Abstract：
AbstractIntegrated chemo- and mechanosensory pathways, along with activated calcium influxes, regulate nematocyst discharge from sea anemone tentacles. Discharge from vibration-sensitive Type A cnidocyte supporting cell complexes use calcium-conducting transient receptor potential V4-like channels. Because calcium influxes often couple with calcium-activated, large-conductance potassium (BK) channels, we hypothesized that BK channels function in nematocyst discharge. To verify this hypothesis, we first tested five selective BK channel blockers on nematocyst-mediated prey killing in Diadumene lineata (aka Haliplanella luciae). All tested BK channel blockers inhibited prey killing at concentrations comparable to their inhibition of vertebrate BK channels. In addition, the BK channel blocker paxilline selectively inhibited prey killing mediated by vibration-sensitive Type A cnidocyte supporting cell complexes. We queried a mammalian BKα amino acid sequence to the Exaiptasia diaphena database, from which we identified a putative anemone, pore-forming BKα subunit sequence. Using the E. diaphena BKα sequence as a template, we assembled a BKα transcript from our assembled D. lineata transcriptome. In addition, the hydra homolog of D. lineata BKα localizes to nematocytes on the hydra single-cell RNA sequencing map. Our findings suggest that D. lineata expresses BK channels that play a role in vibration-sensitive nematocyst discharge from Type A cnidocyte supporting cell complexes. We believe this is the first functional demonstration of BK channels in nonbilaterians. Because stimulated chemoreceptors frequency tune Type A cnidocyte supporting cell complexes to frequencies matching swimming movements of prey via a protein kinase A signaling pathway and protein kinase A generally activates BK channels, we suggest that D. lineata BK channels may participate in protein kinase A-mediated frequency tuning.
摘要：
综合化学和机械感觉途径，随着激活的钙流入，调节海葵触须的线囊排出。从振动敏感的A型细胞支持细胞复合物中放电使用钙传导的瞬时受体电位V4样通道。因为钙流入通常与钙激活结合，大电导钾（BK）通道，我们假设BK通道在线虫囊排出中起作用。为了验证这个假设，我们首先测试了五种选择性BK通道阻断剂在Diadumenelineata（akaHaliplanellaluciae）中对线虫囊介导的猎物杀死作用。所有测试的BK通道阻断剂在与它们对脊椎动物BK通道的抑制作用相当的浓度下都抑制了猎物的杀伤。此外,BK通道阻断剂Paxillinine选择性地抑制了由振动敏感的A型细胞支持细胞复合物介导的猎物杀伤。我们将哺乳动物BKα氨基酸序列查询到Exaiptasiadiaphena数据库，我们从中确定了一个推定的海葵，成孔BKα亚基序列。使用E.diaphenaBKα序列作为模板，我们从组装的D.lineata转录组中组装了一个BKα转录本。此外,D.lineataBKα的hyda同源物定位于hyda单细胞RNA测序图谱上的线虫细胞。我们的发现表明，D.lineata表达BK通道，这些通道在A型刺细胞支持细胞复合物的振动敏感性线虫囊排出中起作用。我们认为这是非双边BK通道的第一个功能演示。因为受刺激的化学感受器频率调节A型CNidcell支持细胞复合物的频率，以通过蛋白激酶A信号通路和蛋白激酶A激活BK通道来匹配猎物的游泳运动，我们认为，D.lineataBK通道可能参与蛋白激酶A介导的频率调谐。
