Phosphatidylinositol 3-Kinase Facilitates Microtubule-dependent Membrane Transport for Neuronal Growth Cone Guidance
Phosphatidylinositol 3-Kinase Facilitates Microtubule-dependent Membrane Transport for Neuronal Growth Cone Guidance
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DOI：
10.1074/jbc.m110.156489
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发表时间：
2010-12-31
影响因子：
4.8
通讯作者：
Kamiguchi, Hiroyuki
中科院分区：
文献类型：
--
作者：
Akiyama, Hiroki;Kamiguchi, Hiroyuki
PI3K的活性是极化细胞运动所必需的。为了引导轴突的延伸，环境线索通过不对称产生Ca2+信号和随后的细胞内机械事件，包括膜运输和细胞骨架重组，使生长锥极化。然而，目前尚不清楚PI3K如何参与轴突引导的这些事件。在这里，我们证明PI3K通过促进微管（MT）依赖的膜运输，在生长锥转向中发挥许可作用。利用培养的胚胎鸡背根神经节神经元，通过光解笼中Ca2+或笼中肌醇1,4,5-三磷酸，在生长锥一侧升高Ca2+诱导轴突转向。我们发现PI3K活性是Ca2+信号下游生长锥转向所必需的。有吸引力的Ca2+信号，由Ca2+或肌醇1,4,5-三磷酸产生，以mt依赖的方式触发膜泡从生长锥中心到外围的不对称运输。这种离心囊泡运输被PI3K抑制剂所消除，这表明PI3K在膜运输水平上参与了生长锥吸引。与这一观察结果一致，免疫细胞化学显示PI3K抑制剂减少了生长锥外周区域的mt。MTs正端的EB1延时成像显示，MT进入生长锥体外周结构域依赖于PI3K的活性：PI3K信号通路的抑制减弱了MT的推进，而PI3K催化反应的产物外源磷脂酰肌醇3,4,5-三磷酸促进了MT的推进。这项研究证明了pi3k依赖的膜运输在趋化细胞迁移中的重要性。
The activity of PI3K is necessary for polarized cell motility. To guide extending axons, environmental cues polarize the growth cone via asymmetric generation of Ca2+ signals and subsequent intracellular mechanical events, including membrane trafficking and cytoskeletal reorganization. However, it remains unclear how PI3K is involved in such events for axon guidance. Here, we demonstrate that PI3K plays a permissive role in growth cone turning by facilitating microtubule (MT)dependent membrane transport. Using embryonic chick dorsal root ganglion neurons in culture, attractive axon turning was induced by Ca2+ elevations on one side of the growth cone by photolyzing caged Ca2+ or caged inositol 1,4,5-trisphosphate. We show that PI3K activity was required downstream of Ca2+ signals for growth cone turning. Attractive Ca2+ signals, generated with caged Ca2+ or caged inositol 1,4,5-trisphosphate, triggered asymmetric transport of membrane vesicles from the center to the periphery of growth cones in a MT-dependent manner. This centrifugal vesicle transport was abolished by PI3K inhibitors, suggesting that PI3K is involved in growth cone attraction at the level of membrane trafficking. Consistent with this observation, immunocytochemistry showed that PI3K inhibitors reduced MTs in the growth cone peripheral domain. Time-lapse imaging of EB1 on the plus-end of MTs revealed that MT advance into the growth cone peripheral domain was dependent on PI3K activity: inhibition of the PI3K signaling pathway attenuated MT advance, whereas exogenous phosphatidylinositol 3,4,5-trisphosphate, the product of PI3K-catalyzed reactions, promoted MT advance. This study demonstrates the importance of PI3K-dependent membrane trafficking in chemotactic cell migration.