SIRT1 deacetylates the cardiac transcription factor Nkx2.5 and inhibits its transcriptional activity

Roles of Sirtuins in Cardiovascular Diseases: Mechanisms and Therapeutics

Cardiovascular diseases (CVDs) are experiencing a rapid surge and are widely recognized as the leading cause of mortality in the current aging society. Given the multifactorial etiology of CVDs, understanding the intricate molecular and cellular mechanisms is imperative. Over the past 2 decades, many scientists have focused on Sirtuins, a family of nicotinamide adenine dinucleotide-dependent deacylases. Sirtuins are highly conserved across species, from yeasts to primates, and play a crucial role in linking aging and diseases. Sirtuins participate in nearly all key physiological and pathological processes, ranging from embryogenic development to stress response and aging. Abnormal expression and activity of Sirtuins exist in many aging-related diseases, while their activation has shown efficacy in mitigating these diseases (eg, CVDs). In terms of research, this field has maintained fast, sustained growth in recent years, from fundamental studies to clinical trials. In this review, we present a comprehensive, up-to-date discussion on the biological functions of Sirtuins and their roles in regulating cardiovascular biology and CVDs. Furthermore, we highlight the latest advancements in utilizing Sirtuin-activating compounds and nicotinamide adenine dinucleotide boosters as potential pharmacological targets for preventing and treating CVDs. The key unresolved issues in the field-from the chemicobiological regulation of Sirtuins to Sirtuin-targeted CVD investigations-are also discussed. This timely review could be critical in understanding the updated knowledge of Sirtuin biology in CVDs and facilitating the clinical accessibility of Sirtuin-targeting interventions.

Atrial natriuretic peptide signaling co-regulates lipid metabolism and ventricular conduction system gene expression in the embryonic heart

It has been shown that atrial natriuretic peptide (ANP) and its high affinity receptor (NPRA) are involved in the formation of ventricular conduction system (VCS). Inherited genetic variants in fatty acid oxidation (FAO) genes are known to cause conduction abnormalities in newborn children. Although the effect of ANP on energy metabolism in noncardiac cell types is well documented, the role of lipid metabolism in VCS cell differentiation via ANP/NPRA signaling is not known. In this study, histological sections and primary cultures obtained from E11.5 mouse ventricles were analyzed to determine the role of metabolic adaptations in VCS cell fate determination and maturation. Exogenous treatment of E11.5 ventricular cells with ANP revealed a significant increase in lipid droplet accumulation, FAO and higher expression of VCS marker Cx40. Using specific inhibitors, we further identified PPARγ and FAO as critical downstream regulators of ANP-mediated regulation of metabolism and VCS formation.

The transcription factor GATA6 accelerates vascular smooth muscle cell senescence-related arterial calcification by counteracting the role of anti-aging factor SIRT6 and impeding DNA damage repair

Arterial calcification is a hallmark of vascular pathology in the elderly and in individuals with chronic kidney disease (CKD). Vascular smooth muscle cells (VSMCs), after attaining a senescent phenotype, are implicated in the calcifying process. However, the underlying mechanism remains to be elucidated. Here, we reveal an aberrant upregulation of transcriptional factor GATA6 in the calcified aortas of humans, mice with CKD and mice subjected to vitamin D3 injection. Knockdown of GATA6, via recombinant adeno-associated virus carrying GATA6 shRNA, inhibited the development of arterial calcification in mice with CKD. Further gain- and loss-of function experiments in vitro verified the contribution of GATA6 in osteogenic differentiation of VSMCs. Samples of human aorta exhibited a positive relationship between age and GATA6 expression and GATA6 was also elevated in the aortas of old as compared to young mice. Calcified aortas displayed senescent features with VSMCs undergoing premature senescence, blunted by GATA6 downregulation. Notably, abnormal induction of GATA6 in senescent and calcified aortas was rescued in Sirtuin 6 (SIRT6)-transgenic mice, a well-established longevity mouse model. Suppression of GATA6 accounted for the favorable effect of SIRT6 on VSMCs senescence prevention. Mechanistically, SIRT6 inhibited the transcription of GATA6 by deacetylation and increased degradation of transcription factor Nkx2.5. Moreover, GATA6 was induced by DNA damage stress during arterial calcification and subsequently impeded the Ataxia-telangiectasia mutated (ATM)-mediated DNA damage repair process, leading to accelerated VSMCs senescence and osteogenic differentiation. Thus, GATA6 is a novel regulator in VSMCs senescence. Our findings provide novel insight in arterial calcification and a potential new target for intervention.

