Cell Signaling and Immunity Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
Sci Signal. 2022 Jul 19;15(743):eabl9169. doi: 10.1126/scisignal.abl9169.
The integrin lymphocyte function-associated antigen 1 (LFA-1) helps to coordinate the migration, adhesion, and activation of T cells through interactions with intercellular adhesion molecule 1 (ICAM-1) and ICAM-2. LFA-1 is activated during the engagement of chemokine receptors and the T cell receptor (TCR) through inside-out signaling, a process that is partially mediated by phosphoinositide 3-kinase (PI3K) and its product phosphatidylinositol 3,4,5-trisphosphate (PIP). To evaluate potential roles of PI3K in LFA-1 activation, we designed a library of CRISPR/single guide RNAs targeting known and potential PIP-binding proteins and screened for effects on the ability of primary mouse T cells to bind to ICAM-1. We identified multiple proteins that regulated the binding of LFA-1 to ICAM-1, including the Rap1 and Ras GTPase-activating protein RASA3. We found that RASA3 suppressed LFA-1 activation in T cells, that its expression was rapidly reduced upon T cell activation, and that its activity was inhibited by PI3K. Loss of RASA3 in T cells led to increased Rap1 activation, defective lymph node entry and egress, and impaired responses to T-dependent immunization in mice. Our results reveal a critical role for RASA3 in T cell migration, homeostasis, and function.
整合素淋巴细胞功能相关抗原 1（LFA-1）通过与细胞间黏附分子 1（ICAM-1）和 ICAM-2 的相互作用，有助于协调 T 细胞的迁移、黏附和激活。LFA-1 在趋化因子受体和 T 细胞受体（TCR）的参与下通过内信号转导被激活，这一过程部分由磷酸肌醇 3-激酶（PI3K）及其产物磷脂酰肌醇 3,4,5-三磷酸（PIP）介导。为了评估 PI3K 在 LFA-1 激活中的潜在作用，我们设计了一个针对已知和潜在 PIP 结合蛋白的 CRISPR/single guide RNA 文库，并筛选其对原代小鼠 T 细胞与 ICAM-1 结合能力的影响。我们确定了多种调节 LFA-1 与 ICAM-1 结合的蛋白质，包括 Rap1 和 Ras GTPase 激活蛋白 RASA3。我们发现 RASA3 抑制 T 细胞中 LFA-1 的激活，T 细胞激活后其表达迅速降低，其活性被 PI3K 抑制。T 细胞中 RASA3 的缺失导致 Rap1 激活增加、淋巴结进出缺陷以及对 T 依赖性免疫接种的应答受损。我们的结果揭示了 RASA3 在 T 细胞迁移、稳态和功能中的关键作用。
