Small Molecule Activators of Mitochondrial Fusion Prevent Congenital Heart Defects Induced by Maternal Diabetes

Diabetes and Early Development: Epigenetics, Biological Stress, and Aging

Pregestational diabetes, either type 1 or type 2 diabetes, induces structural birth defects including neural tube defects and congenital heart defects in human fetuses. Rodent models of type 1 and type 2 diabetic embryopathy have been established and faithfully mimic human conditions. Hyperglycemia of maternal diabetes triggers oxidative stress in the developing neuroepithelium and the embryonic heart leading to the activation of proapoptotic kinases and excessive cell death. Oxidative stress also activates the unfolded protein response and endoplasmic reticulum stress. Hyperglycemia alters epigenetic landscapes by suppressing histone deacetylation, perturbing microRNA (miRNA) expression, and increasing DNA methylation. At cellular levels, besides the induction of cell apoptosis, hyperglycemia suppresses cell proliferation and induces premature senescence. Stress signaling elicited by maternal diabetes disrupts cellular organelle homeostasis leading to mitochondrial dysfunction, mitochondrial dynamic alteration, and autophagy impairment. Blocking oxidative stress, kinase activation, and cellular senescence ameliorates diabetic embryopathy. Deleting the mir200c gene or restoring mir322 expression abolishes maternal diabetes hyperglycemia-induced senescence and cellular stress, respectively. Both the autophagy activator trehalose and the senomorphic rapamycin can alleviate diabetic embryopathy. Thus, targeting cellular stress, miRNAs, senescence, or restoring autophagy or mitochondrial fusion is a promising approach to prevent poorly controlled maternal diabetes-induced structural birth defects. In this review, we summarize the causal events in diabetic embryopathy and propose preventions for this pathological condition. · Maternal diabetes induces structural birth defects.. · Kinase signaling and cellular organelle stress are critically involved in neural tube defects.. · Maternal diabetes increases DNA methylation and suppresses developmental gene expression.. · Cellular apoptosis and senescence are induced by maternal diabetes in the neuroepithelium.. · microRNAs disrupt mitochondrial fusion leading to congenital heart diseases in diabetic pregnancy..

Genetic and Environmental Contributors To Congenital Heart Disease

Purpose of Review

Paradigms surrounding congenital heart disease (CHD) etiology represent an evolving area of study. Traditionally, genetic causes of CHD have been classified into chromosomal abnormalities, copy number variation, and single-gene disorders, while environmental contributors include external and intrinsic maternal factors that impair cardiac development. Here, we summarize established causes of CHD and highlight emerging insights into CHD pathogenesis that may inform future treatment options.

Recent Findings

Recent advancements in next-generation sequencing technologies have uncovered novel genetic etiologies underlying CHD including oligogenic inheritance and pathogenic noncoding variation. In addition, industrialization and transformation of society has introduced new environmental risk factors that may contribute to CHD. Further, mechanistic insight into both genetic and environmental factors underlying CHD has led to discovery of novel therapeutic strategies.

Summary

New methodologies have greatly improved our comprehension of the heterogeneous mechanisms underlying CHD, catalyzing the discovery of effective therapeutic strategies to reduce CHD incidence.

Cytochrome P450 2E1 aggravates DXR-induced myocardial injury through imbalanced mitochondrial OPA1

BACKGROUND

Cytochrome P450 2E1 (CYP2E1), a drug metabolism enzyme, is linked to multiple pathophysiological states in the myocardium and may act as a sensor of heart diseases. However, the exact mechanisms of CYP2E1 in myocardial injury, particularly in chemotherapeutic agent-induced myocardial damage such as doxorubicin-induced cardiotoxicity, remain unclear.

METHODS

Using multiple animal models of cardiomyopathy and heart failure, we observed CYP2E1 expression in myocardial mitochondria. Myocardium-specific CYP2E1 overexpression and knockout rat models were employed to study its effects on myocardial injury, assessed via echocardiography and histopathology. Mechanistic insights were derived from transcriptome analysis, mass spectrometry, co-immunoprecipitation, signal transduction analysis, and molecular biology techniques.

RESULTS

CYP2E1 overexpression accelerated, while CYP2E1 knockout inhibited, myocardial injury in DXR-induced cardiomyopathy and isoprenaline-induced hypertrophic cardiomyopathy. Mechanistically, CYP2E1 was upregulated specifically in myocardial mitochondria during heart disease. This upregulation resulted in mitochondrial fragmentation and dysfunction under DXR-induced stress. CYP2E1 interacted with optic atrophy 1 (OPA1) in the inner mitochondrial membrane, leading to an imbalance between long and short OPA1 isoforms.

CONCLUSIONS

CYP2E1 disrupts OPA1-mediated mitochondrial dynamics, causing mitochondrial fragmentation and apoptosis, which aggravate myocardial injury. Targeting CYP2E1 may offer a therapeutic strategy to mitigate myocardial damage, particularly in chemotherapeutic drug-induced cardiotoxicity.

Congenital Heart Diseases and Neurodevelopmental Disorders: New Insights Through the DOHaD Hypothesis

Congenital heart disease (CHD) is the primary cause of birth defects, affecting 9 per 1,000 live births. Up to 50% of them will develop neurodevelopmental disorders, two-thirds of which being unexplained by postnatal risk factors. Recent advances suggest a triangular relationship between the placenta and the fetal heart and brain in CHD, consistent with the Developmental Origins of Health and Disease hypothesis, ie, the in utero programming of early and later-in-life noncommunicable cardiometabolic and mental diseases. The current review provides comprehensive evidence of placental, cardiac, and cerebral tissues interactions, and details how placental dysregulation may affect vasculogenesis, angiogenesis and neural tube closure, hemodynamics, energy supply, endocrine function, and epigenetic regulation of the developing heart and brain. Future studies should include placental research, since identifying placental biomarkers would allow early identification of CHD infants at higher risk for neurodevelopmental disorders, leading to targeted preventive personalized interventions.