochondrial Fission Protein 1 (Fis1) and Dynamin Related Protein 1 (Drp1) are the only two proteins evolutionarily conserved for mitochondrial fission, and directly interact in S. cerevisiae to facilitate membrane scission. However, it remains unclear if a direct interaction is conserved in higher eukaryotes as other Drp1 recruiters, not present in yeast, are known. Using NMR, differential scanning fluorimetry, and microscale thermophoresis, we determined that human Fis1 directly interacts with human Drp1 ( K D = 12-68 µM), and appears to prevent Drp1 assembly, but not GTP hydrolysis. Similar to yeast, the Fis1-Drp1 interaction appears governed by two structural features of Fis1: its N-terminal arm and a conserved surface. Alanine scanning mutagenesis of the arm identified both loss- and gain-of-function alleles with mitochondrial morphologies ranging from highly elongated (N6A) to highly fragmented (E7A) demonstrating a profound ability of Fis1 to govern morphology in human cells. An integrated analysis identified a conserved Fis1 residue, Y76, that upon substitution to alanine, but not phenylalanine, also caused highly fragmented mitochondria. The similar phenotypic effects of the E7A and Y76A substitutions, along with NMR data, support that intramolecular interactions occur between the arm and a conserved surface on Fis1 to promote Drp1-mediated fission as in S. cerevisiae . These findings indicate that some aspects of Drp1-mediated fission in humans derive from direct Fis1-Drp1 interactions that are conserved across eukaryotes.

Dihydromyricetin Attenuates Diabetic Cardiomyopathy by Inhibiting Oxidative Stress, Inflammation and Necroptosis via Sirtuin 3 Activation

Dihydromyricetin (DHY), the main flavonoid component in Ampelopsis grossedentata, has important benefits for health. The present study aimed to investigate the exact effects and possible mechanisms of DHY on diabetic cardiomyopathy (DCM). Male C57BL/6 mice and sirtuin 3 (SIRT3) knockout (SIRT3-KO) mice were injected with streptozotocin (STZ) to induce a diabetic model. Two weeks later, DHY (250 mg/kg) or carboxymethylcellulose (CMC) were administrated once daily by gavage for twelve weeks. We found that DHY alleviated fasting blood glucose (FBG) and triglyceride (TG) as well as glycosylated hemoglobin (HbA1c) levels; increased fasting insulin (FINS); improved cardiac dysfunction; ameliorated myocardial hypertrophy, fibrosis and injury; suppressed oxidative stress, inflammasome and necroptosis; but improved SIRT3 expression in STZ-induced mice. Neonatal rat cardiomyocytes were pre-treated with DHY (80 μM) with or without high glucose (HG) stimulation. The results showed that DHY attenuated cell damage but improved SIRT3 expression and inhibited oxidative stress, inflammasome and necroptosis in cardiomyocytes with high glucose stimulation. Moreover, the above protective effects of DHY on DCM were unavailable in SIRT3-KO mice, implying a promising medical potential of DHY for DCM treatment. In sum, DHY improved cardiac dysfunction; ameliorated myocardial hypertrophy, fibrosis and injury; and suppressed oxidative stress, inflammation and necroptosis via SIRT3 activation in STZ-induced diabetic mice, suggesting DHY may serve as a candidate for an agent to attenuate diabetic cardiomyopathy.

Berberine Ameliorates Abnormal Lipid Metabolism via the Adenosine Monophosphate-Activated Protein Kinase/Sirtuin 1 Pathway in Alcohol-Related Liver Disease

Alcoholic fatty liver disease (AFLD) is an early stage of alcohol-related liver disease characterized by abnormal lipid metabolism in hepatocytes. To date, to our knowledge, there have been no effective strategies for preventing or treating alcohol-related liver disease besides alcohol abstinence. Berberine (BBR) is the main bioactive ingredient extracted from traditional Chinese medicines, such as Coptis and Scutellaria, which protect liver function and relieve liver steatosis. However, the potential role of BBR in AFLD remains unclear. Therefore, this study investigated the protective effects of BBR against Gao-binge model-induced AFLD in 6- to 8-week-old C57BL/6J male mice in vivo and ethyl alcohol (EtOH)-induced alpha mouse liver 12 (AML-12) cells in vitro. The results showed that BBR (200 mg/kg) attenuated alcoholic liver injury and suppressed lipid accumulation and metabolism disorders in vivo. Consistently, BBR effectively inhibited the expression of sterol regulatory element-binding transcription factor 1C, sterol regulatory element-binding transcription factor 2, fatty acid synthase, and 3-hydroxy-3-methylglutaryl-CoenzymeA reductase in EtOH-stimulated AML-12 cells in vitro and promoted the expression of sirtuin 1 (SIRT1) in EtOH-fed mice and EtOH-treated AML-12 cells. Furthermore, SIRT1 silencing attenuated the hepatic steatosis alleviation potential of BBR treatment. Mechanistically, molecular docking revealed the binding effect of BBR and adenosine monophosphate-activated protein kinase (AMPK). The results of further studies showed that a decrease in AMPK activity was accompanied by a significant inhibition of SIRT1 expression. SIRT1 silencing attenuated the protective effect of BBR, whereas the inhibition of its expression had no apparent effect on AMPK phosphorylation, suggesting that SIRT1 acts downstream of AMPK in AFLD. Collectively, BBR ameliorated abnormal lipid metabolism and alleviated EtOH-induced liver injury via the AMPK/SIRT1 pathway in AFLD mice.

Extracellular vesicles DJ-1 derived from hypoxia-conditioned hMSCs alleviate cardiac hypertrophy by suppressing mitochondria dysfunction and preventing ATRAP degradation

BACKGROUND

As a pathological myocardial remodeling process in a variety of cardiovascular diseases, cardiac hypertrophy still has no effective treatment. Human mesenchymal stem cells (hMSCs) derived extracellular vesicles (EVs) has been recognized as a promising treatment strategy for cardiac disease.

METHODS

In this study, the inhibitory effects on cardiac hypertrophy are compared between normoxia-conditioned hMSC-derived EVs (Nor-EVs) and hypoxia-conditioned hMSC-derived EVs (Hypo-EVs) in neonatal rat cardiomyocytes (NRCMs) after angiotensin II (Ang II) stimulation and in a mouse model of transverse aortic constriction (TAC).

RESULTS

We demonstrate that Hypo-EVs exert an increased inhibitory effect on cardiac hypertrophy compared with Nor-EVs. Parkinson disease protein 7 (PARK7/DJ-1) is identify as a differential protein between Nor-EVs and Hypo-EVs by quantitative proteomics analysis. Results show that DJ-1, which is rich in Hypo-EVs, alleviates mitochondrial dysfunction and excessive mitochondrial reactive oxygen species (mtROS) production as an antioxidant. Mechanistic studies demonstrate for the first time that DJ-1 may suppress cardiac hypertrophy by inhibiting the activity of proteasome subunit beta type 10 (PSMB10) through a direct physical interaction. This interaction can inhibit angiotensin II type 1 receptor (AT1R)-mediated signaling pathways resulting in cardiac hypertrophy through alleviating ubiquitination degradation of AT1R-associated protein (ATRAP).

CONCLUSIONS

When taken together, our study suggests that Hypo-EVs have significant potential as a novel therapeutic agent for the treatment of cardiac hypertrophy.

Lysine demethylase KDM5B down-regulates SIRT3-mediated mitochondrial glucose and lipid metabolism in diabetic neuropathy

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a common neurological complication of diabetes mellitus without efficient interventions. Both lysine demethylase 5B (KDM5B) and sirtuin-3 (SIRT3) have been found to regulate islet function and glucose homeostasis. KDM5B was predicted to bind to the SIRT3 promoter by bioinformatics. Here, we investigated whether KDM5B affected DPN development via modulating SIRT3.

