Altering aspects of mitochondrial quality to improve musculoskeletal outcomes in disuse atrophy---Supplementary Figure 4: Mitochondrial dynamics RNA from PGC colony

Supplementary Figure 4: mRNA content of moderators of mitochondrial fusion and fission in PGC mice. A: Mfn1 mRNA content in males. B: Mfn1 mRNA content in females. C: Mfn2 mRNA content in males. D: Mfn2 mRNA content in females. E: Opa1 mRNA content in males. F: Opa1 mRNA content in females. G: Mff mRNA content in males. H: Mff mRNA content in females. I: Drp1 mRNA content in males. J: Drp1 mRNA content in females. K: Fis1 mRNA content in males. L: Fis1 mRNA content in females. * denotes Tukey-adjusted p<0.05. Males had the following sample sizes: WT-CON= 9, WT-HU= 10, PGC-CON= 9, PGC-HU= 9. Females had the following samples sizes: WT-CON= 8, WT-HU= 9, PGC-CON= 9, PGC-HU= 9.

Article Title: Altering aspects of mitochondrial quality to improve musculoskeletal outcomes in disuse atrophy

Authors: Megan E. Rosa-Caldwell, Seongkyun Lim, Wesley S. Haynie, Lisa T. Jansen, Lauren C. Westervelt, Madeline G. Amos, Tyrone A. Washington, Nicholas P. Greene

Abstract: Muscle atrophy is a significant moderator for disease prognosis; as such, interventions to mitigate disuse-induced muscle loss are imperative to improve clinical interventions. Mitochondrial deteriorations may underlie disuse-induced myopathies; therefore, improving mitochondrial quality may be an enticing therapeutic intervention. However, different mitochondrial-based treatments may have divergent impacts on the prognosis of disuse atrophy. Therefore, the purpose of this study was to investigate different mitochondria-centered interventions during disuse atrophy in hindlimb unloaded male and female mice. Methods: Male and female mice overexpressing PGC-1α (PGC-1α) or mitochondrially-targeted catalase (MCAT) and their respective wildtype (WT) littermate controls were hindlimb unloaded for 7 days to induce disuse atrophy or allowed normal ambulatory activity (cage control; CON). After designated interventions, animals were euthanized and tissues collected for measures of mitochondrial quality control and protein turnover. Results: While PGC-1α overexpression mitigated ubiquitin-proteasome activation (MuRF1 and Atrogin mRNA content), this did not correspond to phenotypic protections from disuse-induced atrophy. Rather, PGC-1α mice appeared to have a greater reliance on autophagic protein breakdown compared to WT. In MCAT mice, females exhibited a mitigated response to disuse atrophy; however, this effect was not noted in males. Despite these phenotypic differences, there were no clear cellular signaling differences between MCAT hindlimb unloaded females and MCAT fully loaded females. Conclusion: PGC-1α overexpression does not protect against phenotypic alterations during disuse atrophy but appears to shift catabolic pathways moderating atrophy. However, increased mitochondrially-targeted catalase activity appears to blunt disuse atrophy within highly oxidative muscles specifically in female mice.