bims-hafaim Biomed News
on Heart failure metabolism
Issue of 2021–03–07
thirteen papers selected by
Kyle McCommis, Saint Louis University
  1. LARP7 Protects Against Heart Failure by Enhancing Mitochondrial Biogenesis.
  2. Myocardial Hypertrophy and Compensatory Increase in Systolic Function in a Mouse Model of Oxidative Stress.
  3. Ketone bodies are important metabolic fuel for the heart.
  4. CrossTalk Rebuttal" by Gary D. Lopaschuk and Qutuba G. Karwi.
  5. YAP/TFEB pathway promotes autophagic cell death and hypertrophic cardiomyopathy in lysosomal storage diseases.
  6. Effects of Hsp90 inhibitor on the RIP1-RIP3-MLKL pathway during the development of heart failure in mice.
  7. Impact of Cardiac Resynchronization Therapy on Global and Cardiac Metabolism and Cardiac Mitochondrial Function.
  8. Vitamin D3 Supplementation Alleviates Left Ventricular Dysfunction in a Mouse Model of Diet-Induced Type 2 Diabetes: Potential Involvement of Cardiac Lipotoxicity Modulation.
  9. Role of GSK-3 in Cardiac Health: Focusing on Cardiac Remodeling and Heart Failure.
  10. Role of PI3-Kinase in Angiotensin II-Induced Cardiac Hypertrophy: Class I Versus Class III.
  11. Interaction of Obesity and Hypertension on Cardiac Metabolic Remodeling and Survival Following Myocardial Infarction.
  12. Energy Metabolites as Biomarkers in Ischemic and Dilated Cardiomyopathy.
  13. Impact of obesity on day-night differences in cardiac metabolism.
  1. Circulation. 2021 Mar 05.
    LARP7 Protects Against Heart Failure by Enhancing Mitochondrial Biogenesis.
    Huijing Yu, Fang Zhang, Pengyi Yan, Shasha Zhang, Yingmei Lou, Zilong Geng, Zixuan Li, Yan Zhang, Yuejuan Xu, Yanan Lu, Chen Chen, Daowen Wang, Wei Zhu, Xinyang Hu, Jian'an Wang, Tao Zhuang, Yuzhen Zhang, Gengze Wu, Junling Liu, Chunyu Zeng, William T Pu, Kun Sun, Bing Zhang.
      Background: Heart failure (HF) is among the leading causes of morbidity and mortality, and its prevalence continues to rise. La ribonucleoprotein domain family member 7 (LARP7) is a master regulator that governs the DNA damage response and RNAPII pausing pathway, but the role of it in heart failure pathogenesis is incompletely understood. Methods: We assessed LARP7 expression in human HF, and in non-human primate and mouse HF models. To study the function of LARP7 in heart, we generated global and cardiac-specific LARP7 knockout mice. We acutely abolished LARP7 in mature cardiomyocytes by Cas9-mediated LARP7 somatic knockout. We overexpressed LARP7 in cardiomyocytes using adeno-associated virus serotype 9 (AAV9) and ataxia telangiectasia mutated protein (ATM) inhibitor. The therapeutic potential of LARP7-regulated pathways in heart failure was tested in a mouse myocardial infarction model. Results: LARP7 was profoundly downregulated in failing human hearts and in non-human primate and murine hearts after myocardial infarction (MI). Low LARP7 levels in failing hearts was linked to elevated reactive oxygen species (ROS), which activated the ATM-mediated DNA damage response pathway and promoted LARP7 ubiquitination and degradation. Constitutive LARP7 knockout in mouse resulted in impaired mitochondrial biogenesis, myocardial hypoplasia, and midgestational lethality. Cardiac-specific inactivation resulted in defective mitochondrial biogenesis, impaired oxidative phosphorylation, elevated oxidative stress and HF by 4 months of age. These abnormalities were accompanied by reduced SIRT1 stability and deacetylase activity which impaired SIRT1-mediated transcription of genes for oxidative phosphorylation and energy metabolism and dampened cardiac function. Restoring LARP7 expression after MI by either AAV-mediated LARP7 expression or small molecule ATM inhibitor substantially improved the function of injured heart. Conclusions: LARP7 is essential for mitochondrial biogenesis, energy production and cardiac function by modulating SIRT1 homeostasis and activity. Reduction of LARP7 in diseased hearts due to activation of the ATM pathway contributes to heart failure pathogenesis, and restoring LARP7 in the injured heart confers myocardial protection. These results identify the ATM-LARP7-SIRT1 pathway as a target for therapeutic intervention in heart failure.
