Department of Biochemistry & Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia.
The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.
Life Sci Alliance. 2023 Mar 28;6(6). doi: 10.26508/lsa.202201735. Print 2023 Jun.
causes severe infections such as pneumonia and sepsis depending on the pore-forming toxin Panton-Valentine leukocidin (PVL). PVL kills and induces inflammation in macrophages and other myeloid cells by interacting with the human cell surface receptor, complement 5a receptor 1 (C5aR1). C5aR1 expression is tighly regulated and may thus modulate PVL activity, although the mechanisms involved remain incompletely understood. Here, we used a genome-wide CRISPR/Cas9 screen and identified F-box protein 11 (FBXO11), an E3 ubiquitin ligase complex member, to promote PVL toxicity. Genetic deletion of FBXO11 reduced the expression of C5aR1 at the mRNA level, whereas ectopic expression of C5aR1 in FBXO11 macrophages, or priming with LPS, restored C5aR1 expression and thereby PVL toxicity. In addition to promoting PVL-mediated killing, FBXO11 dampens secretion of IL-1β after NLRP3 activation in response to bacterial toxins by reducing mRNA levels in a BCL-6-dependent and BCL-6-independent manner. Overall, these findings highlight that FBXO11 regulates C5aR1 and IL-1β expression and controls macrophage cell death and inflammation following PVL exposure.
根据其形成孔的毒素 Panton-Valentine 白细胞毒素（PVL），会引起严重感染，如肺炎和败血症。PVL 通过与人类细胞表面受体，补体 5a 受体 1（C5aR1）相互作用，杀死并引发巨噬细胞和其他髓样细胞的炎症。C5aR1 的表达受到严格调控，因此可能调节 PVL 的活性，尽管涉及的机制仍不完全清楚。在这里，我们使用全基因组 CRISPR/Cas9 筛选，鉴定了 F-box 蛋白 11（FBXO11），一种 E3 泛素连接酶复合物成员，促进 PVL 毒性。FBXO11 的基因缺失降低了 C5aR1 在 mRNA 水平的表达，而 FBXO11 巨噬细胞中 C5aR1 的异位表达，或用 LPS 引发，恢复了 C5aR1 的表达，从而恢复了 PVL 的毒性。除了促进 PVL 介导的杀伤外，FBXO11 还通过 BCL-6 依赖性和 BCL-6 非依赖性方式降低 mRNA 水平，从而减轻 NLRP3 激活后细菌毒素引起的 IL-1β 的分泌，从而减轻 IL-1β 的分泌。总的来说，这些发现强调了 FBXO11 调节 C5aR1 和 IL-1β 的表达，并控制巨噬细胞在暴露于 PVL 后的细胞死亡和炎症。
