Neuronal filopodium formation induced by the membrane glycoprotein M6a (Gpm6a) is facilitated by coronin-1a, Rac1, and p21-activated kinase 1 (Pak1)
Neuronal filopodium formation induced by the membrane glycoprotein M6a (Gpm6a) is facilitated by coronin-1a, Rac1, and p21-activated kinase 1 (Pak1)
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DOI：
10.1111/jnc.13552
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发表时间：
2016-04-01
影响因子：
4.7
通讯作者：
Fuchsova, Beata
中科院分区：
文献类型：
--
作者：
Alvarez Julia, Anabel;Frasch, Alberto C.;Fuchsova, Beata
应激反应性神经元膜糖蛋白M6 a（Gpm 6a）在神经突延伸、丝状伪足和棘形成以及突触发生中起作用。Gpm 6a在这些过程中的作用机制尚不完全清楚。以前，我们确定了肌动蛋白调节冠蛋白-1a（Coro 1a）作为一个假定的Gpm 6a相互作用的合作伙伴。在这里，我们使用抗Coro 1a抗体的免疫共沉淀试验表明，Coro 1a与大鼠海马神经元中的Gpm 6a相关。通过免疫荧光显微镜，我们证明，在海马神经元Coro 1a定位在F-肌动蛋白富集区和一些Coro 1a斑点共定位与Gpm 6a标记。值得注意的是，Coro 1a的显性负性形式的过表达以及siRNA对其的下调干扰了Gpm 6a诱导的丝状伪足形成。已知Coro 1a可调节质膜转位和小GTTR Rac 1的激活。我们发现，Coro 1a与Rac 1和Gpm 6a共同免疫沉淀。Rac 1的药理学抑制导致Gpm 6a的丝状伪足形成显著减少。在Gpm 6a与无活性GDP结合形式的Rac 1共表达时也观察到相同的结果。在这种情况下，也检测到GDP结合的Rac 1的膜募集增加。此外，p21激活的激酶1（Pak 1），一个主要的下游效应Rac 1的下游Coro 1a的行为，需要Gpm 6a诱导的丝状伪足形成的激酶活性。总之，我们的研究结果提供了证据，包括Coro 1a，Rac 1和Pak 1的信号通路促进Gpm 6a诱导的丝状伪足形成。
Stress-responsive neuronal membrane glycoprotein M6a (Gpm6a) functions in neurite extension, filopodium and spine formation and synaptogenesis. The mechanisms of Gpm6a action in these processes are incompletely understood. Previously, we identified the actin regulator coronin-1a (Coro1a) as a putative Gpm6a interacting partner. Here, we used co-immunoprecipitation assays with the anti-Coro1a antibody to show that Coro1a associates with Gpm6a in rat hippocampal neurons. By immunofluorescence microscopy, we demonstrated that in hippocampal neurons Coro1a localizes in F-actin-enriched regions and some of Coro1a spots co-localize with Gpm6a labeling. Notably, the over-expression of a dominant-negative form of Coro1a as well as its down-regulation by siRNA interfered with Gpm6a-induced filopodium formation. Coro1a is known to regulate the plasma membrane translocation and activation of small GTPase Rac1. We show that Coro1a co-immunoprecipitates with Rac1 together with Gpm6a. Pharmacological inhibition of Rac1 resulted in a significant decrease in filopodium formation by Gpm6a. The same was observed upon the co-expression of Gpm6a with the inactive GDP-bound form of Rac1. In this case, the elevated membrane recruitment of GDP-bound Rac1 was detected as well. Moreover, the kinase activity of the p21-activated kinase 1 (Pak1), a main downstream effector of Rac1 that acts downstream of Coro1a, was required for Gpm6a-induced filopodium formation. Taken together, our results provide evidence that a signaling pathway including Coro1a, Rac1, and Pak1 facilitates Gpm6a-induced filopodium formation.