Focal adhesion kinase acts downstream of EphB receptors to maintain mature dendritic spines by regulating cofilin activity.
Focal adhesion kinase acts downstream of EphB receptors to maintain mature dendritic spines by regulating cofilin activity.
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DOI：
10.1523/jneurosci.4681-08.2009
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发表时间：
2009-06-24
期刊：
影响因子：
--
通讯作者：
Ethell IM
中科院分区：
文献类型：
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作者：
Shi Y;Pontrello CG;DeFea KA;Reichardt LF;Ethell IM
树突棘是大脑中大多数兴奋性突触的突触后位点，富含聚合的 F-肌动蛋白，可驱动成熟树突棘和突触的形成和维持。我们提出，抑制肌动蛋白切断蛋白丝切蛋白的活性在成熟树突棘的稳定中发挥着重要作用，并且是通过EphB受体-粘着斑激酶（FAK）途径来实现的。我们的研究表明，在原代海马培养物中，Cre 介导的 loxP 侧翼 fak 敲除促使成熟树突棘恢复为未成熟的丝状伪足样表型。 FAK 缺失对树突棘数量、长度和形态的影响通过组成型活性 FAKY397E（而非 FAKY397F）的过度表达得以挽救，这表明通过酪氨酸 397 磷酸化激活 FAK 的重要性。我们的研究表明，FAK 作用于海马神经元中 EphB 受体和 EphB2-FAK 信号传导的下游 通过促进丝切蛋白磷酸化来控制成熟树突棘的稳定性，从而抑制丝切蛋白活性。虽然组成型活性非磷酸化 cofilinS3A 诱导了不成熟的脊柱轮廓，但拟磷酸化 cofilinS3D 恢复了 EphB 活性破坏或缺乏 FAK 的神经元的成熟脊柱形态。此外，我们发现 EphB 介导的丝切蛋白活性调节至少部分依赖于 Rho 相关激酶 (ROCK) 和 LIMK-1 的激活。这些发现表明，EphB2 介导的树突棘稳定部分依赖于 FAK 激活 RhoA-ROCK-LIMK-1 途径的能力，该途径的作用是抑制丝切蛋白活性并抑制丝切蛋白介导的树突棘重塑。
Dendritic spines are the postsynaptic sites of most excitatory synapses in the brain and are highly enriched in polymerized F-actin, which drives the formation and maintenance of mature dendritic spines and synapses. We propose that suppressing the activity of the actin-severing protein cofilin plays an important role in the stabilization of mature dendritic spines, and is accomplished through an EphB receptor–focal adhesion kinase (FAK) pathway. Our studies revealed that Cre-mediated knock-out of loxP-flanked fak prompted the reversion of mature dendritic spines to an immature filopodial-like phenotype in primary hippocampal cultures. The effects of FAK depletion on dendritic spine number, length, and morphology were rescued by the overexpression of the constitutively active FAKY397E, but not FAKY397F, indicating the significance of FAK activation by phosphorylation on tyrosine 397. Our studies demonstrate that FAK acts downstream of EphB receptors in hippocampal neurons and EphB2–FAK signaling controls the stability of mature dendritic spines by promoting cofilin phosphorylation, thereby inhibiting cofilin activity. While constitutively active nonphosphorylatable cofilinS3A induced an immature spine profile, phosphomimetic cofilinS3D restored mature spine morphology in neurons with disrupted EphB activity or lacking FAK. Further, we found that EphB-mediated regulation of cofilin activity at least partially depends on the activation of Rho-associated kinase (ROCK) and LIMK-1. These findings indicate that EphB2-mediated dendritic spine stabilization relies, in part, on the ability of FAK to activate the RhoA–ROCK–LIMK-1 pathway, which functions to suppress cofilin activity and inhibit cofilin-mediated dendritic spine remodeling.