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Regulation of the autophagy system during chronic contractile activity-induced muscle adaptations.
Physiol Rep 2017; 5(14)PR

Abstract

Skeletal muscle is adaptable to exercise stimuli via the upregulation of mitochondrial biogenesis, and recent studies have suggested that autophagy also plays a role in exercise-induced muscle adaptations. However, it is still obscure how muscle regulates autophagy over the time course of training adaptations. This study examined the expression of autophagic proteins in skeletal muscle of rats exposed to chronic contractile activity (CCA; 6 h/day, 9V, 10 Hz continuous, 0.1 msec pulse duration) for 1, 3, and 7 days (n = 8/group). CCA-induced mitochondrial adaptations were observed by day 7, as shown by the increase in mitochondrial proteins (PGC-1α, COX I, and COX IV), as well as COX activity. Notably, the ratio of LC3 II/LC3 I, an indicator of autophagy, decreased by day 7 largely due to a significant increase in LC3 I. The autophagic induction marker p62 was elevated on day 3 and returned to basal levels by day 7, suggesting a time-dependent increase in autophagic flux. The lysosomal system was upregulated early, prior to changes in mitochondrial proteins, as represented by increases in lysosomal system markers LAMP1, LAMP2A, and MCOLN1 as early as by day 1, as well as TFEB, a primary regulator of lysosomal biogenesis and autophagy flux. Our findings suggest that, in response to chronic exercise, autophagy is upregulated concomitant with mitochondrial adaptations. Notably, our data reveal the surprising adaptive plasticity of the lysosome in response to chronic contractile activity which enhances muscle health by providing cells with a greater capacity for macromolecular and organelle turnover.

Authors+Show Affiliations

Muscle Health Research Centre, School of Kinesiology and Health Science York University, Toronto, Ontario, Canada. School of Kinesiology and Health Science York University, Toronto, Ontario, Canada.Muscle Health Research Centre, School of Kinesiology and Health Science York University, Toronto, Ontario, Canada dhood@yorku.ca. School of Kinesiology and Health Science York University, Toronto, Ontario, Canada.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28720712

Citation

Kim, Yuho, and David A. Hood. "Regulation of the Autophagy System During Chronic Contractile Activity-induced Muscle Adaptations." Physiological Reports, vol. 5, no. 14, 2017.
Kim Y, Hood DA. Regulation of the autophagy system during chronic contractile activity-induced muscle adaptations. Physiol Rep. 2017;5(14).
Kim, Y., & Hood, D. A. (2017). Regulation of the autophagy system during chronic contractile activity-induced muscle adaptations. Physiological Reports, 5(14), doi:10.14814/phy2.13307.
Kim Y, Hood DA. Regulation of the Autophagy System During Chronic Contractile Activity-induced Muscle Adaptations. Physiol Rep. 2017;5(14) PubMed PMID: 28720712.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Regulation of the autophagy system during chronic contractile activity-induced muscle adaptations. AU - Kim,Yuho, AU - Hood,David A, PY - 2017/04/13/received PY - 2017/05/10/revised PY - 2017/05/10/accepted PY - 2017/7/20/entrez PY - 2017/7/20/pubmed PY - 2018/4/24/medline KW - Autophagy KW - exercise KW - lysosome KW - mitochondrial biogenesis JF - Physiological reports JO - Physiol Rep VL - 5 IS - 14 N2 - Skeletal muscle is adaptable to exercise stimuli via the upregulation of mitochondrial biogenesis, and recent studies have suggested that autophagy also plays a role in exercise-induced muscle adaptations. However, it is still obscure how muscle regulates autophagy over the time course of training adaptations. This study examined the expression of autophagic proteins in skeletal muscle of rats exposed to chronic contractile activity (CCA; 6 h/day, 9V, 10 Hz continuous, 0.1 msec pulse duration) for 1, 3, and 7 days (n = 8/group). CCA-induced mitochondrial adaptations were observed by day 7, as shown by the increase in mitochondrial proteins (PGC-1α, COX I, and COX IV), as well as COX activity. Notably, the ratio of LC3 II/LC3 I, an indicator of autophagy, decreased by day 7 largely due to a significant increase in LC3 I. The autophagic induction marker p62 was elevated on day 3 and returned to basal levels by day 7, suggesting a time-dependent increase in autophagic flux. The lysosomal system was upregulated early, prior to changes in mitochondrial proteins, as represented by increases in lysosomal system markers LAMP1, LAMP2A, and MCOLN1 as early as by day 1, as well as TFEB, a primary regulator of lysosomal biogenesis and autophagy flux. Our findings suggest that, in response to chronic exercise, autophagy is upregulated concomitant with mitochondrial adaptations. Notably, our data reveal the surprising adaptive plasticity of the lysosome in response to chronic contractile activity which enhances muscle health by providing cells with a greater capacity for macromolecular and organelle turnover. SN - 2051-817X UR - https://www.unboundmedicine.com/medline/citation/28720712/Regulation_of_the_autophagy_system_during_chronic_contractile_activity_induced_muscle_adaptations_ L2 - https://doi.org/10.14814/phy2.13307 DB - PRIME DP - Unbound Medicine ER -