Myocardial Mitochondrial Biogenesis Research Articles

Abstract 16778: Design of a Pan Heart Failure Gene Therapy by Targeting Telomere-p53 Axis

Introduction: Cardiovascular disease and heart failure is among the top causes of morbidity and mortality worldwide with a critical need for innovative therapies to reverse the course of ventricular dysfunction. We established that heart failure cardiomyocytes exhibit telomere uncapping and shortening, which leads to DNA damage p53 activation and inhibition of mitochondrial biogenesis. Hypothesis: We hypothesize that reprotection of telomeric ends can prevent p53-induced mitochondrial dysfunction and restore cardiac function. Methods: We designed a pan-HF gene therapy (AAV9-modhTERT) - that acts through telomeric reprotection to turn off p53 and restore myocardial mitochondrial biogenesis - and validate safety and efficacy in Ang II and TAC heart failure murine models. Cardiac specificity in human induced pluripotent stem cell derived cardiomyocytes, biodistribution in mice, and dose titration studies on Ang II and TAC mice were performed. Results: One dose of AAV9-modhTERT sufficiently improved ejection fraction by ~20%, prevented cardiac fibrosis and expression of HF biomarkers. Molecularly, AAV9-modTERT blocked DNA damage activation, reversed mitochondrial biogenesis, restored mitochondrial ultrastructure and respiration, and reversed transcriptomic profiles. Conclusions: These preclinical studies demonstrate considerable potential for the first pan-HF single-dose gene therapy that can reverse cardiac function and prevent myocardial remodeling which would be invaluable clinically and an Investigator Initiated Trial (IIT) (NCT05837143) was launched in April 2023.

Effect of exercise on improving myocardial mitochondrial function in decreasing diabetic cardiomyopathy.

Diabetic cardiomyopathy (DCM) is a significant cause of heart failure in patients with diabetes, and its pathogenesis is closely related to myocardial mitochondrial injury and functional disability. Studies have shown that the development of diabetic cardiomyopathy is related to disorders in mitochondrial metabolic substrates, changes in mitochondrial dynamics, an imbalance in mitochondrial Ca2+ regulation, defects in the regulation of microRNAs, and mitochondrial oxidative stress. Physical activity may play a role in resistance to the development of diabetic cardiomyopathy by improving myocardial mitochondrial biogenesis, the level of autophagy and dynamic changes in fusion and division; enhancing the ability to cope with oxidative stress; and optimising the metabolic substrates of the myocardium. This paper puts forward a new idea for further understanding the specific mitochondrial mechanism of the occurrence and development of diabetic cardiomyopathy and clarifying the role of exercise-mediated myocardial mitochondrial changes in the prevention and treatment of diabetic cardiomyopathy. This is expected to provide a new theoretical basis for exercise to reduce diabetic cardiomyopathy symptoms.

Optimal treatment for post-MI heart failure in rats: dapagliflozin first, adding sacubitril-valsartan 2 weeks later.

Based on previous research, both dapagliflozin (DAPA) and sacubitril-valsartan (S/V) improve the prognosis of patients with heart failure (HF). Our study aims to investigate whether the early initiation of DAPA or the combination of DAPA with S/V in different orders would exert a greater protective effect on heart function than that of S/V alone in post-myocardial infarction HF (post-MI HF). Rats were randomized into six groups: (A) Sham; (B) MI; (C) MI + S/V (1st d); (D) MI + DAPA (1st d); (E) MI + S/V (1st d) + DAPA (14th d); (F) MI + DAPA (1st d) + S/V (14th d). The MI model was established in rats via surgical ligation of the left anterior descending coronary artery. Histology, Western blotting, RNA-seq, and other approaches were used to explore the optimal treatment to preserve the heart function in post-MI HF. A daily dose of 1 mg/kg DAPA and 68 mg/kg S/V was administered. The results of our study revealed that DAPA or S/V substantially improved the cardiac structure and function. DAPA and S/V monotherapy resulted in comparable reduction in infarct size, fibrosis, myocardium hypertrophy, and apoptosis. The administration of DAPA followed by S/V results in a superior improvement in heart function in rats with post-MI HF than those in other treatment groups. The administration of DAPA following S/V did not result in any additional improvement in heart function as compared to S/V monotherapy in rats with post-MI HF. Our findings further suggest that the combination of DAPA and S/V should not be administered within 3 days after acute myocardial infarction (AMI), as it resulted in a considerable increase in mortality. Our RNA-Seq data revealed that DAPA treatment after AMI altered the expression of genes related to myocardial mitochondrial biogenesis and oxidative phosphorylation. Our study revealed no notable difference in the cardioprotective effects of singular DAPA or S/V in rats with post-MI HF. Based on our preclinical investigation, the most effective treatment strategy for post-MI HF is the administration of DAPA during the 2 weeks, followed by the addition of S/V to DAPA later. Conversely, adopting a therapeutic scheme whereby S/V was administered first, followed by later addition of DAPA, failed to further improve the cardiac function compared to S/V monotherapy.