Tmem88 confines ectodermal Wnt2bb signaling in pharyngeal arch artery progenitors for balancing cell cycle progression and cell fate decision

Pharyngeal arch artery (PAA) progenitors undergo proliferative expansion and angioblast differentiation to build vessels connecting the heart with the dorsal aortae. However, it remains unclear whether and how these two processes are orchestrated. Here we demonstrate that Tmem88 is required to fine-tune PAA progenitor proliferation and differentiation. Loss of zebrafish tmem88a/b leads to an excessive expansion and a failure of differentiation of PAA progenitors. Moreover, tmem88a/b deficiency enhances cyclin D1 expression in PAA progenitors via aberrant Wnt signal activation. Mechanistically, cyclin D1-CDK4/6 promotes progenitor proliferation through accelerating the G1/S transition while suppressing angioblast differentiation by phosphorylating Nkx2.5/Smad3. Ectodermal Wnt2bb signaling is confined by Tmem88 in PAA progenitors to ensure a balance between proliferation and differentiation. Therefore, the proliferation and angioblast differentiation of PAA progenitors manifest an inverse relationship and are delicately regulated by cell cycle machinery downstream of the Tmem88-Wnt pathway.

SIRT6 in Vascular Diseases, from Bench to Bedside

Aging is a key risk factor for angiogenic dysfunction and cardiovascular diseases, including heart failure, hypertension, atherosclerosis, diabetes, and stroke. Members of the NAD+-dependent class III histone deacetylase family, sirtuins, are conserved regulators of aging and cardiovascular and cerebrovascular diseases. The sirtuin SIRT6 is predominantly located in the nucleus and shows deacetylase activity for acetylated histone 3 lysine 56 and lysine 9 as well as for some non-histone proteins. Over the past decade, experimental analyses in rodents and non-human primates have demonstrated the critical role of SIRT6 in extending lifespan. Recent studies highlighted the pleiotropic protective actions of SIRT6 in angiogenesis and cardiovascular diseases, including atherosclerosis, hypertension, heart failure, and stroke. Mechanistically, SIRT6 participates in vascular diseases via epigenetic regulation of endothelial cells, vascular smooth muscle cells, and immune cells. Importantly, SIRT6 activators (e.g., MDL-800/MDL-811) have provided therapeutic value for treating age-related vascular disorders. Here, we summarized the roles of sirtuins in cardiovascular diseases; reviewed recent advances in the understanding of SIRT6 in vascular biology, cardiovascular aging, and diseases; highlighted its therapeutic potential; and discussed future perspectives.

miR-146a impedes the anti-aging effect of AMPK via NAMPT suppression and NAD+/SIRT inactivation

Nicotinamide adenine dinucleotide (NAD⁺) is indispensable for the anti-aging activity of the sirtuin (SIRT) family enzymes. AMP-activated protein kinase (AMPK) upregulates NAD⁺ synthesis and SIRT activity in a nicotinamide phosphoribosyltransferase (NAMPT)-dependent manner. However, the molecular mechanisms that affect AMPK-driven NAMPT expression and NAD⁺/SIRT activation remain unclear. In this study, we tried to identify senescence-associated microRNAs (miRNAs) that negatively regulate the cascade linking AMPK and NAMPT expression. miRNA-screening experiments showed that the expression of miR-146a increased in senescent cells but decreased following AMPK activation. Additionally, miR-146a overexpression weakened the metformin-mediated upregulation of NAMPT expression, NAD⁺ synthesis, SIRT activity, and senescence protection, whereas treatment with the miR-146a inhibitor reversed this effect. Importantly, these findings were observed both in vitro and in vivo. Mechanistically, miR-146a directly targeted the 3′-UTR of Nampt mRNA to reduce the expression of NAMPT. AMPK activators metformin and 5-aminoimidazole-4-carboxamide (AICAR) hindered miR-146a expression at the transcriptional level by promoting IκB kinase (IKK) phosphorylation to attenuate nuclear factor-kappaB (NF-κB) activity. These findings identified a novel cascade that negatively regulates the NAD⁺/SIRT pathway by suppressing miR-146a-mediated NAMPT downregulation. Furthermore, our results showed that miR-146a impedes the anti-aging effect of AMPK. This mutual inhibitory relationship between miR-146a and AMPK enriches our understanding of the molecular connections between AMPK and SIRT and provides new insight into miRNA-mediated NAD⁺/SIRT regulation and an intervention point for the prevention of aging and age-related diseases.

Sirtuin Family and Diabetic Kidney Disease

Diabetes mellitus (DM) is gradually attacking the health and life of people all over the world. Diabetic kidney disease (DKD) is one of the most common chronic microvascular complications of DM, whose mechanism is complex and still lacks research. Sirtuin family is a class III histone deacetylase with highly conserved NAD⁺ binding domain and catalytic functional domain, while different N-terminal and C-terminal structures enable them to bind different deacetylated substrates to participate in the cellular NAD⁺ metabolism. The kidney is an organ rich in NAD⁺ and database exploration of literature shows that the Sirtuin family has different expression localization in renal, cellular, and subcellular structures. With the progress of modern technology, a variety of animal models and reagents for the Sirtuin family and DKD emerged. Machine learning in the literature shows that the Sirtuin family can regulate pathophysiological injury mainly in the glomerular filtration membrane, renal tubular absorption, and immune inflammation through various mechanisms such as epigenetics, multiple signaling pathways, and mitochondrial function. These mechanisms are the key nodes participating in DKD. Thus, it is of great significance for target therapy to study biological functions of the Sirtuin family and DKD regulation mechanism in-depth.

