HCF-1 as a key modulator of OGT function and O-GlcNAcylation in the liver

Host cell factor-1 (HCF-1) is a transcriptional coregulator essential for maintaining liver function and cellular metabolism. O-linked N-acetylglucosamine transferase (OGT) is a key nutrient-sensing enzyme that catalyzes protein O-GlcNAcylation, a critical post-translational modification regulating metabolic pathways. This study investigates the role of hepatocyte-specific depletion of HCF-1 in regulating OGT stability, activity, and cellular localization in hepatocytes. Using a transgenic mouse model with hepatocyte-specific HCF-1 deletion, we assessed the impact of HCF-1 loss on OGT expression and O-GlcNAcylation activity. OGT protein levels, mRNA expression, and cellular localization were evaluated using molecular and histological techniques. Comparisons were made with control mice and hepatocytes under nutrient-starved conditions. Hepatocyte-specific HCF-1 deletion led to progressive loss of HCF-1 protein and a concomitant decrease in OGT levels and global O-GlcNAcylation. Loss of HCF-1 did not alter OGT mRNA levels, suggesting post-translational regulation. Immunofluorescence revealed reduced nuclear OGT and O-GlcNAcylation, mimicking changes observed under fasting conditions. Isolated HCF-1-deficient hepatocytes showed impaired adhesion, further underscoring HCF-1's role in hepatocyte function. Notably, in heterozygous Hcfc1^{hepKO/ +} females, HCF-1-negative hepatocytes displayed cytoplasmic O-GlcNAcylation, while HCF-1-positive cells maintained nuclear localization. HCF-1 is crucial for regulating OGT stability, activity, and nuclear localization in hepatocytes. These findings establish a mechanistic link between HCF-1 and OGT, highlighting their coordinated role in hepatic nutrient sensing and metabolic regulation.