title: Telomere shortening and metabolic compromise underlie dystrophic cardiomyopathy.
abstract: Duchenne muscular dystrophy (DMD) is an incurable X-linked genetic disease that is caused by a mutation in the dystrophin gene and affects one in every 3,600 boys. We previously showed that long telomeres protect mice from the lethal cardiac disease seen in humans with the same genetic defect, dystrophin deficiency. By generating the mdx4cv/mTRG2mouse model with "humanized" telomere lengths, the devastating dilated cardiomyopathy phenotype seen in patients with DMD was recapitulated. Here, we analyze the degenerative sequelae that culminate in heart failure and death in this mouse model. We report progressive telomere shortening in developing mouse cardiomyocytes after postnatal week 1, a time when the cells are no longer dividing. This proliferation-independent telomere shortening is accompanied by an induction of a DNA damage response, evident by p53 activation and increased expression of its target gene p21 in isolated cardiomyocytes. The consequent repression of Pgc1α/β leads to impaired mitochondrial biogenesis, which, in conjunction with the high demands of contraction, leads to increased oxidative stress and decreased mitochondrial membrane potential. As a result, cardiomyocyte respiration and ATP output are severely compromised. Importantly, treatment with a mitochondrial-specific antioxidant before the onset of cardiac dysfunction rescues the metabolic defects. These findings provide evidence for a link between short telomere length and metabolic compromise in the etiology of dilated cardiomyopathy in DMD and identify a window of opportunity for preventive interventions.
authors: Baxter Laboratory for Stem Cell Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.|Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.|Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.|Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.
authors: Alex Chia Yu
authors: AC
authors: Chang
authors: Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.|Division of Cardiology, Department of Medicine Stanford and Department of Radiology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.
authors: Sang-Ging
authors: SG
authors: Ong
authors: Division of Radiation and Cancer Biology and Center for Clinical Sciences Research, Department of Radiation Oncology, Stanford University, Stanford, CA 94305.
authors: Edward L
authors: EL
authors: LaGory
authors: Baxter Laboratory for Stem Cell Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.|Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.|Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.
authors: Peggy E
authors: PE
authors: Kraft
authors: Division of Radiation and Cancer Biology and Center for Clinical Sciences Research, Department of Radiation Oncology, Stanford University, Stanford, CA 94305.
authors: Amato J
authors: AJ
authors: Giaccia
authors: Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.|Division of Cardiology, Department of Medicine Stanford and Department of Radiology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.
authors: Joseph C
authors: JC
authors: Wu
authors: Baxter Laboratory for Stem Cell Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305; hblau@stanford.edu.|Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.|Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.|Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford University, Stanford, CA 94305.
authors: Helen M
authors: HM
authors: Blau
mesh_terms: D000818:Animals; D002311:Cardiomyopathy, Dilated / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D002453:Cell Cycle; D049109:Cell Proliferation; D004249:DNA Damage; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008929:Mitochondria, Heart / Q000378:metabolism / Q000502:physiology; D008938:Mitosis; D009137:Muscular Dystrophy, Animal / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D020388:Muscular Dystrophy, Duchenne; D032383:Myocytes, Cardiac / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D059506:Telomere Shortening
chemical_list: D017382:Reactive Oxygen Species
keywords: Duchenne muscular dystrophy; dilated cardiomyopathy; metabolic compromise; mitochondrial dysfunction; telomere