Sugar or fat: The metabolic choice of the trained heart

Valerenic acid attenuates pathological myocardial hypertrophy by promoting the utilization of multiple substrates in the mitochondrial energy metabolism

INTRODUCTION

Valerenic acid (VA) is a unique and biologically active component in Valeriana officinalis L., which has been reported to have a regulatory effect on the cardiovascular system. However, its therapeutic effects on pathological myocardial hypertrophy (PMH) and the underlying mechanisms are undefined.

OBJECTIVES

Our study aims to elucidate how VA improves PMH, and preliminarily discuss its mechanism.

METHODS

The efficacy of VA on PMH was confirmed by in vivo and in vitro experiments and the underlying mechanism was investigated by molecular dynamics (MD) simulations and specific siRNA interference.

RESULTS

VA enhanced cardiomyocyte fatty acid oxidation (FAO), inhibited hyper-activated glycolysis, and improved the unbalanced pyruvate-lactate axis. VA could significantly improve impaired mitochondrial function and reduce the triglyceride (TG) in the hypertrophic myocardium while reducing the lactate (LD) content. Molecular mechanistic studies showed that VA up-regulated the expression of peroxisome proliferator-activated receptor-α (PPARα) and downstream FAO-related genes including CD36, CPT1A, EHHADH, and MCAD. VA reduced the expression of ENO1 and PDK4, the key enzymes in glycolysis. Meanwhile, VA improved the pyruvate-lactate axis and promoted the aerobic oxidation of pyruvate by inhibiting LDAH and MCT4. MD simulations confirmed that VA can bind with the F273 site of PPARα, which proposes VA as a potential activator of the PPARα.

CONCLUSION

Our results demonstrated that VA might be a potent activator for the PPARα-mediated pathway. VA directly targets the PPARα and subsequently promotes energy metabolism to attenuate PMH, which can be applied as a potentially effective drug for the treatment of HF.

A tipping point in dihydroxyacetone exposure: mitochondrial stress and metabolic reprogramming alter survival in rat cardiomyocytes H9c2 cells

Exogenous exposures to the triose sugar dihydroxyacetone (DHA) occur from sunless tanning products and electronic cigarette aerosol. Once inhaled or absorbed, DHA enters cells, is converted to dihydroxyacetone phosphate (DHAP), and incorporated into several metabolic pathways. Cytotoxic effects of DHA vary across the cell types depending on the metabolic needs of the cells, and differences in the generation of reactive oxygen species (ROS), cell cycle arrest, and mitochondrial dysfunction have been reported. We have shown that cytotoxic doses of DHA induced metabolic imbalances in glycolysis and oxidative phosphorylation in liver and kidney cell models. Here, we examine the dose-dependent effects of DHA on the rat cardiomyocyte cell line, H9c2. Cells begin to experience cytotoxic effects at low millimolar doses, but an increase in cell survival was observed at 2 mM DHA. We confirmed that 2 mM DHA increased cell survival compared to the low cytotoxic 1 mM dose and investigated the metabolic differences between these two low DHA doses. Exposure to 1 mM DHA showed changes in the cell's fuel utilization, mitochondrial reactive oxygen species (ROS), and transient changes in the glycolysis and mitochondrial energetics, which normalized 24 h after exposure. The 2 mM dose induced robust changes in mitochondrial flux through acetyl CoA and elevated expression of fatty acid synthase. Distinct from the 1 mM dose, the 2 mM exposure increased mitochondrial ROS and NAD(P)H levels, and sustained changes in LDHA/LDHB and acetyl CoA-associated enzymes were observed. Although the cells were exposed to low cytotoxic (1 mM) and non-cytotoxic (2 mM) acute doses of DHA, significant changes in mitochondrial metabolic pathways occurred. Further, the proliferation increase at the acute 2 mM DHA dose suggests a metabolic adaption occurred with sustained consequences in survival and proliferation. With increased exogenous exposure to DHA through e-cigarette aerosol, this work suggests cell metabolic changes induced by acute or potentially chronic exposures could impact cell function and survival.

