寨卡病毒感染致神经细胞线粒体融合/分裂异常的分子机制研究

Zika virus (ZIKV) is an enveloped, positive-strand RNA virus belonging to the Flavivirus genus of the Flaviviridae family. Growing evidences have demonstrated the connection between ZIKV infection and neurological disorders and congenital microcephaly. However，the underlying molecular mechanisms are poorly understood. Mitochondria are the primary energy-generating system of vital importance for cell growth and survival. Mitochondrial morphology dynamically changes in a balance of membrane fusion and fission to maintain functional mitochondria. Abnormal mitochondrial dynamics are implicated in the pathogenesis of neurological disorders, metabolic diseases, and viral infectious process and associated diseases. Clinical studies have revealed that the defect of mitochondrial fission was closely related to microcephaly. However, the molecular mechanisms involved in are still unknown. Recently, we found that ZIKV was able to infect several neuronal cell lines with high efficiency, and ZIKV infection induced mitochondrial elongation in neuronal cells due to imbalance expression of fusion/fission proteins. Based on these observations, we speculated that ZIKV may perturbs mitochondrial dynamics to attenuate neuronal cell growth. In this project, we will explore the molecular mechanisms underlying aberrant mitochondrial dynamics during ZIKV infection, using approaches involving infectious ZIKV neuronal cell cultures, proteomics, and molecular virology. Understanding of the molecular mechanisms involved in ZIKV infection may discover new therapeutic target for ZIKV-related neuronal diseases.

寨卡病毒（Zika virus，ZIKV）感染孕妇可导致新生儿小头畸形，但其致使神经系统损伤的分子机制并不清楚。线粒体是高度动态变化的细胞器，在细胞内不断融合和分裂以维持形态和数量的动态平衡。融合分裂的异常总是伴随着线粒体功能障碍，造成细胞功能的损害和疾病发生。临床研究发现小头症和线粒体动力学异常密切相关，但具体机制未见报道。我们前期建立了ZIKV感染的神经细胞模型，发现ZIKV可感染多种神经细胞系，并导致神经细胞中线粒体形态延长和融合/分裂蛋白表达发生变化。本项目将应用蛋白质组学等方法寻找参与ZIKV调节融合/分裂蛋白表达活化的信号转导通路，并通过构建病毒单个结构或非结构蛋白的表达质粒来验证起关键作用的病毒蛋白，明确ZIKV致线粒体融合/分裂失衡及细胞活性改变的分子机制。阐明线粒体动力学在抗ZIKV应答中的调控机制，有助于为解析ZIKV致病性、预防和控制ZIKV感染所致疾病提供科学依据。

线粒体自噬作为一种质量控制机制，有助于维持线粒体功能网络和细胞内稳态平衡。大量研究围绕自噬在寨卡病毒感染中的作用，但自噬诱导类型和机制尚不清楚。在前期研究中，我们发现寨卡病毒感染诱导了细胞内线粒体动力学异常，造成线粒体分裂加剧。在本课题中，我们在细胞及新生小鼠寨卡感染模型中首次发现ZIKV 诱导的线粒体融合分裂异常和线粒体自噬存在双向调控关系，并结合细胞生物学和病毒学等手段，筛选到病毒感染下介导线粒体自噬的宿主因子，并剖析在其中发挥重要作用的病毒蛋白，全面、深层次揭示病毒不同蛋白如何相互协作调控线粒体自噬过程，从而最大限度逃避宿主细胞的免疫反应并利用自噬体的双层膜结果便于自身复制，最终抑制神经细胞的增殖和诱发凋亡，导致神经损伤，为ZIKV致病机制研究提供新切入点。