Sarma Tulika, Voyno-Yasenetskaya Tatyana, Hope Thomas J, Rasenick Mark M
Department of Physiology, College of Medicine, Chicago, Illinois 60612-7342, USA.
FASEB J. 2003 May;17(8):848-59. doi: 10.1096/fj.02-0730com.
Tubulin modifies G-protein signaling and heterotrimeric G-proteins regulate microtubule assembly. Here we report an interplay among G-protein-coupled receptor and receptor tyrosine kinase (such as nerve growth factor-NGF) signaling systems in PC12 pheochromocytoma cells that resulted in a translocation of Galpha(s), Galpha(i1), and Galpha(o) from cell bodies to cellular processes where they appear to localize with tubulin-containing structures. This relocation appeared to depend on the integrity of microtubules, as it was blocked and reversed by nocodazole. Latrunculin, which promotes actin filament depolymerization, had no effect. Both deconvolution microscopy and immunoprecipitation showed a significant increase of Galpha association with microtubules that was coincident with the extension of "neurites." There were distinctions among the Galpha subtypes, with Galpha(s) showing the most profound NGF-induced colocalization with tubulin. Translocation of Galpha was blocked by agents that inhibit the MAP kinases required for neuronal differentiation, suggesting that G-protein relocation is triggered by the intracellular signals for differentiation. Consistent with this, Galpha in Neuro-2A cells, which spontaneously differentiate, showed a similar translocation coincident with differentiation. Thus, diverse signals that promote neuronal differentiation and changes in cell morphology may use specific G-proteins to evoke cytoskeletal rearrangement.
微管蛋白修饰G蛋白信号传导，而异三聚体G蛋白调节微管组装。在此，我们报告了PC12嗜铬细胞瘤细胞中G蛋白偶联受体和受体酪氨酸激酶（如神经生长因子 - NGF）信号系统之间的相互作用，这导致Gα(s)、Gα(i1)和Gα(o)从细胞体转移到细胞突起，在那里它们似乎与含微管蛋白的结构共定位。这种重新定位似乎取决于微管的完整性，因为它被诺考达唑阻断并逆转。促进肌动蛋白丝解聚的拉春库林没有效果。去卷积显微镜和免疫沉淀均显示，Gα与微管的结合显著增加，这与“神经突”的延伸同时发生。Gα亚型之间存在差异，Gα(s)显示出最显著的NGF诱导的与微管蛋白的共定位。Gα的易位被抑制神经元分化所需的MAP激酶的试剂阻断，这表明G蛋白的重新定位是由分化的细胞内信号触发的。与此一致的是，自发分化的Neuro-2A细胞中的Gα显示出与分化同时发生的类似易位。因此，促进神经元分化和细胞形态变化的多种信号可能利用特定的G蛋白来引发细胞骨架重排。
