拟南芥内质网蛋白AMP1调控蛋白稳态平衡和衰老的分子机制

The initiation and progression of senescence in higher plants is vital for seed development, life cycle and crop production. The loss of protein homeostasis (proteostasis) is one of the hallmarks of aging in plants. Maintenance of proteostasis is also key to the stress responses and the regulation of senescence in plants. However, the regulation of proteostasis and senescence in higher plants is still not fully understood. In our preliminary work, we developed an assay in Arabidopsis seedlings to examine dark/carbon starvation-induced senescence. Utilizing this assay, we established that Arabidopsis ER protein AMP1 functions as a negative regulator of dark/carbon starvation-induced protein degradation and senescence. In this project, we propose to carry out works on three fronts to understand how AMP1 regulates proteostasis and senescence under carbon starvation. We will combine genetic interaction analysis, monitoring protein degradation pathways and RNA-seq analysis to demonstrate the relationship between AMP1 and ER-related proteostasis pathways. We will track the dynamic changes of ER and AMP1 subcellular localization upon carbon starvation to understand the cellular basis of AMP1’s role. We will screen for AMP1 interacting partners under carbon starvation. Our work will uncover the molecular mechanisms of how AMP1 regulates proteostasis and senescence in response to carbon starvation stress, establish the AMP1-mediated senescence regulating pathway and provide new gene resources for artificial manipulation of senescence in crops.

高等植物衰老的启动和进程对种子发育、世代交替和作物产量至关重要。蛋白稳态平衡的丧失是植物衰老的关键特征之一。蛋白稳态平衡的维持也是植物逆境响应和衰老调控的重要环节，但植物中蛋白稳态平衡和衰老的调控机理还不十分清楚。在前期工作中，本项目组建立了一个黑暗碳饥饿诱导衰老的实验体系，利用这一体系发现拟南芥内质网蛋白AMP1负调控碳饥饿胁迫诱导的蛋白降解和植物衰老过程。本项目拟通过遗传互作分析、蛋白降解过程追踪和转录组分析，揭示AMP1与内质网相关的蛋白稳态平衡调控途径的关系；通过内质网和AMP1蛋白动态变化的观察，阐明AMP1调控碳饥饿胁迫下蛋白稳态和衰老的细胞学机理；通过互作蛋白筛选，鉴定碳饥饿胁迫下AMP1参与的蛋白复合体。这三方面的工作将揭示AMP1响应碳饥饿胁迫，调控蛋白稳态平衡和衰老的分子机制，建立一个新的AMP1介导的植物衰老调控途径，为人工调控植物衰老提供新的基因资源。

衰老是有机体生长发育的最终环节，在个体、器官、细胞和分子水平受到精细调控。植物衰老对于种子发育和作物产量建成至关重要。弱光或黑暗抑制光合作用，使得植物处于碳饥饿状态，激活降解代谢和衰老。黑暗胁迫诱导的植物衰老过程受到自噬通路和晚期内体定位的ABS3亚家族MATE转运蛋白介导的衰老通路的调控。前期工作中，建立了一个黑暗碳饥饿胁迫诱导拟南芥幼苗衰老的实验体系，并发现定位于内质网的拟南芥ALTERED MERISTEM PROGRAM1（AMP1）蛋白功能缺失导致碳饥饿胁迫下衰老加剧的表型。基于转录组数据，研究了AMP1基因响应黑暗碳饥饿胁迫的表达模式。发现AMP1的亚细胞定位特征受到黑暗碳饥饿胁迫的调控。遗传互作分析表明AMP1参与的衰老通路与自噬通路不同，但很可能参与ABS3介导的衰老通路。同时还开展了HOOKLESS1（HLS1）参与衰老调控的分子机制研究，发现HLS1能够定位于晚期内体并与ATG8互作，同时抑制ATG8-ABS3互作以及ABS3的液泡转运，进而负调控植物衰老，并且HLS1抑制衰老的功能在拟南芥和小麦中保守。本项目的研究揭示了AMP1和HLS1蛋白负调控植物衰老的分子机制，从遗传、细胞和生化等不同角度进一步揭示了本课题组前期发现的ABS3亚家族MATE转运蛋白介导的植物衰老通路的组分和调控机制，丰富了对黑暗碳饥饿胁迫诱导衰老的基因调控网络的认识，为人工改造优化作物衰老性状提供了基因资源和理论基础。