Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras 2781-901, Portugal.
Development. 2012 Feb;139(3):503-13. doi: 10.1242/dev.071027.
Epithelial cells mostly orient the spindle along the plane of the epithelium (planar orientation) for mitosis to produce two identical daughter cells. The correct orientation of the spindle relies on the interaction between cortical polarity components and astral microtubules. Recent studies in mammalian tissue culture cells suggest that the apically localised atypical protein kinase C (aPKC) is important for the planar orientation of the mitotic spindle in dividing epithelial cells. Yet, in chicken neuroepithelial cells, aPKC is not required in vivo for spindle orientation, and it has been proposed that the polarization cues vary between different epithelial cell types and/or developmental processes. In order to investigate whether Drosophila aPKC is required for spindle orientation during symmetric division of epithelial cells, we took advantage of a previously isolated temperature-sensitive allele of aPKC. We showed that Drosophila aPKC is required in vivo for spindle planar orientation and apical exclusion of Pins (Raps). This suggests that the cortical cues necessary for spindle orientation are not only conserved between Drosophila and mammalian cells, but are also similar to those required for spindle apicobasal orientation during asymmetric cell division.
上皮细胞通常使纺锤体沿上皮层的平面（平面取向）排列，以便在有丝分裂中产生两个相同的子细胞。纺锤体的正确取向依赖于皮质极性成分和星体微管之间的相互作用。最近在哺乳动物组织培养细胞中的研究表明，顶端局部化的非典型蛋白激酶 C（aPKC）对于分裂上皮细胞中有丝分裂纺锤体的平面取向很重要。然而，在鸡神经上皮细胞中，aPKC 在体内并不需要用于纺锤体定向，并且有人提出，极化线索在不同的上皮细胞类型和/或发育过程中是不同的。为了研究果蝇 aPKC 是否需要在上皮细胞的对称分裂期间进行纺锤体定向，我们利用了先前分离的 aPKC 温度敏感等位基因。我们表明，果蝇 aPKC 在体内对于纺锤体的平面取向和 Pins（Raps）的顶端排除是必需的。这表明，用于纺锤体定向的皮质线索不仅在果蝇和哺乳动物细胞之间保守，而且与在不对称细胞分裂过程中纺锤体顶端基底取向所需的线索相似。