METHODS

The db/db mice and high glucose-stimulated Schwann cells (RSC96) were used as in vivo and in vitro models of DPN, respectively. Glucose level, glucose and insulin tolerance of mice were measured. Neurological function was evaluated by motor nerve conduction velocity (MNCV), tactile allodynia assay and thermal sensitivity assay. Adenosine triphosphate level, oxygen consumption rate, extracellular acidification rate, β-oxidation rate, acetyl-CoA level, acetylation levels and activities of long-chain acyl CoA dehydrogenase (LCAD) and pyruvate dehydrogenase (PDH) were detected. Methyl thiazolyl tetrazolium assay was adopted to determine cell viability. Reactive oxygen species (ROS) production was detected by MitoSox staining. Western blotting for measuring target protein levels. Molecular mechanisms were investigated by co-immunoprecipitine (Co-IP), chromatin immunoprecipitation (ChIP) and luciferase reporter assay.

RESULTS

KDM5B was up-regulated, while SIRT3 was down-regulated in DPN models. SIRT3 overexpression or AMPK activation ameliorated mitochondrial metabolism dysfunction and ROS overproduction during DPN. KDM5B overexpression triggered mitochondrial metabolism disorder and oxidative stress via directly transcriptional inhibiting SIRT3 expression by demethylating H3K4me3 or indirectly repressing AMPK pathway-regulated SIRT3 expression.

CONCLUSION

KDM5B contributes to DPN via regulating SIRT3-mediated mitochondrial glucose and lipid metabolism. KDM5B inhibition may be an effective intervention for DPN.

Polysulfide Protects Against Diabetic Cardiomyopathy Through Sulfhydration of Peroxisome Proliferator-Activated Receptor-γ and Sirtuin 3

Aims: Diabetic cardiomyopathy (DCM) is characterized by cardiac dysfunction and heart failure. However, the effective therapy for DCM is still lacking. Polysulfide contains chains of sulfur atoms, and accumulative evidence has shown that it actively participates in mammalian physiology or pathophysiology. Nevertheless, the potential effects and mechanisms of polysulfide in DCM need further investigation. In the present study, Na₂S₄, a polysulfide donor, was employed to investigate the therapeutic effects of polysulfide in DCM. Results: Our results showed that Na₂S₄ protected cardiomyocytes against high glucose (HG)-induced cardiomyocyte injury. The pathological changes in DCM including cell death, oxidative stress, mitochondrial dysfunction and cardiac hypertrophy were improved by Na₂S₄ treatment. The left ventricular contractile function in streptozotocin (STZ)-induced diabetic mice was significantly improved by Na₂S₄. Mechanistically, Na₂S₄ upregulated and sulfhydrated peroxisome proliferator-activated receptor-γ (PPARγ) and sirtuin 3 (SIRT-3) in cardiomyocytes. Suppression of PPARγ or SIRT-3 with their specific inhibitors or blockade of sulfhydration abolished the protective effects of Na₂S₄. Moreover, mutations of PPARγ or SIRT-3 at specific cysteines diminished the benefits of Na₂S₄ in HG-challenged cardiomyocytes. Innovation and Conclusion: We demonstrated that Na₂S₄ prevented the development of DCM via sulfhydration of both PPARγ and SIRT-3. Our results imply that polysulfide may be a potential and promising agent to treat DCM. Antioxid. Redox Signal. 38, 1-17.

A novel mechanism for the protection against acute lung injury by melatonin: mitochondrial quality control of lung epithelial cells is preserved through SIRT3-dependent deacetylation of SOD2

The mitochondrial quality control of lung epithelial cells is disturbed during sepsis, which contributes to abnormal mitochondrial function and acute lung injury. Melatonin is one of the primary hormones secreted by the pineal gland, displaying favorable antioxidative actions in sepsis and cardiopulmonary disease. However, the potential roles and molecular basis of melatonin in lipopolysaccharide (LPS)-treated lung epithelial cells have not been explored and reported. Herein, we investigated whether melatonin could protect against sepsis-induced acute lung injury (ALI) and LPS-treated lung epithelial cells through the mitochondrial quality control as well as its possible molecular targets. Wild type and Sirt3 knockout mice were intratracheally instilled with LPS for 12 h to construct an in vivo acute lung injury model. Both A549 lung epithelial cells and primary alveolar type II (AT-II) cells were used to explore the possible roles of melatonin in vitro by incubating with small interfering RNA against Sirt3. To determine the involvement of the melatonin receptor, cells and mice were treated with si Mtnr1b and luzindole. Melatonin pretreatment significantly inhibited pathological injury, inflammatory response, oxidative stress, and apoptosis in LPS-treated lung tissues and LPS-treated lung epithelial cells. Furthermore, melatonin also shifted the dynamic course of mitochondria from fission to fusion, inhibited mitophagy and fatty acid oxidation in LPS-treated lung epithelial cells in vitro and in vivo. However, SIRT3 inhibition abolished the protective roles of melatonin in acute lung injury. Mechanistically, we found that melatonin increased the activity and expression of SIRT3, which further promoted the deacetylation of SOD2 at K122 and K68. More importantly, melatonin exerted pulmonary protection by activating MTNR1B but not MTNR1A during ALI. Collectively, melatonin could preserve the mitochondrial quality control of lung epithelial cells through the deacetylation of SOD2 in a SIRT3-dependent manner, which eventually alleviated sepsis-induced injury, inflammation, oxidative stress, and apoptosis. Thus, melatonin may serve as a promising candidate against ALI in the future.

The role of Mitochondrial Fission Proteins in Mitochondrial Dynamics in Kidney Disease

Mitochondria have many forms and can change their shape through fusion and fission of the outer and inner membranes, called "mitochondrial dynamics". Mitochondrial outer membrane proteins, such as mitochondrial fission protein 1 (FIS1), mitochondrial fission factor (MFF), mitochondrial 98 dynamics proteins of 49 kDa (MiD49), and mitochondrial dynamics proteins of 51 kDa (MiD51), can aggregate at the outer mitochondrial membrane and thus attract Dynamin-related protein 1 (DRP1) from the cytoplasm to the outer mitochondrial membrane, where DRP1 can perform a scissor-like function to cut a complete mitochondrion into two separate mitochondria. Other organelles can promote mitochondrial fission alongside mitochondria. FIS1 plays an important role in mitochondrial-lysosomal contacts, differentiating itself from other mitochondrial-fission-associated proteins. The contact between the two can also induce asymmetric mitochondrial fission. The kidney is a mitochondria-rich organ, requiring large amounts of mitochondria to produce energy for blood circulation and waste elimination. Pathological increases in mitochondrial fission can lead to kidney damage that can be ameliorated by suppressing their excessive fission. This article reviews the current knowledge on the key role of mitochondrial-fission-associated proteins in the pathogenesis of kidney injury and the role of their various post-translational modifications in activation or degradation of fission-associated proteins and targeted drug therapy.

