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

J Nutr. 2014 Jul;144(7):997-1001. doi: 10.3945/jn.114.192187. Epub 2014 Apr 17.

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.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biomarkers / metabolism
  • Epigenetic Repression
  • Flavin-Adenine Dinucleotide / metabolism*
  • Glutathione / metabolism
  • Glutathione Reductase / metabolism
  • Hep G2 Cells
  • Hepatocytes / enzymology
  • Hepatocytes / metabolism*
  • Histone Demethylases / metabolism*
  • Histones / metabolism*
  • Humans
  • Lysine / metabolism
  • Methylation
  • Monoamine Oxidase / metabolism
  • Osmolar Concentration
  • Promoter Regions, Genetic
  • Protein Processing, Post-Translational*
  • RNA, Messenger / metabolism
  • Riboflavin / metabolism
  • Serum Albumin / genetics
  • Serum Albumin / metabolism*
  • Serum Albumin, Human
  • Transcriptional Activation*

Substances

  • ALB protein, human
  • Biomarkers
  • Histones
  • RNA, Messenger
  • Serum Albumin
  • Flavin-Adenine Dinucleotide
  • Histone Demethylases
  • Monoamine Oxidase
  • KDM1A protein, human
  • Glutathione Reductase
  • Glutathione
  • Lysine
  • Riboflavin
  • Serum Albumin, Human