Multiphasic dynamics of phosphatidylinositol 4-phosphate during phagocytosis.
Multiphasic dynamics of phosphatidylinositol 4-phosphate during phagocytosis.
复制标题
吞噬作用期间4-磷酸磷脂酰肌醇的多相动力学。
DOI：
10.1091/mbc.e16-06-0451
复制
发表时间：
2017-01-01
影响因子：
3.3
通讯作者：
Grinstein S
中科院分区：
文献类型：
--
作者：
Levin R;Hammond GR;Balla T;De Camilli P;Fairn GD;Grinstein S
磷脂酰肌醇4-磷酸在吞噬体形成和成熟过程中经历了显著的多相变化。这些变化的分子机制和磷脂酰肌醇4-磷酸在吞噬溶酶体形成的作用进行了研究。我们分析了吞噬体形成和成熟过程中磷脂酰肌醇4-磷酸（PtdIns 4P）的分布、命运和功能作用。为此，我们使用由细菌效应子SidM的PtdIns 4P结合结构域组成的遗传编码探针。PtdIns 4P在吞噬过程中发生复杂的多相变化。在与靶颗粒接合之前存在于质膜中的磷酸肌醇在吞噬体杯中瞬时富集。吞噬体密封后不久，由于Sac 2和磷脂酶C的水解活性，PtdIns 4 P水平急剧下降，在10分钟内无法检测到。PtdIns 4 P的消失与吞噬体PtdIns 3 P的出现同时发生。相反，PtdIns 3 P的消失，信号从早期到晚期吞噬体的过渡是伴随着PtdIns 4P的复苏，这是与磷脂酰肌醇4-激酶2A的招聘。PtdIns 4P的重新获得可以通过沉默激酶的表达来防止，并且可以通过用异源二聚化系统募集4-磷酸酶来抵消。使用这些方法，我们发现PtdIns 4P的次级积累是适当的吞噬体酸化所必需的。缺陷性酸化可能是由于Rab 7效应物（包括RILP）的募集受损所致，RILP在早期被证明可将吞噬体置换为核周溶酶体。我们的研究结果表明，多模式动力学的PtdIns 4P在吞噬过程中，并建议磷酸肌醇在吞噬体的成熟过程中起着重要的作用。
Phosphatidylinositol 4-phosphate undergoes striking multiphasic changes during phagosome formation and maturation. The molecular mechanisms underlying these changes and the role of phosphatidylinositol 4-phosphate in phagolysosome formation are investigated. We analyzed the distribution, fate, and functional role of phosphatidylinositol 4-phosphate (PtdIns4P) during phagosome formation and maturation. To this end, we used genetically encoded probes consisting of the PtdIns4P-binding domain of the bacterial effector SidM. PtdIns4P was found to undergo complex, multiphasic changes during phagocytosis. The phosphoinositide, which is present in the plasmalemma before engagement of the target particle, is transiently enriched in the phagosomal cup. Soon after the phagosome seals, PtdIns4P levels drop precipitously due to the hydrolytic activity of Sac2 and phospholipase C, becoming undetectable for ∼10 min. PtdIns4P disappearance coincides with the emergence of phagosomal PtdIns3P. Conversely, the disappearance of PtdIns3P that signals the transition from early to late phagosomes is accompanied by resurgence of PtdIns4P, which is associated with the recruitment of phosphatidylinositol 4-kinase 2A. The reacquisition of PtdIns4P can be prevented by silencing expression of the kinase and can be counteracted by recruitment of a 4-phosphatase with a heterodimerization system. Using these approaches, we found that the secondary accumulation of PtdIns4P is required for proper phagosomal acidification. Defective acidification may be caused by impaired recruitment of Rab7 effectors, including RILP, which were shown earlier to displace phagosomes toward perinuclear lysosomes. Our results show multimodal dynamics of PtdIns4P during phagocytosis and suggest that the phosphoinositide plays important roles during the maturation of the phagosome.