SIRT3 alleviates mitochondrial dysfunction induced by recurrent low glucose and improves the supportive function of astrocytes to neurons

Hypoglycemia is an independent risk factor of cognitive impairment in patients with diabetes. Our previous study indicated that dysfunction of astrocytic mitochondria induced by recurrent low glucose (RLG) may account for hypoglycemia-associated neuronal injury and cognitive decline. Sirtuin 3 (SIRT3) is a key deacetylase for mitochondrial proteins and has recently been demonstrated to be an important regulator of mitochondrial function. However, whether mitochondrial dysfunction due to hypoglycemia is associated with astrocytic SIRT3 remains unclear, and few studies have focused on the impact of astrocytic SIRT3 on neuronal survival. In the present work, primary mouse cortical astrocytes cultured in normal glucose (5.5 mM) and high glucose (16.5 mM) were treated with five rounds of RLG (0.1 mM). The results showed that RLG suppressed SIRT3 expression in a glucose-dependent manner. High-glucose culture considerably increased the vulnerability of SIRT3 to RLG, leading to disrupted mitochondrial morphology in astrocytes. Overexpression of SIRT3 markedly improved astrocytic mitochondrial function and reduced RLG-induced oxidative stress. Moreover, SIRT3 suppressed a shift towards a neuroinflammatory A1-like reactive phenotype of astrocytes in response to RLG with reduced IL-1β, IL-6, and TNFα levels. Furthermore, it elevated brain-derived neurotrophic factor (BDNF) levels and promoted neurite growth by activating BDNF/TrkB signaling in the co-cultured neurons. The present study reveals the probable crosstalk between neurons and astrocytes after hypoglycemic exposure and provides a potential target in treating hypoglycemia-associated neuronal injury.

Hydrogen Sulfide Biomedical Research in China-20 Years of Hindsight

Hydrogen sulfide (H2S) is an important gasotransmitter that is produced by mammalian cells and performs profound physiological and pathophysiological functions. Biomedical research on H2S metabolism and function in China began 20 years ago, which pioneered the examination of the correlation of abnormal H2S metabolism and cardiovascular diseases. Over the last two decades, research teams in China have made numerous breakthrough discoveries on the effects of H2S metabolism on hypertension, atherosclerosis, pulmonary hypertension, shock, angiogenesis, chronic obstructive pulmonary disease, pain, iron homeostasis, and testicle function, to name a few. These research developments, carried by numerous research teams all over China, build nationwide research network and advance both laboratory study and clinical applications. An integrated and collaborative research strategy would further promote and sustain H2S biomedical research in China and in the world.

Sodium Thiosulphate-Loaded Liposomes Control Hydrogen Sulphide Release and Retain Its Biological Properties in Hypoxia-like Environment

Hypoxia, or insufficient oxygen availability is a common feature in the development of a myriad of cardiovascular-related conditions including ischemic disease. Hydrogen sulphide (H2S) donors, such as sodium thiosulphate (STS), are known for their cardioprotective properties. However, H2S due to its gaseous nature, is released and cleared rapidly, limiting its potential translation to clinical settings. For the first time, we developed and characterised liposome formulations encapsulating STS and explored their potential for modulating STS uptake, H2S release and the ability to retain pro-angiogenic and biological signals in a hypoxia-like environment mirroring oxygen insufficiency in vitro. Liposomes were prepared by varying lipid ratios and characterised for size, polydispersity and charge. STS liposomal encapsulation was confirmed by HPLC-UV detection and STS uptake and H2S release was assessed in vitro. To mimic hypoxia, cobalt chloride (CoCl2) was administered in conjunction with formulated and non-formulated STS, to explore pro-angiogenic and metabolic signals. Optimised liposomal formulation observed a liposome diameter of 146.42 ± 7.34 nm, a polydispersity of 0.22 ± 0.19, and charge of 3.02 ± 1.44 mV, resulting in 25% STS encapsulation. Maximum STS uptake (76.96 ± 3.08%) from liposome encapsulated STS was determined at 24 h. Co-exposure with CoCl2 and liposome encapsulated STS resulted in increased vascular endothelial growth factor mRNA as well as protein expression, enhanced wound closure and increased capillary-like formation. Finally, liposomal STS reversed metabolic switch induced by hypoxia by enhancing mitochondrial bioenergetics. These novel findings provide evidence of a feasible controlled-delivery system for STS, thus H2S, using liposome-based nanoparticles. Likewise, data suggests that in scenarios of hypoxia, liposomal STS is a good therapeutic candidate to sustain pro-angiogenic signals and retain metabolic functions that might be impaired by limited oxygen and nutrient availability.

Yap1 modulates cardiomyocyte hypertrophy via impaired mitochondrial biogenesis in response to chronic mechanical stress overload

Rationale: Chronic pressure overload is a major trigger of cardiac pathological hypertrophy that eventually leads to heart disease and heart failure. Understanding the mechanisms governing hypertrophy is the key to develop therapeutic strategies for heart diseases.

Methods: We built chronic pressure overload mice model by abdominal aortic constriction (AAC) to explore the features of Yes-associated protein 1 (YAP1). Then AAV-cTNT-Cre was applied to Yap1^F/F mice to induce mosaic depletion of YAP1. Myh6^CreERT2; H11^CAG-LSL-YAP1 mice were involved to establish YAP1 overexpression model by Tomaxifen injection. ATAC-seq and bioChIP-seq were used to explore the potential targets of YAP1, which were verified by a series of luciferase reporter assays. Dnm1l and Mfn1 were re-expressed in AAC mice by AAV-cTNT-Dnm1l and AAV-cTNT-Mfn1. Finally, Verteprofin was used to inhibit YAP1 to rescue cardiac hypertrophy.

Results: We found that pathological hypertrophy was accompanied with the activation of YAP1. Cardiomyocyte-specific deletion of Yap1 attenuated AAC-induced hypertrophy. Overexpression of YAP1 was sufficient to phenocopy AAC-induced hypertrophy. YAP1 activation resulted in the perturbation of mitochondria ultrastructure and function, which was associated with the repression of mitochondria dynamics regulators Dnm1l and Mfn1. Mitochondrial-related genes Dnm1l and Mfn1, are significantly targeted by TEAD1/YAP complex. Overexpression of Dnm1l and Mfn1 synergistically rescued YAP1-induced mitochondrial damages and cardiac hypertrophy. Pharmacological repression of YAP1 by verteporfin attenuated mitochondrial damages and pathological hypertrophy in AAC-treated mice. Interestingly, YAP1-induced mitochondria damages also led to increased reactive oxidative species, DNA damages, and the suppression of cardiomyocyte proliferation.

Conclusion: Together, these data uncovered YAP signaling as a therapeutic target for pressure overload-induced heart diseases and cautioned the efforts to induce cardiomyocyte regeneration by activating YAP.

The Mfn1-βIIPKC Interaction Regulates Mitochondrial Dysfunction via Sirt3 Following Experimental Subarachnoid Hemorrhage

Neuronal injury following subarachnoid hemorrhage (SAH) has been shown to be associated with mitochondrial dysfunction and oxidative stress. βIIPKC, a subtype of protein kinase C (PKC), accumulates on the mitochondrial outer membrane and phosphorylates mitofusin 1 (Mfn1) at serine 86. Here, we investigated the role of Mfn1-βIIPKC interaction in brain damage and neurological function in both in vivo and in vitro experimental SAH models. The expression of βIIPKC protein and the interaction of Mfn1-βIIPKC were found to be increased after OxyHb treatment in primary cultured cortical neurons and were also observed in the brain following SAH in rats. Treatment with the βIIPKC inhibitor βIIV5-3 or SAMβA, a peptide that selectively antagonizes Mfn1-βIIPKC association, significantly attenuated the OxyHb-induced neuronal injury and apoptosis. These protective effects were accompanied by inhibited mitochondrial dysfunction and preserved mitochondrial biogenesis. The results of western blot showed that βIIV5-3 or SAMβA markedly increased the expression of Sirt3 and enhanced the activities of its downstream mitochondrial antioxidant enzymes in OxyHb-treated neurons. Knockdown of Sirt3 via specific targeted small interfering RNA (siRNA) partially prevented the βIIV5-3- or SAMβA-induced protection and antioxidative effects. In addition, treatment with βIIV5-3 or SAMβA in vivo was found to obviously reduce brain edema, alleviate neuroinflammation, and preserve neurological function after experimental SAH in rats. In congruent with in vitro data, the protection induced by βIIV5-3 or SAMβA was reduced by Sirt3 knockdown in vivo. In summary, our present results showed that blocking Mfn1-βIIPKC interaction protects against brain damage and mitochondrial dysfunction via Sirt3 following experimental SAH.

