Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
Cell Rep. 2024 Sep 24;43(9):114666. doi: 10.1016/j.celrep.2024.114666. Epub 2024 Aug 24.
The exon junction complex (EJC), nucleated by EIF4A3, is indispensable for mRNA fate and function throughout eukaryotes. We discover that EIF4A3 directly controls microtubules, independent of RNA, which is critical for neural wiring. While neuronal survival in the developing mouse cerebral cortex depends upon an intact EJC, axonal tract development requires only Eif4a3. Using human cortical organoids, we show that EIF4A3 disease mutations also impair neuronal growth, highlighting conserved functions relevant for neurodevelopmental pathology. Live imaging of growing neurons shows that EIF4A3 is essential for microtubule dynamics. Employing biochemistry and competition experiments, we demonstrate that EIF4A3 directly binds to microtubules, mutually exclusive of the EJC. Finally, in vitro reconstitution assays and rescue experiments demonstrate that EIF4A3 is sufficient to promote microtubule polymerization and that EIF4A3-microtubule association is a major contributor to axon growth. This reveals a fundamental mechanism by which neurons re-utilize core gene expression machinery to directly control the cytoskeleton.
外显子连接复合物（EJC）由 EIF4A3 引发，对于真核生物中 mRNA 的命运和功能至关重要。我们发现 EIF4A3 可独立于 RNA 直接控制微管，这对于神经布线至关重要。虽然发育中的小鼠大脑皮层中的神经元存活依赖于完整的 EJC，但轴突束的发育仅需要 Eif4a3。使用人类皮质类器官，我们表明 EIF4A3 疾病突变也会损害神经元的生长，突出了与神经发育病理学相关的保守功能。生长神经元的实时成像表明，EIF4A3 对于微管动力学是必需的。通过生物化学和竞争实验，我们证明 EIF4A3 可直接结合微管，与 EJC 互斥。最后，体外重组测定和挽救实验表明，EIF4A3 足以促进微管聚合，并且 EIF4A3-微管的结合是轴突生长的主要贡献者。这揭示了神经元重新利用核心基因表达机制直接控制细胞骨架的基本机制。
