Rationale: The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) promotes pathological mitochondrial fission during septic acute kidney injury. The mitochondrial open reading frame of the 12S rRNA type-c (MOTS-c) is a mitochondria-derived peptide that exhibits anti-inflammatory properties during cardiovascular illnesses. We explored whether endotoxemia-induced myocardial microvascular injury involved DNA-PKcs and MOTS-c dysregulation./nMethods: To induce endotoxemia in vivo, endothelial cell-specific DNA-PKcs-knockout mice were injected intraperitoneally with a single dose of lipopolysaccharide (10 mg/kg) and evaluated after 72 h./nResults: Lipopolysaccharide exposure increased DNA-PKcs activity in cardiac microvascular endothelial cells, while pharmacological inhibition or endothelial cell-specific genetic ablation of DNA-PKcs reduced lipopolysaccharide-induced myocardial microvascular dysfunction. Proteomic analyses showed that endothelial DNA-PKcs ablation primarily altered mitochondrial protein expression. Verification assays confirmed that DNA-PKcs drastically repressed MOTS-c transcription by inducing mtDNA breaks via pathological mitochondrial fission. Inhibiting MOTS-c neutralized the endothelial protective effects of DNA-PKcs ablation, whereas MOTS-c supplementation enhanced endothelial barrier function and myocardial microvascular homeostasis under lipopolysaccharide stress. In molecular studies, MOTS-c downregulation disinhibited c-Jun N-terminal kinase (JNK), allowing JNK to phosphorylate profilin-S173. Inhibiting JNK or transfecting cells with a profilin phosphorylation-defective mutant improved endothelial barrier function by preventing F-actin depolymerization and lamellipodial degradation following lipopolysaccharide treatment./nConclusions: DNA-PKcs inactivation during endotoxemia could be a worthwhile therapeutic strategy to restore MOTS-c expression, prevent JNK-induced profilin phosphorylation, improve F-actin polymerization, and enhance lamellipodial integrity, ultimately ameliorating endothelial barrier function and reducing myocardial microvascular injury.

中文翻译：

---

DNA依赖性蛋白激酶催化亚基通过破坏MOTS-c/JNK通路并诱导profilin介导的板状伪足降解，加剧内毒素血症引起的心肌微血管损伤

理由： DNA 依赖性蛋白激酶催化亚基 (DNA-PKcs) 在脓毒性急性肾损伤期间促进病理性线粒体裂变。12S rRNA c 型 (MOTS-c) 的线粒体开放阅读框是一种线粒体衍生肽，在心血管疾病期间表现出抗炎特性。我们探讨了内毒素血症诱导的心肌微血管损伤是否涉及 DNA-PKcs 和 MOTS-c 失调。/n方法：为了在体内诱导内毒素血症，内皮细胞特异性DNA-PKcs敲除小鼠腹腔注射单剂量脂多糖（10 mg/kg）并在 72 小时/n 后进行评估结果：脂多糖暴露增加了心脏微血管内皮细胞中的 DNA-PKcs 活性，而DNA-PKcs的药理学抑制或内皮细胞特异性基因消融减少了脂多糖诱导的心肌微血管功能障碍。蛋白质组学分析表明，内皮DNA-PKcs消融主要改变线粒体蛋白表达。验证测定证实，DNA-PKcs通过病理性线粒体裂变诱导 mtDNA 断裂，从而显着抑制MOTS-c转录。抑制MOTS-c中和了DNA-PKcs消融的内皮保护作用，而补充 MOTS-c 则增强了脂多糖应激下的内皮屏障功能和心肌微血管稳态。在分子研究中，MOTS-c 下调会抑制 c-Jun N 末端激酶 (JNK)，从而使 JNK 能够磷酸化 profilin-S173。抑制 JNK 或用 profilin 磷酸化缺陷突变体转染细胞，可通过防止脂多糖治疗后 F-肌动蛋白解聚和板状足降解来改善内皮屏障功能。/n结论：内毒素血症期间 DNA-PKcs 失活可能是恢复 MOTS-c 的一种有价值的治疗策略表达，防止 JNK 诱导的 profilin 磷酸化，改善 F-肌动蛋白聚合，增强板状足完整性，最终改善内皮屏障功能，减少心肌微血管损伤。