Indoleamine 2,3-Dioxygenase 1 (IDO1) Promotes Cardiac Hypertrophy via a PI3K-AKT-mTOR-Dependent Mechanism

Indoleamine 2,3-dioxygenase 1 (IDO1) is an enzyme for tryptophan metabolism, involved in immune cell differentiation/maturation and cancer biology. IDO1 is also expressed in cardiomyocytes, but its roles in the cardiovascular system are not fully understood. Here, we reported the functions of IDO1 during cardiac hypertrophy. Quantitative real-time PCR and Western blot experiments demonstrated the upregulation of IDO1 mRNA and protein levels in human and hypertrophic mouse hearts, as well as in angiotensin II (Ang II)-induced hypertrophic rat cardiomyocytes. IDO1 activity and metabolite product kynurenine were upregulated in rodent hypertrophic hearts and cardiomyocytes. Inhibition of IDO1 activity with PF-06840003 reduced Ang II-induced cardiac hypertrophy and rescued cardiac function in mice. siRNA-mediated knockdown of Ido1 repressed Ang II-induced growth in cardiomyocyte size and overexpression of hypertrophy-associated genes atrial natriuretic peptide (Anp or Nppa), brain natriuretic peptide (Bnp or Nppb), β-myosin heavy chain (β-Mhc or Myh7). By contrast, adenovirus-mediated rat Ido1 overexpression in cardiomyocytes promoted hypertrophic growth induced by Ang II. Mechanism analysis showed that IDO1 overexpression was associated with PI3K-AKT-mTOR signaling to activate the ribosomal protein S6 kinase 1 (S6K1), which promoted protein synthesis in Ang II-induced hypertrophy of rat cardiomyocytes. Finally, we provided evidence that inhibition of PI3K with pictilisib, AKT with perifosine, or mTOR with rapamycin, blocked the effects of IDO1 on protein synthesis and cardiomyocyte hypertrophy in Ang II-treated cells. Collectively, our findings identify that IDO1 promotes cardiomyocyte hypertrophy partially via PI3K-AKT-mTOR-S6K1 signaling.

PHD Finger Protein 19 Promotes Cardiac Hypertrophy via Epigenetically Regulating SIRT2

Epigenetic regulations essentially participate in the development of cardiomyocyte hypertrophy. PHD finger protein 19 (PHF19) is a polycomb protein that controls H3K36me3 and H3K27me3. However, the roles of PHF19 in cardiac hypertrophy remain unknown. Here in this work, we observed that PHF19 promoted cardiac hypertrophy via epigenetically targeting SIRT2. In angiotensin II (Ang II)-induced cardiomyocyte hypertrophy, adenovirus-mediated knockdown of Phf19 reduced the increase in cardiomyocyte size, repressed the expression of hypertrophic marker genes Anp and Bnp, as well as inhibited protein synthesis. By contrast, Phf19 overexpression promoted Ang II-induced cardiomyocyte hypertrophy in vitro. We also knocked down Phf19 expression in mouse hearts in vivo. The results demonstrated that Phf19 knockdown reduced Ang II-induced decline in cardiac fraction shortening and ejection fraction. Phf19 knockdown also inhibited Ang II-mediated increase in heart weight, reduced cardiomyocyte size, and repressed the expression of hypertrophic marker genes in mouse hearts. Further mechanism studies showed that PHF19 suppressed the expression of SIRT2, which contributed to the function of PHF19 during cardiomyocyte hypertrophy. PHF19 bound the promoter of SIRT2 and regulated the balance between H3K27me3 and H3K36me3 to repress the expression of SIRT2 in vitro and in vivo. In human hypertrophic hearts, the overexpression of PHF19 and downregulation of SIRT2 were observed. Of importance, PHF19 expression was positively correlated with hypertrophic marker genes ANP and BNP but negatively correlated with SIRT2 in human hypertrophic hearts. Therefore, our findings demonstrated that PHF19 promoted the development of cardiac hypertrophy via epigenetically regulating SIRT2.

DNAJC12 promotes lung cancer growth by regulating the activation of β‑catenin

Lung cancer has become the leading cause of cancer‑associated mortality worldwide. However, the underlying mechanisms of lung cancer remain poorly understood. DnaJ heat shock protein family (HSP40) member C12 (DNAJC12) is a type III member belonging to the HSP40/DNAJ family. The role of DNAJC12 in numerous types of cancer has been previously reported; however, the effect of DNAJC12 in lung cancer remains unknown. The results of the present study indicated that DNAJC12 may be involved in lung cancer proliferation and migration by regulating the β‑catenin signaling pathway. Data generated in the present study and from The Cancer Genome Atlas revealed that the DNAJC12 expression levels were significantly upregulated in lung cancer tissues compared with non‑cancer lung tissues. The expression of DNAJC12 was subsequently knocked down in A549 and NCI‑H1975 lung cancer cells using lentiviral transfections and further experiments demonstrated that the knockdown of DNAJC12 inhibited the proliferation, colony formation, migration and invasion of lung cancer cells. The results of flow cytometric assays also revealed that the knockdown of DNAJC12 induced the apoptosis of lung cancer cells. In addition, the effects of DNAJC12 knockdown on the in vivo growth of lung cancer cells were observed. Signaling pathway analysis revealed that the knockdown of DNAJC12 expression suppressed the phosphorylation of p65 NF‑κB, downregulated the expression levels and inhibited the subsequent activation of β‑catenin, and downregulated the expression levels of vimentin. Rescue experiments demonstrated that the overexpression of β‑catenin, but not that of NF‑κB or vimentin, reversed the effects of DNAJC12 knockdown on the proliferation and invasion of lung cancer cells. On the whole, the findings of the present study suggest that DNAJC12 may play a crucial role in lung cancer tumorigenesis by regulating the expression and activation of β‑catenin. Therefore, DNAJC12 may represent a novel target for the treatment of lung cancer.

