Potential mitochondrial dysfunction in skeletal muscle of mouse models of Osteogenesis imperfecta.

Abstract

Osteogenesis imperfecta (OI), also referred to as brittle bone disease, is a heritable connective tissue disorder characterized by short stature, fragile bones, craniofacial deformity and muscle weakness. OI is most often the result of autosomal dominant gene defects in the type I collagen genes: COL1A1 and COL1A2. The remaining rare autosomal recessive forms result from defects in gene products responsible for modification and packaging of type I collagen. Muscle weakness not only impacts a patient's quality of life, but likely negatively affects bone health via altered bone‐muscle crosstalk.The oim/oim mouse models severe human type III OI with reduced body mass, skeletal fragility, and reduced muscle mass and function compared to their wildtype (WT) counterparts. Whereas, the G610C OI mouse models the less severe human type I/IV OI with skeletal weakness, but near normal muscle function. The differential presence of inherent muscle pathology between oim/oim and G610C mice suggest mutation specific mechanisms.To investigate the mechanisms underlying the muscle pathology, we examined citrate synthase activity, a known marker of mitochondrial activity and determined, in the mixed fiber type gastrocnemius muscle, that citrate synthase activity was significantly increased only in oim/oim mice relative to WT mice, despite evidence of reduced muscle function; whereas G610C mice did not have altered citrate synthase activity. The unexpected increase in citrate synthase activity led to the question of whether or not mitochondria play a role in the muscle weakness observed in OI. To assess mitochondrial health, we examined biomarkers of mitogenesis and mitophagy, and found increased mitogenesis in oim/oim mice relative to WT as determined by PGC1α and TFAM protein content in the mixed gastrocnemius muscle. Additionally, measurement of mitochondrial electron transport complex proteins also suggest altered mitochondria in the oim/oim mice. These data suggest that oim/oim mice have increased mitogenesis and altered mitochondrial function accompanying decreased muscle function.Support or Funding InformationSupported by March of Dimes, National Institutes of Health/National Institute of Arthritis and Musculoskeletal and Skin Diseases (RO1 AR055907), the Leda J. Sears Trust, the Kansas City Area Life Sciences Institute Patton Trust Research, Inc., University of Missouri Research Board Grant, and in part by the Department of Veterans Affairs (VA‐Merit Grant I01BX003271‐01). A portion of this work was also supported by resources and the use of facilities at the Harry S. Truman Memorial Veterans Hospital in Columbia, MO.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.