Proteomics of rimmed vacuoles define new risk allele in inclusion body myositis
Proteomics of rimmed vacuoles define new risk allele in inclusion body myositis
复制标题
DOI：
10.1002/ana.24847
复制
发表时间：
2017-02-01
影响因子：
11.2
通讯作者：
Kley, Rudolf A.
中科院分区：
文献类型：
--
作者：
Guettsches, Anne-Katrin;Brady, Stefen;Kley, Rudolf A.
目的散发性包涵体肌炎（sIBM）发病机制尚不清楚；然而，边缘液泡（RVs）是一个恒定的特征。我们建议鉴定在rv中积累的蛋白质。方法对18例sIBM患者骨骼肌的srv和完整肌纤维进行激光显微解剖，并采用基于无标记光谱计数的相对蛋白定量的灵敏质谱方法进行分析。对62例sIBM患者进行了全外显子组测序。对患者和小鼠骨骼肌进行免疫荧光检测。结果与对照组相比，共有213种蛋白质在RVs中富集，其中包括先前报道的在sIBM组织中积累或突变时引起RVs肌病的蛋白质。与蛋白质折叠和自噬相关的蛋白质是最大的一类。一个先前未在sIBM中发现的自噬接头蛋白是FYCO1。11.3%的sIBM患者存在罕见的错义编码FYCO1变异，而对照组为2.6% （p=0.003）。在sIBM和其他RV肌病中，FYCO1与自噬蛋白如MAP1LC3和SQSTM1共定位于RV。一种FYCO1变异蛋白在小鼠肌肉中表达时减少了与MAP1LC3的共定位。本研究使用无偏倚的蛋白质组学方法鉴定了sIBM中的RV蛋白，其中包括一种参与sIBM发病机制的新蛋白。FYCO1在RVs中积累，并且FYCO1的罕见错义变体在sIBM患者中被过度代表。这些FYCO1变异可能损害自噬功能，导致sIBM患者肌肉中的RV形成。FYCO1在功能上连接自噬和内吞途径，支持了内溶酶体降解受损是sIBM发病机制的假设。神经网络学报2017；81:227 - 239
ObjectiveSporadic inclusion body myositis (sIBM) pathogenesis is unknown; however, rimmed vacuoles (RVs) are a constant feature. We propose to identify proteins that accumulate within RVs.MethodsRVs and intact myofibers were laser microdissected from skeletal muscle of 18 sIBM patients and analyzed by a sensitive mass spectrometry approach using label-free spectral count-based relative protein quantification. Whole exome sequencing was performed on 62 sIBM patients. Immunofluorescence was performed on patient and mouse skeletal muscle.ResultsA total of 213 proteins were enriched by >1.5-foldin RVs compared to controls and included proteins previously reported to accumulate in sIBM tissue or when mutated cause myopathies with RVs. 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 (p=0.003). FYCO1 colocalized at RVs with autophagic proteins such as MAP1LC3 and SQSTM1 in sIBM and other RV myopathies. One FYCO1 variant protein had reduced colocalization with MAP1LC3 when expressed in mouse muscle.InterpretationThis study used an unbiased proteomic approach to identify RV proteins in sIBM that included a novel protein involved in sIBM pathogenesis. FYCO1 accumulates at RVs, and rare missense variants in FYCO1 are overrepresented in sIBM patients. 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. Ann Neurol 2017;81:227-239