Endogenous asymmetric dimethylarginine accumulation contributes to the suppression of myocardial mitochondrial biogenesis in type 2 diabetic rats

BackgroundSuppressed mitochondrial biosynthesis has been reported to be the early signal of mitochondrial dysfunction which contributes to diabetic cardiomyopathy, but the mechanism of mitochondrial biosynthesis suppression is unclear. Nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) is closely related to diabetic cardiovascular complications. This study was to determine whether endogenous ADMA accumulation was involved in the suppression of myocardial mitochondrial biogenesis in diabetic rats and to elucidate the potential mechanism in rat cardiomyocytes.MethodsType 2 diabetic rat model was induced by high-fat feeding plus single intraperitoneal injection of small dose streptozotocin (35 mg/kg). The copy number ratio of mitochondrial gene to nuclear gene was measured to reflect mitochondrial biogenesis. The promoter activity of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and its post-translational modifications were detected by dual-luciferase reporter assay and immunoprecipitation.ResultsMyocardial ADMA content was enhanced and associated with suppressions of myocardial mitochondrial biogenesis and cardiac function in parallel with PGC-1α downregulation and uncoupling protein 2 (UCP2) upregulation in the myocardium of diabetic rats compared with control rats. Similarly, ADMA and its homolog could inhibit myocardial mitochondrial biogenesis and PGC-1α expression, increase UCP2 expression and oxidative stress in vitro and in vivo. Moreover, ADMA also suppressed the promoter activity and PGC-1α expression but boosting its protein acetylation and phosphorylation in rat cardiomyocytes.ConclusionsThese results indicate that endogenous ADMA accumulation contributes to suppression of myocardial mitochondrial biogenesis in type 2 diabetic rats. The underlying mechanisms may be associated with reducing PGC-1α promoter activity and expression but boosting its protein acetylation and phosphorylation.

The effect of apelin-13 on pancreatic islet beta cell mass and myocardial fatty acid and glucose metabolism of experimental type 2 diabetic rats

Apelin, a new identified adipokine, and its G protein–coupled receptor named APJ are widely expressed in various tissues. Apelin has been found to play important roles in the physiopathology of multiple diseases. Our aim is to assess the effect of long-term apelin treatment on serum insulin level and pancreatic islet beta-cell mass in the late stage of type 2 diabetes without hyperinsulinemia and to investigate the role of apelin in myocardial fatty acid and glucose metabolism. In the present study, the high-fat diet fed-streptozotocin-induced experimental type 2 diabetic rats were given once daily intraperitoneal injection of apelin-13 (0.1 μmol/kg) for 10 weeks. We observed that apelin significantly improved serum insulin reduction and reduced hyperglycemia. Histologic analysis showed that long-term apelin treatment significantly increased pancreatic islet beta cell mass. Exogenous apelin failed to change dyslipidaemia of type 2 diabetic rats. Apelin treatment markedly decreased elevated myocardial FFA and glycogen content. Treatment of type 2 diabetic rats with apelin markedly reduced increased gene expressions of the cardiac fatty acid transporter CD36, CPT-1, and Peroxisome proliferator-activated receptor (PPAR)-α. Whereas the gene levels of citrate synthase and peroxisome proliferator–activated receptor γ coactivator 1-α (PGC1-α), a transcriptional coactivator, mediating mitochondrial biogenesis in heart were unaltered in response to exogenous apelin. Taken together, longer-term apelin treatment prevented pancreatic beta-cell loss or failure in experimental type 2 diabetic rats. Apelin can regulate myocardial metabolism. Apelin reduced myocadial fatty acid uptake and oxidation through inhibiting PPAR-α but did not affect myocardial mitochondrial biogenesis in type 2 diabetic rats.

