State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.
ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.
Cell Mol Life Sci. 2023 May 13;80(6):148. doi: 10.1007/s00018-023-04794-9.
Mutations in GJB2 (Gap junction protein beta 2) are the most common genetic cause of non-syndromic hereditary deafness in humans, especially the 35delG and 235delC mutations. Owing to the homozygous lethality of Gjb2 mutations in mice, there are currently no perfect mouse models carrying Gjb2 mutations derived from patients for mimicking human hereditary deafness and for unveiling the pathogenesis of the disease. Here, we successfully constructed heterozygous Gjb2 and Gjb2 mutant mice through advanced androgenic haploid embryonic stem cell (AG-haESC)-mediated semi-cloning technology, and these mice showed normal hearing at postnatal day (P) 28. A homozygous mutant mouse model, Gjb2, was then generated using enhanced tetraploid embryo complementation, demonstrating that GJB2 plays an indispensable role in mouse placenta development. These mice exhibited profound hearing loss similar to human patients at P14, i.e., soon after the onset of hearing. Mechanistic analyses showed that Gjb2 35delG disrupts the function and formation of intercellular gap junction channels of the cochlea rather than affecting the survival and function of hair cells. Collectively, our study provides ideal mouse models for understanding the pathogenic mechanism of DFNB1A-related hereditary deafness and opens up a new avenue for investigating the treatment of this disease.
GJB2（间隙连接蛋白β 2）基因突变是人类非综合征性遗传性耳聋最常见的遗传原因，尤其是 35delG 和 235delC 突变。由于 Gjb2 基因突变在小鼠中具有纯合致死性，目前尚无携带源自患者的 Gjb2 基因突变的完美小鼠模型来模拟人类遗传性耳聋并揭示疾病的发病机制。在这里，我们成功地通过先进的雄激素单倍体胚胎干细胞（AG-haESC）介导的半克隆技术构建了杂合 Gjb2 和 Gjb2 突变小鼠，这些小鼠在出生后第 28 天（P）表现出正常听力。然后使用增强的四倍体胚胎互补技术生成了纯合突变小鼠模型 Gjb2，表明 GJB2 在小鼠胎盘发育中起着不可或缺的作用。这些小鼠在 P14 时表现出与人类患者相似的严重听力损失，即在听力开始后不久。机制分析表明，Gjb2 35delG 破坏了耳蜗细胞间缝隙连接通道的功能和形成，而不是影响毛细胞的存活和功能。总之，我们的研究为理解 DFNB1A 相关遗传性耳聋的致病机制提供了理想的小鼠模型，并为该疾病的治疗开辟了新途径。
