Transcriptional Regulation of the Albumin Gene Depends on the Removal of Histone Methylation Marks by the FAD-Dependent Monoamine Oxidase Lysine-Specific Demethylase 1 in HepG2 Human Hepatocarcinoma Cells

Abstract

Lysine-specific demethylase (LSD) 1 is an FAD-dependent demethylase that catalyzes the removal of methyl groups from lysine-4 in histone H3, thereby mediating gene repression. Here we tested the hypothesis that riboflavin deficiency causes a loss of LSD1 activity in HepG2 human hepatocarcinoma cells, leading to an accumulation of lysine-4-dimethylated histone H3 (H3K4me2) marks in the albumin promoter and aberrant upregulation of albumin expression. Cells were cultured in riboflavin-defined media providing riboflavin at concentrations representing moderately deficient (3.1 nmol/L), sufficient (12.6 nmol/L), and supplemented (301 nmol/L) cells in humans for 7 d. The efficacy of treatment was confirmed by assessing glutathione reductase activity and concentrations of reduced glutathione as markers of riboflavin status. LSD activity was 21% greater in riboflavin-supplemented cells compared with riboflavin-deficient and -sufficient cells. The loss of LSD activity was associated with a gain in the abundance of H3K4me2 marks in the albumin promoter; the abundance of H3K4me2 marks was ∼170% higher in riboflavin-deficient cells compared with sufficient and supplemented cells. The abundance of the repression mark, K9-trimethylated histone H3, was 38% lower in the albumin promoter of riboflavin-deficient cells compared with the other treatment groups. The expression of albumin mRNA was aberrantly increased by 200% in riboflavin-deficient cells compared with sufficient and supplemented cells. In conclusion, riboflavin deficiency impairs gene regulation by epigenetic mechanisms, mediated by a loss of LSD1 activity.

Compartmentation of Metabolites in Regulating Epigenomes of Cancer

“…The second factor is that cancer cells have a higher rate of one carbon metabolism (47) as well as a higher amount of folate-cycle cells was found to influence the activity of lysine (K)-specific demethylase 1A (LSD1) and to result in a global increase of H3K4 mono-or demethylation (76). Similar results were also identified in human hepatocarcinoma cells by the same group (77). In adipocytes, the availability of FAD was also found to be critical to LSD1 activity in regulating the genes that contribute to cellular energy expenditure (78).…”

Low activity of LSD1 elicits a pro-inflammatory gene expression profile in riboflavin-deficient human T Lymphoma Jurkat cells

“…Importantly, in a recent publication, we expanded that point of view and demonstrated that FAD-dependent demethylation events, mediated by LSD1, cause an aberrant increase in the expression of albumin in human liver cells (Liu and Zempleni 2014). That publication established a rationale for further studies of the importance of FAD-dependent LSD1 in gene regulation.…”

Identification of Differentially-Methylated Genes and Pathways in Patients with Delayed Cerebral Ischemia Following Subarachnoid Hemorrhage

“…Suarez et al 36) showed a neuroprotective effect of 25% human ALB with dosage of 1.25 g/kg/day compared to 0.625 g/kg/day (OR, 3.0513; 95% CI, 0.6586-14.1367) in patients with SAH. The expression of ALB mRNA was increased in riboflavin-deficient cells by a loss of lysine-specific demethylase 1 activity and the subsequent accumulation of lysine-4-demethylated histone H3 marks in the promoter of ALB in human hepatocarcinoma cells 22) . Undermethylation of the 5' end of the ALB gene was required for ALB production in rat hepatoma cells 27) .…”