Negative Regulation of the Endocytic Adaptor Disabled-2 (Dab2) in Mitosis
Negative Regulation of the Endocytic Adaptor Disabled-2 (Dab2) in Mitosis
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DOI：
10.1074/jbc.m110.161851
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发表时间：
2011-02-18
影响因子：
4.8
通讯作者：
Ehrlich, Marcelo
中科院分区：
文献类型：
--
作者：
Chetrit, David;Barzilay, Lior;Ehrlich, Marcelo
有丝分裂细胞通过改变其膜运输机制的调节和功能而经历形状和大小的广泛变化。Disabled 2（Dab 2）是一种多结构域的货物特异性内吞衔接子和信号转导介体，是运输和信号转导的潜在整合者。Dab 2结合定位于不同细胞内区室的信号传导和运输效应子。因此，差异定位是Dab 2功能的一种公认的调节机制。此外，Dab 2在有丝分裂中被磷酸化，因此在细胞周期中受到调节。然而，Dab 2在有丝分裂的不同阶段的细胞内定位的详细描述和其磷酸化的功能后果的理解是缺乏的。在这里，我们表明，Dab 2是逐步从有丝分裂的膜位移。这种现象被与网格蛋白的共定位的损失所掩盖。这两种现象在中期/后期达到高潮，并在胞质分裂中部分恢复。用2-甲氧基乙烯醇处理，其在纺锤体组装检查点处逮捕细胞，诱导在中期细胞中观察到的相同效果。此外，2-甲氧基紫杉醇还诱导Dab 2磷酸化，并减少Dab 2/网格蛋白相互作用，内吞囊泡运动，网格蛋白交换动力学，和具有NPXY内吞信号的受体的内化。丝氨酸/苏氨酸到丙氨酸的突变，定位于Dab 2的中心区域的残基，减弱其磷酸化，减少其膜位移，并保持其在有丝分裂中的内吞能力。我们认为Dab 2的负调控是细胞适应有丝分裂中普遍存在的改变的物理化学条件的一部分，目的是允许在整个细胞周期中的内吞活性。
Mitotic cells undergo extensive changes in shape and size through the altered regulation and function of their membrane trafficking machinery. Disabled 2 (Dab2), a multidomain cargo-specific endocytic adaptor and a mediator of signal transduction, is a potential integrator of trafficking and signaling. Dab2 binds effectors of signaling and trafficking that localize to different intracellular compartments. Thus, differential localization is a putative regulatory mechanism of Dab2 function. Furthermore, Dab2 is phosphorylated in mitosis and is thus regulated in the cell cycle. However, a detailed description of the intracellular localization of Dab2 in the different phases of mitosis and an understanding of the functional consequences of its phosphorylation are lacking. Here, we show that Dab2 is progressively displaced from the membrane in mitosis. This phenomenon is paralleled by a loss of co-localization with clathrin. Both phenomena culminate in metaphase/anaphase and undergo partial recovery in cytokinesis. Treatment with 2-methoxyestradiol, which arrests cells at the spindle assembly checkpoint, induces the same effects observed in metaphase cells. Moreover, 2-methoxyestradiol also induced Dab2 phosphorylation and reduced Dab2/clathrin interactions, endocytic vesicle motility, clathrin exchange dynamics, and the internalization of a receptor endowed with an NPXY endocytic signal. Serine/threonine to alanine mutations, of residues localized to the central region of Dab2, attenuated its phosphorylation, reduced its membrane displacement, and maintained its endocytic abilities in mitosis. We propose that the negative regulation of Dab2 is part of an accommodation of the cell to the altered physicochemical conditions prevalent in mitosis, aimed at allowing endocytic activity throughout the cell cycle.