Peng C Y, Manning L, Albertson R, Doe C Q
Howard Hughes Medical Institute, University of Oregon, Eugene 97403, USA.
Nature. 2000 Nov 30;408(6812):596-600. doi: 10.1038/35046094.
Drosophila neuroblasts are a model system for studying asymmetric cell division: they divide unequally to produce an apical neuroblast and a basal ganglion mother cell that differ in size, mitotic activity and developmental potential. During neuroblast mitosis, an apical protein complex orients the mitotic spindle and targets determinants of cell fate to the basal cortex, but the mechanism of each process is unknown. Here we show that the tumour-suppressor genes lethal giant larvae (lgl) and discs large (dlg) regulate basal protein targeting, but not apical complex formation or spindle orientation, in both embryonic and larval neuroblasts. Dlg protein is apically enriched and is required for maintaining cortical localization of Lgl protein. Basal protein targeting requires microfilament and myosin function, yet the lgl phenotype is strongly suppressed by reducing levels of myosin II. We conclude that Dlg and Lgl promote, and myosin II inhibits, actomyosin-dependent basal protein targeting in neuroblasts.
它们进行不均等分裂，产生大小、有丝分裂活性和发育潜能不同的顶端神经母细胞和基底神经节母细胞。在神经母细胞有丝分裂期间，一个顶端蛋白复合体使有丝分裂纺锤体定向，并将细胞命运决定因子靶向基底皮质，但每个过程的机制尚不清楚。在这里，我们表明肿瘤抑制基因致死性巨幼虫（lgl）和盘状大蛋白（dlg）在胚胎和幼虫神经母细胞中调节基底蛋白靶向，但不调节顶端复合体形成或纺锤体定向。Dlg蛋白在顶端富集，是维持Lgl蛋白皮质定位所必需的。基底蛋白靶向需要微丝和肌球蛋白功能，然而通过降低肌球蛋白II的水平，lgl表型受到强烈抑制。我们得出结论，Dlg和Lgl促进，而肌球蛋白II抑制神经母细胞中肌动球蛋白依赖性的基底蛋白靶向。
