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Abnormal expression of RNA polymerase II ‐associated proteins in muscle of patients with myofibrillar myopathies
Author(s) -
Guglielmi Valeria,
Marini Matteo,
Masson Émilie Fiola,
Malatesta Manuela,
Forget Diane,
Tomelleri Giuliano,
Coulombe Benoit,
Vattemi Gaetano
Publication year - 2015
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.12715
Subject(s) - myofibril , immunostaining , myocyte , protein subunit , cytoplasm , staining , biology , microbiology and biotechnology , desmin , chemistry , immunohistochemistry , pathology , biochemistry , genetics , medicine , gene , immunology , vimentin
Aims Myofibrillar myopathies ( MFM s) are a group of inherited or sporadic neuromuscular disorders characterized morphologically by foci of myofibril dissolution, disintegration of the Z‐disk and insoluble protein aggregates within the muscle fibres. The sequential events leading to muscle fibre damage remains largely unknown. Methods and results We investigated the expression and the cellular localization of RNA polymerase II ( RNAPII )‐associated proteins ( RPAP s) in muscle biopsies from patients with genetically proven and sporadic MFM s. Our data demonstrated that RPAP 2, and to a lesser extent GPN 1/ RPAP 4, are accumulated focally in the cytoplasm of MFM muscle fibres in which they co‐localize with POLR 2A/ RPB 1, the largest subunit of RNAPII , and correspond to αB‐cystallin deposits in distribution and staining intensity. No abnormal staining for RPAP 2 has been observed in muscle of patients with central cores, minicores and neurogenic target fibres. Conclusions Together, these findings could provide new insights into the molecular pathogenesis of MFM s and suggest that RPAP 2 immunostaining can be a useful diagnostic tool to depict protein aggregates in MFM s.