Authors
Chihiro Hisatsune, Fumiko Shinkai-Ouchi, Shoji Hata, Yasuko Ono
Published in
The Journal of biological chemistry. Volume 302. Issue 4. Pages 111277. Epub Feb 12, 2026.
Abstract
Limb-girdle muscular dystrophy R1 (LGMDR1) is an autosomal recessive disorder caused by dysfunction of calpain-3 (CAPN3; also known as p94), a muscle-specific, Ca2+-dependent cysteine protease. LGMDR1 mutations are distributed throughout the Capn3 gene. Nevertheless, our knowledge of the biochemical and biological properties of individual LGMDR1 mutants is limited, hindering a full understanding of LGMDR1 pathogenesis. Here, we comprehensively examined the functional properties of LGMDR1 mutants within the penta-EF-hand (PEF) domain at the COOH terminus of CAPN3, focusing on their autolytic processing, oligomerization, titin binding, and subcellular localization within sarcomeres of mouse skeletal muscle. We found that oligomer formation of CAPN3 through the PEF domain contributes to efficient NH2-terminal and IS1-region processing, which were impaired by specific LGMDR1 mutations within the PEF domain. Furthermore, while WT CAPN3 predominantly localized at the sarcomeric M-bands of tibialis anterior muscles in vivo, several LGMDR1 mutants were absent from the M-bands due to decreased binding to titin, a giant cytoskeletal protein, irrespective of their oligomerization status. These findings indicate that LGMDR1 mutations within the PEF domain disrupt the physiological function of CAPN3 through both oligomer-dependent and oligomer-independent mechanisms, highlighting two distinct pathways contributing to LGMDR1 pathogenesis.
PMID:
41690592
Bibliographic data and abstract were imported from PubMed on 12 Sep 2026.
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