Effective Fiber Hypertrophy in Satellite Cell-depleted Skeletal Muscle

Authors

John J. McCarthy, University of KentuckyFollow
Jyothi Mula, University of KentuckyFollow
Mitsunori Miyazaki, University of Kentucky
Rod Erfani, University of Kentucky
Kelcye Garrison, University of Kentucky
Amreen B. Farooqui, University of Kentucky
Ratchakrit Srikuea, University of KentuckyFollow
Benjamin A. Lawson, University of Kentucky
Barry Grimes, University of Kentucky
Charles Keller, Oregon Health and Science University
Gary Van Zant, University of Kentucky
Kenneth S. Campbell, University of KentuckyFollow
Karyn A. Esser, University of KentuckyFollow
Esther E. Dupont-Versteegden, University of KentuckyFollow
Charlotte A. Peterson, University of KentuckyFollow

Abstract

An important unresolved question in skeletal muscle plasticity is whether satellite cells are necessary for muscle fiber hypertrophy. To address this issue, a novel mouse strain (Pax7-DTA) was created which enabled the conditional ablation of >90% of satellite cells in mature skeletal muscle following tamoxifen administration. To test the hypothesis that satellite cells are necessary for skeletal muscle hypertrophy, the plantaris muscle of adult Pax7-DTA mice was subjected to mechanical overload by surgical removal of the synergist muscle. Following two weeks of overload, satellite cell-depleted muscle showed the same increases in muscle mass (approximately twofold) and fiber cross-sectional area with hypertrophy as observed in the vehicle-treated group. The typical increase in myonuclei with hypertrophy was absent in satellite cell-depleted fibers, resulting in expansion of the myonuclear domain. Consistent with lack of nuclear addition to enlarged fibers, long-term BrdU labeling showed a significant reduction in the number of BrdU-positive myonuclei in satellite cell-depleted muscle compared with vehicle-treated muscle. Single fiber functional analyses showed no difference in specific force, Ca(2+) sensitivity, rate of cross-bridge cycling and cooperativity between hypertrophied fibers from vehicle and tamoxifen-treated groups. Although a small component of the hypertrophic response, both fiber hyperplasia and regeneration were significantly blunted following satellite cell depletion, indicating a distinct requirement for satellite cells during these processes. These results provide convincing evidence that skeletal muscle fibers are capable of mounting a robust hypertrophic response to mechanical overload that is not dependent on satellite cells.

Document Type

Article

Publication Date

9-1-2011

Notes/Citation Information

Published in Development, v. 138, no. 17, p. 3657-3666.

Digital Object Identifier (DOI)

http://dx.doi.org/10.1242/dev.068858

Repository Citation

McCarthy, John J.; Mula, Jyothi; Miyazaki, Mitsunori; Erfani, Rod; Garrison, Kelcye; Farooqui, Amreen B.; Srikuea, Ratchakrit; Lawson, Benjamin A.; Grimes, Barry; Keller, Charles; Van Zant, Gary; Campbell, Kenneth S.; Esser, Karyn A.; Dupont-Versteegden, Esther E.; and Peterson, Charlotte A., "Effective Fiber Hypertrophy in Satellite Cell-depleted Skeletal Muscle" (2011). Physical Therapy Faculty Publications. 20.
https://uknowledge.uky.edu/rehabsci_facpub/20