Cardiomyocyte Apoptosis In Mice Research Articles

Lin28a protects against postinfarction myocardial remodeling and dysfunction through Sirt1 activation and autophagy enhancement

BackgroundMyocardial remodeling and cardiac dysfunction prevention may represent a therapeutic approach to reduce mortality in patients with myocardial infarction (MI). We investigated the effects of Lin28a in experimental MI models, as well as the mechanisms underlying these effects. MethodsLeft anterior descending (LAD) coronary artery ligation was used to construct an MI-induced injury model. Neonatal cardiomyocytes were isolated and cultured to investigate the mechanisms underlying the protective effects of Lin28a against MI-induced injury. ResultsLin28a significantly inhibited left ventricular remodeling and cardiac dysfunction after MI, as demonstrated via echocardiography and hemodynamic measurements. Lin28a reduced cardiac enzyme and inflammatory marker release in mice subjected to MI-induced injury. The mechanisms underlying the protective effects of Lin28a against MI-induced injury were associated with autophagy enhancements and apoptosis inhibition. Consistent with these findings, Lin28a knockdown aggravated cardiac remodeling and dysfunction after MI-induced injury. Lin28a knockdown also inhibited cardiomyocyte autophagy and increased cardiomyocyte apoptosis in mice subjected to MI-induced injury. Interestingly, Sirt1 knockdown abolished the protective effects of Lin28a against cardiac remodeling and dysfunction after MI, and Lin28a failed to increase the numbers of GFP-LC3-positive punctae and decrease aggresome and p62 accumulation in Sirt1-knockdown neonatal cardiomyocytes subjected to hypoxia-induced injury. ConclusionsLin28a inhibits cardiac remodeling, improves cardiac function, and reduces cardiac enzyme and inflammatory marker release after MI. Lin28a also up-regulates cardiomyocyte autophagy and inhibits cardiomyocyte apoptosis through Sirt1 activation.

CCN1 enables Fas ligand-induced apoptosis in cardiomyoblast H9c2 cells by disrupting caspase inhibitor XIAP

Cell proliferation from pre-existing cardiomyocytes is a major source of cells for normal mammalian myocardial renewal or for regeneration after myocardial injury. These proliferative cardiomyocytes may act differently from the postmitotic cardiomyocytes in a stressed heart. Extracellular matrix molecule CCN1 is produced to promote Fas ligand (FasL)-induced cardiomyocyte apoptosis in mice with stress-induced cardiac injury. We aimed to investigate the effect of CCN1 on the proliferative cardiomyocytes. We used rat embryonic cardiomyoblast H9c2 cells to study the cardiotoxicity of CCN1. We found that FasL dose-dependently increased the X-linked inhibitor of apoptosis protein (XIAP) levels to prevent the progression of apoptosis in H9c2 cells. CCN1, though it did not induce apoptosis by itself, sensitized H9c2 cells to FasL-induced apoptosis. CCN1 functions by engaging its cell-surface receptor integrin α6β1 and elevating reactive oxygen species levels, which leads to mitogen-activated protein kinase p38 activation, cytosolic Bax translocation to mitochondria, and the release of mitochondrial Smac and HtrA2 to cytosol. These elevated cytosolic Smac and HtrA2 dismantle the inhibition of XIAP, thereby facilitating the activation of caspase-3 and the apoptosis-induced by FasL. In summary, we demonstrated a novel mechanism underlying the resistance of cardiomyoblasts to FasL-induced apoptosis, and the pro-apoptotic function of CCN1 by disrupting this resistance.

