ACAP3 regulates neurite outgrowth through its GAP activity specific to Arf6 in mouse hippocampal neurons.
ACAP3 regulates neurite outgrowth through its GAP activity specific to Arf6 in mouse hippocampal neurons.
复制标题
ACAP3 通过其对小鼠海马神经元中 Arf6 特有的 GAP 活性来调节神经突生长。
DOI：
10.1042/bcj20160183
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发表时间：
2016
影响因子：
4.1
通讯作者：
Kanaho Y.
中科院分区：
文献类型：
--
作者：
Miura Y;Hongu T;Yamauchi Y;Funakoshi Y;Katagiri N;Ohbayashi N;Kanaho Y.
ACAP3 （ArfGAP具有coil -coil， ankyrin repeat和pleckstrin同源结构域3）属于GTPase小分子Arf （adp -核糖基化因子）的GTPase激活蛋白ACAP家族。然而，其对Arf亚型的特异性和生理功能尚不清楚。在本研究中，我们发现ACAP3通过其针对Arf6的GAP活性在小鼠海马神经元的突起生长中发挥重要作用。在原代培养的小鼠海马神经元中，ACAP3的敲除会破坏神经突的生长，这是由异位表达的野生型ACAP3修复的，而不是由其GAP活性缺陷突变体修复的。异位表达ACAP3的HEK（人胚胎肾）-293T细胞显示出Arf6特异性的GAP活性。支持这一观察结果的是，gtp结合的Arf6水平通过敲低海马神经元ACAP3而显著升高。此外，敲低和敲除小鼠海马神经元中的Arf6可抑制神经突的生长。这些结果表明，ACAP3通过其Arf6特异性的GAP活性正向调节神经突生长。此外，ACAP3敲除抑制的神经突生长通过Arf6的快速周期突变体的表达得以恢复，该突变体在Arf6上自发交换鸟嘌呤核苷酸，而野生型、GTP或gdp锁定突变体Arf6则不能。因此，由ACAP3与鸟嘌呤-核苷酸交换因子（鸟嘌呤-核苷酸交换因子）精确调控的Arf6活性和非活性形式之间的循环似乎是海马神经元神经突生长所必需的。
ACAP3 (ArfGAP with coiled-coil, ankyrin repeat and pleckstrin homology domains 3) belongs to the ACAP family of GAPs (GTPase-activating proteins) for the small GTPase Arf (ADP-ribosylation factor). However, its specificity to Arf isoforms and physiological functions remain unclear. In the present study, we demonstrate that ACAP3 plays an important role in neurite outgrowth of mouse hippocampal neurons through its GAP activity specific to Arf6. In primary cultured mouse hippocampal neurons, knockdown of ACAP3 abrogated neurite outgrowth, which was rescued by ectopically expressed wild-type ACAP3, but not by its GAP activity-deficient mutant. Ectopically expressed ACAP3 in HEK (human embryonic kidney)-293T cells showed the GAP activity specific to Arf6. In support of this observation, the level of GTP-bound Arf6 was significantly increased by knockdown of ACAP3 in hippocampal neurons. In addition, knockdown and knockout of Arf6 in mouse hippocampal neurons suppressed neurite outgrowth. These results demonstrate that ACAP3 positively regulates neurite outgrowth through its GAP activity specific to Arf6. Furthermore, neurite outgrowth suppressed by ACAP3 knockdown was rescued by expression of a fast cycle mutant of Arf6 that spontaneously exchanges guanine nucleotides on Arf6, but not by that of wild-type, GTP- or GDP-locked mutant Arf6. Thus cycling between active and inactive forms of Arf6, which is precisely regulated by ACAP3 in concert with a guanine-nucleotide-exchange factor(s), seems to be required for neurite outgrowth of hippocampal neurons.