Fucoxanthin ameliorated myocardial fibrosis in STZ-induced diabetic rats and cell hypertrophy in HG-induced H9c2 cells by alleviating oxidative stress and restoring mitophagy

Diabetic cardiomyopathy (DCM) is one of the leading causes of death in diabetic patients, and is accompanied by increased oxidative stress and mitochondrial dysfunction. Fucoxanthin (FX), as a marine carotenoid, possesses strong antioxidant activity. The main purpose of our study was to explore whether FX could attenuate experimental cardiac hypertrophy by affecting mitophagy and oxidative stress. We found that FX improved lipid metabolism, myocardial damage, myocardial fibrosis and hypertrophy in the myocardial tissue of STZ-induced diabetic rats. Additionally, FX upregulated Nrf2 signaling to reduce the level of reactive oxygen species (ROS). FX also promoted Bnip3/Nix signaling to improve mitochondrial function and reduced the levels of mitochondrial and intracellular ROS, thereby reversing HG-induced H9c2 cell hypertrophy. However, treatment with the autophagy inhibitor CQ abolished the anti-hypertrophic effect of FX, accompanied by impaired mitochondrial function and increased ROS levels. In conclusion, we found that FX reduced the accumulation of TGF-β1, FN and α-SMA to relieve myocardial fibrosis in STZ-induced diabetic rats, and FX up-regulated Bnip3/Nix to promote mitophagy and enhanced Nrf2 signaling to alleviate oxidative stress, thereby inhibiting hypertrophy in HG-induced H9c2 cells. These results imply that FX may be developed as a functional food for DCM.

Mitochonic Acid-5 Inhibits Reactive Oxygen Species Production and Improves Human Chondrocyte Survival by Upregulating SIRT3-Mediated, Parkin-dependent Mitophagy

Mitochondrial dysfunction is related to the pathogenesis of osteoarthritis (OA); however, there are no effective drugs to treat OA for maintaining mitochondrial homeostasis. Studies have shown that mitochonic acid-5 (MA-5) has a protective effect against mitochondrial damage and plays a role in mitophagy. However, it is not clear whether MA-5 has a beneficial effect on inflammatory articular cartilage. Here, human OA cartilage was obtained from patients undergoing total joint replacement. Interleukin-1β (IL-1β) was used to stimulate chondrocytes and induce inflammatory injury. Cell Counting Kit-8, TUNEL, and flow cytometry assays were used to assess apoptosis. Gene expression was examined using quantitative reverse transcription-polymerase chain reaction. Mitochondrial function was evaluated using immunoblotting, mitochondrial membrane potential assay, JC-1 staining, and immunofluorescence analysis. Mitophagy was detected using immunoblotting and immunofluorescence. 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP), a specific inhibitor of Sirtuin 3 (SIRT3), was used to block the SIRT3/Parkin pathway. Mitophagy in the cartilage sections was evaluated via immunohistochemistry. IL-1β was found to induce chondrocyte apoptosis by inhibiting SIRT3 expression and mitophagy. In addition, inflammatory damage reduced the mitochondrial membrane potential and promoted the production of intracellular reactive oxygen species (ROS), leading to increased mitochondrial division, mitochondrial fusion inhibition, and the consequent mitochondrial damage. In contrast, the MA-5 treatment inhibited excessive ROS production by upregulating mitophagy, maintaining the mitochondrial membrane potential, and reducing mitochondrial apoptosis. After chemically blocking SIRT3 with 3-TYP, Parkin-related mitophagy was also inhibited, an effect that was prevented by pretreatment of the chondrocytes with MA-5, thereby suggesting that SIRT3 is upstream of Parkin. Overall, MA-5 was found to enhance the activity of SIRT3, promote Parkin-dependent mitophagy, eliminate depolarized/damaged mitochondria in chondrocytes, and protect cartilage cells. In conclusion, MA-5 inhibits IL-1β-induced oxidative stress and protects chondrocytes by upregulating the SIRT3/Parkin-related autophagy signaling pathway.

SS31 Alleviates Pressure Overload-Induced Heart Failure Caused by Sirt3-Mediated Mitochondrial Fusion

Heart failure caused by pressure overload is one of the leading causes of heart failure worldwide, but its pathological origin remains poorly understood. It remains critical to discover and find new improvements and treatments for pressure overload-induced heart failure. According to previous studies, mitochondrial dysfunction and myocardial interstitial fibrosis are important mechanisms for the development of heart failure. The oligopeptide Szeto-Schiller Compound 31 (SS31) can specifically interact with the inner mitochondrial membrane and affect the integrity of the inner mitochondrial membrane. Whether SS31 alleviates pressure overload-induced heart failure through the regulation of mitochondrial fusion has not yet been confirmed. We established a pressure-overloaded heart failure mouse model through TAC surgery and found that SS31 can significantly improve cardiac function, reduce myocardial interstitial fibrosis, and increase the expression of optic atrophy-associated protein 1 (OPA1), a key protein in mitochondrial fusion. Interestingly, the role of SS31 in improving heart failure and reducing fibrosis is inseparable from the presence of sirtuin3 (Sirt3). We found that in Sirt3KO mice and fibroblasts, the effects of SS31 on improving heart failure and improving fibroblast transdifferentiation were disappeared. Likewise, Sirt3 has direct interactions with proteins critical for mitochondrial fission and fusion. We found that SS31 failed to increase OPA1 expression in both Sirt3KO mice and fibroblasts. Thus, SS31 can alleviate pressure overload-induced heart failure through Sirt3-mediated mitochondrial fusion. This study provides new directions and drug options for the clinical treatment of heart failure caused by pressure overload.

Mitochondrial-Targeted Therapies Require Mitophagy to Prevent Oxidative Stress Induced by SOD2 Inactivation in Hypertrophied Cardiomyocytes

Heart failure, mostly associated with cardiac hypertrophy, is a major cause of illness and death. Oxidative stress causes accumulation of reactive oxygen species (ROS), leading to mitochondrial dysfunction, suggesting that mitochondria-targeted therapies could be effective in this context. The purpose of this work was to determine whether mitochondria-targeted therapies could improve cardiac hypertrophy induced by mitochondrial ROS. We used neonatal (NCMs) and adult (ACMs) rat cardiomyocytes hypertrophied by isoproterenol (Iso) to induce mitochondrial ROS. A decreased interaction between sirtuin 3 and superoxide dismutase 2 (SOD2) induced SOD2 acetylation on lysine 68 and inactivation, leading to mitochondrial oxidative stress and dysfunction and hypertrophy after 24 h of Iso treatment. To counteract these mechanisms, we evaluated the impact of the mitochondria-targeted antioxidant mitoquinone (MitoQ). MitoQ decreased mitochondrial ROS and hypertrophy in Iso-treated NCMs and ACMs but altered mitochondrial structure and function by decreasing mitochondrial respiration and mitophagy. The same decrease in mitophagy was found in human cardiomyocytes but not in fibroblasts, suggesting a cardiomyocyte-specific deleterious effect of MitoQ. Our data showed the importance of mitochondrial oxidative stress in the development of cardiomyocyte hypertrophy. We observed that targeting mitochondria by MitoQ in cardiomyocytes impaired the metabolism through defective mitophagy, leading to accumulation of deficient mitochondria.

