MLKL deficiency attenuated hepatocyte oxidative DNA damage by activating mitophagy to suppress macrophage cGAS-STING signaling during liver ischemia and reperfusion injury

Abstract

Mixed-lineage kinase domain-like protein (MLKL)-mediated necroptosis has been implicated in aggravating liver ischemia and reperfusion (IR) injury. However, the precise role and mechanism of MLKL in regulating oxidative DNA damage of hepatocytes and subsequent activation of macrophage stimulator of interferon genes (STING) signaling remains unclear. In this study, we investigated the role of MLKL in regulating the interplay between hepatocyte injury and macrophage pro-inflammatory responses during liver IR injury. We found that IR increased MLKL expression in liver tissues of wild type (WT) mice. MLKL knockout (KO) attenuated liver IR injury and suppressed the activation of cGAS-STING signaling in intrahepatic macrophages, which was abrogated by STING activation with its agonist. Mechanistically, IR induced oxidative DNA damage in hepatocytes, leading to cGAS-STING activation in macrophages, which was suppressed by MLKL KO. Moreover, increased PTEN-induced kinase 1 (PINK1)-mediated mitophagy contributed to reduced oxidative DNA damage in hepatocytes and subsequent decreased activation of STING signaling in macrophages in MLKL KO mice. Our findings demonstrated a non-canonical role of MLKL in the pathogenesis of liver IR. MLKL deficiency significantly promoted PINK1-mediated mitophagy activation to inhibit oxidative DNA damage in hepatocytes, which in turn suppressed macrophage cGAS-STING activation and inflammatory liver IR injury.

Cell Death in Liver Disease and Liver Surgery

“…Furthermore, it exacerbates liver damage after IRI in aging mice [ 213 ]. Mechanistically, MLKL deficiency may promote PTEN-induced kinase 1 (PINK1)-mediated mitophagy activation, inhibiting oxidative DNA damage in hepatocytes, which in turn suppresses macrophage cGAS-STING activation and inflammatory liver IRI [ 214 ]. Underlining the importance of necroptosis as a mediator of intercellular crosstalk, it is suggested that MLKL-mediated hepatocyte necroptosis is controlled by the Notch pathway in macrophages [ 215 ].…”

cGAS–STING pathway in ischemia-reperfusion injury: a potential target to improve transplantation outcomes

“…Furthermore, kidney IRI increases receptor-interacting protein 3 levels to facilitate mtDNA damage and leakage and then activates the cGAS–STING–p65 pathway by promoting cytosolic mtDNA expression and increases the transcription of pro-inflammatory factors ( 57 ). In contrast, mixed lineage kinase domain like (MLKL) pseudokinase knockout significantly enhances PTEN-induced kinase 1-mediated mitophagy activation to alleviate oxidative stress in hepatocytes, thereby inhibiting macrophage cGAS–STING activation and liver IRI ( 58 ). These make mtDNA an important target for inhibiting cGAS–STING pathway activation.…”

Extracellular Vesicles Containing GAS6 Protect the Liver from Ischemia-Reperfusion Injury by Enhancing Macrophage Efferocytosis via MerTK-ERK-COX2 Signaling

“…Additionally, bridging molecules like growth arrest-speci c 6 (GAS6) or milk fat globule epidermal growth factor-factor VIII facilitate e cient removal of dying cells [9][10] [11]. Recent research has highlighted how GAS6-Mer interaction can offer both anti-in ammatory and pro-survival effects against HIRI [12][13] [14], underscoring the signi cance of targeting phagocytic signaling for mitigating liver injury.…”