Project description:SIRT5 is one of the seven members of the NAD+-dependent sirtuin family of protein deacylase that is mainly present in mitochondria and regulates metabolism. In heart, SIRT5 is highly expressed and responsible for succinylation on metabolic enzymes. Although the role of SIRT5 in maintaining cardiac homeostasis under physiological stress and few potential substrates of SIRT5 have been preliminarily revealed, the regulatory network and key cellular signaling pathways involving SIRT5 in myocardial hypertrophy remain largely unknown. Here, we used an established murine model of pressure overload-induced myocardial hypertrophy caused by transverse aortic constriction (TAC) to outline the network and pathway involving SIRT5 in cardiac stress responses. Remarkably, SIRT5 KO mice had enhanced myocardial hypertrophy after TAC surgery compared with wild-type mice.
Project description:Background: Although myocardial hypertrophy is an essential component of heart’s response to many forms of stress, prolonger excessive hypertrophy contributes importantly to the pathogenesis of heart disease. The pimobendan is a drug that both inhibits phosphodiesterase 3 (PDE3) and acts as a calcium sensitizer, which has been used to treat heart failure. The effects of pimobendan on myocardial hypertrophy is controversial. Objective: This study aims to evaluate the therapeutic effect of pimobendan on myocardial hypertrophy. Methods: Mice were treated with low oral doses of pimobendan (1mg/kg/d) for 4 weeks after transaortic constriction. Heart structure and function was assessed using ultrasound, hemodynamic measurements and histology combined with biochemical assessments of myocardial hypertrophy. We also examined the effects of pimobendan (100 µM) on hypertrophy in cultured neonatal rat cardiomyocytes (NRCMs) induced by 50 µM phenylephrine (PE). Results: The doses pimobendan used in our studies had no effect on baseline contractility. Nevertheless, pimobendan administration of mice subjected to TAC decreased heart weights (normalized to either tibia length or body weight) ventricular wall thickness, cardiomyocyte sizes, myocardial fibrosis and the levels of a number of key myocardial hypertrophy markers (WHICH ONES). In cultured neonatal cardiomyocytes, pimobendan attenuated the PE-induced hypertrophy. In both hypertrophy models pimobendan reduced the phosphorylation levels of several essential proteins in the MAPK pathway, PI3K-AKT pathway, and calcineurin signaling pathway. Conclusion: Low pimobendan may attenuate myocardial hypertrophy. Although the underlying mechanisms remain to be elucidated, the MAPK pathway is likely to play a role.
Project description:We are studying the role of human sirtuin SIRT5 during viral infection with SARS-CoV-2. We performed RNA-sequencing of WT and SIRT5-KO human lung adenocarinoma A549 cells overexpressing ACE2 (A549-ACE2), in infected and mock-infected conditions. . Our analysis revealed that SARS-CoV-2 replication is attenuated in SIRT5-KO cells. In addition, SIRT5-KO cells expressed higher basal levels of innate immunity markers and mounted a stronger antiviral response. Our results indicate that SIRT5 is a proviral factor necessary for efficient viral replication.
Project description:Although current studies have demonstrated that lncRNAs play an important part in the pathophysiological process of cardiac disease, whether lncRNAs are associated with the protective role of puerarin in myocardial hypertrophy remains unknown. In the present study, RNA sequencing (RNA-seq) was performed to systematically understand the function of lncRNAs in the pharmacological action of puerarin in myocardial hypertrophy.
Project description:tRNA-derived fragments (tRFs) have served as new class of non-coding RNA and played important role in regulating cellular RNA processing and protein translation, which was also proved have function on the intergenerational effects of paternal disease. However, there was no study reported the influence of tRFs on myocardial hypertrophy. In the current study, we explore the hypothesis that tRFs in response to myocardial hypertrophy and contribute to intergenerational inheritance.We used isoproterenol induced myocardial hypertrophy rat model. Small RNA (< 40 nt) tanscriptome sequencing was used to select differential expressed tRFs. We over-expressed the highest foldchange tRFs on H9c2 cell to check its function in enlarging cardiocytes surface area. We also compared the tRFs expression pattern in F0 sperm and F1 offspring heart between myocardial hypertrophy (Hyp) and control group (Con), as well as evaluated the phynotype of myocardial hypertrophy in F1 offspring. ISO successfully induced a typical cardiac hypertrophy model in our study. Small RNA-seq revealed tRFs were extremely enriched (84%) in Hyp heart. Overexpression tRFs1 and tRFs2 would both enlarge the surface area of cardiac cell and increase hypertrophic markers (ANF, BNP, and β-MHC) expression. tRFs1, tRFs2, tRFs3 and tRFs4 were also significantly high expressed in Hyp F0 sperm and in Hyp F1 offspring heart, but no function of tRFs7, tRFs9 and tRFs10. Compared to Con F1 offspring, Hyp F1 offspring had high expression levels of β-MHC and ANP genes, and increased fibrosis levles and apoptotic cell in heart.We demonstrate that tRFs are involved in regulating the response of myocardial hypertrophy, it might serve as novel epigenetic factor and contribute to intergenerational inheritance of cardiac hypertrophy.