Early Protective Role of Inflammation in Cardiac Remodeling and Heart Failure: Focus on TNFα and Resident Macrophages

Cardiac hypertrophy, initiated by a variety of physiological or pathological stimuli (hemodynamic or hormonal stimulation or infarction), is a critical early adaptive compensatory response of the heart. The structural basis of the progression from compensated hypertrophy to pathological hypertrophy and heart failure is still largely unknown. In most cases, early activation of an inflammatory program reflects a reparative or protective response to other primary injurious processes. Later on, regardless of the underlying etiology, heart failure is always associated with both local and systemic activation of inflammatory signaling cascades. Cardiac macrophages are nodal regulators of inflammation. Resident macrophages mostly attenuate cardiac injury by secreting cytoprotective factors (cytokines, chemokines, and growth factors), scavenging damaged cells or mitochondrial debris, and regulating cardiac conduction, angiogenesis, lymphangiogenesis, and fibrosis. In contrast, excessive recruitment of monocyte-derived inflammatory macrophages largely contributes to the transition to heart failure. The current review examines the ambivalent role of inflammation (mainly TNFα-related) and cardiac macrophages (Mφ) in pathophysiologies from non-infarction origin, focusing on the protective signaling processes. Our objective is to illustrate how harnessing this knowledge could pave the way for innovative therapeutics in patients with heart failure.

RNA sequencing reveals novel LncRNA/mRNAs co-expression network associated with puerarin-mediated inhibition of cardiac hypertrophy in mice

Background

Evidence has demonstrated that puerarin is a potential medicine for the treatment of cardiac hypertrophy. However, the precise underlying molecular mechanisms of the protective effect of puerarin are still unclear. Here, we aimed to explore the regulatory mechanisms of lncRNAs/mRNAs co-expression network in a cardiac hypertrophy mouse model after puerarin treatment.

Methods

A mouse model of cardiac hypertrophy was established by transverse aortic constriction (TAC). The echocardiography, tissue staining and western blot were used to examine the protective effect of puerarin. Then RNA sequencing (RNA-seq) was carried out to analyze systematically mRNAs and lncRNAs expression. The target lncRNA were confirmed using qRT-PCR. Moreover, a coding/non-coding gene co-expression network were established to find the interaction of lncRNA and mRNAs. The biological process, cellular component, molecular function and pathways of different expression mRNAs targeted by lncRNA were explored using Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis.

Results

Puerarin exhibited an obvious inhibitory effect in cardiac hypertrophy in TAC model. RNA-seq analysis was performed to investigate the lncRNAs and mRNAs expression patterns of cardiomyocytes in sham and TAC groups treated with or without puerarin. RNA-seq identified that TAC downregulated four lncRNAs, which could be revised by puerarin treatment (|log2 Fold change| > 2 and FDR < 0.05). Among them, expression alterations of lncRNA Airn (antisense of Igf2r non-protein coding RNA) was confirmed by qRT-PCR. Pearson's correlation coefficients of co-expression levels suggested that there was an interactive relationship between Airn and 2,387 mRNAs (r > 0.95 or r < -0.95). Those co-expressed mRNAs were enriched in some important biological processes such as translational initiation, cell proliferation, insulin-like growth factor binding and poly(A) RNA binding. KEGG analyses suggested that those Airn-interacted mRNAs were enriched in endocytosis, signaling pathways regulating pluripotency of stem cells and the Jak-STAT pathway.

Conclusion

Puerarin may exert beneficial effects on cardiac hypertrophy through regulating the lncRNAs/mRNAs co-expression network.

Sirtuin 3 Dependent and Independent Effects of NAD+ to Suppress Vascular Inflammation and Improve Endothelial Function in Mice

Atherosclerosis is initiated by endothelial cell dysfunction and vascular inflammation under the condition of hyperlipidemia. Sirtuin 3 (SIRT3) is a nicotinamide adenine dinucleotide (NAD⁺)-dependent mitochondrial deacetylase, which plays a key role in maintaining normal mitochondrial function. The present study tested whether endothelial-selective SIRT3 deletion accelerates vascular inflammation and oxidative stress, and assessed the protective effect of NAD⁺ to alleviate these changes in endothelial cells and in mouse models of atherosclerosis. We found that the selective deletion of SIRT3 in endothelial cells further impaired endothelium-dependent vasodilatation in the aorta treated with IL-1β, which was accompanied by upregulation of vascular inflammation markers and mitochondrial superoxide overproduction. Excepting the dysfunction of endothelium-dependent vasodilatation, such effects could be attenuated by treatment with NAD⁺. In human umbilical vein endothelial cells, SIRT3 silencing potentiated the induction of inflammatory factors by IL-1β, including VCAM-1, ICAM-1, and MCP1, and the impairment of mitochondrial respiration, both of which were alleviated by NAD⁺ treatment. In ApoE-deficient mice fed with a high-cholesterol diet, supplementation with nicotinamide riboside, the NAD⁺ precursor, reduced plaque formation, improved vascular function, and diminished vascular inflammation. Our results support the SIRT3-dependent and -independent of NAD⁺ to improve endothelial function in atherosclerosis.

S-nitrosylation of c-Jun N-terminal kinase mediates pressure overload-induced cardiac dysfunction and fibrosis

Cardiac fibrosis (CF) is an irreversible pathological process that occurs in almost all kinds of cardiovascular diseases. Phosphorylation-dependent activation of c-Jun N-terminal kinase (JNK) induces cardiac fibrosis. However, whether S-nitrosylation of JNK mediates cardiac fibrosis remains an open question. A biotin-switch assay confirmed that S-nitrosylation of JNK (SNO-JNK) increased significantly in the heart tissues of hypertrophic patients, transverse aortic constriction (TAC) mice, spontaneously hypertensive rats (SHRs), and neonatal rat cardiac fibroblasts (NRCFs) stimulated with angiotensin II (Ang II). Site to site substitution of alanine for cysteine in JNK was applied to determine the S-nitrosylated site. S-Nitrosylation occurred at both Cys116 and Cys163 and substitution of alanine for cysteine 116 and cysteine 163 (C116/163A) inhibited Ang II-induced myofibroblast transformation. We further confirmed that the source of S-nitrosylation was inducible nitric oxide synthase (iNOS). 1400 W, an inhibitor of iNOS, abrogated the profibrotic effects of Ang II in NRCFs. Mechanistically, SNO-JNK facilitated the nuclear translocation of JNK, increased the phosphorylation of c-Jun, and induced the transcriptional activity of AP-1 as determined by chromatin immunoprecipitation and EMSA. Finally, WT and iNOS^-/- mice were subjected to TAC and iNOS knockout reduced SNO-JNK and alleviated cardiac fibrosis. Our findings demonstrate an alternative mechanism by which iNOS-induced SNO-JNK increases JNK pathway activity and accelerates cardiac fibrosis. Targeting SNO-JNK might be a novel therapeutic strategy against cardiac fibrosis.

