Intracellular S-adenosylhomocysteine concentrations predict global DNA hypomethylation in tissues of methyl-deficient cystathionine beta-synthase heterozygous mice.

Because S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are the substrate and product of essential methyltransferase reactions; the ratio of SAM:SAH is frequently used as an indicator of cellular methylation potential. However, it is not clear from the ratio whether substrate insufficiency, product inhibition or both are required to negatively affect cellular methylation capacity. A combined genetic and dietary approach was used to modulate intracellular concentrations of SAM and SAH. Wild-type (WT) or heterozygous cystathionine beta-synthase (CBS +/-) mice consumed a control or methyl-deficient diet for 24 wk. The independent and combined effect of genotype and diet on SAM, SAH and the SAM:SAH ratio were assessed in liver, kidney, brain and testes and were correlated with relative changes in tissue-specific global DNA methylation. The combined results from the different tissues indicated that a decrease in SAM alone was not sufficient to affect DNA methylation in this model, whereas an increase in SAH, either alone or associated with a decrease in SAM, was most consistently associated with DNA hypomethylation. A decrease in SAM:SAH ratio was predictive of reduced methylation capacity only when associated with an increase in SAH; a decrease in the SAM:SAH ratio due to SAM depletion alone was not sufficient to affect DNA methylation in this model. Plasma homocysteine levels were positively correlated with intracellular SAH levels in all tissues except kidney. These results support the possibility that plasma SAH concentrations may provide a sensitive biomarker for cellular methylation status.

[1]  G. Varela-Moreiras,et al.  Carbon tetrachloride–induced hepatic injury is associated with global DNA hypomethylation and homocysteinemia: Effect of S‐adenosylmethionine treatment , 1995, Hepatology.

[2]  E. Mosharov,et al.  The quantitatively important relationship between homocysteine metabolism and glutathione synthesis by the transsulfuration pathway and its regulation by redox changes. , 2000, Biochemistry.

[3]  J. Finkelstein,et al.  Methionine metabolism in mammals: regulatory effects of S-adenosylhomocysteine. , 1974, Archives of biochemistry and biophysics.

[4]  J. Mason,et al.  Genomic DNA hypomethylation, a characteristic of most cancers, is present in peripheral leukocytes of individuals who are homozygous for the C677T polymorphism in the methylenetetrahydrofolate reductase gene. , 2000, Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology.

[5]  P. Ueland,et al.  Cystathionine β-Synthase Deficiency: Metabolic Aspects , 1997 .

[6]  Cantoni Gl.  The role of S-adenosylhomocysteine in the biological utilization of S-adenosylmethionine. , 1985 .

[7]  L. Poirier,et al.  Tissue levels of S-adenosylmethionine and S-adenosylhomocysteine in rats fed methyl-deficient, amino acid-defined diets for one to five weeks. , 1983, Carcinogenesis.

[8]  Peter W. Laird,et al.  THE ROLE OF DNA METHYLATION IN CANCER GENETICS AND EPIGENETICS , 1996 .

[9]  I. Pogribny,et al.  A sensitive new method for rapid detection of abnormal methylation patterns in global DNA and within CpG islands. , 1999, Biochemical and biophysical research communications.

[10]  J F Gregory,et al.  Polymorphisms of methylenetetrahydrofolate reductase and other enzymes: metabolic significance, risks and impact on folate requirement. , 1999, The Journal of nutrition.

[11]  W. Haefeli,et al.  Low whole-blood S-adenosylmethionine and correlation between 5-methyltetrahydrofolate and homocysteine in coronary artery disease. , 1996, Arteriosclerosis, thrombosis, and vascular biology.

[12]  W. Haefeli,et al.  Disturbed ratio of erythrocyte and plasma S-adenosylmethionine/S-adenosylhomocysteine in peripheral arterial occlusive disease. , 2001, Atherosclerosis.

[13]  M. Brosnan,et al.  Renal uptake and excretion of homocysteine in rats with acute hyperhomocysteinemia. , 1998, Kidney international.

[14]  J. Christman,et al.  Rapid appearance of hypomethylated DNA in livers of rats fed cancer-promoting, methyl-deficient diets. , 1989, Cancer research.

[15]  I. Pogribny,et al.  Moderate folate depletion increases plasma homocysteine and decreases lymphocyte DNA methylation in postmenopausal women. , 1998, The Journal of nutrition.

[16]  B. Vester,et al.  High Performance Liquid Chromatography Method for Rapid and Accurate Determination of Homocysteine in Plasma and Serum , 1991, European journal of clinical chemistry and clinical biochemistry : journal of the Forum of European Clinical Chemistry Societies.

[17]  L. Poirier,et al.  Methyl groups in carcinogenesis: effects on DNA methylation and gene expression. , 1992, Cancer research.

[18]  O. Z. Sellinger,et al.  Species and tissue differences in the catabolism of S-adenosyl-L-homocysteine: a quantitative, chromatographic study. , 1977, Life sciences.

[19]  J. Selhub,et al.  Folate-deficiency-induced homocysteinaemia in rats: disruption of S-adenosylmethionine's co-ordinate regulation of homocysteine metabolism. , 1994, The Biochemical journal.