Project description:Background: Exercise can induce physiological myocardial hypertrophy (PMH), and former athletes can live 5-6 years longer than nonathletic controls, suggesting a benefit after regression of PMH. We previously reported that regression of pathological myocardial hypertrophy has antihypertrophic effects. Accordingly, we hypothesized that antihypertrophic memory exists even after PMH has regressed, increasing myocardial resistance to subsequent pathological hypertrophic stress. Methods and Results: C57BL/6 mice were submitted to 21 days of swimming training to develop PMH. After termination of exercise, PMH regressed within 1 week. PMH regression mice (hypertrophic preconditioning group, EHP) and sedentary mice (control group) then underwent transverse aortic constriction (TAC) or a sham operation. At 1 and 4 weeks after TAC, the EHP group showed less increase in myocardial hypertrophy and lower expression of the Nppa and Myh7 genes than the sedentary group. At 4 weeks after TAC, EHP mice had less pulmonary congestion, smaller left ventricular dimensions and end-diastolic pressure, and a larger left ventricular ejection fraction and maximum pressure change rate than sedentary mice. Quantitative polymerase chain reaction (qPCR) revealed that the long noncoding myosin heavy chain associated RNA transcript Mhrt779 was one of the markedly upregulated long noncoding RNAs in the EHP group. Silencing of Mhrt779 attenuated the antihypertrophic effect of EHP in mice with TAC and in cultured cardiomyocytes treated with angiotensin II, and overexpression enhanced the antihypertrophic effect. By chromatin immunoprecipitation assay and qPCR, we found that EHP increased histone 3 trimethylation (H3K4me3 and H3K36me3) at a4 promoter of Mhrt779. Comprehensive identification of RNA-binding proteins by mass spectrometry and Western blot showed that Mhrt779 can bind Brg1 to upregulate Hdac2 and inhibit phosphorylation of Akt and GSK3β. Conclusions: Myocardial hypertrophy preconditioning evoked by exercise increases resistance to pathological stress via an antihypertrophic effect mediated by a signal pathway of Mhrt779 /Hdac2/p-Akt/p-GSK3β.
Project description:Numerous studies found intestinal microbiota alterations which are thought to affect the development of various diseases through the production of gut-derived metabolites. However, the specific metabolites and their pathophysiological contribution to cardiac hypertrophy or heart failure progression still remain unclear. N,N,N-trimethyl-5-aminovaleric acid (TMAVA), derived from trimethyllysine through the gut microbiota, was elevated with gradually increased risk of cardiac mortality and transplantation in a prospective heart failure cohort (n=1647). TMAVA treatment aggravated cardiac hypertrophy and dysfunction in high-fat diet-fed mice. Decreased fatty acid oxidation (FAO) is a hallmark of metabolic reprogramming in the diseased heart and contributes to impaired myocardial energetics and contractile dysfunction. Proteomics uncovered that TMAVA disturbed cardiac energy metabolism, leading to inhibition of FAO and myocardial lipid accumulation. TMAVA treatment altered mitochondrial ultrastructure, respiration and FAO and inhibited carnitine metabolism. Mice with γ-butyrobetaine hydroxylase (BBOX) deficiency displayed a similar cardiac hypertrophy phenotype, indicating that TMAVA functions through BBOX. Finally, exogenous carnitine supplementation reversed TMAVA induced cardiac hypertrophy. These data suggest that the gut microbiota-derived TMAVA is a key determinant for the development of cardiac hypertrophy through inhibition of carnitine synthesis and subsequent FAO.
