Dynamic analysis of subcellular ionic signalling in neurons

我们通过比较野生型和突变型功能分子或小鼠品系，研究了中枢神经元局部离子信号的动态方面。更准确地说，我们研究了电压门控钙通道和受体激活的钙渗透阳离子通道的分子生物学和电生理学分析。阐明了钙通道突变导致小脑性共济失调发病机制的几个步骤。此外，我们发现受体激活的钙渗透通道在包括大脑在内的广泛组织中表达，并在细胞调节的各个方面发挥重要作用。为了揭示6型脊髓小脑性共济失调的致病机制，我们在重组表达系统中分析了P/ q型钙通道CAG核苷酸重复延伸的功能特性，以获得电压依赖性失活的负移。这一变化更符合钙流入减少可能导致小脑神经元紊乱的观点。我们鉴定了突变型共济失调小鼠滚动名古屋的钙通道α1A基因突变。突变位于电压感应区。事实上，钙离子通道除了降低电流幅度外，还显示出降低的电压敏感性。这项研究显示了单个突变如何导致神经元回路的异常发育和功能。TRP通道是受体激活通道的代表。我们对TRP通道家族的成员进行了分子分析。利用重组表达系统表征了TRP通道的功能特性。特别是，TRP7在没有外界刺激的情况下被组成性激活，其功能与之前确定的钙渗透性非选择性阳离子通道相似。TRP通道家族的成员可能参与神经元在接受重复刺激时的持续去极化。少

We investigated dynamic aspect of local ionic signaling en central neurons, by comparing wild-type and mutant functional molecules or mouse strains. More precisely, we studied molecular biological and electrophysilogical analyses of voltage-gated calcium channels and receptor-activated calcium permeable cation channels. We clarified some steps of the pathogenic mechanism how the calcium channel mutations lead to cerebellar ataxia. Also we showed that receptor-activated calcium permeable channels are expressed in a wide range of tissues including brain, and are critically involved in various aspects of cell regulation.To uncover the pathogenic mechanism of human spinocerebellar ataxia type 6, which has been shown to be associated with CAG nucleotide repeat extension in the P/Q-type calcium channel, we analyzed functional properties of the calcium channel with the extension in a recombinant expression system, to obtain the negative shift of voltage-dependent inactivation. This change is … More consistent with the idea that reduced calcium influx can be a cause of the cerebellar neuronal disorder.We identified the mutation in the calcium channel α1A gene of the mutant ataxic mouse rolling nagoya. The mutation was located in the voltage sensing region. In fact, the calcium channel was shown to have a reduced voltage sensitivity in addition to reduced current amplitude. This study showed how a single mutation leads to abnormal development and function of the neuronal circuit.The TRP channel is a representative of receptor-activated channels. We conducted molecular analyses of the members of the TRP channel family. The functional properties of TRP channels are characterized using recombinant expression systems. In particular, TRP7, which is constitutively activated without external stimulation, was shown to be functionally similar to the channel previously identified as a calcium permeable non-selective cation channel. The members of TRP channel family may contribute to sustained depolarization of neurons when then receive repetitive stimulations. Less