Cellular Interactions During Ear Development

描述(申请人提供)：在本申请中，我们希望解决导致耳朵两种主要感觉神经细胞类型形成的一些分子和细胞相互作用，毛细胞用于机械电转导，感觉神经元用于将信息从毛细胞传导到大脑。我们将使用形态学方法(例如免疫组织化学和DiI标记)和分子生物学方法(例如原位杂交和RT-PCR)来分析1)细胞存活、2)一般细胞命运测定和3)器官特定细胞命运测定。 在目标1中，我们将仔细研究神经营养素的位置和数量在模式内耳神经支配中所起的作用。内耳感觉神经元表达trkB和trkC受体。这一独特的功能将使我们能够在体内首次分析同时携带神经营养因子转基因(NT3 TgBDNF)的BDNF缺失突变体中神经营养因子的浓度和分布如何影响正常和异常神经纤维的模式。在……里面 目的2我们将研究在耳朵中表达的主要神经源性bHLH基因：Ngn1、Math1和NeuD的分子和细胞相互作用。我们将研究感觉神经元和毛细胞之间可能的克隆关系，以及不同的前神经元bHLH基因组合的缺失如何影响耳朵发育，特别是支持细胞中的基因表达模式。与大脑相比，这种分析是可行的，因为只有两个bHLH基因(Math1，Ngn1)决定了两个神经元样细胞(毛细胞和感觉神经元)。我们将对Ngn1、Math1和Neurd的突变体进行杂交，以研究Ngn1如何影响Math1，Ngn1如何影响NeuroD，Math1如何影响NeuroD，以及Ngn1和Math1的双重空值如何影响剩余耳朵的形成。 在目标3中，我们将分析BF1和FGF10如何影响器官特异性感觉神经元和感觉上皮的形成，这些突变体中没有这些突变体。我们将鉴定bHLH基因Ngn1和Math1在BF1和FGF10零突变体中的表达。这些信息可以指导未来对感觉神经性听力损失患者和其他神经科学领域不太适合此类研究的患者的这些细胞再生的研究。

DESCRIPTION (provided by applicant): In this application we want to resolve some of the molecular and cellular interactions that lead to the formation of the two main sensorineuronal cell types of the ear, the hair cell for mechanoelectric transduction and the sensory neurons for conduction of information from the hair cells to the brain. Using morphological (e.g. immunohistochemistry and DiI labeling) and molecular biological approaches (e.g. in situ hybridization, and RTPCR) we will analyze aspects of 1) cell survival, 2) general cell fate determination, and 3) organ specific cell fate determination. In AIM 1 we will scrutinize the role played by both location and amount of neurotrophin expression in patterning inner ear innervation. Inner ear sensory neurons express both trkB and trkC receptors. This unique feature will allow us to analyze in a BDNF null mutant simultaneously carrying a neurotrophin transgene (NT3 tgBDNF) for the first time in vivo how both concentration and distribution of a neurotrophin affect the patterning of normal and aberrant nerve fibers. In AIM 2 we will examine the molecular and cellular interactions of the principle neurogenic bHLH genes expressed in the ear; ngn1, Math1 and NeuroD. We will examine a possible clonal relationship between sensory neurons and hair cells and how the absence of varying combinations of proneuronal bHLH genes affects ear development, in particular the gene expression patterns in supporting cells. In contrast to the brain, this analysis is feasible because only two bHLH genes (Math1, ngn1) determine two neuron-like cells (hair cells, sensory neurons). We will interbreed mutants of ngn1, Math1, and NeuroD to study how ngn1 affects Math1, how ngn1 affects NeuroD, how Math1 affects NeuroD and how double nulls for both ngn1 and Math1 affect formation of the remaining ear. In AIM 3 we will analyze how BF1 and FGF10 affect the formation of organ specific sensory neurons and sensory epithelia absent in these mutants. We will characterize the expression of the bHLH genes, ngn1 and Math1, in null mutants of BF1 and FGF10. Such information can guide future research on regeneration of these cells in patients suffering sensorineuronal hearing loss and other areas of neuroscience less amenable to such investigations.