Chen Lizhen, Chuang Marian, Koorman Thijs, Boxem Mike, Jin Yishi, Chisholm Andrew D
Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States.
University of California, San Diego, La Jolla, United States.
Elife. 2015 Sep 4;4:e08695. doi: 10.7554/eLife.08695.
Axon injury triggers a series of changes in the axonal cytoskeleton that are prerequisites for effective axon regeneration. In Caenorhabditis elegans the signaling protein Exchange Factor for ARF-6 (EFA-6) is a potent intrinsic inhibitor of axon regrowth. Here we show that axon injury triggers rapid EFA-6-dependent inhibition of axonal microtubule (MT) dynamics, concomitant with relocalization of EFA-6. EFA-6 relocalization and axon regrowth inhibition require a conserved 18-aa motif in its otherwise intrinsically disordered N-terminal domain. The EFA-6 N-terminus binds the MT-associated proteins TAC-1/Transforming-Acidic-Coiled-Coil, and ZYG-8/Doublecortin-Like-Kinase, both of which are required for regenerative growth cone formation, and which act downstream of EFA-6. After injury TAC-1 and EFA-6 transiently relocalize to sites marked by the MT minus end binding protein PTRN-1/Patronin. We propose that EFA-6 acts as a bifunctional injury-responsive regulator of axonal MT dynamics, acting at the cell cortex in the steady state and at MT minus ends after injury.
轴突损伤会引发轴突细胞骨架的一系列变化,这些变化是有效轴突再生的先决条件。在秀丽隐杆线虫中,ARF-6交换因子(EFA-6)这种信号蛋白是轴突再生的一种强大的内在抑制剂。在这里,我们表明轴突损伤会引发依赖EFA-6的轴突微管(MT)动力学的快速抑制,并伴随着EFA-6的重新定位。EFA-6的重新定位和轴突再生抑制需要其原本无序的N端结构域中一个保守的18个氨基酸的基序。EFA-6的N端与微管相关蛋白TAC-1/转化酸性卷曲螺旋蛋白以及ZYG-8/双皮质素样激酶结合,这两种蛋白都是再生生长锥形成所必需的,并且在EFA-6的下游发挥作用。损伤后,TAC-1和EFA-6会短暂地重新定位于由微管负端结合蛋白PTRN-1/帕托宁标记的位点。我们提出,EFA-6作为轴突微管动力学的双功能损伤反应调节因子,在稳态下作用于细胞皮层,在损伤后作用于微管负端。