Modulation of cardiac vascular endothelial growth factor and PGC-1α with regular postexercise cold-water immersion of rats.

Myocardial mitochondrial biogenesis and vascular angiogenesis biomarker responses to postexercise cold-water immersion (CWI) have not been reported. Therefore, to determine those cardiac adaptations, adult male Sprague-Dawley rats were divided into three groups: postexercise CWI (CWI; n = 13), exercise only (Ex; n = 12), and untreated control (CON; n = 10). CWI and Ex were trained for 10 wk, 5 sessions/wk, 30-60 min/session. CWI rats were immersed after each session in cold water (15 min at ~12°C). CON remained sedentary. Left ventricle tissue was obtained 48 h after the last exercise session and analyzed for peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), vascular endothelial growth factor (VEGF), and heat shock protein 70 kDa (Hsp70) protein content and mRNA expression levels. In addition, superoxide dismutase activity and mRNA and malondialdehyde levels were evaluated. Ex and CWI induced higher PGC-1α protein content compared with CON (1.8 ± 0.6-fold, P < 0.001), which was significantly higher in CWI than Ex rats (P = 0.01). VEGF protein (4.3 ± 3.7-fold) and mRNA (10.1 ± 1.1-fold) were markedly increased only in CWI (P < 0.001) relative to CON. CWI and Ex augmented cardiac Hsp70 protein to a similar level relative to CON (P < 0.05); however, Hsp70 mRNA increased only in Ex (P = 0.002). No further differences were observed between groups. These results suggest that postexercise CWI may further enhance cardiac oxidative capacity by increasing the angiogenic and mitochondrial biogenic factors. In addition, CWI does not seem to worsen exercise-induced cardioprotection and oxidative stress. NEW & NOTEWORTHY A regular postexercise cold-water immersion for 10 wk of endurance training augmented the myocardial mitochondrial biogenesis and vascular angiogenesis coactivators peroxisome proliferator-activated receptor γ coactivator-1α and vascular endothelial growth factor, respectively. In addition, postexercise cold-water immersion did not attenuate the exercise-induced increase in the cardioprotective biomarker heat shock protein 70 kDa or increase exercise-induced oxidative stress.

PL-020 Establishment of skeletal muscle-specific PGC-1α overexpression model via in vivo local transfection

Objective To establish a skeletal muscle-specific PGC-1α overexpression mouse model via in vivo local transfection.&#x0D; Methods For the PGC-1α in vivo transfection study, the Male FVB/N mice were randomly divided into 2 groups: subject to green fluorescent protein (GFP) transfection (Con-GFP), and subject to PGC-1α in vivo transfection (Con-PGC-1α). Plasmid DNA solution (2.5 mg/ml GFP or 2.7 mg/ml Flag-PGC-1α) were injected into the proximal (6 ml) and distal (6 ml) ends of the muscle belly. Following the injections, electric pulses were applied through 2 stainless steel pin electrodes laid on top of the proximal and distal myotendinous junctions. Then skeletal muscle and myocardium were isolated, and PGC-1α, mtTFA, NF-κB, MnSOD, FNDC5 protein expression were measured with Western blot.&#x0D; Results n skeletal muscle, compared with con-GFP group, the expression of PGC-1α (+125%, p&lt;0.01), mtTFA (+210%, p&lt;0.01), and FNDC5 (+47%, p&lt;0.05) were significantly increased in con-PGC-1α group. However, NF-κB and MnSOD protein level had no change in con-PGC-1α group. In myocardium, compared with con-GFP group, the expression of mtTFA (+130%, p&lt;0.01) and FNDC5 (+55%, p&lt;0.05) were significantly increased in con-PGC-1α group.&#x0D; Conclusions Skeletal muscle-specific PGC-1α overexpression model via in vivo local transfection was established, which was supported by elevated expression of PGC-1α and its downstream FNDC5 and mtTFA. Furthermore, skeletal muscle-specific PGC-1α overexpression induced increase in myocardial mitochondrial biogenesis, while relative mechanism remains to be determined.

