Osman Sangar, Taylor Kirk A, Allcock Natalie, Rainbow Richard D, Mahaut-Smith Martyn P
Department of Molecular and Cell Biology, University of Leicester, Leicester, UK, LE1 9HN.
Centre for Core Biotechnology Services, University of Leicester, Leicester, UK, LE1 9HN.
Sci Rep. 2016 Jan 4;6:18536. doi: 10.1038/srep18536.
Several cell types develop extensive plasma membrane invaginations to serve a specific physiological function. For example, the megakaryocyte demarcation membrane system (DMS) provides a membrane reserve for platelet production and muscle transverse (T) tubules facilitate excitation:contraction coupling. Using impermeant fluorescent indicators, capacitance measurements and electron microscopy, we show that multiple cationic amphiphilic drugs (CADs) cause complete separation of the DMS from the surface membrane in rat megakaryocytes. This includes the calmodulin inhibitor W-7, the phospholipase-C inhibitor U73122, and anti-psychotic phenothiazines. CADs also caused loss of T tubules in rat cardiac ventricular myocytes and the open canalicular system of human platelets. Anionic amphiphiles, U73343 (a less electrophilic U73122 analogue) and a range of kinase inhibitors were without effect on the DMS. CADs are known to accumulate in the inner leaflet of the cell membrane where they bind to anionic lipids, especially PI(4,5)P2. We therefore propose that surface detachment of membrane invaginations results from an ability of CADs to interfere with PI(4,5)P2 interactions with cytoskeletal or BAR domain proteins. This establishes a detubulating action of a large class of pharmaceutical compounds.
几种细胞类型会形成广泛的质膜内陷以发挥特定的生理功能。例如，巨核细胞分界膜系统（DMS）为血小板生成提供膜储备，而肌肉横管（T管）则促进兴奋 - 收缩偶联。通过使用非渗透性荧光指示剂、电容测量和电子显微镜，我们发现多种阳离子两亲性药物（CADs）会导致大鼠巨核细胞中的DMS与表面膜完全分离。这包括钙调蛋白抑制剂W - 7、磷脂酶C抑制剂U73122和抗精神病药物吩噻嗪。CADs还会导致大鼠心室肌细胞中的T管和人类血小板的开放小管系统消失。阴离子两亲物、U73343（一种亲电性较弱的U73122类似物）和一系列激酶抑制剂对DMS没有影响。已知CADs会积聚在细胞膜的内小叶中，在那里它们与阴离子脂质结合，尤其是磷脂酰肌醇 - 4,5 - 二磷酸（PI(4,5)P2）。因此，我们提出膜内陷的表面脱离是由于CADs干扰PI(4,5)P2与细胞骨架或BAR结构域蛋白相互作用的能力所致。这确立了一大类药物化合物的去管化作用。
