Uridine diphosphate glucuronosyltransferase 1A1 prevents the progression of liver injury

The liver proteome of individuals with a natural UGT2B17 complete deficiency

Glucuronidation is a crucial pathway for the metabolism and detoxification of drugs and endobiotics, and primarily occurs in the liver. UGT2B17 is one of the 22 glycosyltransferases (UGT) that catalyze this reaction. In a large proportion of the population, UGT2B17 is absent due to complete gene deletion. We hypothesized that a UGT2B17 human deficiency affects the composition and function of the liver proteome, potentially provoking compensatory responses, and altering interconnected pathways and regulatory networks. The objective was to elucidate the liver proteome of UGT2B17-deficient individuals. Liver specimens from UGT2B17-deficient and proficient individuals were compared by mass spectrometry-based proteomics using data-independent acquisition. In UGT2B17-deficient livers, 80% of altered proteins showed increased abundance with a notable enrichment in various metabolic and chemical defense pathways, cellular stress and immune-related responses. Enzymes involved in the homeostasis of steroids, nicotinamide, carbohydrate and energy metabolism, and sugar pathways were also more abundant. Some of these changes support compensatory mechanisms, but do not involve other UGTs. An increased abundance of non-metabolic proteins suggests an adaptation to endoplasmic reticulum stress, and activation of immune responses. Data implies a disrupted hepatocellular homeostasis in UGT2B17-deficient individuals and offers new perspectives on functions and phenotypes associated with a complete UGT2B17 deficiency.

Impaired RelA signaling and lipid metabolism dysregulation in hepatocytes: driving forces in the progression of metabolic dysfunction-associated steatotic liver disease

RelA, also known as nuclear factor kappa B p65, plays a crucial role in the pathogenesis of various liver diseases. However, the specific role of RelA in hepatocytes during the progression of metabolic dysfunction-associated steatotic liver disease (MASLD) is not well understood. This study explored the relationship between impaired RelA signaling and lipid metabolism disorders in hepatocytes, and how they synergistically contribute to the advancement of MASLD. We assessed the changes, regulatory relationships, and impacts of RelA signaling and lipid metabolism remodeling on disease progression both in vitro and in vivo. During MASLD, there was a decrease in the expression of RelA and hepatocyte nuclear factor 1 alpha (HNF1α), with both factors showing mutual enhancement of each other's expression under normal conditions. This synergistic effect was absent during hepatocyte steatosis. RelA or HNF1α depletion in hepatocytes intensified MASLD symptoms, whereas overexpression of RELA or treatment with necrostatin-1 (a necroptosis inhibitor) or Z-VAD (a caspase inhibitor) significantly mitigated these effects. Mechanistically, during hepatic steatosis, altered lipid profiles exhibited lipotoxicity, inducing hepatocyte apoptosis and necroptosis, whereas endoplasmic reticulum (ER) stress triggered lipid remodeling processes similar to those observed in MASLD. RelA signaling upregulated the expression of activating transcription factor 4 and glucose-regulated protein 78, thereby alleviating ER stress. Impaired RelA signaling remodeled the ER stress response and lipid metabolism, and enhanced lipid accumulation and lipid toxicity. In conclusion, impaired RelA signaling and disrupted lipid metabolism form a detrimental feedback loop in hepatocytes that promotes MASLD progression. Lipid accumulation suppresses RelA signaling, remodeling the ER stress response and exacerbating lipid metabolism disorder, ultimately leading to hepatocyte apoptosis and necroptosis.

Targeting uridine diphosphate glucuronosyltransferase 1A1 in liver disease: Current research and future directions

The current letter to the editor pertains to the manuscript entitled 'Uridine diphosphate glucuronosyltransferase 1A1 prevents the progression of liver injury'. Increased levels of uridine diphosphate glucuronosyltransferase 1A1 during liver injury could mitigate damage by reducing endoplasmic reticulum stress, oxidative stress, and dysregulated lipid metabolism, impeding hepatocyte apoptosis and necroptosis.

The cytoplasmic-nuclear transport of DDX3X promotes immune-mediated liver injury in mice regulated by endoplasmic reticulum stress

Immune-mediated liver injury is a common characteristic of various liver diseases, including autoimmune and viral hepatitis. Here, we investigated the role of DEAD-box helicase 3, X-linked (DDX3X) in immune-mediated liver injury. Liver injury was induced in C57BL/6J mice via concanavalin A (Con A). DDX3X hepatocyte-specific knockout (DDX3XΔHep) mice and control (DDX3Xfl/fl) mice were utilized to investigate the role of DDX3X in liver injury. Primary hepatocytes were treated with tunicamycin (TM) to induce ER stress in vitro. The expression of DDX3X in patients with various liver diseases was evaluated. Hepatic DDX3X expression increased, and DDX3X translocated from the cytoplasm to the nucleus during Con A-induced liver injury. DDX3X deficiency ameliorated mouse liver injury and reduced ER stress in liver tissue. The inhibition of ER stress with 4-PBA significantly attenuated liver injury while decreasing DDX3X levels in liver tissue. However, the upregulation of hepatic DDX3X expression reversed Con A-induced liver injury and negated the protective effect of 4-PBA. Mechanistically, the nuclear translocation of DDX3X promoted ER stress-induced apoptosis through the transcriptional induction of CHOP. Moreover, DDX3X was elevated and translocated into the nucleus in patients with HBV-LF and AIH. Additionally, serum DDX3X levels markedly increased in patients with HBV-LF, and a consistent decrease in DDX3X was associated with a good prognosis. The cytoplasmic-to-nuclear translocation of DDX3X promotes ER stress-induced apoptosis, which is an obligatory step that drives hepatic necrosis and tissue damage. Notably, DDX3X is a potential therapeutic target for immune-mediated liver injury.