Functional and selective RNA interference in developing axons and growth cones
Functional and selective RNA interference in developing axons and growth cones
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DOI：
10.1523/jneurosci.5229-05.2006
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发表时间：
2006-05-24
影响因子：
5.3
通讯作者：
Jaffrey, Samie R.
中科院分区：
文献类型：
--
作者：
Hengst, Ulrich;Cox, Llewellyn J.;Jaffrey, Samie R.
发育中的轴突和生长锥含有“局部”mRNA，其响应于各种细胞外信号分子而被翻译，并且在轴突发育期间的几个过程中发挥作用，包括轴突寻路、轴突在趋化梯度中的定向以及调节神经递质释放。调节轴突和生长锥内mRNA翻译的分子机制尚不清楚。在这里，我们表明，参与RNA干扰（RNAi）的蛋白质，包括argonaute-3和argonaute-4，切丁酶，和脆性X智力低下蛋白，被发现在发展中的轴突和生长锥。这些蛋白质组装成功能性RNA诱导的沉默复合物，因为小干扰RNA选择性地转染到远端轴突中导致远端轴突特异性mRNA敲低，而不降低近端轴突中的转录物水平或小干扰RNA向近端轴突或细胞体中的相关扩散。RhoA mRNA定位于轴突和生长锥，并且RhoA的轴突内翻译是由脑信号蛋白3A（Sema 3A）（一种轴突引导因子）引起的生长锥塌陷所必需的。轴突RhoA mRNA的选择性敲低废除了Sema 3A依赖的生长锥塌陷。我们的研究结果表明，功能和有效的RNAi在轴突和确定一种方法来空间调节mRNA转录在神经元的亚细胞水平。
Developing axons and growth cones contain "local" mRNAs that are translated in response to various extracellular signaling molecules and have roles in several processes during axonal development, including axonal pathfinding, orientation of axons in chemotactic gradients, and in the regulation of neurotransmitter release. The molecular mechanisms that regulate mRNA translation within axons and growth cones are unknown. Here we show that proteins involved in RNA interference (RNAi), including argonaute-3 and argonaute-4, Dicer, and the fragile X mental retardation protein, are found in developing axons and growth cones. These proteins assemble into functional RNA-induced silencing complexes as transfection of small interfering RNAs selectively into distal axons results in distal axon-specific mRNA knock-down, without reducing transcript levels in proximal axons or associated diffusion of small interfering RNA into proximal axons or cell bodies. RhoA mRNA is localized to axons and growth cones, and intra-axonal translation of RhoA is required for growth cone collapse elicited by Semaphorin 3A (Sema3A), an axonal guidance cue. Selective knock-down of axonal RhoA mRNA abolishes Sema3A-dependent growth cone collapse. Our results demonstrate functional and potent RNAi in axons and identify an approach to spatially regulate mRNA transcripts at a subcellular level in neurons.