Elastic porous microspheres/extracellular matrix hydrogel injectable composites releasing dual bio-factors enable tissue regeneration

Injectable biomaterials have garnered increasing attention for their potential and beneficial applications in minimally invasive surgical procedures and tissue regeneration. Extracellular matrix (ECM) hydrogels and porous synthetic polymer microspheres can be prepared for injectable administration to achieve in situ tissue regeneration. However, the rapid degradation of ECM hydrogels and the poor injectability and biological inertness of most polymeric microspheres limit their pro-regenerative capabilities. Here, we develop a biomaterial system consisting of elastic porous poly(l-lactide-co-ε-caprolactone) (PLCL) microspheres mixed with ECM hydrogels as injectable composites with interleukin-4 (IL-4) and insulin-like growth factor-1 (IGF-1) dual-release functionality. The developed multifunctional composites have favorable injectability and biocompatibility, and regulate the behavior of macrophages and myogenic cells following injection into muscle tissue. The elicited promotive effects on tissue regeneration are evidenced by enhanced neomusle formation, vascularization, and neuralization at 2-months post-implantation in a male rat model of volumetric muscle loss. Our developed system provides a promising strategy for engineering bioactive injectable composites that demonstrates desirable properties for clinical use and holds translational potential for application as a minimally invasive and pro-regenerative implant material in multiple types of surgical procedures.

Exercise increases MEF2A abundance in rat cardiac muscle by downregulating microRNA-223-5p

Exercise plays an important role in cardiac health and enhances the transport of glucose in cardiac muscle by increasing the glucose transporter-4 (GLUT4) content at the cell membrane. The GLUT4 gene is a target of myocyte enhancer transcription factor 2A (MEF2A). Several transcription factors are regulated by microRNAs (miRs), small non-coding RNAs that control gene expression at the posttranscriptional level. In this study we tested the hypothesis that exercise regulates the expression of miR-223 and that MEF2A is a direct target of miR-223. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blot experiments showed that GLUT4 gene expression and protein abundance increased by 30 and 23%, respectively, in the microsomal fraction immediately after exercise, and had returned to control levels after 18 h. In contrast, the increase in GLUT4 in the membrane fraction was delayed. Exercise also increased the protein abundance of transcription factors involved in GLUT4 expression. Immediately after exercise, the protein abundance of MEF2A, nuclear respiratory factor 1 (NRF1), and forkhead box O1 (FOXO1) increased by 18, 30, and 40%, respectively. qRT-PCR experiments showed that miR-223-3p and miR-223-5p expression decreased immediately after exercise by 60 and 30%, respectively, and luciferase assays indicated that MEF2A is a target of the 5p strand of miR-223. Overexpression of miR-223-5p in H9c2 cells decreased the protein abundance of MEF2A. Our results suggest that the exercise-induced increase in GLUT4 content in cardiac muscle is partly due to the posttranscriptional increase in MEF2A protein abundance caused by the decrease in miR-223-5p expression. The exercise-induced decrease in miR-223-3p expression likely contributes to the increases in NRF1 and FOXO1 abundance and GLUT4 content.

Abnormalities of glucose and lipid metabolism in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury is a common condition in cardiovascular diseases, and the mechanism of its occurrence involves multiple complex metabolic pathways and signaling pathways. Among these pathways, glucose metabolism and lipid metabolism play important roles in regulating myocardial energy metabolism. Therefore, this article focuses on the roles of glucose metabolism and lipid metabolism in myocardial ischemia-reperfusion injury, including glycolysis, glucose uptake and transport, glycogen metabolism and the pentose phosphate pathway; and triglyceride metabolism, fatty acid uptake and transport, phospholipid metabolism, lipoprotein metabolism, and cholesterol metabolism. Finally, due to the different alterations and development of glucose metabolism and lipid metabolism in myocardial ischemia-reperfusion, there are also complex interregulatory relationships between them. In the future, modulating the equilibrium between glucose metabolism and lipid metabolism in cardiomyocytes and ameliorating aberrations in myocardial energy metabolism represent highly promising novel strategies for addressing myocardial ischemia-reperfusion injury. Therefore, a comprehensive exploration of glycolipid metabolism can offer novel theoretical and clinical insights into the prevention and treatment of myocardial ischemia-reperfusion injury.

