STAPHYLOCOCCUS-AUREUS ALPHA-TOXIN PERMEABILIZES THE BASOLATERAL MEMBRANE OF A CL(-)-SECRETING EPITHELIUM
STAPHYLOCOCCUS-AUREUS ALPHA-TOXIN PERMEABILIZES THE BASOLATERAL MEMBRANE OF A CL(-)-SECRETING EPITHELIUM
复制标题
DOI：
10.1152/ajplung.1992.263.1.l104
复制
发表时间：
1992-07-01
影响因子：
--
通讯作者：
WELSH, MJ
中科院分区：
文献类型：
--
作者：
OSTEDGAARD, LS;SHASBY, DM;WELSH, MJ
在许多上皮细胞中，顶膜离子通道控制着经上皮电解质运输的速率。研究这些通道在其原生位置——顶膜上的一种方法是消除基底侧膜对离子流动的阻力。然后，顶端通道的打开和关闭可以作为一个跨上皮电流来测量，不受基底外侧膜运输过程的影响。为了开发一种使上皮基底外膜渗透到离子和核苷酸的方法，我们研究了金黄色葡萄球菌α毒素对分泌Cl的T84上皮细胞系的影响。α -毒素对Cl-， 3',5'-环磷酸腺苷（cAMP）和GTP具有基底外侧透性，而不是顶端透性。然而，信号转导通路的完整性、根尖膜Cl-通道的调控以及经上皮细胞的抗性保持不变。在检测ATP作用的过程中，我们发现基底外侧膜含有嘌呤能受体，它们既能刺激自身的Cl-分泌，又能在高浓度下抑制camp诱导的Cl-分泌。细胞外ATP的这些作用在长时间暴露于ATP后被消除，提示受体下调。此外，渗透后细胞内ATP的耗竭阻碍了camp依赖性的顶端Cl-通道调节。我们认为α -毒素可能是研究根尖膜离子通道调控和性质的有用工具。
Apical membrane ion channels control the rate of transepithelial electrolyte transport in many epithelia. One way to study such channels in their native location, the apical membrane, is to eliminate the resistance of the basolateral membrane to ion flow. Then the opening and closing of apical channels can be measured as a transepithelial current, free from the influence of basolateral membrane transport processes. To develop a method that would permeabilize an epithelial basolateral membrane to ions and nucleotides, we examined the effect of Staphylococcus aureus alpha-toxin on the Cl--secreting T84 epithelial cell line. Alpha-toxin permeabilized the basolateral, but not the apical, membrane to Cl-, adenosine 3',5'-cyclic monophosphate (cAMP), and GTP. However, the integrity of signal-transduction pathways, the regulation of apical membrane Cl- channels, and the transepithelial resistance remained intact. In the course of examining the effect of ATP, we found that the basolateral membrane contained purinergic receptors that both stimulated Cl- secretion on their own and, at high concentrations, inhibited cAMP-induced Cl- secretion. These effects of extracellular ATP were eliminated after prolonged exposure to ATP, suggesting receptor downregulation. In addition, depletion of intracellular ATP following permeabilization prevented cAMP-dependent regulation of apical Cl- channels. We conclude that alpha-toxin may prove to be a useful tool for studying the regulation and properties of apical membrane ion channels.