Department of Cardiovascular Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, China.
Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui 230032, China.
Int Immunopharmacol. 2023 Oct;123:110795. doi: 10.1016/j.intimp.2023.110795. Epub 2023 Aug 17.
Atherosclerosis (AS) is the most common cardiovascular disease and has limited therapeutic options. IQ motif-containing GTPase-activating protein 1 (IQGAP1) is an important scaffolding protein regulating mitochondrial function influencing endothelial cell activity. Evidence suggests that mitochondrial damage can lead to leakage of mtDNA into the cytoplasm to activate the DNA sensor cGAS-STING to mediate pyroptosis. However, whether IQGAP1 induces NLRP3-mediated endothelial cell pyroptosis by regulating mitochondrial function and activating the DNA sensor cGAS-STING, and its underlying mechanisms remain unclear. In vivo, ApoE C57BL/J and Ldlr C57BL/J mice were pre-injected with adeno-associated virus (AAV) by the tail vein to specifically silence IQGAP1 expression and were fed a high-fat diet (HFD) for 12 weeks. IQGAP1 knockdown reduced mtDNA release and decreased the expression of DNA receptors and pyroptosis-related molecules as determined by immunohistochemistry and immunofluorescence. In vitro, palmitic acid (0.3 mmol/L) was incubated with human umbilical vein endothelial cells (HUVECs) for 24 h. Overexpression of IQGAP1 in HUVECs, flow cytometry, and mitochondrial superoxide staining revealed increased levels of ROS. Moreover, the mitochondrial tracker with dsDNA co-localization showed the release of mtDNA into the cytoplasm increased, which activated the DNA receptor cGAS-STING. Protein blotting and TUNEL staining revealed that IQGAP1 promoted NLRP3-mediated pyroptosis. Furthermore, cGAS or STING small-molecule inhibitors RU.521 or C-176 reverse IQGAP1-promoted HUVECs from undergoing NLRP3-mediated pyroptosis. These results suggest that IQGAP1 promotes oxidative stress and mtDNA release, activates the DNA sensor cGAS-STING, and leads to NLRP3-mediated pyroptosis. The present study provides new insights into the mechanisms underlying AS and identifies new pharmacological targets for treatment.
动脉粥样硬化（AS）是最常见的心血管疾病，治疗选择有限。富含 IQ 基序的 GTP 酶激活蛋白 1（IQGAP1）是一种重要的支架蛋白，可调节影响内皮细胞活性的线粒体功能。有证据表明，线粒体损伤可导致 mtDNA 漏入细胞质，激活 DNA 传感器 cGAS-STING，从而介导细胞焦亡。然而，IQGAP1 是否通过调节线粒体功能和激活 DNA 传感器 cGAS-STING 诱导 NLRP3 介导的内皮细胞细胞焦亡，其潜在机制尚不清楚。在体内，通过尾静脉预先注射腺相关病毒（AAV）以特异性沉默 IQGAP1 表达，并用高脂肪饮食（HFD）喂养 ApoE C57BL/J 和 Ldlr C57BL/J 小鼠 12 周。免疫组化和免疫荧光法检测到 IQGAP1 敲低可减少 mtDNA 释放并降低 DNA 受体和细胞焦亡相关分子的表达。在体外，用 0.3mmol/L 的棕榈酸孵育人脐静脉内皮细胞（HUVEC）24 小时。在 HUVEC 中转染 IQGAP1 过表达，流式细胞术和线粒体超氧化物染色显示 ROS 水平升高。此外，与 dsDNA 共定位的线粒体示踪剂显示 mtDNA 释放到细胞质中增加，从而激活 DNA 受体 cGAS-STING。蛋白印迹和 TUNEL 染色显示 IQGAP1 促进 NLRP3 介导的细胞焦亡。此外，cGAS 或 STING 小分子抑制剂 RU.521 或 C-176 逆转 IQGAP1 促进的 HUVEC 发生 NLRP3 介导的细胞焦亡。这些结果表明，IQGAP1 促进氧化应激和 mtDNA 释放，激活 DNA 传感器 cGAS-STING，并导致 NLRP3 介导的细胞焦亡。本研究为 AS 的发病机制提供了新的见解，并确定了新的治疗靶点。