Protective role of hydrogen sulfide against diabetic cardiomyopathy via alleviating necroptosis

Diabetic cardiomyopathy lacks effective and novel methods. Hydrogen sulfide (H₂S) as the third gasotransmitter plays an important role in the cardiovascular system. Our study was to elucidate the protective effect and possible mechanism of H₂S on diabetic cardiomyopathy from the perspective of necroptosis. Leptin receptor deficiency (db/db) mice and streptozotocin (STZ)-induced diabetic cystathionine-γ-lyase (CSE) knockout (KO) mice were investigated. In addition, cardiomyocytes were stimulated with high glucose. We found that plasma H₂S level, myocardial H₂S production and CSE mRNA expression was impaired in the diabetic mice. CSE deficiency exacerbated diabetic cardiomyopathy, and promoted myocardial oxidative stress, necroptosis and inflammasome in STZ-induced mice. CSE inhibitor dl-propargylglycine (PAG) aggravated cell damage and oxidative stress, deteriorated necroptosis and inflammasome in cardiomyocytes with high glucose stimulation. H₂S donor sodium hydrosulfide (NaHS) improved diabetic cardiomyopathy, attenuated myocardial oxidative stress, necroptosis and the NLR family pyrin domain-containing protein 3 (NLRP3) in db/db mice. NaHS also alleviated cell damage, oxidative stress, necroptosis and inflammasome in cardiomyocytes with high glucose stimulation. In Conclusion, H₂S deficiency aggravated mitochondrial damage, increased reactive oxygen species accumulation, promoted necroptosis, activated NLRP3 inflammasome, and finally exacerbated diabetic cardiomyopathy. Exogenous H₂S supplementation alleviated necroptosis to suppress NLRP3 inflammasome activation and attenuate diabetic cardiomyopathy via mitochondrial dysfunction improvement and oxidative stress inhibition. Our study provides the first evidence and a new mechanism that necroptosis inhibition by a pharmacological manner of H₂S administration protected against diabetic cardiomyopathy. It is beneficial to provide a novel strategy for the prevention and treatment of diabetic cardiomyopathy.

Sirt3, 6, and 7 Genes Expression in Gastric Antral Epithelial Cells of Patients with Helicobacter pylori Infection

Sirtuins, known as the intracellular acylation enzymes, play a major role in regulating the cell's physiological activities. The relevant studies have shown diversely sirtuin genes expression in various cancers in humans. This study has surveyed the transcription of sirt3, 6, and 7 genes in gastric antral epithelial cells (GAECs) of gastritis and gastric adenocarcinoma patients with and without Helicobacter pylori infection. First of all, a case-control study was conducted, including 50 and 53 gastric antral biopsy samples collected from gastritis and gastric adenocarcinoma patients with and without H. pylori infection referred to hospitals of Sanandaj City during 2018-2019. Total RNAs were extracted from biopsy samples, then cDNAs were synthesized by using TaKaRa kits. Quality essay of H. pylori virulence genes expression and relative quantitative essay of sirt3, 6, and 7 genes expressions in gastric antral biopsy samples were performed using the real-time RT-PCR method. The statistical analysis showed the significant correlations between H. pylori vacA s1m2 and sabA cDNAs with sirt3 geneś expression in GAECs (P < 0.05, 0.05 respectively). In addition, sirt6 gene's expression decreased along increasing age in gastric adenocarcinoma patients (P < 0.05). The samples of gastritis patients with gastric antral epithelial biopsy containing H. pylori hopQII, oipA, and sabB cDNA showed an increased amount of sirt7 genes expression (P < 0.05, 0.05, and 0.05 respectively). In conclusion, the H. pylori virulence genes expression and increasing age of patients showed the significant correlations with sirt3, 6, and 7 genes expressions in GAECs of gastric and gastric cancer patients.

Mitochondria in Pathological Cardiac Hypertrophy Research and Therapy

Cardiac hypertrophy, a stereotypic cardiac response to increased workload, ultimately progresses to severe contractile dysfunction and uncompensated heart failure without appropriate intervention. Sustained cardiac overload inevitably results in high energy consumption, thus breaking the balance between mitochondrial energy supply and cardiac energy demand. In recent years, accumulating evidence has indicated that mitochondrial dysfunction is implicated in pathological cardiac hypertrophy. The significant alterations in mitochondrial energetics and mitochondrial proteome composition, as well as the altered expression of transcripts that have an impact on mitochondrial structure and function, may contribute to the initiation and progression of cardiac hypertrophy. This article presents a summary review of the morphological and functional changes of mitochondria during the hypertrophic response, followed by an overview of the latest research progress on the significant modulatory roles of mitochondria in cardiac hypertrophy. Our article is also to summarize the strategies of mitochondria-targeting as therapeutic targets to treat cardiac hypertrophy.

Hesperetin derivative-16 attenuates CCl4-induced inflammation and liver fibrosis by activating AMPK/SIRT3 pathway

Liver fibrosis, a chronic inflammatory healing reaction, progresses to hepatocirrhosis without effective intervention. Hesperetin derivative (HD-16), a monomer compound derived from hesperitin, exerts anti-inflammatory and hepatoprotective effects against a spectrum of liver diseases. However, the anti-fibrotic potential of HD-16 in liver fibrosis and its underlying mechanism have not yet been elucidated. In this study, we investigated the anti-fibrotic effect of HD-16 on mouse liver fibrosis induced by CCl4 and on LX-2 cells (human immortalized HSCs) stimulated by TGF-β1, in vivo and in vitro. HD-16 exerted an anti-fibrotic effect via regulation of the AMPK/SIRT3 pathway. Pharmacodynamic results showed that HD-16 alleviated the degree of injury and inflammation in CCl4-induced mouse liver fibrosis. Consistently, HD-16 also effectively inhibited the expression of α-SMA, Col1α1, Col3α1, and TIMP-1 in TGF-β1-activated LX-2 cells. Mechanistically, HD-16 promoted SIRT3 expression and activity in fibrotic liver and activated LX-2 cells. Furthermore, SIRT3 depletion attenuated the anti-fibrotic effects of HD-16. Intriguingly, HD-16 increased AMPK phosphorylation, whereas inhibition of SIRT3 expression did not affect AMPK phosphorylation. In contrast, AMPK silencing suppressed SIRT3 expression, suggesting that SIRT3 is a downstream target of AMPK in liver fibrosis. Overall, HD-16 attenuated CCl4-induced liver inflammation and fibrosis by activating the AMPK/SIRT3 pathway, and HD-16 may be a potential anti-fibrotic compound in the treatment of liver fibrosis.

Hydrogen Sulfide Ameliorates Angiotensin II-Induced Atrial Fibrosis Progression to Atrial Fibrillation Through Inhibition of the Warburg Effect and Endoplasmic Reticulum Stress

Atrial fibrosis is the basis for the occurrence and development of atrial fibrillation (AF) and is closely related to the Warburg effect, endoplasmic reticulum stress (ERS) and mitochondrion dysfunctions-induced cardiomyocyte apoptosis. Hydrogen sulfide (H₂S) is a gaseous signalling molecule with cardioprotective, anti-myocardial fibrosis and improved energy metabolism effects. Nevertheless, the specific mechanism by which H₂S improves the progression of atrial fibrosis to AF remains unclear. A case-control study of patients with and without AF was designed to assess changes in H₂S, the Warburg effect, and ERS in AF. The results showed that AF can significantly reduce cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate thiotransferase (3-MST) expression and the H₂S level, induce cystathionine-β-synthase (CBS) expression; increase the Warburg effect, ERS and atrial fibrosis; and promote left atrial dysfunction. In addition, AngII-treated SD rats had an increased Warburg effect and ERS levels and enhanced atrial fibrosis progression to AF compared to wild-type SD rats, and these conditions were reversed by sodium hydrosulfide (NaHS), dichloroacetic acid (DCA) or 4-phenylbutyric acid (4-PBA) supplementation. Finally, low CSE levels in AngII-induced HL-1 cells were concentration- and time-dependent and associated with mitochondrial dysfunction, apoptosis, the Warburg effect and ERS, and these effects were reversed by NaHS, DCA or 4-PBA supplementation. Our research indicates that H₂S can regulate the AngII-induced Warburg effect and ERS and might be a potential therapeutic drug to inhibit atrial fibrosis progression to AF.

