IMR Press / FBS / Volume 14 / Issue 3 / DOI: 10.31083/j.fbs1403019
Open Access Original Research
Inducible Heat Shock Protein 70 Levels in Patients and the mdx Mouse Affirm Regulation during Skeletal Muscle Regeneration in Muscular Dystrophy
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1 Laboratory for Neuropathology, Department of Neurology, Ghent University, 9000 Ghent, Belgium
2 Ghent-Fertility and Stem cell Team (G-FaST), Department of Human Structure and Repair, Ghent University, 9000 Ghent, Belgium
3 Neuromuscular Reference Center, Ghent University Hospital, 9000 Ghent, Belgium
*Correspondence: (Boel De Paepe)
Academic Editor: Gustavo Caetano-Anollés
Front. Biosci. (Schol Ed) 2022, 14(3), 19;
Submitted: 15 March 2022 | Revised: 16 May 2022 | Accepted: 26 May 2022 | Published: 15 July 2022
Copyright: © 2022 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license.

Background: Stress-inducible heat shock protein 70 (HSP70) is both a protective chaperone involved in protein homeostasis and an immune regulator. In both capacities, HSP70 has been implicated in muscle disorders, yet with fragmented and differing results. In this study we aimed to compare results obtained in the mouse model for the severest form of muscular dystrophy (MD) equivalent to Duchenne MD, termed the mdx mouse, with results obtained in human MD. Methods: Skeletal muscle and serum samples were obtained from 11 healthy controls, 11 fully characterized patients diagnosed with Becker MD and limb girdle MD (LGMD), and six muscle disease controls. In addition, muscle extracts were prepared from tibialis anterior of mdx and control mice at ages 4, 8 and 12 weeks. The HSP70 levels were quantified using RT-PCR, western blotting and protein arrays, and localized in muscle tissue sections using double immunofluorescence. Results: We found selective and significant 2.2-fold upregulation of HSP70 protein in mdx tibialis muscle at the earliest disease phase only. In LGMD and Becker MD patients, HSP70 protein levels were not significantly different from those of healthy muscle and serum. HSP70 was localized to regenerating muscle fibers both in mouse and human MD skeletal muscle tissues. Toll-like receptor (TLR) 2 and TLR4 expression was moderately increased on the sarcolemma in MD muscle, yet protein levels were not significantly different from normal controls. Conclusions: HSP70 upregulation in MD appears disease stage-dependent, marking the phase of most active muscle regeneration in the mdx mouse. We postulate that well-timed supportive therapeutic interventions with HSP70 agonists could potentially improve muscle tissue’s regenerative capacities in MD, attenuating loss of muscle mass while we await gene therapies to become more widely available.

Becker muscular dystrophy
Duchenne muscular dystrophy
heat shock protein 70
limb girdle muscular dystrophy
muscle regeneration
Fig. 1.
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