Targeting CMPK2-intervened redox metabolism to mitigate hepatic ischemia-reperfusion injury

HIRI is a major clinical challenge that occurs when blood supply to the liver is temporarily interrupted and then restored, as commonly seen in liver resection and liver transplantation. Current research shows that the injury involves oxidative stress, mitochondrial dysfunction, metabolic imbalance, and excessive inflammation. Although strategies such as reducing ischemic time, ischemic preconditioning, antioxidants, and mitochondrial protectants have been explored, their protective effects remain limited. A key unresolved problem is how mitochondrial lipid metabolism, mtDNA-centered oxidative stress, and inflammatory signaling interact to amplify liver injury.

A study (DOI: 10.48130/targetome-0026-0011) published in Targetome on 31 March 2026 by Xiaojiaoyang Li's team, Beijing University of Chinese Medicine, reports that ACT protects against HIRI by suppressing CMPK2-driven mitochondrial redox dysregulation and blocking the lipotoxicity-oxidative stress-inflammation cycle.

To define the role of CMPK2 and the protective mechanism of ACT, the researchers combined animal models, cell models, sequencing analysis, and molecular biology experiments. In mice, they established a 70% hepatic ischemia model followed by reperfusion and treated animals with different doses of ACT, using N-acetylcysteine as a positive control. They also constructed a hepatocyte-specific CMPK2 overexpression model to test whether CMPK2 was essential for ACT-mediated protection. In vitro, AML12 hepatocytes were exposed to hypoxia/reoxygenation to mimic ischemia-reperfusion stress, followed by ACT treatment, gene silencing, recombinant protein stimulation, and mtDNA transfection. RNA sequencing of whole liver tissue and isolated hepatocytes showed that HIRI strongly altered pathways related to ATP synthesis, lipid metabolism, mitochondrial electron transport, apoptosis, and inflammation. ACT reversed many of these transcriptional changes. Further analysis identified CMPK2 and MYD88 as shared critical targets. The team found that HIRI increased acyl-CoA thioesterase 2 (ACOT2), promoting free fatty acid accumulation in mitochondria. This lipid overload enhanced ROS production and weakened mitochondrial oxidative metabolism. ACT reduced ACOT2 expression, lowered free fatty acid levels, restored fatty acid β-oxidation-related genes, increased ATP production, and improved mitochondrial complex I and IV activities. The researchers then examined mtDNA-related oxidative injury. HIRI and hypoxia/reoxygenation increased CMPK2 expression, mtDNA synthesis, oxidized mtDNA accumulation, mitochondrial permeability transition pore opening, and mtDNA release. Released mtDNA activated the TLR9-MYD88-NF-κB pathway, which promoted nuclear translocation of interferon regulatory factor 1 (IRF1). IRF1 further stimulated the transcription of Cmpk2 and Duox2, creating a damaging feedback loop that intensified ROS generation and inflammatory signaling. ACT disrupted this cycle by inhibiting IRF1 nuclear translocation, reducing Cmpk2 and Duox2 transcription, and limiting mtDNA leakage. Binding assays, including DARTS, CETSA, SPR, and MST, further suggested that ACT can directly interact with CMPK2 and promote its mitophagy-dependent degradation. Importantly, hepatocyte-specific CMPK2 overexpression weakened the protective effects of ACT, confirming CMPK2 as a central therapeutic target.

Overall, the study establishes CMPK2 as a pivotal regulator linking mitochondrial lipid metabolism, redox imbalance, mtDNA release, and inflammatory activation in HIRI. By targeting CMPK2 and the TLR9-IRF1-CMPK2/DUOX2-mtDNA axis, ACT provides a mechanistic basis for developing new interventions to reduce liver injury associated with transplantation and major hepatic surgery.