The role of sirtuins in cardiac disease

The growing landscape of succinylation links metabolism and heart disease

Post-translational modification of proteins is an important biochemical process that occurs at the protein level. Succinylation is a newly discovered post-translational modification with the hallmark of a significant chemical and structural change. Succinylation has many similarities with other modifications, but succinylation may lead to more functional changes. Although the physiological significance of succinylation has not been well characterized, the lysine succinylation modification shows great potentials during disease processes. The discovery of SIRT5 has made great progress in exploring the role of succinylation in energy metabolism, heart disease and tumorigenesis. In this review, we focus on the discovery of succinylation in organisms and mechanism of succinylation. We are also concerned with the metabolic reactions and heart diseases associated with succinylation.

The Role of Posttranslational Modification and Mitochondrial Quality Control in Cardiovascular Diseases

Cardiovascular disease (CVD) is the leading cause of death in the world. The mechanism behind CVDs has been studied for decades; however, the pathogenesis is still controversial. Mitochondrial homeostasis plays an essential role in maintaining the normal function of the cardiovascular system. The alterations of any protein function in mitochondria may induce abnormal mitochondrial quality control and unexpected mitochondrial dysfunction, leading to CVDs. Posttranslational modifications (PTMs) affect protein function by reversibly changing their conformation. This review summarizes how common and novel PTMs influence the development of CVDs by regulating mitochondrial quality control. It provides not only ideas for future research on the mechanism of some types of CVDs but also ideas for CVD treatments with therapeutic potential.

Resveratrol's Anti-Cancer Effects through the Modulation of Tumor Glucose Metabolism

Simple Summary

The prevention and treatment of cancer is an ongoing medical challenge. In the context of personalized medicine, the well-studied polyphenol resveratrol could complement classical tumor therapy. It may affect key processes such as inflammation, angiogenesis, proliferation, metastasis, glucose metabolism, and apoptosis in various cancers because resveratrol acts as a multi-targeting agent by modulating multiple signal transduction pathways. This review article focuses on resveratrol’s ability to modify tumor glucose metabolism and its associated therapeutic capacity. Resveratrol reduces glucose uptake and glycolysis by affecting Glut1, PFK1, HIF-1α, ROS, PDH, and the CamKKB/AMPK pathway. It also inhibits cell growth, invasion, and proliferation by targeting NF-kB, Sirt1, Sirt3, LDH, PI-3K, mTOR, PKM2, R5P, G6PD, TKT, talin, and PGAM. In addition, resveratrol induces apoptosis by targeting integrin, p53, LDH, and FAK. In conclusion, resveratrol has many potentials to intervene in tumor processes if bioavailability can be increased and this natural compound can be used selectively.

Abstract

Tumor cells develop several metabolic reprogramming strategies, such as increased glucose uptake and utilization via aerobic glycolysis and fermentation of glucose to lactate; these lead to a low pH environment in which the cancer cells thrive and evade apoptosis. These characteristics of tumor cells are known as the Warburg effect. Adaptive metabolic alterations in cancer cells can be attributed to mutations in key metabolic enzymes and transcription factors. The features of the Warburg phenotype may serve as promising markers for the early detection and treatment of tumors. Besides, the glycolytic process of tumors is reversible and could represent a therapeutic target. So-called mono-target therapies are often unsafe and ineffective, and have a high prevalence of recurrence. Their success is hindered by the ability of tumor cells to simultaneously develop multiple chemoresistance pathways. Therefore, agents that modify several cellular targets, such as energy restriction to target tumor cells specifically, have therapeutic potential. Resveratrol, a natural active polyphenol found in grapes and red wine and used in many traditional medicines, is known for its ability to target multiple components of signaling pathways in tumors, leading to the suppression of cell proliferation, activation of apoptosis, and regression in tumor growth. Here, we describe current knowledge on the various mechanisms by which resveratrol modulates glucose metabolism, its potential as an imitator of caloric restriction, and its therapeutic capacity in tumors.

The functional medicine approach to atrial fibrillation: can a cure for atrial fibrillation be found in the gut?

PURPOSE OF REVIEW

The importance of addressing the proximal causes of atrial fibrillation is recognized, yet frustration with the currently applied preventive measures is high. This review describes the functional medicine model (FMM), which identifies the proximal causes of atrial fibrillation at the level of gene-environment interaction.

RECENT FINDINGS

The pathological processes leading to atrial fibrillation sustaining disorder have been elucidated in translational studies and are described as 'nodal points.' Examples are inflammation, oxidative stress, autoimmune mechanisms, and visceral adiposity. These same nodal points also cause disorder that results in atrial fibrillation-related complications and the development of atrial fibrillation-associated diseases. These nodal points vary from patient to patient and can be identified by careful evaluation of the patients clinical phenotype.

SUMMARY

The application of the FMM identifies the gene--environment interactions that facilitate the patients nodal points and corrects them with emphasis on personalized diet, nutrition, and lifestyle changes.

Elevated plasma Sirtuin2 level predicts heart failure after acute myocardial infarction

Background

There is currently no evidence regarding the role of plasma Sirtuin2 (SIRT2) level in acute myocardial infarction (AMI) yet. This study assessed the role of plasma SIRT2 in AMI, and investigated the association of plasma SIRT2 level with major adverse cardiovascular events (MACE) and heart failure after AMI.

Methods

This is a prospective observational study. A total of 129 AMI patients (mean age: 62.2±12.7 years old, male/female: 96/33) were included. Cox proportional hazards regression models were used to estimate the association of different SIRT2 levels with MACE and heart failure after AMI.

Results

According to the 75th percentile value of plasma SIRT2 level, we divided all the AMI patients into two groups: high-level group (plasma SIRT2 level ≥109.0 pg/mL) and low-level group (plasma SIRT2 level <109.0 pg/mL). Compared with the low-level group, the high-level group had higher percentage of Killip class ≥3 (P<0.001), left ventricular ejection fraction (LVEF) <50% (P=0.007) or even <40% (P=0.012), use of breathing machine(P=0.003), and higher plasma brain natriuretic peptide (BNP) level (P=0.006). Multivariate Cox regression analysis showed that there were higher risks of MACE [hazard ratio (HR) 11.20, 95% confidence interval (CI): 3.18–39.52, P<0.001)] and heart failure (HR 27.10, 95% CI: 4.65–157.83, P<0.001) in the high-level group.

Conclusions

The present study suggested that plasma SIRT2 level is a promising biomarker to predict heart failure and MACE after AMI.

Role of hydrogen in traumatic brain injury: a narrative review

Traumatic brain injury (TBI) is a serious global public health problem. Survivors of TBI often suffer from long-term disability, which puts a heavy burden on society and families. Unfortunately, up to now, there is no efficacious treatment for TBI patients in clinical practice. As a reducing gas, hydrogen has been shown to be neuroprotective in multiple cerebral disease models; however, its efficacy in TBI remains controversial. In this review, we will focus on the results of hydrogen in experimental TBI, elaborate the potential mechanisms, and put forward for future researches based on our current understanding and views.

Nicotinamide riboside reduces cardiometabolic risk factors and modulates cardiac oxidative stress in obese Wistar rats under caloric restriction

AIMS

NAD-based therapeutic strategies are encouraged against obesity and heart disease. Our study, therefore, aimed to investigate the effects of nicotinamide riboside (NR), isolated or combined with caloric restriction (CR), both approaches well-known for stimulating NAD levels, on adiposity parameters, cardiometabolic factors and cardiac oxidative stress in rats submitted to cafeteria diet (CAF).

MAIN METHODS

After 42 days of CAF-induced obesity (hypercaloric and ultra-processed foods common to humans), we examined the effects of oral administration of NR (400 mg/kg for 28 days), combined or not with CR (-62% kcal, for 28 days), on anthropometric, metabolic, tissue, and cardiac oxidative stress parameters in obese male Wistar rats.

KEY FINDINGS

In obese rats, treatment with NR alone mitigated final body weight gain, reduced adiposity (visceral and subcutaneous), improved insulin resistance, and decreased TG/HDL ratio and heart size. In cardiac OS, treatment with NR increased the antioxidant capacity via glutathione peroxidase and catalase enzymes (in rats under CR) as well as reduced the pro-oxidant complex NADPH oxidase (in obese and lean rats). Hyperglycemia, hypertriglyceridemia and elevated levels of TBARS in the heart were state-dependent adverse effects, induced by treatment with NR.

SIGNIFICANCE

This is the first study to report effects of nicotinamide riboside on cardiac oxidative stress in an obesity model. Nicotinamide riboside, a natural dietary compound, presented antiobesity effects and cardiometabolic benefits, in addition to positively modulating oxidative stress in the heart, in a state-dependent manner.

Sinapic Acid Inhibits Cardiac Hypertrophy via Activation of Mitochondrial Sirt3/SOD2 Signaling in Neonatal Rat Cardiomyocytes

Sinapic acid (SA) is a naturally occurring phenolic compound with antioxidant properties. It also has a wide range of pharmacological properties, such as anti-inflammatory, anticancer, and hepatoprotective properties. The present study aimed to evaluate the potential pharmacological effects of SA against hypertrophic responses in neonatal rat cardiomyocytes. In order to evaluate the preventive effect of SA on cardiac hypertrophy, phenylephrine (PE)-induced hypertrophic cardiomyocytes were treated with subcytotoxic concentrations of SA. SA effectively suppressed hypertrophic responses, such as cell size enlargement, sarcomeric rearrangement, and fetal gene re-expression. In addition, SA significantly inhibited the expression of mitogen-activated protein kinase (MAPK) proteins as pro-hypertrophic factors and protected the mitochondrial functions from hypertrophic stimuli. Notably, SA activated Sirt3, a mitochondrial deacetylase, and SOD2, a mitochondrial antioxidant, in hypertrophic cardiomyocytes. SA also inhibited oxidative stress in hypertrophic cardiomyocytes. However, the protective effect of SA was significantly reduced in Sirt3-silenced hypertrophic cardiomyocytes, indicating that SA exerts its beneficial effect through Sirt3/SOD signaling. In summary, this is the first study to reveal the potential pharmacological action and inhibitory mechanism of SA as an antioxidant against cardiac hypertrophy, suggesting that SA could be utilized for the treatment of cardiac hypertrophy.

A systematic review of post-translational modifications in the mitochondrial permeability transition pore complex associated with cardiac diseases

The mitochondrial permeability transition pore (mPTP) opening is involved in the pathophysiology of multiple cardiac diseases, such as ischemia/reperfusion injury and heart failure. A growing number of evidence provided by proteomic screening techniques has demonstrated the role of post-translational modifications (PTMs) in several key components of the pore in response to changes in the extra/intracellular environment and bioenergetic demand. This could lead to a fine, complex regulatory mechanism that, under pathological conditions, can shift the state of mitochondrial functions and, thus, the cell's fate. Understanding the complex relationship between these PTMs is still under investigation and can provide new, promising therapeutic targets and treatment approaches. This review, using a systematic review of the literature, presents the current knowledge on PTMs of the mPTP and their role in health and cardiac disease.

DPP-4 inhibitor induces FGF21 expression via sirtuin 1 signaling and improves myocardial energy metabolism

Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used incretin-based therapy for the treatment of type 2 diabetes. We investigated the cardioprotective effect of a DPP-4 inhibitor, vildagliptin (vilda), on myocardial metabolism and cardiac performance under pressure overload. Mice were treated with either vehicle or vilda, followed by transverse aortic constriction (TAC). After 3 weeks of TAC, cardiac hypertrophy and impairment of systolic function were attenuated in vilda-treated mice. Pressure-volume analysis showed that vilda treatment significantly improved left-ventricular contractile efficiency in TAC heart. Myocardial energy substrate analysis showed that vilda treatment significantly increased glucose uptake as well as fatty acid uptake. Fibroblast growth factor 21 (FGF21), a peptide involved in the regulation of energy metabolism, increased in TAC heart and was further increased by vilda treatment. FGF21 was strongly expressed in cardiac fibroblasts than in cardiomyocytes in mouse heart after TAC with vilda treatment. Vilda treatment markedly induced FGF21 expression in human cardiac fibroblasts through a sirtuin (Sirt) 1-mediated pathway, suggesting that fibroblast-mediated FGF21 expression may regulate energy metabolism and exert vilda-mediated beneficial effects in stressed heart. Vilda induced a metabolic regulator, FGF21 expression in cardiac fibroblasts via Sirt1, and increased contractile efficiency in murine pressure-overloaded heart.

Activation of SIRT1/PGC 1α/SIRT3 pathway by melatonin provides protection against mitochondrial dysfunction in isoproterenol induced myocardial injury

AIMS

Preventing mitochondrial dysfunction and enhancing mitochondrial health and biogenesis is a crucial therapeutic approach to ameliorate injury following acute myocardial infarction. Although the antioxidant role of melatonin against ischemia/reperfusion injury has been reported, the exact mechanism of protection, in vivo, remains poorly understood. This study aims to identify and elaborate upon mechanism of melatonin protection of rat cardiac mitochondria against acute myocardial infarction.

MAIN METHODS

Rats were pre-treated with melatonin (10 mg/kg body weight (b.w.); intraperitoneally, i.p.) before isoproterenol bitartrate (ISO) administration (25 mg/kg body weight (b.w.) subcutaneously,s.c.) and their effect on rat heart mitochondrial structure and function was studied. Biochemical changes in activity of biomarkers of oxidative stress, antioxidant enzymes as well as Krebs' cycle enzymes were analyzed. Gene expression studies and Isothermal titration calorimetric studies with pure catalase and ISO were also carried out.

KEY FINDINGS

Melatonin was shown to reduce ISO induced oxidative stress, by stimulating superoxide dismutase activity and removing the inhibition of Krebs' cycle enzymes. Herein we report for the first time in rat model that melatonin activates the SIRT1-PGC-1α-SIRT3 signaling pathways after ISO administration, which ultimately induces mitochondrial biogenesis. Melatonin exhibited significant protection of mitochondrial architecture and topology along with increased calcium ion permeability and reactive oxygen species (ROS) generation induced by ISO. Isothermal calorimetric studies revealed that melatonin binds to ISO molecules and sequesters them from the reaction thereby limiting their interaction with catalase along with occupying the binding sites of catalase themselves.

SIGNIFICANCE

Activation of SIRT1-PGC-1α-SIRT3 pathway by melatonin along with its biophysical properties prevents ISO induced mitochondrial injury in rat heart.

Bakuchiol Alleviates Hyperglycemia-Induced Diabetic Cardiomyopathy by Reducing Myocardial Oxidative Stress via Activating the SIRT1/Nrf2 Signaling Pathway

Bakuchiol (BAK), a monoterpene phenol reported to have exerted a variety of pharmacological effects, has been related to multiple diseases, including myocardial ischemia reperfusion injury, pressure overload-induced cardiac hypertrophy, diabetes, liver fibrosis, and cancer. However, the effects of BAK on hyperglycemia-caused diabetic cardiomyopathy and its underlying mechanisms remain unclear. In this study, streptozotocin-induced mouse model and high-glucose-treated cell model were conducted to investigate the protective roles of BAK on diabetic cardiomyopathy, in either the presence or absence of SIRT1-specific inhibitor EX527, SIRT1 siRNA, or Nrf2 siRNA. Our data demonstrated for the first time that BAK could significantly abate diabetic cardiomyopathy by alleviating the cardiac dysfunction, ameliorating the myocardial fibrosis, mitigating the cardiac hypertrophy, and reducing the cardiomyocyte apoptosis. Furthermore, BAK achieved its antifibrotic and antihypertrophic actions by inhibiting the TGF-β1/Smad3 pathway, as well as decreasing the expressions of fibrosis- and hypertrophy-related markers. Intriguingly, these above effects of BAK were largely attributed to the remarkable activation of SIRT1/Nrf2 signaling, which eventually strengthened cardiac antioxidative capacity by elevating the antioxidant production and reducing the reactive oxygen species generation. However, all the beneficial results were markedly abolished with the administration of EX527, SIRT1 siRNA, or Nrf2 siRNA. In summary, these novel findings indicate that BAK exhibits its therapeutic properties against hyperglycemia-caused diabetic cardiomyopathy by attenuating myocardial oxidative damage via activating the SIRT1/Nrf2 signaling.