Exercise training maintains cardiovascular health: signaling pathways involved and potential therapeutics

Exercise training has been widely recognized as a healthy lifestyle as well as an effective non-drug therapeutic strategy for cardiovascular diseases (CVD). Functional and mechanistic studies that employ animal exercise models as well as observational and interventional cohort studies with human participants, have contributed considerably in delineating the essential signaling pathways by which exercise promotes cardiovascular fitness and health. First, this review summarizes the beneficial impact of exercise on multiple aspects of cardiovascular health. We then discuss in detail the signaling pathways mediating exercise's benefits for cardiovascular health. The exercise-regulated signaling cascades have been shown to confer myocardial protection and drive systemic adaptations. The signaling molecules that are necessary for exercise-induced physiological cardiac hypertrophy have the potential to attenuate myocardial injury and reverse cardiac remodeling. Exercise-regulated noncoding RNAs and their associated signaling pathways are also discussed in detail for their roles and mechanisms in exercise-induced cardioprotective effects. Moreover, we address the exercise-mediated signaling pathways and molecules that can serve as potential therapeutic targets ranging from pharmacological approaches to gene therapies in CVD. We also discuss multiple factors that influence exercise's effect and highlight the importance and need for further investigations regarding the exercise-regulated molecules as therapeutic targets and biomarkers for CVD as well as the cross talk between the heart and other tissues or organs during exercise. We conclude that a deep understanding of the signaling pathways involved in exercise's benefits for cardiovascular health will undoubtedly contribute to the identification and development of novel therapeutic targets and strategies for CVD.

Exercise-induced signaling pathways to counteracting cardiac apoptotic processes

Cardiovascular diseases are the most common cause of death in the world. One of the major causes of cardiac death is excessive apoptosis. However, multiple pathways through moderate exercise can reduce myocardial apoptosis. After moderate exercise, the expression of anti-apoptotic proteins such as IGF-1, IGF-1R, p-PI3K, p-Akt, ERK-1/2, SIRT3, PGC-1α, and Bcl-2 increases in the heart. While apoptotic proteins such as PTEN, PHLPP-1, GSK-3, JNK, P38MAPK, and FOXO are reduced in the heart. Exercise-induced mechanical stress activates the β and α5 integrins and subsequently, focal adhesion kinase phosphorylation activates the Akt/mTORC1 and ERK-1/2 pathways, leading to an anti-apoptotic response. One of the reasons for the decrease in exercise-induced apoptosis is the decrease in Fas-ligand protein, Fas-death receptor, TNF-α receptor, Fas-associated death domain (FADD), caspase-8, and caspase-3. In addition, after exercise mitochondrial-dependent apoptotic factors such as Bid, t-Bid, Bad, p-Bad, Bak, cytochrome c, and caspase-9 are reduced. These changes lead to a reduction in oxidative damage, a reduction in infarct size, a reduction in cardiac apoptosis, and an increase in myocardial function. After exercising in the heart, the levels of RhoA, ROCK1, Rac1, and ROCK2 decrease, while the levels of PKCε, PKCδ, and PKCɑ are activated to regulate calcium and prevent mPTP perforation. Exercise has an anti-apoptotic effect on heart failure by increasing the PKA-Akt-eNOS and FSTL1-USP10-Notch1 pathways, reducing the negative effects of CaMKIIδ, and increasing the calcineurin/NFAT pathway. Exercise plays a protective role in the heart by increasing HSP20, HSP27, HSP40, HSP70, HSP72, and HSP90 along with increasing JAK2 and STAT3 phosphorylation. However, research on exercise and factors such as Pim-1, Notch, and FAK in cardiac apoptosis is scarce, so further research is needed. Future research is recommended to discover more anti-apoptotic pathways. It is also recommended to study the synergistic effect of exercise with gene therapy, dietary supplements, and cell therapy for future research.

