NEUROGENESIS IN THE AUDITORY SYSTEM

描述（申请人提供）：内耳和耳蜗神经损伤引起的耳聋和听力损失仍然是当今主要的无法治愈的疾病。同样令人担忧的是先天性的损害，因为由此导致的听力障碍严重影响了沟通技巧和学习能力的发展。这些情况与中枢听觉通路的退化和重组有关。为了更好地了解这些情况，我们需要了解听觉通路发育中轴突生长和突触形成的因素，因为在正常发育、先天性畸形和成熟神经系统的可塑性变化中，这些过程可能涉及相同的遗传因素。本研究旨在阐明导致内耳感觉神经结构组装的细胞相互作用及其与中央听觉通路的联系。方法是通过显微镜观察耳蜗神经节细胞在正常发育过程中的形态发生，研究某些关键分子（生长因子及其受体）在耳蜗神经节细胞分化中的作用。将对它们的胚胎前体及其靶组织（即感觉上皮和耳蜗核）进行实验扰动，以测试有关这些关键分子作用的遗传假设。用鸡和小鼠胚胎及新生儿的耳前体细胞和听核细胞培养物来表征细胞相互作用。用单基因缺失或过表达诱导的基因突变模型与正常小鼠进行比较。实验旨在揭示参与这些相互作用的关键因素及其在分子水平上的作用位点。抗体和原位杂交将用于在原位发育过程的关键阶段将这些分子定位到特定的细胞类型。对培养的小鼠耳蜗神经节细胞进行实验扰动，包括用生长因子、抗体和转染的核酸处理，以评估它们与胚胎和新生动物的耳蜗核和内耳的相互作用。来自正常和转基因小鼠胚胎的感觉神经元前体和耳上皮的共培养将用于确定具有特定遗传改变的细胞如何受到影响。最终，这些发现应该为开发新疗法提供合理的基础。

DESCRIPTION (provided by applicant): Deafness and hearing loss due to damage of the inner ear and cochlear nerve remain as major incurable disorders today. Also of much concern are congenital forms of damage, since the resulting hearing impairment profoundly disturbs the development of communication skills and learning. These conditions are associated with degeneration and reorganization of the central auditory pathways, To understand better these conditions, we need to acquire some insight into the factors that account for axonal growth and synapse formation in the development of the auditory pathway, since the same genetic factors are likely to be involved in these processes during normal development, congenital malformation, and plastic changes in the mature nervous system. This research aims to elucidate the cellular interactions leading to the assembly of the sensorineural structures of the inner ear and the connections with the central auditory pathway. The approach is to study the role of certain key molecules (growth factors and their receptors) in the differentiation of the cochlear ganglion cells by microscopic observations of their morphogenesis during normal development. Experimental perturbations of their embryonic precursors and their target tissues, i.e., the sensory epithelium and cochlear nucleus, will be carried out to test genetic hypotheses concerning the role of these key molecules. Cell cultures of the precursors of the ear and acoustic nuclei of chicken and mouse embryos and neonates are used to characterize the cellular interactions. Induced genetic mutants with single gene deletions or overexpression models are compared with normal mice. Experiments are designed to reveal key factors involved in these interactions and the loci of their actions at the molecular level. Antibodies and in situ hybridization will be used for localizing such molecules to specific cell types at the critical stages of the developmental process in situ. Experimental perturbations of cultured mouse cochlear ganglion cells, including treatment with growth factors, antibodies, and transfected nucleic acids will be used to evaluate their interactions with the cochlear nucleus and inner ear of embryonic and neonatal animals. Co-cultures of sensory neuronal precursors and otic epithelium from normal and genetically modified mouse embryos will be used to determine how cells with specific genetic alterations are affected. Ultimately these findings should provide a rational basis for developing new therapies.