Sirtuin 6: A potential therapeutic target for cardiovascular diseases

Cardiovascular diseases (CVDs) are serious diseases endangering human health due to high morbidity and mortality worldwide, and numerous signal molecules are involved in this pathological process. As a member of the Sirtuin family NAD ⁺-dependent deacetylases, indeed, Sirtuin 6 (SIRT6) plays an important role in regulating biological homeostasis, longevity, and various diseases. More importantly, SIRT6 performs as an indispensable role in glucose and lipid metabolism, inflammation and genomic stability for the occurrence and development of various CVDs. Recent advances: among sirtuins, SIRT6 was frequently unveiled thanks for its protective roles against heart failure, cardiovascular remodeling and atherosclerosis, and identified as an essential intervention target of CVDs, bringing SIRT6 into the focus of clinical interest. Herein, we provide an overview of the current molecular mechanism through which SIRT6 regulates CVDs, and we highlight a potential therapeutic target for CVDs.

Adiponectin agonist ADP355 ameliorates doxorubicin-induced cardiotoxicity by decreasing cardiomyocyte apoptosis and oxidative stress

Doxorubicin (DOX) is an anthracycline derivative and widely used as an anticancer drug. However, the severe cardiotoxicity of DOX limits its application. ADP355 is an adiponectin-based active peptide with anti-liver fibrosis and atherosclerosis properties. It remains unclear the effects and involved mechanisms of ADP355 in DOX-induced cardiotoxicity. C57BL/6J mice were intraperitoneally injected DOX once a week to induce heart failure while receiving ADP355 treatment daily for 4 weeks. At the end of experiment, blood and heart tissues were collected. We found that ADP355 markedly improved DOX-induced cardiac dysfunction and histopathological damage, and decreased serum creatine kinase, lactate dehydrogenase and hydroxybutyrate dehydrogenase levels. The anti-apoptotic activity of ADP355 was indicated by reduction in TUNEL-positive cells and cleaved caspase-3 expression, along with decreased BCL2-associated X protein/B cell lymphoma 2 (BAX/BCL2) levels in heart tissues. Additionally, ADP355 markedly increased DOX-decreased cell viability by reducing BAX/BCL2, but inhibited reactive oxygen species production in H9c2 cells. Mechanistically, ADP355 attenuated expression of DOX-reduced nuclear factor-erythroid 2-related factor 2 (Nrf2) and superoxide dismutase 2, as well as mRNA levels of Nrf2 downstream targets. Furthermore, ADP355 activated sirtuin 2 and its target genes. In conclusion, we demonstrate that ADP355 alleviates DOX-induced cardiotoxicity by inhibiting myocardial apoptosis and oxidative stress through Nrf2 and sirtuin 2 signaling pathways. These findings suggest that ADP355 can be a promising candidate for the treatment of cardiac dysfunction.

Small molecule inhibition of cyclic GMP-AMP synthase ameliorates sepsis-induced cardiac dysfunction in mice

AIMS

Cardiac dysfunction is the main cause of multi-organ failure following sepsis within critical care units. The present study aimed to investigate the effects of the small molecule inhibition of cyclic GMP-AMP synthase (cGAS), RU.521, on cardiac function in mice with sepsis.

MATERIALS AND METHODS

Sepsis was induced in mice via intraperitoneal lipopolysaccharide (LPS) injection (10 mg/kg, i.p.). Mice subsequently received 5 mg/kg RU.521 within 10 min form LPS injection. The cardiac function, inflammatory factor and oxidative stress of mice were examined for 24 h following LPS injection.

KEY FINDINGS

RU.521 was indicated to significantly increase the cardiac function of mice with sepsis. In addition, the inflammatory responses, oxidative stress and apoptosis in hearts of sepsis mice were markedly mitigated by RU.521. Moreover, inhibition of Sirt3 inhibited the protective effects of RU.521 on mice with sepsis.

SIGNIFICANCE

The current study indicated that RU.521 alleviated the inflammatory response and alleviated the damage induced by oxidative stress, leading to cardiac protection via increased Sirt3 expression in the hearts of mice with sepsis.

Cardioprotective effects of miR-34a silencing in a rat model of doxorubicin toxicity

Cardiotoxicity remains a serious problem in anthracycline-treated oncologic patients. Therapeutic modulation of microRNA expression is emerging as a cardioprotective approach in several cardiovascular pathologies. MiR-34a increased in animals and patients exposed to anthracyclines and is involved in cardiac repair. In our previous study, we demonstrated beneficial effects of miR-34a silencing in rat cardiac cells exposed to doxorubicin (DOXO). The aim of the present work is to evaluate the potential cardioprotective properties of a specific antimiR-34a (Ant34a) in an experimental model of DOXO-induced cardiotoxicity. Results indicate that in our model systemic administration of Ant34a completely silences miR-34a myocardial expression and importantly attenuates DOXO-induced cardiac dysfunction. Ant34a systemic delivery in DOXO-treated rats triggers an upregulation of prosurvival miR-34a targets Bcl-2 and SIRT1 that mediate a reduction of DOXO-induced cardiac damage represented by myocardial apoptosis, senescence, fibrosis and inflammation. These findings suggest that miR-34a therapeutic inhibition may have clinical relevance to attenuate DOXO-induced toxicity in the heart of oncologic patients.

Dual role of sirtuin 1 in inflammatory bowel disease

Silent information regulator-1 (SIRT-1), is a member of the class III group of histone deacetylases and is collectively called sirtuins. There have been preclinical and clinical studies indicating the downregulation and decreased activity of sirtuin 1 in various inflammatory bowel disease models. Furthermore, the downregulation of sirtuin 1 is responsible for the sustained production of proinflammatory cytokines and the generation of oxidative stress in colitis. Hyperacetylation of NF-κB and HSF-1 (heat shock factor-1) in the absence of sirtuin1 is responsible for the induction of colitis. Accordingly, exogenous administration of sirtuin1 activators has been shown to attenuate the colitis in various inflammatory bowel disease models. On the other hand, the knockdown of sirtuin 1 gene or pharmacologic inhibition of sirtuin 1 has also been shown to be protective in the colitis. The deletion of the sirtuin1 gene may be helpful in the improvement of the disease condition of colitis through the maintenance of gastrointestinal immune homeostasis. The current review highlights the dual role of sirtuin 1 in the different experimental models of IBD along with possible mechanisms.

The Hyperoxic-Hypoxic Paradox

Effective metabolism is highly dependent on a narrow therapeutic range of oxygen. Accordingly, low levels of oxygen, or hypoxia, are one of the most powerful inducers of gene expression, metabolic changes, and regenerative processes, including angiogenesis and stimulation of stem cell proliferation, migration, and differentiation. The sensing of decreased oxygen levels (hypoxia) or increased oxygen levels (hyperoxia), occurs through specialized chemoreceptor cells and metabolic changes at the cellular level, which regulate the response. Interestingly, fluctuations in the free oxygen concentration rather than the absolute level of oxygen can be interpreted at the cellular level as a lack of oxygen. Thus, repeated intermittent hyperoxia can induce many of the mediators and cellular mechanisms that are usually induced during hypoxia. This is called the hyperoxic-hypoxic paradox (HHP). This article reviews oxygen physiology, the main cellular processes triggered by hypoxia, and the cascade of events triggered by the HHP.

The Hyperoxic-Hypoxic Paradox

Effective metabolism is highly dependent on a narrow therapeutic range of oxygen. Accordingly, low levels of oxygen, or hypoxia, are one of the most powerful inducers of gene expression, metabolic changes, and regenerative processes, including angiogenesis and stimulation of stem cell proliferation, migration, and differentiation. The sensing of decreased oxygen levels (hypoxia) or increased oxygen levels (hyperoxia), occurs through specialized chemoreceptor cells and metabolic changes at the cellular level, which regulate the response. Interestingly, fluctuations in the free oxygen concentration rather than the absolute level of oxygen can be interpreted at the cellular level as a lack of oxygen. Thus, repeated intermittent hyperoxia can induce many of the mediators and cellular mechanisms that are usually induced during hypoxia. This is called the hyperoxic-hypoxic paradox (HHP). This article reviews oxygen physiology, the main cellular processes triggered by hypoxia, and the cascade of events triggered by the HHP.