    Keywords:  LARP7; Mitochondrial biogenesis
    DOI:  https://doi.org/10.1161/CIRCULATIONAHA.120.050812
  2. Int J Mol Sci. 2021 Feb 18. pii: 2039. [Epub ahead of print]22(4):
    Myocardial Hypertrophy and Compensatory Increase in Systolic Function in a Mouse Model of Oxidative Stress.
    Rohan Varshney, Rojina Ranjit, Ying Ann Chiao, Michael Kinter, Bumsoo Ahn.
      Free radicals, or reactive oxygen species, have been implicated as one of the primary causes of myocardial pathologies elicited by chronic diseases and age. The imbalance between pro-oxidants and antioxidants, termed "oxidative stress", involves several pathological changes in mouse hearts, including hypertrophy and cardiac dysfunction. However, the molecular mechanisms and adaptations of the hearts in mice lacking cytoplasmic superoxide dismutase (Sod1KO) have not been investigated. We used echocardiography to characterize cardiac function and morphology in vivo. Protein expression and enzyme activity of Sod1KO were confirmed by targeted mass spectrometry and activity gel. The heart weights of the Sod1KO mice were significantly increased compared with their wildtype peers. The increase in heart weights was accompanied by concentric hypertrophy, posterior wall thickness of the left ventricles (LV), and reduced LV volume. Activated downstream pathways in Sod1KO hearts included serine-threonine kinase and ribosomal protein synthesis. Notably, the reduction in LV volume was compensated by enhanced systolic function, measured by increased ejection fraction and fractional shortening. A regulatory sarcomeric protein, troponin I, was hyper-phosphorylated in Sod1KO, while the vinculin protein was upregulated. In summary, mice lacking cytoplasmic superoxide dismutase were associated with an increase in heart weights and concentric hypertrophy, exhibiting a pathological adaptation of the hearts to oxidative stress.
    Keywords:  CuZnSOD; myocardial hypertrophy; oxidative stress; reactive oxygen species; systolic function; troponin I; vinculin
    DOI:  https://doi.org/10.3390/ijms22042039
  3. J Physiol. 2021 Mar 01.
    Ketone bodies are important metabolic fuel for the heart.
    Qutuba G Karwi, Gary D Lopaschuk.
      
    Keywords:  cardiac efficiency; heart failure; ketone oxidation
    DOI:  https://doi.org/10.1113/JP281004
  4. J Physiol. 2021 Mar 01.
    CrossTalk Rebuttal" by Gary D. Lopaschuk and Qutuba G. Karwi.
    Qutuba G Karwi, Gary D Lopaschuk.
      
    Keywords:  cardiac efficiency; heart failure; ketone oxidation
    DOI:  https://doi.org/10.1113/JP281452
  5. J Clin Invest. 2021 Mar 01. pii: 146821. [Epub ahead of print]131(5):
    YAP/TFEB pathway promotes autophagic cell death and hypertrophic cardiomyopathy in lysosomal storage diseases.
    Inna Rabinovich-Nikitin, Lorrie A Kirshenbaum.
