Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, Warsaw, Poland; Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland.
Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, Warsaw, Poland; Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland.
Mitochondrion. 2022 Jul;65:23-32. doi: 10.1016/j.mito.2022.04.005. Epub 2022 Apr 30.
Large-conductance calcium-regulated potassium channel (BK) is known to play an important role in physiological and pathological processes. Despite the BK channel being encoded by one gene, this channel has been found to be located not only in the cell membrane but also in the membranes of intracellular compartments, such as in the inner mitochondrial membrane. With some differences, the mitochondrial BK (mitoBK) channel has been shown to be activated or inhibited by both synthetic and natural compounds. One of them, paxilline, has been considered to be a canonical blocker of this channel. In the previous study, we showed that the natural origin substance quercetin activates the mitoBK channel at ten times lower the concentration compared to channel present in the plasma membrane. Here, using the patch-clamp technique, we report that after inhibition of mitoBK channels by paxilline, quercetin activates these channels, indicating a paxilline and quercetin binding competition in the regulation of the mitoBK channel. To support our hypothesis, we used an analog of quercetin - isorhamnetin, a substance with one substituent changed. Isorhamnetin has no effect on the mitoBK channel activity, and after its application, paxilline fully inhibits the channel. Additionally, the molecular modeling studies were used. The results of docking quercetin and paxilline to the BK channel suggest that paxilline cannot bind after activation of the channel with quercetin. It seems that the likely mechanism of this phenomenon is the formation of spatial hindrance by quercetin. The results obtained shed a completely new, groundbreaking in the paxilline context, light on the current knowledge about mitochondrial potassium channel regulation.
大电导钙激活钾通道（BK）在生理和病理过程中起着重要作用。尽管 BK 通道仅由一个基因编码，但已发现该通道不仅位于细胞膜上，而且还位于细胞内隔室的膜上，例如在内线粒体膜上。尽管存在一些差异，但已经表明线粒体 BK（mitoBK）通道可被合成和天然化合物激活或抑制。其中一种，紫杉酚，已被认为是该通道的典型抑制剂。在以前的研究中，我们表明与质膜中存在的通道相比，天然来源物质槲皮素以低十倍的浓度激活 mitoBK 通道。在这里，我们使用膜片钳技术报告，在用紫杉酚抑制 mitoBK 通道后，槲皮素激活了这些通道，这表明紫杉酚和槲皮素在调节 mitoBK 通道方面存在竞争结合。为了支持我们的假设，我们使用了槲皮素的类似物异鼠李素，一种取代基发生变化的物质。异鼠李素对 mitoBK 通道活性没有影响，并且在用其处理后，紫杉酚完全抑制了通道。此外，还使用了分子建模研究。将槲皮素和紫杉酚对接至 BK 通道的结果表明，通道被槲皮素激活后，紫杉酚无法结合。似乎这种现象的可能机制是槲皮素形成空间障碍。获得的结果为当前关于线粒体钾通道调节的知识提供了全新的、突破性的认识。
