Functions of BPAG1n

描述（由申请人提供）：神经营养因子支持中枢和外周神经元的存活、生长和分化。 神经营养因子的作用的高度特异性和保真度部分是由于它们对高亲和力细胞表面受体的激活。神经营养因子是第一个被鉴定的神经营养因子家族，以原型成员神经生长因子（NGF）为例，通过激活其受体酪氨酸激酶（RTK）Trks发挥功能。营养因子的第二家族，胶质细胞系衍生的神经营养因子（GDNF）家族配体（GFL），通过其RTK（Ret）的活化而发挥功能。我们最近已经确定了一个跨RTK信号传导机制，通过该机制激活的NGF受体，TrkA，导致在体外和体内的成熟依赖性激活Ret在没有GFLs。神经生长因子介导的Ret激活增强了成熟交感神经元的营养状态，但不影响未成熟交感神经元。为了确定神经生长因子促进Ret激活的机制，提出了旨在系统地测试最可能的假设的生化实验，利用体外维持的成熟交感神经元。识别神经生长因子促进Ret激活的机制对于形成一个长期项目至关重要，该项目旨在揭示哪些受体参与RTK间信号传导，以及该过程具有哪些发育功能。为了鉴定体内的GFL依赖性和GFL非依赖性（即NGF依赖性）Ret功能，将产生所有Ret功能或仅GFL依赖性Ret功能缺陷的转基因动物。对这些动物的中枢和外周神经系统的详细检查将首次揭示Ret的产后功能，因为Ret缺陷动物的围产期致死性不允许检查产后发育。作为主要研究者，我将学习重要的实验技能的新剧目，如在解剖，生理和行为水平的转基因动物的生产和分析，以及生产慢病毒载体表达外源蛋白在初级神经元。从这些拟议的实验结果，以及我将学习的技术，将提供一个坚实的基础，我追求我的职业目标，建立一个独立的研究计划，作为一个学术实验室的主要研究者。

DESCRIPTION (provided by applicant): Neurotrophic factors support the survival, growth, and differentiation of both central and peripheral neurons. The great specificity and fidelity of the effects of neurotrophic factors are due in part to their activation of high affinity cell surface receptors. The neurotrophins, the first identified family of neurotrophic factors exemplified by the prototypical member nerve growth factor (NGF), function via activation of their receptor tyrosine kinases (RTKs), the Trks. A second family of trophic factors, the glial cell-line derived neurotrophic factor (GDNF) family ligands (GFLs), function via activation of their RTK, Ret. We have recently identified an inter-RTK signaling mechanism by which activation of the NGF receptor, TrkA, leads both in vitro and in vivo to the maturation-dependent activation Ret in the absence of GFLs. NGF-mediated Ret activation augments the trophic status of mature, but not immature, sympathetic neurons. In order to identify the mechanism by which NGF promotes Ret activation, biochemical experiments designed to systematically test the most likely hypotheses are proposed, making use of mature sympathetic neurons maintained in vitro. The identification of the mechanism by which NGF promotes Ret activation is critically important for the formation of a long-term project to reveal which receptors participate in inter-RTK signaling, and what developmental functions this process has. In order to identify both the GFL-dependent and GFL-independent (i.e. NGF-dependent) Ret functions in vivo transgenic animals will be produced that are deficient in either all Ret functions, or in only GFL-dependent Ret functions. A detailed examination of the central and peripheral nervous systems of these animals will reveal, for the first time, the postnatal functions of Ret, given the perinatal lethality of Ret deficient animals that has not allowed examination of postnatal development. As the principle investigator I will learn a new repertoire of important experimental skills, such as the production and analysis of transgenic animals at the anatomic, physiologic, and behavioral levels, as well as the production of lentiviral vectors for the expression of foreign proteins in primary neurons. The results from these proposed experiments, as well as the techniques I will learn, will provide a solid basis for me to pursue my career objective to establish an independent research program as the principle investigator of an academic laboratory.