Neuroprotection Research Laboratory, Departments of Neurology and Radiology, Massachusetts General Hospital, Charlestown, MA, USA.
Neuroscience. 2012 Aug 30;218:235-42. doi: 10.1016/j.neuroscience.2012.05.054. Epub 2012 May 29.
Neuroglobin (Ngb) is a new member of the globin family and a novel endogenous neuroprotective molecule, but its neuroprotective mechanisms remain largely undefined. Previous studies suggest Ngb is both physically and functionally related to mitochondria, however without direct evidence. Our recent discovery has shown that Ngb can physically interact with a number of mitochondrial proteins. In this study we aimed to define the physical interaction between Ngb and mitochondria by determining whether there is a mitochondrial distribution of Ngb under both physiological-resting and pathological oxygen-glucose deprivation (OGD) conditions. Western blot for the first time revealed a small portion of Ngb was physically localized in mitochondria, and the relative mitochondrial Ngb level was significantly increased after OGD in primary-cultured mouse cortical neurons, indicating a translocation of Ngb into mitochondria. Complementary approaches including confocal imaging and immuno-electron microscopy confirmed Ngb distribution in mitochondria under both basal-resting condition and OGD. Inhibitors of mitochondria permeability transition pore (mPTP) and Voltage-Dependent Anion Channel (VDAC) blocked OGD-induced increase of mitochondrial Ngb level, demonstrating a possible role of mPTP in Ngb's mitochondrial translocation. We further found that Ngb overexpression-conferred neuroprotection was correlated with increased mitochondrial Ngb level, suggesting the mitochondria distribution of Ngb is clearly associated with and may contribute to Ngb's neuroprotection.
神经球蛋白（Ngb）是球蛋白家族的新成员，也是一种新型的内源性神经保护分子，但它的神经保护机制在很大程度上仍未得到阐明。先前的研究表明，Ngb 在物理上和功能上都与线粒体有关，但没有直接的证据。我们最近的发现表明，Ngb 可以与许多线粒体蛋白发生物理相互作用。在这项研究中，我们旨在通过确定 Ngb 在生理休息和病理缺氧葡萄糖剥夺（OGD）条件下是否在线粒体中分布来定义 Ngb 与线粒体之间的物理相互作用。首次通过 Western blot 发现一小部分 Ngb 在线粒体中存在物理定位，并且在原代培养的小鼠皮质神经元中 OGD 后相对线粒体 Ngb 水平显着增加，表明 Ngb 向线粒体易位。包括共聚焦成像和免疫电子显微镜在内的补充方法证实了 Ngb 在基础休息和 OGD 条件下在线粒体中的分布。线粒体通透性转换孔（mPTP）和电压依赖性阴离子通道（VDAC）抑制剂阻断了 OGD 诱导的线粒体 Ngb 水平升高，表明 mPTP 在 Ngb 的线粒体易位中可能起作用。我们进一步发现，Ngb 过表达赋予的神经保护作用与线粒体 Ngb 水平的增加相关，表明 Ngb 的线粒体分布与 Ngb 的神经保护作用明显相关并可能有助于其发挥作用。
