Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, 66421, Homburg, Germany.
Bioanalytical Mass Spectrometry, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany.
Nat Commun. 2022 Feb 24;13(1):1029. doi: 10.1038/s41467-022-28596-y.
Cytotoxic T lymphocytes (CTL) kill malignant and infected cells through the directed release of cytotoxic proteins into the immunological synapse (IS). The cytotoxic protein granzyme B (GzmB) is released in its soluble form or in supramolecular attack particles (SMAP). We utilize synaptobrevin2-mRFP knock-in mice to isolate fusogenic cytotoxic granules in an unbiased manner and visualize them alone or in degranulating CTLs. We identified two classes of fusion-competent granules, single core granules (SCG) and multi core granules (MCG), with different diameter, morphology and protein composition. Functional analyses demonstrate that both classes of granules fuse with the plasma membrane at the IS. SCG fusion releases soluble GzmB. MCGs can be labelled with the SMAP marker thrombospondin-1 and their fusion releases intact SMAPs. We propose that CTLs use SCG fusion to fill the synaptic cleft with active cytotoxic proteins instantly and parallel MCG fusion to deliver latent SMAPs for delayed killing of refractory targets.
细胞毒性 T 淋巴细胞 (CTL) 通过将细胞毒性蛋白定向释放到免疫突触 (IS) 中来杀死恶性和感染细胞。细胞毒性蛋白颗粒酶 B (GzmB) 以可溶性形式或超分子攻击颗粒 (SMAP) 释放。我们利用突触融合蛋白 2-mRFP 敲入小鼠以非偏见的方式分离融合性细胞毒性颗粒，并单独或在脱颗粒 CTL 中观察它们。我们鉴定了两种融合能力的颗粒，单核核心颗粒 (SCG) 和多核核心颗粒 (MCG)，它们具有不同的直径、形态和蛋白组成。功能分析表明，这两种颗粒都在 IS 处与质膜融合。SCG 融合释放可溶性 GzmB。MCG 可以用 SMAP 标记物血小板反应蛋白-1 标记，其融合释放完整的 SMAP。我们提出 CTL 利用 SCG 融合立即将活性细胞毒性蛋白填充到突触间隙中，并平行于 MCG 融合以输送潜伏的 SMAP，用于延迟杀伤难治性靶标。