Correction: Klotho Suppresses Cardiomyocyte Apoptosis in Mice with Stress-Induced Cardiac Injury via Downregulation of Endoplasmic Reticulum Stress

Correction: Klotho Suppresses Cardiomyocyte Apoptosis in Mice with Stress-Induced Cardiac Injury via Downregulation of Endoplasmic Reticulum Stress

Klotho Suppresses Cardiomyocyte Apoptosis in Mice with Stress-Induced Cardiac Injury via Downregulation of Endoplasmic Reticulum Stress

Cardiomyocyte apoptosis is a common pathological alteration in heart disease which results in systolic dysfunction or sudden death. Klotho is a novel anti-aging hormone. We tested the effects of klotho on cell apoptosis in isoproterenol-treated cardiomyocytes. In BALB/c mice, cardiac injury was induced by subcutaneous injection of isoproterenol (5mg/kg, for 9days, sc). Klotho (0.01 mg/kg, every other day for 4days, ip) was administered to determine the changes in isoproterenol-induced apoptosis. Mouse heart was harvested at day 2, day 5, and day 9 after isoproterenol injection. Isoproterenol induced cardiac apoptosis and endoplasmic reticulum (ER) stress in a time-dependent manner. However, klotho partly reversed isoproterenol-induced cardiac apoptosis and ER stress. These same effects were observed in cultured cardiomyocytes. Furthermore, the results also showed that SB203580, a p38 inhibitor, and SP600125, a c-Jun NH2-terminal kinase (JNK) inhibitor, reduced cardiomyocyte apoptosis and ER stress, however, klotho suppressed isoproterenol-induced activation of p38 and JNK. Taken together, these results indicated that cardioprotection by klotho was related to the attenuation of ER stress and ER stress-induced apoptosis, at least partly, through suppressing activation of the p38 and JNK pathway.

Extracellular matrix protein CCN1 regulates cardiomyocyte apoptosis in mice with stress-induced cardiac injury

Expression of extracellular matrix protein CCN1 is induced in end-stage ischaemic cardiomyopathy in humans, and after cardiac ischaemia and reperfusion in experimental animal models. Despite its well-documented angiogenic activities, CCN1 increases the cytotoxicities of the tumour necrosis factor family cytokines, which promotes apoptosis in fibroblasts. We aimed to determine the physiological function of CCN1 in an injured heart. To assess the function of CCN1 in vivo, knock-in mice carrying the apoptosis-defective mutant allele Ccn1-dm were tested in an isoproterenol (ISO)-induced myocardial injury model (100 mg/kg/day of sc injected ISO for 5 days). Compared with wild-type mice, Ccn1(dm/dm) mice were remarkably resistant to ISO-induced cardiac injury; they showed no post-treatment cardiomyocyte apoptosis or myocardial tissue damage. ISO cardiotoxicity was dependent on Fas ligand (FasL) and its downstream signalling. Using primary cultures of cardiomyocytes isolated from rats, we demonstrated that CCN1 sensitized FasL-mediated apoptosis by engaging its cell-surface receptor integrin α6β1 and up-regulating intracellular reactive oxygen species (ROS), which activated mitogen-activated protein kinase p38, and increased cell-surface Fas expression. CCN1 is a critical pathophysiological regulator that mediates cardiomyocyte apoptosis during work-overload-induced cardiac injury. CCN1 increases cellular susceptibility to Fas-induced apoptosis by increasing ROS and cell-surface Fas expression.

Resveratrol attenuates doxorubicin-induced cardiomyocyte apoptosis in mice through SIRT1-mediated deacetylation of p53

