Project description:Dilated cardiomyopathy (DCM) constitutes a major cause of heart failure, characterized by high mortality rates and a limited availability of effective therapeutic options. A substantial body of evidence indicates that mutations in the Nexilin (NEXN) gene are significant pathogenic contributors to DCM, and we have developed a NEXN-deficient human cardiac myocyte model that faithfully replicated the pathophysiological characteristics of DCM. This model addressed the limitations associated with interspecies physiological differences and was highly suitable for further investigation into the underlying pathogenesis. We demonstrated that NEXN was one of the important components in maintaining the structure and function of cardiomyocyte JMCs, and played a key regulatory role in maintaining the normal excitation-contraction coupling of cardiomyocytes. Meanwhile, NEXN also played a critical role in maintaining the normal energy metabolism of cardiomyocytes, and the loss of its function would lead to DCM. Furthermore, Levo-carnitine and SERCA2a Activator 1 were identified as promising therapeutic agents for the treatment of DCM. Our finding reveals a critical regulatory role of NEXN in JMCs and mitochondria to prevent the development of DCM.
Project description:RNA-Seq results of adult mouse cardiomyocytes with Jmjd4 knockout and neonatal rat cardiomyocytes with Jmjd4 knockdown. To investigate the role of Jmjd4 in dilated cardiomyopathy, we performed gene expression profiling with RNA-Seq results from heart samples of MCM+ Jmjd4f/f and control Jmjd4f/f mice, as well as neonatal rat ventricuar cardiomyocytes (NRVCs) treated with si-Jmjd4 and si-NC control.
Project description:Mutation on A-type lamins encoding gene can lead to a wide-range of diseases called laminopathies, including dilated cardiomyopathy. Nuclear lamins are integral to a physical continuum connecting the extracellular environment and the nuclear interior, playing a crucial role in load-bearing tissues like the heart to preserve mechanical integrity and genome stability. To investigate the impact of the LMNA p.H222P mutation on gene expression, we conducteed bulk RNA-seq in hiPSCs-derived cardiomyocytes and mouse cardiomyocytes, both carrying this mutation. Our results reveal that the LMNA p.H222P mutation leads to dysregulated gene expression, which may contribute to LMNA cardiomyopathy pathogenesis.
Project description:Cardiac metabolism is deranged in heart failure, but underlying mechanisms remain unclear. Lysine demethylase 8 (Kdm8) represses gene expression in the embryo and controls metabolism in cancer. However, its function in cardiac homeostasis is unknown. We show that Kdm8 maintains a mitochondrial gene network active by repressing Tbx15 to prevent dilated cardiomyopathy leading to lethal heart failure. Deletion of Kdm8 in mouse cardiomyocytes increased H3K36me2 with activation of Tbx15 and repression of target genes in the NAD+ pathway before dilated cardiomyopathy initiates. Moreover, NAD+ supplementation prevented dilated cardiomyopathy in Kdm8 mutant mice and TBX15 overexpression blunted NAD+-activated cardiomyocyte respiration. Furthermore, KDM8 was downregulated in human hearts affected by dilated cardiomyopathy and higher TBX15 expression defines a subgroup of affected hearts with the strongest downregulation of genes encoding mitochondrial proteins. Thus, KDM8 represses TBX15 to maintain cardiac metabolism. Our results suggest that epigenetic dysregulation of metabolic gene networks initiates myocardium deterioration towards heart failure and could underlie heterogeneity of dilated cardiomyopathy.
Project description:Cardiac metabolism is deranged in heart failure, but underlying mechanisms remain unclear. Lysine demethylase 8 (Kdm8) represses gene expression in the embryo and controls metabolism in cancer. However, its function in cardiac homeostasis is unknown. We show that Kdm8 maintains a mitochondrial gene network active by repressing Tbx15 to prevent dilated cardiomyopathy leading to lethal heart failure. Deletion of Kdm8 in mouse cardiomyocytes increased H3K36me2 with activation of Tbx15 and repression of target genes in the NAD+ pathway before dilated cardiomyopathy initiates. Moreover, NAD+ supplementation prevented dilated cardiomyopathy in Kdm8 mutant mice and TBX15 overexpression blunted NAD+-activated cardiomyocyte respiration. Furthermore, KDM8 was downregulated in human hearts affected by dilated cardiomyopathy and higher TBX15 expression defines a subgroup of affected hearts with the strongest downregulation of genes encoding mitochondrial proteins. Thus, KDM8 represses TBX15 to maintain cardiac metabolism. Our results suggest that epigenetic dysregulation of metabolic gene networks initiates myocardium deterioration towards heart failure and could underlie heterogeneity of dilated cardiomyopathy.
Project description:End stage heart failure due to ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM) have similar characteristics, enlargement of the ventricles, relatively thin-walled ventricle, which leads to a limited contraction force and blood loading. Nevertheless, the response for present therapeutics is very variable and the prognosis is still very bad for ICM and DCM in general. Thus, the ability to differentiate the etiologies of heart failure based structural and physiological changes of the heart would be a step forward to enhance the specificity and the success of given therapy.