Fukuchi Mamoru, Tabuchi Akiko, Kuwana Yuki, Watanabe Shinjiro, Inoue Minami, Takasaki Ichiro, Izumi Hironori, Tanaka Ayumi, Inoue Ran, Mori Hisashi, Komatsu Hidetoshi, Takemori Hiroshi, Okuno Hiroyuki, Bito Haruhiko, Tsuda Masaaki
Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences.
Division of Molecular Genetics Research, Life Science Research Center, and.
J Neurosci. 2015 Apr 8;35(14):5606-24. doi: 10.1523/JNEUROSCI.3650-14.2015.
Although coordinated molecular signaling through excitatory and modulatory neurotransmissions is critical for the induction of immediate early genes (IEGs), which lead to effective changes in synaptic plasticity, the intracellular mechanisms responsible remain obscure. Here we measured the expression of IEGs and used bioluminescence imaging to visualize the expression of Bdnf when GPCRs, major neuromodulator receptors, were stimulated. Stimulation of pituitary adenylate cyclase-activating polypeptide (PACAP)-specific receptor (PAC1), a Gαs/q-protein-coupled GPCR, with PACAP selectively activated the calcineurin (CN) pathway that is controlled by calcium signals evoked via NMDAR. This signaling pathway then induced the expression of Bdnf and CN-dependent IEGs through the nuclear translocation of CREB-regulated transcriptional coactivator 1 (CRTC1). Intracerebroventricular injection of PACAP and intraperitoneal administration of MK801 in mice demonstrated that functional interactions between PAC1 and NMDAR induced the expression of Bdnf in the brain. Coactivation of NMDAR and PAC1 synergistically induced the expression of Bdnf attributable to selective activation of the CN pathway. This CN pathway-controlled expression of Bdnf was also induced by stimulating other Gαs- or Gαq-coupled GPCRs, such as dopamine D1, adrenaline β, CRF, and neurotensin receptors, either with their cognate agonists or by direct stimulation of the protein kinase A (PKA)/PKC pathway with chemical activators. Thus, the GPCR-induced expression of IEGs in coordination with NMDAR might occur via the selective activation of the CN/CRTC1/CREB pathway under simultaneous excitatory and modulatory synaptic transmissions in neurons if either the Gαs/adenylate cyclase/PKA or Gαq/PLC/PKC-mediated pathway is activated.
尽管通过兴奋性和调节性神经传递进行的协调分子信号传导对于诱导即时早期基因（IEGs）至关重要，这些基因会导致突触可塑性发生有效变化，但负责的细胞内机制仍不清楚。在这里，我们测量了IEGs的表达，并使用生物发光成像来观察当主要神经调节受体GPCRs受到刺激时脑源性神经营养因子（Bdnf）的表达。用垂体腺苷酸环化酶激活多肽（PACAP）刺激Gαs/q蛋白偶联的GPCR——PACAP特异性受体（PAC1），可选择性激活由NMDAR诱发的钙信号所控制的钙调神经磷酸酶（CN）途径。然后，该信号通路通过CREB调节的转录共激活因子1（CRTC1）的核转位诱导Bdnf和CN依赖性IEGs的表达。在小鼠中进行脑室内注射PACAP和腹腔注射MK801表明，PAC1和NMDAR之间的功能相互作用诱导了大脑中Bdnf的表达。NMDAR和PAC1的共同激活协同诱导了归因于CN途径选择性激活的Bdnf的表达。通过用其同源激动剂刺激其他Gαs或Gαq偶联的GPCR，如多巴胺D1、肾上腺素β、促肾上腺皮质激素释放因子（CRF）和神经降压素受体，或用化学激活剂直接刺激蛋白激酶A（PKA）/蛋白激酶C（PKC）途径，也可诱导这种由CN途径控制的Bdnf表达。因此，如果Gαs/腺苷酸环化酶/PKA或Gαq/磷脂酶C（PLC）/PKC介导的途径被激活，在神经元同时进行兴奋性和调节性突触传递的情况下，GPCR诱导的IEGs与NMDAR协同表达可能通过CN/CRTC1/CREB途径的选择性激活而发生。
