The Hepatic Transcriptomes of Two Mouse Models of Liver Fibrosis Reveal Shared Molecular Patterns Associated with a Common Dysregulation of Folate Metabolism.

Abstract

BACKGROUND: Dysregulated one-carbon metabolism occurs in metabolic dysfunction-associated steatotic liver disease (MASLD) and in models of liver fibrosis, but two fibrosis models display opposing methylation cycle profiles, which has been a point of confusion. Broader changes in one-carbon related metabolism and the consequent impact on transcriptional events have not been fully explored. OBJECTIVE: The objective of this study was to identify common metabolic and transcriptional profiles in methionine and choline deficient (MCD) and glycine N-methyltransferase knockout (GNMTKO) mice to help us understand molecular mechanisms that contribute to hepatic fibrosis. METHODS: Eight-wk-old male GNMTKO (C57BL6J background) and control mice were fed AIN-76 based diet (24% casein, 60% sucrose/starch, and 5% fat) for 8 wk (n = 5-6). Ten-wk-old male C57BL6J mice were fed amino acid-defined diet (based on AIN-76) with or without sufficient methionine and choline (65% sucrose/starch, 15% defined amino acid, and 10% fat) for 5 wk (n = 6). We characterized the expression of folate metabolic enzymes, measured the amino acid content in plasma and liver, performed targeted metabolomics and RNA sequencing in liver to compare metabolite and transcriptional profiles. RESULTS: We measured an 11-fold increase (P = 0.0067) in MTHFD1L1 and 2.8-fold (P = 0.013) MTHFS expression in liver of GNMTKO mice, matching results from our previous study in MCD mice. Liver mitochondria from GNMTKO mice had a 2-fold (P = 0.0423) higher capacity for oxidation of one-carbon units. We find common regulation of xenobiotic/metabolic sensors, growth, immune, and inflammatory pathways in our transcriptomic analysis. Statistical analysis was performed using an unpaired Student's t-test with Welch's correction, and RNA sequencing data were analyzed using the method of Benjamini-Hochberg. CONCLUSIONS: We identify a common dysregulation in folate metabolism in two widely used rodent models of liver fibrosis and highlight the consequent metabolic disturbances. Analysis of hepatic transcriptional profiles of MCD and GNMTKO mice reveals novel association of the transcriptional regulators STAT5b, AhR, and ARNT with liver fibrosis.