MOLECULAR BASIS OF TROPHIC INTERACTION IN SYNAPTOGENESIS

了解突触发育的机制将是 理解遗传和环境影响的核心 因素（包括药物）对胎儿和幼儿。 的 神经-肌肉突触在体内和组织中的发育 培养是CNS突触发育的有价值的模型。 一 这种神经肌肉突触发育的显着特征是 烟碱乙酰胆碱受体聚集体的形成 （AChR）在突触后膜。 至少在某些物种中， 乙酰胆碱受体插入细胞膜的速率增加 在新生突触的位置， 对形成这种聚集体的贡献。 A 42 kD蛋白 现在已经被纯化（Usdin和Fischbach，1986）， 鸡脑，当其浓度达到 0.5ng/ml时，AChR参入率增加 进入培养的鸡肌管的膜中， AChR聚集体的数量。 这种蛋白质可以通过 神经肌肉接触部位的脊髓运动神经元， 诱导突触特化。 该项目的目的是 研究该蛋白的生物学作用及其机制 的行动。 具体目标是： 1)纯化足够的42 kD乙酰胆碱受体诱导 活性（42 kD ARIA），以提供生产 抗体、氨基末端序列的测定和研究 这种蛋白质的生物学特性。 2)产生针对以下的单克隆和多克隆抗体： 42kD ARIA 3)使用这些抗体试剂来研究生物学作用 这种蛋白质。 一个关键问题是抗体是否 直接针对这种蛋白质， 神经肌肉接触部位的特化。 这将是 在体外和体内研究。 的区域分布 42 kD ARIA将使用免疫荧光进行研究， 将开发ELISA测定法以定量42 kD的水平 艾瑞亚 局部应用这种蛋白质对 还将检查肌管。 4)长期目标包括确定完整的氨基酸 42 kD ARIA的序列，并研究其对 AChR亚单位的合成和亚单位mRNA水平。

Understanding the mechanisms of synaptic development will be central to understanding the effects of genetic and environmental factors (including drugs) on the fetus and young child. The development of the nerve-muscle synapse in vivo and in tissue culture is a valuable model of CNS synaptic development. A striking feature of this nerve-muscle synapse development is the formation of an aggregate of nicotinic acetylcholine receptors (AChR) in the postsynaptic membrane. In at least some species, an increase in the rate of insertion of AChRs into the membrane at the site of the nascent synapse makes an important contribution to the formation of this aggregate. A 42kD protein has now been purified (Usdin and Fischbach, 1986) from the chicken brain which, when present at a concentration on the order of 0.5ng/ml, causes an increase in the rate of AChR incorporation into the membrane of cultured chick myotubes and also in the number of AChR aggregates. This protein might be released by the spinal motor neuron at the site of nerve-muscle contact and induce synaptic specializations. The purpose of this project is to investigate the biological role of this protein and its mechanism of action. The specific aims are: 1) Purify enough of the 42kD acetylcholine receptor inducing activity (42kD ARIA) to provide amounts needed for production of antibodies, determination of amino-terminal sequence, and studies of the biological properties of this protein. 2) Raise monoclonal and polyclonal antibodies directed against this 42kD ARIA. 3) Use these antibody reagents to investigate the biological role of this protein. A key question is whether or not antibodies directed against this protein block the formation of synaptic specializations at sites of nerve-muscle contact. This will be investigated in vitro and in vivo. The regional distribution of the 42kD ARIA will be studied using immunofluorescence, and an ELISA assay will be developed to quantitate levels of the 42kD ARIA. The effect of focal application of this protein onto myotubes will also be examined. 4) Long-term goals include determining the full amino acid sequence of the 42kD ARIA and studying its affect on the rate of synthesis of AChR subunits and on subunit mRNA levels.