[Molecular mechanisms of adaptive and therapeutic effects of physical activity in patients with cardiovascular diseases]

Physical activity is one of the main components of the rehabilitation of patients with cardiovascular disease (CVD). As shown by practice and the results of evidence-based studies, the beneficial effects of physical activity on disease outcomes in a number of cardiac nosologies are comparable to drug treatment. This gives the doctor another tool to influence the unfavorable epidemiological situation in developed countries with the spread of diseases of the cardiovascular system and CVD mortality. Reliable positive results of cardiorehabilitation (CR) were obtained using various methods. The goal of CR is to restore the optimal physiological, psychological and professional status, reduce the risk of CVD and mortality. In most current CVD guidelines worldwide, cardiac rehabilitation is a Class I recommendation. The molecular mechanisms described in the review, initiated by physical activity, underlie the multifactorial effect of the latter on the function of the cardiovascular system and the course of cardiac diseases. Physical exercise is an important component of the therapeutic management of patients with CVD, which is supported by the results of a meta-analysis of 63 studies associated with various forms of aerobic exercise of varying intensity (from 50 to 95% VO₂) for 1 to 47 months, which showed that CR based on physical exercise improves cardiorespiratory endurance. Knowledge of the molecular basis of the influence of physical activity makes it possible to use biochemical markers to assess the effectiveness of rehabilitation programs.

Structural analysis and functional study of phosphofructokinase B (PfkB) from Mycobacterium marinum

Phosphofructokinase B (PfkB) belongs to the ribokinase family, which uses the phosphorylated sugar as substrate, and catalyzes fructose-6-phosphate into fructose-1,6-diphosphate. However, the structural basis of Mycobacterium marinum PfkB is not clear. Here, we found that the PfkB protein was monomeric in solution, which was different from most enzymes in this family. The crystal structure of PfkB protein from M. marinum was solved at a resolution of 2.21 Å. The PfkB structure consists of two domains, a major three-layered α/β/α sandwich-like domain characteristic of the ribokinase-like superfamily, and a second domain composed of four-stranded β sheets. Structural comparison analysis suggested that residues G236, A237, G238, and D239 could be critical for ATP catalysis and substrate binding of PfkB. Our current work provides new insights into understanding the mechanism of the glycolysis in M. marinum.

An update of the molecular mechanisms underlying doxorubicin plus trastuzumab induced cardiotoxicity

Cardiotoxicity is a major side effect of the chemotherapeutic drug doxorubicin (Dox), which is further exacerbated when it is combined with trastuzumab, a standard care approach for Human Epidermal growth factor Receptor-type 2 (HER2) positive cancer patients. However, the molecular mechanisms of the underlying cardiotoxicity of this combination are still mostly elusive. Increased oxidative stress, impaired energetic substrate uses and topoisomerase IIB inhibition are among the biological processes proposed to explain Dox-induced cardiomyocyte dysfunction. Since cardiomyocytes express HER2, trastuzumab can also damage these cells by interfering with neuroregulin-1 signaling and mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/Akt and focal adhesion kinase (FAK)-dependent pathways. Nevertheless, Dox and trastuzumab target other cardiac cell types, such as endothelial cells, fibroblasts, cardiac progenitor cells and leukocytes, which can contribute to the clinical cardiotoxicity observed. This review aims to summarize the current knowledge on the cardiac signaling pathways modulated by these two antineoplastic drugs highly used in the management of breast cancer, not only focusing on cardiomyocytes but also to broaden the knowledge of the potential impact on other cells found in the heart.

Neuregulins: protective and reparative growth factors in multiple forms of cardiovascular disease

Neuregulins (NRGs) are protein ligands that act through ErbB receptor tyrosine kinases to regulate tissue morphogenesis, plasticity, and adaptive responses to physiologic needs in multiple tissues, including the heart and circulatory system. The role of NRG/ErbB signaling in cardiovascular biology, and how it responds to physiologic and pathologic stresses is a rapidly evolving field. While initial concepts focused on the role that NRG may play in regulating cardiac myocyte responses, including cell survival, growth, adaptation to stress, and proliferation, emerging data support a broader role for NRGs in the regulation of metabolism, inflammation, and fibrosis in response to injury. The constellation of effects modulated by NRGs may account for the findings that two distinct forms of recombinant NRG-1 have beneficial effects on cardiac function in humans with systolic heart failure. NRG-4 has recently emerged as an adipokine with similar potential to regulate cardiovascular responses to inflammation and injury. Beyond systolic heart failure, NRGs appear to have beneficial effects in diastolic heart failure, prevention of atherosclerosis, preventing adverse effects on diabetes on the heart and vasculature, including atherosclerosis, as well as the cardiac dysfunction associated with sepsis. Collectively, this literature supports the further examination of how this developmentally critical signaling system functions and how it might be leveraged to treat cardiovascular disease.

