Zhaivoron, A. | bioRxiv Science

bioRxiv2025

NAD+ precursor treatment prevents cardiomyopathybut disrupts erythroid maturation in mitochondrial progeria

Nicotinamide adenine dinucleotide (NAD+) plays a central role in energy metabolism, and its decline is linked to various degenerative diseases. While NAD+ restoration holds therapeutic promise, its long term, tissue-specific consequences remain poorly understood. We investigated effects of nicotinamide riboside (NR) supplementation for "mutator" mice manifesting mitochondrial progeria. Our results reveal strikingly divergent outcomes: in proliferative bone marrow, NR-treated mutators show reductive stress with accumulation of NADH/NADPH, altered amino acid, nucleotide, folate levels and impaired heme biosynthesis. In blood, erythrocyte maturation defects are aggravated, exacerbating anemia. Conversely, in postmitotic cardiac tissue, NR enhanced contractility, reduces stress response markers and normalized metabolic profile. These findings indicate that while being beneficial for heart, chronic NAD+ boosting can compromise erythrocyte maturation in the context of mitochondrial disease. The data emphasize importance of evaluating systemic effects of NAD+ boosting therapies beyond the primary affected tissues and development of tissue-specific metabolic interventions for degenerative diseases. HighlightsO_LIChronic nicotinamide riboside supplementation exacerbates anemia and disrupts erythroid maturation in progeric mice. C_LIO_LIIn proliferative bone marrow cells, NR induces redox imbalance and drives profound metabolic dysregulation. C_LIO_LINR suppresses heme biosynthesis and iron transport pathways in the bone marrow. C_LIO_LIIn the heart, NR restores NAD+ levels, enhances cardiac function, and reduces metabolic stress. C_LI

physiology↗

bioRxiv2025

Nutrient-dependent pathology in mitochondrial hypertrophic cardiomyopathy model

ObjectiveMitochondrial translation defects are a major cause of early childhood hypertrophic cardiomyopathy (CMP). While the genetic basis of these disorders is being increasingly uncovered, the downstream molecular mechanisms driving disease pathogenesis remain poorly understood. In this study, we investigated the consequences of defects in mitochondrial ribosomal large subunit protein 44 (MRPL44), associated with infantile-onset CMP in human cardiomyocytes, in nutrient environments relevant to cardiac development. MethodsInduced pluripotent stem cell line with MRPL44 patient mutation and controls were differentiated to cardiomyocytes and grown in glucose or lipid-enriched medium reflecting prenatal or postnatal fuel preferences, respectively. Mitochondrial, lipid metabolic and cellular characteristics were studied by immunofluorescence and cellular transcriptome by RNA-sequencing. ResultsIn glucose-rich medium, patient-derived cardiomyocytes exhibit increased mitochondrial DNA (mtDNA) content and elevated mitochondrial transcripts. In contrast the lipid-enriched medium triggered both mitochondrial and endoplasmic reticulum -related stress responses, disrupted lipid and cholesterol homeostasis, accompanied by remodeling of the central biosynthetic pathway of one carbon metabolism. The cells accumulated lipids while also inducing lipid uptake and synthesis genes, suggesting maladaptive metabolic rewiring. ConclusionOur findings indicate that glucose and lipids, the latter being the postnatally favored cardiac fuel, exert remarkably different consequences in MRPL44 deficient cardiomyocytes. The lipid enriched medium elicited robust activation of metabolic stress responses, with chronic upregulation of anabolic biosynthesis pathways and lipid accumulation indicative of conflicting metabolic homeostasis. These observations provide a mechanistic basis for postnatal disease manifestation and highlight nutrient metabolism as a key driver in development of infantile-onset mitochondrial hypertrophic cardiomyopathy. HighlightsO_LIMRPL44 deficiency impairs mitochondrial translation but induces mtDNA replication and transcription in iPSC-derived cardiomyocytes. C_LIO_LIIn glucose conditions, MRPL44 mutant cardiomyocytes upregulate mitochondrial replication and transcription program, but not translation. C_LIO_LILipid-enriched nutrient conditions exacerbate disease phenotype, inducing mitochondrial and ER stress responses in MRPL44 deficiency. C_LIO_LIMitochondrial ribosome defect disrupts lipid homeostasis in cardiomyocytes causing impaired fatty acid oxidation, lipid accumulation and altered cholesterol metabolism. C_LI

molecular biology↗