A protein complex containing inscuteable and the Gα-binding protein Pins orients asymmetric cell divisions in Drosophila
A protein complex containing inscuteable and the Gα-binding protein Pins orients asymmetric cell divisions in Drosophila
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DOI：
10.1016/s0960-9822(00)00401-2
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发表时间：
2000-04-06
期刊：
影响因子：
9.2
通讯作者：
Knoblich, JA
中科院分区：
文献类型：
--
作者：
Schaefer, M;Shevchenko, A;Knoblich, JA
背景资料：在果蝇Drosophila中，Inscuteable蛋白定位于成神经细胞的顶端细胞皮层，并在有丝分裂期间指导有丝分裂纺锤体的顶端-基底取向和蛋白决定簇Numb和Prospero的基底定位。在成神经细胞分层过程中，通过直接结合Bazooka（一种顶部定位的蛋白质，包含称为PDZ结构域的蛋白质相互作用基序），启动了不对称定位。如何apically本地化的Inscuteable指导不对称的细胞divisions is uncleared.Results：一种新的70 kDa的蛋白质称为伙伴的Inscuteable（引脚）和异源三聚体G-蛋白a亚基被发现在体内特异性结合到功能域的Inscuteable。Pins的预测序列包含四方肽重复序列（TPR）和与结合Ga蛋白有关的基序。在间期和有丝分裂期的成神经细胞中，顶细胞皮质处的针与Inscuteable共定位。不对称定位钉需要隐形和火箭筒。在上皮细胞，不表达insuteable，针不是顶部本地化，但可以招募到顶端皮质异位表达的insuteable。在引脚突变体，这些上皮细胞不受影响，但成神经细胞显示缺陷的方向，其有丝分裂纺锤体和基础的不对称定位的Numb和米兰达在中期。虽然本地化的Inscuteable在引脚突变体中正确地启动在成神经细胞分层，Inscuteable成为均匀分布在细胞质中的有丝分裂during mitochondries.Conclusions：引脚和Inscuteable是相互依赖的分层的成神经细胞的不对称本地化。钉Ga蛋白的结合提供了有趣的可能性，即Inscuteable和钉可能通过定位或局部调节顶端细胞皮质的异源三聚体G蛋白信号级联来定向不对称细胞分裂。(C)2000爱思唯尔科技有限公司版权所有。
Background: in the fruit fly Drosophila, the Inscuteable protein localises to the apical cell cortex in neuroblasts and directs both the apical-basal orientation of the mitotic spindle and the basal localisation of the protein determinants Numb and Prospero during mitosis. Asymmetric localisation of Inscuteable is initiated during neuroblast delamination by direct binding to Bazooka, an apically localised protein that contains protein-interaction motifs known as PDZ domains. How apically localised Inscuteable directs asymmetric cell divisions is unclear.Results: A novel 70 kDa protein called Partner of Inscuteable (Pins) and a heterotrimeric G-protein a subunit were found to bind specifically to the functional domain of Inscuteable in vivo. The predicted sequence of Pins contained tetratrico-peptide repeats (TPRs) and motifs implicated in binding Ga proteins. Pins colocalised with Inscuteable at the apical cell cortex in interphase and mitotic neuroblasts. Asymmetric localisation of Pins required both Inscuteable and Bazooka. In epithelial cells, which do not express inscuteable, Pins was not apically localised but could be recruited to the apical cortex by ectopic expression of Inscuteable. In pins mutants, these epithelial cells were not affected, but neuroblasts showed defects in the orientation of their mitotic spindle and the basal asymmetric localisation of Numb and Miranda during metaphase. Although localisation of Inscuteable in pins mutants was initiated correctly during neuroblast delamination, Inscuteable became homogeneously distributed in the cytoplasm during mitosis.Conclusions: Pins and Inscuteable are dependent on each other for asymmetric localisation in delaminated neuroblasts. The binding of Pins to Ga protein offers the intriguing possibility that Inscuteable and Pins might orient asymmetric cell divisions by localising or locally modulating a heterotrimeric G-protein signalling cascade at the apical cell cortex. (C) 2000 Elsevier Science Ltd. All rights reserved.