[20]  L. Bailey,et al.  Folate metabolism and requirements. , 1999, The Journal of nutrition.

[21]  G. Omenn,et al.  A quantitative assessment of plasma homocysteine as a risk factor for vascular disease. Probable benefits of increasing folic acid intakes. , 1995, JAMA.

[22]  R. Borchardt,et al.  Pancreatic exocrine secretion is blocked by inhibitors of methylation. , 1997, Archives of biochemistry and biophysics.

[23]  N. Maeda,et al.  Mice deficient in cystathionine beta-synthase: animal models for mild and severe homocyst(e)inemia. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[24]  G. Rampersaud,et al.  Genomic DNA methylation decreases in response to moderate folate depletion in elderly women. , 2000, The American journal of clinical nutrition.

[25]  I. Pogribny,et al.  Alterations in hepatic p53 gene methylation patterns during tumor progression with folate/methyl deficiency in the rat. , 1997, Cancer letters.

[26]  I. Pogribny,et al.  Measurement of Plasma and Intracellular S–Adenosylmethionine and S–Adenosylhomocysteine Utilizing Coulometric Electrochemical Detection: Alterations with Plasma Homocysteine and Pyridoxal 5'–Phosphate. Concentrations , 2000 .

[27]  J. Finkelstein,et al.  Pathways and Regulation of Homocysteine Metabolism in Mammals , 2000, Seminars in thrombosis and hemostasis.

[28]  F. Corrales,et al.  Interaction of liver methionine adenosyltransferase with hydroxyl radical , 1997, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[29]  T. Perry,et al.  Sulfur-containing amino acids in the plasma and urine of homocystinurics. , 1967, Clinica chimica acta; international journal of clinical chemistry.

[30]  J. Mason,et al.  Folate and carcinogenesis: an integrated scheme. , 2000, The Journal of nutrition.

[31]  I. Pogribny,et al.  Increase in Plasma Homocysteine Associated with Parallel Increases in Plasma S-Adenosylhomocysteine and Lymphocyte DNA Hypomethylation* , 2000, The Journal of Biological Chemistry.

[32]  P. Chiang,et al.  Perturbation of biochemical transmethylations by 3-deazaadenosine in vivo. , 1979, Biochemical pharmacology.

[33]  S. Vollset,et al.  The controversy over homocysteine and cardiovascular risk. , 2000, The American journal of clinical nutrition.

[34]  T. Eskes.  Neural tube defects, vitamins and homocysteine , 1998, European Journal of Pediatrics.

[35]  Shelly C. Lu,et al.  Changes in methionine adenosyltransferase and S-adenosylmethionine homeostasis in alcoholic rat liver. , 2000, American journal of physiology. Gastrointestinal and liver physiology.

[36]  V. L. Wilson,et al.  Abnormal folate metabolism and mutation in the methylenetetrahydrofolate reductase gene may be maternal risk factors for Down syndrome. , 1999, The American journal of clinical nutrition.

[37]  W. Coulson,et al.  Male rats fed methyl- and folate-deficient diets with or without niacin develop hepatic carcinomas associated with decreased tissue NAD concentrations and altered poly(ADP-ribose) polymerase activity. , 1997, The Journal of nutrition.

[38]  R. F. Huang,et al.  Folate depletion and elevated plasma homocysteine promote oxidative stress in rat livers. , 2001, The Journal of nutrition.

[39]  Shirley A. Miller,et al.  A simple salting out procedure for extracting DNA from human nucleated cells. , 1988, Nucleic acids research.

[40]  E. Gunter,et al.  Rapid and accurate HPLC assay for plasma total homocysteine and cysteine in a clinical laboratory setting. , 1999, Clinical chemistry.

[41]  G. Young,et al.  Ability of endogenous folate from soy protein isolate to maintain plasma homocysteine and hepatic DNA methylation during methyl group depletion in rats. , 1998, Journal of nutritional science and vitaminology.

[42]  L. Gaspa,et al.  Correlation between S-adenosyl-L-methionine content and production of c-myc, c-Ha-ras, and c-Ki-ras mRNA transcripts in the early stages of rat liver carcinogenesis. , 1994, Cancer letters.

[43]  D. Hoffman,et al.  Relationship between tissue levels of S-adenosylmethionine, S-adenylhomocysteine, and transmethylation reactions. , 1979, Canadian journal of biochemistry.

[44]  B. Hultberg,et al.  Plasma homocysteine in renal failure. , 1993, Clinical nephrology.

[45]  J. Finkelstein,et al.  Methionine metabolism in mammals. , 1990, The Journal of nutritional biochemistry.

[46]  M. Pajares,et al.  S-adenosylmethionine synthesis: molecular mechanisms and clinical implications. , 1997, Pharmacology & therapeutics.

[47]  D. Marion,et al.  S-Adenosylmethionine and S-adenosylhomocystein metabolism in isolated rat liver. Effects of L-methionine, L-homocystein, and adenosine. , 1980, The Journal of biological chemistry.

[48]  M. Brosnan,et al.  Characterization of homocysteine metabolism in the rat liver. , 2000, The Biochemical journal.