PLASTICITY IN THE AGING OLFACTORY SYSTEM

描述(改编自《调查者摘要》)：嗅觉 受体上皮在成年动物中表现出再生能力， 它的中枢神经系统目标需要持续的可塑性， 嗅球。酪氨酸羟基酶(TH)，人体内的限速酶 儿茶酚胺的生物合成存在于多巴胺能(DA)肾小球周围 调节嗅球传入刺激的嗅球固有细胞 二尖瓣细胞。在整个生命过程中，TH在DA神经元中的表达表现为 模式嗅觉刺激(气味)介导的深刻调控 STIM.)。调控TH表达的机制还有待于分析 嗅球，尤其是在基因水平上。调查人员 假设嗅觉导致一系列事件，包括 转录因子的合成和/或磷酸化，以维持 基因表达。提出了四个具体目标，以解决 参与TH基因调控的顺式作用元件。目标1将 利用凝胶迁移率变化、RT-PCR和DNA足迹技术 鉴定小鼠体内特异调控的转录因子 嗅球。差异显示将被用来识别基因 与TH并行地表现出改变的规则。AIM 2将在体内使用 转基因小鼠技术鉴定上游结合结构域 足以满足嗅觉中正常和调节的TH表达 灯泡。AIM 3将使用体内标记技术来定位改变 转录因子在模型系统DA神经元中的表达 表现出修饰的TH基因表达。差异化，无气味 幼年动物和老年动物以及转基因小鼠 嗅觉标记蛋白将用于研究基因调控 TH表达改变的动物。目标4将使用不朽的和 新生鼠嗅球原代细胞培养及其对细胞生长的影响 在受控条件下的表达，并将这些变化与 转录因子的表达。总而言之，这些实验将 开始定义调控TH基因表达的分子机制 嗅球。因为TH的表达是一个明确的指标 嗅觉传入神经的完整性，这些发现不会影响 仅限于了解该酶的调节，但一般情况下 嗅球功能的跨突触控制。拟议的研究将 从而提供了对导致可塑性改变的机制的洞察 老化的嗅觉系统。因此，这项研究项目解决了 在这两种情况下观察嗅觉功能受损的病因 正常衰老和退行性疾病，如阿尔茨海默氏症和 帕金森氏症。

DESCRIPTION (Adapted from the Investigator's Abstract): The olfactory receptor epithelium displays regenerative capacity in adult animals, requiring continuous plasticity within its central nervous system target, the olfactory bulb. Tyrosine hydroxylase (TH), the rate limiting enzyme in catecholamine biosynthesis is found in dopaminergic (DA) periglomerular cells intrinsic to the olfactory bulb that regulate afferent stimulation of mitral cells. Throughout life, TH expression in the DA neurons exhibits profound regulation mediated by patterned olfactory stimulation (odorant stim.). The mechanisms regulating TH expression have yet to be analyzed in the olfactory bulb especially at the gene level. The investigators hypothesize that olfaction results in a cascade of events involving synthesis and/or phosphorylation of transcription factors that maintain TH gene expression. Four specific aims are proposed that will address the cisand transacting elements involved in TH gene regulation. Aim 1 will utilize gel mobility shift, RT-PCR and DNA footprinting techniques to identify the transcription factors specifically regulated in the mouse olfactory bulb. Differential display will be used to identify genes exhibiting altered regulation in parallel with TH. Aim 2 will use in vivo transgenic mouse techniques to identify upstream binding domains that are sufficient for both normal and regulated TH expression in the olfactory bulb. Aim 3 will use in vivo labeling techniques to localize altered expression of transcription factors in DA neurons in model systems exhibiting modified TH gene expression. Differentiated, odorant deprived young and aged animals as well as transgenic mice null for expression of olfactory marker protein will be used to investigate gene regulation in animals with altered TH expression. Aim 4 will employ immortalized and primary cell cultures derived from neonatal olfactory bulb to modify TH expression under controlled conditions and correlate those changes with expression of transcription factors. Collectively, these experiments will begin to define the molecular mechanisms regulating TH expression in the olfactory bulb. Because expression of TH is a definitive indicator of the integrity of olfactory afferent innervation, these findings will impact not only on understanding regulation of this enzyme, but generally on transsynaptic control of olfactory bulb function. The proposed studies will thus provide insight into the mechanisms underlying altered plasticity in the aging olfactory system. Hence, this research project addresses the etiology underlying compromised olfactory function observed during both normal aging and in degenerative disorders such as Alzheimer's and Parkinson's disease.