KLK11 promotes the activation of mTOR and protein synthesis to facilitate cardiac hypertrophy

BACKGROUND

Cardiovascular diseases have become the leading cause of death worldwide, and cardiac hypertrophy is the core mechanism underlying cardiac defect and heart failure. However, the underlying mechanisms of cardiac hypertrophy are not fully understood. Here we investigated the roles of Kallikrein 11 (KLK11) in cardiac hypertrophy.

METHODS

Human and mouse hypertrophic heart tissues were used to determine the expression of KLK11 with quantitative real-time PCR and western blot. Mouse cardiac hypertrophy was induced by transverse aortic constriction (TAC), and cardiomyocyte hypertrophy was induced by angiotensin II. Cardiac function was analyzed by echocardiography. The signaling pathway was analyzed by western blot. Protein synthesis was monitored by the incorporation of [3H]-leucine. Gene expression was analyzed by quantitative real-time PCR.

RESULTS

The mRNA and protein levels of KLK11 were upregulated in human hypertrophic hearts. We also induced cardiac hypertrophy in mice and observed the upregulation of KLK11 in hypertrophic hearts. Our in vitro experiments demonstrated that KLK11 overexpression promoted whereas KLK11 knockdown repressed cardiomyocytes hypertrophy induced by angiotensin II, as evidenced by cardiomyocyte size and the expression of hypertrophy-related fetal genes. Besides, we knocked down KLK11 expression in mouse hearts with adeno-associated virus 9. Knockdown of KLK11 in mouse hearts inhibited TAC-induced decline in fraction shortening and ejection fraction, reduced the increase in heart weight, cardiomyocyte size, and expression of hypertrophic fetal genes. We also observed that KLK11 promoted protein synthesis, the key feature of cardiomyocyte hypertrophy, by regulating the pivotal machines S6K1 and 4EBP1. Mechanism study demonstrated that KLK11 promoted the activation of AKT-mTOR signaling to promote S6K1 and 4EBP1 pathway and protein synthesis. Repression of mTOR with rapamycin blocked the effects of KLK11 on S6K1 and 4EBP1 as well as protein synthesis. Besides, rapamycin treatment blocked the roles of KLK11 in the regulation of cardiomyocyte hypertrophy.

CONCLUSIONS

Our findings demonstrated that KLK11 promoted cardiomyocyte hypertrophy by activating AKT-mTOR signaling to promote protein synthesis.

GPR39 promotes cardiac hypertrophy by regulating the AMPK-mTOR pathway and protein synthesis

Hypertrophic growth of the cardiomyocytes is one of the core mechanisms underlying cardiac hypertrophy. However, the mechanism underlying cardiac hypertrophy remains not fully understood. Here we provided evidence that G protein-coupled receptor 39 (GPR39) promotes cardiac hypertrophy via inhibiting AMP-activated protein kinase (AMPK) signaling. GRP39 expression is overexpressed in hypertrophic hearts of humans and transverse aortic constriction (TAC)-induced cardiac hypertrophy in mice. In neonatal cardiomyocytes, adenovirus-mediated overexpression of GPR39 promoted angiotensin II-induced cardiac hypertrophy, while GPR39 knockdown repressed hypertrophic response. Adeno-associated virus 9-mediated knockdown of GPR39 suppressed TAC-induced decline in fraction shortening and ejection fraction, increase in heart weight and cardiomyocyte size, as well as overexpression of hypertrophic fetal genes. A mechanism study demonstrated that GPR39 repressed the activation of AMPK to activate the mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase β-1 (S6K1), subsequently promoted de novo protein synthesis. Inhibition of mTOR with rapamycin blocked the effects of GPR39 overexpression on protein synthesis and repressed cardiac hypertrophy. Collectively, our findings demonstrated that GPR39 promoted cardiac hypertrophy via regulating the AMPK-mTOR-S6K1 signaling pathway, and GRP39 can be targeted for the treatment of cardiac hypertrophy.

SIRT1 Inhibits High Shear Stress-Induced Apoptosis in Rat Cortical Neurons

INTRODUCTION

Sirtuin1 (SIRT1), one of NAD+-dependent protein deacetylases, is proved to be neuroprotective in aging diseases, but its effect on neuronal apoptosis has not been clarified. To investigate the role of SIRT1 in inhibiting neuronal apoptosis, SIRT1 was interfered or overexpressed in cortical neurons.

