Functional interaction between BDNF and mGluR II in vitro: BDNF down-regulated mGluR II gene expression and an mGluR II agonist enhanced BDNF-induced BDNF gene expression in rat cerebral cortical neurons
Functional interaction between BDNF and mGluR II in vitro: BDNF down-regulated mGluR II gene expression and an mGluR II agonist enhanced BDNF-induced BDNF gene expression in rat cerebral cortical neurons
复制标题
DOI：
10.1016/j.peptides.2017.01.007
复制
发表时间：
2017-03-01
期刊：
影响因子：
3
通讯作者：
Miki, Takanori
中科院分区：
文献类型：
--
作者：
Suzuki, Shingo;Koshimizu, Hisatsugu;Miki, Takanori
越来越多的证据表明，脑源性神经营养因子(BDNF)和代谢性谷氨酸受体(MGluR)信号通路在中枢神经系统(CNS)中存在功能上的相互作用。到目前为止，已鉴定出mGluR的八种亚型，即mGluR1-8，先前的研究表明，BDNF导致大鼠大脑皮层培养的GIuR2基因表达下调。然而，BDNF对其他mGluR的精确转录作用及其在BDNF信号通路中的细胞意义仍很大程度上是未知的。在这项研究中，我们研究了脑源性神经营养因子对原代培养的大鼠大脑皮层神经元mGluR1-8转录的影响，以及受脑源性神经营养因子调控的mGluR(S)对脑源性神经营养因子靶基因转录的影响。实时定量聚合酶链式反应(RT-qPCR)显示，100 ng/mLBDNF刺激后，mGluR2和mGluR3的基因表达水平均显著降低，两者均属于组II mGluR(MGluR II)。而mGluRI(mGluK1和mGluk5)和mGluR4、6、7和8(mGluR4、6、7和8)则无明显变化。此外，10 ng/mLBDNF主要激活高亲和力BDNF受体TrkB，而不激活低亲和力受体p75(NTR)，可诱导mGluR II mRNA下调。电压门控性钠通道阻断剂河豚毒素(TTX)不能显著减弱BDNF对mGluR II的抑制作用。此外，在BDNF(100 ng/mL)刺激下，仅表达TrkB截短型的培养星形胶质细胞mGluR II mRNA表达没有明显下调。最后，我们评估了mGluR II对BDNF靶基因、BDNF和活性调节细胞骨架相关蛋白(Arc)表达的影响。MGluR II激动剂LY404039可增强BDNF诱导的BDNF上调，但对Arc无明显作用。另一方面，mGluR II拮抗剂LY341495下调BDNF的mRNA水平。总之，这些观察结果证明了BDNF和mGluR II之间详细的功能相互作用：激活mGluR II正向调节自身诱导的BDNF表达，反过来，BDNF以神经元活动非依赖性的方式负向调节mGluR II的基因表达，在皮质神经元中，而在星形胶质细胞中。(C)2017 Elsevier Inc.保留所有权利。
Accumulating evidence suggests functional interaction between brain-derived neurotrophic factor (BDNF) and metabotropic glutamate receptor (mGluR) signaling pathways in the central nervous system (CNS). To date, eight subtypes of mGluRs, mGluR1-8, have been identified, and a previous study suggested that BDNF leads to down-regulation of GIuR2 mRNA in rat cerebral cortical cultures. However, precise transcriptomic effects of BDNF on other mGluRs and their cellular significance on the BDNF signaling pathway remain largely unknown. In this study, we assessed the transcriptomic effects of BDNF on mGluR1-8 in primary cultures of rat cerebral cortical neurons, and transcriptomic impacts of mGluR(s) whose expression is regulated by BDNF, on BDNF target genes. Real-time quantitative PCR (RT-qPCR) revealed that stimulation of the cultures with 100 ng/mL BDNF led to marked reductions not only in the gene expression levels of mGluR2, but also in those of mGluR3, both of which belong to group II mGluRs (mGluR II). There were, on the other hand, no changes in the amounts of mGluR I (mGluk1 and 5) and III (mGluR4, 6, 7, and 8) mRNA. Further, 10 ng/mL of BDNF, which mainly activates the high-affinity BDNF receptor, TrkB, but not the low-affinity receptor, p75(NTR), was able to induce down-regulation of mGluR II mRNA. The BDNF-induced suppression of mGluR II was not significantly attenuated in the presence of tetrodotoxin (TTX), a blocker for voltage-gated sodium channels. In addition, on stimulation with BDNF (100 ng/mL), no significant down-regulation of mGluR II mRNA was seen in cultured astrocytes, which only express the truncated form of TrkB. Finally, we assessed the transcriptomic effect of mGluR II on the expressions of BDNF target genes, BDNF and activity-regulated cytoskeleton-associated protein (Arc). LY404039, an mGluR II agonist, enhanced the BDNF-induced up-regulation of BDNF, but not Arc. On the other hand, LY341495, an mGluR II antagonist, down-regulated BDNF mRNA levels. Collectively, these observations demonstrated the detailed functional interaction between BDNF and mGluR II: Activation of mGluR II positively regulates self-induced BDNF expression, and, in turn, BDNF negatively regulates the gene expression of mGluR II in a neuronal activity-independent manner, in cortical neurons, but not in astrocytes. (C) 2017 Elsevier Inc. All rights reserved.