Slit and Netrin-1 guide cranial motor axon pathfinding via Rho-kinase, myosin light chain kinase and myosin II.
Slit and Netrin-1 guide cranial motor axon pathfinding via Rho-kinase, myosin light chain kinase and myosin II.
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DOI：
10.1186/1749-8104-5-16
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发表时间：
2010-06-22
影响因子：
3.6
通讯作者：
Guthrie S
中科院分区：
文献类型：
--
作者：
Murray A;Naeem A;Barnes SH;Drescher U;Guthrie S
在发育中的后脑中，颅运动轴突的引导取决于底板产生的扩散排斥因子。我们之前的研究表明介导这种效应的候选分子是 Slits、Netrin-1 和 Semaphorin3A (Sema3A)。目前尚不清楚这些因素在多大程度上对运动轴突的底板衍生化学排斥起作用，并且下游信号传导途径在很大程度上尚不清楚。在这项研究中，我们结合使用体外和体内方法来鉴定底板化学排斥的成分及其下游信号通路。使用体外运动轴突偏转测定，我们证明了 Slits 和 Netrin-1，而不是 Sema3A，有助于底板排斥。我们还发现，在 Netrin-1 突变小鼠和表达显性失活 Unc5a 受体的鸡胚胎中，背侧突出的鳃运动神经元的轴突通路被破坏，表明 Netrin-1 的体内作用。我们进一步证明，Slit 和 Netrin-1 信号传导是由 Rho 激酶 (ROCK) 和肌球蛋白轻链激酶 (MLCK) 介导的，它们调节肌球蛋白 II 活性，控制生长锥中的肌动蛋白逆行流动。我们发现 MLCK、ROCK 和肌球蛋白 II 是 Slit 和 Netrin-1 介导的颅运动轴突生长锥塌陷所必需的。在外植体培养物中抑制这些分子，或在体内对 RhoA 或肌球蛋白 II 功能进行基因操作会导致特征性颅运动轴突寻路错误，包括无法退出中线以及无法转向退出点。我们的研究结果表明，Slits 和 Netrin-1 都有助于颅运动轴突的底板衍生化学排斥。他们进一步表明，RhoA/ROCK、MLCK 和肌球蛋白 II 是 Slit 和 Netrin-1 信号通路的组成部分，并表明这些通路在颅运动轴突导航中至关重要。
In the developing hindbrain, cranial motor axon guidance depends on diffusible repellent factors produced by the floor plate. Our previous studies have suggested that candidate molecules for mediating this effect are Slits, Netrin-1 and Semaphorin3A (Sema3A). It is unknown to what extent these factors contribute to floor plate-derived chemorepulsion of motor axons, and the downstream signalling pathways are largely unclear. In this study, we have used a combination of in vitro and in vivo approaches to identify the components of floor plate chemorepulsion and their downstream signalling pathways. Using in vitro motor axon deflection assays, we demonstrate that Slits and Netrin-1, but not Sema3A, contribute to floor plate repulsion. We also find that the axon pathways of dorsally projecting branchiomotor neurons are disrupted in Netrin-1 mutant mice and in chick embryos expressing dominant-negative Unc5a receptors, indicating an in vivo role for Netrin-1. We further demonstrate that Slit and Netrin-1 signalling are mediated by Rho-kinase (ROCK) and myosin light chain kinase (MLCK), which regulate myosin II activity, controlling actin retrograde flow in the growth cone. We show that MLCK, ROCK and myosin II are required for Slit and Netrin-1-mediated growth cone collapse of cranial motor axons. Inhibition of these molecules in explant cultures, or genetic manipulation of RhoA or myosin II function in vivo causes characteristic cranial motor axon pathfinding errors, including the inability to exit the midline, and loss of turning towards exit points. Our findings suggest that both Slits and Netrin-1 contribute to floor plate-derived chemorepulsion of cranial motor axons. They further indicate that RhoA/ROCK, MLCK and myosin II are components of Slit and Netrin-1 signalling pathways, and suggest that these pathways are of key importance in cranial motor axon navigation.
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影响因子：
64.5
作者：
Brose, K;Bland, KS;Kidd, T
通讯作者：
Kidd, T
影响因子：
4.6
作者：
Anderson, CNG;Ohta, K;Tannahill, D
通讯作者：
Tannahill, D
影响因子：
2.7
作者：
Kim, YS;Fritz, JL;VanBerkum, MFA
通讯作者：
VanBerkum, MFA
影响因子：
4.6
作者：
Hammond, R;Vivancos, V;Guthrie, S
通讯作者：
Guthrie, S
影响因子：
3.4
作者：
CHEDOTAL, A;POURQUIE, O;SOTELO, C
通讯作者：
SOTELO, C