Njeshi Charity Nya, Choudhary Shivani, McHugh Mark Andrew, Kashyap Sudhanva Srinivas, Robertson Alan Patrick, Martin Richard John
Iowa State University.
Res Sq. 2025 Aug 4:rs.3.rs-7206784. doi: 10.21203/rs.3.rs-7206784/v1.
Control of onchocerciasis (river blindness of humans due to infection with the filarial nematode, ) remains a challenge because of the lack of effective adulticides and vaccines. Emodepside is a broad-spectrum veterinary anthelmintic that has been found to inhibit nematode muscle activity by activating their tetrameric SLO-1K channels. Emodepside has adulticidal activity and is being trialed for onchocerciasis treatment, but the molecular mode of action of emodepside is still being elucidated. Here we examine the single-channel currents of -SLO-1A, a SLO-1K splice variant from , and explore how emodepside modulates the dynamics of the opening of the channel.
-SLO-1A was expressed in HEK 293 cells, and patch clamp electrophysiology techniques were used to record currents. Single-channel currents were recorded in a symmetrical 132 mM K solution to determine the main open-state channel conductance. Emodepside's effects were tested at 0.3 μM and 1.0 μM.
-SLO-1A had a main open-state conductance of 110 ± 3 pS and frequent flickering sub-conductance states. The presence of the flickering sub-conductance states suggests that there is limited cooperativity between the tetrameric channel subunits required for opening to the main open-state. Emodepside increased mean current amplitudes. Emodepside also increased open-burst times, and open probability. Verruculogen (1 μM) inhibited channel opening in the presence or absence of emodepside.
This study successfully expressed -SLO-1A in HEK 293 cells, measured the conductance of the main open-state and detected the presence of sub-conductance states, and flickering openings. The increased amplitudes of the single-channel currents, open-burst times and open probabilities provide insights into how emodepside increases Slo-1K currents and illustrate dynamic actions of emodepside on -SLO-1A.
由于缺乏有效的成虫杀虫剂和疫苗，盘尾丝虫病（由丝虫线虫感染导致的人类河盲症）的控制仍然是一项挑战。埃玛菌素是一种广谱兽用驱虫药，已发现它可通过激活四聚体SLO-1K通道来抑制线虫肌肉活动。埃玛菌素有杀成虫活性，正在进行盘尾丝虫病治疗试验，但其分子作用模式仍在阐明之中。在此，我们研究了来自[具体物种]的SLO-1K剪接变体-SLO-1A的单通道电流，并探讨埃玛菌素如何调节通道开放的动力学。
-SLO-1A在HEK 293细胞中表达，采用膜片钳电生理技术记录电流。在对称的132 mM K溶液中记录单通道电流，以确定主要开放状态的通道电导。在0.3 μM和1.0 μM浓度下测试埃玛菌素的作用。
-SLO-1A的主要开放状态电导为110±3 pS，且存在频繁闪烁的亚电导状态。闪烁亚电导状态的存在表明，向主要开放状态开放所需的四聚体通道亚基之间的协同作用有限。埃玛菌素增加了平均电流幅度。埃玛菌素还增加了开放爆发时间和开放概率。疣孢菌素（1 μM）在有或没有埃玛菌素存在的情况下均抑制通道开放。
本研究成功在HEK 293细胞中表达了-SLO-1A，测量了主要开放状态的电导，并检测到亚电导状态和闪烁开放的存在。单通道电流幅度、开放爆发时间和开放概率的增加，为埃玛菌素如何增加Slo-1K电流提供了见解，并说明了埃玛菌素对-SLO-1A的动态作用。
