Wodarz A, Ramrath A, Grimm A, Knust E
Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.
J Cell Biol. 2000 Sep 18;150(6):1361-74. doi: 10.1083/jcb.150.6.1361.
The establishment and maintenance of polarity is of fundamental importance for the function of epithelial and neuronal cells. In Drosophila, the multi-PDZ domain protein Bazooka (Baz) is required for establishment of apico-basal polarity in epithelia and in neuroblasts, the stem cells of the central nervous system. In the latter, Baz anchors Inscuteable in the apical cytocortex, which is essential for asymmetric localization of cell fate determinants and for proper orientation of the mitotic spindle. Here we show that Baz directly binds to the Drosophila atypical isoform of protein kinase C and that both proteins are mutually dependent on each other for correct apical localization. Loss-of-function mutants of the Drosophila atypical isoform of PKC show loss of apico-basal polarity, multilayering of epithelia, mislocalization of Inscuteable and abnormal spindle orientation in neuroblasts. Together, these data provide strong evidence for the existence of an evolutionary conserved mechanism that controls apico-basal polarity in epithelia and neuronal stem cells. This study is the first functional analysis of an atypical protein kinase C isoform using a loss-of-function allele in a genetically tractable organism.
极性的建立和维持对于上皮细胞和神经元细胞的功能至关重要。在果蝇中，多PDZ结构域蛋白巴祖卡（Baz）是上皮细胞和神经母细胞（中枢神经系统的干细胞）中顶-基极性建立所必需的。在后者中，Baz将Inscuteable锚定在顶端细胞皮质中，这对于细胞命运决定因子的不对称定位和有丝分裂纺锤体的正确定向至关重要。在这里，我们表明Baz直接与果蝇非典型蛋白激酶C亚型结合，并且这两种蛋白在正确的顶端定位上相互依赖。果蝇PKC非典型亚型的功能丧失突变体表现出顶-基极性丧失、上皮细胞多层化、Inscuteable定位错误以及神经母细胞中纺锤体定向异常。这些数据共同为存在一种控制上皮细胞和神经元干细胞中顶-基极性的进化保守机制提供了有力证据。这项研究是首次在遗传易处理的生物体中使用功能丧失等位基因对非典型蛋白激酶C亚型进行功能分析。
