Since stressing conditions induce a relocalization of endogenous human neuroglobin (NGB) to mitochondria, this research is aimed to evaluate the protective role of NGB overexpression against neurotoxic stimuli, through mitochondrial lipid raft-associated complexes. To this purpose, we built a neuronal model of oxidative stress by the use of human dopaminergic neuroblastoma cells, SK-N-BE2, stably overexpressing NGB by transfection and treated with 1-methyl-4-phenylpyridinium ion (MPP+). We preliminary observed the redistribution of NGB to mitochondria following MPP+ treatment. The analysis of mitochondrial raft-like microdomains revealed that, following MPP+ treatment, NGB translocated to raft fractions (Triton X-100-insoluble), where it interacts with ganglioside GD3. Interestingly, the administration of agents capable of perturbating microdomain before MPP+ treatment, significantly affected viability in SK-N-BE2-NGB cells. The overexpression of NGB was able to abrogate the mitochondrial injuries on complex IV activity or mitochondrial morphology induced by MPP+ administration. The protective action of NGB on mitochondria only takes place if the mitochondrial lipid(s) rafts-like microdomains are intact, indeed NGB fails to protect complex IV activity when purified mitochondria were treated with the lipid rafts disruptor methyl-β-cyclodextrin. Thus, our unique in vitro model of stably transfected cells overexpressing endogenous NGB allowed us to suggest that the role in neuroprotection played by NGB is reliable only through interaction with mitochondrial lipid raft-associated complexes.

由于应激条件会诱导内源性人类神经球蛋白（NGB）重新定位到线粒体，因此本研究旨在评估NGB通过线粒体脂质筏相关复合物对神经毒性刺激的保护作用。为此，我们通过使用人多巴胺能神经母细胞瘤细胞SK-N-BE2建立了氧化应激的神经元模型，该细胞通过转染稳定过表达NGB，并用1-甲基-4-苯基吡啶鎓离子（MPP +）处理。我们初步观察到MPP +处理后NGB向线粒体的重新分布。线粒体筏状微区的分析表明，经过MPP +处理后，NGB易位到筏级分（Triton X-100不溶），在其中与神经节苷脂GD3相互作用。有趣的是，在MPP +处理之前，能够干扰微区的药物的施用显着影响了SK-N-BE2-NGB细胞的生存能力。NGB的过表达能够消除因MPP +给药引起的复杂IV活性或线粒体形态引起的线粒体损伤。仅当线粒体脂质筏样微结构域完整时，NGB才对线粒体产生保护作用，实际上，当用脂质筏破坏剂甲基-β-环糊精处理纯化的线粒体时，NGB不能保护复杂的IV活性。因此，我们独特的 仅当线粒体脂质筏样微结构域完整时，NGB才对线粒体产生保护作用，实际上，当用脂质筏破坏剂甲基-β-环糊精处理纯化的线粒体时，NGB不能保护复杂的IV活性。因此，我们独特的 仅当线粒体脂质筏样微结构域完整时，NGB才对线粒体产生保护作用，实际上，当用脂质筏破坏剂甲基-β-环糊精处理纯化的线粒体时，NGB不能保护复杂的IV活性。因此，我们独特的过表达内源性NGB的稳定转染细胞的体外模型使我们提出，只有通过与线粒体脂质筏相关复合物的相互作用，NGB在神经保护作用中的作用才是可靠的。