METHODS

We exerted overloading laminar shear stress with 10 dyn/cm2 for 4, 8, and 12 h on neurons to cause cortical neuronal apoptosis, and the apoptosis percentage was tested by TUNEL assay. The adenovirus plasmids containing SIRT1 RNA interference or SIRT1 wild type gene were transfected into neurons before shear stress loading. SIRT1 mRNA and protein level were tested by Real-time PCR, immunofluorescence and western blots assay.

RESULTS

SIRT1 was primarily expressed in nucleus of cortical neurons, and its mRNA level was significantly increased after 4 h stimulation. SIRT1 RNAi cortical neurons had higher TUNEL positive cells, while SIRT1 overexpression significantly decreased the percentage of died cells induced by shear stress compared to control group.

CONCLUSIONS

SIRT1 plays a neuroprotective role in shear stress induced apoptosis and could be as potential pharmacological targets against neuronal degeneration in future.

HTR2A promotes the development of cardiac hypertrophy by activating PI3K-PDK1-AKT-mTOR signaling

5-Hydroxytryptamine receptor 2A (HTR2A) is a central regulator of fetal brain development and cognitive function in adults. However, the roles of HTR2A in the cardiovascular system are not fully understood. Here in this study, we explored the function of HTR2A in cardiac hypertrophy. Significantly, the expression levels of HTR2A mRNA and protein levels were upregulated in hypertrophic hearts of human patients. Besides, the expression of HTR2A was also upregulated in isoproterenol (ISO)-induced cardiac hypertrophy in the mouse. Next, the expression of HTR2A was knocked down with shRNA or overexpressed with adenovirus in neonatal rat cardiomyocytes, and ISO was used to induce cardiomyocyte hypertrophy. We showed that HTR2A knockdown repressed ISO-induced cardiomyocyte hypertrophy, which was demonstrated by decreased cardiomyocyte size and repressed expression of hypertrophic fetal genes (e.g., myosin heavy chain beta (β-Mhc), atrial natriuretic peptide (Anp), and brain natriuretic peptide (Bnp)). By contrast, HTR2A overexpression promoted cardiomyocyte hypertrophy. Of note, we observed that HTR2A promoted the activation (phosphorylation) of AKT-mTOR (mammalian target of rapamycin) signaling in cardiomyocytes, and repression of AKT-mTOR with perifosine or rapamycin blocked the effects of HTR2A on cardiomyocyte hypertrophy. Finally, we showed that HTR2A regulated AKT-mTOR signaling through activating the PI3K-PDK1 pathway, and inhibition of either PI3K or PDK1 blocked the roles of HTR2A in regulating AKT-mTOR signaling and cardiomyocyte hypertrophy. Altogether, these findings demonstrated that HTR2A activated PI3K-PDK1-AKT-mTOR signaling and promoted cardiac hypertrophy.

Divergent Transcription of the Nkx2-5 Locus Generates Two Enhancer RNAs with Opposing Functions

Enhancer RNAs (eRNAs) are a subset of long noncoding RNA generated from genomic enhancers: they are thought to act as potent promoters of the expression of nearby genes through interaction with the transcriptional and epigenomic machineries. In the present work, we describe two eRNAs transcribed from the enhancer of Nkx2-5—a gene specifying a master cardiomyogenic lineage transcription factor (TF)—which we call Intergenic Regulatory Element Nkx2-5 Enhancers (IRENEs). The IRENEs are encoded, respectively, on the same strand (SS) and in the divergent direction (div) respect to the nearby gene. Of note, these two eRNAs have opposing roles in the regulation of Nkx2-5: IRENE-SS acts as a canonical promoter of transcription, whereas IRENE-div represses the activity of the enhancer through recruitment of the histone deacetylase sirtuin 1. Thus, we have identified an autoregulatory loop controlling expression of the master cardiac TF NKX2-5, in which one eRNA represses transcription.

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Two eRNAs (IRENE-SS, IRENE-div) with opposing functions are found upstream of Nkx2-5

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IRENE-SS works as a classical eRNA, acting as a transcriptional activator

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IRENE-div acts unconventionally, functioning as a transcriptional repressor

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IRENEs epigenetically control enhancer status and, subsequently, locus architecture

The Histone Demethylase JMJD1C Regulates CAMKK2-AMPK Signaling to Participate in Cardiac Hypertrophy

The roles of the histone demethylase JMJD1C in cardiac hypertrophy remain unknown. JMJD1C was overexpressed in hypertrophic hearts of humans and mice, whereas the histone methylation was reduced. Jmjd1c knockdown repressed the angiotensin II (Ang II)-mediated increase in cardiomyocyte size and overexpression of hypertrophic genes in cardiomyocytes. By contrast, JMJD1C overexpression promoted the hypertrophic response of cardiomyocytes. Our further molecular mechanism study revealed that JMJD1C regulated AMP-dependent kinase (AMPK) in cardiomyocytes. JMJD1C did not influence LKB1 but repressed Camkk2 expression in cardiomyocytes. Inhibition of CAMKK2 with STO609 blocked the effects of JMJD1C on AMPK. AMPK knockdown blocked the inhibitory functions of JMJD1C knockdown on Ang II-induced hypertrophic response, whereas metformin reduced the functions of JMJD1C and repressed the hypertrophic response in cardiomyocytes.

