Abstract P511: Sirtuin 5 Overexpression Protects Against Pressure Overload-Induced Ventricular Dysfunction

Heart failure (HF) is defined as an inability of the heart to pump blood sufficiently to meet the metabolic demands of the body. HF with systolic dysfunction is caused by a progressive decline in contractile function and chronic hemodynamic overload, and characterized by ventricular hypertrophy and remodeling, neurohormonal compensation mechanisms, and myocardial damage. Transverse aortic constriction (TAC) is a well-established model for inducing hypertrophy and HF in rodents. Mice globally deficient in sirtuin 5 (SIRT5), a NAD + -dependent deacylase, are hypersensitive to cardiac stress and display increased mortality after TAC. Prior studies assessing SIRT5 functions in the heart have all employed loss-of-function approaches. In this study, we generated SIRT5 overexpressing (SIRT5OE) mice, and evaluated their response to chronic pressure overload using TAC. Compared to littermate controls, elevated SIRT5 levels promoted maintenance of cardiac contractile function after 4 weeks of pressure overload, at which point control mice had developed systolic dysfunction, characterized by decreased EF, coupled with ventricular dilation, remodeling and fibrosis. Transcriptomic analysis revealed that SIRT5 suppresses key HF sequelae, including metabolic switch from fatty acid oxidation to glycolysis and immune activation ( i.e., TGFβ, IL6, Renin-Angiotensin, and NFAT, and fibrotic signaling pathways). We conclude that SIRT5 is a limiting factor in the preservation of cardiac function in response to experimental pressure overload.

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Sirtuin 5 levels are limiting in preserving cardiac function and suppressing fibrosis in response to pressure overload

10.1101/2021.06.15.448619 ◽

2021 ◽

Author(s):

Angela H Guo ◽

Rachael K Baliira ◽

Mary E Skinner ◽

Surinder Kumar ◽

Anthony Andren ◽

...

Keyword(s):

Cardiac Function ◽

Systolic Function ◽

Cardiac Contractility ◽

Pressure Overload ◽

Left Ventricular ◽

Acid Oxidation ◽

Limiting Factor ◽

Loss Of Function ◽

Metabolic Switch ◽

Ventricular Fibrosis

Heart failure (HF) is defined as an inability of the heart to pump blood adequately to meet the body's metabolic demands. HF with reduced systolic function is characterized by cardiac hypertrophy, ventricular fibrosis and remodeling, and decreased cardiac contractility, leading to cardiac functional impairment and death. Transverse aortic constriction (TAC) is a well-established model for inducing hypertrophy and HF in rodents. Mice globally deficient in sirtuin 5 (SIRT5), a NAD+-dependent deacylase, are hypersensitive to cardiac stress and display increased mortality after TAC. Prior studies assessing SIRT5 functions in the heart have all employed loss-of-function approaches. In this study, we generated SIRT5 overexpressing (SIRT5OE) mice, and evaluated their response to chronic pressure overload induced by TAC. Compared to littermate controls, SIRT5OE mice were protected from left ventricular dilation and impaired ejection fraction, adverse functional consequences of TAC. Transcriptomic analyses revealed that SIRT5 suppresses key HF sequelae, including the metabolic switch from fatty acid oxidation to glycolysis, immune activation, and increased fibrotic signaling. We conclude that SIRT5 is a limiting factor in the preservation of cardiac function in response to experimental pressure overload.

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Ncor2/PPARα-dependent upregulation of MCUb in the type 2 diabetic heart impacts cardiac metabolic flexibility and function

10.2337/figshare.13342229 ◽

2020 ◽

Author(s):

Ada Admin ◽

Federico Cividini ◽

Brian T Scott ◽

Jorge Suarez ◽

Darren E. Casteel ◽

...

