MITOCHONDRIAL FISSION AND NEUROGENERATION

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 EM断层扫描显示，暴露于锌(锌)和一氧化氮(NO)后，线粒体发生了显着的重塑。一氧化氮和锌离子参与了脑缺血和其他神经退行性疾病的发病机制。然而，当我们开始这项合作时，它们的神经毒性作用的关系和分子基础还不清楚。最近，我们发现一氧化氮/过氧亚硝酸盐(NO/ONOO-)导致原代皮质神经元细胞内锌离子的释放。同样，病理生理刺激，如N-甲基-D-天冬氨酸受体过度激活，导致细胞内游离锌离子水平增加。游离锌离子反过来影响线粒体功能，导致呼吸阻断、细胞色素c释放、活性氧的产生和p38蛋白激酶的激活。此外，电子显微镜断层扫描发现，与钙离子类似，锌离子也能引起线粒体肿胀。此外，时间推移显微镜显示，这一途径导致快速的caspase非依赖性K+外流伴随细胞萎缩；膜片钳记录显示电压门控K+通道的激活是这种K+外流的基础。重要的是，锌离子螯合剂、ROS清除剂、Bclxl过表达、显性负性p38或K+通道抑制剂都延迟了NO诱导的K+外流、细胞体积损失和神经元凋亡。因此，这些结果表明，NO和锌离子凋亡信号通路之间存在一种以前未知的串扰，可能参与了神经退行性变的发病机制。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. EM tomography revealed a striking remodeling of mitochondria following exposure to zinc (Zn2+) and nitric oxide (NO). Nitric oxide and Zn2+ are implicated in the pathogenesis of cerebral ischemia and other neurodegenerative diseases. However, the relationship and the molecular basis of their neurotoxic effects were unclear when we started this collaboration. Recently, we showed that nitric oxide/peroxynitrite (NO/ONOO-) leads to liberation of Zn2+ from intracellular stores in primary cortical neurons. Similarly, pathophysiological stimuli, like N-methyl-D-aspartate receptor overactivation, resulted in increased free intracellular Zn2+ levels. Free Zn2+, in turn, impinges on mitochondrial function inducing respiratory block, cytochrome c release, generation of reactive oxygen species, and p38 MAP kinase activation. In addition, Zn2+, similar to Ca2+, induced mitochondrial swelling detected by electron microscope tomography. Additionally, time-lapse microscopy revealed that this pathway lead to rapid caspase-independent K+ efflux with concomitant cell shrinkage; patch-clamp recording showed that activation of voltage-gated K+ channels underlies this K+ efflux. Importantly, Zn2+ chelators, ROS scavengers, Bcl-xL overexpression, dominant-negative p38, or K+ channel inhibitors all delayed NO-induced K+ efflux, cell volume loss, and neuronal apoptosis. Thus, these results suggest a previously unknown crosstalk between NO and Zn2+ apoptotic signaling pathways that may contribute the pathogenesis of neurodegeneration.