      Lysosomal storage disorders (LSD) are a group of inherited metabolic diseases characterized by lysosomal enzyme deficiency. The cardiac phenotype includes cardiomyopathy with eventual heart failure. Lysosome-mediated degradation processes, such as autophagy, maintain cellular homeostasis by discarding cellular debris and damaged organelles. Under stress, the transcription factor EB (TFEB) moves into the nucleus to activate transcription of lysosome biogenesis and autophagic proteins. In this issue of the JCI, Ikeda et al. report on their exploration of the signaling pathway involved with regulating lysosomal proteins specifically in the heart. The researchers generated a mouse model for LSD that was restricted to cardiac tissue. Unexpectedly, modulation of TFEB alone was insufficient to fully rescue the underlying clearance defect in lysosomal-associated disorders. The authors identified the Yes-associated protein (YAP)/TFEB signaling pathway as a key regulator of autophagosomes. These findings suggest that undigested autophagosomes accumulate and result in the cell death and cardiac dysfunction observed with LSD.
    DOI:  https://doi.org/10.1172/JCI146821
  6. Eur J Pharmacol. 2021 Feb 25. pii: S0014-2999(21)00140-0. [Epub ahead of print] 173987
    Effects of Hsp90 inhibitor on the RIP1-RIP3-MLKL pathway during the development of heart failure in mice.
    Tetsuro Marunouchi, Chiharu Nishiumi, Saki Iinuma, Emi Yano, Kouichi Tanonaka.
      Necroptosis is a programmed form of necrotic cell death. Necroptosis is regulated by the necroptosis-regulating proteins including receptor-interacting protein (RIP) 1, RIP3, and mixed lineage kinase domain-like (MLKL), the activities of which are modulated by the molecular chaperone heat-shock protein (Hsp) 90. Presently, to clarify the relationship between Hsp90 and necroptotic pathway proteins, RIP1, RIP3, and MLKL in the development of heart failure, we examined the effects of Hsp90 inhibitor treatment on the RIP1-RIP3-MLKL pathway in mice following transverse aortic constriction (TAC). In this study, TAC mice showed typical signs of heart failure at the 8th week after the operation. In the failing heart, the levels of these regulatory proteins and those of their phosphorylated forms were increased, suggesting that necroptosis contributed to the development of heart failure in the TAC mice. The increases in RIP1, RIP3, and MLKL after TAC were reversed by the administration of an Hsp90 inhibitor. Furthermore, the rise in the phosphorylation levels of these 3 proteins were attenuated by the Hsp90 inhibitor. Concomitantly, cardiac functions were preserved. We also found that exposure of cultured adult mouse cardiomyocytes to the Hsp90 inhibitor attenuated necrotic cell death induced by tumor necrosis factor-α via suppression of RIP1, RIP3, and MLKL activation in in vitro experiments. Taken together, our findings suggest that inhibition of Hsp90 should have therapeutic effects by reducing the activation of RIP1-RIP3-MLKL pathway in the hypertrophied heart and thus could be a new therapeutic strategy for chronic heart failure.
    Keywords:  Heart failure; Hsp90; MLKL; RIP1; RIP3
    DOI:  https://doi.org/10.1016/j.ejphar.2021.173987
  7. J Card Fail. 2021 Feb 24. pii: S1071-9164(21)00080-4. [Epub ahead of print]
    Impact of Cardiac Resynchronization Therapy on Global and Cardiac Metabolism and Cardiac Mitochondrial Function.
    Pieter Martens, Matthias Dupont, Pieter Vermeersch, Jeroen Dauw, Petra Nijst, Virginie Bito, Liesbet Mesotten, Joris Penders, Stefan Janssens, W H Wilson Tang, Wilfried Mullens.
       BACKGROUND: Alterations in myocardial mitochondrial function and metabolism have been implicated in the pathophysiology of heart failure with reduced ejection fraction (HFrEF). The impact of mechanical dyssynchrony and its alleviation through cardiac resynchronization therapy (CRT) on myocardial mitochondrial function and metabolism remain poorly understood.
