Lampe Kristin, Endale Mehari, Cashman Siobhan, Fang Hao, Mattner Jochen, Hildeman David, Hoebe Kasper
Division of Immunobiology, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH, USA.
Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Sciences, Kennedy Institute of Rheumatology, University of Oxford, Oxford, UK.
Eur J Immunol. 2015 Jul;45(7):2072-83. doi: 10.1002/eji.201445352. Epub 2015 May 22.
Absence of MHC class I expression is an important mechanism by which NK cells recognize a variety of target cells, yet the pathways underlying "missing-self" recognition, including the involvement of activating receptors, remain poorly understood. Using ethyl-N-nitrosourea mutagenesis in mice, we identified a germline mutant, designated Ace, with a marked defect in NK cell mediated recognition and elimination of "missing-self" targets. The causative mutation was linked to chromosome 11 and identified as a missense mutation (Thr428Ile) in the SH2 domain of Slp-76-a critical adapter molecule downstream of ITAM-containing surface receptors. The Slp-76 Ace mutation behaved as a hypomorphic allele-while no major defects were observed in conventional T-cell development/function, a marked defect in NK cell mediated elimination of β2-microglobulin (β2M) deficient target cells was observed. Further studies revealed Slp-76 to control NK-cell receptor expression and maturation; however, activation of Slp-76(ace/ace) NK cells through ITAM-containing NK-cell receptors or allogeneic/tumor target cells appeared largely unaffected. Imagestream analysis of the NK-β2M(-/-) target cell synapse revealed a specific defect in actin recruitment to the conjugate synapse in Slp-76(ace/ace) NK cells. Overall these studies establish Slp-76 as a critical determinant of NK-cell development and NK cell mediated elimination of missing-self target cells in mice.
主要组织相容性复合体（MHC）I类分子表达缺失是自然杀伤（NK）细胞识别多种靶细胞的重要机制，然而，包括激活受体参与在内的“缺失自我”识别的潜在途径仍知之甚少。利用N-亚硝基乙基脲对小鼠进行诱变，我们鉴定出一种种系突变体，命名为Ace，其在NK细胞介导的对“缺失自我”靶标的识别和清除方面存在明显缺陷。致病突变与11号染色体相关，并被鉴定为Slp-76（含免疫受体酪氨酸活化基序（ITAM）的表面受体下游的关键衔接分子）的SH2结构域中的错义突变（苏氨酸428异亮氨酸）。Slp-76 Ace突变表现为一种亚效等位基因——虽然在传统T细胞发育/功能中未观察到主要缺陷，但在NK细胞介导的清除β2-微球蛋白（β2M）缺陷靶细胞方面观察到明显缺陷。进一步研究表明，Slp-76可控制NK细胞受体的表达和成熟；然而，通过含ITAM的NK细胞受体或同种异体/肿瘤靶细胞激活Slp-76（ace/ace）NK细胞在很大程度上未受影响。对NK-β2M（-/-）靶细胞突触的图像流式细胞分析显示，Slp-76（ace/ace）NK细胞中肌动蛋白募集到结合突触存在特异性缺陷。总体而言，这些研究确定Slp-76是小鼠NK细胞发育和NK细胞介导的清除缺失自我靶细胞的关键决定因素。
