Medical College of Wisconsin
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Continuous contractile activity induces fiber type specific expression of HSP70 in skeletal muscle. Am J Physiol 1996 Dec;271(6 Pt 1):C1828-37

Date

12/01/1996

Pubmed ID

8997182

DOI

10.1152/ajpcell.1996.271.6.C1828

Scopus ID

2-s2.0-0030465870   77 Citations

Abstract

Continuous contractile activity of skeletal muscle elicits an early and dramatic increase in ribosomal RNA, suggesting that translational efficiency and/or capacity is enhanced during the adaptive response to increased metabolic demand. In view of the important role heat shock or stress proteins (HSPs) play as molecular chaperones during protein synthesis, we examined whether expression of the inducible 70-kDa HSP (HSP70) and/or mitochondrial 60-kDa HSP (HSP60) is altered in rabbit tibialis anterior muscle during continuous low-frequency motor nerve stimulation. Induction of the HSP70 gene was evident within 24 h after the onset of stimulation as reflected by increases in HSP70 transcription (> 20-fold) and mRNA (> 50-fold). HSP70 protein levels were significantly elevated (10- to 12-fold) after 14 and 21 days of stimulation. Mitochondrial HSP60 mRNA and protein also increased during stimulation (> 18- and > 5-fold after 21 days, respectively). In situ hybridization and immunohistochemistry coupled with myosin ATPase staining revealed that expression of HSP70 was restricted to oxidative type I and IIa fibers during the first 3 days of stimulation but shifted to primarily type II fibers after 21 days of stimulation. These findings demonstrate that induction of HSP70 during the adaptive response to chronic motor nerve stimulation proceeds from type I/IIa to type IId(x)/b fibers, suggesting that the expression of HSPs may be required to support the folding and compartmentalization of nascent proteins during the transformation process.

Author List

Neufer PD, Ordway GA, Hand GA, Shelton JM, Richardson JA, Benjamin IJ, Williams RS

Author

Ivor J. Benjamin MD Center Director, Professor in the Medicine department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Gene Expression Regulation
HSP70 Heat-Shock Proteins
In Situ Hybridization
Muscle Contraction
Muscle Fibers, Skeletal
Muscle, Skeletal
RNA, Messenger
Rabbits
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a