Usefulness of resveratrol supplementation in decreasing cardiometabolic risk factors comparing subjects with metabolic syndrome and healthy subjects with or without obesity: meta-analysis using multinational, randomised, controlled trials

Introduction

Resveratrol (RES), a natural polyphenolic compound, has been linked to some beneficial effects against cardiovascular disease (CVD).

Material and methods

We conducted a systematic search to conduct a meta-analysis on cardiometabolic risk factors modulated by RES targeting patients with metabolic syndrome (Met-S) and Obese/Healthy (O/H) subjects. The PICO (Patient, Intervention, Comparison, Outcome) research question was: Does RES among patients with Met-S and O/H subjects reduce the cardiometabolic risk? The first group was affected with MetS, which is defined as a clustering of abdominal obesity, dyslipidaemia, hyperglycaemia, and hypertension in a single individual. The second group was composed of 'obese/healthy' individuals, i.e. healthy subjects with or without obesity. We performed a literature search of MEDLINE/ PubMed, Scopus, and Google Scholar for randomised, controlled trials (RCT) that estimated the effects of RES on cardiometabolic risk factors.

Results

We found 780 articles, of which 63 original articles and reviews were identified. Data from 17 well-conducted RCT studies, comprising 651 subjects, were extracted for analysis. Overall, RES had a significant influence on Homeostatic Model Assessment-Insulin Resistance (HOMA-IR), resulting in a mean difference of -0.520665 (95% CI: -1.12791; -0.01439; p = 0.00113). In Met-S, RES significantly reduced glucose, low-density lipoprotein-cholesterol (LDL-C), and total cholesterol (T-Chol) as detected by the mean difference of -1.069 (95% CI: -2.107, -0.032; p = 0.043), -0.924 (95% CI: -1.804, -0.043; p = 0.040), and -1.246 (95% CI: -2.314, -0.178; p = 0.022), respectively.

Conclusions

Despite some heterogeneity in the populations, RES supplementation seems to improve cardiometabolic health, decreasing some risk factors (HOMA-IR, LDL-C, and T-Chol) associated with CVD.

Carboxypeptidase A4 promotes cardiomyocyte hypertrophy through activating PI3K-AKT-mTOR signaling

Carboxypeptidase A4 (CPA4) is a member of the metallocarboxypeptidase family. Current studies have identified the roles of CPA4 in cancer biology and insulin sensitivity. However, the roles of CPA4 in other diseases are not known. In the present study, we investigated the roles of CPA4 in cardiac hypertrophy. The expression of CPA4 was significantly increased in the hypertrophic heart tissues of human patients and isoproterenol (ISO)-induced hypertrophic heart tissues of mice. We next knocked down Cpa4 with shRNA or overexpressed Cpa4 using adenovirus in neonatal rat cardiomyocytes and induced cardiomyocyte hypertrophy with ISO. We observed that Cpa4 overexpression promoted whereas Cpa4 knockdown reduced ISO-induced growth of cardiomyocyte size and overexpression of hypertrophy marker genes, such as myosin heavy chain β (β-Mhc), atrial natriuretic peptide (Anp), and brain natriuretic peptide (Bnp). Our further mechanism study revealed that the mammalian target of rapamycin (mTOR) signaling was activated by Cpa4 in cardiomyocytes, which depended on the phosphoinositide 3-kinase (PI3K)-AKT signaling. Besides, we showed that the PI3K-AKT-mTOR signaling was critically involved in the roles of Cpa4 during cardiomyocyte hypertrophy. Collectively, these results demonstrated that CPA4 is a regulator of cardiac hypertrophy by activating the PI3K-AKT-mTOR signaling, and CPA4 may serve as a promising target for the treatment of hypertrophic cardiac diseases.

An update on genetic variants of the NKX2-5

NKX2-5 is a homeodomain transcription factor that plays a crucial role in heart development. It is the first gene where a single genetic variant (GV) was found to be associated with congenital heart diseases in humans. In this study, we carried out a comprehensive survey of NKX2-5 GVs to build a unified, curated, and updated compilation of all available GVs. We retrieved a total of 1,380 unique GVs. From these, 970 had information on their frequency in the general population and 143 have been linked to pathogenic phenotypes in humans. In vitro effect was ascertained for 38 GVs. The homeodomain had the biggest cluster of pathogenic variants in the protein: 49 GVs in 60 residues, 23 in its third α-helix, where 11 missense variants may affect protein-DNA interaction or the hydrophobic core. We also pinpointed the likely location of pathogenic GVs in four linear motifs. These analyses allowed us to assign a putative explanation for the effect of 90 GVs. This study pointed to reliable pathogenicity for GVs in helix 3 of the homeodomain and may broaden the scope of functional and structural studies that can be done to better understand the effect of GVs in NKX2-5 function.