S-nitrosylation of Hsp90 promotes cardiac hypertrophy in mice through GSK3β signaling

Cardiac hypertrophy, as one of the major predisposing factors for chronic heart failure, lacks effective interventions. Exploring the pathogenesis of cardiac hypertrophy will reveal potential therapeutic targets. S-nitrosylation is a kind of posttranslational modification that occurs at active cysteines of proteins to mediate various cellular processes. We here identified heat shock protein 90 (Hsp90) as a highly S-nitrosylated target in the hearts of rodents with hypertrophy, and the role of Hsp90 in cardiac hypertrophy remains undefined. The S-nitrosylation of Hsp90 (SNO-Hsp90) levels were elevated in angiotensin II (Ang II)- or phenylephrine (PE)-treated neonatal rat cardiomyocytes (NRCMs) in vitro as well as in cardiomyocytes isolated from mice subjected to transverse aortic constriction (TAC) in vivo. We demonstrated that the elevated SNO-Hsp90 levels were mediated by decreased S-nitrosoglutathione reductase (GSNOR) expression during cardiac hypertrophy, and delivery of GSNOR adeno-associated virus expression vectors (AAV9-GSNOR) decreased the SNO-Hsp90 levels to attenuate cardiac hypertrophy. Mass spectrometry analysis revealed that cysteine 589 (Cys589) might be the S-nitrosylation site of Hsp90. Delivery of the mutated AAV9-Hsp90-C589A inhibited SNO-Hsp90 levels and attenuated cardiac hypertrophy. We further revealed that SNO-Hsp90 led to increased interaction of glycogen synthase kinase 3β (GSK3β) and Hsp90, leading to elevated GSK3β phosphorylation and decreased eIF2Bε phosphorylation, thereby aggravating cardiac hypertrophy. Application of GSK3β inhibitor TWS119 abolished the protective effect of Hsp90-C589A mutation in Ang II-treated NRCMs. In conclusion, this study demonstrates a critical role of SNO-Hsp90 in cardiac hypertrophy, which may be of a therapeutic target for cardiac hypertrophy treatment.

Cardioprotective effects of hydrogen sulfide in attenuating myocardial ischemia‑reperfusion injury (Review)

Ischemic heart disease is one of the major causes of cardiovascular‑related mortality worldwide. Myocardial ischemia can be attenuated by reperfusion that restores the blood supply. However, injuries occur during blood flow restoration that induce cardiac dysfunction, which is known as myocardial ischemia‑reperfusion injury (MIRI). Hydrogen sulfide (H₂S), the third discovered endogenous gasotransmitter in mammals (after NO and CO), participates in various pathophysiological processes. Previous in vitro and in vivo research have revealed the protective role of H₂S in the cardiovascular system that render it useful in the protection of the myocardium against MIRI. The cardioprotective effects of H₂S in attenuating MIRI are summarized in the present review.

Necroptosis Inhibition by Hydrogen Sulfide Alleviated Hypoxia-Induced Cardiac Fibroblasts Proliferation via Sirtuin 3

Myocardial ischemia or hypoxia can induce myocardial fibroblast proliferation and myocardial fibrosis. Hydrogen sulfide (H₂S) is a gasotransmitter with multiple physiological functions. In our present study, primary cardiac fibroblasts were incubated with H₂S donor sodium hydrosulfide (NaHS, 50 μM) for 4 h followed by hypoxia stimulation (containing 5% CO₂ and 1% O₂) for 4 h. Then, the preventive effects on cardiac fibroblast proliferation and the possible mechanisms were investigated. Our results showed that NaHS reduced the cardiac fibroblast number, decreased the hydroxyproline content; inhibited the EdU positive ratio; and down-regulated the expressions of α-smooth muscle actin (α-SMA), the antigen identified by monoclonal antibody Ki67 (Ki67), proliferating cell nuclear antigen (PCNA), collagen I, and collagen III, suggesting that hypoxia-induced cardiac fibroblasts proliferation was suppressed by NaHS. NaHS improved the mitochondrial membrane potential and attenuated oxidative stress, and inhibited dynamin-related protein 1 (DRP1), but enhanced optic atrophy protein 1 (OPA1) expression. NaHS down-regulated receptor interacting protein kinase 1 (RIPK1) and RIPK3 expression, suggesting that necroptosis was alleviated. NaHS increased the sirtuin 3 (SIRT3) expressions in hypoxia-induced cardiac fibroblasts. Moreover, after SIRT3 siRNA transfection, the inhibitory effects on cardiac fibroblast proliferation, oxidative stress, and necroptosis were weakened. In summary, necroptosis inhibition by exogenous H₂S alleviated hypoxia-induced cardiac fibroblast proliferation via SIRT3.

Protection of the enhanced Nrf2 deacetylation and its downstream transcriptional activity by SIRT1 in myocardial ischemia/reperfusion injury

Nrf2, the master gene transcriptor of antioxidant proteins, and SIRT1, the unique Class III histone deacetylase of sirtuins, have been involved in protecting myocardial ischemia/reperfusion (MI/R) injury. However, whether the protective effect of SIRT1 is directly related to the deacetylation of Nrf2 in the pathology of MI/R remains to be investigated. The current study was designed to evaluate the regulation of Nrf2 deacetylation and transcriptional activity by SIRT1 in MI/R. Hypoxia/reoxygenation (H/R) cardiomyocytes and MI/R mice were used to assess the role of SIRT1 in Nrf2 activation. Oxidative stress, cardiac function, LDH release, ROS and infarct size were also evaluated. We found that Nrf2 physically interacted with SIRT1 not only in normal and H/R cardiomyocytes in vitro, but also in Sham or I/R hearts in vivo. Adenovirus induced SIRT1 overexpression resulted in protected H/R induced cell death, accompanied by declined LDH release. Through MI/R in vivo, cardiac overexpression of SIRT1 led to ameliorated cardiac function and infarct size, as well as the decreased cardiac oxidative stress. Notably, such beneficial actions of SIRT1 were blocked by the Nrf2 silence. Mechanically, acetylation of Nrf2 was significantly decreased by SIRT1 overexpression in cardiomyocytes or in whole hearts, which upregulated the downstream signaling pathway of Nrf2. Taken together, we uncovered a clue, for the first time that SIRT1 physically interacts with Nrf2. The cardioprotective effect of SIRT1 overexpression against MI/R is associated with the increased Nrf2 deacetylation and activity. These findings have offered a direct proof and new perspective of post-translational modification in the understanding of oxidative stress and MI/R treatment.

Sirtuin 3 (SIRT3) Pathways in Age-Related Cardiovascular and Neurodegenerative Diseases

Age-associated cardiovascular and neurodegenerative diseases lead to high morbidity and mortality around the world. Sirtuins are vital enzymes for metabolic adaptation and provide protective effects against a wide spectrum of pathologies. Among sirtuins, mitochondrial sirtuin 3 (SIRT3) is an essential player in preserving the habitual metabolic profile. SIRT3 activity declines as a result of aging-induced changes in cellular metabolism, leading to increased susceptibility to endothelial dysfunction, hypertension, heart failure and neurodegenerative diseases. Stimulating SIRT3 activity via lifestyle, pharmacological or genetic interventions could protect against a plethora of pathologies and could improve health and lifespan. Thus, understanding how SIRT3 operates and how its protective effects could be amplified, will aid in treating age-associated diseases and ultimately, in enhancing the quality of life in elders.

