Biology subjects

Mougenot, N.

Publications and source records attributed to Mougenot, N..

5 recordsLinked to original sources

bioRxiv2026

Maternal obesity accelerates cardiomyocyte maturation and programs adult heart dysfunction in offspring

Rationale: Maternal obesity increases cardiovascular risk in offspring, but the developmental mechanisms linking early-life metabolic stress to adult heart dysfunction remain poorly understood, and whether maternal obesity alters the postnatal maturation of the cardiomyocyte itself has not been addressed. Objective: To determine whether maternal high-fat diet alters the developmental trajectory of postnatal cardiomyocyte maturation and its functional consequences in adult offspring. Methods: In a rat model of maternal high-fat diet, longitudinal echocardiographic and invasive hemodynamic phenotyping were combined with transcriptomic, lipidomic, and ultrastructural analyses across four postnatal stages. Results: Offspring exposed to maternal high-fat diet displayed accelerated postnatal cardiac maturation, with premature activation of contractile, calcium-handling and metabolic gene programs, concentric hypertrophy, and enhanced systolic performance in juvenile life. This precocious maturation was not sustained: by adulthood, ejection fraction and intrinsic myocardial contractility progressively declined, coinciding with disorganization of sarcomeres, intercalated discs, and excitation-contraction coupling proteins, in the absence of fibrosis, lipid accumulation or major mitochondrial respiratory dysfunction. Conclusions: These findings reveal accelerated cardiomyocyte maturation as a developmental mechanism linking maternal obesity to long-term cardiac vulnerability, with cardiomyocyte cytoarchitecture disruption emerging as an early hallmark that precedes overt systolic failure. Key words: Maternal obesity, DOHaD, postnatal cardiac maturation, cardiomyocyte cytoarchitecture, systolic dysfunction

pathology↗

bioRxiv2025

The Mutated p.H222P A-type Lamins Drive Loxl2-Mediated Extracellular Matrix Remodeling in Both Patient-Derived Cardiomyocytes and Mouse Models of Dilated Cardiomyopathy

LMNA cardiomyopathy, caused by mutations in the LMNA gene, is a severe form of dilated cardiomyopathy characterized by arrhythmias, contractile dysfunction, and increased myocardial fibrosis, which impairs left ventricular function and predisposes to heart failure. While the disease has been well characterized, a lack of insight into the pathogenesis impeded the development of therapies. We here used patient-derived LMNA p.H222P cardiomyocytes (hiPSC-CMs) and their isogenic controls and a LmnaH222P/H222P mouse model to dissect abnormal cardiac mechanisms leading to the development of the disease. We showed that LMNA p.H222P hiPSC-CMs exhibit elevated diastolic calcium levels and hypocontractility. They displayed nuclear shape abnormalities, a hallmark of LMNA cardiomyopathy, associated with altered chromosome spatial organization and gene expression profiles. Using transcriptomic analysis, we further revealed that genes related to cardiac extracellular matrix (ECM) remodeling, deposition, and components are dysregulated in both LMNA p.H222P hiPSC-CMs and mutated mice, suggesting a conserved pathogenic mechanism across species. Conversely, molecular inhibition of Loxl2, a key component of the ECM establishment, preserved the cardiac function in vivo. Taken together, our findings suggest that targeting Loxl2 could be a promising therapeutic strategy to maintain cardiac function in LMNA cardiomyopathy.

pathology↗

bioRxiv2024

Gene Therapy with the N-terminal Fragment of Nav1.5 for Cardiac Channelopathies: A Novel Transcomplementation Mechanism Potentiating the Cardiac Sodium Current

BACKGROUNDCardiac channelopathies, caused by mutations in ion-channel genes, can lead to sudden cardiac death (SCD) via ventricular arrhythmias. Brugada syndrome (BrS) is a rare inherited channelopathy characterized by a unique ECG pattern and a high incidence of ventricular fibrillation leading to SCD in the absence of structural heart defects. The main gene responsible for 20-25% of BrS cases is SCN5A, encoding the cardiac sodium channel -subunit Nav1.5, which carries the sodium current (INa) responsible for the rapid depolarization phase of the action potential (AP). While current treatments do not target the genetic cause of channelopathies, this study explores the therapeutic potential of overexpressing the N-terminal region of Nav1.5 (Nter) to restore electrical activity by rescuing INa, in the context of SCN5A deficiency. METHODSWe overexpressed the Nter peptide using viral vectors in Scn5a+/- mice, in CRISPR/Cas9 edited-SCN5A+/- cardiomyocytes derived from induced-pluripotent stem cells (iPSC-CMs) and in BrS patient iPSC-CMs. We assessed molecular and functional effects of Nter overexpression in vitro and in vivo by measuring Nav1.5 subcellular expression and electrophysiological activity and by recording ECGs and arrhythmias. RESULTSWhereas Scn5a+/- mice showed an impaired INa associated with a slowed-cardiac conduction characteristic of the BrS phenotype, cardiac-specific overexpression of Nter corrected AP parameters by restoring INa density in Scn5a+/- mouse cardiomyocytes. This increase in INa density was caused by a translocation of Nav1.5 to the cell membrane in Nter-overexpressing mice. Most importantly, Nter overexpression normalized atrioventricular and ventricular conduction and protected Scn5a+/- mice from arrhythmias triggered by programmed electrical stimulation. Similarly, Nter overexpression in SCN5A+/- human iPSC-CMs led to a 2-fold increase in Nav1.5 cell-surface expression, resulting in normalization of INa and AP parameters and abolition of early after depolarizations observed during spontaneous AP recordings. Similar results were obtained in iPSC-CMs derived from a BrS patient, confirming the potential of this therapy in human models. CONCLUSIONSThis study identified a novel therapeutic peptide effective in restoring cardiac excitability in animal and cellular models of BrS, paving the way for future development of therapies for life-threatening arrhythmias in patients with SCN5A deficiency.