JMJD1A Represses the Development of Cardiomyocyte Hypertrophy by Regulating the Expression of Catalase

The histone demethylase JMJD family is involved in various physiological and pathological functions. However, the roles of JMJD1A in the cardiovascular system remain unknown. Here, we studied the function of JMJD1A in cardiac hypertrophy. The mRNA and protein levels of JMJD1A were significantly downregulated in the hearts of human patients with hypertrophic cardiomyopathy and the hearts of C57BL/6 mice underwent cardiac hypertrophy induced by transverse aortic constriction (TAC) surgery or isoproterenol (ISO) infusion. In neonatal rat cardiomyocytes (NRCMs), siRNA-mediated JMJD1A knockdown facilitated ISO or angiotensin II-induced increase in cardiomyocyte size, protein synthesis, and expression of hypertrophic fetal genes, including atrial natriuretic peptide (Anp), brain natriuretic peptide (Bnp), and Myh7. By contrast, overexpression of JMJD1A with adenovirus repressed the development of ISO-induced cardiomyocyte hypertrophy. We observed that JMJD1A reduced the production of total cellular and mitochondrial levels of reactive oxygen species (ROS), which was critically involved in the effects of JMJD1A because either N-acetylcysteine or MitoTEMPO treatment blocked the effects of JMJD1A deficiency on cardiomyocyte hypertrophy. Mechanism study demonstrated that JMJD1A promoted the expression and activity of Catalase under basal condition or oxidative stress. siRNA-mediated loss of Catalase blocked the protection of JMJD1A overexpression against ISO-induced cardiomyocyte hypertrophy. These findings demonstrated that JMJD1A loss promoted cardiomyocyte hypertrophy in a Catalase and ROS-dependent manner.

FBXW7 promotes pathological cardiac hypertrophy by targeting EZH2-SIX1 signaling

F-box and WD repeat domain-containing 7 (FBXW7) is an E3-ubiquitin ligase, which serves as one of the components of the SKP1, CUL1, and F-box protein type ubiquitin ligase (SCF) complex. Previous studies reveal that FBXW7 participates in cancer, inflammation and Parkinson's disease. FBXW7 also contributes to angiogenesis of endothelial cells. However, the function of FBXW7 in cardiac homeostasis remains to elucidate. Here we identified the critical role of FBXW7 during cardiac hypertrophy in humans and rodents. Quantitative real-time PCR (qRT-PCR) and Western blot revealed that the mRNA and protein levels of FBXW7 were upregulated significantly in hypertrophic hearts in human and mouse as well as Angiotensin II (Ang II)-induced hypertrophic neonatal rat cardiomyocytes (NRCM). Gain-of-function (adenovirus) and loss-of-function (siRNA) experiments provided evidence that FBXW7 promoted Ang II-induced cardiomyocyte hypertrophy as demonstrated by the increase in the size of cardiomyocytes and overexpression of hypertrophic fetal genes myosin heavy chain 7 (Myh7) natriuretic peptide a (Nppa), brain natriuretic peptide (Nppb). Further mechanism study revealed that FBXW7 promoted the expression of sine oculis homeobox homolog 1 (SIX1) in cardiomyocytes, which relied on regulation of the stability of the histone methyltransferase EZH2 (Enhancer of zeste homolog 2). Previous work revealed the pro-hypertrophic role of the EZH2-SIX1 axis in rodents. Indeed, our genetic and pharmacological evidence showed that the EZH2-SIX1 signaling was critically involved in FBXW7 functions in Ang II-induced cardiomyocyte hypertrophy. Therefore, we identified FBWX7 as an important regulator of cardiac hypertrophy via modulating the EZH2-SIX1 axis.

Alterations of Transcription of Genes Coding Anti-oxidative and Mitochondria-Related Proteins in Amyloid β Toxicity: Relevance to Alzheimer's Disease

A growing body of evidence indicates that pathological forms of amyloid beta (Aβ) peptide contribute to neuronal degeneration and synaptic loss in Alzheimer's disease (AD). In this study, we investigated the impact of exogenous Aβ1-42 oligomers (AβO) and endogenously liberated Aβ peptides on transcription of genes for anti-oxidative and mitochondria-related proteins in cell lines (neuronal SH-SY5Y and microglial BV2) and in brain cortex of transgenic AD (Tg-AD) mice, respectively. Our results demonstrated significant AβO-evoked changes in transcription of genes in SH-SY5Y cells, where AβO enhanced expression of Sod1, Cat, mt-Nd1, Bcl2, and attenuated Sirt5, Sod2 and Sdha. In BV2 line, AβO increased the level of mRNA for Sod2, Dnm1l, Bcl2, and decreased for Gpx4, Sirt1, Sirt3, mt-Nd1, Sdha and Mfn2. Then, AβO enhanced free radicals level and impaired mitochondrial membrane potential only in SH-SY5Y cells, but reduced viability of both cell types. Inhibitor of poly(ADP-ribose)polymerase-1 and activator of sirtuin-1 more efficiently enhanced viability of SH-SY5Y than BV2 affected by AβO. Analysis of brain cortex of Tg-AD mice confirmed significant downregulation of Sirt1, Mfn1 and mt-Nd1 and upregulation of Dnm1l. In human AD brain, changes of microRNA pattern (miRNA-9, miRNA-34a, miRNA-146a and miRNA-155) seem to be responsible for decrease in Sirt1 expression. Overall, our results demonstrated a diverse response of neuronal and microglial cells to AβO toxicity. Alterations of genes encoding Sirt1, Mfn1 and Drp1 in an experimental model of AD suggest that modulation of mitochondria dynamics and Sirt1, including miRNA strategy, may be crucial for improvement of AD therapy.