The Metabolic Effects of Traditional Chinese Medication Qiliqiangxin on H9C2 Cardiomyocytes

Background/Aims: A traditional Chinese medicine, Qiliqiangxin (QLQX) has been identified to perform protective effects on myocardium energy metabolism in mice with acute myocardial infarction, though the effects of QLQX on myocardial mitochondrial biogenesis under physiological condition is still largely elusive. Methods: H9C2 cells were treated with different concentrations of QLQX (0.25, 0.5, and 1.0 µg/mL) from 6 to 48 hours. Oxidative metabolism and glycolysis were measured by oxygen consumption and extracellular acidification with XF96 analyzer (SeaHorse). Mitochondrial content and ultrastructure were assessed by Mitotracker staining, confocal microscopy, flow cytometry, and transmission electron microscopy. Mitochondrial biogenesis-related genes were measured by qRT-PCR and Western blot. Results: H9C2 cells treated with QLQX exhibited increased glycolysis at earlier time points (6, 12, and 24 hours), while QLQX could enhance oxidative metabolism and mitochondrial uncoupling in H9C2 cells with longer duration of treatment (48 hours). QLQX also increased mitochondrial content and mitochondrial biogenesis-related gene expression levels, including 16sRNA, SSBP1, TWINKLE, TOP1MT and PLOG, with an activation of peroxisome proliferator-activated receptor coactivator 1 alpha (PGC-1α) and its downstream effectors. Silencing PGC-1α could abolish the increased mitochondrial content in H9C2 cells treated with QLQX. Conclusion: Our study is the first to document enhanced metabolism in cardiomyocytes treated with QLQX, which is linked to increased mitochondrial content and mitochondrial biogenesis via activation of PGC-1α.

Cannabidiol Protects against Doxorubicin-Induced Cardiomyopathy by Modulating Mitochondrial Function and Biogenesis.

Doxorubicin (DOX) is a widely used, potent chemotherapeutic agent; however, its clinical application is limited because of its dose-dependent cardiotoxicity. DOX's cardiotoxicity involves increased oxidative/nitrative stress, impaired mitochondrial function in cardiomyocytes/endothelial cells and cell death. Cannabidiol (CBD) is a nonpsychotropic constituent of marijuana, which is well tolerated in humans, with antioxidant, antiinflammatory and recently discovered antitumor properties. We aimed to explore the effects of CBD in a well-established mouse model of DOX-induced cardiomyopathy. DOX-induced cardiomyopathy was characterized by increased myocardial injury (elevated serum creatine kinase and lactate dehydrogenase levels), myocardial oxidative and nitrative stress (decreased total glutathione content and glutathione peroxidase 1 activity, increased lipid peroxidation, 3-nitrotyrosine formation and expression of inducible nitric oxide synthase mRNA), myocardial cell death (apoptotic and poly[ADP]-ribose polymerase 1 [PARP]-dependent) and cardiac dysfunction (decline in ejection fraction and left ventricular fractional shortening). DOX also impaired myocardial mitochondrial biogenesis (decreased mitochondrial copy number, mRNA expression of peroxisome proliferator-activated receptor γ coactivator 1-alpha, peroxisome proliferator-activated receptor alpha, estrogen-related receptor alpha), reduced mitochondrial function (attenuated complex I and II activities) and decreased myocardial expression of uncoupling protein 2 and 3 and medium-chain acyl-CoA dehydrogenase mRNA. Treatment with CBD markedly improved DOX-induced cardiac dysfunction, oxidative/nitrative stress and cell death. CBD also enhanced the DOX-induced impaired cardiac mitochondrial function and biogenesis. These data suggest that CBD may represent a novel cardioprotective strategy against DOX-induced cardiotoxicity, and the above-described effects on mitochondrial function and biogenesis may contribute to its beneficial properties described in numerous other models of tissue injury.

