申请者通过家系研究自主发现了一个耳聋新致病基因DMXL2，其p.R1417H突变可导致常染色体显性遗传性耳聋，但该基因在内耳的具体功能和致聋机制不明。我们发现携带DMXL2突变的病人具有和听神经突触病变相关的隐蔽性听力损失特征，且该基因特异性高表达于小鼠内毛细胞基底部的带状突触活跃区域，提示DMXL2可能与毛细胞突触功能相关。课题组已成功构建具有类似听力障碍特点的Dmxl2毛细胞条件性敲除小鼠和p.R1417H突变敲入小鼠，本项目拟通过小鼠模型的毛细胞膜片钳、CAP电位等听觉电生理研究，以及免疫荧光、透射电镜等内耳显微/超微结构病理研究，明确DMXL2在听神经突触病变中的作用和机制，结合毛细胞转录组测序、基因表达调控、蛋白相互作用等在体、离体研究深入探讨相关基因和蛋白的作用通路。本研究有望以DMXL2为切入点在分子层面上更深入的理解听神经突触的作用机制和病变机制，促进相关聋病的诊治与预防。

Our research group has recently identified a novel deafness gene DMXL2 by linkage analysis and exome sequencing of a large deaf family. The p.R1417H mutation of DMXL2 may lead to autosomal dominant hearing loss. The inner ear function and the pathogenic mechanism of DMXL2, however, remains unclear. In our previous studies, we observed that patients with the DMXL2 mutation had the hidden hearing loss phenotype similar to that of auditory synaptopathy. In addition, immunofluorescence analysis showed that Dmxl2 is strongly expressed in the synapse-active region of the mouse inner ear including the basal region of the inner hair cells. Those evidence suggested that DMXL2 may play an important role in the function of the auditory synapses. In this study, we propose to study the function of DMXL2 utilizing the Dmxl2 conditional knock-out mouse and the p.R1417H knock-in mouse models that were previously generated by our group and exhibited similar hearing phenotype as humans. By auditory physiology and inner ear pathology studies of the mouse models, we aim to elucidate whether mutations in DMXL2 may lead to auditory synaptopathy. By molecular biology studies including RNAseq, exogenous gene regulation and co-immunoprecipitation, we seek to explore the interaction and coordination of DMXL2 and other genes in auditory synaptic pathways. The proposed study of DMXL2 may provide important insights into the functional and pathogenic mechanism of auditory synapses and may improve the diagnosis, intervention and prevention of the associated hearing impairment.