    METHODS: HFrEF patients with an indication for CRT underwent targeted metabolomic analysis of 84 energetic substrates at baseline (coronary sinus and peripheral venous blood). Mitochondrial membrane potential (Ψm) as an indicator of mitochondrial function was assessed non-invasively through 99mTC-sestamibi myocardial washout. Changes in peripheral metabolism and Ψm were assessed 6-months after CRT and their association with left ventricular remodeling and peakVO2 was assessed. Principle component analysis (PCA) was used as dimension reduction strategy for metabolic analysis.
    RESULTS: Forty-five HFrEF-patients underwent CRT-implant (76% male, ejection fraction 29±6%). At baseline, PCA of coronary (CS) vs peripheral blood (PB) illustrated preferred cardiac uptake of β-hydroxybutyrate (CS vs PB-ratio=-78%; p<0.005) together with anaplerotic amino-acids, and glycolytic pyruvate breakdown to lactate. Baseline Ψm-dysfunction was associated with shift away from free fatty acids oxidation (FAO). Myocardial β-hydroxybutyrate extraction strongly associated with peakVO2 (-0.836; p<0.001). CRT improved Ψm (25±5% vs 18±6%; p=0.002), in parallel with metabolic remodeling, with increased reliance on FAO, and less reliance on β-hydroxybutyrate and glycolytic pyruvate breakdown to lactate. Changes in myocardial mitochondrial function and metabolism were associated with left ventricular reverse remodeling.
    CONCLUSION: HFrEF-patients exhibit baseline mitochondrial dysfunction, which is associated with alterations in myocardial substrate utilization, including less FAO, more reliance on ketone bodies, anaplerotic amino-acids and the breakdown of glycolytic pyruvate to lactate. CRT is capable of inducing mitochondrial and metabolic reverse remodeling which is associated with cardiac morphology changes.
    Keywords:  Cardiac resynchronization therapy; heart failure; metabolomics; mitochondrial function; remodeling
    DOI:  https://doi.org/10.1016/j.cardfail.2021.02.008
  8. Cardiovasc Drugs Ther. 2021 Mar 04.
    Vitamin D3 Supplementation Alleviates Left Ventricular Dysfunction in a Mouse Model of Diet-Induced Type 2 Diabetes: Potential Involvement of Cardiac Lipotoxicity Modulation.
    Clothilde Philouze, Jean-Charles Martin, Catherine Riva, Alexandra Marziou, Catherine Defoort, Charlène Couturier, Thierry Berton, Julien Astier, Bernard Jover, Nathalie Gayrard, Cyril Reboul, Sandrine Gayrard, Jean-François Landrier, Philippe Obert.
       PURPOSE: To evaluate the effectiveness of vitamin D3 supplementation, in secondary prevention, on cardiac remodeling and function, as well as lipid profile, in a mouse model of diet-induced type 2 diabetes.
    METHODS: Mice were fed a high fat and sucrose diet for 10 weeks. Afterward, diet was maintained for 15 more weeks and two groups were formed, with and without cholecalciferol supplementation. A control group was fed with normal chow. Glucose homeostasis and cardiac function were assessed at baseline and at the 10th and 24th weeks. Animals were killed at the 10th and 25th weeks for plasma and cardiac sample analysis. Cardiac lipid profile was characterized by LC-MS/MS.
    RESULTS: After 10 weeks of diet, mice exhibited pre-diabetes, mild left ventricle hypertrophy, and impaired longitudinal strain, but preserved myocardial circumferential as well as global diastolic and systolic cardiac function. After 15 more weeks of diet, animals presented with well-established type 2 diabetes, pathological cardiac hypertrophy, and impaired regional myocardial function. Cholecalciferol supplementation had no effect on glucose homeostasis but improved cardiac remodeling and regional myocardial function. After 25 weeks, non-supplemented mice exhibited increased myocardial levels of ceramides and diacylglycerol, both of which were normalized by vitamin D3 supplementation.
