Burn-induced mitochondrial dysfunction in hepatocytes: The role of methylation-controlled J protein silencing.

Background: Burn injuries trigger a systemic hyperinflammatory response, leading to multiple organ dysfunction, including significant hepatic damage. The liver plays a crucial role in regulating immune responses and metabolism after burn injuries, making it critical to develop strategies to mitigate hepatic impairment. This study investigates the role of methylation-controlled J protein (MCJ), an inner mitochondrial protein that represses complex I in burn-induced oxidative stress and mitochondrial dysfunction, using an in vitro Alpha Mouse Liver 12 cell model.

Methods: Alpha Mouse Liver 12 cells were treated with serum from burn-injured mice (SBIM) to simulate burn injury in vitro. Methylation-controlled J protein was silenced using shRNA. Cell viability, apoptosis markers, reactive oxygen species levels, antioxidant response elements, electron transport chain components, and mitochondrial respiration were assessed using various techniques, including Cell Counting Kit-8 assay, Western blotting, MitoSOX Red staining, and Seahorse XF analysis.

Results: Serum from burn-injured mice treatment (10%) for 8 hours reduced Alpha Mouse Liver 12 cell viability to 50% of control levels and increased MCJ expression fivefold. It also significantly upregulated apoptosis markers: cleaved caspase-3 (4-fold), Bax (3.8-fold), and cytosolic cytochrome c (3.5-fold). Methylation-controlled J protein silencing improved cell viability to 85% of control levels and reduced apoptosis markers by 75% to 78%. Serum from burn-injured mice increased reactive oxygen species levels by 3-fold, while MCJ silencing reduced this by 2.5-fold. Antioxidant proteins (NRF2, HO-1, NQO-1, GCLC, catalase) were suppressed by SBIM but upregulated 3.2- to 3.8-fold with MCJ silencing. Serum from burn-injured mice reduced electron transport chain components (NDUFS1, SDHB, MTCO2) by 45% to 65%, which MCJ silencing restored 2.5- to 3-fold. Mitochondrial respiration improved significantly with MCJ silencing: basal respiration (+26%), maximal respiration (+66%), adenosine triphosphate production (+25%), and spare respiratory capacity (+63%).

Conclusion: Methylation-controlled J protein plays a critical role in burn-induced hepatocyte damage. Its silencing alleviates SBIM-induced cytotoxicity, oxidative stress, and mitochondrial dysfunction. These findings highlight MCJ as a potential therapeutic target for preserving liver function in burn patients, warranting further in vivo studies to explore its clinical potential.