Tekt2通过维持斑马鱼毛细胞正常动纤毛形态调控毛细胞发育与功能

文献信息

中文摘要

背景： 感觉毛细胞（HCs）依赖高度极化的顶端装置来检测机械刺激，该装置由富含肌动蛋白的静纤毛和基于微管的动纤毛组成。尽管tektin是保守的微管相关蛋白，富集于纤毛和鞭毛中，但其在感觉毛细胞形态发生和功能中的作用仍知之甚少。
方法： 我们利用单细胞RNA测序、整体原位杂交、基因功能缺失与挽救分析、行为学检测、扫描电子显微镜和FM染料摄取实验，研究了tektin 2（tekt2）在斑马鱼毛细胞中的表达与功能。
结果： 单细胞RNA测序和整体原位杂交显示，tekt2在神经丘、斑和嵴的毛细胞中高表达。tekt2-mCherry报告基因进一步揭示Tekt2富集于毛细胞顶端及动纤毛内。tekt2缺陷导致听觉和前庭功能障碍，并破坏耳石形成，同时伴有耳部纤毛减少和缩短。在神经丘和嵴中，tekt2缺陷使毛细胞数量减少、毛束缩短，并产生异常动纤毛。这些动纤毛缺陷与静纤毛排列紊乱及毛细胞方向性破坏相关。机械转导也一致受损，表现为FM染料摄取减少，而外源性tekt2可部分恢复该功能。
结论： 总之，我们的研究结果确定Tekt2是一种富集于毛细胞的微管相关因子，是斑马鱼毛细胞正常动纤毛形态、顶端极性、毛束组织和机械转导功能所必需的。

英文摘要

BACKGROUND: Sensory hair cells (HCs) rely on a highly polarized apical apparatus, composed of actin-rich stereocilia and a microtubule-based kinocilium, to detect mechanical stimuli. Although tektins are conserved microtubule-associated proteins enriched in cilia and flagella, their roles in sensory HC morphogenesis and function remain poorly understood.
METHODS: We investigated the expression and function of tektin 2 (tekt2) in zebrafish HCs using single-cell RNA sequencing, whole-mount in situ hybridization, genetic loss-of-function and rescue analyses, behavioral assays, scanning electron microscopy, and FM-dye uptake assays.
RESULTS: Single-cell RNA sequencing and whole-mount in situ hybridization showed that tekt2 is highly expressed in neuromast, macular, and crista HCs. A tekt2-mCherry reporter further revealed enrichment of Tekt2 at the HC apex and within the kinocilium. The tekt2 deficiency caused auditory and vestibular dysfunction and disrupted otolith formation, accompanied by reduced and shortened otic cilia. In neuromasts and cristae, tekt2 deficiency decreased HC number, shortened hair bundles, and produced abnormal kinocilia. These kinocilium defects were associated with disorganized stereocilia and disrupted HC orientation. Mechanotransduction was consistently compromised, as indicated by reduced FM-dye uptake, and could be partially restored by exogenous tekt2.
CONCLUSION: Together, our findings identify Tekt2 as an HC-enriched microtubule-associated factor required for normal kinocilium morphology, apical polarity, hair-bundle organization, and mechanotransduction function in zebrafish HCs.