1. Academic Validation
  2. IQGAP1 promotes mitochondrial damage and activation of the mtDNA sensor cGAS-STING pathway to induce endothelial cell pyroptosis leading to atherosclerosis

IQGAP1 promotes mitochondrial damage and activation of the mtDNA sensor cGAS-STING pathway to induce endothelial cell pyroptosis leading to atherosclerosis

  • Int Immunopharmacol. 2023 Aug 17;123:110795. doi: 10.1016/j.intimp.2023.110795.
Cheng An 1 Fei Sun 1 Can Liu 1 Shaojun Huang 1 Tao Xu 2 Chengxin Zhang 3 Shenglin Ge 4
Affiliations

Affiliations

  • 1 Department of Cardiovascular Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, China.
  • 2 Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, Anhui 230032, China.
  • 3 Department of Cardiovascular Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, China. Electronic address: zhangchengxin@ahmu.edu.cn.
  • 4 Department of Cardiovascular Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, China. Electronic address: geshenglin@ahmu.edu.cn.
Abstract

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.

Keywords

Atherosclerosis; IQGAP1; MtDNA sensors; Oxidative stress; Pyroptosis.

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