%0 Journal Article
%T Abnormal expression of RNA polymerase II-associated proteins in muscle of patients with myofibrillar myopathies.
%A Guglielmi V
%A Marini M
%A Masson ÉF
%A Malatesta M
%A Forget D
%A Tomelleri G
%A Coulombe B
%A Vattemi G
%J Histopathology
%V 67
%N 6
%D Dec 2015
%M 25891782
%F 7.778
%R 10.1111/his.12715
%X <B>OBJECTIVE: </B>Myofibrillar myopathies (MFMs) 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.<BR><B>RESULTS: </B>We investigated the expression and the cellular localization of RNA polymerase II (RNAPII)-associated proteins (RPAPs) in muscle biopsies from patients with genetically proven and sporadic MFMs. Our data demonstrated that RPAP2, and to a lesser extent GPN1/RPAP4, are accumulated focally in the cytoplasm of MFM muscle fibres in which they co-localize with POLR2A/RPB1, the largest subunit of RNAPII, and correspond to αB-cystallin deposits in distribution and staining intensity. No abnormal staining for RPAP2 has been observed in muscle of patients with central cores, minicores and neurogenic target fibres.<BR><B>CONCLUSIONS: </B>Together, these findings could provide new insights into the molecular pathogenesis of MFMs and suggest that RPAP2 immunostaining can be a useful diagnostic tool to depict protein aggregates in MFMs.