脑红蛋白与线粒体蛋白VDAC和CYC1相互作用抑制缺氧/缺血损伤所致神经细胞死亡

Cerebrovascular disorder, mainly consisting of ischemic stroke, remains as the most deadly disease in China. Although there are a variety of existing clinical treatment against ischemic stroke, the result is not satisfactory. Neuroglobin is a newly discovered globin that binds to oxygen with high affinity. Accumulating evidence have proved neuroglobin to be an endogenous neuroprotective molecule against hypoxic/ischemic brain injury both in vivo and in vitro. However, the molecular mechanisms of neuroglobin's neuroprotection remain poorly understood. It is well known that mitochondria dysfunction plays a key role in hypoxic/ischemic neuron death. Interestingly, neuroglobin has been reported to be closely related to mitochondria both functionally and physically. We for the first time performed a yeast two-hybrid assay to search for interaction partners of neuroglobin. Two mitochondrial proteins were identified in this assay and confirmed in primary cortical neurons by Co-IP, including Voltage Dependent Anion Channel (VDAC) and Cytochrome c1 (CYC1). With our preliminary data, we hypothesize that neuroglobin improves mitochondria function that protects against ischemia/hypoxia-induced neuronal death via interaction with mitochondria proteins VDAC for inhibiting mPTP opening and complex III (Cyc1) for diminishing ROS production. We believe research into better understanding the molecular mechanisms of neuroglobin's neurorotection would lead to development of new therapeutic approaches against stroke and related disorders.

脑血管病是我国第一大致死疾病，多为缺血性脑卒中，临床虽有多种治疗手段，结果却并不令人满意。脑红蛋白是新近发现的一种结合组织氧的球蛋白，诸多研究表明脑红蛋白为一种内源性神经保护因子，可对抗缺血性脑卒中的发生发展，但其作用机制尚不明确。已知线粒体功能失调在缺氧/缺血所致神经细胞死亡中扮演了重要角色，而脑红蛋白与线粒体在结构与功能上密切相关。本课题组前期通过酵母双杂交发现二个与脑红蛋白结合的蛋白质，即电压依赖性阴离子通道（VDAC）和细胞色素C1（CYC1），随后，通过免疫共沉淀在神经细胞中得以证实，但其具体作用机制仍有待阐明。由此，我们提出假设：脑红蛋白通过与线粒体蛋白VDAC相互作用抑制线粒体通透性转换孔（MPTP）的开放、与线粒体呼吸链复合物III的CYC1亚基相互作用抑制反应性氧自由基的生成，通过改善线粒体功能抑制缺氧/缺血所致神经细胞死亡，本假设的验证将为缺血性脑卒中防治提供新的靶点。

脑血管病是我国第一大致死疾病，多为缺血性脑卒中，临床虽有多种治疗手段，结果却并不令人满意。脑红蛋白（Ngb）是近几年发现的在神经元里特异表达的一种球蛋白。Ngb超表达对脑缺氧/缺血损伤具有明显的保护作用，但其作用机理尚未阐明。初步研究表明在缺氧状态下，Ngb 能影响线粒体的功能。本课题组首次证明了Ngb能从细胞浆转移至线粒体。为了寻找线粒体内与Ngb相互作用的蛋白，我们进行了酵母双杂交实验，筛选出了一批目标蛋白，其中一个是细胞色素c1，是细胞色素bc1复合物的一个亚基。研究数据显示在缺氧-复氧状态下细胞色素bc1产生活性氧的活性升高，而Ngb超表达能抑制这种升高。随后，本课题进一步研究Ngb与细胞色素bc1的相互作用及与神经保护的关系，Ngb在缺氧-复氧状态下在胞浆和线粒体中的动态转移,首次发现脑红蛋白存在于线粒体中，并且其在线粒体中的含量随着缺氧缺糖条件下升高；脑红蛋白高表达能够降低OGD引起的Complex III活性的增加，并抑制ROS的产生。本研究将为针对脑缺氧/缺血损伤的药物及相关机制研究提供新的思路。