    CONCLUSION: This work brought to light the beneficial effects of cholecalciferol supplementation, in secondary prevention, on cardiac remodeling and function in a mouse model of diet-induced type 2 diabetes. Those cardioprotective effects may be, at least in part, attributed to the modulation of myocardial levels of lipotoxic species by vitamin D.
    Keywords:  Cardiac lipotoxicity; Regional myocardial function; Type 2 diabetes; Vitamin D
    DOI:  https://doi.org/10.1007/s10557-021-07143-9
  9. Curr Drug Targets. 2021 Feb 23.
    Role of GSK-3 in Cardiac Health: Focusing on Cardiac Remodeling and Heart Failure.
    Ubaid Tariq, Shravan Kumar Uppulapu, Sanjay K Banerjee.
      Glycogen synthase kinase 3 (GSK-3) is a ubiquitously expressed serine/threonine kinase and was first identified as a regulator of glycogen synthase enzyme and glucose homeostasis. It regulates cellular processes like cell proliferation, metabolism, apoptosis and development. Recent findings suggest that GSK-3 is required to maintain the normal cardiac homeostasis that regulates cardiac development, proliferation, hypertrophy and fibrosis. GSK-3 is expressed as two isoforms, α and β. Role of GSK-3α and GSK-3β in cardiac biology is well documented. Both isoforms have common as well as isoform-specific functions. Human data also suggests that GSK-3β is downregulated in hypertrophy and heart failure, and acts as a negative regulator. Pharmacological inhibition of GSK-3α and GSK-3β leads to the endogenous cardiomyocyte proliferation and cardiac regeneration by inducing the upregulation of cell cycle regulators, which results in cell cycle re-entry and DNA synthesis. It was found that cardiac specific knockout (KO) of GSK-3α retained cardiac function, inhibited cardiovascular remodelling and restricted scar expansion during ischemia. Further, knockout of GSK-3α decreases cardiomyocyte apoptosis and enhances its proliferation. However, GSK-3β KO also results in hypertrophic myopathy due to cardiomyocyte hyper-proliferation. Thus GSK-3 inhibitors are named as a double-edged sword because of their beneficial and off target effects. This review focuses on the isoform specific functions of GSK-3 that will help in better understanding about the role of GSK-3α and GSK-3β in cardiac biology and pave a way for the development of new isoform specific GSK-3 modulator for the treatment of ischemic heart disease, cardiac regeneration and heart failure.
    Keywords:  Cardiac hypertrophy; Cardiac regeneration; Cardiomyocyte proliferation; Cardiovascular remodelling; GSK-3
    DOI:  https://doi.org/10.2174/1389450122666210224105430
  10. Front Pharmacol. 2021 ;12 608523
    Role of PI3-Kinase in Angiotensin II-Induced Cardiac Hypertrophy: Class I Versus Class III.
    Tiecheng Zhong, Zonggui Wang, Sayeman Islam Niloy, Yue Shen, Stephen T O'Rourke, Chengwen Sun.