A Mitochondrial Approach to Cardiovascular Risk and Disease

BACKGROUND

Cardiovascular diseases (CVDs) are a leading risk factor for mortality worldwide and the number of CVDs victims is predicted to rise through 2030. While several external parameters (genetic, behavioral, environmental and physiological) contribute to cardiovascular morbidity and mortality; intrinsic metabolic and functional determinants such as insulin resistance, hyperglycemia, inflammation, high blood pressure and dyslipidemia are considered to be dominant factors.

METHODS

Pubmed searches were performed using different keywords related with mitochondria and cardiovascular disease and risk. In vitro, animal and human results were extracted from the hits obtained.

RESULTS

High cardiac energy demand is sustained by mitochondrial ATP production, and abnormal mitochondrial function has been associated with several lifestyle- and aging-related pathologies in the developed world such as diabetes, non-alcoholic fatty liver disease (NAFLD) and kidney diseases, that in turn can lead to cardiac injury. In order to delay cardiac mitochondrial dysfunction in the context of cardiovascular risk, regular physical activity has been shown to improve mitochondrial parameters and myocardial tolerance to ischemia-reperfusion (IR). Furthermore, pharmacological interventions can prevent the risk of CVDs. Therapeutic agents that can target mitochondria, decreasing ROS production and improve its function have been intensively researched. One example is the mitochondria-targeted antioxidant MitoQ10, which already showed beneficial effects in hypertensive rat models. Carvedilol or antidiabetic drugs also showed protective effects by preventing cardiac mitochondrial oxidative damage.

CONCLUSION

This review highlights the role of mitochondrial dysfunction in CVDs, also show-casing several approaches that act by improving mitochondrial function in the heart, contributing to decrease some of the risk factors associated with CVDs.

Sex differences in the aging human heart: decreased sirtuins, pro-inflammatory shift and reduced anti-oxidative defense

Aging is associated with increased inflammation and alterations in mitochondrial biogenesis, which promote the development of cardiovascular diseases. Emerging evidence suggests a role for sirtuins, which are NAD⁺-dependent deacetylases, in the regulation of cardiovascular inflammation and mitochondrial biogenesis. Sirtuins are regulated by sex or sex hormones and are decreased during aging in animal models. We hypothesized that age-related alterations in cardiac Sirt1 and Sirt3 occur in the human heart and examined whether these changes are associated with a decrease in anti-oxidative defense, inflammatory state and mitochondrial biogenesis. Using human ventricular tissue from young (17-40 years old) and old (50-68 years old) individuals, we found significantly lower Sirt1 and Sirt3 expression in old female hearts than in young female hearts. Additionally, lower expression of the anti-oxidative protein SOD2 was observed in old female hearts than in young female hearts. Aging in female hearts was associated with a significant increase in the number of cardiac macrophages and pro-inflammatory cytokines, as well as NF-kB upregulation, indicating a pro-inflammatory shift. Aging-associated pathways in the male hearts were different, and no changes in Sirt1 and Sirt3 or cardiovascular inflammation were observed. In conclusion, the present study revealed a female sex-specific downregulation of Sirt1 and Sirt3 in aged hearts, as well as a decline in mitochondrial anti-oxidative defense and a pro-inflammatory shift in old female hearts but not in male hearts.

Unveiling the Role of Inflammation and Oxidative Stress on Age-Related Cardiovascular Diseases

The global population above 60 years has been growing exponentially in the last decades, which is accompanied by an increase in the prevalence of age-related chronic diseases, highlighting cardiovascular diseases (CVDs), such as hypertension, atherosclerosis, and heart failure. Aging is the main risk factor for these diseases. Such susceptibility to disease is explained, at least in part, by the increase of oxidative stress, in which it damages cellular components such as proteins, DNA, and lipids. In addition, the chronic inflammatory process in aging “inflammaging” also contributes to cell damage, creating a stressful environment which drives to the development of CVDs. Taken together, it is possible to identify the molecular connection between oxidative stress and the inflammatory process, especially by the crosstalk between the transcription factors Nrf-2 and NF-κB which are mediated by redox signalling and are involved in aging. Therapies that control this process are key targets in the prevention/combat of age-related CVDs. In this review, we show the basics of inflammation and oxidative stress, including the crosstalk between them, and the implications on age-related CVDs.

Cardiomyocyte ageing and cardioprotection: consensus document from the ESC working groups cell biology of the heart and myocardial function

Advanced age is a major predisposing risk factor for the incidence of coronary syndromes and comorbid conditions which impact the heart response to cardioprotective interventions. Advanced age also significantly increases the risk of developing post-ischaemic adverse remodelling and heart failure after ischaemia/reperfusion (IR) injury. Some of the signalling pathways become defective or attenuated during ageing, whereas others with well-known detrimental consequences, such as glycoxidation or proinflammatory pathways, are exacerbated. The causative mechanisms responsible for all these changes are yet to be elucidated and are a matter of active research. Here, we review the current knowledge about the pathophysiology of cardiac ageing that eventually impacts on the increased susceptibility of cells to IR injury and can affect the efficiency of cardioprotective strategies.

Yin Yang 1 Is Essential for Transcriptional Activation of the Bovine Sirt2 Gene in Preadipocytes

Sirtuin 2 (Sirt2) belongs to the NAD⁺-dependent deacetylase family, is more highly expressed than other family members in adipocytes, and plays crucial roles in a wide range of biological processes. However, the mechanisms underlying Sirt2 expression during adipogenesis are poorly studied. In this study, the transcriptional start site (TSS) of Sirt2 was identified and two alternative transcript variants were spliced from Sirt2. The 5'-regulatory region of Sirt2 was also characterized; no TATA-box or CCAAT-box was presented in the 5'-flanking region. Two cytosine-phosphate diester-guanine (CpG) islands were also identified between nucleotides -563 and +4. A dual-luciferase reporter assay revealed that a 178 base pair sequence upstream from the TSS (+1) was the core promoter of Sirt2. Results from a site-directed mutagenesis experiment, electrophoretic mobility shift assay, and chromatin immunoprecipitation assay indicated Yin Yang 1 (YY1) to be a positive regulator of bovine Sirt2 in preadipocytes. YY1 is likely to suppress adipogenesis in two different ways by regulating peroxisome proliferator-activated receptor gamma expression. Our results expand the information on the regulatory network of adipogenesis, which is an important basis for improving beef quality, treating obesity, and other related diseases.

The effect of Sirt1 deficiency on Ca2+ and Na+ regulation in mouse ventricular myocytes

This study addressed the hypothesis that cardiac Sirtuin 1 (Sirt1) deficiency alters cardiomyocyte Ca²⁺ and Na⁺ regulation, leading to cardiac dysfunction and arrhythmogenesis. We used mice with cardiac‐specific Sirt1 knockout (Sirt1^−/−). Sirt1^flox/flox mice were served as control. Sirt1^−/− mice showed impaired cardiac ejection fraction with increased ventricular spontaneous activity and burst firing compared with those in control mice. The arrhythmic events were suppressed by KN93 and ranolazine. Reduction in Ca²⁺ transient amplitudes and sarcoplasmic reticulum (SR) Ca²⁺ stores, and increased SR Ca²⁺ leak were shown in the Sirt1^−/− mice. Electrophysiological measurements were performed using patch‐clamp method. While L‐type Ca²⁺ current (I_{Ca, L}) was smaller in Sirt1^−/− myocytes, reverse‐mode Na⁺/Ca²⁺ exchanger (NCX) current was larger compared with those in control myocytes. Late Na⁺ current (I_{Na, L}) was enhanced in the Sirt1^−/− mice, alongside with elevated cytosolic Na⁺ level. Increased cytosolic and mitochondrial reactive oxygen species (ROS) were shown in Sirt1^−/− mice. Sirt1^−/− cardiomyocytes showed down‐regulation of L‐type Ca²⁺ channel α1c subunit (Cav1.2) and sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase 2a (SERCA2a), but up‐regulation of Ca²⁺/calmodulin‐dependent protein kinase II and NCX. In conclusions, these findings suggest that deficiency of Sirt1 impairs the regulation of intracellular Ca²⁺ and Na⁺ in cardiomyocytes, thereby provoking cardiac dysfunction and arrhythmogenesis.

