Identification of signal transduction cascades involved in long-lasting potentiation of inhibitory synapses

鉴定参与抑制性突触持久增强的信号转导级联

• 批准号: 05454677
• 负责人: KANO Masanobu
• 金额: $ 4.54万
• 依托单位: Jichi Medical School
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05454677/
• 关键词: cerebellar slice; patch clamp; inhibitory synapse; long-lasting potentiation; GABA receptor; Ca^<2+>; calmodulin-dependent kinase II; protein phosphatase; protein kinase G; protein kinase C; 遺伝子ノックアオウトマウス; calmodulin-dependent protein kinase II

In cerebellar Purkinje cells, GABAergic inhibitory synaptic transmission undergoes long-lasting "rebound potentiation" following activation of excitatory climbing fiber iputs. Rebound potentiation is triggered by a climbing fiber-induced transient elevation of intracellular Ca^<2+> concentration, and is expressed as a long-lasting increase of postsynaptic GABA_A receptor sensitivity. In the present series of study, I found that inhibitors of the Ca^<2+>/calmodulin-dependent kinase II (CaM-KII) signal transduction pathway effectively block the induction of rebound potentiation. A non-selective protein kinase inhibitor, staurosporine, effectively blocked the induction of rebound potentiation. A calmodulin antagonist, calmidazolium, and a CaM-KII antagonist, KN-62, effectively blocked rebound potentiation, when they were applied extracellularly prior to and during Ca^<2+> channel activation. On the other hand, these antagonists had no effects on the once established rebound potentiation. … More Intracellular application of a peptide antagonist of CaM-KII also blocked the induction of rebound potentiation. These inhibitors had no effects on voltage-gated Ca^<2+> channel currents or on the basal inhibitory transmission itself. Furthermore, intracellular injection of active CaM-KII and application of a phosphatase inhibitor, calyculin A,induced enhancement of GABA_A receptor-mediated currents. These results strongly suggest that RP involves CaM-KII-mediated protein phosphorylation. The functional state of GABA_A receptors may be dependent on the balance between the phosphorylation by CaM-KII and the dephosphorylation by protein phosphatases.I did not obtain the results that support involvement of other protein kinase cascades in rebound potentiation. As far as I examined, inhibitors of protein kinase A,protein kinase C and protein kinase G had no significant effects on rebound potentiation. The issues of involvement of these protein kinase cascades will be further studied using gene knockout mice. Less

在小脑浦肯野细胞，GABA能抑制性突触传递在兴奋性攀爬纤维输入激活后经历了持久的“反弹增强”。反弹增强是由攀爬纤维引起的细胞内Ca^2+浓度的短暂升高触发的，并表现为突触后GABA_A受体敏感性的持久增加。在本系列研究中，我发现Ca^<2+>/钙调蛋白依赖性激酶II（CaM-KII）信号传导途径的抑制剂有效地阻断了反弹增强的诱导。一种非选择性蛋白激酶抑制剂，星形孢菌素，有效地阻止了诱导反弹增强。钙调素拮抗剂calmidazolium和CaM-KII拮抗剂KN-62在Ca^2+通道激活前和激活过程中细胞外应用时，可有效阻断反跳增强。另一方面，这些拮抗剂对一旦建立的反弹增强没有影响。 ...更多信息 细胞内应用的肽拮抗剂的CaM-KII也阻止了诱导反弹增强。这些抑制剂对电压门控Ca^2+通道电流或基础抑制传递本身没有影响。此外，细胞内注射活性CaM-KII和应用磷酸酶抑制剂calyculin A，诱导GABA_A受体介导的电流增强。这些结果强烈表明，RP涉及CaM-KII介导的蛋白磷酸化。GABA_A受体的功能状态可能依赖于CaM-KII磷酸化和蛋白磷酸酶去磷酸化之间的平衡，我没有得到支持其他蛋白激酶级联参与反弹增强的结果。据我所知，蛋白激酶A、蛋白激酶C和蛋白激酶G的抑制剂对反跳增强没有显著影响。这些蛋白激酶级联的参与问题将进一步研究使用基因敲除小鼠。少

项目成果

M.Kano,et al.: "Impaired synapse elimination dueing cerebellar development in PKCγ mutant mice." Cell. 83. 1223-1231 (1995)

M.Kano 等人：“由于 PKCγ 突变小鼠的小脑发育而导致突触消除受损。”Cell 83. 1223-1231 (1995)

狩野 方伸,川合述史: "グルタミン酸レセプター." Clin.Neurosci.548-553 (1995)

Masanobu Kano，S. Kawai：“谷氨酸受体。”Clin.Neurosci.548-553 (1995)

M,Kano: "Long-lasting rebound potentiation of GABAergic inhibitory synaptic currents in cerebellar Purkinje cells" Biomedical Research. 15,Suppl.1. 62-72 (1994)

M，Kano：“小脑浦肯野细胞中 GABA 能抑制性突触电流的持久反弹增强”生物医学研究。

M,Kano: "Plasticity of inhibitory synapses in the brain:a possible memory mechanism that has been overlooked" Neuroscience Research. 21. 177-182 (1995)

M，卡诺：“大脑中抑制性突触的可塑性：一种可能被忽视的记忆机制”神经科学研究。

狩野 方伸: "佐藤昌康/編、ブレインサイエンス最前線95" 講談社サイエンティフィクス, 12 (1994)

嘉纳雅信：“佐藤雅康/编辑，脑科学前沿 95”讲谈社科学，12（1994）