IL-1β can exit the cytosol as an exosomal cargo following inflammasome activation in intestinal epithelial cells (IECs) in a Gasdermin D (GSDMD)-dependent manner. The mechanistic connection linking inflammasome activation and the biogenesis of exosomes has so far remained largely elusive. Here, we report the Ras GTPase-activating-like protein IQGAP1 functions as an adaptor, bridging GSDMD to the endosomal sorting complexes required for transport (ESCRT) machinery to promote the biogenesis of pro-IL-1β-containing exosomes in response to NLPR3 inflammasome activation. We identified IQGAP1 as a GSDMD-interacting protein through a non-biased proteomic analysis. Functional investigation indicated the IQGAP1-GSDMD interaction is required for LPS and ATP-induced exosome release. Further analysis revealed that IQGAP1 serves as an adaptor which bridges GSDMD and associated IL-1β complex to Tsg101, a component of the ESCRT complex, and enables the packaging of GSDMD and IL-1β into exosomes. Importantly, this process is dependent on an LPS-induced increase in GTP-bound CDC42, a small GTPase known to activate IQGAP1. Taken together, this study reveals IQGAP1 as a link between inflammasome activation and GSDMD-dependent, ESCRT-mediated exosomal release of IL-1β.

中文翻译：

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Ras GTPase 激活样蛋白 IQGAP1 将 Gasdermin D 与 ESCRT 系统连接起来，通过外泌体促进 IL-1β 释放

在肠上皮细胞 (IEC) 中炎症小体以 Gasdermin D (GSDMD) 依赖性方式激活后，IL-1β 可以作为外泌体货物离开细胞质。迄今为止，炎症体激活和外泌体生物发生之间的机制联系在很大程度上仍然难以捉摸。在这里，我们报告了 Ras GTPase 激活样蛋白 IQGAP1 作为适配器，将 GSDMD 桥接至运输 (ESCRT) 机制所需的内体分选复合物，以响应 NLPR3 炎症体促进含有 pro-IL-1β 的外泌体的生物发生激活。我们通过无偏蛋白质组分析将 IQGAP1 鉴定为 GSDMD 相互作用蛋白。功能研究表明 IQGAP1-GSDMD 相互作用是 LPS 和 ATP 诱导的外泌体释放所必需的。进一步的分析表明，IQGAP1 作为一个接头，将 GSDMD 和相关的 IL-1β 复合物桥接到 Tsg101（ESCRT 复合物的一个组成部分），并使 GSDMD 和 IL-1β 包装到外泌体中。重要的是，这个过程依赖于 LPS 诱导的 GTP 结合 CDC42 的增加，CDC42 是一种已知能激活 IQGAP1 的小型 GTP 酶。综上所述，这项研究揭示了 IQGAP1 是炎症小体激活与 GSDMD 依赖性、ESCRT 介导的 IL-1β 外泌体释放之间的联系。