Phosphoinositide control of antigen cross-presentation by classical dendritic cells

经典树突状细胞对抗原交叉呈递的磷酸肌醇控制

• 批准号: RGPIN-2022-03041
• 负责人: Canton, Johnathan
• 金额: $ 2.7万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749608
• 关键词: Phosphoinositide; control; antigen; cross; presentation

To gather nutrients and information, cells sample their surroundings by internalizing material into organelles called endosomes. Endosomes are surrounded by a membrane which partitions the internalized material from the rest of the cell. Typically, internalized macromolecules, such as proteins or nucleic acids, cannot cross this membrane and are instead delivered to digestive organelles, called lysosomes, for conversion into small molecules and incorporation into the cell's metabolic pathways or for export as waste. In some exceptional instances, however, large undigested macromolecules are released from endosomes. This is especially evident in immune cells called dendritic cells (DCs). DCs transfer endocytosed macromolecules, including nucleic acids and proteins, into the cytosol where they can elicit inflammatory signalling or, in the case of proteins, are processed for presentation to T cells in a process known as antigen cross-presentation. This allows DCs to perform fundamental roles in homeostasis and immunity, yet how it happens is not known. This is the focus of my long-term research program, which will investigate how cells transfer macromolecules across endosomal membranes to elicit critical biological functions. This year, we made progress on this question by showing that large pores form on endocytic organelles in DCs. This allows for the escape of endocytosed proteins and is required for cross-presentation. But how do these putative endosomal pores form? We now have evidence that lipids called phosphoinositides drive endosomal pore formation and therefore cross-presentation. This, along with the fact that phosphoinositides mediate cellular events by recruiting protein effectors, leads to our hypothesis that phosphoinositides regulate macromolecular escape from endosomes by coordinating the formation of large pores through the recruitment of pore-forming protein effectors. Over the next 5 years, we will determine how phosphoinositides coordinate endosomal pore formation to facilitate the fundamental DC function of cross-presentation. Our aims are to: i)Identify the phosphoinositide species that regulate endosomal pore formation and cross-presentation ii)Identify the protein effectors that mediate endosomal pore formation and cross-presentation iii)Investigate the role of the putative pore-forming protein APOL7C in endosomal pore formation Beyond DCs, macromolecular escape from endosomes is implicated in key processes, such as inflammatory signalling, in many cell types. Our NSERC DG will therefore have widespread implications for fields ranging from cellular physiology to organismal homeostasis. We are in the ideal position to drive these discoveries and, in doing so, will (i) deliver unprecedented insight into the biology of cross-presentation, (ii) generate a toolbox for the investigation of phosphoinositides and their effectors and provide a (iii) training venue for HQP to build careers in academia and industry in Canada.

为了收集营养和信息，细胞通过将物质内化到称为内体的细胞器中来对其周围环境进行采样。内体被膜包围，膜将内化的物质与细胞的其余部分隔开。通常，内化的大分子，如蛋白质或核酸，不能穿过该膜，而是被递送到称为溶酶体的消化细胞器，用于转化为小分子并并入细胞的代谢途径或作为废物输出。然而，在某些例外情况下，大的未消化的大分子从内体释放。这在称为树突状细胞（DC）的免疫细胞中尤其明显。DC将内吞的大分子（包括核酸和蛋白质）转移到胞质溶胶中，在胞质溶胶中它们可以引发炎性信号传导，或者在蛋白质的情况下，被加工以在称为抗原交叉呈递的过程中呈递给T细胞。这使得DCs在体内平衡和免疫中发挥重要作用，但它是如何发生的尚不清楚。这是我长期研究计划的重点，该计划将研究细胞如何通过内体膜转移大分子以引发关键的生物功能。 今年，我们在这个问题上取得了进展，显示大孔形成的内吞细胞器在树突状细胞。这允许内吞蛋白的逃逸，并且是交叉呈递所需的。但是这些假定的内体孔是如何形成的呢？我们现在有证据表明，称为磷酸肌醇的脂质驱动内体孔的形成，因此交叉呈递。这沿着磷酸肌醇通过募集蛋白质效应物介导细胞事件的事实，导致我们的假设，即磷酸肌醇通过募集成孔蛋白效应物协调大孔的形成来调节大分子从内体逃逸。在接下来的5年里，我们将确定磷酸肌醇如何协调内体孔的形成，以促进交叉呈递的基本DC功能。我们的目标是：i）鉴定调节内体孔形成和交叉呈递的磷酸肌醇种类ii）鉴定介导内体孔形成和交叉呈递的蛋白效应物iii）研究推定的孔形成蛋白APOL7C在内体孔形成中的作用除了DC，大分子从内体逃逸涉及许多细胞类型中的关键过程，例如炎症信号传导。因此，我们的NSERC DG将对从细胞生理学到生物体内平衡的领域产生广泛的影响。我们处于推动这些发现的理想位置，并且在这样做的过程中，将（i）对交叉呈递的生物学提供前所未有的见解，（ii）为磷酸肌醇及其效应物的调查生成工具箱，并提供（iii）为HQP在加拿大学术界和工业界建立职业生涯的培训场所。