Peitsch Wiebke K, Bulkescher Jutta, Spring Herbert, Hofmann Ilse, Goerdt Sergij, Franke Werner W
Department of Dermatology, Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.
Exp Cell Res. 2006 Aug 1;312(13):2605-18. doi: 10.1016/j.yexcr.2006.04.017. Epub 2006 May 11.
The actin-binding protein (ABP) drebrin, isoform E2, is involved in remodelling of the actin cytoskeleton and in formation of cell processes, but its role in cell migration has not yet been investigated. Therefore, we have studied the organization of drebrin in motile cultured cells such as murine B16F1 melanoma and human SV80 fibroblast cells, using live cell confocal microscopy. In cells overexpressing DNA constructs encoding drebrin linked to EGFP, numerous long, branched cell processes were formed which slowly retracted and extended, whereas forward movement was halted. In contrast, stably transfected B16F1 cells containing drebrin-EGFP at physiological levels displayed lamellipodia and were able to migrate on laminin. Surprisingly, in such cells, drebrin was absent from anterior lamellipodia but was enriched in a specific juxtanuclear zone, the "drebrin-enriched zone" (DZ), and in the tail. In leading edges of SV80 cells, characterized by pronounced actin microspikes, drebrin was specifically enriched along posterior portions of the microspikes, together with tropomyosin. Drebrin knock-down by small interfering RNAs did not impair movements of SV80 cells. Our results confirm the role of drebrin E2 in the formation of branching processes and further indicate that during cell migration, the protein contributes to retraction of the cell body and the tail but not to lamellipodia formation. In particular, the novel, sizable juxtanuclear DZ structure will have to be characterized in future experiments with respect to its molecular assembly and cell biological functions.
肌动蛋白结合蛋白（ABP） drebrin的E2亚型参与肌动蛋白细胞骨架的重塑和细胞突起的形成，但其在细胞迁移中的作用尚未得到研究。因此，我们利用活细胞共聚焦显微镜研究了drebrin在运动的培养细胞中的组织情况，如小鼠B16F1黑色素瘤细胞和人SV80成纤维细胞。在过表达编码与EGFP相连的drebrin的DNA构建体的细胞中，形成了许多长的、分支的细胞突起，这些突起缓慢回缩和伸展，而向前运动则停止。相反，稳定转染了生理水平drebrin-EGFP的B16F1细胞显示出片状伪足，并且能够在层粘连蛋白上迁移。令人惊讶的是，在这类细胞中，drebrin在前部片状伪足中不存在，但在一个特定的近核区域，即“drebrin富集区”（DZ）以及尾部中富集。在以明显的肌动蛋白微刺为特征的SV80细胞的前缘，drebrin与原肌球蛋白一起特异性地富集在微刺的后部。用小干扰RNA敲低drebrin并不损害SV80细胞的运动。我们的结果证实了drebrin E2在分支突起形成中的作用，并进一步表明在细胞迁移过程中，该蛋白有助于细胞体和尾部的回缩，但对片状伪足的形成没有贡献。特别是，关于其分子组装和细胞生物学功能，这个新的、相当大的近核DZ结构将必须在未来的实验中进行表征。
