The primary cilium, an important microtubule-based organelle, protrudes from nearly all the vertebrate cells. The motility of cilia is necessary for various developmental and physiological processes. Phosphoinositides (PIs) and its metabolite, PtdIns(4,5)P2, have been revealed to contribute to cilia assembly and disassembly. As an important kinase of the PI pathway and signaling, phosphatidylinositol 4-kinase β (PI4KB) is the one of the most extensively studied phosphatidylinositol 4-kinase isoform. However, its potential roles in organ development remain to be characterized. To investigate the developmental role of Pi4kb, especially its function on zebrafish ciliogenesis, we generated pi4kb deletion mutants using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 technique. The homozygous pi4kb mutants exhibit an absence of primary cilia in the inner ear, neuromasts, and pronephric ducts accompanied by severe edema in the eyes and other organs. Moreover, smaller otic vesicle, malformed semicircular canals, and the insensitivity on sound stimulation were characteristics of pi4kb mutants. At the protein level, both in vivo and in vitro analyses revealed that synthesis of Pi4p was greatly reduced owing to the loss of Pi4kb. In addition, the expression of the Pi4kb-binding partner of neuronal calcium sensor-1, as well as the phosphorylation of phosphatidylinositol-4-phosphate downstream effecter of Akt, was significantly inhibited in pi4kb mutants. Taken together, our work uncovers a novel role of Pi4kb in zebrafish inner ear development and the functional formation of hearing ability by determining hair cell ciliogenesis.

初级纤毛是一种重要的基于微管的细胞器，几乎从所有脊椎动物细胞中伸出。纤毛的运动是各种发育和生理过程所必需的。已发现磷酸肌醇 (PI) 及其代谢物 PtdIns(4,5)P2 有助于纤毛组装和拆卸。作为 PI 通路和信号传导的重要激酶，磷脂酰肌醇 4-激酶 β (PI4KB) 是研究最广泛的磷脂酰肌醇 4-激酶异构体之一。然而，其在器官发育中的潜在作用仍有待表征。为了研究 Pi4kb 的发育作用，尤其是它对斑马鱼纤毛发生的作用，我们生成了pi4kb使用成簇规则间隔短回文重复序列 (CRISPR)/CRISPR 相关蛋白 9 技术的缺失突变体。纯合pi4kb突变体在内耳、神经瘤和前肾管中没有初级纤毛，并伴有眼睛和其他器官的严重水肿。此外，较小的耳泡、畸形的半规管和对声音刺激的不敏感是pi4kb突变体的特征。在蛋白质水平，体内和体外分析表明，由于 Pi4kb 的丢失，Pi4p 的合成大大减少。此外，在pi4kb突变体中，神经元钙传感器 1 的 Pi4kb 结合伴侣的表达以及 Akt 下游效应物 4-磷酸磷脂酰肌醇的磷酸化受到显着抑制。总之，我们的工作通过确定毛细胞纤毛发生揭示了 Pi4kb 在斑马鱼内耳发育和听力功能形成中的新作用。