Keyword(s):

Contractile Function ◽

Pyruvate Dehydrogenase Complex ◽

Dominant Negative ◽

Diabetic Heart ◽

Acid Oxidation ◽

Cardiac Contractile Function ◽

Mitochondrial Fatty Acid Oxidation ◽

Mitochondrial Fatty Acid ◽

Type 2 Diabetic

The contribution of altered mitochondrial Ca2+ handling to metabolic and functional defects in type 2 diabetic (T2D) mouse hearts is not well understood. Here, we show that the T2D heart is metabolically inflexible and almost exclusively dependent on mitochondrial fatty acid oxidation as a consequence of mitochondrial calcium uniporter complex (MCUC) inhibitory subunit MCUb overexpression. Using a recombinant endonuclease-deficient Cas9 (dCas9)-based gene promoter pull-down approach coupled with mass spectrometry we found that MCUb is upregulated in the T2D heart due to loss of glucose homeostasis regulator nuclear receptor co-repressor 2 (Ncor2) repression, and ChIP assays identified PPARα as a mediator of MCUb gene expression in T2D cardiomyocytes. Upregulation of MCUb limits mitochondrial matrix Ca2+ uptake and impairs mitochondrial energy production via glucose oxidation, by depressing Pyruvate Dehydrogenase Complex (PDC) activity. Gene therapy displacement of endogenous MCUb with a dominant-negative MCUb transgene (MCUbW246R/V251E) in vivo rescued T2D cardiomyocytes from metabolic inflexibility, and stimulated cardiac contractile function and adrenergic responsiveness by enhancing phospholamban (PLN) phosphorylation via Protein Kinase A (PKA). We conclude that MCUb represents one newly-discovered molecular effector at the interface of metabolism and cardiac function, and its repression improves the outcome of the chronically-stressed diabetic heart.

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Ncor2/PPARα-dependent upregulation of MCUb in the type 2 diabetic heart impacts cardiac metabolic flexibility and function

10.2337/figshare.13342229.v1 ◽

2020 ◽

Author(s):

Ada Admin ◽

Federico Cividini ◽

Brian T Scott ◽

Jorge Suarez ◽

Darren E. Casteel ◽

...

Keyword(s):

Contractile Function ◽

Pyruvate Dehydrogenase Complex ◽

Dominant Negative ◽

Diabetic Heart ◽

Acid Oxidation ◽

Cardiac Contractile Function ◽

Mitochondrial Fatty Acid Oxidation ◽

Mitochondrial Fatty Acid ◽

Type 2 Diabetic

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Abstract 12606: Autophagy is Required for Mitochondrial Biogenesis in the Heart

Circulation ◽

10.1161/circ.130.suppl_2.12606 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Zhonggang Li ◽

Quanjiang Zhang ◽

Karla Pires ◽

E. Dale Abel

Keyword(s):

Heart Failure ◽

Mitochondrial Dysfunction ◽

Mitochondrial Biogenesis ◽

Contractile Function ◽

Heart Function ◽

Early Event ◽

Acid Oxidation ◽

Cardiac Contractile Function ◽

Cardiac Contractile ◽

Deficient Mice

Autophagy is an essential process that maintains cellular homeostasis via lysosomal degradation pathways. Autophagy has been found to be involved in various pathophysiological conditions in the heart, including myocardial hypertrophy and ischemic heart disease. However, the precise mechanism by which autophagy maintains cardiac function in the non-stressed heart is incompletely understood. We generated cardiac-specific ATG3 deficient mice (cATG3 KO mice) by crossing αMHC-Cre mice with floxed ATG3 mice. Relative to their wild type (WT) littermates, cATG3 KO mice revealed reduced ATG3 expression and inhibited autophagy specifically in the heart. At 4 months of age, cATG3 KO mice showed impaired cardiac contractile function, characterized by a 25% reduction in fractional shortening by echocardiography (p <0.01), Moreover, cATG3 KO mice revealed increased lipid accumulation, reduced fatty acid oxidation and impaired mitochondrial respirations in the heart, without evidence of fibrosis or inflammation. Mitochondrial dysfunction in cATG3 KO mice was accompanied with mitochondrial content loss and reduced expression of mitochondrial biogenesis related genes (PGC1α, NRF1, NRF2 and TFAM). Interestingly, autophagy inhibition, induced mitochondrial biogenesis defects and mitochondrial dysfunction in neonatal cATG3 KO mice (1 week old), prior to the onset of cardiac contractile dysfunction and heart failure, suggesting that cardiac mitochondrial dysfunction may be an early event in the progression of heart failure in the autophagy deficient mice. Finally, in response to exercise training mitochondrial biogenesis (PGC1 alpha induction and increased respiration rates) was completely inhibited in ATG3 deficient mice. In conclusion, autophagy is essential for generating signals that promote mitochondrial biogenesis, and is indispensable for normal heart function under basal conditions.

