Mutations in methylenetetrahydrofolate reductase or cystathionine beta-synthase gene, or a high-methionine diet, increase homocysteine thiolactone levels in humans and mice.

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Chwatko G, Boers GH, Strauss KA, Shih DM, Jakubowski H

Mutations in methylenetetrahydrofolate reductase or cystathionine beta-synthase gene, or a high-methionine diet, increase homocysteine thiolactone levels in humans and mice.

FASEB J. 2007 Jun;21(8):1707-13. Epub 2007 Feb 27.

PubMed ID

17327360 [ View in PubMed

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Abstract

Genetic disorders of homocysteine (Hcy) metabolism or a high-methionine diet lead to elevations of plasma Hcy levels. In humans, severe genetic hyperhomocysteinemia results in premature death from vascular complications whereas dietary hyperhomocysteinemia is often used to induce atherosclerosis in animal models. Hcy is mistakenly selected in place of methionine by methionyl-tRNA synthetase during protein biosynthesis, which results in the formation of Hcy-thiolactone and initiates a pathophysiological pathway that has been implicated in human vascular disease. However, whether genetic deficiencies in Hcy metabolism or a high-methionine diet affect Hcy-thiolactone levels in mammals has been unknown. Here we show that plasma Hcy-thiolactone is elevated 59-fold and 72-fold in human patients with hyperhomocysteinemia secondary to mutations in methylenetetrahydrofolate reductase and cystathionine beta-synthase genes, respectively. We also show that mice, like humans, eliminate Hcy-thiolactone by urinary excretion; in contrast to humans, however, mice also eliminate significant amounts of plasma total Hcy (approximately 38%) by urinary excretion. In mice, hyperhomocysteinemia secondary to a high-methionine diet leads to 3.7-fold and 25-fold increases in plasma and urinary Hcy-thiolactone levels, respectively. Thus, we conclude that hyperhomocysteinemia leads to significant increases in the atherogenic metabolite Hcy-thiolactone in humans and mice.

DrugBank Data that Cites this Article

Drug Enzymes

Drug	Enzyme	Kind	Organism	Pharmacological Action	Actions
Methionine	Methionine--tRNA ligase, cytoplasmic	Protein	Humans	Unknown	Substrate	Details