Yamada Ryuji X, Sasaki Takuya, Ichikawa Junya, Koyama Ryuta, Matsuki Norio, Ikegaya Yuji
Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan.
J Neurosci. 2008 Apr 30;28(18):4613-8. doi: 10.1523/JNEUROSCI.0019-08.2008.
Axon guidance molecules trigger a cascade of local signal in growth cones and evoke various morphologic responses, including axon attraction, repulsion, elongation, and retraction. However, little is known about whether subcellular compartments, other than axonal growth cones, control axon outgrowth. We found that in isolated dentate granule cells, local application of glutamate to the somatodendritic areas, but not the axon itself, induced rapid axon retraction, during which a calcium wave propagated from the somata to the axon terminals. The calcium wave and axon retraction were both inhibited by blockade of voltage-sensitive calcium channels and intracellular calcium dynamics. A combination of perisomatic application of calcium ionophore and depolarizing current injection induced axonal calcium sweep and axon retraction. Thus, perisomatic environments can modulate axon behavior through long-range intracellular communication.
轴突导向分子在生长锥中引发一系列局部信号，并引发各种形态学反应，包括轴突吸引、排斥、伸长和回缩。然而，除轴突生长锥外，亚细胞区室是否控制轴突生长，目前知之甚少。我们发现，在分离的齿状颗粒细胞中，向树突体区域而非轴突本身局部施加谷氨酸会诱导轴突快速回缩，在此过程中钙波从胞体传播到轴突末端。电压敏感性钙通道的阻断和细胞内钙动力学均抑制了钙波和轴突回缩。胞体周围应用钙离子载体和去极化电流注射相结合可诱导轴突钙扫描和轴突回缩。因此，胞体周围环境可通过远程细胞内通讯调节轴突行为。