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Compromised Myocardial Energetics in Hypertrophied Mouse Hearts Diminish the Beneficial Effect of Overexpressing SERCA2a

Journal of Biological Chemistry ◽

10.1074/jbc.m110.210757 ◽

2011 ◽

Vol 286 (12) ◽

pp. 10163-10168 ◽

Cited By ~ 29

Author(s):

Ilka Pinz ◽

Rong Tian ◽

Darrell Belke ◽

Eric Swanson ◽

Wolfgang Dillmann ◽

...

Keyword(s):

Energy Cost ◽

Energy Supply ◽

Contractile Function ◽

Supply And Demand ◽

Pressure Overload ◽

Myocardial Contraction ◽

Left Ventricular ◽

Limiting Factor ◽

Sham Operation ◽

Inotropic Response

The sarcoplasmic reticulum calcium ATPase (SERCA) plays a central role in regulating intracellular Ca2+ homeostasis and myocardial contractility. Several studies show that improving Ca2+ handling in hypertrophied rodent hearts by increasing SERCA activity results in enhanced contractile function. This suggests that SERCA is a potential target for gene therapy in cardiac hypertrophy and failure. However, it raises the issue of increased energy cost resulting from a higher ATPase activity. In this study, we determined whether SERCA overexpression alters the energy cost of increasing myocardial contraction in mouse hearts with pressure-overload hypertrophy using 31P NMR spectroscopy. We isolated and perfused mouse hearts from wild-type (WT) and transgenic (TG) mice overexpressing the cardiac isoform of SERCA (SERCA2a) 8 weeks after ascending aortic constriction (left ventricular hypertrophy (LVH)) or sham operation. We found that overexpressing SERCA2a enhances myocardial contraction and relaxation in normal mouse hearts during inotropic stimulation with isoproterenol. Energy consumption was proportionate to the increase in contractile function. Thus, increasing SERCA2a expression in the normal heart allows an enhanced inotropic response with no compromise in energy supply and demand. However, this advantage was not sustained in LVH hearts in which the energetic status was compromised. Although the overexpression of SERCA2a prevented the down-regulation of SERCA protein in LVH hearts, TG-LVH hearts showed no increase in inotropic response when compared with WT-LVH hearts. Our results suggest that energy supply may be a limiting factor for the benefit of SERCA overexpression in hypertrophied hearts. Thus, strategies combining energetic support with increasing SERCA activity may improve the therapeutic effectiveness for heart failure.

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Enhancing calmodulin binding to cardiac ryanodine receptor completely inhibits pressure-overload induced hypertrophic signaling

Communications Biology ◽

10.1038/s42003-020-01443-w ◽

2020 ◽

Vol 3 (1) ◽

Author(s):

Michiaki Kohno ◽

Shigeki Kobayashi ◽

Takeshi Yamamoto ◽

Ryosuke Yoshitomi ◽

Toshiro Kajii ◽

...

Keyword(s):