Cardiomyocyte Senescence and Cellular Communications Within Myocardial Microenvironments

Cardiovascular diseases have become the leading cause of human death. Aging is an independent risk factor for cardiovascular diseases. Cardiac aging is associated with maladaptation of cellular metabolism, dysfunction (or senescence) of cardiomyocytes, a decrease in angiogenesis, and an increase in tissue scarring (fibrosis). These events eventually lead to cardiac remodeling and failure. Senescent cardiomyocytes show the hallmarks of DNA damage, endoplasmic reticulum stress, mitochondria dysfunction, contractile dysfunction, hypertrophic growth, and senescence-associated secreting phenotype (SASP). Metabolism within cardiomyocytes is essential not only to fuel the pump function of the heart but also to maintain the functional homeostasis and participate in the senescence of cardiomyocytes. The senescence of cardiomyocyte is also regulated by the non-myocytes (endothelial cells, fibroblasts, and immune cells) in the local microenvironment. On the other hand, the senescent cardiomyocytes alter their phenotypes and subsequently affect the non-myocytes in the local microenvironment and contribute to cardiac aging and pathological remodeling. In this review, we first summarized the hallmarks of the senescence of cardiomyocytes. Then, we discussed the metabolic switch within senescent cardiomyocytes and provided a discussion of the cellular communications between dysfunctional cardiomyocytes and non-myocytes in the local microenvironment. We also addressed the functions of metabolic regulators within non-myocytes in modulating myocardial microenvironment. Finally, we pointed out some interesting and important questions that are needed to be addressed by further studies.

Epigenetic and non-epigenetic mode of SIRT1 action during oocyte meiosis progression

Background

SIRT1 histone deacetylase acts on many epigenetic and non-epigenetic targets. It is thought that SIRT1 is involved in oocyte maturation; therefore, the importance of the ooplasmic SIRT1 pool for the further fate of mature oocytes has been strongly suggested. We hypothesised that SIRT1 plays the role of a signalling molecule in mature oocytes through selected epigenetic and non-epigenetic regulation.

Results

We observed SIRT1 re-localisation in mature oocytes and its association with spindle microtubules. In mature oocytes, SIRT1 distribution shows a spindle-like pattern, and spindle-specific SIRT1 action decreases α-tubulin acetylation. Based on the observation of the histone code in immature and mature oocytes, we suggest that SIRT1 is mostly predestined for an epigenetic mode of action in the germinal vesicles (GVs) of immature oocytes. Accordingly, BML-278-driven trimethylation of lysine K9 in histone H3 in mature oocytes is considered to be a result of GV epigenetic transformation.

Conclusions

Taken together, our observations point out the dual spatiotemporal SIRT1 action in oocytes, which can be readily switched from the epigenetic to non-epigenetic mode of action depending on the progress of meiosis.

Electronic supplementary material

The online version of this article (10.1186/s40104-019-0372-3) contains supplementary material, which is available to authorized users.

Sirt2 epigenetically down-regulates PDGFRα expression and promotes CG4 cell differentiation

We have previously found that Sirt2 enhanced the outgrowth of cellular processes and MBP expression in CG4 cells, where Sirt2 expression is suppressed by transcription factor Nkx2.2. However, the detailed mechanism of Sirt2 facilitating oligodendroglial cell differentiation remained unclear. In the present study, we observed that Sirt2 partially translocated into the nuclei when CG4 cells were induced to differentiate. Sirt2 was detected at the CpG island of PDGFRα promoter via ChIP assay during the cells differentiation process rather than during the state of growth. Sirt2 deacetylated protein(s) bound to the promoter of PDGFRα and simultaneously appeared to facilitate histone3 K27 tri-methylation, both of which are suppressive signatures on gene transcription activation. In bisulfate assay, we identified that Sirt2 significantly induced DNA methylation of PDGFRα promoter compared with the control. Consistently, Sirt2 overexpression down-regulated PDGFRα expression in CG4 cells. The knock-down of PDGFRα or Sirt2 over-expression repressed cell proliferation, but knock-down of Sirt2 promoted cell proliferation. Taken together, Sirt2 translocated into the nuclei while the cells initiated a differentiation process, facilitating CG4 cell differentiation partially through epigenetic modification and suppression of PDGFRα expression. The repression of PDGFRα expression mediated by Sirt2 appeared to facilitate a transition of cellular processes, i.e. from a proliferating progenitor state to a post-mitotic state in CG4 cells.