MITOCHONDRIAL FISSION AND NEUROGENERATION

这个子项目是许多利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 EM断层扫描显示，暴露于锌（Zn 2+）和一氧化氮（NO）后，线粒体显著重塑。一氧化氮和锌离子参与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-）导致释放的锌2+从细胞内存储在原代皮层神经元。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Zn 2+水平增加。游离Zn 2+反过来影响线粒体功能，诱导呼吸阻滞、细胞色素c释放、活性氧物质的产生和p38 MAP激酶活化。此外，Zn 2+，类似于Ca 2+，诱导线粒体肿胀检测到的电子显微镜断层扫描。此外，延时显微镜显示，这一途径导致快速的半胱天冬酶非依赖性K+流出伴随细胞收缩;膜片钳记录表明，电压门控K+通道的激活是K+流出的基础。重要的是，Zn 2+螯合剂，ROS清除剂，Bcl-xL过表达，显性负性p38或K+通道抑制剂都延迟NO诱导的K+流出，细胞体积损失和神经元凋亡。因此，这些结果表明，以前未知的串扰之间的NO和Zn 2+凋亡信号通路，可能有助于神经变性的发病机制。

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.