Cardiac Hypertrophy ◽

Binding Affinity ◽

Ryanodine Receptor ◽

Contractile Function ◽

Pressure Overload ◽

Cardiac Contractile Function ◽

Calmodulin Binding ◽

Intracellular Ca ◽

Hypertrophic Signaling ◽

Cardiac Ryanodine Receptor

AbstractCardiac hypertrophy is a well-known major risk factor for poor prognosis in patients with cardiovascular diseases. Dysregulation of intracellular Ca2+ is involved in the pathogenesis of cardiac hypertrophy. However, the precise mechanism underlying cardiac hypertrophy remains elusive. Here, we investigate whether pressure-overload induced hypertrophy can be induced by destabilization of cardiac ryanodine receptor (RyR2) through calmodulin (CaM) dissociation and subsequent Ca2+ leakage, and whether it can be genetically rescued by enhancing the binding affinity of CaM to RyR2. In the very initial phase of pressure-overload induced cardiac hypertrophy, when cardiac contractile function is preserved, reactive oxygen species (ROS)-mediated RyR2 destabilization already occurs in association with relaxation dysfunction. Further, stabilizing RyR2 by enhancing the binding affinity of CaM to RyR2 completely inhibits hypertrophic signaling and improves survival. Our study uncovers a critical missing link between RyR2 destabilization and cardiac hypertrophy.

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Let-7 family of microRNA is required for maturation and adult-like metabolism in stem cell-derived cardiomyocytes

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1424042112 ◽

2015 ◽

Vol 112 (21) ◽

pp. E2785-E2794 ◽

Cited By ~ 132

Author(s):

Kavitha T. Kuppusamy ◽

Daniel C. Jones ◽

Henrik Sperber ◽

Anup Madan ◽

Karin A. Fischer ◽

...

Keyword(s):

Stem Cell ◽

Fatty Acid ◽

Large Scale ◽

Metabolic Flux ◽

Embryonic Stem ◽

Acid Oxidation ◽

Loss Of Function ◽

Metabolic Switch ◽

Cardiac Maturation

In metazoans, transition from fetal to adult heart is accompanied by a switch in energy metabolism-glycolysis to fatty acid oxidation. The molecular factors regulating this metabolic switch remain largely unexplored. We first demonstrate that the molecular signatures in 1-year (y) matured human embryonic stem cell-derived cardiomyocytes (hESC-CMs) are similar to those seen in in vivo-derived mature cardiac tissues, thus making them an excellent model to study human cardiac maturation. We further show that let-7 is the most highly up-regulated microRNA (miRNA) family during in vitro human cardiac maturation. Gain- and loss-of-function analyses of let-7g in hESC-CMs demonstrate it is both required and sufficient for maturation, but not for early differentiation of CMs. Overexpression of let-7 family members in hESC-CMs enhances cell size, sarcomere length, force of contraction, and respiratory capacity. Interestingly, large-scale expression data, target analysis, and metabolic flux assays suggest this let-7–driven CM maturation could be a result of down-regulation of the phosphoinositide 3 kinase (PI3K)/AKT protein kinase/insulin pathway and an up-regulation of fatty acid metabolism. These results indicate let-7 is an important mediator in augmenting metabolic energetics in maturing CMs. Promoting maturation of hESC-CMs with let-7 overexpression will be highly significant for basic and applied research.

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Dual specific phosphatase 12 ameliorates cardiac hypertrophy in response to pressure overload

Clinical Science ◽

10.1042/cs20160664 ◽

2016 ◽

Vol 131 (2) ◽

pp. 141-154 ◽

Cited By ~ 6

Author(s):

Wei-ming Li ◽

Yi-fan Zhao ◽

Guo-fu Zhu ◽

Wen-hui Peng ◽

Meng-yun Zhu ◽

...

Keyword(s):

