Toxicity of a SUMOylated Fragment of the Glial Glutamate Transporter EAAT2 in ALS

描述（由申请人提供）：在美国任何时候都有30，000例ALS病例。目前，ALS没有治愈方法，治疗选择很少。90%的病例病因不明，但10%有明确的遗传来源。研究遗传病例使人们对这种疾病有了更深入的了解，这种疾病适用于散发性和家族性病例。基于ALS连锁基因突变的动物模型和散发性ALS的体外模型的持续工作将继续增加对该疾病的了解。 尽管ALS的特征是上下运动神经元变性，但也伴随着胶质细胞功能障碍。特别是，神经胶质谷氨酸转运蛋白EAAT 2的蛋白质水平在ALS患者和动物模型中降低。EAAT 2被半胱天冬酶3切割，产生截短形式的EAAT 2和C末端片段（CTE）。SUMO化形式的CTE（CTE-SUMO 1）在ALS的SOD 1-G93 A小鼠模型的脊髓内积累。 必须在体外和体内分析CTE-SUMO 1产生的机制，以便潜在地发现毒性机制。有两种不同的途径必须被共激活以产生CTE-SUMO 1;导致EAAT 2切割的半胱天冬酶-3的激活和EAAT 2/CTE的SUMO化。拟议的研究将检查ALS的参数内的两个反应的动力学。 此外，检查星形胶质细胞内CTE-SUMO 1表达可能对邻近运动神经元产生的毒性作用，将揭示ALS发病机制的另一个可能领域。先前在共培养模型中的工作表明，星形胶质细胞核内的CTE-SUMO 1积累对邻近的运动神经元是有毒的。这个问题将在体内使用一种新的转基因小鼠模型进一步研究。

DESCRIPTION (provided by applicant): There are 30,000 cases of ALS at any given time in the United States. Presently there is no cure for ALS and few treatment options. 90 percent of cases have unknown etiology, but 10 percent have a clear genetic origin. Studying the genetic cases has allowed great insight into the disease, which is applicable to both sporadic and familial cases. Continued work with animal models based on ALS-linked gene mutations and in vitro models of sporadic ALS will continue to increase knowledge of the disorder. Although ALS is characterized by the degeneration of upper and lower motor neurons there is concomitant dysfunction of glial cells. In particular, protein levels of the glial glutamate transporter EAAT2 decreases in patients and animal models of ALS. EAAT2 is cleaved by caspase 3 creating a truncated form of EAAT2 and a C-terminal fragment (CTE). A SUMOylated version of CTE (CTE-SUMO1) accumulates within the spinal cord of the SOD1-G93A mouse model of ALS. The mechanisms of CTE-SUMO1 creation must be analyzed in vitro and in vivo in order to potentially discover the mechanisms of toxicity. There are two distinct pathways that must be co-activated to create CTE- SUMO1; activation of capase-3 leading to EAAT2 cleavage and the SUMOylation of EAAT2/CTE. The proposed studies will examine the dynamics of both reactions within the parameters of ALS. In addition examination of the possible toxic effects that CTE-SUMO1 expression within astrocytes may have on neighboring motor neurons will expose another possible area of ALS pathogenesis. Previous work in a co-culture model has indicated that CTE-SUMO1 accumulation within astrocyte nuclei is toxic to neighboring motor neurons. This question will be further examined in vivo using a novel transgenic mouse model.