Dugina Vera, Zwaenepoel Ingrid, Gabbiani Giulio, Clément Sophie, Chaponnier Christine
Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.
J Cell Sci. 2009 Aug 15;122(Pt 16):2980-8. doi: 10.1242/jcs.041970. Epub 2009 Jul 28.
Using newly generated monoclonal antibodies, we have compared the distribution of beta- and gamma-cytoplasmic actin in fibroblastic and epithelial cells, in which they play crucial roles during various key cellular processes. Whereas beta-actin is preferentially localized in stress fibers, circular bundles and at cell-cell contacts, suggesting a role in cell attachment and contraction, gamma-actin displays a more versatile organization, according to cell activities. In moving cells, gamma-actin is mainly organized as a meshwork in cortical and lamellipodial structures, suggesting a role in cell motility; in stationary cells, gamma-actin is also recruited into stress fibers. beta-actin-depleted cells become highly spread, display broad protrusions and reduce their stress-fiber content; by contrast, gamma-actin-depleted cells acquire a contractile phenotype with thick actin bundles and shrinked lamellar and lamellipodial structures. Moreover, beta- and gamma-actin depleted fibroblasts exhibit distinct changes in motility compared with their controls, suggesting a specific role for each isoform in cell locomotion. Our results reveal new aspects of beta- and gamma-actin organization that support their functional diversity.
利用新产生的单克隆抗体，我们比较了β-和γ-细胞质肌动蛋白在成纤维细胞和上皮细胞中的分布情况，它们在各种关键细胞过程中发挥着关键作用。β-肌动蛋白优先定位于应力纤维、环状束和细胞间接触部位，表明其在细胞黏附和收缩中发挥作用；而γ-肌动蛋白则根据细胞活动呈现出更为多样的组织形式。在移动的细胞中，γ-肌动蛋白主要组织成皮质和片状伪足结构中的网络，表明其在细胞运动中发挥作用；在静止的细胞中，γ-肌动蛋白也被募集到应力纤维中。β-肌动蛋白缺失的细胞变得高度铺展，呈现出宽阔的突起并减少其应力纤维含量；相比之下，γ-肌动蛋白缺失的细胞获得了具有粗大肌动蛋白束以及收缩的片状和片状伪足结构的收缩表型。此外，与对照相比，β-和γ-肌动蛋白缺失的成纤维细胞在运动性方面表现出明显不同的变化，表明每种异构体在细胞运动中具有特定作用。我们的结果揭示了β-和γ-肌动蛋白组织的新方面，支持了它们的功能多样性。