Cardiac Hypertrophy ◽

Cardiac Function ◽

Contractile Function ◽

Pressure Overload ◽

Loss Of Function ◽

Pathological Cardiac Hypertrophy ◽

Dual Specific Phosphatase

Pathological cardiac hypertrophy is an independent risk factor of heart failure. However, we still lack effective methods to reverse cardiac hypertrophy. DUSP12 is a member of the dual specific phosphatase (DUSP) family, which is characterized by its DUSP activity to dephosphorylate both tyrosine and serine/threonine residues on one substrate. Some DUSPs have been identified as being involved in the regulation of cardiac hypertrophy. However, the role of DUSP12 during pathological cardiac hypertrophy is still unclear. In the present study, we observed a significant decrease in DUSP12 expression in hypertrophic hearts and cardiomyocytes. Using a genetic loss-of-function murine model, we demonstrated that DUSP12 deficiency apparently aggravated pressure overload-induced cardiac hypertrophy and fibrosis as well as impaired cardiac function, whereas cardiac-specific overexpression of DUPS12 was capable of reversing this hypertrophic and fibrotic phenotype and improving contractile function. Furthermore, we demonstrated that JNK1/2 activity but neither ERK1/2 nor p38 activity was increased in the DUSP12 deficient group and decreased in the DUSP12 overexpression group both in vitro and in vivo under hypertrophic stress conditions. Pharmacological inhibition of JNK1/2 activity (SP600125) is capable of reversing the hypertrophic phenotype in DUSP12 knockout (KO) mice. DUSP12 protects against pathological cardiac hypertrophy and related pathologies. This regulatory role of DUSP12 is primarily through c-Jun N-terminal kinase (JNK) inhibition. DUSP12 could be a promising therapeutic target of pathological cardiac hypertrophy. DUSP12 is down-regulated in hypertrophic hearts. An absence of DUSP12 aggravated cardiac hypertrophy, whereas cardiomyocyte-specific DUSP12 overexpression can alleviate this hypertrophic phenotype with improved cardiac function. Further study demonstrated that DUSP12 inhibited JNK activity to attenuate pathological cardiac hypertrophy.

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Abstract 113: Targeting Receptor-interacting Protein 140 (RIP140) To Modulate Energy Metabolism In The Failing Heart

Circulation Research ◽

10.1161/res.129.suppl_1.113 ◽

2021 ◽

Vol 129 (Suppl_1) ◽

Author(s):

Tsunehisa Yamamoto ◽

Kirill Batmanov ◽

Elizabeth Pruzinsky ◽

Yang Xiao ◽

Swapnil V Shewale ◽

...

Keyword(s):

Ventricular Remodeling ◽

Contractile Function ◽

Systolic Dysfunction ◽

Left Ventricular ◽

Acid Oxidation ◽

Nmr Studies ◽

Interacting Protein ◽

Atp Production ◽

Failing Heart ◽

Mitochondrial Fatty Acid

During the development of heart failure (HF), the PPAR/ERR complex becomes deactivated resulting in diminished capacity for mitochondrial fatty acid oxidation (FAO) and ATP production leading to an “energy-starved” state that contributes to progression of HF. Receptor-Interacting protein 140 (RIP140) serves as a co-repressor of PPAR/ERR in some extra-cardiac tissues. We hypothesized that inhibition of RIP140 would re-activate PPAR/ERR enhancing capacity for fuel catabolism and ATP production in the failing heart. Heart and skeletal muscle-specific RIP140 knockout mice (strRIP140KO) were resistant to the development of cardiac hypertrophy and diastolic dysfunction in response to chronic pressure overload that mimicked features of HF with preserved ejection fraction (HFpEF). To further evaluate the role of RIP140 in heart, cardiac-specific (cs) RIP140KO mice were generated. 13 C-substrate NMR studies demonstrated that palmitate oxidation and triglyceride turnover rates were significantly accelerated in isolated perfused csRIP140KO hearts. csRIP140KO were subjected to transverse aortic constriction/apical myocardial infarction surgery (TAC/MI), to produce HF with reduced EF (HFrEF). Compared to controls, csRIP140KO exhibited reduced left ventricular remodeling and systolic dysfunction when subjected to TAC/MI. RNA-sequence analysis demonstrated that many genes involved in FAO, branched-chain amino acid catabolism, oxidative phosphorylation, and adult muscle contraction programs were significantly “protected” (less downregulation) by RIP140 deletion in the context of TAC/MI. To identify candidate cardiac RIP140 targets, “CUT&RUN”-sequencing was conducted on cardiomyocytes (CM) from csRIP140KO and controls to identify changes in enhancer regions. Motif analysis of peaks with increased H3K27ac deposition in the csRIP140KO CM identified ERR, PPAR, myocyte enhancer 2 (MEF2), glucocorticoid receptor (GR), and kruppel-like factor (KLF) binding sites. We conclude that RIP140 serves as a global co-repressor of a network of transcription factors that control cardiac energy metabolic and contractile function, and that inhibition of RIP140 could prove to be a novel therapeutic approach for HF.

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