HS1 Function in Dendritic Cells

描述(申请人提供)：树突状细胞(DC)在免疫反应中发挥关键作用，它收集周围组织中的病原体和肿瘤细胞碎片，并将其作为多肽递送到淋巴结，提交给T细胞。DC的功能在很大程度上依赖于肌动蛋白的细胞骨架，而像黄蜂这样的肌动蛋白调节蛋白的突变会导致与免疫缺陷和自身免疫相关的DC功能缺陷。在T细胞中，我们之前展示了黄蜂与另一种肌动蛋白调节蛋白HS1协同工作。HS1也在树突状细胞中表达，我们的初步数据表明，HS1是有效的抗原提呈所必需的。此外，我们发现HS1是组织足小体所必需的，是细胞在组织中迁移过程中与细胞外基质黏附所需的结构，以及基质金属蛋白酶的沉积。我们假设HS1在DC中与黄蜂和动力素II共同作用，控制受体介导的内吞作用和足体依赖向淋巴器官的迁移。为了验证这一假设，我们将实现三个目标。首先，我们将测试HS1与Dynamin II的相互作用在受体介导的内吞作用中驱动囊泡内化的作用，并询问HS1是否也需要参与内化抗原的细胞内运输和处理的额外步骤。其次，我们将利用视频显微镜研究迁移的BMDCs的板脂和足体动力学，询问HS1是否是分泌基质金属蛋白酶所必需的，并在体内测试HS1-/-DC迁移到淋巴结的能力。第三，我们将进行结构-功能研究，以检验这一假设，即HS1的C末端SH3结构域通过与黄蜂和Dynamin II的调控相互作用，在内吞和迁移过程中指导其肌动蛋白调节功能。综上所述，这些研究将是对树突状细胞中HS1功能的首次仔细分析，并将为肌动蛋白调控途径如何控制DC功能的特定方面提供重要的新见解。这些信息将对制定由于肌动蛋白调节蛋白突变而引起的免疫缺陷和自身免疫性疾病的治疗策略，以及开发有效的基于DC的疫苗和免疫疗法具有价值。 与公共卫生相关：树突状细胞功能的几个方面依赖于细胞结构的高度协调变化，关键细胞骨架调节蛋白的突变会导致严重的免疫缺陷或狼疮。这项建议阐述了一种重要的细胞骨架调节蛋白HS1在树突状细胞功能的特定方面的作用。从这些研究中获得的知识对于了解免疫缺陷和自身免疫性疾病的基础，以及开发有效的树突状细胞疫苗将是重要的。

DESCRIPTION (provided by applicant): Dendritic cells (DCs) play a pivotal role in the immune response, by collecting pathogens and tumor cell debris in peripheral tissues, and delivering these as peptides to lymph nodes for presentation to T cells. DC function relies heavily on the actin cytoskeleton, and mutations in actin-regulatory proteins like WASp lead to defects in DC function associated with immunodeficiency and autoimmunity. In T cells, we showed previously that WASp works together with another actin regulatory protein, HS1. HS1 is also expressed in dendritic cells, and our preliminary data show that HS1 is required for efficient antigen presentation. In addition, we find that HS1 is required for organization of podosomes, structures required for adhesion to the extracellular matrix and matrix metalloproteinase deposition during cell migration through tissues. We hypothesize that HS1 works together with WASp and dynamin II in DCs, to control receptor-mediated endocytosis and podosome- dependent migration to lymphoid organs. To test this hypothesis, we will carry out three Aims. First, we will test the role of HS1 interactions with dynamin II in driving vesicle internalization during receptor-mediated endocytosis, and ask if HS1 is also required for additional steps the intracellular transport and processing of internalized antigens. Second, we will investigate lamellipodial and podosome dynamics in migrating BMDCs using video microscopy, ask if HS1 is required for secretion of matrix metalloproteinases, and test the ability of HS1-/- DCs to migrate to lymph nodes in vivo. Third, we will conduct structure-function studies to test the hypothesis that the C-terminal SH3 domain of HS1 directs its actin-regulatory functions during endocytosis and migration via regulated interactions with WASp and dynamin II. Taken together, these studies will represent the first careful analysis of HS1 function in dendritic cells, and will provide important new insights into how actin regulatory pathways control specific aspects of DC function. This information will be valuable for developing therapeutic strategies for immunodeficiency and autoimmune diseases that arise as a result of mutations in actin-regulatory proteins, and for the development of effective DC-based vaccines and immunotherapies. PUBLIC HEALTH RELEVANCE: Several aspects of dendritic cell function depend on highly orchestrated changes in cell structure, and mutations in key cytoskeletal regulatory proteins lead to severe immunodeficiency or Lupus. This proposal addresses the role of one important cytoskeletal regulatory protein, HS1, in specific aspects of dendritic cell function. The knowledge gained from these studies will be important for understanding the basis of immunodeficiency and autoimmune disease, and for the development of effective dendritic cell-based vaccines.