新的聋病相关基因Math6在小鼠中致聋机制研究及人类同源基因突变与聋病的相关性分析

Identification of any new deafness gene is highly valuable for deafness gene screening. Math6 (Atoh8), a bHLH transcription factor, shows high homology between human and mouse. While, it's reported Math6 mutant embryos will die before birth by traditional knock-out methods thus makes it impossible to study the function of Math6 at later stages and in adult. Interestingly, Math6 mutant mice we constructed by intercrossing of Math6LacZ-KI/+ mice are viable but severely deafened, which suggests Math6 is a novel deafness-related gene. We also found there are many similarly severely deafened patients with unknown reasons.With informed consent, we collected their blood samples for deafness gene screening. If no mutations detected for routine gene screening, deep sequencing would be performed. Among them, in two patients there are mutations detected on MATH6 gene by deep sequencing,although we are not sure these mutations are functional or not. Thus, we hypothesize here that: Math6 mutation will result in severe deafness in an auto-recessive way; dysfunction of cochlear outer hair cells may be responsible for the deafness; Math6 is essential for the development / maintenance of normal hearing. We plan to further study the hereditary way, the morphology and structural changes of cochlea, functions of cochlear hair cells and supporting cells, the temporal and space expression pattern and the regulatory network of Math6. And we will also keep on expanding our deaf patients sample bank and focusing on the results of Math6 sequencing and regulatory network combined with bioinformatics techniques. We hope to elucidate the functions of Math6 on hearing and deafness, establish a platform for study and treatment from mouse to human and construct the screening technique for detecting Math6 mutation in human. It seems we are the first team declared that targeted deletion of Math6 will result in severe deafness in mice. By now,there are no matched articles about Math6 and deafness founded yet on Pubmed, Wanfang or GoogleScholar, which suggests our study is original and it's highly worthy for further study.

bHLH转录因子Math6（Atoh8）在小鼠与人类中高度同源。我们采用Math6LacZ-KI技术获得可以存活并传代的纯合突变小鼠，并经检测首次发现其为重度耳聋，提示Math6为新的聋病相关基因。另外我们经测序发现两例重度耳聋病人MATH6存在突变。根据预实验资料，我们提出如下假说： Math6为常隐遗传，在听觉发育与功能维持中作用重要，其突变引起耳蜗外毛细胞结构或功能缺陷，导致重度耳聋；人类同源基因突变可能导致类似病变。本项目拟进一步验证小鼠Math6遗传方式、致聋机制；结合生物信息学分析，阐明Math6上下游调控机制；结合临床重度耳聋病人MATH6基因序列分析资料，重点研究病人MATH6突变导致耳聋的可能性及致病机制；构建临床MATH6突变检测技术。经检索，目前尚无任何有关Math6与耳聋相关性文献报道，本研究为原创，亟待深入。

尽早发现聋病基因、明确致聋原因并进行积极干预，可以有效减少听觉残疾发生、降低出生缺陷比例，并极大地缓解家庭和社会的经济与伦理负担。在前期研究中，我们在小鼠中新发现bHLH转录因子Math6 基因突变可以导致重度耳聋，本研究以此为切入点，深入研究Math6 在听觉发育与维持中的功能、调控网络及其作用，并研究人类中同源基因突变与人类耳聋的相关性及致病机制，明确在人类中Math6 是否为新的聋病基因，促进遗传性聋病的诊断和防治工作发展。我们提出并验证了以下科学假说：“Math6 突变导致小鼠遗传性重度耳聋，遗传方式为常染色体隐性遗传, 耳蜗Corti 氏器外毛细胞或相邻细胞结构/功能的缺陷是导致重度耳聋的可能原因; 在人类同源基因MATH6 突变亦可能导致重度耳聋。”本课题以Math6 突变小鼠耳聋动物模型为研究对象，我们通过研究并证实，Math6在小鼠中导致遗传性聋为常染色体隐性遗传方式；在人类中同源基因MATH6突变与部分遗传性聋密切相关。我们研究和明确了Math6 在小鼠耳蜗的表达方式和主要功能，研究发现： Math6纯合突变可导致小鼠重度耳聋，身长和体重显著低于同窝对照小鼠；内耳结构未发现明显缺陷，耳蜗内毛细胞和外毛细胞形态和数目未见明显异常，毛细胞主要功能蛋白表达未见明显差异，外毛细胞特征性功能蛋白Prestin表达正常，但透射电镜提示在纯合突变小鼠中内耳外毛细胞与周围支持细胞间紧密连接疏松，提示细胞间紧密连接和稳固性改变可能与听觉功能严重受损有关。通过研究Math6和Neurogenin3等相关基因的上下游关系以及非编码RNA等调控机制，初步绘制了调控网络。利用小鼠动物模型研究结果和病人聋病基因检测结果，初步确定Math6为新的聋病相关基因，对完善临床遗传性聋病检测技术和干预策略提供了有力帮助。在课题实施过程中，建立和培养了遗传性聋病研究队伍，已发表高水平SCI论文2篇、已接收待发表SCI论文1篇、投稿审稿中SCI论文1篇。本课题已基本按照研究计划书原研究目标和内容执行和完成，取得了比较理想的成果。