Role of RhoA in activity-dependent cortical axon branching
Role of RhoA in activity-dependent cortical axon branching
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DOI：
10.1523/jneurosci.1731-08.2008
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发表时间：
2008-09-10
影响因子：
5.3
通讯作者：
Yamamoto, Nobuhiko
中科院分区：
文献类型：
--
作者：
Ohnami, Soichiro;Endo, Mitsuharu;Yamamoto, Nobuhiko
在发育过程中，轴突分支受到感觉诱发和自发神经活动的影响。我们研究的分子机制，活动依赖性分支的形成在水平伸长的轴突（水平轴突）在上皮层，重点是Rho家族的小GTP酶。用增强型黄色荧光蛋白标记轴突，结果显示，在器官型切片培养中，水平轴突形成多个分支。这种分支的形成是相当大的增加，通过引入组成型活性RhoA和显性负RhoA略有抑制。内源性RhoA信号传导的激活剂和抑制剂也分别促进和抑制分支。水平轴突生长的日常成像进一步表明，组成型活性RhoA增加了分支的动态增加和损失。此外，活性RhoA的量相对于RhoA的总量通过下拉测定法在用钠通道或谷氨酸受体阻断剂处理以减少神经活性的皮质切片中进行检查。活动封锁显着降低活性RhoA相比，正常的文化条件下，其中自发放电是突出的。这些发现表明，RhoA信号作为一个积极的调节剂的活动依赖性轴突分支在皮层神经元。
During development, axon branching is influenced by sensory-evoked and spontaneous neural activity. We studied the molecular mechanism that underlies activity-dependent branch formation at horizontally elongating axons ( horizontal axons) in the upper cortical layers, focusing on Rho family small GTPases. Axonal labeling with enhanced yellow fluorescent protein showed that horizontal axons formed several branches in organotypic slice cultures. This branch formation was considerably increased by introducing constitutively active RhoA and was slightly inhibited by dominant-negative RhoA. Activators and inhibitors of endogenous RhoA signaling also promoted and inhibited branching, respectively. Daily imaging of horizontal axon growth further demonstrated that constitutively active RhoA increased the dynamic addition and loss of branches. Moreover, the amount of active RhoA relative to the total amount of RhoA was examined by a pull-down assay in cortical slices treated with sodium channel or glutamate receptor blockers to reduce neural activity. Activity blockade significantly decreased active RhoA compared with normal culture conditions, in which spontaneous firing is prominent. These findings suggest that RhoA signaling acts as a positive regulator for activity-dependent axon branching in cortical neurons.