WY14643 improves left ventricular myocardial mitochondrial and systolic functions in obese rats under chronic persistent hypoxia via the PPARα pathway

AIMS

Peroxisome proliferator-activated receptor (PPAR) α, a key regulator of lipid metabolism, plays a role in maintaining the homeostasis of myocardial energy metabolism. Both hypoxia and obesity inhibit the expression of PPARα in the myocardium. In this study, we verified the inhibitory effects of hypoxia and obesity on PPARα and examined whether WY14643 (4-chloro-6-(2,3-xylidino)-2-pyrimidinylthioacetic acid), an agonist of PPARα, ameliorates myocardial mitochondrial dysfunction and protects cardiac function in obese rats under chronic persistent hypoxia.

MAIN METHODS

Sprague-Dawley rats were randomly divided into six groups: a control group (normal chow diet, normal oxygen), a high-fat diet (HFD) group (normal oxygen), a chronic persistent hypoxia normal chow diet group, a chronic persistent hypoxia HFD group, a chronic persistent hypoxia HFD group with WY14643 treatment, and a chronic persistent hypoxia HFD group with vehicle treatment.

KEY FINDINGS

Hypoxia and obesity increased myocardial lipid accumulation, mitochondrial dysfunction, and left ventricular systolic dysfunction. Myocardial lipid metabolism-related genes, including those encoding PPARα, PPARγ coactivator 1α (PGC1α), and carnitine palmitoyl transferase 1α (CPT1α), were downregulated, while acetyl-CoA carboxylase 2 (ACC2) was upregulated under a combination of hypoxia and obesity. WY14643 upregulated PPARα, PGC1α, and CPT1α, and downregulated ACC2. WY14643 alleviated hypoxia- and obesity-induced myocardial lipid accumulation and improved mitochondrial and left ventricular systolic functions.

SIGNIFICANCE

WY14643 improved myocardial mitochondrial and left ventricular systolic functions in obese rats under chronic persistent hypoxia. Thus, WY14643 possibly exerts its effects by regulating the PPARα pathway and shows potential as a therapeutic target for cardiovascular diseases associated with obesity and hypoxia.

One year of exercise training promotes distinct adaptations in right and left ventricle of female Sprague-Dawley rats

Aerobic exercise training induces a unique cardioprotective phenotype, but it is becoming clear that it does not promote the same structural, functional, and molecular adaptations in both ventricles. In the present study, we aimed to better characterize and compare the molecular pathways involved in the exercise-induced remodeling of both ventricles. Female Sprague-Dawley rats were randomly assigned to control and exercise groups. Animals in the exercise group were submitted to low-intensity treadmill exercise for 54 weeks. After the experimental period, biventricular hemodynamic analysis was performed and right and left ventricles were harvested for morphological and biochemical analyses. Data showed that long-term low-intensity exercise training improves cardiac function, especially left ventricular diastolic function; however, the expression of connexin-43, CCAAT-enhancer binding protein β, and c-kit did not change in none of the ventricles. In the right ventricle, long-term exercise training induced an increase of manganese superoxide dismutase and sirtuin 3 protein expression, suggestive of improved antioxidant capacity. Our results also support that long-term aerobic exercise training imposes greater metabolic remodeling to the right ventricle, mainly by increasing mitochondrial ability to produce ATP, with no association to estrogen-related receptor α regulation.

Early moderate exercise benefits myocardial infarction healing via improvement of inflammation and ventricular remodelling in rats

