Sustained activation of ERK signaling in astrocytes is critical for neuronal injury-induced monocyte chemoattractant protein-1 production in rat corticostriatal slice cultures
Sustained activation of ERK signaling in astrocytes is critical for neuronal injury-induced monocyte chemoattractant protein-1 production in rat corticostriatal slice cultures
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DOI：
10.1111/j.1460-9568.2010.07160.x
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发表时间：
2010-04-01
影响因子：
3.4
通讯作者：
Minami, Masabumi
中科院分区：
文献类型：
--
作者：
Katayama, Takahiro;Sakaguchi, Emi;Minami, Masabumi
我们以前证明，N-甲基-D-天冬氨酸（NMDA）治疗（50 μ m，3小时）诱导星形胶质细胞产生单核细胞趋化蛋白-1（MCP-1，CCL 2），CC趋化因子涉及缺血性和兴奋性脑损伤，在大鼠皮质纹状体切片培养。在这项研究中，我们研究了NMDA诱导的MCP-1生产在切片培养的信号机制。结果表明，NMDA诱导的神经元损伤和MCP-1的产生之间存在密切的相关性，并且在NMDA预处理的切片中，神经元细胞已经被消除，NMDA诱导的MCP-1的产生被消除。这些结果共同表明NMDA诱导的神经元损伤导致星形胶质细胞产生MCP-1。细胞外信号调节激酶（ERK）抑制剂U 0126可显著抑制NMDA诱导的MCP-1产生。磷酸化ERK的免疫组化染色显示，短暂的神经元ERK激活最初诱导和消退在30分钟内，持续ERK激活星形胶质细胞。仅在早期阶段（U 0126在NMDA给药后15或30 min被洗脱）用U 0126处理抑制神经元细胞中ERK的早期激活，但不抑制星形胶质细胞中ERK的后期激活。在这种情况下，MCP-1的产生没有受到抑制，这表明神经元ERK的激活对于MCP-1的产生不是必需的。与此相反，延迟应用U 0126在3小时后开始的NMDA处理抑制MCP-1的产生相同的程度时，观察到U 0126从3小时前NMDA管理。这些发现表明，持续激活的ERK信号通路在星形胶质细胞中起着关键作用，神经元损伤诱导的MCP-1的生产。
We previously demonstrated that N-methyl-d-aspartate (NMDA) treatment (50 mu m, 3 h) induced astrocytic production of monocyte chemoattractant protein-1 (MCP-1, CCL2), a CC chemokine implicated in ischemic and excitotoxic brain injury, in rat corticostriatal slice cultures. In this study, we investigated the signaling mechanisms for NMDA-induced MCP-1 production in slice cultures. The results showed a close correlation between NMDA-induced neuronal injury and MCP-1 production, and an abrogation of NMDA-induced MCP-1 production in NMDA-pretreated slices where neuronal cells had been eliminated. These results collectively indicate that NMDA-induced neuronal injury led to astrocytic MCP-1 production. NMDA-induced MCP-1 production was significantly inhibited by U0126, an inhibitor of extracellular signal-regulated kinase (ERK). Immunostaining for phosphorylated ERK revealed that transient neuronal ERK activation was initially induced and subsided within 30 min, followed by sustained ERK activation in astrocytes. Treatment with U0126 during only the early phase (U0126 was washed out at 15 or 30 min after NMDA administration) suppressed early activation of ERK in neuronal cells, but not later activation of ERK in astrocytes. In this case, MCP-1 production was not suppressed, suggesting that activation of neuronal ERK is not necessary for MCP-1 production. In contrast, delayed application of U0126 at 3 h after the beginning of NMDA treatment inhibited MCP-1 production to the same degree as that observed when U0126 was applied from 3 h before NMDA administration. These findings suggest that sustained activation of the ERK signaling pathway in astrocytes plays a key role in neuronal injury-induced MCP-1 production.