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Full-Text Articles in Physiology
Life-Long Reduction In Myomir Expression Does Not Adversely Affect Skeletal Muscle Morphology, Ivan J. Vechetti Jr., Yuan Wen, Thomas Chaillou, Kevin A. Murach, Alexander Alimov, Vandre C. Figueiredo, Maeli Dal-Pai-Silva, John J. Mccarthy
Life-Long Reduction In Myomir Expression Does Not Adversely Affect Skeletal Muscle Morphology, Ivan J. Vechetti Jr., Yuan Wen, Thomas Chaillou, Kevin A. Murach, Alexander Alimov, Vandre C. Figueiredo, Maeli Dal-Pai-Silva, John J. Mccarthy
Physiology Faculty Publications
We generated an inducible, skeletal muscle-specific Dicer knockout mouse to deplete microRNAs in adult skeletal muscle. Following tamoxifen treatment, Dicer mRNA expression was significantly decreased by 87%. Wild-type (WT) and Dicer knockout (KO) mice were subjected to either synergist ablation or hind limb suspension for two weeks. There was no difference in muscle weight with hypertrophy or atrophy between WT and KO groups; however, even with the significant loss of Dicer expression, myomiR (miR-1, -133a and -206) expression was only reduced by 38% on average. We next aged WT and KO mice for ~22 months following Dicer inactivation to determine …
Human Skeletal Muscle Macrophages Increase Following Cycle Training And Are Associated With Adaptations That May Facilitate Growth, R. Grace Walton, Kate Kosmac, Jyothi Mula, Christopher S. Fry, Bailey D. Peck, Jason S. Groshong, Brian S. Finlin, Beibei Zhu, Philip A. Kern, Charlotte A. Peterson
Human Skeletal Muscle Macrophages Increase Following Cycle Training And Are Associated With Adaptations That May Facilitate Growth, R. Grace Walton, Kate Kosmac, Jyothi Mula, Christopher S. Fry, Bailey D. Peck, Jason S. Groshong, Brian S. Finlin, Beibei Zhu, Philip A. Kern, Charlotte A. Peterson
Center for Muscle Biology Faculty Publications
Skeletal muscle macrophages participate in repair and regeneration following injury. However, their role in physiological adaptations to exercise is unexplored. We determined whether endurance exercise training (EET) alters macrophage content and characteristics in response to resistance exercise (RE), and whether macrophages are associated with other exercise adaptations. Subjects provided vastus lateralis biopsies before and after one bout of RE, after 12 weeks of EET (cycling), and after a final bout of RE. M2 macrophages (CD11b+/CD206+) did not increase with RE, but increased in response to EET (P < 0.01). Increases in M2 macrophages were positively correlated with fiber hypertrophy (r = 0.49) and satellite cells (r = 0.47). M2c macrophages (CD206+/CD163+) also increased following EET (P < 0.001), and were associated with fiber hypertrophy (r = 0.64). Gene expression was quantified using NanoString. Following EET, the change in M2 macrophages was positively associated with changes in HGF, IGF1, and extracellular matrix genes. EET decreased expression of IL6 (P < 0.05), C/EBPβ (P < 0.01), and MuRF (P < 0.05), and increased expression of IL-4 (P < 0.01), TNFα (P < 0.01) and the TWEAK receptor FN14 (P < 0.05). The change in FN14 gene expression was inversely associated with changes in C/EBPβ (r = −0.58) and MuRF (r = −0.46) following EET. In cultured human myotubes, siRNA inhibition of FN14 increased expression of C/EBPβ (P < 0.05) and MuRF (P < 0.05). Our data suggest that macrophages contribute to the muscle response to EET, potentially including modulation of TWEAK-FN14 signaling.