Pharmacological basis and new insights of resveratrol action in the cardiovascular system

Resveratrol (trans-3,4',5-trihydroxystilbene) belongs to the family of natural phytoalexins. Resveratrol first came to our attention in 1992, following reports of the cardioprotective effects of red wine. Thereafter, resveratrol was shown to exert antioxidant, anti-inflammatory, anti-proliferative, and angio-regulatory effects against atherosclerosis, ischaemia, and cardiomyopathy. This article critically reviews the current findings on the molecular basis of resveratrol-mediated cardiovascular benefits, summarizing the broad effects of resveratrol on longevity regulation, energy metabolism, stress resistance, exercise mimetics, circadian clock, and microbiota composition. In addition, this article also provides an update, both preclinically and clinically, on resveratrol-induced cardiovascular protection and discusses the adverse and inconsistent effects of resveratrol reported in both preclinical and clinical studies. Although resveratrol has been claimed as a master anti-aging agent against several age-associated diseases, further detailed mechanistic investigation is still required to thoroughly unravel the therapeutic value of resveratrol against cardiovascular diseases at different stages of disease development. LINKED ARTICLES: This article is part of a themed section on The Pharmacology of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.6/issuetoc.

Hydrogen Gas Attenuates Hypoxic-Ischemic Brain Injury via Regulation of the MAPK/HO-1/PGC-1a Pathway in Neonatal Rats

Neonatal hypoxic-ischemic encephalopathy (HIE) is a leading cause of death in neonates with no effective treatments. Recent advancements in hydrogen (H₂) gas offer a promising therapeutic approach for ischemia reperfusion injury; however, the impact of this approach for HIE remains a subject of debate. We assessed the therapeutic effects of H₂ gas on HIE and the underlying molecular mechanisms in a rat model of neonatal hypoxic-ischemic brain injury (HIBI). H₂ inhalation significantly attenuated neuronal injury and effectively improved early neurological outcomes in neonatal HIBI rats as well as learning and memory in adults. This protective effect was associated with initiation time and duration of sustained H₂ inhalation. Furthermore, H₂ inhalation reduced the expression of Bcl-2-associated X protein (BAX) and caspase-3 while promoting the expression of Bcl-2, nuclear factor erythroid-2-related factor 2, and heme oxygenase-1 (HO-1). H₂ activated extracellular signal-regulated kinase and c-Jun N-terminal protein kinase and dephosphorylated p38 mitogen-activated protein kinase (MAPK) in oxygen-glucose deprivation/reperfusion (OGD/R) nerve growth factor-differentiated PC12 cells. Inhibitors of MAPKs blocked H₂-induced HO-1 expression. HO-1 small interfering RNA decreased the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and sirtuin 1 (SIRT1) and reversed the protectivity of H₂ against OGD/R-induced cell death. These findings suggest that H₂ augments cellular antioxidant defense capacity through activation of MAPK signaling pathways, leading to HO-1 expression and subsequent upregulation of PGC-1α and SIRT-1 expression. Thus, upregulation protects NGF-differentiated PC12 cells from OGD/R-induced oxidative cytotoxicity. In conclusion, H₂ inhalation exerted protective effects on neonatal rats with HIBI. Early initiation and prolonged H₂ inhalation had better protective effects on HIBI. These effects of H₂ may be related to antioxidant, antiapoptotic, and anti-inflammatory responses. HO-1 plays an important role in H₂-mediated protection through the MAPK/HO-1/PGC-1α pathway. Our results support further assessment of H₂ as a potential therapeutic for neurological conditions in which oxidative stress and apoptosis are implicated.

Age and Sex Differences in Hearts of Soluble Epoxide Hydrolase Null Mice

Biological aging is an inevitable part of life that has intrigued individuals for millennia. The progressive decline in biological systems impacts cardiac function and increases vulnerability to stress contributing to morbidity and mortality in aged individuals. Yet, our understanding of the molecular, biochemical and physiological mechanisms of aging as well as sex differences is limited. There is growing evidence indicating CYP450 epoxygenase-mediated metabolites of n-3 and n-6 polyunsaturated fatty acids (PUFAs) are active lipid mediators regulating cardiac homeostasis. These epoxy metabolites are rapidly hydrolyzed and inactivated by the soluble epoxide hydrolase (sEH). The current study characterized cardiac function in young and aged sEH null mice compared to the corresponding wild-type (WT) mice. All aged mice had significantly increased cardiac hypertrophy, except in aged female sEH null mice. Cardiac function as assessed by echocardiography demonstrated a marked decline in aged WT mice, notably significant decreases in ejection fraction and fractional shortening in both sexes. Interestingly, aged female sEH null mice had preserved systolic function, while aged male sEH null mice had preserved diastolic function compared to aged WT mice. Assessment of cardiac mitochondria demonstrated an increased expression of acetyl Mn-SOD levels that correlated with decreased Sirt-3 activity in aged WT males and females. Conversely, aged sEH null mice had preserved Sirt-3 activity and better mitochondrial ultrastructure compared to WT mice. Consistent with these changes, the activity level of SOD significantly decreased in WT animals but was preserved in aged sEH null animals. Markers of oxidative stress demonstrated age-related increase in protein carbonyl levels in WT and sEH null male mice. Together, these data highlight novel cardiac phenotypes from sEH null mice demonstrating a sexual dimorphic pattern of aging in the heart.

Protein Subdomain Enrichment of NUP155 Variants Identify a Novel Predicted Pathogenic Hotspot

Functional variants in nuclear envelope genes are implicated as underlying causes of cardiopathology. To examine the potential association of single nucleotide variants of nucleoporin genes with cardiac disease, we employed a prognostic scoring approach to investigate variants of NUP155, a nucleoporin gene clinically linked with atrial fibrillation. Here we implemented bioinformatic profiling and predictive scoring, based on the gnomAD, National Heart Lung and Blood Institute-Exome Sequencing Project (NHLBI-ESP) Exome Variant Server, and dbNSFP databases to identify rare single nucleotide variants (SNVs) of NUP155 potentially associated with cardiopathology. This predictive scoring revealed 24 SNVs of NUP155 as potentially cardiopathogenic variants located primarily in the N-terminal crescent-shaped domain of NUP155. In addition, a predicted NUP155 R672G variant prioritized in our study was mapped to a region within the alpha helical stack of the crescent domain of NUP155. Bioinformatic analysis of inferred protein-protein interactions of NUP155 revealed over representation of top functions related to molecular transport, RNA trafficking, and RNA post-transcriptional modification. Topology analysis revealed prioritized hubs critical for maintaining network integrity and informational flow that included FN1, SIRT7, and CUL7 with nodal enrichment of RNA helicases in the topmost enriched subnetwork. Furthermore, integration of the top 5 subnetworks to capture network topology of an expanded framework revealed that FN1 maintained its hub status, with elevation of EED, CUL3, and EFTUD2. This is the first study to report novel discovery of a NUP155 subdomain hotspot that enriches for allelic variants of NUP155 predicted to be clinically damaging, and supports a role for RNA metabolism in cardiac disease and development.

Sirtuins as novel targets in the pathogenesis of airway inflammation in bronchial asthma

Sirtuins are NAD-dependent class III histone deacetylase, which modulate the epigenetic changes to influence the functions in normal and diseased conditions. Preclinical studies have described an increase in the levels of sirtuin 2 and decrease in the levels of sirtuin 6 in the lungs. Sirtuin 2 exerts proinflammatory actions and hence, its blockers reduce the airway inflammation and symptoms of asthma. On the other hand, sirtuin 6 is anti-inflammatory and its activators produce beneficial actions in asthma. The beneficial effects of sirtuin 6 have been attributed to decrease in acetylation of transcriptional factor GATA3 in the T cells, which is associated with decrease in the TH2 immune response. However, there seems to be dual role of sirtuin 1 in airway inflammation as its proinflammatory as well as anti-inflammatory actions have been described in asthma. The anti-inflammatory actions of sirtuin 1 have been attributed to decrease in acetylation of GATA3 and inhibition of Akt/NF-kappaB signaling. On the other hand, proinflammatory actions of sirtuin 1 have been attributed to increase in the expression of HIF-1α and VEGF along with repression of PPAR-γ activity. The present review discusses the role of different sirtuins in the pathogenesis of bronchial asthma. Moreover, it also discusses sirtuin-triggered signaling pathways that may contribute in modulating the disease state of bronchial asthma.

