Ｂ細胞の選択と生存におけるオートファジーの役割

自噬在 B 细胞选择和存活中的作用

基本信息

批准号：
15F15908
负责人：
黒崎知博
金额：
$ 1.47万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for JSPS Fellows
财政年份：
2015
资助国家：
日本
起止时间：
2015-04-24 至 2017-03-31
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15F15908/
关键词：
Autophagy Germinal center Rubicon B cell survival Secretory autophagy B cell

项目摘要

Understanding the survival control mechanism of long-lived, antibody-producing cells and memory B cells at the germinal center (GC) is required for developing a effective vaccine against various infectious diseases including influenza viruses. It is unclear whether enhanced autophagy alters GC B cell differentiation. Rubicon, an autophagy suppressor, was up-regulated in activated B cells, suggesting that Rubicon may suppress autophagy in B cells. To address these questions, we generated pan-B cell- and GC-B cell-specific Rubicon-mutant mouse, respectively. A decrease in antigen-specific high-affinity antibody production and an increase in autoantibody such as anti-DNA antibody were found in Rubicon-mutant mice, suggesting that Rubicon may play a role in the selection of antigen-specific B cell. However, a small-molecular-weight protein that seems to be a Rubicon isoform was found in Rubicon-mutant B cells, suggesting that deletion of the Rubicon gene is incomplete. Thus, it is necessary to confirm the present results and clarify the function of each isoform of Rubicon with the complete Rubicon-deficient mouse. On the other hand, we unexpectedly found that CD40 signal specifically induced the secretion of LC3-II containing exosomes, suggesting that CD40 signal is involved in secretory autophagy. In addition, such secretion was enhanced in the Rubicon-mutant cells. CD40 is an essential molecule during B cell-T cell interaction, and further study of CD40-induced secretory autophagy may reveal a novel mechanism of lymphocyte interaction via secretory autophagy or exosome.

要开发针对包括流感病毒在内的各种传染病的有效疫苗，需要了解生发中心 (GC) 的长寿抗体产生细胞和记忆 B 细胞的生存控制机制。目前尚不清楚增强的自噬是否会改变 GC B 细胞的分化。 Rubicon 是一种自噬抑制剂，在活化的 B 细胞中表达上调，表明 Rubicon 可能抑制 B 细胞中的自噬。为了解决这些问题，我们分别生成了泛 B 细胞和 GC-B 细胞特异性 Rubicon 突变小鼠。在 Rubicon 突变小鼠中发现抗原特异性高亲和力抗体产生减少和自身抗体（例如抗 DNA 抗体）增加，表明 Rubicon 可能在抗原特异性 B 细胞的选择中发挥作用。然而，在 Rubicon 突变 B 细胞中发现了一种似乎是 Rubicon 亚型的小分子量蛋白质，这表明 Rubicon 基因的删除并不完全。因此，有必要用完整的 Rubicon 缺陷小鼠来证实目前的结果并阐明 Rubicon 每种异构体的功能。另一方面，我们意外地发现CD40信号特异性诱导含有LC3-II的外泌体的分泌，表明CD40信号参与分泌性自噬。此外，这种分泌在 Rubicon 突变细胞中得到增强。 CD40是B细胞-T细胞相互作用过程中的重要分子，对CD40诱导的分泌性自噬的进一步研究可能会揭示通过分泌性自噬或外泌体进行淋巴细胞相互作用的新机制。