Regulation of auditory neuron neurite growth by activity

描述（由申请人提供）： 本申请的目标是将Marlan汉森博士培养为独立的医生/科学家。史蒂夫绿色和杰克利连博士将担任导师，以指导他的发展。Hanna Sobkowicz博士和艾伦瑞安博士将作为独立的外部评审员，以确保汉森博士的开发进度。共聚焦显微镜技术和应用，发育神经生物学和研究职业生存技能的正式课程将增加汉森博士的知识和技能，发展成为一个独立的调查员。 该提案的主要重点是一个密集的实验室经验，旨在确定电活动对螺旋神经节神经元（SGN）神经突生长和耳蜗的神经支配的影响。这包括确定活动依赖信号的必要性，以介导电活动的影响。大多数类型的感音神经性听力损失是由于毛细胞的损伤伴随着SGN的原发性或继发性损伤。耳蜗植入体通过向SGN提供直接电刺激来恢复最严重形式的感音神经性听力损失。电活动调节许多神经元中的神经突生长和神经支配模式。因此，电刺激对SGN神经突生长的影响对耳蜗发育、再生和植入具有重要影响。我们发现，膜去极化，Ca 2 +/钙调蛋白依赖性激酶II（CaMKII）的活性，和蛋白激酶A（PKA）的活性抑制SGN神经突起的生长。我们假设电刺激通过激活CaMKII和/或PKA抑制SGN神经突起生长。本提案的第一个目的是通过在分离培养物和耳蜗切片中向SGN提供不同速率的电刺激来定义电活动的生理模式对SGN神经突生长的影响。使用编码高度特异性CaMKII和PKA肽抑制剂的转基因，然后我们将确定通过电活性抑制神经突生长所需的CaMKII和PKA活性。组成型活性CaMKII和PKA突变体将被引入耳蜗切片中的SGN中，以测试这些分子在维持传入耳蜗神经支配中的作用。这些研究的结果将提供电活动对SGN神经突起生长和耳蜗神经支配的后果的关键数据。

DESCRIPTION (provided by applicant): The goal of this application is to develop Dr. Marlan Hansen into an independent physician/scientist. Drs. Steve Green and Jack Lilien will serve as mentors to guide his development. Drs. Hanna Sobkowicz and Allen Ryan will serve as independent outside reviewers to ensure the progress of Dr. Hansen's development. Formal coursework in confocal microscopy techniques and application, developmental neurobiology, and research career survival skills will increase Dr. Hansen's knowledge and skills to develop into an independent investigator. The principal focus of this proposal is an intensive laboratory experience aimed at determining the effects of electrical activity on spiral ganglion neuron (SGN) neurite growth and on the innervation of the cochlea. This includes determining the necessity of activity dependent signals to mediate the effects of electrical activity. Most types of sensorineural hearing loss result from damage to the hair cells accompanied by primary or secondary damage to the SGNs. Cochlear implants rehabilitate the most severe forms of sensorineural hearing loss by providing direct electrical stimulation to the SGNs. Electrical activity regulates neurite growth and innervation patterns in many neurons. Thus, the consequences of electrical stimulation on SGN neurite growth carry important implications for cochlear development, regeneration, and implantation. We find that membrane depolarization, Ca2+/calmodulin dependent kinase II (CaMKII) activity, and protein kinase A (PKA) activity inhibit SGN neurite growth. We hypothesize that electrical stimulation inhibits SGN neurite growth by activating CaMKII and/or PKA. The first aim of this proposal is to define the effects of physiological patterns of electrical activity on SGN neurite growth by providing different rates of electrical stimulation to SGNs in dissociated cultures and in cochlear slices. Using transgenes that encode highly specific CaMKII and PKA peptide inhibitors, we will then determine the requirement of CaMKII and PKA activity for the inhibition of neurite growth by electrical activity. Constitutively active CaMKII and PKA mutants will be introduced into SGNs in cochlear slices to test the role of these molecules in the maintenance of afferent cochlear innervation. The results of these studies will provide critical data on the consequences of electrical activity on SGN neurite growth and cochlear innervation.