Hyperacetylation of Cardiac Mitochondrial Proteins Is Associated with Metabolic Impairment and Sirtuin Downregulation after Chronic Total Body Irradiation of ApoE -/- Mice

Chronic exposure to low-dose ionizing radiation is associated with an increased risk of cardiovascular disease. Alteration in energy metabolism has been suggested to contribute to radiation-induced heart pathology, mitochondrial dysfunction being a hallmark of this disease. The goal of this study was to investigate the regulatory role of acetylation in heart mitochondria in the long-term response to chronic radiation. ApoE-deficient C57Bl/6J mice were exposed to low-dose-rate (20 mGy/day) gamma radiation for 300 days, resulting in a cumulative total body dose of 6.0 Gy. Heart mitochondria were isolated and analyzed using quantitative proteomics. Radiation-induced proteome and acetylome alterations were further validated using immunoblotting, enzyme activity assays, and ELISA. In total, 71 proteins showed peptides with a changed acetylation status following irradiation. The great majority (94%) of the hyperacetylated proteins were involved in the TCA cycle, fatty acid oxidation, oxidative stress response and sirtuin pathway. The elevated acetylation patterns coincided with reduced activity of mitochondrial sirtuins, increased the level of Acetyl-CoA, and were accompanied by inactivation of major cardiac metabolic regulators PGC-1 alpha and PPAR alpha. These observations suggest that the changes in mitochondrial acetylation after irradiation is associated with impairment of heart metabolism. We propose a novel mechanism involved in the development of late cardiac damage following chronic irradiation.

Inducible Cardiac-Specific Deletion of Sirt1 in Male Mice Reveals Progressive Cardiac Dysfunction and Sensitization of the Heart to Pressure Overload

Heart failure is associated with profound alterations of energy metabolism thought to play a major role in the progression of this syndrome. SIRT1 is a metabolic sensor of cellular energy and exerts essential functions on energy metabolism, oxidative stress response, apoptosis, or aging. Importantly, SIRT1 deacetylates the peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α), the master regulator of energy metabolism involved in mitochondrial biogenesis and fatty acid utilization. However, the exact role of SIRT1 in controlling cardiac energy metabolism is still incompletely understood and conflicting results have been obtained. We generated a cardio-specific inducible model of Sirt1 gene deletion in mice (Sirt1^ciKO) to decipher the role of SIRT1 in control conditions and following cardiac stress induced by pressure overload. SIRT1 deficiency induced a progressive cardiac dysfunction, without overt alteration in mitochondrial content or properties. Sixteen weeks after Sirt1 deletion an increase in mitochondrial reactive oxygen species (ROS) production and a higher rate of oxidative damage were observed, suggesting disruption of the ROS production/detoxification balance. Following pressure overload, cardiac dysfunction and alteration in mitochondrial properties were exacerbated in Sirt1^ciKO mice. Overall the results demonstrate that SIRT1 plays a cardioprotective role on cardiac energy metabolism and thereby on cardiac function.

The Protective Mechanism of Cannabidiol in Cardiac Injury: A Systematic Review of Non-Clinical Studies

Background:

Cardiac disease is accounted as the leading cause of worldwide morbidity and mortality. The disease is characterized by the overproduction of reactive oxygen and/or nitrogen species (ROS/RNS), and induction of oxidative stress. Cannabidiol (CBD) is a non-psychoactive ingredient of marijuana that has been reported to be safe and well tolerated in patients. Due to its pleiotropic effect, CBD has been shown to exert cytoprotective effects. This study intended to clarify the mechanisms and the potential role of CBD regarding cardiac injuries treatment.

Methods:

A systematic literature search was conducted, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, in the electronic databases including PubMed, Web of Science, Scopus, and Embase up to June 2019 using predefined search terms in the titles and abstracts. Accordingly, a set of pre-specified inclusion and exclusion criteria were considered and 8 articles were ultimately included in this study.

Results:

Our findings demonstrate that CBD has multi-functional protective assets to improve cardiac injuries; preliminary through scavenging of free radicals, and reduction of oxidative stress, apoptosis, and inflammation.

Conclusion:

CBD can protect against cardiac injuries, mainly through its antioxidative and antiapoptotic effects on the basis of non-clinical studies. The cardioprotective effects of the CBD need to be further studied in welldesigned clinical trials.

MicroRNAs in Cardiac Hypertrophy

Like other organs, the heart undergoes normal adaptive remodeling, such as cardiac hypertrophy, with age. This remodeling, however, is intensified under stress and pathological conditions. Cardiac remodeling could be beneficial for a short period of time, to maintain a normal cardiac output in times of need; however, chronic cardiac hypertrophy may lead to heart failure and death. MicroRNAs (miRNAs) are known to have a role in the regulation of cardiac hypertrophy. This paper reviews recent advances in the field of miRNAs and cardiac hypertrophy, highlighting the latest findings for targeted genes and involved signaling pathways. By targeting pro-hypertrophic genes and signaling pathways, some of these miRNAs alleviate cardiac hypertrophy, while others enhance it. Therefore, miRNAs represent very promising potential pharmacotherapeutic targets for the management and treatment of cardiac hypertrophy.

Epigenomes in Cardiovascular Disease

Supplemental Digital Content is available in the text.

If unifying principles could be revealed for how the same genome encodes different eukaryotic cells and for how genetic variability and environmental input are integrated to impact cardiovascular health, grand challenges in basic cell biology and translational medicine may succumb to experimental dissection. A rich body of work in model systems has implicated chromatin-modifying enzymes, DNA methylation, noncoding RNAs, and other transcriptome-shaping factors in adult health and in the development, progression, and mitigation of cardiovascular disease. Meanwhile, deployment of epigenomic tools, powered by next-generation sequencing technologies in cardiovascular models and human populations, has enabled description of epigenomic landscapes underpinning cellular function in the cardiovascular system. This essay aims to unpack the conceptual framework in which epigenomes are studied and to stimulate discussion on how principles of chromatin function may inform investigations of cardiovascular disease and the development of new therapies.

Cardiac ageing: extrinsic and intrinsic factors in cellular renewal and senescence

Cardiac ageing manifests as a decline in function leading to heart failure. At the cellular level, ageing entails decreased replicative capacity and dysregulation of cellular processes in myocardial and nonmyocyte cells. Various extrinsic parameters, such as lifestyle and environment, integrate important signalling pathways, such as those involving inflammation and oxidative stress, with intrinsic molecular mechanisms underlying resistance versus progression to cellular senescence. Mitigation of cardiac functional decline in an ageing organism requires the activation of enhanced maintenance and reparative capacity, thereby overcoming inherent endogenous limitations to retaining a youthful phenotype. Deciphering the molecular mechanisms underlying dysregulation of cellular function and renewal reveals potential interventional targets to attenuate degenerative processes at the cellular and systemic levels to improve quality of life for our ageing population. In this Review, we discuss the roles of extrinsic and intrinsic factors in cardiac ageing. Animal models of cardiac ageing are summarized, followed by an overview of the current and possible future treatments to mitigate the deleterious effects of cardiac ageing.

Dual peroxisome-proliferator-activated-receptor-α/γ activation inhibits SIRT1-PGC1α axis and causes cardiac dysfunction

Dual peroxisome proliferator-activated receptor (PPAR)α/γ agonists that were developed to target hyperlipidemia and hyperglycemia in type 2 diabetes patients, caused cardiac dysfunction or other adverse effects. We studied the mechanisms that underlie the cardiotoxic effects of a dual PPARα/γ agonist, tesaglitazar, in wild type and diabetic (leptin receptor deficient - db/db) mice. Mice treated with tesaglitazar-containing chow or high fat diet developed cardiac dysfunction despite lower plasma triglycerides and glucose levels. Expression of cardiac peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), which promotes mitochondrial biogenesis, had the most profound reduction among various fatty acid metabolism genes. Furthermore, we observed increased acetylation of PGC1α, which suggests PGC1α inhibition and lowered sirtuin 1 (SIRT1) expression. This change was associated with lower mitochondrial abundance. Combined pharmacological activation of PPARα and PPARγ in C57BL/6 mice reproduced the reduction of PGC1α expression and mitochondrial abundance. Resveratrol-mediated SIRT1 activation attenuated tesaglitazar-induced cardiac dysfunction and corrected myocardial mitochondrial respiration in C57BL/6 and diabetic mice but not in cardiomyocyte-specific Sirt1-/- mice. Our data shows that drugs, which activate both PPARα and PPARγ lead to cardiac dysfunction associated with PGC1α suppression and lower mitochondrial abundance likely due to competition between these two transcription factors.

