Erythropoietin receptor-mediated inhibition of exocytotic glutamate release confers neuroprotection during chemical ischemia
Erythropoietin receptor-mediated inhibition of exocytotic glutamate release confers neuroprotection during chemical ischemia
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DOI：
10.1074/jbc.m105832200
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发表时间：
2001-10-19
影响因子：
4.8
通讯作者：
Takahashi, M
中科院分区：
文献类型：
--
作者：
Kawakami, M;Sekiguchi, M;Takahashi, M
促红细胞生成素（EPO）减少Ca2+诱导的谷氨酸（Glu）释放培养的小脑颗粒神经元。EPO模拟肽1 （EPO受体的一种小合成肽激动剂，EPO- r）也能产生抑制作用，但ep1的一种无活性类似物iEMP1不能。EPO和EMP1诱导Janus kinase 2 （JAK2）的自磷酸化，JAK2是一种与EPO- r相关的酪氨酸激酶。此外，染料木素可以拮抗JAK2的磷酸化，并抑制EPO和EMP1诱导的Glu释放。在化学缺血期间，培养的小脑和海马神经元通过至少两种不同的机制释放大量的谷氨酸。在早期，Glu通过突触囊泡内容物的胞吐释放，因为它被B型肉毒杆菌神经毒素（BoNT/B）所消除。相反，Glu释放的后期主要涉及BoNT/ b不敏感的非胞外途径。EMP1仅在胞吐早期抑制Glu的释放。海马切片暴露于化学缺血20分钟后，可诱导神经元细胞死亡，特别是CA1区和齿状回的神经元细胞死亡可被EMP1而非iEMP1抑制。然而，EMP1并不能减轻外源性Glu诱导的神经元细胞死亡。这些结果表明，EPO-R的激活通过抑制Glu的胞吐来抑制缺血细胞死亡。
Erythropoietin (EPO) reduced Ca2+-induced glutamate (Glu) release from cultured cerebellar granule neurons. Inhibition was also produced by EPO mimetic peptide 1 (EMP1), a small synthetic peptide agonist of EPO receptor (EPO-R), but not by iEMP1, an inactive analogue of EMP1. EPO and EMP1 induced autophosphorylation of Janus kinase 2 (JAK2), a tyrosine kinase that associates with EPO-R. Furthermore, genistein, but not genistin, antagonized both the phosphorylation of JAK2 and the suppression of Glu release induced by EPO and EMP1. During chemical ischemia, substantial amounts of Glu were released from cultured cerebellar and hippocampal neurons by at least two distinct mechanisms. In the early phase, Glu release occurred by exocytosis of synaptic vesicle contents, because it was abolished by botulinum type B neurotoxin (BoNT/B). In contrast, the later phase of Glu release mainly involved a BoNT/B-insensitive non-exocytotic pathway. EMP1 inhibited Glu release only during the early exocytotic phase. A 20-min exposure of hippocampal slices to chemical ischemia induced neuronal cell death, especially in the CA1 region and the dentate gyrus, which was suppressed by EMP1 but not iEMP1. However, EMP1 did not attenuate neuronal cell death induced by exogenously applied Glu. These results suggest that activation of EPO-R suppresses ischemic cell death by inhibiting the exocytosis of Glu.