Ablation Of ALCAT1Mitigates Hypertrophic Cardiomyopathy Through Effects On Oxidative Stress And Mitophagy

Oxidative stress and mitochondrial dysfunction lead to cardiac dysfunction and heart failure through unknown mechanisms. Cardiolipin (CL) is a mitochondrial phospholipid required for oxidative phosphorylation and cardiac function. Aberrant CL acyl composition and lipid peroxidation are implicated in cardiac dysfunction. ALCAT1is a lysocardiolipin acyltransferase-1that is up-regulated by oxidative stress and age-related metabolic diseases. CL remodeling by ALCAT1leads to synthesis of aberrant CL species commonly found in heart diseases. Here we investigate a role of ALCAT1in hypertrophic cardiomyopathy. The ablation of ALCAT1in mice was evaluated on the regulation of T4-induced cardiomyopathy, ventricular fibrosis, mitochondria damage and mitophagy involved in PINK1. In H9C2cells, we investigated the effect of overexpression of ALCAT1on the oxidative stress, lipid peroxidation, mtDNA copy number, the reorganization of F-actin and cellular morphology. Conversely, the deficiency of ALCAT1in MEF was investigated on the onset of the mitochondria damage induced by oxidative stress. Together, these findings identified ALCAT1as a key enzyme in pathological CL remodeling in cardiac hypertrophy and dysfunction, and and further uncovered the mechanisms from the regulation of oxidative stress, damage of mitochondria and mitophagy, implicating a role of ALCAT1in the etiology of heart diseases.The present studies have found that1. ALCAT1deficiency is sufficient to block thyroid hormones-Induced cardiac hypertrophy in mice, such as the heart to body weight ratio, left ventricular wall thickness, cardiac function, cardiac myocytes size, fibrosis in left ventricular, and the mRNA levels of biomarker of cardiac hypertrophy and Fibrosis, and lipid peroxidation index.2. The protein level of ALCTA1was up-regulated in heart tissue induced by thyroid hormones.3. The deficiency of ALCTA1attenuated the damage of cardiac mitochondria in mice after long term treatment with thyroid hormones.4. The Inactivation of ALCAT1stimulated the protein expression of PINK1and P62in mice heart.5. The deficiency of ALCTA1had no regulatory effect on the activation of Akt pathway in heart after short term thyroid hormones-inducement, but could reverse the down-regulation of Akt pathway after long term thyroid hormones-treatment.6. The stable Vector and ALCAT1gene overexpressing cells have been constructed successful in H9C2.7. In H9C2, the overexpression of ALCAT1induced hypertrophic cell morphology, increased cell volume and proliferation, and inhibited cellular differentiation.8. In H9C2, the overexpression of ALCAT1increased the production of reactive oxygen species (ROS), lipid peroxidation and damage of mtDNA induced by oxidative stress.9. In MEF, the deficiency of ALCTA1induced a reorganization of F-actin, and attenuated the damage of mitochondria induced by oxidative stress.10.ALCTA1was involved in balancing the opposing processes of fusion and fission of mitochondrial network dynamics in H9C2and MEF. The ablation of ALCTA1reduced the mitochondrial fission and fragmentation under oxidative stress.11. The overexpression of ALCAT1reduced the protein expresson of VDAC, and the deficiency of ALCTA1stimulated the protein expresson of VDAC in MEF.12. The ablation of ALCAT1delays the MEF senescence.13.Oxidative stress by ALCAT1in H9c2cells caused severe insulin resistance in signaling pathway in H9C2.14. The overexpression of ALCAT1impaired thyroid hormones-induced phosphorylation of Akt and downstream signaling components in H9C2.Together, using mice model with hyperthyroidism, we investigate the a role of ALCAT1in cardiomyopathy associated with hyperthyroidism, and the regulation of oxidative stress, ultrastructure of mitochondria and mitophagy involved in PINK1, and the upregulation of Akt signaling pathway under pathological conditions et al. To uncover the mechanisms, we investigate the effect of overexpressing of ALCAT1on the cell morphology, proliferation, differentiation, reactive oxygen species (ROS) production, lipid peroxidation, structure of mitochondria, copy number of mtDNA, mitophagy, mitochondrial network and insulin resistance in H9C2and MEF cells. We demonstrate for the first time a key role of ALCAT1in regulating the onset of thyroid hormoneinduced cardiac hypertrophy through oxidative stress and mitophagy.The present findings have additional implications for future studies to uncover molecular mechanisms underlying the causes of other forms of cardiovascular diseases. This newly discovered target gene may yield unique potential target for improving cardiac function in hypertrophy and heart failure.