Unveiling the Role of RAB27A in Necroptosis: A CRISPR Knockout Screen Reveals a Key Player in Membrane Recruitment and Transport of the NECROSOME

Necroptosis, a regulated and immunogenic form of necrotic cell death, is implicated in various human diseases, including infection, inflammation, neurodegeneration, and cancer. The tumor necrosis factor (TNF)-induced necroptosis pathway is well-studied, involving the formation of the necrosome comprising receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase-like protein MLKL. The necrosome, localized in cellular membranes, ultimately leads to plasma membrane rupture. However, the recruitment of the necrosome to the membranes remains unclear. To enhance our understanding of necroptosis, we conducted a whole-genome CRISPR knockout screen to identify genes crucial for necroptosis. A prominent hit emerged in Rab27a, a small GTPase associated with vesicle-mediated transport. Initial findings show that the necrosome colocalizes with Rab27a during necroptosis induction. Importantly, Rab27a knockout significantly reduces necroptosis by decreasing MLKL polymer formation, which is essential for plasma membrane rupture. Ongoing investigations focus on unraveling the mechanism by which Rab27a recruits the necrosome to vesicles and facilitates its transport to other membrane structures, thus promoting necroptosis.