Regulation of Macropinocytosis by Diacylglycerol Kinase ζ.
Regulation of Macropinocytosis by Diacylglycerol Kinase ζ.
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DOI：
10.1371/journal.pone.0144942
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Gee SH
中科院分区：
文献类型：
--
作者：
Ard R;Mulatz K;Pomoransky JL;Parks RJ;Trinkle-Mulcahy L;Bell JC;Gee SH
大胞饮体产生于质膜皱褶的闭合，从而使营养物质和溶质非选择性地吸收到细胞中。褶皱形成和大胞饮体生物发生的形态学变化是由肌动蛋白细胞骨架重排的Rho GTdR Rac 1的控制下。我们以前表明，Rac 1是由二酰基甘油激酶β（DGK β），磷酸化二酰基甘油，产生磷脂酸激活。在这里，我们表明DGK β是所需的最佳巨胞饮诱导的生长因子刺激小鼠胚胎成纤维细胞。活细胞的延时成像和定量分析显示，DGK-peptide与膜皱褶和新生的巨胞饮体有关。如通过活成像和牛痘病毒摄取实验所确定的，在DGK β-null细胞中巨胞饮减弱。此外，在DGK β-null细胞中确实形成的大胞饮体比在野生型细胞中发现的那些小。挽救该缺陷需要DGK-R催化活性，这与Rac 1活化也需要DGK-R催化活性一致。一个组成性的膜结合DGK的突变体大大增加了大胞饮体的大小，并加强了组成性活性的Rac 1突变体对巨胞饮的影响。总的来说，我们的研究结果表明，DGK β功能与Rac 1协调调节巨胞饮作用。
Macropinosomes arise from the closure of plasma membrane ruffles to bring about the non-selective uptake of nutrients and solutes into cells. The morphological changes underlying ruffle formation and macropinosome biogenesis are driven by actin cytoskeleton rearrangements under the control of the Rho GTPase Rac1. We showed previously that Rac1 is activated by diacylglycerol kinase ζ (DGKζ), which phosphorylates diacylglycerol to yield phosphatidic acid. Here, we show DGKζ is required for optimal macropinocytosis induced by growth factor stimulation of mouse embryonic fibroblasts. Time-lapse imaging of live cells and quantitative analysis revealed DGKζ was associated with membrane ruffles and nascent macropinosomes. Macropinocytosis was attenuated in DGKζ-null cells, as determined by live imaging and vaccinia virus uptake experiments. Moreover, macropinosomes that did form in DGKζ-null cells were smaller than those found in wild type cells. Rescue of this defect required DGKζ catalytic activity, consistent with it also being required for Rac1 activation. A constitutively membrane bound DGKζ mutant substantially increased the size of macropinosomes and potentiated the effect of a constitutively active Rac1 mutant on macropinocytosis. Collectively, our results suggest DGKζ functions in concert with Rac1 to regulate macropinocytosis.