HCN channels are essential for the escape response of Paramecium.

IF 2.1 4区 生物学 Q3 MICROBIOLOGY
Daisuke Kandabashi, Mutsumi Kawano, Shinobu Izutani, Hiyori Harada, Takashi Tominaga, Manabu Hori
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引用次数: 0

Abstract

When mechanical stimulation was applied to free swimming Paramecium, forward swimming velocity transiently increased due to activation of the posterior mechanosensory channels. The behavior response, known as "escape response," requires membrane hyperpolarization and the activation of K-channel type adenylate cyclases. Our hypothesis is that this escape response also involves activation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. HCN channels are activated by hyperpolarization and are modulated by cyclic nucleotides such as cAMP and cGMP. They play a critical role in many excitable cells in higher animals. If HCN channels act in Paramecium, this should help to enhance and prolong hyperpolarization, thereby increasing the swimming speed of Paramecium. This study used RNAi to examine the role of the HCN channel 1 in the escape responses by generating hcn1-gene knockdown cells (hcn1-KD). These cells showed reduced mechanically-stimulated escape responses and a lack of cGMP-dependent increases in swimming speed. Electrophysiological experiments demonstrated reduced hyperpolarization upon injection of large negative currents in hcn1-KD cells. This is consistent with a decrease in HCN1 channel activity and changes in the escape response. These findings suggest that HCN1 channels are K+ channels that regulate the escape response of Paramecium by amplifying the hyperpolarizations elicited by posterior mechanical stimulation.

HCN通道对鹦鹉螺的逃逸反应至关重要。
当对自由游动的鹦鹉螺施加机械刺激时,由于后部机械感觉通道被激活,向前游动的速度会短暂增加。这种行为反应被称为 "逃逸反应",需要膜超极化和 K 通道型腺苷酸环化酶的激活。我们的假设是,这种逃避反应还涉及激活超极化激活的环核苷酸门控(HCN)通道。HCN 通道通过超极化激活,并受环核苷酸(如 cAMP 和 cGMP)的调节。它们在高等动物的许多兴奋细胞中发挥着关键作用。如果 HCN 通道在副跃类动物中发挥作用,这将有助于增强和延长超极化,从而提高副跃类动物的游泳速度。本研究使用 RNAi 技术,通过产生 hcn1 基因敲除细胞(hcn1-KD)来研究 HCN 通道 1 在逃逸反应中的作用。这些细胞表现出机械刺激的逃逸反应减弱,游速增加缺乏 cGMP 依赖性。电生理实验表明,在注入大负电流时,hcn1-KD 细胞的超极化程度降低。这与 HCN1 通道活性的降低和逃逸反应的变化是一致的。这些研究结果表明,HCN1 通道是一种 K+ 通道,可通过放大后机械刺激引起的超极化来调节鹦鹉螺的逃逸反应。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
4.30
自引率
4.50%
发文量
85
审稿时长
6-12 weeks
期刊介绍: The Journal of Eukaryotic Microbiology publishes original research on protists, including lower algae and fungi. Articles are published covering all aspects of these organisms, including their behavior, biochemistry, cell biology, chemotherapy, development, ecology, evolution, genetics, molecular biology, morphogenetics, parasitology, systematics, and ultrastructure.
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