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Reduced cardiac antioxidant defenses mediate increased susceptibility to workload-induced myocardial injury in males with genetic cardiomyopathy.

ABSTRACT: Ongoing cardiomyocyte injury is a major mechanism in the progression of heart failure, particularly in dystrophic hearts. Due to the poor regenerative capacity of the adult heart, cardiomyocyte death results in the permanent loss of functional myocardium. Understanding the factors contributing to myocyte injury is essential for the development of effective heart failure therapies. As a model of persistent cardiac injury, we examined mice lacking β-sarcoglycan (β-SG), a key component of the dystrophin glycoprotein complex (DGC). The loss of the sarcoglycan complex markedly compromises sarcolemmal integrity in this β-SG-/- model. Our studies aim to characterize the mechanisms underlying dramatic sex differences in susceptibility to cardiac injury in β-SG-/- mice. Male β-SG-/- hearts display significantly greater myocardial injury and death following isoproterenol-induced cardiac stress than female β-SG-/- hearts. This protection of females was independent of ovarian hormones. Male β-SG-/- hearts displayed increased susceptibility to exogenous oxidative stress and were significantly protected by angiotensin II type 1 receptor (AT1R) antagonism. Increasing general antioxidative defenses or increasing the levels of S-nitrosylation both provided protection to the hearts of β-SG-/- male mice. Here we demonstrate that increased susceptibility to oxidative damage leads to an AT1R-mediated amplification of workload-induced myocardial injury in male β-SG-/- mice. Improving oxidative defenses, specifically by increasing S-nitrosylation, provided protection to the male β-SG-/- heart from workload-induced injury. These studies describe a unique susceptibility of the male heart to injury and may contribute to the sex differences in other forms of cardiac injury.

ORGANISM(S): Mus musculus

PROVIDER: GSE249946 | GEO | 2024/03/15

REPOSITORIES: GEO

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Project description:Loss of cardiomyocytes (CMs) following injury can lead to myocardial dysfunction, heart failure (HF) and ultimately death. The limited regenerative ability of the adult human heart after injury, however, poses a significant obstacle to restore cardiac function effectively. While mammalian hearts, including those of mice and humans, do have the potential to regenerate, this capacity is restricted to a narrow window during early stages of life. The molecular mechanisms governing the regenerative capacity of mammalian hearts remain incompletely understood. Exploring a comparative transcriptome analysis in regenerative neonatal vs. non-regenerative adult mouse CMs, we identified N-Cadherin, a member of Ca2+-dependent cell adhesion protein cadherin superfamily, as a potential novel regulator of CM proliferation/renewal. The primary objectives of this study were to elucidate the molecular mechanisms through which N-Cadherin regulates cardiomyocyte proliferation and regeneration, and to determine the therapeutic potential to promote CM renewal and restore cardiac function following injury by targeting N-Cadherin. Cardiac N-Cadherin expression exhibits a strong positive correlation with that of cell cycle- and proliferation-related genes. Its expression levels show an age-dependent reduction, with a 75% decrease of N-Cadherin in adult, compared to P1 neonatal, CMs. N-Cadherin expression is upregulated in the neonatal mouse heart in response to apical resection, especially in the peri-injury region, coinciding with increased CM mitotic activities in the neonatal heart. Knocking down N-Cadherin reduced, whereas overexpression of N-Cadherin increased, the proliferation activity of neonatal mouse CMs and human induced pluripotent stem cell-derived CMs. Mechanistically, increased N-Cadherin potentiates CM renewal through direct binding with and stabilization of a pro-mitotic transcription regulator β-Catenin, leading to increased CMs proliferative activity. Deletion of β-Catenin-binding domain on N-Cadherin abrogated its pro-regenerative activity. Importantly, targeted depletion of N-Cadherin in CMs resulted in incomplete cardiac repair/regeneration and excessive fibrotic scar formation in neonatal mouse hearts following injury. Cardiac-specific overexpression of N-Cadherin in adult mouse heart using adeno-associated viral vectors, by contrast, resulted in increased CM proliferation and protected against myocardial infarction-induced adverse remodeling and contractile dysfunction. Adherent junction protein N-cadherin is demonstrated to play a crucial role in maintaining CM renewal potential by post-translational stabilization of β-Catenin. Enhancing N-cadherin expression levels and downstream signaling activities in the heart, therefore, could be a powerful new approach to promote cardiac regeneration and restore myocardial function in adult human heart following injury.

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Reduced cardiac antioxidant defenses mediate increased susceptibility to workload-induced myocardial injury in males with genetic cardiomyopathy.

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