A transgenic model to study Bif-1 mediated neuroprotection in injury and disease

描述（由申请人提供）：越来越多的证据表明，线粒体功能障碍与在对影响大脑的损伤和疾病做出反应时观察到的神经变性相关且存在因果关系。虽然能量代谢和ATP产生的干扰受到了极大的关注，但在线粒体动力学的调节中也发现了异常，其中涉及影响线粒体形状和大小的融合和分裂（碎片化）过程。重要的是，线粒体融合和分裂直接参与确保它们的适当分布，运输和周转。考虑到神经元将健康的线粒体定位在能量需求部位是多么重要，不难想象，损害线粒体分裂和融合调节的遗传或表观遗传修饰可能会对神经元产生不利影响。 神经元连接、功能和活力。我们最近确定，神经元表达线粒体分裂调节蛋白Bif-1（Bif-1b/c）的两种选择性剪接形式。我们的初步数据表明，Bif-1b/c在大脑中动脉闭塞（MCAO，中风模型）小鼠的半影区（大脑皮层）的神经元中丢失。重要的是，Bif-1-null条件增强了由MCAO引起的神经元细胞死亡，以及培养物中的DNA损伤和Abeta细胞毒性。相反，Bif-1c过表达赋予针对Abeta介导的毒性的显著保护，表明Bif-1是正常神经元功能所需的。与年龄匹配的非AD患者相比，散发性阿尔茨海默病（AD）患者的顶叶皮质（受累区域）和突触体中的Bif-1b/c蛋白显著减少。在APPswe/PS1 dE 9小鼠AD模型和加入毒性Abeta肽后的原代皮层神经元中也观察到Bif-1b/c的这些变化。此外，在初步研究中，Bif-1缺失小鼠在一岁时表现出显着的认知障碍，果蝇中Bif-1同源物（endoB）的敲除增强了基于眼睛表型的有毒Abeta 42肽的毒性，但对表达无毒Abeta 40肽的苍蝇没有影响。这些发现表明Bif-1具有潜在的神经保护功能，并表明与缺血性损伤和AD相关的线粒体功能障碍可能是由于Bif-1b/c表达减少所致。我们建议测试的假设，即恢复诱导型转基因小鼠的神经元中的Bif-1c表达促进神经元的存活，线粒体的完整性的保留，并增强认知功能，在中风和AD的小鼠模型。这些研究将确定Bif-1c是否具有减少损伤和疾病引起的损伤的治疗作用。

DESCRIPTION (provided by applicant): Accumulating evidence demonstrates that mitochondrial dysfunction is both associated with and causally related to neurodegeneration observed in response to injury and diseases affecting the brain. While disturbances in energy metabolism and ATP production have received significant attention, abnormalities are also being found in the regulation of mitochondrial dynamics which involves the processes of fusion and fission (fragmentation) affecting the shape and size of mitochondria. Importantly, mitochondrial fusion and fission are directly involved in ensuring their proper distribution, transport, and turnover. Considering how vital it is for neurons to have healthy mitochondria positioned at sites of energy demand, it is not difficult to imagine that genetic or epigenetic modifications that impair the regulation of mitochondrial fission and fusion could adversely affect neuronal connectivity, function and viability. We recently determined that neurons express two alternatively spliced forms of a mitochondrial fission regulating protein, Bif-1 (Bif-1b/c). Our preliminary data demonstrates that Bif-1b/c is lost in neurons in the penumbra (cerebral cortex) of mice subjected to middle cerebral artery occlusion (MCAO, stroke model). Importantly, the Bif-1-null condition enhanced neuronal cell death caused by MCAO, and DNA damage and Abeta cytotoxicity in culture. Conversely, Bif-1c overexpression confers significant protection against Abeta-mediated toxicity indicating that Bif-1 is required for normal neuronal function. The Bif-1b/c protein is significantly reduced in the parietal cortex (affected area) and in synaptosomes of sporadic Alzheimer's disease (AD) patients compared to aged matched non-AD patients. These changes in Bif-1b/c are also observed in the APPswe/PS1dE9 mouse AD model and in primary cortical neurons following addition of the toxic Abeta peptide. Moreover, in preliminary studies, Bif-1-null mice displayed significant cognitive impairment at one year of age and knockout of the Bif-1 homologue (endoB) in drosophila enhanced the toxicity of the toxic Abeta42 peptide based on an eye phenotype, but had no effect on flies expressing the non-toxic Abeta40 peptide. These findings demonstrate a potential neuroprotective function of Bif-1 and suggest that mitochondrial dysfunction associated with ischemic damage and AD may be due to reduced expression of Bif-1b/c. We propose to test the hypothesis that restoration of Bif-1c expression in neurons in an inducible transgenic mouse promotes neuronal survival, retention of mitochondrial integrity and enhances cognitive function in response to stroke and in a mouse model of AD. These studies will determine if Bif-1c has therapeutic actions for reducing injury and disease-induced damage.