Role of XIRP2 in hair cell function and degeneration

XIRP2 在毛细胞功能和退化中的作用

基本信息

批准号：
8957404
负责人：
Jung-Bum Shin
金额：
$ 33.6万
依托单位：
UNIVERSITY OF VIRGINIA
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-12-01 至 2019-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8957404
关键词：
Actinin Actins Address Adherens Junction Age Binding Cell Maintenance Cell physiology Cellular Structures Clustered Regularly Interspaced Short Palindromic Repeats Complement Complex Coupling Defect Development Environmental Risk Factor Epithelial Exhibits Exons F-Actin Genes Genetic Goals Hair Hair Cells Health Hearing Heart High-Frequency Hearing Loss Human Intercellular Junctions Knockout Mice Labyrinth Light Location Maintenance Mass Spectrum Analysis Mechanical Stress Mechanics Mediating Membrane Microfilaments Mus Mutation Myocardium Neoplasms Noise Noise-Induced Hearing Loss Overlapping Genes Pathway interactions Peripheral Phenotype Play Protein Isoforms Proteins Proteome Proteomics RNA Splicing Receptor Cell Regulation Role Sensory Hair Sequence Homology Side Stereocilium Stress Tests Structural defect Structure Supporting Cell Technology Tertiary Protein Structure Testing Time Transgenic Mice base deafness depolymerization hearing impairment novel null mutation prevent research study

项目摘要

DESCRIPTION (provided by applicant): Our long-term goal is to understand the mechanisms that underlie the development, maintenance and degeneration of the mechanosensory hair bundle. Motivated by the fact that a third of all known deafness genes encode hair bundle proteins, we previously used a mass spectrometry based strategy to characterize the hair bundle proteome. This approach proved to be a powerful complement to traditional genetics strategies, leading to the discovery of novel deafness genes previously undetected using genetic strategies alone. For further analysis, we focused on proteins for which the corresponding gene locations overlap with unresolved human deafness loci. One such protein is XIRP2 (for xin actin-binding repeat containing protein 2). In this project, we are testing the hypothesis that XIRP2 is a novel hair cell protein required for long-term stability of stereocilia and the hair cell/supporting cell junctions, with the consequence that XIRP2 deficiency causes hair cell degeneration and progressive hearing loss. Preliminary studies demonstrated that different XIRP2 splice forms are present in the hair cell, displaying distinct localizations in the stereocilia and pericuticular adherens junctions, respectively. To explore the role of XIRP2 for hearing function, we used the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas technology to generate transgenic mice with a functional null mutation in the Xirp2 gene and found evidence for high-frequency hearing loss. In Specific Aim 1, we will investigate the hearing loss phenotype in Xirp2 null mice in detail. Furthermore, we will test whether XIRP2 deficiency renders the hair cell more sensitive to mechanical stress, by testing the sensitivity of Xirp2 null mice to noise-induced hearing loss. Preliminary studies suggested that the stereocilia and the adherens junctions harbor distinct XIRP2 isoforms, implying that defects in either hair cell structure could underlie the observed hearing loss in Xirp2 null mice. n Aim 2 and 3, we will therefore use transgenic mice with isoform specific deletions in the Xirp2 gene, to specifically address their contribution to hair cell degeneration and hearing loss. Our hypothesis that XIRP2 is required for long-term maintenance of hair cell structures dovetails well with its known role in cardiac muscle, where it is involved in the maintenance of the sarcomeric Z-line. XIRP2's role in the hair cell is likely to be distinct from and more complex than its functon in the heart: the hair bundle harbors a novel isoform with vastly different protein domain structure, rendering it practically an unknown protein. Significant for human hearing health, understanding the role of XIRP2 in hair cell degeneration is expected to shed light on mechanisms by which subtle defects caused by genetic and environmental factors can compromise the structural integrity of hair cell structures, significant for understanding the mechanistic basis of age and noise-induced hearing loss. Finally, the chromosomal locus of the XIRP2 gene overlaps with the human deafness loci DFNB27 and DFNA16, opening up the prospect of identifying the causative mutation for two human deafness phenotypes.

描述（由申请人提供）：我们的长期目标是了解机械感知头发束的开发，维护和变性的机制。由于所有已知的耳聋基因中的三分之一编码了毛发束蛋白的动机，我们以前使用了基于质谱的策略来表征头发束蛋白质组。这种方法被证明是对传统遗传学策略的有力补充，从而导致仅使用遗传策略未发现的新型耳聋基因。为了进一步分析，我们专注于相应基因位置与未解决的人耳聋基因座重叠的蛋白质。一种这样的蛋白质为XIRP2（用于XIN肌动蛋白结合重复含有蛋白2）。在这个项目中，我们正在测试以下假设：XIRP2是立体胶质和毛细胞/支撑细胞连接的长期稳定性所需的新型毛细胞蛋白，结果XIRP2缺乏会导致毛细胞变性和进行性听力损失。初步研究表明，毛细胞中存在不同的XIRP2剪接形式立体胶质和周围粘附连接处分别。为了探索XIRP2在听力功能中的作用，我们使用了CRISPR（群集定期间隔短的短粒子重复序列）/CAS技术在XIRP2基因中产生具有功能性无效突变的转基因小鼠，并找到了高频率听力损失的证据。在特定目标1中，我们将详细研究XIRP2无效小鼠中的听力损失表型。此外，我们将通过测试XIRP2 null小鼠对噪声引起的听力损失的敏感性来测试XIRP2缺乏是否对机械应力更敏感。初步研究表明，立体膜和粘附连接处具有独特的XIRP2同工型，这意味着任何一种毛细胞结构的缺陷都可能是XIRP2 NULL小鼠观察到的听力损失的基础。 n AIM 2和3，我们将使用XIRP2基因中具有同工型特异性缺失的转基因小鼠，以特别解决它们对毛细胞变性和听力损失的贡献。我们的假设是，XIRP2是长期维持毛细胞结构所必需的，它与其在心脏肌肉中的已知作用很好地吻合，在那里它参与了肉瘤Z线的维持。 XIRP2在毛细胞中的作用可能与其在心脏中的功能子相比，可能与其具有较大蛋白质结构结构的新型同工型相比，与其功能相比，它与其功能相比更为复杂，更为复杂。对于人类的听力健康而言，了解XIRP2在毛细胞变性中的作用有望阐明遗传和环境因素引起的细微缺陷会损害毛细胞结构的结构完整性，这对于理解年龄和噪声诱发的听力损失的机械基础很重要。最后，XIRP2基因的染色体基因座与人耳聋基因座DFNB27和DFNA16重叠，开辟了鉴定两种人耳聋表型的病因突变的前景。