The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.
Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia.
Nat Commun. 2020 Jun 19;11(1):3151. doi: 10.1038/s41467-020-16887-1.
Mixed lineage kinase domain-like (MLKL) is the terminal protein in the pro-inflammatory necroptotic cell death program. RIPK3-mediated phosphorylation is thought to initiate MLKL oligomerization, membrane translocation and membrane disruption, although the precise choreography of events is incompletely understood. Here, we use single-cell imaging approaches to map the chronology of endogenous human MLKL activation during necroptosis. During the effector phase of necroptosis, we observe that phosphorylated MLKL assembles into higher order species on presumed cytoplasmic necrosomes. Subsequently, MLKL co-traffics with tight junction proteins to the cell periphery via Golgi-microtubule-actin-dependent mechanisms. MLKL and tight junction proteins then steadily co-accumulate at the plasma membrane as heterogeneous micron-sized hotspots. Our studies identify MLKL trafficking and plasma membrane accumulation as crucial necroptosis checkpoints. Furthermore, the accumulation of phosphorylated MLKL at intercellular junctions accelerates necroptosis between neighbouring cells, which may be relevant to inflammatory bowel disease and other necroptosis-mediated enteropathies.
混合谱系激酶结构域样（MLKL）是促炎坏死性细胞死亡程序中的末端蛋白。RIPK3 介导的磷酸化被认为是 MLKL 寡聚化、膜易位和膜破坏的起始事件，尽管事件的确切顺序尚不完全清楚。在这里，我们使用单细胞成像方法来绘制内源性人 MLKL 在坏死性细胞死亡过程中的激活顺序。在坏死性细胞死亡的效应阶段，我们观察到磷酸化的 MLKL 在假定的细胞质坏死小体上组装成更高阶的物种。随后，MLKL 通过高尔基体-微管-肌动蛋白依赖的机制与紧密连接蛋白一起运输到细胞外周。MLKL 和紧密连接蛋白随后作为异质的微米大小热点稳定地在质膜上积累。我们的研究确定了 MLKL 的运输和质膜积累是坏死性细胞死亡的关键检查点。此外，磷酸化 MLKL 在细胞间连接点的积累加速了相邻细胞之间的坏死性细胞死亡，这可能与炎症性肠病和其他坏死性细胞死亡介导的肠病有关。
