This is the first work to use a newly designed Li+-selective photoswitchable probe Sabrina Heng Lithium (SHL) in living colon cancer cells to noninvasively monitor cation channel activity in real time by the appearance of lithium hot spots detected by confocal microscopy. Punctate Li+ hot spots are clustered in the lamellipodial leading edges of HT29 human colon cancer cells and are colocalized with aquaporin-1 (AQP1) channels. AQP1 is a dual water and cyclic-nucleotide-gated cation channel located in lamellipodia and is essential for rapid cell migration in a subset of aggressive cancers. Both the Li+ hot spots and cell migration are blocked in HT29 cells by the AQP1 ion channel antagonist AqB011. In contrast, Li+ hot spots are not evident in a poorly migrating colon cancer cell line, SW620, which lacks comparable membrane expression of AQP1. Knockdown of AQP1 by RNA interference in HT29 cells significantly impairs Li+ hot spot activity. The SHL probe loaded in living cells shows signature chemical properties of ionic selectivity and reversibility. Dynamic properties of the Li+ hot spots, turning on and off, are confirmed by time-lapse imaging. SHL is a powerful tool for evaluating cation channel function in living cells in real time, with particular promise for studies of motile cells or interlinked networks not easily analyzed by electrophysiological methods. The ability to reset SHL by photoswitching allows monitoring of dynamic signals over time. Future applications of the Li+ probe could include high-throughput optical screening for discovering new classes of channels, or finding new pharmacological modulators for nonselective cation channels.
这是第一项在活体结肠癌细胞中使用新设计的
锂+选择性光开关探针Sabrina Heng Lithium(SHL)的研究,通过共聚焦显微镜检测
锂热点的出现,无创实时监测阳离子通道活性。点状
锂热点聚集在 HT29 人结肠癌细胞的薄壁前缘,并与
水通道蛋白-1(AQP1)通道共聚焦。AQP1 是一种双
重水和环状核苷酸门控阳离子通道,位于薄壁小体中,对一部分侵袭性癌症细胞的快速迁移至关重要。AQP1 离子通道拮抗剂 AqB011 可阻断 HT29 细胞中的 Li+ 热点和细胞迁移。相反,在迁移能力差的结肠癌
细胞系 SW620 中,Li+ 热点并不明显,因为 SW620 缺乏类似的 AQP1 膜表达。在 HT29 细胞中通过 RNA 干扰敲除 AQP1 能显著削弱 Li+ 热点的活性。装载在活细胞中的 SHL 探针显示出离子选择性和可逆性的标志性
化学特性。延时成像证实了 Li+ 热点开启和关闭的动态特性。SHL 是实时评估活细胞中阳离子通道功能的强大工具,尤其适合研究电生理方法不易分析的运动细胞或相互关联的网络。通过光开关重置 SHL 的能力可以监测一段时间内的动态信号。Li+ 探针的未来应用可能包括发现新通道类别的高通量光学筛选,或为非选择性阳离子通道寻找新的药理调节剂。