Zouwail Soha, Pettitt Trevor R, Dove Stephen K, Chibalina Margarita V, Powner Dale J, Haynes Lee, Wakelam Michael J O, Insall Robert H
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Biochem J. 2005 Jul 1;389(Pt 1):207-14. doi: 10.1042/BJ20050085.
PLD (phospholipase D) activity catalyses the generation of the lipid messenger phosphatidic acid, which has been implicated in a number of cellular processes, particularly the regulation of membrane traffic. In the present study, we report that disruption of PLD signalling causes unexpectedly profound effects on the actin-based motility of Dictyostelium. Cells in which PLD activity is inhibited by butan-1-ol show a complete loss of actin-based structures, accompanied by relocalization of F-actin into small clusters, and eventually the nucleus, without a visible fall in levels of F-actin. Addition of exogenous phosphatidic acid reverses the effects of butan-1-ol, confirming that these effects are caused by inhibition of PLD. Loss of motility correlates with complete inhibition of endocytosis and a reduction in phagocytosis. Inhibition of PLD caused a major decrease in the synthesis of PtdIns(4,5)P2, which could again be reversed by exogenously applied phosphatidic acid. Thus the essential role of PLD signalling in both motility and endocytosis appears to be mediated directly via regulation of PtdIns(4)P kinase activity. This implies that localized PLD-regulated synthesis of PtdIns(4,5)P2 is essential for Dictyostelium actin function.
磷脂酶D（PLD）活性催化脂质信使磷脂酸的生成，磷脂酸参与了许多细胞过程，特别是膜运输的调节。在本研究中，我们报告PLD信号的破坏对盘基网柄菌基于肌动蛋白的运动产生了意想不到的深远影响。用1-丁醇抑制PLD活性的细胞显示基于肌动蛋白的结构完全丧失，伴随着F-肌动蛋白重新定位到小簇中，最终进入细胞核，而F-肌动蛋白水平没有明显下降。添加外源性磷脂酸可逆转1-丁醇的作用，证实这些作用是由PLD抑制引起的。运动能力的丧失与内吞作用的完全抑制和吞噬作用的减少相关。PLD的抑制导致磷脂酰肌醇-4,5-二磷酸（PtdIns(4,5)P2）合成的大幅下降，外源性应用磷脂酸可再次逆转这种下降。因此，PLD信号在运动和内吞作用中的重要作用似乎直接通过调节磷脂酰肌醇-4-磷酸（PtdIns(4)P）激酶活性来介导。这意味着局部PLD调节的PtdIns(4,5)P2合成对于盘基网柄菌的肌动蛋白功能至关重要。