Hydrogen sulfide plays a potential alternative for the treatment of metabolic disorders of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a cardiovascular complication that tends to occur in patients with diabetes, obesity, or insulin resistance, with a higher late mortality rate. Sustained hyperglycemia, increased free fatty acids, or insulin resistance induces metabolic disorders in cardiac tissues and cells, leading to myocardial fibrosis, left ventricular hypertrophy, diastolic and/or systolic dysfunction, and finally develop into congestive heart failure. The close connection between all signaling pathways and the complex pathogenesis of DCM cause difficulties in finding effective targets for the treatment of DCM. It reported that hydrogen sulfide (H₂S) could regulate cell energy substrate metabolism, reduce insulin resistance, protect cardiomyocytes, and improve myocardial function by acting on related key proteins such as differentiation cluster 36 (CD36) and glucose transporter 4 (GLUT4). In this article, the relative mechanisms of H₂S in alleviating metabolic disorders of DCM were reviewed, and how H₂S can better prevent and treat DCM in clinical practice will be discussed.

Hydrogen Sulfide Attenuates Angiotensin II-Induced Cardiac Fibroblast Proliferation and Transverse Aortic Constriction-Induced Myocardial Fibrosis through Oxidative Stress Inhibition via Sirtuin 3

Sirtuin 3 (SIRT3) is critical in mitochondrial function and oxidative stress. Our present study investigates whether hydrogen sulfide (H₂S) attenuated myocardial fibrosis and explores the possible role of SIRT3 on the protective effects. Neonatal rat cardiac fibroblasts were pretreated with NaHS followed by angiotensin II (Ang II) stimulation. SIRT3 was knocked down with siRNA technology. SIRT3 promoter activity and expression, as well as mitochondrial function, were measured. Male wild-type (WT) and SIRT3 knockout (KO) mice were intraperitoneally injected with NaHS followed by transverse aortic constriction (TAC). Myocardium sections were stained with Sirius red. Hydroxyproline content, collagen I and collagen III, α-smooth muscle actin (α-SMA), and dynamin-related protein 1 (DRP1) expression were measured both in vitro and in vivo. We found that NaHS enhanced SIRT3 promoter activity and increased SIRT3 mRNA expression. NaHS inhibited cell proliferation and hydroxyproline secretion, decreased collagen I, collagen III, α-SMA, and DRP1 expression, alleviated oxidative stress, and improved mitochondrial respiration function and membrane potential in Ang II-stimulated cardiac fibroblasts, which were unavailable after SIRT3 was silenced. In vivo, NaHS reduced hydroxyproline content, ameliorated perivascular and interstitial collagen deposition, and inhibited collagen I, collagen III, and DRP1 expression in the myocardium of WT mice but not SIRT3 KO mice with TAC. Altogether, NaHS attenuated myocardial fibrosis through oxidative stress inhibition via a SIRT3-dependent manner.

Mitochondrial proteins in heart failure: The role of deacetylation by SIRT3

Heart failure (HF) is still the leading cause of death worldwide, occurring with a variety of complex mechanisms. However, most intervention for HF do not directly target the pathological mechanisms underlying cell damage in failing cardiomyocytes. Mitochondria are involved in many physiological processes, which is an important guarantee for normal heart function. Mitochondrial dysfunction is considered to be the critical node of the development of HF. Strict modulation of the mitochondrial function can ameliorate the myocardial injury and protect cardiac function. Acetylation plays an important role in mitochondrial protein homeostasis, and SIRT3, the most important deacetylation protein in mitochondria, is involved in the maintenance of mitochondrial function. SIRT3 can delay the progression of HF by improving mitochondrial function. Herein we summarize the interaction between SIRT3 and proteins related to mitochondrial function including oxidative phosphorylation (OXPHOS), fatty acid oxidation (FAO), mitochondrial biosynthesis, mitochondrial quality control. In addition, we also sum up the effects of this interaction on HF and the research progress of treatments targeting SIRT3, so as to find potential HF therapeutic for clinical use in the future.

Inhibition of HSP90 S-nitrosylation Alleviates Cardiac Fibrosis via TGFβ/SMAD3 Signaling Pathway

BACKGROUND AND PURPOSE

Effective anti-fibrotic therapeutic solutions are unavailable so far. The heat shock protein 90 (HSP90) exerts deleterious effects in some fibrotic diseases. S-nitrosylation (SNO) of HSP90 affects its own function, however, little is known about its role in pathological stress. Here, we investigated the effect of SNO-HSP90 on cardiac fibrosis.

EXPERIMENTAL APPROACH

SNO-HSP90 level was measured by biotin-switch. SNO sites were identified through mass spectrometry. S-nitrosylation site-mutated plasmids or adeno-associated virus, gene deletion and pharmacological antagonists were used to identify the contribution of SNO-HSP90 in myocardial fibrosis.

KEY RESULTS

SNO-HSP90 level was positively correlated with fibrosis marker expression in hearts from patients and significantly higher in fibrotic hearts from spontaneously hypertensive rats and mice subjected to transverse aortic constriction, as well as in angiotensin II- or isoproterenol-treated neonatal rat cardiac fibroblasts. S-nitrosylated site of HSP90 at cysteine 589 was identified. Inhibition of SNO-HSP90 by Cys589 mutation reduced fibrosis in angiotensin II- or isoproterenol-treated cardiac fibroblasts. Administration of recombinant adeno-associated virus of Cys589 mutation improved heart function and alleviated fibrosis in transverse aortic constriction mice. Mechanismly, SNO-HSP90 stimulated transforming growth factor-β type II receptor (TGFβ RII) binding to HSP90 in response to fibrotic stimuli, subsequently increased phosphorylation and nuclear translocation of SMAD3. Additionally, inducible nitric oxide synthase (iNOS) deficiency or iNOS inhibitor, 1400W, reduced SNO-HSP90 level and the activation of TGFβ/SMAD3 signaling pathway.

CONCLUSIONS AND IMPLICATIONS

We demonstrate that genetic or pharmacological inhibition of SNO-HSP90 mitigates fibrosis through blocking TGFβ/SMAD3 signaling pathway, providing a potential therapy for cardiac remodeling.

Protective role of sirtuin3 against oxidative stress and NLRP3 inflammasome in cholesterol accumulation and foam cell formation of macrophages with ox-LDL-stimulation

Sirtuin3 (SIRT3) is involved in reactive oxygen species (ROS), cell metabolism, apoptosis and inflammation. However, the exact role of SIRT3 in macrophages during pathophysiological process of atherosclerosis remains unclear. The present study was to investigate the possible effects and mechanisms of SIRT3 on lipid uptake and foam cells transforming in oxidized low-density lipoprotein (ox-LDL)-stimulated macrophages. Compared with wild-type (WT) mice, SIRT3 deficiency further increased foam cell formation and cellular cholesterol accumulation, exacerbated oxidative stress, impaired mitochondrial permeability potential, decreased optic atrophy 1 (OPA1) but enhanced dynamin-related protein 1 (DRP1) expression, and promoted NLR family pyrin domain-containing protein 3 (NLRP3) activation in ox-LDL-stimulated macrophages from SIRT3 knockout (KO) mice. Dihydromyricetin (DMY), a potential compound to enhance SIRT3 expression, significantly inhibited cellular cholesterol accumulation, suppressed foam cell formation, improved mitochondrial function, attenuated oxidative stress, and alleviated NLRP3 activation in ox-LDL-stimulated macrophages. Moreover, above protective effects of DMY was unavailable in macrophages from SIRT3 KO mice. Collectively, the study demonstrated the protective role of SIRT3 against oxidative stress and NLRP3 inflammasome in cholesterol accumulation and foam cell formation of macrophages with ox-LDL-stimulation, which is beneficial to provide novel strategy for atherosclerosis prevention and treatment.