Studies on Rho-and Ca^<2+>-dependent signaling mechanisms regulating neuronal actin cytoskeleton

1.我们研究了Rho下游可能参与调节原代培养小脑颗粒神经元轴突发生的信号通路。之所以选择这些神经元，是因为这些神经元具有有趣的特性，即在电镀后立即产生两个双极轴突，然后再进一步发育神经突起，从而极大地促进了信号分析。我们阐明了SDF-1α/Rho/mDial通路在控制轴突延长速率中的重要积极作用。正如我们以前发现的Rho/ROCK级联的负调控作用一样，我们的数据表明，适当的轴突发生速度可能受到两个不同的Rho效应器ROCK和mDia1.2之间的拮抗作用的严格控制。我们先前描述了突触活动如何诱导海马锥体神经元中的钙动员触发脊椎肌动蛋白的募集。然而，将钙与局部肌动蛋白重组联系起来的关键分子仍然不清楚。我们在这里研究一种新的CaMK，我们鉴定为Click-III/CaMKIγ是否有可能填补这一角色。当在体外过表达时，Click-III/CaMKIγ被发现足以促进和促进去极化诱导的PC-12细胞的神经再生。

1.We examined the signaling pathway downstream of Rho that may be involved in regulating axonogenesis in cerebellar granule neurons in primary culture. These were chosen because these neurons have the interesting property of generating two bipolar axons immediately after plating, prior to further development of neurites, thereby greatly facilitating signaling analyses. We elucidated the essential positive role of the SDF-1α/Rho/mDial pathway in controlling the rate of axon elongation. As we previously discovered a negative regulatory role for the Rho/ROCK cascade, our data suggest that appropriate rate of axonogenesis might be tightly controlled by an antagonism between two distinct Rho effectors, ROCK and mDia1.2.We previously described how synaptic activity-induced calcium mobilization in hippocampal pyramidal neurons triggered actin recruitment to the spines. However, the critical molecules linking calcium with local actin reorganization remained unclear. We here examine whether a novel CaMK we identified as CLICK-III/CaMKIγ was potentially able to fill this role. When overexpressed in vitro, CLICK-III/CaMKIγ was found to be sufficient in promoting and facilitating depolarization-induced neuritogenesis in PC-12 cells.