The role of BDNF in taste receptor cell innervation

描述(申请人提供)：神经营养因子(BDNF)是 味蕾的发育和适当的神经支配。口感分析 野生型和高表达转基因小鼠模型中的系统研究表明，BDNF 至少在一定程度上，作为一种靶向因子，调节轴突靶向 和神经支配密度。在胚胎早期，脑源性神经营养因子在 菌状乳头上皮。胚胎后期脑源性神经营养因子的表达 在舌头中变得集中，只在包括发育中的细胞中发现 味蕾。这种精细的表达模式表明，BDNF的合成是通过 味蕾细胞对正常的味觉神经支配至关重要。为了支持这一点 有可能，我们发现过表达BDNF的转基因小鼠 整个舌上皮严重破坏了味蕾的神经支配和 较少的味蕾，即使这些小鼠有更多的味觉(膝曲) 神经元。我们现在建议推进这一分析，并测试BDNF水平如何 味蕾本身会影响神经元的存活和神经支配。这将是 使用了一种新的转基因小鼠模型，在该模型中，角蛋白19基因启动子 将用于靶向BDNF基因在味蕾受体细胞中的表达。 将使用在味觉细胞中过表达K19的转基因小鼠(K19-BDNF小鼠) 研究靶基因衍生的BDNF如何调节味蕾发育和 神经支配。具体来说，我们将使用RT-PCR、原位杂交、逆行 标记和确定是否增强表达的基本组织学方法 BDNF在味觉细胞中的作用，1)增加对菌状乳头的神经支配，2) 增加菌状乳头中味蕾的大小或数量，3)干扰 味蕾大小和神经支配之间存在正相关关系，以及 4)提高胶状神经节细胞存活率。这些鼠标还将提供一种 研究受体机制和内部信号转导的有价值的模型 BDNF在味觉发育中的作用途径。这 该方法提供了一种新的强大的手段来操纵基因的表达。 味觉末端器官，允许研究调节味觉的内在因素 器官发育和神经支配。

DESCRIPTION (provided by applicant): The neurotrophin (BDNF) is essential for the development and proper innervation of taste buds. Analysis of the taste system in wildtype and overexpresser transgenic mouse models has shown that BDNF acts, at least in part, as a target-derived factor that modulates axon targeting and innervation density. During early embryonic periods, BDNF is expressed in the epithelium of fungiform papillae. By later embryonic times BDNF expression in the tongue becomes focused and is only found in cells comprising developing taste buds. This refined expression pattern suggests that BDNF synthesis by taste bud cells is crucial for normal taste innervation. In support of this possibility, we found that transgenic mice that overexpress BDNF across the entire tongue epithelium had severely disrupted innervation to taste buds and fewer taste buds, even though these mice had more gustatory (geniculate) neurons. We now propose to advance this analysis and test how the level of BDNF in the taste bud itself affects neuron survival and innervation. This will be done using a new transgenic mouse model in which the keratin 19-gene promoter will be used to target BDNF gene expression to receptor cells of taste buds. Transgenic mice that overexpress K19 in taste cells (K19-BDNF mice) will be used to examine how target-derived BDNF modulates taste bud development and innervation. Specifically, we will use RT-PCR, in situ hybridization, retrograde labeling, and basic histological approaches to determine if enhanced expression of BDNF in taste cells, 1) increases innervation to fungiform papillae, 2) increases the size or number of taste buds in fungiform papillae, 3) disrupts the positive co-relation that exists between taste bud size and innervation, and 4) increases gelliculate ganglion cell survival. These mice will also provide a valuable model for studies on the receptor mechanisms and internal signaling pathways that underlie the action of BDNF in gustatory development. This approach provides a new and powerful means to manipulate gene expression in the taste end organs, allowing study of the intrinsic factors that regulate taste organ development and innervation.