Department of ENT Institute and Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology, NHC Key Laboratory of Hearing Medicine Research, Fudan University, Shanghai, P. R. China.
Institutes of Biomedical Sciences, Fudan University, Shanghai, P. R. China.
J Comp Neurol. 2023 Oct;531(14):1443-1458. doi: 10.1002/cne.25524. Epub 2023 Jul 18.
The inner ear of mammals includes the cochlea and vestibule, which house specialized hair cells that are responsible for hearing and balance, respectively. While cochlear hair cells fail to regenerate following damage, those of the utricle, which is part of the vestibular apparatus, show partial regeneration. In birds, the macula lagena, a unique ear structure in this clade, has the ability to regenerate hair cells similarly to the utricle. Many studies have sought to explain regeneration in terms of evolution and species differences. However, it remains unclear what the cellular and molecular basis is behind the differences in inner ear structures and between avians and mammals. In the present study, we first investigated the anatomical structures of the inner ear of both chickens and rodents. We then performed RNA sequencing (RNA-Seq) and made cross-species analyses of the expression of homologous genes obtained from the inner ear tissue from both chickens and mice. Finally, we focused on the lagena, the basilar papilla, and the utricle in chickens and identified differentially expressed genes between tissues and determined the expression patterns of genes involved in inner ear structure formation by single-cell RNA sequencing and bulk RNA-Seq. We concluded that the cellular and molecular composition of the lagena is more similar to that of the utricle than the cochlea. Taken together, our study provides a valuable resource for the study of inner ear evolution and development.
哺乳动物的内耳包括耳蜗和前庭，其中分别容纳了专门的毛细胞，这些毛细胞分别负责听觉和平衡。虽然耳蜗毛细胞在受损后无法再生，但前庭器官的一部分——椭圆囊的毛细胞则显示出部分再生能力。在鸟类中，独特的耳结构——瓶状囊斑具有类似于椭圆囊的毛细胞再生能力。许多研究试图从进化和物种差异的角度来解释再生现象。然而，内耳结构的差异以及鸟类和哺乳动物之间的差异的细胞和分子基础仍不清楚。在本研究中，我们首先研究了鸡和啮齿动物内耳的解剖结构。然后，我们对从鸡和鼠的内耳组织中获得的同源基因进行了 RNA 测序（RNA-Seq）和种间分析。最后，我们重点研究了鸡的瓶状囊斑、基底乳头和椭圆囊，鉴定了组织间差异表达基因，并通过单细胞 RNA 测序和批量 RNA-Seq 确定了参与内耳结构形成的基因表达模式。我们得出的结论是，瓶状囊斑的细胞和分子组成与椭圆囊更相似，而与耳蜗不同。综上所述，我们的研究为内耳进化和发育的研究提供了有价值的资源。
