Guttsches Ak, Brady S, et al: Proteomics of Rimmed Vacuoles Define New Risk Allele in Inclusion Body Myositis
. Annals of Neurology
. 2017 81: (feb) 227-239
Submitted by John C. Kincaid, MD, News Science Editorial Board
Sporadic inclusion body myositis (sIBM) pathogenesis in unknown rimmed vacuoles (RVs) are a constant feature. The proteins that accumulate within RVs are still incompletely known. RVs were microdissected from skeletal muscle of 18 sIBM patients and analyzed by mass spectrometry. Whole exome sequencing was performed on 62 sIBM patients. A total of 213 proteins were enriched by >1.5 -fold in RVs compared to controls and included proteins previously reported to accumulate in sIBM tissue. Proteins associated with protein folding and autophagy were the largest group represented. One autophagic adaptor protein not previously identified in sIBM was FYCO1. Rare missense coding FYCO1 variants were present in 11.3% of sIBM patients compared with 2.6% of controls (p50.003). These FYCO1 variants may impair autophagic function, leading to RV formation in sIBM patient muscle. FYCO1 functionally connects autophagic and endocytic pathways, supporting the hypothesis that impaired endolysosomal degradation underlies the pathogenesis of sIBM.
This paper is a good review of the status of the protein pathways potentially involved in the pathogenesis of sporadic IBM.
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