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很清楚了。以前使用神经营养因子缺失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了解。然而，在这些模型中，致命性和对启动子驱动的神经营养因子表达的不良控制使得神经营养因子在三叉神经感觉神经元上的替代作用不可能被表征。这个核心的作用是产生转基因模型，在该模型中，神经营养素可以在特定时期内在三叉神经感觉神经元的外周或中央靶点诱导表达。这个核心将利用目标特定的启动子与新开发的RevTet-on系统(Clonetech)相结合，在三叉神经相关的目标组织中诱导NGF、NT-3和BDNF的过度表达。RevTet-On系统采用双构建系统，产生两个转基因小鼠系，当它们一起饲养时，产生由四环素注射诱导的靶标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)、面部骨骼肌(NT-3)和脑干/皮质(NGF、NT-3和BDNF)过表达神经生长因子(NGF)、神经营养素-3(NT-3)和脑源性神经营养因子(BDNF)。核心B将产生并注入特定的转基因构建物，然后对创始人小鼠进行鉴定，以确定合适的品系。核心B将培育小鼠品系，以产生双基因小鼠。将在mRNA和蛋白质水平上评估受调控的神经营养因子转基因表达，并将提供小鼠。这种方法的优点是，在没有神经营养因子调节的三叉神经存活的复杂影响的情况下，可以在体内确定的阶段研究神经营养因子的作用。此外，可以将颅面组织置于培养环境中，并在内源性靶组织中诱导神经营养素合成。由该核心产生的小鼠的结果将提供关于神经营养的新的生物学信息，可以揭示现在对神经元的营养支持的操作将有助于治疗涉及头面部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.