DNAJB2 expression in normal and diseased human and mouse skeletal muscle.
DNAJB2, a co-chaperone regulator of Hsp70 that is expressed principally in the nervous system, has been recently reported to be up-regulated in human skeletal muscle during its recovery from damage. Here we identified DNAJB2 expression in regenerating fibers in skeletal muscles of the dystrophic mdx mouse and patients with Duchenne muscular dystrophy. Surprisingly, in both dystrophic and control mice and patients, DNAJB2 was also expressed in non-regenerating fibers at the postsynaptic side of the neuromuscular junction. DNAJB2 functions as an adaptor molecule for the evacuation and degradation of proteins through the ubiquitin-proteasome system, and overexpression of DNAJB2 in models of the neurodegenerative disease spinobulbar muscular atrophy was shown to result in the reduction of protein inclusions. We therefore studied the possible relation of DNAJB2 expression to protein inclusion formation in skeletal muscle in biopsies of several muscle pathologies associated with protein aggregation and found in all of them a strong immunoreactivity with anti-DNAJB2 in aggregates and vacuoles. We conclude that DNAJB2 is expressed in mouse and human skeletal muscle at the neuromuscular junction of normal fibers, in the cytoplasm and membrane of regenerating fibers, and in protein aggregates and vacuoles in protein aggregate myopathies. Therefore, we propose a role for DNAJB2 in protein turnover processes in skeletal muscle.
Claeys
Kristl G
KG
Unité de Morphologie Neuromusculaire, and the Centre de Référence Neuromusculaire Paris-Est, Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, AP-HP, Paris, France
Sozanska
Magdalena
M
Martin
Jean-Jacques
JJ
Lacene
Emmanuelle
E
Vignaud
Ludivine
L
Stockholm
Daniel
D
Laforêt
Pascal
P
Eymard
Bruno
B
Kichler
Antoine
A
Scherman
Daniel
D
Voit
Thomas
T
Israeli
David
D
D000328:Adult; D000368:Aged; D000818:Animals; D002648:Child; D002675:Child, Preschool; D005260:Female; D050956:HSP40 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007223:Infant; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D008875:Middle Aged; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000473:pathology / Q000502:physiology; D020388:Muscular Dystrophy, Duchenne / Q000378:metabolism / Q000473:pathology; D009469:Neuromuscular Junction / Q000378:metabolism; D012038:Regeneration / Q000502:physiology
C121958:DNAJB2 protein, human; C552432:DNAJB2 protein, mouse; D050956:HSP40 Heat-Shock Proteins; D018832:Molecular Chaperones
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