The Role of Serine Protease Inhibitors in Nervous System Development

神经细胞通过被称为突触的特殊结构相互交流。在突触中，细胞通过像胶水一样的特殊蛋白质彼此固定在一起。在发育过程中，有必要去除或修饰这些粘附蛋白，这样神经分支才能生长，新的连接才能建立。当新记忆形成时，大脑中的一些突触也会发生类似的变化。粘附蛋白被称为蛋白酶的酶分解。蛋白酶由神经细胞产生，并在突触处释放。释放的蛋白酶不会以不受控制的方式降解突触蛋白。相反，它们会遇到其他被称为“蛇形蛋白”的蛋白质，这种蛋白质会抑制蛋白酶。因此，在蛇蛋白水平高的区域，蛋白酶活性降低。蛇形蛋白是由哺乳动物和无脊椎动物的多种神经细胞形成的。例如，人类大脑中最常见的蛇形蛋白（神经蛇形蛋白）与果蝇大脑中发现的被称为Spn4的蛇形蛋白密切相关。在这个提议中，PI将检查果蝇神经细胞和肌肉之间的突触。在这些突触中发现了Spn4，我们假设它抑制了一种或多种参与突触正常发育的蛋白酶。Spn4在神经-肌肉突触的发育和功能中所起的作用将在发育过程中蛋白质量增加或减少的情况下进行研究。该项目将研究神经系统活动如何通过各种基因突变影响Spn4的数量或功能。最后，PI将识别被Spn4抑制的蛋白酶。拟议活动的更广泛影响：教育和外展。该研究员在培养本科生、研究生和博士后研究员方面有丰富的经验，包括来自代表性不足的少数群体的成员（包括本提案中的一名研究生）。他鼓励本科生进行研究，包括发表由NSF资助的论文（1名本科生第一作者，1名共同作者）。该项目将支持学生在细胞神经生物学、神经发育和遗传学领域的持续培训，为他们从事高级科学事业做好准备。研究界：实验室开发的许多试剂和转基因品系具有广泛的用途，并且对研究人员免费提供，进一步促进了科学探索。最后，关于控制突触发育和可塑性的分子和细胞机制的基本知识为开发未来对社会普遍有益的神经生物学应用提供了坚实的基础。

Nerve cells communicate with each other at specialized structures known as synapses. At the synapse cells are anchored to each other by specialized proteins that function like glues. During development it is necessary to unstick or modify these adhesive proteins, so that nerve branches can grow and new connections can be made. Similar changes occur at some synapses in the brain when new memories are formed.The adhesive proteins are broken down by enzymes known as proteases. The proteases are made by nerve cells and are released at the synapse. The released proteases do not degrade synaptic proteins in an uncontrolled fashion. Instead, they encounter other proteins known as "serpins", which inhibit the proteases. Thus, in areas where serpin levels are high, the protease activity is reduced. Serpins are made by many kinds of nerve cell, both in mammals and in invertebrates. For example, the most common serpin of the human brain (Neuroserpin) is closely related to the serpin found in the brain of the fruit fly Drosophila, known as Spn4. In this proposal the PI will examine the synapses made between nerve cells and muscles in Drosophila. Spn4 is found at these synapses, where we hypothesize that it inhibits one or more proteases involved in the normal development of the synapse.The role that the Spn4 plays in both the development and function of nerve-muscle synapses will be examined in situations where the amount of the protein is either increased or reduced during development. This project will examine how nervous system activity influences the amount or function of Spn4 using various genetic mutations. Finally, the PI will identify the proteases that are inhibited by Spn4. Broader Impacts of Proposed Activity: Education and outreach. The investigator has extensive experience training undergraduates, graduate students, and postdoctoral fellows, including members from underrepresented minority groups (including one graduate student in this proposal). He encourages undergraduate research, including publication of papers supported by the previous NSF funding (1 undergraduate first author, 1 coauthor). The project will support the continued training of students in the areas of cellular neurobiology, neural development, and genetics, preparing them for advanced scientific careers. Research community: Many of the reagents and transgenic lines developed in the lab are of widespread utility, and are freely available to researchers, furthering scientific inquiry. Finally, fundamental knowledge about the molecular and cellular mechanisms governing of synaptic development and plasticity provides a firm foundation for developing future neurobiological applications of general benefit to society.