Characterization of extracellular microvesicles generated by immature B cell as mediators of cell-cell communication

未成熟 B 细胞产生的细胞外微泡作为细胞间通讯介质的表征

• 批准号: RGPIN-2017-04630
• 负责人: Christian, Sherri
• 金额: $ 1.89万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=647664
• 关键词: Characterization; extracellular; microvesicles; generated; immature

Cells can respond to the their environment through interaction with proteins released from other cells as well as direct interactions with other cells. However, recently, it has been appreciated that cells can also communicate with each other through vesicles that are either secreted, called exosomes, or bud off from the plasma membrane, called microvesicles (MV). Collectively exosomes and MV are termed extracellular vesicles (EV). EV are coated with selected cellular proteins and filled with intracellular membrane and cytosolic proteins, as well as regulatory RNA and mRNA. The transfer of proteins and RNA from donor cells via EV can cause the recipient cells to take on new functions and characteristics. B lymphocytes (B cells) are the antibody-producing cells of the immune system. It is important that B cell development is properly regulated to acquire a properly functioning immune system. Recently, we found that immature B cells release MV when a cell surface receptor called CD24 is stimulated to mimic ligand-mediated clustering. These MV carry CD24 on their surface and caused a redistribution of CD24 among the B cell population. It is known that clustering of CD24 causes apoptosis of immature B cells however the function of the CD24-bearing MV is not known. In addition, the mechanisms that regulate MV release in general are poorly understood. Finally, it is not clear how CD24 can promote the generation of MV since it is anchored to the outside of the cell and it does not have a transmembrane domain through which to transmit signals into the cell. Thus, the goal of this proposal is to understand how these MV are generated and the role that they play in regulating cell-cell communication between B cells and target cells. Immature B cells develop in the bone marrow in close proximity to cells that support B cell development, which are called stromal cells. Therefore, we will first determine if MV can be taken up by stromal cells to affect their function. Next, we will identify the key pathways that regulate the generation of MV and determine if MV generation is a common response upon engagement of other receptors. Lastly, we will identify the key partners that allow CD24 to transmit signals into the cell. Overall, these studies will advance our understanding of how MV can regulate recipient cell function and significantly increase our understanding of how MV are generated. Moreover, this work may provide novel insights into how MV can contribute to B cell development. Understanding the role and regulation of MV will impact all areas of cell biology as EV are highly conserved mediators of cell-cell communication.

细胞可以通过与其他细胞释放的蛋白质相互作用以及与其他细胞的直接相互作用来对环境做出反应。然而，最近，人们认识到细胞也可以通过囊泡相互交流，这些囊泡要么是分泌的，称为外泌体，要么是从质膜上萌发的，称为微囊泡（MV）。外泌体和MV统称为细胞外囊泡（EV）。EV包被选定的细胞蛋白，并充满胞内膜和胞质蛋白，以及调控RNA和mRNA。供体细胞的蛋白质和RNA通过EV转移可使受体细胞具有新的功能和特征。B淋巴细胞（B细胞）是免疫系统的抗体产生细胞。重要的是，B细胞的发育得到适当的调节，以获得一个正常运作的免疫系统。最近，我们发现未成熟的B细胞在被称为CD24的细胞表面受体刺激以模拟配体介导的聚类时释放MV。这些MV在其表面携带CD24，并在B细胞群中引起CD24的重新分配。已知CD24的聚集可引起未成熟B细胞的凋亡，但携带CD24的MV的功能尚不清楚。此外，一般来说，调控MV释放的机制尚不清楚。最后，目前尚不清楚CD24是如何促进MV的产生的，因为它锚定在细胞外部，并且它没有跨膜结构域，通过跨膜结构域将信号传递到细胞中。因此，本提案的目标是了解这些MV是如何产生的，以及它们在调节B细胞和靶细胞之间的细胞间通讯中所起的作用。未成熟的B细胞在骨髓中靠近支持B细胞发育的细胞（称为基质细胞）发育。因此，我们将首先确定基质细胞是否会摄取MV从而影响其功能。接下来，我们将确定调节MV生成的关键途径，并确定MV生成是否是其他受体参与时的共同反应。最后，我们将确定允许CD24将信号传递到细胞中的关键伙伴。总的来说，这些研究将促进我们对MV如何调节受体细胞功能的理解，并显著增加我们对MV如何产生的理解。此外，这项工作可能为MV如何促进B细胞发育提供新的见解。了解MV的作用和调控将影响细胞生物学的所有领域，因为MV是细胞-细胞通讯的高度保守介质。