Heteroplasmy of Wild Type Mitochondrial DNA Variants in Mice Causes Metabolic Heart Disease With Pulmonary Hypertension and Frailty.
Lechuga-Vieco AV., Latorre-Pellicer A., Calvo E., Torroja C., Pellico J., Acín-Pérez R., García-Gil ML., Santos A., Bagwan N., Bonzon-Kulichenko E., Magni R., Benito M., Justo-Méndez R., Simon AK., Sánchez-Cabo F., Vázquez J., Ruíz-Cabello J., Enríquez JA.
Background: In most eukaryotic cells, the mitochondrial DNA (mtDNA) is uniparentally transmitted and present in multiple copies derived from the clonal expansion of maternally inherited mtDNA. All copies are therefore near-identical, or homoplasmic. The presence of more than one mtDNA variant in the same cytoplasm can arise naturally or result from new medical technologies aimed at preventing mitochondrial genetic diseases and improving fertility. The latter is called divergent non-pathological mtDNAs heteroplasmy (DNPH). We hypothesized that DNPH is maladaptive and usually prevented by the cell. Methods: We engineered and characterized DNPH mice throughout their lifespan using transcriptomic, metabolomic, biochemical, physiological and phenotyping techniques. We focused on in vivo imaging techniques for non-invasive assessment of cardiac and pulmonary energy metabolism. Results: We show that DNPH impairs mitochondrial function, with profound consequences in critical tissues that cannot resolve heteroplasmy, particularly cardiac and skeletal muscle. Progressive metabolic stress in these tissues leads to severe pathology in adulthood, including pulmonary hypertension and heart failure, skeletal muscle wasting, frailty, and premature death. Symptom severity is strongly modulated by the nuclear context. Conclusions: Medical interventions that may generate DNPH should address potential incompatibilities between donor and recipient mtDNA.