Screening Analysis of Sirtuins Family Expression on Anti-Inflammation of Resveratrol in Endothelial Cells

Background

Resveratrol has been shown to possess beneficial activities including antioxidant, anti-inflammatory, and cardioprotective effects through activating a nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase family member sirtuin-1 (SIRT1) protein. The current study was undertaken to investigate the role of sirtuin family members (SIRT1–SIRT7) on the anti-inflammation activities of resveratrol in endothelial cells.

Material/Methods

Primary human umbilical vein endothelial cells (HUVECs) were pretreated with resveratrol before tumor necrosis factor (TNF)-α (10–20 μg/L) stimulation. Cell viability was measured using the Cell Counting Kit-8 method. Total RNA was extracted after different treatments and the NimbleGen Human 12×135K Gene Expression Array was applied to screen and analyze SIRTs expression. Quantitative real-time polymerase chain reaction and western blot were applied to verify the results of the gene expression microarrays. Reactive oxygen species (ROS) production was examined using flow cytometry analysis.

Results

Microarray analysis showed that the expressions of SIRT1, SIRT2, SIRT3, SIRT5, SIRT6, and SIRT7 showed the tendency to increase while SIRT4 showed the tendency to decrease. SIRT1, SIRT2, SIRT5, and SIRT7 gene expression could be upregulated by pretreatment with resveratrol compared with TNF-α alone while there were no obvious differences of SIRT3, SIRT4, and SIRT6 expressions observed in TNF-α alone treated cells and resveratrol-TNF-α co-treated cells. Interestingly, SIRT1, SIRT2, SIRT3, SIRT4, and SIRT5 siRNA could reverse the effect of resveratrol on ROS production; SIRT1 and SIRT5 siRNA could significantly increase CD40 expression inhibited by resveratrol in TNF-α treated cells.

Conclusions

Our results suggest that resveratrol inhibiting oxidative stress production is associated with SIRT1, SIRT2, SIRT3, SIRT4, and SIRT5 pathways; attenuating CD40 expression was only associated with SIRT1 and SIRT5 pathways in TNF-α-induced endothelial cells injury.

microRNA-34a aggravates coxsackievirus B3-induced apoptosis of cardiomyocytes through the SIRT1-p53 pathway

Viral myocarditis is inflammation of the myocardium mainly caused by a viral infection, and coxsackievirus B3 (CVB3) infection is one of the most common. It is well known that cardiomyocyte apoptosis is involved in the pathogenesis of viral myocarditis. microRNAs (miRNAs, miRs) are endogenous noncoding oligoribonucleotides involved in various pathological conditions, and miR-34a is one of the miRNAs causing apoptosis. Whether miR-34a participates in cardiomyocyte apoptosis during CVB3 infection and the underlying mechanisms is still unclear. In this in vitro study, we found that miR-34a expression increased in cardiomyocytes after CVB3 infection. Furthermore, we found that CVB3 infection augmented histone deacetylase 1 (HDAC1) and Bax expression while inhibiting sirtuin 1 (SIRT1) and Bcl-2 expression, along with the acetylated p53 (Ac-p53) upregulation in cardiomyocytes. The above-mentioned phenomenon was reversed by a miR-34a inhibitor after CVB3 infection. In addition, the Ac-p53 amount increased in CVB3-infected cardiomyocytes, and SRT1720 and trichostatin A (TSA) pretreatment decreased Ac-p53 levels. After pifithrin-α pretreatment of CVB3-infected cardiomyocytes, the protein expression level of HDAC1 decreased while that of SIRT1 increased. Moreover, miR-34a expression and CVB3-induced apoptosis of cardiomyocytes were attenuated by pretreatment with SRT1720, TSA, or pifithrin-α, accompanied with Bax downregulation and Bcl-2 upregulation. In summary, these data indicate that miR-34a induces cardiomyocyte apoptosis by downregulating SIRT1, and the activation of the SIRT1-p53 pathway contributes to CVB3-induced apoptosis of cardiomyocytes. Thus, miR-34a might serve as a potential therapeutic target because it promotes cardiomyocyte apoptosis through the SIRT1-p53 signaling pathway.

Supplementation with psyllium seed husk reduces myocardial damage in a rat model of ischemia/reperfusion

BACKGROUND/OBJECTIVES

Myocardial infarction (MI) is caused by extensive myocardial damage attributed to the occlusion of coronary arteries. Our previous study in a rat model of ischemia/reperfusion (I/R) demonstrated that administration of arabinoxylan (AX), comprising arabinose and xylose, protects against myocardial injury. In this study, we undertook to investigate whether psyllium seed husk (PSH), a safe dietary fiber containing a high level of AX (> 50%), also imparts protection against myocardial injury in the same rat model.

MATERIALS/METHODS

Rats were fed diets supplemented with PSH (1, 10, or 100 mg/kg/d) for 3 d. The rats were then subjected to 30 min ischemia through ligation of the left anterior descending coronary artery, followed by 3 h reperfusion through release of the ligation. The hearts were harvested and cut into four slices. To assess infarct size (IS), an index representing heart damage, the slices were stained with 2,3,5-triphenyltetrazolium chloride (TTC). To elucidate underlying mechanisms, Western blotting was performed for the slices.

RESULTS

Supplementation with 10 or 100 mg/kg/d of PSH significantly reduces the IS. PSH supplementation (100 mg/kg/d) tends to reduce caspase-3 generation and increase BCL-2/BAX ratio. PSH supplementation also upregulates the expression of nuclear factor erythroid 2-related factor 2 (NRF2), and its target genes including antioxidant enzymes such as glutathione S-transferase mu 2 (GSTM2) and superoxide dismutase 2 (SOD2). PSH supplementation upregulates some sirtuins (NAD⁺-dependent deacetylases) including SIRT5 (a mitochondrial sirtuin) and SIRT6 and SIRT7 (nuclear sirtuins). Finally, PSH supplementation upregulates the expression of protein kinase A (PKA), and increases phosphorylated cAMP response element-binding protein (CREB) (pCREB), a target protein of PKA.

CONCLUSIONS

The results from this study indicate that PSH consumption reduces myocardial I/R injury in rats by inhibiting the apoptotic cascades through modulation of gene expression of several genes located upstream of apoptosis. Therefore, we believe that PSH can be developed as a functional food that would be beneficial in the prevention of MI.

Protection of the myocardium against ischemia/reperfusion injury by punicalagin through an SIRT1-NRF-2-HO-1-dependent mechanism

Punicalagin has been found to exert cardiac protective effects against myocardial ischemia/reperfusion (MI/R) injury, although the detailed mechanisms remain largely unknown. This experiment was performed to explore the potential involvement of silent information regulator 1 (SIRT1)-NFE2-related factor 2 (NRF-2)-heme oxygenase-1 (HO-1) pathway in the cardiac protective actions of punicalagin. Sprague-Dawley (SD) rats were subjected to MI/R operation with or without punicalagin treatment (40 mg kg^-1d^-1). We showed that punicalagin-treated group exhibited enhanced cardiac function, reduced myocardial infarction and decreased cleaved caspase-3 level. Furthermore, myocardial oxidative/nitrosative stress was ameliorated by punicalagin as evidenced by suppressed superoxide generation, gp91^phox and iNOS expressions, NO metabolites as well as myocardial nitrotyrosine level. Additionally, punicalagin decreased myocardial IL-6, TNF-α and the levels of ICAM-1, VCAM-1 and IKK-β expressions as well as IκB-α phosphorylation and NF-κB nuclear translocation. However, these effects were abolished by EX527 (5 mg kg^-1d^-1, a selective SIRT1 inhibitor). We further found that punicalagin dose-dependently enhanced SIRT1 nuclear distribution and NRF-2-HO-1 signaling. While EX527 treatment not only reduced SIRT1 activity, but also reversed the activation of NRF-2-HO-1 pathway. Collectively, these results revealed that punicalagin reduced cardiac oxidative/nitrosative stress and inflammatory response induced by MI/R operation through SIRT1-mediated activation of NRF-2-HO-1 signaling.