Thus far, the cellular and molecular mechanisms related to early (especially within 24 hours after acute myocardial infarct (MI)) exercise‐mediated beneficial effects on MI have not yet been thoroughly established. In the present study, we demonstrated that acute MI rats that underwent early moderate exercise training beginning one day after MI showed no increase in mortality and displayed significant improvements in MI healing and ventricular remodelling, including an improvement in cardiac function, a decrease in infarct size, cardiomyocyte apoptosis, cardiac fibrosis and cardiomyocyte hypertrophy, and an increase in myocardial angiogenesis, left ventricular wall thickness and the number of cardiac telocytes in the border zone. Integrated miRNA‐mRNA profiling analysis performed by the ingenuity pathway analysis system revealed that the inhibition of the TGFB1 regulatory network, activation of leucocytes and migration of leucocytes into the infarct zone comprise the molecular mechanism underlying early moderate exercise‐mediated improvements in cardiac fibrosis and the pathological inflammatory response. The findings of the present study demonstrate that early moderate exercise training beginning one day after MI is safe and leads to significantly enhanced MI healing and ventricular remodelling. Understanding the mechanism behind the positive effects of this early training protocol will help us to further tailor suitable cardiac rehabilitation programmes for humans.

AMPK: a balancer of the renin-angiotensin system

The renin-angiotensin system (RAS) is undisputedly well-studied as one of the oldest and most critical regulators for arterial blood pressure, fluid volume, as well as renal function. In recent studies, RAS has also been implicated in the development of obesity, diabetes, hyperlipidemia, and other diseases, and also involved in the regulation of several signaling pathways such as proliferation, apoptosis and autophagy, and insulin resistance. AMP-activated protein kinase (AMPK), an essential cellular energy sensor, has also been discovered to be involved in these diseases and cellular pathways. This would imply a connection between the RAS and AMPK. Therefore, this review serves to draw attention to the cross-talk between RAS and AMPK, then summering the most recent literature which highlights AMPK as a point of balance between physiological and pathological functions of the RAS.

Enhancing cardiac glycolysis causes an increase in PDK4 content in response to short-term high-fat diet

The healthy heart has a dynamic capacity to respond and adapt to changes in nutrient availability. Metabolic inflexibility, such as occurs with diabetes, increases cardiac reliance on fatty acids to meet energetic demands, and this results in deleterious effects, including mitochondrial dysfunction, that contribute to pathophysiology. Enhancing glucose usage may mitigate metabolic inflexibility and be advantageous under such conditions. Here, we sought to identify how mitochondrial function and cardiac metabolism are affected in a transgenic mouse model of enhanced cardiac glycolysis (Glyco^Hi) basally and following a short-term (7-day) high-fat diet (HFD). Glyco^Hi mice constitutively express an active form of phosphofructokinase-2, resulting in elevated levels of the PFK-1 allosteric activator fructose 2,6-bisphosphate. We report that basally Glyco^Hi mitochondria exhibit augmented pyruvate-supported respiration relative to fatty acids. Nevertheless, both WT and Glyco^Hi mitochondria had a similar shift toward increased rates of fatty acid-supported respiration following HFD. Metabolic profiling by GC-MS revealed distinct features based on both genotype and diet, with a unique increase in branched-chain amino acids in the Glyco^Hi HFD group. Targeted quantitative proteomics analysis also supported both genotype- and diet-dependent changes in protein expression and uncovered an enhanced expression of pyruvate dehydrogenase kinase 4 (PDK4) in the Glyco^Hi HFD group. These results support a newly identified mechanism whereby the levels of fructose 2,6-bisphosphate promote mitochondrial PDK4 levels and identify a secondary adaptive response that prevents excessive mitochondrial pyruvate oxidation when glycolysis is sustained after a high-fat dietary challenge.

Pyridostigmine regulates glucose metabolism and mitochondrial homeostasis to reduce myocardial vulnerability to injury in diabetic mice