Doxorubicin (DOX) is an anthracycline drug with a wide spectrum of clinical antineoplastic activity, but increased apoptosis has been implicated in its cardiotoxicity. Resveratrol (RES) was shown to harbour major health benefits in diseases associated with oxidative stress. In this study, we aimed to determine the effect of RES on DOX-induced myocardial apoptosis in mice. Male Balb/c mice were randomized to one of the following four treatments: saline, RES, DOX, or RES plus DOX (10 mice in each group). DOX treatment markedly depressed cardiac function, decreased the heart weight, the body weight, and the ratio of heart weight to body weight, but inversely increased the level of protein carbonyl, malondialdehyde, and serum lactate dehydrogenase, and induced mitochondrial cytochrome c release and cardiomyocyte apoptosis. However, these effects of DOX were ameliorated by its combination with RES. Further studies with a co-immunoprecipitation assay revealed an interaction between p53 and Sirtuin 1 (SIRT1). It was found by western blot and electrophoretic mobility shift assay that DOX treatment increased p53 protein acetylation and cytochrome c release from mitochondria, activated p53 binding at the Bax promoter, and up-regulated Bax expression, but supplementation with RES could weaken all these effects. The protective effect of RES against DOX-induced cardiomyocyte apoptosis is associated with the up-regulation of SIRT1-mediated p53 deacetylation.

The defects in development and apoptosis of cardiomyocytes in mice lacking the transcriptional factor Pax-8

BackgroudCardiac-specific deletion of ALK3 is lethal in mid-gestation with ventricular septum malformations (VSM). This study was designed to define the Pax-8's role in heart development and cardiomyocyte apoptosis. MethodsPathologic changes in the hearts of Pax-8 or ALK3 knockout and wild type control mice were determined by light and electron microscopy. Analysis of cardiomyocyte apoptosis was performed by TUNEL. The effect of Pax-8 gene deficiency on caspase-3 activity was examined after transfecting Pax-8 siRNA into cultured myoblast cell line. ResultsMice with ALK3 or Pax-8 gene knockout but not wild type control animals showed the development of VSM. Increased cardiomyocyte apoptosis was found in homozygotes. Echocardiography showed that Pax-8 homozygote mice developed malfunction of the heart. Furthermore, the caspase-3 activity was significantly higher in the cells treated with Pax-8 siRNA as compared to those treated with negative control siRNA in H9C2 (2-1) cell line. ConclusionsThe Pax-8 gene may play a crucial role in heart development and regulating cardiocyte apoptosis. Knockout of Pax-8 may exert a similar effect on myocardial morphology and apoptosis as those seen in ALK3 knockouts. Furthermore, the ventricular septum malformations could be partially attributed to accelerated cardiomyocyte apoptosis.

The defects in development and apoptosis of cardiomyocytes in mice lacking the transcriptional factor Pax-8

Objective Cardiac-specific deletion of the receptor IA for the bone morphogenetic protein (BMP), ALK3, by Cre recombinase driven under the alpha-MHC promoter is lethal in mid-gestation with a ventricular septum defect (VSD). This study was designed to define the Pax-8's role in regulation of ALK3 signaling transduction during the interventricular septum development and cardiomyocyte apoptosis. Design and methods Pathologic changes in the hearts of Pax-8 or ALK3 knockout and wild type control mice were determined by light and electron microscopy. Analysis of cardiomyocyte apoptosis was performed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). In addition, high-frequency ultrasound imaging was applied to measure the cardiac dimensions, function, and hemodynamics of homozygote and heterozygote mice of Pax-8. The effect of Pax-8 gene deficiency on caspase-3 activity was examined after transfecting Pax-8 siRNA into cultured myoblast cell line. Results Mice with ALK3 or Pax-8 gene knockout but not wild type control animals showed the development of VSD. Increased cardiomyocyte apoptosis was found in homozygotes. The heterozygote and wild type mice had no or minor changes in apoptosis. Echocardiography showed that Pax-8 homozygote mice developed malfunction of the heart. Furthermore, the caspase-3 activity was significantly higher in the cells treated with Pax-8 siRNA as compared to those treated with negative control siRNA in H9C2 (2-1) cell line. Conclusion The Pax-8 gene may play a crucial role in heart development and regulating cardiomyocyte apoptosis. Knockout of Pax-8 may exert a similar effect on myocardial morphology and apoptosis as those seen in ALK3 knockouts. Furthermore, the ventricular septum defect could be partially attributed to accelerated cardiomyocyte apoptosis.

