Striatin, a subunit of the serine/threonine phosphatase PP2A, is a core member of the conserved striatin-interacting phosphatase and kinase (STRIPAK) complexes. The protein is expressed in the cell junctions between epithelial cells, which play a role in maintaining cell–cell adhesion. Since the cell junctions are crucial for the function of the mammalian inner ear, we examined the localization and function of striatin in the mouse cochlea. Our results show that in neonatal mice, striatin is specifically expressed in the cell–cell junctions of the inner hair cells, the receptor cells in the mammalian cochlea. Auditory brainstem response measurements of striatin-deficient mice indicated a progressive, high-frequency hearing loss, suggesting that striatin is essential for normal hearing. Moreover, scanning electron micrographs of the organ of Corti revealed a moderate degeneration of the outer hair cells in the middle and basal regions, concordant with the high-frequency hearing loss. Additionally, striatin-deficient mice show aberrant ribbon synapse maturation. Loss of the outer hair cells, combined with the aberrant ribbon synapse distribution, may lead to the observed auditory impairment. Together, these results suggest a novel function for striatin in the mammalian auditory system.

Striatin 是丝氨酸/苏氨酸磷酸酶 PP2A 的一个亚基，是保守的 striatin 相互作用磷酸酶和激酶 (STRIPAK) 复合物的核心成员。该蛋白在上皮细胞之间的细胞连接处表达，在维持细胞间粘附方面发挥作用。由于细胞连接对于哺乳动物内耳的功能至关重要，因此我们检查了条纹蛋白在小鼠耳蜗中的定位和功能。我们的结果表明，在新生小鼠中，纹状体蛋白在内毛细胞（哺乳动物耳蜗中的受体细胞）的细胞-细胞连接处特异性表达。对striatin缺陷小鼠的听觉脑干反应测量表明其存在进行性高频听力损失，这表明striatin对于正常听力至关重要。此外，柯蒂氏器的扫描电子显微照片显示，中部和基底区域的外毛细胞中度变性，与高频听力损失一致。此外，条纹蛋白缺陷的小鼠表现出异常的带状突触成熟。外毛细胞的丧失，加上异常的带状突触分布，可能会导致观察到的听觉障碍。总之，这些结果表明纹状体在哺乳动物听觉系统中具有新的功能。