Skop A R, White J G
Laboratory of Molecular Biology University of Wisconsin-Madison Madison, Wisconsin 53706, USA.
Curr Biol. 1998 Oct 8;8(20):1110-6. doi: 10.1016/s0960-9822(98)70465-8.
During metazoan development, cell diversity arises primarily from asymmetric cell divisions which are executed in two phases: segregation of cytoplasmic factors and positioning of the mitotic spindle - and hence the cleavage plane -relative to the axis of segregation. When polarized cells divide, spindle alignment probably occurs through the capture and subsequent shortening of astral microtubules by a site in the cortex.
Here, we report that dynactin, the dynein-activator complex, is localized at cortical microtubule attachment sites and is necessary for mitotic spindle alignment in early Caenorhabditis elegans embryos. Using RNA interference techniques, we eliminated expression in early embryos of dnc-1 (the ortholog of the vertebrate gene for p150(Glued)) and dnc-2 (the ortholog of the vertebrate gene for p50/Dynamitin). In both cases, misalignment of mitotic spindles occurred, demonstrating that two components of the dynactin complex, DNC-1 and DNC-2, are necessary to align the spindle.
Dynactin complexes may serve as a tether for dynein at the cortex and allow dynein to produce forces on the astral microtubules required for mitotic spindle alignment.
在后生动物发育过程中，细胞多样性主要源于不对称细胞分裂，其分为两个阶段进行：细胞质因子的分离以及有丝分裂纺锤体（进而分裂平面）相对于分离轴的定位。当极化细胞分裂时，纺锤体排列可能是通过星状微管被皮层中的一个位点捕获并随后缩短来实现的。
在此，我们报道动力蛋白激活复合物动力蛋白激活蛋白定位于皮层微管附着位点，并且对于秀丽隐杆线虫早期胚胎中的有丝分裂纺锤体排列是必需的。使用RNA干扰技术，我们消除了dnc-1（脊椎动物p150(Glued)基因的直系同源基因）和dnc-2（脊椎动物p50/动力蛋白抑制因子基因的直系同源基因）在早期胚胎中的表达。在这两种情况下，均出现了有丝分裂纺锤体排列错误，表明动力蛋白激活蛋白复合物的两个组分DNC-1和DNC-2对于纺锤体排列是必需的。
动力蛋白激活蛋白复合物可能作为皮层中动力蛋白的系链，并允许动力蛋白对有丝分裂纺锤体排列所需的星状微管产生作用力。
