What is the molecular mechanism underlying cardiomyopathy in Duchenne muscular dystrophy?5 answersThe molecular mechanisms contributing to cardiomyopathy in Duchenne muscular dystrophy (DMD) involve various factors. The absence of dystrophin leads to disruption of the dystrophin-associated protein complex (DAPC), affecting proteins like neuronal nitric oxide synthase (nNOS). This disruption can result in calcium mishandling and overload in cardiac myocytes, leading to muscle cell death and diminished contractile function. Additionally, DMD cardiomyocytes (DMD-CMs) exhibit altered ion channel expression, including potassium and calcium handling proteins, contributing to calcium transient abnormalities and hypocontractility. Furthermore, DMD-iCMs secrete exosomes containing altered microRNA profiles, such as upregulation of miR-339-5p, which modulates stress-responsive genes and impairs cellular stress response, potentially exacerbating cardiomyopathy in DMD. These findings collectively highlight the multifaceted molecular mechanisms involved in the development of cardiomyopathy in DMD.
Does the presence of TFG mutations impact on mitochondrial physiology?4 answersMutations in the TFG gene have been shown to impact mitochondrial physiology. Studies have demonstrated that mutant TFG proteins lead to mitochondrial fragmentation, which correlates with the severity of clinical symptoms. Additionally, fibroblasts from patients with TFG mutations exhibit altered mitochondrial network and inner membrane potential, as well as metabolic impairment. Furthermore, TIMM50 deficiency, caused by mutations in the TFG gene, results in severe mitochondrial dysfunction, including aberrant mitochondrial cristae organization, reduced assembly of oxidative phosphorylation complexes, and decreased respiratory capacity. These findings suggest that TFG mutations can disrupt mitochondrial function, potentially contributing to the pathogenesis of various neurodegenerative conditions.
Dopeople with mitochondrial dysfunction cause accelerated ageing5 answersMitochondrial dysfunction is closely linked to accelerated aging. Dysfunctional mitochondria in T cells have been shown to induce multimorbidity and premature senescence. In MDPL Syndrome, a genetic premature aging disease, mitochondrial dysfunction is a hallmark, leading to impaired mitochondrial biogenesis and activity. Mitochondrial dysfunction, characterized by decreased respiratory capacity, membrane potential, and increased production of reactive oxygen species (ROS), is both a cause and consequence of cellular senescence. Age-related mitochondrial dysfunction also contributes to the development of type 2 diabetes mellitus (T2D) by impairing ATP production and glucose oxidation. Mitochondrial uncoupling proteins (UCPs) play a protective role against age-related oxidative stress in T2D. Severe mitochondrial dysfunction can lead to a range of diseases and accelerate the aging process.
Which genetic mutations lead to the development of cardiomyopathy?4 answersMutations in the Phospholamban gene, specifically the absence of Arginine at position 14 (PLN-R14Del), are causing severe cardiomyopathy leading to cardiac transplantation in the Netherlands. Approximately 25% of transplanted patients carry this mutation. Mutations in sarcomeric genes, such as MYBPC3, are also associated with hypertrophic cardiomyopathy (HCM). Tropomyosin (Tpm) mutations, including M8R, K15N, A277V, M281T, and I284V, have been found to cause inherited cardiac diseases like hypertrophic and dilated cardiomyopathies. Mutations in the PRKAG2 gene have been linked to hypertrophic cardiomyopathy, with early childhood onset and rapid progression.
What deficiencies do people with cardiomyopathy have?5 answersPeople with cardiomyopathy can have deficiencies in vitamin D, selenium, calcium, and magnesium. Additionally, mitochondrial disorders can also lead to cardiomyopathy, with deficiencies in thymidine kinase 2and alanyl-tRNA synthetase 2being associated with the condition. In some cases, excessive excretion of 3-methylglutaconic acid has been found, indicating underlying respiratory-chain defects.
Mitochondrial calcium in the failing heart– too much, or not enough?4 answersMitochondrial calcium balance in the failing heart remains a topic of debate. Some studies suggest that there is excessive mitochondrial calcium signaling in heart failure, leading to oxidative stress, impaired bioenergetics, and the opening of the mitochondrial permeability transition pore. On the other hand, other studies propose that mitochondrial calcium signaling is depressed in heart failure, resulting in reduced ATP production and increased release of reactive oxygen species. The regulation and functional impact of mitochondrial calcium in heart failure are still not fully understood, and further research is needed to determine the optimal approach to therapeutic intervention.