GW25-e2195 Effect of Regulatory Factors of the Myocardial Mitochondrial Biogenesis of Rats after Acute Exhaustive Exercise at Different Time

GW25-e2195 Effect of Regulatory Factors of the Myocardial Mitochondrial Biogenesis of Rats after Acute Exhaustive Exercise at Different Time

GW25-e2196 Effect of Salidroside on the Regulatory Factors of Myocardial Mitochondrial Biogenesis of Rats after Acute Exhaustive Exercise

GW25-e2196 Effect of Salidroside on the Regulatory Factors of Myocardial Mitochondrial Biogenesis of Rats after Acute Exhaustive Exercise

Activation of mitochondrial function and Hb expression in non‐haematopoietic cells by an EPO inducer ameliorates ischaemic diseases in mice

Many organs suffer from ischaemic injuries that reduce their ability to generate sufficient energy, which is required for functional maintenance and repair. Erythropoietin (EPO) ameliorates ischaemic injuries by pleiotropic effects. The aim of this study was to investigate the effect and mechanism of a small molecule EH-201, and found it as a potent EPO inducer and its effect in non-haematopoietic cells for therapeutic potential in ischemic disorders. Mice kidney slices, primary hepatocytes, primary cardiomyocytes and C2C12 myoblasts were treated with EH-201. The effects of this treatment on EPO, Hb expression and mitochondrial biogenesis were analysed. In vivo, doxorubicin-induced cardiomyopathic mice were treated with EH-201. The mice were subjected to an endurance test, electrocardiography and echocardiography, and a histological examination of the isolated hearts was performed. EH-201 was also administered to cisplatin-induced nephropathic mice. In non-haematopoietic cells, EH-201 was potent at inducing EPO. EH-201 also stimulated mitochondrial biogenesis and enhanced the expression of Hb by a mechanism dependent on EPO-mediated signalling. In mechanistic studies, using EPO and EPO receptor-neutralizing antibodies, we confirmed that EH-201 enhances EPO-EPOR autocrine activity. EH-201 robustly increased the endurance performance activity of healthy and cardiomyopathic mice during hypoxic stress, enhanced myocardial mitochondrial biogenesis and Hb expression, and also improved cardiac function. EH-201 ameliorated anaemia and renal dysfunction in nephropathic mice. The enhancement and recovery of cellular functions through the stimulation of mitochondrial activity and Hb production in non-haematopoietic cells by an inducer of endogenous EPO has potential as a therapeutic strategy for ischaemic diseases.

Mitochondrial biogenesis in the metabolic syndrome and cardiovascular disease

The metabolic syndrome is a constellation of metabolic disorders including obesity, hypertension, and insulin resistance, components which are risk factors for the development of diabetes, hypertension, cardiovascular, and renal disease. Pathophysiological abnormalities that contribute to the development of the metabolic syndrome include impaired mitochondrial oxidative phosphorylation and mitochondrial biogenesis, dampened insulin metabolic signaling, endothelial dysfunction, and associated myocardial functional abnormalities. Recent evidence suggests that impaired myocardial mitochondrial biogenesis, fatty acid metabolism, and antioxidant defense mechanisms lead to diminished cardiac substrate flexibility, decreased cardiac energetic efficiency, and diastolic dysfunction. In addition, enhanced activation of the renin-angiotensin-aldosterone system and associated increases in oxidative stress can lead to mitochondrial apoptosis and degradation, altered bioenergetics, and accumulation of lipids in the heart. In addition to impairments in metabolic signaling and oxidative stress, genetic and environmental factors, aging, and hyperglycemia all contribute to reduced mitochondrial biogenesis and mitochondrial dysfunction. These mitochondrial abnormalities can predispose a metabolic cardiomyopathy characterized by diastolic dysfunction. Mitochondrial dysfunction and resulting lipid accumulation in skeletal muscle, liver, and pancreas also impede insulin metabolic signaling and glucose metabolism, ultimately leading to a further increase in mitochondrial dysfunction. Interventions to improve mitochondrial function have been shown to correct insulin metabolic signaling and other metabolic and cardiovascular abnormalities. This review explores mechanisms of mitochondrial dysfunction with a focus on impaired oxidative phosphorylation and mitochondrial biogenesis in the pathophysiology of metabolic heart disease.