Cardiotoxicity associated with tyrosine kinase inhibitor sunitinib

Sunitinib, a multitargeted tyrosine-kinase inhibitor, which is approved by both US and European Commission regulatory agencies for clinical use, extends survival of patients with metastatic renal-cell carcinoma and gastrointestinal stromal tumours, but concerns have arisen about its cardiac safety. We therefore assessed the cardiovascular risk associated with sunitinib in patients with metastatic gastrointestinal stromal tumours. We retrospectively reviewed all cardiovascular events in 75 patients with imatinib-resistant, metastatic, gastrointestinal stromal tumours who had been enrolled in a phase I/II trial investigating the efficacy of sunitinib. The composite cardiovascular endpoint was cardiac death, myocardial infarction, and congestive heart failure. We also examined sunitinib's effects on left ventricular ejection fraction (LVEF) and blood pressure. We investigated potential mechanisms of sunitinib-associated cardiac effects by studies in isolated rat cardiomyocytes and in mice. Eight of 75 (11%) patients given repeating cycles of sunitinib in the phase I/II trial had a cardiovascular event, with congestive heart failure recorded in six of 75 (8%). Ten of 36 (28%) patients treated at the approved sunitinib dose had absolute LVEF reductions in ejection fraction (EF) of at least 10%, and seven of 36 (19%) had LVEF reductions of 15 EF% or more. Sunitinib induced increases in mean systolic and diastolic blood pressure, and 35 of 75 (47%) individuals developed hypertension (>150/100 mm Hg). Congestive heart failure and left ventricular dysfunction generally responded to sunitinib being withheld and institution of medical management. Sunitinib caused mitochondrial injury and cardiomyocyte apoptosis in mice and in cultured rat cardiomyocytes. Left ventricular dysfunction might be due, in part, to direct cardiomyocyte toxicity, exacerbated by hypertension. Patients treated with sunitinib should be closely monitored for hypertension and LVEF reduction, especially those with a history of coronary artery disease or cardiac risk factors.

17-Beta-Estradiol increases cardiac remodeling and mortality in mice with myocardial infarction

ObjectivesThis study was designed to examine the effects of estrogen replacement on infarct size, ventricular remodeling, and mortality after myocardial infarction (MI) in mice. BackgroundObservational and clinical studies suggest that the cardiovascular effects of hormone replacement therapy can differ depending on the patient population studied. No prospective studies have examined the effect of estrogen on outcomes following MI. We now examine the effects of estrogen replacement on infarct size, ventricular remodeling, and mortality after MI in mice. MethodsMyocardial infarction was induced by left coronary artery ligation in ovariectomized female mice treated with 17-beta-estradiol (E2) or placebo. At either one day or six weeks after MI, hemodynamic function was assessed, animals were euthanized, and infarct size was determined. Results17-Beta-estradiol–treated mice had smaller infarcts than placebo-treated animals both one day (18% decrease; p < 0.01), and six weeks (14% decrease; p < 0.05) following MI. E2 reduced cardiomyocyte apoptosis as assessed by the terminal deoxynucleotidyl transferase uridine nucleotide end-labeling method (50% reduction, p < 0.05) and caspase 3 activation (33% reduction, p < 0.05). Despite having smaller infarcts, however, left ventricular mass increased more in the E2-treated animals (16% greater; p < 0.01). Left ventricular weight was positively correlated with infarct size in the estrogen-treated animals (R2 = 0.79, p = 0.0001). 17-Beta-estradiol treatment also significantly increased mortality in the infarcted animals (relative risk of death = 2.4; 95% confidence interval 1.2 to 5.3). ConclusionsEstrogen replacement therapy reduces infarct size and cardiomyocyte apoptosis in mice. However, estrogen increased post-MI ventricular remodeling and mortality. Further studies will be necessary to elucidate the mechanisms underlying the complex effects of estrogen observed in the present study.