      Cardiac hypertrophy is an adaptive response to cardiac overload initially but turns into a decompensated condition chronically, leading to heart failure and sudden cardiac death. The molecular mechanisms involved in cardiac hypertrophy and the signaling pathways that contribute to the switch from compensation to decompensation are not fully clear. The aim of the current study was to examine the role of PI3-kinases Class I (PI3KC1) and Class III (PI3KC3) in angiotensin (Ang) II-induced cardiac hypertrophy. The results demonstrate that treatment of cardiomyocytes with Ang II caused dose-dependent increases in autophagy, with an increasing phase followed by a decreasing phase. Ang II-induced autophagic increases were potentiated by inhibition of PI3KC1 with LY294002, but were impaired by inhibition of PI3KC3 with 3-methyladenine (3-MA). In addition, blockade of PI3KC1 significantly attenuated Ang II-induced ROS production and cardiomyocyte hypertrophy. In contrast, blockade of PI3KC3 potentiated Ang II-induced ROS production and cardiac hypertrophy. Moreover, blockade of PI3KC1 by overexpression of dominant negative p85 subunit of PI3KC1 significantly attenuated Ang II-induced cardiac hypertrophy in normotensive rats. Taken together, these results demonstrate that both PI3KC1 and PI3KC3 are involved in Ang II-induced cardiac hypertrophy by different mechanisms. Activation of PI3KC1 impairs autophagy activity, leading to accumulation of mitochondrial ROS, and, hence, cardiac hypertrophy. In contrast, activation of PI3KC3 improves autophagy activity, thereby reducing mitochondrial ROS and leads to a protective effect on Ang II-induced cardiac hypertrophy.
    Keywords:  PI3-kinases; angiotensin II; autophagy; cardiac hypertrophy; heart failure
    DOI:  https://doi.org/10.3389/fphar.2021.608523
  11. J Am Heart Assoc. 2021 Mar 05. e018212
    Interaction of Obesity and Hypertension on Cardiac Metabolic Remodeling and Survival Following Myocardial Infarction.
    Alan J Mouton, Elizabeth R Flynn, Sydney P Moak, Xuan Li, Alexandre A da Silva, Zhen Wang, Jussara M do Carmo, Michael E Hall, John E Hall.
      Background Obesity and hypertension are risk factors for myocardial infarction (MI); however, their potential interactions on post-MI outcomes are unclear. We examined interactions of obesity and hypertensionon post-MI function, remodeling, metabolic changes, and recovery. Methods and Results Male and female C57BL/6J mice were provided standard chow or high-fat/fructose diet for 8 weeks and then infused with angiotensin II for 2 weeks to induce hypertension. MI was then induced by surgical ligation of the left coronary artery for 7 days. Obesity alone did not cause cardiac injury or exacerbate hypertension-induced cardiac dysfunction. After MI, however, obese-normotensive mice had lower survival rates compared with chow-fed mice (56% versus 89% males; 54% versus 75% females), which were further decreased by hypertension (29% males; and 35% females). Surviving obese-normotensive males displayed less left ventricular dilation and pulmonary congestion compared with chow-fed males after MI; hypertension reversed left ventricular dilation because of high-fat/fructose diet and promoted significant pulmonary congestion compared with chow-fed controls. Obese-normotensive males displayed higher left ventricular α-MHC (alpha-myosin heavy chain) protein, phosphorylated Akt (protein kinase B) and AMPK (adenosine-monophosphate activated kinase), PPAR-γ (peroxisome proliferator activated receptor gamma), and plasma adiponectin levels after MI, indicating favorable contractile and metabolic changes. However, these favorable contractile and metabolic changes were attenuated by hypertension. Obese-hypertensive males also had lower levels of collagen in the infarcted region, indicating decreased ability to promote an adaptive wound healing response to MI. Conclusions Obesity reduces post-MI survival but is associated with improved post-MI cardiac function and metabolism in surviving normotensive mice. When hypertension accompanies obesity, favorable metabolic pathways associated with obesity are attenuated and post-MI cardiac function and remodeling are adversely impacted.
    Keywords:  angiotensin II; cardiac hypertrophy; heart failure; metabolic syndrome
    DOI:  https://doi.org/10.1161/JAHA.120.018212
  12. Int J Mol Sci. 2021 Feb 18. pii: 1999. [Epub ahead of print]22(4):
    Energy Metabolites as Biomarkers in Ischemic and Dilated Cardiomyopathy.
