The prestin-based active process in the mammalian outer hair cells (OHCs) is believed to play a crucial role in auditory signal amplification in the cochlea. Prestin belongs to an anion transporter family (SLC26A). It is densely expressed in the OHC lateral plasma membrane and functions as a voltage-dependent motor protein. Analog genes can be found in the genome of nonmammalian species, but their functions in hearing are poorly understood. In the present study, we used the gerbil prestin sequence as a template and identified an analog gene in the bullfrog genome. We expressed the gene in a stable cell line (HEK293T) and performed patch-clamp recording. We found that these cells exhibited prominent nonlinear capacitance (NLC), a widely accepted assay for prestin functioning as a motor protein. Upon close examination, the key parameters of this NLC are comparable to that conferred by the gerbil prestin, and nontransfected cells failed to display NLC. Lastly, we performed patch-clamp recording in HCs of all three hearing organs in bullfrog. HCs in both the sacculus and the amphibian papilla exhibited a capacitance profile that is similar to NLC while HCs in the basilar papilla showed no sign of NLC. Whether or not this NLC-like capacitance change is involved in auditory signal amplification certainly requires further examination; our results represent the first and necessary step in revealing possible roles of prestin in the active hearing processes found in many nonmammalian species.

中文翻译：

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牛蛙听力器官中的Prestin模拟基因的体外研究。

哺乳动物外毛细胞（OHCs）中基于prestin的活性过程被认为在耳蜗的听觉信号放大中起关键作用。Prestin属于阴离子转运蛋白家族（SLC26A）。它在OHC侧质膜中密集表达，并起电压依赖性运动蛋白的作用。可以在非哺乳动物物种的基因组中找到模拟基因，但对它们在听力中的功能了解甚少。在本研究中，我们使用沙鼠的prestin序列作为模板，并在牛蛙基因组中鉴定了一个类似基因。我们在稳定的细胞系（HEK293T）中表达了该基因，并进行了膜片钳记录。我们发现，这些细胞表现出突出的非线性电容（NLC），这是一种广为接受的针对Prestin发挥运动蛋白功能的检测方法。经过仔细检查 该NLC的关键参数可与沙鼠Prestin所提供的参数相媲美，并且未转染的细胞无法显示NLC。最后，我们在牛蛙中所有三个听力器官的HC中进行了膜片钳记录。囊和两栖乳头中的HC均显示出与NLC相似的电容分布，而基底乳头中的HC未显示出NLC的迹象。当然，这种类似于NLC的电容变化是否与听觉信号放大有关。我们的结果代表了揭示Prestin在许多非哺乳动物物种的活跃听力过程中可能发挥作用的第一步和必要步骤。我们在牛蛙中所有三个听力器官的HC中进行了膜片钳记录。囊和两栖乳头中的HC均显示出与NLC相似的电容分布，而基底乳头中的HC未显示出NLC的迹象。当然，这种类似于NLC的电容变化是否与听觉信号放大有关。我们的结果代表了揭示Prestin在许多非哺乳动物物种发现的主动听力过程中可能发挥作用的第一步和必要步骤。我们在牛蛙中所有三个听力器官的HC中进行了膜片钳记录。囊和两栖乳头中的HC均显示出与NLC相似的电容分布，而基底乳头中的HC未显示出NLC的迹象。当然，这种类似于NLC的电容变化是否与听觉信号放大有关。我们的结果代表了揭示Prestin在许多非哺乳动物物种的活跃听力过程中可能发挥作用的第一步和必要步骤。