physiology↗

bioRxiv2024

Depleting trafficking regulator CASK promotes intercalated disc organization and ventricular function

BackgroundThe intercalated disc (ID) electromechanically couples adjacent cardiomyocytes. Alteration of this structure plays a central role in cardiac arrhythmias, notably arrhythmogenic cardiomyopathy (ACM), an inherited genetic disorder of desmosomes. Calcium/Calmodulin-Dependent Serine Protein Kinase (CASK), a costameric component of the lateral membrane, regulates cardiomyocyte protein trafficking. Here, we investigated CASK regulation of the organization of ID components in normal and pathological contexts. Here, we investigated CASK regulation of the organization of ID components in normal and pathological contexts. MethodsWe studied the outcomes of CASK depletion in neonatal rat hearts using a cardiac-specific adeno-associated virus strategy. We used conventional and strain echocardiography, hemodynamics, electrocardiography, histology, and gene and protein expression studies to characterize adult rat hearts. We also studied the effects of CASK depletion in neonatal rat ventricular cardiomyocytes (NRVM), and control and ACM (PKP2+/-) IPS cell-derived CM (hIPS-CM) using proteomics, electron microscopy, high-resolution imaging, mechano-scanning ion conductance microscopy (mechano-SICM), and stress resistance tests. We studied cardiac CASK expression and localization in human ACM and non-transplantable control hearts. ResultsDepletion of CASK in our multiple experimental models revealed that CASK regulates cardiomyocyte IDs. In rats, CASK depletion improved contractile reserve and compliance. In cultured rat cardiomyocytes, CASK knockdown increased localization of connexin 43 (Cx43) and PKP2 at IDs, resulting in increased contact stiffness. In PKP2+/- hIPS-CMs, CASK expression was increased. CASK depletion in these cells promoted PKP2 accumulation at cell contacts, formation of desmosome-like structures, and stress resistance. In the right ventricles of ACM patients, CASK protein level was also increased and CASK abnormally localized at the ID. ConclusionCASK functions as a repressor of ID organization and tissue cohesion, suggesting novel mechanisms for regulating ID structure and function. These observations, along with CASK upregulation and mislocalization in ACM, open up new perspectives on understanding the pathophysiology of ACM and suggest innovative strategies for its treatment.

physiology↗

bioRxiv2020

HIGH FAT DIET STIMULATES BETA-OXIDATION, ALTERS ELECTRICAL PROPERTIES AND INDUCES ADIPOGENICITY OF ATRIA IN OBESE MICE

Metabolic disorders such as obesity are risk factors of atrial fibrillation, not only by sharing comorbidities but likely through their direct impact on atria, notably its adipogenicity. Here, we submitted mice that lack cardiac adipose tissue to a high fat diet and first studied the atrial metabolomic and lipidomic phenotypes using liquid chromatography-mass spectrometry. We found an increased consumption of free fatty acid by the beta-oxidation and an accumulation of long-chain lipids in atria of obese mice. Free fatty acid was the main substrate of mitochondrial respiration studied in the saponin-permeabilized atrial muscle. Conducted action potential recorded in atrial trabeculae was short, and ATP-sensitive potassium current was increased in perforated patch-clamp atrial myocytes of obese mice. There was histological and phenotypical evidence for an accumulation of adipose tissue in obese mice atria. Thus, an obesogenic diet transforms the energy metabolism, causes fat accumulation and induces electrical remodeling of atria myocardium. HIGHLIGHTS- Untargeted metabolomic and lipidomic analysis revealed that a high fat diet induces profound transformation of atrial energy metabolism with beta-oxidation activation and long-chain lipid accumulation. - Mitochondria respiration studied in atrial myocardial trabecula preferentially used Palmitoyl-CoA as energy substrate in obese mice. - Atria of obese mice become vulnerable to atrial fibrillation and show short action potential due to the activation of K-ATP dependent potassium current. - Adipocytes and fat molecular markers were detected in atria of obese mice together with an inflammatory profile consistence with a myocardial accumulation of fat.

physiology↗