    Jan Haas, Karen S Frese, Farbod Sedaghat-Hamedani, Elham Kayvanpour, Rewati Tappu, Rouven Nietsch, Oguz Firat Tugrul, Michael Wisdom, Carsten Dietrich, Ali Amr, Tanja Weis, Torsten Niederdränk, Michael P Murphy, Thomas Krieg, Marcus Dörr, Uwe Völker, Jens Fielitz, Norbert Frey, Stephan B Felix, Andreas Keller, Hugo A Katus, Benjamin Meder.
      With more than 25 million people affected, heart failure (HF) is a global threat. As energy production pathways are known to play a pivotal role in HF, we sought here to identify key metabolic changes in ischemic- and non-ischemic HF by using a multi-OMICS approach. Serum metabolites and mRNAseq and epigenetic DNA methylation profiles were analyzed from blood and left ventricular heart biopsy specimens of the same individuals. In total we collected serum from n = 82 patients with Dilated Cardiomyopathy (DCM) and n = 51 controls in the screening stage. We identified several metabolites involved in glycolysis and citric acid cycle to be elevated up to 5.7-fold in DCM (p = 1.7 × 10-6). Interestingly, cardiac mRNA and epigenetic changes of genes encoding rate-limiting enzymes of these pathways could also be found and validated in our second stage of metabolite assessment in n = 52 DCM, n = 39 ischemic HF and n = 57 controls. In conclusion, we identified a new set of metabolomic biomarkers for HF. We were able to identify underlying biological cascades that potentially represent suitable intervention targets.
    Keywords:  cardiomyopathy; energy metabolism; heart failure; multi-omics
    DOI:  https://doi.org/10.3390/ijms22041999
  13. FASEB J. 2021 Mar;35(3): e21298
    Impact of obesity on day-night differences in cardiac metabolism.
    Sobuj Mia, Ravi Sonkar, Lamario Williams, Mary N Latimer, Isabelle Frayne Robillard, Abhinav Diwan, Stuart J Frank, Christine Des Rosiers, Martin E Young.
      An intrinsic property of the heart is an ability to rapidly and coordinately adjust flux through metabolic pathways in response to physiologic stimuli (termed metabolic flexibility). Cardiac metabolism also fluctuates across the 24-hours day, in association with diurnal sleep-wake and fasting-feeding cycles. Although loss of metabolic flexibility has been proposed to play a causal role in the pathogenesis of cardiac disease, it is currently unknown whether day-night variations in cardiac metabolism are altered during disease states. Here, we tested the hypothesis that diet-induced obesity disrupts cardiac "diurnal metabolic flexibility", which is normalized by time-of-day-restricted feeding. Chronic high fat feeding (20-wk)-induced obesity in mice, abolished diurnal rhythms in whole body metabolic flexibility, and increased markers of adverse cardiac remodeling (hypertrophy, fibrosis, and steatosis). RNAseq analysis revealed that 24-hours rhythms in the cardiac transcriptome were dramatically altered during obesity; only 22% of rhythmic transcripts in control hearts were unaffected by obesity. However, day-night differences in cardiac substrate oxidation were essentially identical in control and high fat fed mice. In contrast, day-night differences in both cardiac triglyceride synthesis and lipidome were abolished during obesity. Next, a subset of obese mice (induced by 18-wks ad libitum high fat feeding) were allowed access to the high fat diet only during the 12-hours dark (active) phase, for a 2-wk period. Dark phase restricted feeding partially restored whole body metabolic flexibility, as well as day-night differences in cardiac triglyceride synthesis and lipidome. Moreover, this intervention partially reversed adverse cardiac remodeling in obese mice. Collectively, these studies reveal diurnal metabolic inflexibility of the heart during obesity specifically for nonoxidative lipid metabolism (but not for substrate oxidation), and that restricting food intake to the active period partially reverses obesity-induced cardiac lipid metabolism abnormalities and adverse remodeling of the heart.
    Keywords:  chronobiology; gene expression; heart; metabolism; obesity
    DOI:  https://doi.org/10.1096/fj.202001706RR
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