A Novel Substrate Radiotracer for Molecular Imaging of SIRT2 Expression and Activity with Positron Emission Tomography

PURPOSE

The purpose of this study was to develop a SIRT2-specific substrate-type radiotracer for non-invasive PET imaging of epigenetic regulatory processes mediated by SIRT2 in normal and disease tissues.

PROCEDURES

A library of compounds containing tert-butyloxycarbonyl-lysine-aminomethylcoumarin backbone was derivatized with fluoroalkyl chains 3-16 carbons in length. SIRT2 most efficiently cleaved the myristoyl, followed by 12-fluorododecanoic and 10-fluorodecanoic groups (K_cat/K_m 716.5 ± 72.8, 615.4 ± 50.5, 269.5 ± 52.1/s mol, respectively). Radiosynthesis of 12- [¹⁸F]fluorododecanoic aminohexanoicanilide (12-[¹⁸F]DDAHA) was achieved by nucleophilic radiofluorination of 12-iododecanoic-AHA precursor.

RESULTS

A significantly higher accumulation of 12-[¹⁸F]DDAHA was observed in MCF-7 and MDA-MB-435 cells in vitro as compared to U87, MiaPaCa, and MCF10A, which was consistent with levels of SIRT2 expression. Initial in vivo studies using 12-[¹⁸F]DDAHA conducted in a 9L glioma-bearing rats were discouraging, due to rapid defluorination of this radiotracer upon intravenous administration, as evidenced by significant accumulation of F-18 radioactivity in the skull and other bones, which confounded the interpretation of images of radiotracer accumulation within the tumor and other regions of the brain.

CONCLUSIONS

The next generation of SIRT2-specific radiotracers resistant to systemic defluorination should be developed using alternative sites of radiofluorination on the aliphatic chain of DDAHA. A SIRT2-selective radiotracer may provide information about SIRT2 expression and activity in tumors and normal organs and tissues, which may help to better understand the roles of SIRT2 in different diseases.

Effect of Sucrose Ingestion at the End of a Critical Window that Increases Hypertension Susceptibility on Peripheral Mechanisms Regulating Blood Pressure in Rats. Role of Sirtuins 1 and 3

Susceptibility to develop hypertension may be established during early stages of life that include the intrauterine period, infancy and childhood. We recently showed that blood pressure increased when rats reached adulthood when sucrose was ingested for a short-term critical window from postnatal day 12 to 28 in the rat, which corresponds to days around weaning. Here, we studied several factors that might participate in the increased susceptibility to hypertension when adulthood is reached by analyzing the changes produced at the end of the sucrose ingestion during this critical period. Body weight of the rats at the end of the sucrose period was decreased even if there was an increased ingestion in Kcal. We found an increase in blood pressure accompanied by a decrease in endothelial nitric oxide synthase (eNOS) expression in the aorta. When insulin was administered to rats receiving sucrose, glucose in plasma diminished later than in controls and this slight insulin resistance may reduce nitric oxide synthase action. Oleic acid that modulates eNOS expression was increased, lipoperoxidation was elevated and total non-enzymatic anti-oxidant capacity was decreased. There was also a decrease in SOD2 expression. We also studied the expression of Sirt1, which regulates eNOS expression and Sirt3, which regulates SOD2 expression as possible epigenetic targets of enzyme expression involved in the long- term programming of hypertension. Sirt3 was decreased but we did not find an alteration in Sirt1 expression. We conclude that these changes may underpin the epigenetic programming of increased susceptibility to develop hypertension in the adults when there was exposure to high sucrose levels near weaning in rats.

Role of Epigenomics in Bone and Cartilage Disease

Phenotypic variation in skeletal traits and diseases is the product of genetic and environmental factors. Epigenetic mechanisms include information-containing factors, other than DNA sequence, that cause stable changes in gene expression and are maintained during cell divisions. They represent a link between environmental influences, genome features, and the resulting phenotype. The main epigenetic factors are DNA methylation, posttranslational changes of histones, and higher-order chromatin structure. Sometimes non-coding RNAs, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), are also included in the broad term of epigenetic factors. There is rapidly expanding experimental evidence for a role of epigenetic factors in the differentiation of bone cells and the pathogenesis of skeletal disorders, such as osteoporosis and osteoarthritis. However, different from genetic factors, epigenetic signatures are cell- and tissue-specific and can change with time. Thus, elucidating their role has particular difficulties, especially in human studies. Nevertheless, epigenomewide association studies are beginning to disclose some disease-specific patterns that help to understand skeletal cell biology and may lead to development of new epigenetic-based biomarkers, as well as new drug targets useful for treating diffuse and localized disorders. Here we provide an overview and update of recent advances on the role of epigenomics in bone and cartilage diseases. © 2019 American Society for Bone and Mineral Research.

The Crosstalk between Acetylation and Phosphorylation: Emerging New Roles for HDAC Inhibitors in the Heart

Approximately five million United States (U.S.) adults are diagnosed with heart failure (HF), with eight million U.S. adults projected to suffer from HF by 2030. With five-year mortality rates following HF diagnosis approximating 50%, novel therapeutic treatments are needed for HF patients. Pre-clinical animal models of HF have highlighted histone deacetylase (HDAC) inhibitors as efficacious therapeutics that can stop and potentially reverse cardiac remodeling and dysfunction linked with HF development. HDACs remove acetyl groups from nucleosomal histones, altering DNA-histone protein electrostatic interactions in the regulation of gene expression. However, HDACs also remove acetyl groups from non-histone proteins in various tissues. Changes in histone and non-histone protein acetylation plays a key role in protein structure and function that can alter other post translational modifications (PTMs), including protein phosphorylation. Protein phosphorylation is a well described PTM that is important for cardiac signal transduction, protein activity and gene expression, yet the functional role for acetylation-phosphorylation cross-talk in the myocardium remains less clear. This review will focus on the regulation and function for acetylation-phosphorylation cross-talk in the heart, with a focus on the role for HDACs and HDAC inhibitors as regulators of acetyl-phosphorylation cross-talk in the control of cardiac function.

Mitochondrial regulation of cardiac aging

Aging is associated with progressive decline in cardiac structure and function. Accumulating evidence in model organisms and humans links cardiac aging to mitochondrial regulation, encompassing a complex interplay of mitochondrial morphology, mitochondrial ROS, mitochondrial DNA mutations, mitochondrial unfolded protein response, nicotinamide adenine dinucleotide levels and sirtuins, as well as mitophagy. This review summarizes the recent discoveries on the mitochondrial regulation of cardiac aging and the possible molecular mechanisms underlying the anti-aging effects, as well as the potential interventions that alleviate aging-related cardiac diseases and attenuate cardiac aging via the regulation of mitochondria.

Exogenous Hydrogen Sulfide Supplement Attenuates Isoproterenol-Induced Myocardial Hypertrophy in a Sirtuin 3-Dependent Manner

Hydrogen sulfide (H₂S) is a gasotransmitter with a variety of cardiovascular protective effects. Sirtuin 3 (SIRT3) is closely related to mitochondrial function and oxidative stress. We found that NaHS increased SIRT3 expression in the preventive effect on isoproterenol- (ISO-) induced myocardial hypertrophy. We further investigated whether exogenous H₂S supplement improved ISO-induced myocardial hypertrophy in a SIRT3-dependent manner. 10-week-old male 129S1/SvImJ (WT) mice and SIRT3 knockout (KO) mice were intraperitoneally injected with NaHS (50 μmol/kg/d) for two weeks and then intraperitoneally injected with ISO (60 mg/kg/d) for another two weeks. In WT mice, NaHS significantly reduced the cardiac index of ISO-induced mice, decreased the cross-sectional area of cardiomyocytes, and inhibited the expressions of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) mRNA. The activity of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) in the myocardium was increased, but the level of malondialdehyde (MDA) was decreased. The fluorescence intensity of dihydroethidium staining for superoxide anion was attenuated. Optic atrophy 1 (OPA1) expression was upregulated, while dynamin-related protein 1 (DRP1) expression was downregulated. ERK, but not P38 and JNK, phosphorylation was downregulated. However, all above protective effects were unavailable in ISO-induced SIRT3 KO mice. Our present study suggested that exogenous H₂S supplement inhibited ISO-induced cardiac hypertrophy depending on SIRT3, which might be associated with antioxidant stress.