BACKGROUND During Drosophila oogenesis, the follicular epithelium differentiates into several morphologically distinct follicle-cell populations. Characteristic bioelectrical properties make this tissue a suitable model system for studying connections between electrochemical signals and the organisation of the cytoskeleton. Recently, we have described stage-specific transcellular antero-posterior and dorso-ventral gradients of intracellular pH (pHi) and membrane potential (Vmem) depending on the asymmetrical distribution and/or activity of various ion-transport mechanisms. In the present study, we analysed the patterns of basal microfilaments (bMF) and microtubules (MT) in relation to electrochemical signals. RESULTS The bMF- and MT-patterns in developmental stages 8 to 12 were visualised using labelled phalloidin and an antibody against acetylated α-tubulin as well as follicle-cell specific expression of GFP-actin and GFP-α-tubulin. Obviously, stage-specific changes of the pHi- and Vmem-gradients correlate with modifications of the bMF- and MT-organisation. In order to test whether cytoskeletal modifications depend directly on bioelectrical changes, we used inhibitors of ion-transport mechanisms that have previously been shown to modify pHi and Vmem as well as the respective gradients. We inhibited, in stage 10b, Na+/H+-exchangers and Na+-channels with amiloride, V-ATPases with bafilomycin, ATP-sensitive K+-channels with glibenclamide, voltage-dependent L-type Ca2+-channels with verapamil, Cl--channels with 9-anthroic acid and Na+/K+/2Cl--cotransporters with furosemide, respectively. The correlations between pHi, Vmem, bMF and MT observed in different follicle-cell types are in line with the correlations resulting from the inhibition experiments. While relative alkalisation and/or hyperpolarisation stabilised the parallel transversal alignment of bMF, acidification led to increasing disorder and to condensations of bMF. On the other hand, relative acidification as well as hyperpolarisation stabilised the longitudinal orientation of MT, whereas alkalisation led to loss of this arrangement and to partial disintegration of MT. CONCLUSIONS We conclude that the pHi- and Vmem-changes induced by inhibitors of ion-transport mechanisms simulate bioelectrical changes occurring naturally and leading to the cytoskeletal changes observed during differentiation of the follicle-cell epithelium. Therefore, gradual modifications of electrochemical signals can serve as physiological means to regulate cell and tissue architecture by modifying cytoskeletal patterns.

中文翻译：

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果蝇卵巢上皮形态发生过程中，电化学梯度参与调节细胞骨架模式。

背景技术在果蝇卵子发生期间，滤泡上皮分化为几个形态上不同的滤泡细胞群。生物电特性使该组织成为研究电化学信号与细胞骨架组织之间联系的合适模型系统。最近，我们已经描述了不同的离子转运机制的不对称分布和/或活性，特定阶段的细胞内pH（pHi）和膜电位（Vmem）的跨细胞前后-和后-腹梯度。在本研究中，我们分析了与电化学信号有关的基底微丝（bMF）和微管（MT）的模式。结果使用标记的鬼笔环肽和针对乙酰化的α-微管蛋白的抗体以及GFP-肌动蛋白和GFP-α-微管蛋白的卵泡细胞特异性表达，可以观察到处于发育阶段8至12的bMF和MT模式。显然，pHi和Vmem梯度的阶段特定变化与bMF-和MT组织的修饰相关。为了测试细胞骨架的修饰是否直接取决于生物电的变化，我们使用了离子转运机制的抑制剂，该抑制剂先前已被证明可以改变pHi和Vmem以及相应的梯度。在10b期，我们用阿米洛利抑制Na + / H +交换子和Na +通道，用巴氟霉素抑制V-ATPase，用格列本脲抑制ATP敏感的K +通道，用维拉帕米抑制电压依赖性L型Ca2 +通道，Cl-通道分别与9-邻氨基甲酸和Na + / K + / 2Cl-共同转运与速尿。在不同的卵泡细胞类型中观察到的pHi，Vmem，bMF和MT之间的相关性与抑制实验产生的相关性一致。尽管相对碱化和/或超极化稳定了bMF的平行横向排列，但酸化却导致bMF的紊乱增加和缩合。另一方面，相对酸化以及超极化作用稳定了MT的纵向取向，而碱化则导致该排列的损失和MT的部分崩解。结论我们得出的结论是，离子转运机制抑制剂诱导的pHi和Vmem变化模拟了自然发生的生物电变化，并导致在卵泡细胞上皮细胞分化过程中观察到的细胞骨架变化。因此，电化学信号的逐渐修饰可以用作通过修饰细胞骨架模式来调节细胞和组织结构的生理手段。