Division of Rheumatology, Immunology and Allergy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115 Division of Cell Biology and Immunology, Institute of Microbial Technology, Chandigarh 160036, India Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115 Institut National de la Santé et de la Recherche Médicale, Unité 753, Institut Gustave Roussy, Villejuif 75654, France Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104 Department of Biological Sciences, Indian Institute of Science Education and Research, Mohali 140306, India Immunology, Allergy and Rheumatology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030.
Mol Biol Cell. 2013 Dec;24(23):3721-35. doi: 10.1091/mbc.E13-05-0259. Epub 2013 Oct 2.
Natural killer (NK) lymphocytes contain lysosome-related organelles (LROs), known as lytic granules, which upon formation of immune synapse with the target cell, polarize toward the immune synapse to deliver their contents to the target cell membrane. Here, we identify a small GTP-binding protein, ADP-ribosylation factor-like 8b (Arl8b), as a critical factor required for NK cell-mediated cytotoxicity. Our findings indicate that Arl8b drives the polarization of lytic granules and microtubule-organizing centers (MTOCs) toward the immune synapse between effector NK lymphocytes and target cells. Using a glutathione S-transferase pull-down approach, we identify kinesin family member 5B (KIF5B; the heavy chain of kinesin-1) as an interaction partner of Arl8b from NK cell lysates. Previous studies showed that interaction between kinesin-1 and Arl8b is mediated by SifA and kinesin-interacting protein (SKIP) and the tripartite complex drives the anterograde movement of lysosomes. Silencing of both KIF5B and SKIP in NK cells, similar to Arl8b, led to failure of MTOC-lytic granule polarization to the immune synapse, suggesting that Arl8b and kinesin-1 together control this critical step in NK cell cytotoxicity.
自然杀伤 (NK) 淋巴细胞含有溶酶体相关细胞器 (LRO)，称为溶酶体颗粒，当与靶细胞形成免疫突触时，这些溶酶体颗粒会向免疫突触极化，将其内容物递送到靶细胞膜。在这里，我们鉴定出一种小 GTP 结合蛋白，ADP-ribosylation factor-like 8b (Arl8b)，作为 NK 细胞介导的细胞毒性所必需的关键因素。我们的研究结果表明，Arl8b 驱动溶酶体颗粒和微管组织中心 (MTOC) 向效应 NK 淋巴细胞和靶细胞之间的免疫突触极化。使用谷胱甘肽 S-转移酶下拉方法，我们从 NK 细胞裂解物中鉴定出驱动蛋白家族成员 5B (KIF5B; 驱动蛋白-1 的重链) 是 Arl8b 的相互作用伙伴。先前的研究表明，驱动蛋白-1 和 Arl8b 之间的相互作用由 SifA 和驱动蛋白相互作用蛋白 (SKIP) 介导，三组分复合物驱动溶酶体的正向运动。沉默 NK 细胞中的 KIF5B 和 SKIP，与 Arl8b 相似，导致 MTOC-溶酶体颗粒向免疫突触的极化失败，表明 Arl8b 和驱动蛋白-1 一起控制 NK 细胞细胞毒性的这一关键步骤。
