Essential role for Abi1 in embryonic survival and WAVE2 complex integrity
Essential role for Abi1 in embryonic survival and WAVE2 complex integrity
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DOI：
10.1073/pnas.1016811108
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发表时间：
2011-04-26
影响因子：
11.1
通讯作者：
Kotula, Leszek
中科院分区：
文献类型：
--
作者：
Dubielecka, Patrycja M.;Ladwein, Kathrin I.;Kotula, Leszek
Abl interactor 1（Abi 1）通过参与WAVE 2复合物在肌动蛋白细胞骨架动力学中起关键作用。为了更好地理解Abi 1的特定作用，我们产生了条件性Abi 1-KO小鼠模型和缺乏Abi 1表达的MEFs。Abi 1-KO细胞显示肌动蛋白细胞骨架的调节缺陷，这种调节异常归因于WAVE 2复合物的活性改变。Abi 1-KO细胞运动性的变化表现为迁移率和距离降低，但方向持久性增加。虽然这些表型与外周皱褶无关，但不受影响，Abi 1-KO细胞表现出减少的背皱褶。Abi 1-KO细胞裂解物的蛋白质印迹分析表明WAVE复合物组分WAVE 1和WAVE 2、Nap 1和Sra-1/PIR 121的水平降低。尽管Abi 1-KO细胞中Abi 2的相对水平增加了一倍以上，但这些细胞中Abi 2的绝对表达量仅为对照细胞系中Abi 1水平的五分之一。这一发现表明Abi 1的存在对于WAVE复合物的完整性和稳定性至关重要，并且Abi 2水平没有充分增加以完全补偿KO细胞中Abi 1的损失并恢复WAVE复合物的完整性和功能。Abi 1在WAVE复合物中的基本功能及其调节可能解释了观察到的Abi 1缺陷胚胎的胚胎致死性，这些胚胎存活至大约胚胎第11.5天，并在发育中的心脏和大脑中显示畸形。缺乏Abi 1的细胞和条件Abi 1-KO小鼠将作为定义Abi 1功能的关键模型。
Abl interactor 1 (Abi1) plays a critical function in actin cytoskeleton dynamics through participation in the WAVE2 complex. To gain a better understanding of the specific role of Abi1, we generated a conditional Abi1-KO mouse model and MEFs lacking Abi1 expression. Abi1-KO cells displayed defective regulation of the actin cytoskeleton, and this dysregulation was ascribed to altered activity of the WAVE2 complex. Changes in motility of Abi1-KO cells were manifested by a decreased migration rate and distance but increased directional persistence. Although these phenotypes did not correlate with peripheral ruffling, which was unaffected, Abi1-KO cells exhibited decreased dorsal ruffling. Western blotting analysis of Abi1-KO cell lysates indicated reduced levels of the WAVE complex components WAVE1 and WAVE2, Nap1, and Sra-1/PIR121. Although relative Abi2 levels were more than doubled in Abi1-KO cells, the absolute Abi2 expression in these cells amounted only to a fifth of Abi1 levels in the control cell line. This finding suggests that the presence of Abi1 is critical for the integrity and stability of WAVE complex and that Abi2 levels are not sufficiently increased to compensate fully for the loss of Abi1 in KO cells and to restore the integrity and function of the WAVE complex. The essential function of Abi1 in WAVE complexes and their regulation might explain the observed embryonic lethality of Abi1-deficient embryos, which survived until approximately embryonic day 11.5 and displayed malformations in the developing heart and brain. Cells lacking Abi1 and the conditional Abi1-KO mouse will serve as critical models for defining Abi1 function.