CORE--TRANSGENIC MICE

神经营养因子在发育过程中对三叉神经感觉神经元存活的作用现在已经得到了很好的证实。以前使用神经营养因子无效突变体和转基因小鼠的研究增加了我们对神经营养因子的理解。然而，在这些模型中，启动子驱动的神经营养因子表达的致死性和控制不良使得不可能表征神经营养因子对三叉神经感觉神经元的替代作用。该核心的作用是产生转基因模型，其中神经营养因子的表达可以在特定时期内在三叉神经感觉神经元的外周或中枢靶点中诱导。该核心将利用靶特异性启动子与新开发的RevTet-On系统（Clonetech）组合，以诱导NGF、NT-3和BDNF在三叉神经相关靶组织中的过表达。RevTet-On系统采用双构建体系统，其产生两个转基因小鼠系，当将其繁殖在一起时，产生具有由四环素施用诱导的靶特异性转基因表达的“双基因”小鼠。一些项目要求小鼠在皮肤（NGF，NT-3）、面骨骼肌（NT-3）和脑干/皮质（NGF，NT-3，BDNF）中过度表达神经生长因子（NGF）、神经营养因子-3（NT-3）和脑源性神经营养因子（BDNF）。核心B将产生并注射指定的转基因构建体，然后表征创始小鼠以鉴定合适的品系。核心B将繁殖小鼠品系以产生双基因小鼠。将在mRNA和蛋白质水平上评价调节的神经营养因子转基因表达，并提供小鼠。这种方法的优点是，神经营养因子的行动可以在体内研究在确定的阶段，在没有神经营养因子调节三叉神经存活的复杂影响。此外，颅面组织可以被置于培养物中，并且神经营养因子的合成可以在内源性靶组织中被诱导。由该核心产生的小鼠的结果将提供关于神经营养的新生物学信息，可以揭示现在操纵神经元的营养支持将有助于治疗涉及颅面感觉系统的病理性神经疾病。

The actions of neurotrophins on the survival of trigeminal sensory neurons during development is now well established. Previous studies using neurotrophin null mutant and transgenic mice have added to our understanding of neurotrophins. However, lethality and poor control of promoter-driven neurotrophin expression in these models has made it impossible to characterize alternative actions of neurotrophins on trigeminal sensory neurons. The role of this Core is to generate transgene models in which neurotrophin expression can be induced in peripheral or central targets of trigeminal sensory neurons during specified periods. This Core will utilize target specific promoters in combination with the newly developed RevTet-On system (Clonetech) to induce the over-expression of NGF, NT-3 and BDNF in trigeminally-relevant target tissues. The RevTet-On system employs a two construct system which yields two transgenic mouse lines that when bred together, generate "bigenic" mice with target- specific transgene expression induced by tetracycline administration. Some Projects requ7ire mice that over-express nerve growth factor (NGF), neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF) in skin (NGF, NT-3), facial skeletal muscle (NT-3) and brainstem/cortex (NGF, NT-3, and BDNF). Core B will generate and inject specified transgene constructs, and then characterized founder mice to identify the suitable lines. Core B will breed mouse lines to generate bigenic mice. Regulated neurotrophin transgene expression will be evaluated at mRNA and protein levels and mice will be made available. The advantage of this approach is that the actions of neurotrophins can be studied in vivo at defined stages in the absence of the complicating effects of neurotrophin-regulated trigeminal survival. Also, craniofacial tissues can be placed in culture and neurotrophin synthesis can be induce din endogenous target tissues. Results from mice generated by this Core will provide new biological information about neurotrophic can reveal now manipulation of the trophic support of neurons will be useful to treat pathologic neural conditions involving craniofacial sensory systems.