title: Overexpression of inducible 70-kDa heat shock protein in mouse improves structural and functional recovery of skeletal muscles from atrophy.
abstract: Heat shock proteins play a key regulatory role in cellular defense. To investigate the role of the inducible 70-kDa heat shock protein (HSP70) in skeletal muscle atrophy and subsequent recovery, soleus (SOL) and extensor digitorum longus (EDL) muscles from overexpressing HSP70 transgenic mice were immobilized for 7 days and subsequently released from immobilization and evaluated after 7 days. Histological analysis showed that there was a decrease in cross-sectional area of type II myofiber from EDL and types I and II myofiber from SOL muscles at 7-day immobilization in both wild-type and HSP70 mice. At 7-day recovery, EDL and SOL myofibers from HSP70 mice, but not from wild-type mice, recovered their size. Muscle tetanic contraction decreased only in SOL muscles from wild-type mice at both 7-day immobilization and 7-day recovery; however, it was unaltered in the respective groups from HSP70 mice. Although no effect in a fatigue protocol was observed among groups, we noticed a better contractile performance of EDL muscles from overexpressing HSP70 groups as compared to their matched wild-type groups. The number of NCAM positive-satellite cells reduced after immobilization and recovery in both EDL and SOL muscles from wild-type mice, but it was unchanged in the muscles from HSP70 mice. These results suggest that HSP70 improves structural and functional recovery of skeletal muscle after disuse atrophy, and this effect might be associated with preservation of satellite cell amount.
authors.affiliation: Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, Lineu Prestes Av. 2415, São Paulo, São Paulo, 05508-000, Brazil. elenm@usp.br
authors.forename: Elen H
authors.initials: EH
authors.lastname: Miyabara
authors.forename: Tabata L
authors.initials: TL
authors.lastname: Nascimento
authors.forename: Débora C
authors.initials: DC
authors.lastname: Rodrigues
authors.forename: Anselmo S
authors.initials: AS
authors.lastname: Moriscot
authors.forename: Wilmer F
authors.initials: WF
authors.lastname: Davila
authors.forename: Younss
authors.initials: Y
authors.lastname: AitMou
authors.forename: Pieter P
authors.initials: PP
authors.lastname: deTombe
authors.forename: Ruben
authors.initials: R
authors.lastname: Mestril
mesh_terms: D000818:Animals; D002645:Chickens; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009119:Muscle Contraction / Q000502:physiology; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism* / Q000473:pathology / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism* / Q000473:pathology / Q000502:physiology; D009133:Muscular Atrophy / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D051381:Rats; D020127:Recovery of Function / Q000235:genetics / Q000502:physiology; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism / Q000473:pathology / Q000502:physiology
chemical_list: D018840:HSP70 Heat-Shock Proteins