Galgt2, dystroglycan, and muscle extracellular matrix

这个项目的广泛目标是确定糖基化在神经肌肉发育和疾病中的功能作用。这项工作将集中在糖基转移酶Galgt2的作用上，它产生细胞毒性T细胞(CT)碳水化合物抗原。在哺乳动物骨骼肌中，Galgt2和CT抗原通常都局限于神经肌肉接头。CT抗原在肌纤维膜突触外区域的异位表达改变了其他正常突触蛋白的表达，包括突触层粘连蛋白、中性粒细胞营养素和神经细胞黏附分子(NCAM)。此外，Galgt2的过度表达改变了肌肉和神经肌肉发育的重要方面，以及 抑制Duchenne肌营养不良症模型MDX小鼠肌肉营养不良的形成。在转基因肌肉中，被Galgt2糖基化的主要蛋白质是α-肌营养不良聚糖，它是细胞外基质(ECM)的主要结合蛋白。这项资助将测试一种模型，在该模型中，Galgt2对营养不良多糖的修饰会改变其性质和功能。此外，它还将使用肌肉细胞、转基因小鼠和基因敲除小鼠来测试层粘连蛋白表达变化的机制。这些实验将破译Galgt2在肌肉和神经肌肉发育中的功能作用以及它的机制。 肌营养不良症的治疗作用。

The broad objective of this project is to define the functional roles for glycosylation in neuromuscular development and disease. This work will focus on the roles of a glycosyltransferase, Galgt2, which creates the cytotoxic T cell (CT) carbohydrate antigen. Both Galgt2 and the CT antigen are normally confined to the neuromuscular junction in mammalian skeletal muscle. The ectopic expression of the CT antigen in extrasynaptic regions of the myofiber membrane alters the expression of other normally synaptic proteins, including Synaptic laminins, utrophin, and neural cell adhesion molecule (NCAM), in transgenic mice. In addition, Galgt2 overexpression alters important aspects of muscle and neuromuscular development, and inhibits the formation of muscular dystrophy in mdx mice, a model for Duchenne muscular dystrophy. The principal protein that is glycosylated by Galgt2 in transgenic muscles is alpha dystroglycan, a major binding protein for the extracellular matrix (ECM). This grant will test a model wherein modification of dystroglycan by Galgt2 alters its properties and function. In addition, it will test mechanisms for altered laminin expression using muscle cells, transgenic mice, and gene knockout mice. These experiments will decipher mechanisms responsible for the functional roles of Galgt2 in muscle and neuromuscular development, as well as for its therapeutic role in muscular dystrophy.