Diabetic patients are more susceptible to myocardial ischemia damage than nondiabetic patients, with worse clinical outcomes and greater mortality. The mechanism may be related to glucose metabolism, mitochondrial homeostasis, and oxidative stress. Pyridostigmine may improve vagal activity to protect cardiac function in cardiovascular diseases. Researchers have not determined whether pyridostigmine regulates glucose metabolism and mitochondrial homeostasis to reduce myocardial vulnerability to injury in diabetic mice. In the present study, autonomic imbalance, myocardial damage, mitochondrial dysfunction, and oxidative stress were exacerbated in isoproterenol-stimulated diabetic mice, revealing the myocardial vulnerability of diabetic mice to injury compared with mice with diabetes or exposed to isoproterenol alone. Compared with normal mice, the expression of glucose transporters (GLUT)1/4 phosphofructokinase (PFK) FB3, and pyruvate kinase isoform (PKM) was decreased in diabetic mice, but increased in isoproterenol-stimulated normal mice. Following exposure to isoproterenol, the expression of (GLUT)1/4 phosphofructokinase (PFK) FB3, and PKM decreased in diabetic mice compared with normal mice. The downregulation of SIRT3/AMPK and IRS-1/Akt in isoproterenol-stimulated diabetic mice was exacerbated compared with that in diabetic mice or isoproterenol-stimulated normal mice. Pyridostigmine improved vagus activity, increased GLUT1/4, PFKFB3, and PKM expression, and ameliorated mitochondrial dysfunction and oxidative stress to reduce myocardial damage in isoproterenol-stimulated diabetic mice. Based on these results, it was found that pyridostigmine may reduce myocardial vulnerability to injury via the SIRT3/AMPK and IRS-1/Akt pathways in diabetic mice with isoproterenol-induced myocardial damage. This study may provide a potential therapeutic target for myocardial damage in diabetic patients.

Hypoxia-induced reprogramming of the cardiac phenotype in American alligators (Alligator mississippiensis) revealed by quantitative proteomics

Hypoxic exposure during development can have a profound influence on offspring physiology, including cardiac dysfunction, yet many reptile embryos naturally experience periods of hypoxia in buried nests. American alligators experimentally exposed to developmental hypoxia demonstrate morphological and functional changes to the heart that persist into later life stages; however, the molecular bases of these changes remain unknown. We tested if targeted and persistent changes in steady-state protein expression underlie this hypoxic heart phenotype, using isobaric tags for relative and absolute quantitation (iTRAQ) proteomics. Alligator eggs were reared under normoxia or 10% hypoxia, then either sampled (embryo) or returned to normoxia for 2 years (juvenile). Three salient findings emerge from the integrated analysis of the 145 differentially expressed proteins in hypoxia-reared animals: (1) significant protein-protein interaction networks were identified only in up-regulated proteins, indicating that the effects of developmental hypoxia are stimulatory and directed; (2) the up-regulated proteins substantially enriched processes related to protein turnover, cellular organization, and metabolic pathways, supporting increased resource allocation towards building and maintaining a higher functioning heart; and (3) the juvenile cardiac proteome retained many of the signature changes observed in embryonic hearts, supporting long-term reprogramming of cardiac myocytes induced by hypoxia during critical periods of development.

Effects of Exercise to Improve Cardiovascular Health

Obesity is a complex disease that affects whole body metabolism and is associated with an increased risk of cardiovascular disease (CVD) and Type 2 diabetes (T2D). Physical exercise results in numerous health benefits and is an important tool to combat obesity and its co-morbidities, including cardiovascular disease. Exercise prevents both the onset and development of cardiovascular disease and is an important therapeutic tool to improve outcomes for patients with cardiovascular disease. Some benefits of exercise include enhanced mitochondrial function, restoration and improvement of vasculature, and the release of myokines from skeletal muscle that preserve or augment cardiovascular function. In this review we will discuss the mechanisms through which exercise promotes cardiovascular health.

Exercise Training Impacts Cardiac Mitochondrial Proteome Remodeling in Murine Urothelial Carcinoma

Cardiac dysfunction secondary to cancer may exert a negative impact in patients’ tolerance to therapeutics, quality of life, and survival. The aim of this study was to evaluate the potential therapeutic effect of exercise training on the heart in the setting of cancer, after diagnosis. Thus, the molecular pathways harbored in heart mitochondria from a murine model of chemically-induced urothelial carcinoma submitted to 8-weeks of high intensity treadmill exercise were characterized using mass spectrometry-based proteomics. Data highlight the protective effects of high intensity exercise training in preventing left ventricle diastolic dysfunction, fibrosis, and structural derangement observed in tumor-bearing mice. At the mitochondrial level, exercise training counteracted the lower ability to produce ATP observed in the heart of animals with urothelial carcinoma and induced the up-regulation of fatty acid oxidation and down-regulation of the biological process “cardiac morphogenesis”. Taken together, our data support the prescription of exercise training after cancer diagnosis for the management of disease-related cardiac dysfunction.