Molecular Mechanisms of Cellular Differentiation in the Nervous System

描述（由申请人提供）：本提案的主要目标是了解发育中的神经系统中神经元和胶质细胞分化的分子基础。本文将研究脊髓内单个祖结构域（pMN）控制序列运动神经元和少突胶质细胞分化的机制。GDE2是一种六跨膜（6-TM）蛋白，含有胞外甘油磷酸二酯磷酸二酯酶（GDPD）结构域，是通过GDPD活性诱导运动神经元分化的必要和充分条件。在本研究中，将采用生物化学和体内方法来确定GDE2 GDPD活性的机制，并确定6- TM GDPD酶功能的潜在生理底物。引人注目的是，第二个6-TM GDE蛋白与GDE2互补表达，与少突胶质细胞的产生一致。将采用体内和体外方法来测试第二GDPD调节系统在少突胶质细胞规范、分化和成熟中的功能。基因消融GDE2导致胶质形成期少突胶质细胞数量增加，提示GDE2可能阻止少突胶质细胞过早开始分化。这一假设将得到验证

DESCRIPTION (provided by applicant): The major goals of this proposal are to understand the molecular basis of neuronal and glial differentiation in the developing nervous system. Here, the mechanisms that control sequential motor neuron and oligodendrocyte differentiation from a single progenitor domain (pMN) within the spinal cord will be investigated. GDE2, a six-transmembrane (6-TM) protein that contains an extracellular glycerophosphodiester phosphodiesterase (GDPD) domain is necessary and sufficient to induce motor neuron differentiation through GDPD activity. In this proposal, biochemical and in vivo approaches will be used to define the mechanism of GDE2 GDPD activity and identify potential physiological substrates of 6- TM GDPD enzymatic function. Strikingly, a second 6-TM GDE protein shows complementary expression to GDE2 that is coincident with oligodendrocyte generation. In vivo and in vitro approaches will be taken to test the function of this second GDPD regulatory system in oligodendrocyte specification, differentiation and maturation. Genetic ablation of GDE2 results in increased numbers of oligodendrocytes in the gliogenic period, suggesting that GDE2 might prevent the premature initiation of oligodendrocyte differentiation. This hypothesis will be tested using a combination of biochemical, genetic and functional approaches. Taken together, these studies will provide mechanistic insight into novel GDPD-dependent regulatory systems that control motor neuron and oligodendrocyte differentiation, and determine if they intersect to regulate the temporal control of neurogenesis and gliogenesis in the spinal cord.