Jang Deok-Jin, Jun Yong-Woo, Shim Jaehoon, Sim Su-Eon, Lee Jin-A, Lim Chae-Seok, Kaang Bong-Kiun
Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, 2559, Gyeongsang-daero, Sangju-si, Gyeongsangbuk-do 37224, Republic of Korea.
Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, 2559, Gyeongsang-daero, Sangju-si, Gyeongsangbuk-do 37224, Republic of Korea.
Neurobiol Learn Mem. 2017 Feb;138:31-38. doi: 10.1016/j.nlm.2016.06.017. Epub 2016 Jun 21.
ADP-ribosylation factors (ARFs) are small guanosine triphosphatases of the Ras superfamily involved in membrane trafficking and regulation of the actin cytoskeleton. Aplysia Sec7 protein (ApSec7), a guanine nucleotide exchange factor for ARF1 and ARF6, induces neurite outgrowth and plays a key role in 5-hydroxyltryptamine-induced neurite growth and synaptic facilitation in Aplysia sensory-motor synapses. However, the specific role of ARF6 signaling on neurite outgrowth in Aplysia neurons has not been examined. In the present study, we cloned Aplysia ARF6 (ApARF6) and revealed that an overexpression of enhanced green fluorescent protein (EGFP)-fused constitutively active ApARF6 (ApARF6-Q67L-EGFP) could induce neurite outgrowth in Aplysia sensory neurons. Further, we observed that ApARF6-induced neurite outgrowth was inhibited by the co-expression of a Sec7 activity-deficient mutant of ApSec7 (ApSec7-E159K). The pleckstrin homology domain of ApSec7 may bind to active ApARF6 at the plasma membrane and prevent active ApARF6-induced functions, including intracellular vacuole formation in HEK293T cells. The results of the present study suggest that activation of ARF6 signaling could induce neurite outgrowth in Aplysia neurons and may be involved in downstream signaling of ApSec7-induced neurite outgrowth in Aplysia neurons.
ADP核糖基化因子（ARFs）是Ras超家族的小GTP酶，参与膜运输和肌动蛋白细胞骨架的调节。海兔Sec7蛋白（ApSec7）是ARF1和ARF6的鸟嘌呤核苷酸交换因子，可诱导神经突生长，并在5-羟色胺诱导的海兔感觉运动突触的神经突生长和突触易化中起关键作用。然而，ARF6信号在海兔神经元神经突生长中的具体作用尚未得到研究。在本研究中，我们克隆了海兔ARF6（ApARF6），并发现增强型绿色荧光蛋白（EGFP）融合的组成型活性ApARF6（ApARF6-Q67L-EGFP）的过表达可诱导海兔感觉神经元的神经突生长。此外，我们发现ApSec7的Sec7活性缺陷突变体（ApSec7-E159K）的共表达可抑制ApARF6诱导的神经突生长。ApSec7的普列克底物蛋白同源结构域可能在质膜上与活性ApARF6结合，并阻止活性ApARF6诱导的功能，包括HEK293T细胞中的细胞内液泡形成。本研究结果表明，ARF6信号的激活可诱导海兔神经元的神经突生长，并可能参与ApSec7诱导的海兔神经元神经突生长的下游信号传导。