Project description:Hepatocellular carcinoma (HCC) is a prototypical inflammation-associated cancer and the tumor microenvironment (TME) plays a pivotal role in HCC pathogenesis and response to therapy. The liver is a metabolically active organ, but how liver metabolism impacts TME during HCC development and response to immunotherapy are poorly understood. Here, we show that the metabolic regulator SIRT5 is downregulated in human primary HCC samples, and that Sirt5 deficiency in mice synergizes with oncogenes to increase bile acid (BA) production, which is due to hypersuccinylation and increased BA biosynthesis in the peroxisome. BA acts as a cell-signaling mediator to stimulate its nuclear receptor and promotes M2-like macrophage polarization, thereby creating an immunosuppressive microenvironment favorable for HCC initiating cells. Furthermore, high serum taurocholic acid, a major primary BA, correlates with low SIRT5 expression and increased M2-like tumor-associated macrophages (TAMs) in liver tissue samples from HCC patients. Importantly, administration of cholestyramine, a BA sequestrant and FDA-approved medication for hyperlipemia, reverses the effect of Sirt5 deficiency on promoting M2-like polarized TAMs and liver tumor growth. Our study thus uncovers a novel function of SIRT5 in orchestrating BA metabolism to prevent tumor immune evasion and suppress HCC. These results also suggest a potential strategy using clinically proven bile acid sequestrants for the treatment of HCC patients, especially those with decreased SIRT5 and abnormally high BAs.
Project description:Cutaneous melanoma remains the most lethal skin cancer, and ranks third among all malignancies in terms of years of life lost. Despite the advent of immune checkpoint and targeted therapies, only roughly half of patients with advanced melanoma achieve a durable remission. SIRT5 is a member of the sirtuin family of protein deacylases that regulate metabolism and other biological processes. Germline Sirt5 deficiency is associated with mild phenotypes in mice. Here we show that SIRT5 is required for proliferation and survival across all cutaneous melanoma genotypes tested, as well as uveal melanoma, a genetically distinct melanoma subtype that arises in the eye, and is incurable once metastatic. Likewise, SIRT5 is required for efficient tumor formation by melanoma xenografts, and in an autochthonous mouse Braf;Pten-driven melanoma model. Via metabolite and transcriptomic analyses, we find that SIRT5 is required to maintain histone acetylation and methylation levels in melanoma cells, thereby promoting proper gene expression. SIRT5-dependent genes notably include MITF, a key lineage-specific survival oncogene in melanoma, and the c-MYC proto-oncogene. SIRT5 may represent a novel, druggable genotype-independent addiction in melanoma.
Project description:Sirtuin3 (SIRT3) is well known as a conserved nicotinamide adenine dinucleotide+ (NAD+)-dependent deacetylase located in the mitochondria that may regulate oxidative stress, catabolism and ATP production. Accumulating evidence has recently revealed that SIRT3 plays its critical roles in cardiac fibrosis, myocardial fibrosis and even heart failure (HF) , through its deacetylation modifications. Thus, discovery of SIRT3 activators and elucidating their underlying mechanisms of HF should be urgently needed. Herein, we identified a new small-molecule activator of SIRT3 (named 2-APQC) by the structure-based drug designing strategy. 2-APQC was shown to alleviate isoproterenol (ISO)-induced cardiac hypertrophy and myocardial fibrosis in vitro and in vivo rat models. Importantly, in SIRT3 knockout mice, 2-APQC could not relieve HF, suggesting that 2-APQC is dependent on SIRT3 for its protective role. Mechanically, 2-APQC inhibited the mammalian target of rapamycin-p70 ribosomal protein S6 kinase (p70S6K), c-jun N-terminal kinase (JNK) and transforming growth factor-β (TGF-β)/mothers against decapentaplegic homolog 3 (Smad3) pathways to improve ISO-induced cardiac hypertrophy and myocardial fibrosis. Based upon RNA-seq analyses, we demonstrated that SIRT3-pyrroline-5-carboxylate reductase 1 (PYCR1) axis was closely assoiated with HF. By activating PYCR1, 2-APQC could enhance mitochondrial proline metabolism, inhibited ROS-p38MAPK pathway and thereby protecting against ISO-induced oxidative damage. Moreover, activation of SIRT3 by 2-APQC could facilitate AMPK-Parkin axis to inhibit ISO-induced necrosis. Together, our results demonstrate that 2-APQC is a targeted SIRT3 activator that alleviates myocardial hypertrophy and fibrosis by regulating mitochondrial homeostasis, which may provide a new clue on exploiting a promising drug candidate for the future HF therapeutics.