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Genetic or nutritional disorders in homocysteine or folate metabolism increase protein N-homocysteinylation in mice.


Genetic disorders of homocysteine (Hcy) or folate metabolism or high-methionine diets elevate plasma Hcy and its atherogenic metabolite Hcy-thiolactone. In humans, severe hyperhomocysteinemia due to genetic alterations in cystathionine beta-synthase (Cbs) or methylenetetrahydrofolate reductase (Mthfr) results in neurological abnormalities and premature death from vascular complications. In mouse models, dietary or genetic hyperhomocysteinemia results in liver or brain pathological changes and accelerates atherosclerosis. Hcy-thiolactone has the ability to form isopeptide bonds with protein lysine residues, which generates modified proteins (N-Hcy-protein) with autoimmunogenic and prothrombotic properties. Our aim was to determine how N-Hcy-protein levels are affected by genetic or nutritional disorders in Hcy or folate metabolism in mice. We found that plasma N-Hcy-protein was elevated 10-fold in mice fed a high-methionine diet compared with the animals fed a normal commercial diet. We also found that inactivation of Cbs, Mthfr, or the proton-coupled folate transporter (Pcft) gene resulted in a 10- to 30-fold increase in plasma or serum N-Hcy-protein levels. Liver N-Hcy-protein was elevated 3.4-fold in severely and 11-fold in extremely hyperhomocysteinemic Cbs-deficient mice, 3.6-fold in severely hyperhomocysteinemic Pcft mice, but was not elevated in mildly hyperhomocysteinemic Mthfr-deficient animals, suggesting that mice have a capacity to prevent accumulation of N-Hcy-protein in their organs. These findings provide evidence that N-Hcy-protein is an important metabolite associated with Hcy pathophysiology in the mouse.

Pubmed ID: 19204075


  • Jakubowski H
  • Perla-Kaj├ín J
  • Finnell RH
  • Cabrera RM
  • Wang H
  • Gupta S
  • Kruger WD
  • Kraus JP
  • Shih DM


FASEB journal : official publication of the Federation of American Societies for Experimental Biology

Publication Data

June 2, 2009

Associated Grants

  • Agency: NHLBI NIH HHS, Id: R01 HL067033
  • Agency: NHLBI NIH HHS, Id: R01 HL067033-08
  • Agency: NHLBI NIH HHS, Id: R01 HL077288
  • Agency: NHLBI NIH HHS, Id: R01 HL077288-06
  • Agency: NHLBI NIH HHS, Id: R01 HL082774
  • Agency: NHLBI NIH HHS, Id: R01 HL082774-04
  • Agency: NHLBI NIH HHS, Id: R01 HL117654

Mesh Terms

  • Animals
  • Cystathionine beta-Synthase
  • Diet
  • Folic Acid
  • Homocysteine
  • Humans
  • Hyperhomocysteinemia
  • Liver
  • Membrane Transport Proteins
  • Methionine
  • Methylenetetrahydrofolate Reductase (NADPH2)
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout