Compartmentalization of the MAPK scaffold protein KSR1 modulates synaptic plasticity in hippocampal neurons
Compartmentalization of the MAPK scaffold protein KSR1 modulates synaptic plasticity in hippocampal neurons
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DOI：
10.1096/fj.10-173153
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发表时间：
2011-07-01
期刊：
影响因子：
4.8
通讯作者：
Mueller, Juergen
中科院分区：
文献类型：
--
作者：
Canal, Frederic;Palygin, Oleg;Mueller, Juergen
ERK 1/2是某些形式的突触可塑性所必需的，包括突触强度的长时程增强。然而，调节突触定位的ERK 1/2信号转导的分子机制知之甚少。在这里，我们表明，MAPK支架蛋白激酶抑制因子Ras 1（KSR 1）是直接磷酸化的下游激酶ERK 1/2。定量蛋白质印迹分析进一步证明，突变的，反馈缺陷型KSR1的表达促进持续的ERK 1/2在HEK293细胞中的激活响应于EGF刺激，相比之下，在表达野生型KSR1的对照细胞中的更短暂的激活。新生C57BL6小鼠原代海马神经元的免疫细胞化学和共聚焦成像进一步表明，KSR 1的反馈磷酸化显著降低了其在树突棘上的定位。这种作用可以逆转河豚毒素（1 μ M）或PD184352（2 μ M）的治疗，进一步表明，神经元的活动和磷酸化的ERK 1/2导致KSR 1从突触后室。因此，表达野生型或反馈缺陷型KSR1的海马神经元的电生理记录表明，KSR1反馈磷酸化限制了兴奋性突触后电流的增强。因此，我们的研究结果表明，支架蛋白KSR 1的反馈磷酸化可以防止突触后区室中过度的ERK 1/2信号传导，从而有助于维持突触兴奋性的生理水平。Canal，F.，帕雷金岛，Pankratov，Y.，Correa，S. a. L.，Muller，J. MAPK支架蛋白KSR 1的区室化调节海马神经元的突触可塑性。FASEB J.25，2362 - 2372（2011）。www.fasebj.org
ERK1/2 is required for certain forms of synaptic plasticity, including the long-term potentiation of synaptic strength. However, the molecular mechanisms regulating synaptically localized ERK1/2 signaling are poorly understood. Here, we show that the MAPK scaffold protein kinase suppressor of Ras 1 (KSR1) is directly phosphorylated by the downstream kinase ERK1/2. Quantitative Western blot analysis further demonstrates that expression of mutated, feedback-deficient KSR1 promotes sustained ERK1/2 activation in HEK293 cells in response to EGF stimulation, compared to a more transient activation in control cells expressing wild-type KSR1. Immunocytochemistry and confocal imaging of primary hippocampal neurons from newborn C57BL6 mice further show that feedback phosphorylation of KSR1 significantly reduces its localization to dendritic spines. This effect can be reversed by tetrodotoxin (1 mu M) or PD184352 (2 mu M) treatment, further suggesting that neuronal activity and phosphorylation by ERK1/2 lead to KSR1 removal from the postsynaptic compartment. Consequently, electrophysiological recordings in hippocampal neurons expressing wild-type or feedback-deficient KSR1 demonstrate that KSR1 feedback phosphorylation restricts the potentiation of excitatory postsynaptic currents. Our findings, therefore, suggest that feedback phosphorylation of the scaffold protein KSR1 prevents excessive ERK1/2 signaling in the postsynaptic compartment and thus contributes to maintaining physiological levels of synaptic excitability.-Canal, F., Palygin, O., Pankratov, Y., Correa, S. A. L., Muller, J. Compartmentalization of the MAPK scaffold protein KSR1 modulates synaptic plasticity in hippocampal neurons. FASEB J. 25, 2362-2372 (2011). www.fasebj.org