IBMPFD MUTATIONS IMPAIR UPS FUNCTION

包涵体肌病(IBM)是使骨骼肌功能障碍的疾病，并被认为 一种典型的与年龄相关的肌肉疾病。目前还没有有效的治疗方法。IBM的肌肉有 特征性的“有边框的空泡”和嗜酸性的包涵体。这些结构包含 泛素化和未降解的不溶性蛋白，包括ss-淀粉样蛋白和磷酸化tau； 阿尔茨海默病患者大脑中积累的蛋白质。这种重叠的病理表明 IBM与神经退行性疾病的共同致病机制。此链接是 P97/VCP蛋白突变的鉴定进一步加强了这一点 常染色体显性遗传综合征，IBMPFD，IBM与Paget病相关，以及 额颞性痴呆(FTD)。P97/VCP是胞浆来源的降解所必需的 蛋白酶体底物以及与内质网相关的降解 错误折叠的分泌型或跨膜蛋白。它通过选择性地与 通过辅因子泛素化底物，并将它们转移到26S蛋白酶体机械。 目前还不清楚p97/VCP突变是如何导致疾病的。IBMPFD脑和 肌肉中含有泛素化的蛋白质包涵体。我们的研究表明IBMPFD突变体 P97/VCP导致细胞内泛素化蛋白的增加。骨骼肌的表达 IBMPFD突变体p97/VCP在小鼠体内导致泛素化蛋白增加 6个月后出现虚弱和肌病改变前的生命天数。我们 建议(1)研究IBMPFD突变体p97/VCP的生化特性 结构、酶活性和底物结合。我们还将(2)评估以下措施的效果 IBMPFD突变体p97/VCP对细胞培养中泛素-蛋白酶体系统(UPS)的影响 转基因动物。这些研究将在体内使用UPS功能的生物发光成像 活体动物的骨骼肌。最后(3)我们将把上面得到的结果与 两个互补缺失的p97/VCP功能模型。虽然这是一种罕见的疾病，但对 IBMPFD对于了解UPS在正常衰老和与衰老相关的过程中的作用至关重要 如sIBM和FTD等疾病。

Inclusion body myopathies (IBM) are disabling skeletal muscle disorders and considered a prototypical age related muscle disease. There is no effective treatment. IBM muscle has characteristic "rimmed vacuoles" and eosinophilic inclusions. These structures contain ubiquitinated and undegraded insoluble proteins that include ss-amyloid and phosphorylated tau; proteins that accumulate in Alzheimer's Disease brains. This overlapping pathology suggests a common pathogenic mechanism between IBM and neurodegenerative disorders. This link is strengthened further by the identification of mutations in the protein p97/VCP that cause the autosomal dominant syndrome, IBMPFD, IBM associated with paget's disease of the bone and frontotemporal dementia (FTD). p97/VCP is essential for the degradation of cytosolic derived proteasome substrates as well as for endoplasmic reticulum associated degradation of misfolded secreted or transmembrane proteins. It performs this role by selectively binding with ubiquitinated substrates via co-factors and transferring them to the 26S proteasome machinery. Currently it is unclear how mutations in p97/VCP cause disease. IBMPFD brain and muscle contains ubiquitinated protein inclusions. Our studies demonstrate that IBMPFD mutant p97/VCP leads to an increase in ubiquitinated proteins in cells. Skeletal muscle expression of IBMPFD mutant p97/VCP in mice causes an increase in ubiquitinated proteins as early as 30 days of life before weakness and myopathic changes which occur after 6 months of age. We propose to (1) study the biochemical properties of IBMPFD mutant p97/VCP with regard to structure, enzymatic activity and substrate binding. We will also (2) evaluate the effect of IBMPFD mutant p97/VCP on the ubiquitin-proteasome system (UPS) in cell culture and transgenic animals. These studies will use in vivo bioluminescent imaging of UPS function in skeletal muscle from living animals. Finally (3) we will compare the results obtained above with two complementary loss of p97/VCP function models. Although a rare disorder, the study of IBMPFD is essential to understand the role of the UPS in normal aging and aging related disorders such as sIBM and FTD.