A new high performance liquid chromatographic method for the simultaneous measurement of <i>S</i>‐adenosylmethionine and <i>S</i>‐adenosylhomocysteine concentrations in pig tissues after inactivation of methionine synthase by nitrous oxide

Molloy, Anne M.; Weir, Donald G.; Kennedy, Glenn; Kennedy, S.; Scott, John M.

doi:10.1002/bmc.1130040611

Cited by 37 publications

(12 citation statements)

References 16 publications

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“…The concentrations of choline metabolites were measured by liquid chromatography-electrospray ionization-isotope dilution mass spectrometry as previously described (17). The concentration of AdoMet and S-adenosylhomocysteine (AdoHcy) were measured using the Varian ProStar HPLC system as previously described (18,19) with an Ultrasphere ODS 5-m C18 column, 4.6 ϫ 25 cm (number 235329, Fullerton, CA), and a UV-visible detector (model 118, Gilson, Middleton, WI). Plasma total Hcy (tHcy) and cysteine were measured after derivatizing 50 l of plasma with 7-fluorobenzofurazan-4-sulfonic acid.…”

Section: Generation Of Bhmtmentioning

confidence: 99%

Deletion of Betaine-Homocysteine S-Methyltransferase in Mice Perturbs Choline and 1-Carbon Metabolism, Resulting in Fatty Liver and Hepatocellular Carcinomas

Teng

Mehedint

Garrow

et al. 2011

Journal of Biological Chemistry

189

175

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Betaine-homocysteine S-methyltransferase (BHMT) uses betaine to catalyze the conversion of homocysteine (Hcy) to methionine. There are common genetic polymorphisms in the BHMT gene in humans that can alter its enzymatic activity. We generated the first Bhmt Histopathological analysis revealed that Bhmt ؊/؊ mice developed hepatocellular carcinoma or carcinoma precursors. These results indicate that BHMT has an important role in Hcy, choline, and one-carbon homeostasis. A lack of Bhmt also affects susceptibility to fatty liver and hepatocellular carcinoma. We suggest that functional polymorphisms in BHMT that significantly reduce activity may have similar effects in humans.Betaine-homocysteine S-methyltransferase (BHMT) 2 is a zinc-dependent cytosolic enzyme that catalyzes the transfer of a methyl group from betaine to homocysteine (Hcy) forming dimethylglycine and methionine (Met) (Fig. 5). Humans have common single nucleotide polymorphisms in the BHMT gene that alter BHMT enzyme activity and function (1). A common BHMT single nucleotide polymorphism rs3733890 (41% of NC population has 1 variant allele, and 8% have 2 alleles (2)) was associated with increased risk for having babies with neural tube defects (3), decreased risk for developing cardiovascular disease (4), and reduced risk for breast cancer-specific mortality (5). The epidemiological evidence suggests the importance of single nucleotide polymorphisms in the gene. However, the metabolic consequences of having null mutations of the BHMT gene have not been thoroughly investigated. To directly investigate the role of BHMT in vivo, we generated and characterized mice in which the gene encoding Bhmt was deleted (Bhmt Ϫ/Ϫ ). BHMT activity is found at high levels in the liver and kidney, and low levels in the brain, lenses, and other human tissues. In rodents, high levels of BHMT activity are only found in the liver (6). Betaine, the methyl donor for BHMT, comes from either dietary sources or from oxidation of choline (an irreversible reaction) by choline dehydrogenase (CHDH). Alternatively, choline can be used to form the phospholipid phosphatidylcholine (PtdCho) or the neurotransmitter acetylcholine (7). The product of BHMT, methionine, is the precursor for S-adenosylmethionine (AdoMet), the major methyl donor for most biological methylations, including DNA and histone methylation, the conversion of glycine to methylglycine (catalyzed by glycine methyltransferase (GNMT)), and the methylation of phosphatidylethanolamine (PtdEtn) to form PtdCho (catalyzed by phosphatidylethanolamine N-methyltransferase (PEMT)).The other substrate for BHMT is Hcy, a thiol-containing amino acid, which, when elevated in plasma, is associated with cardiovascular diseases, pregnancy complications, renal insufficiency, and cognitive impairment (8). Hcy is converted to methionine by BHMT or by methionine synthase, the latter of which uses methyltetrahydrofolate (methyl-THF) as the methyl

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Section: Generation Of Bhmtmentioning

confidence: 99%

Deletion of Betaine-Homocysteine S-Methyltransferase in Mice Perturbs Choline and 1-Carbon Metabolism, Resulting in Fatty Liver and Hepatocellular Carcinomas

Teng

Mehedint

Garrow

et al. 2011

Journal of Biological Chemistry

189

175

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“…Determination of SAM and SAH-Tissue concentrations of SAM and SAH were measured by HPLC using a modification of previously described methods (18,49). Briefly, 50 mg of tissue was homogenized in 185 l of 40% trichloroacetic acid and 250 l of cold 0.1 M sodium acetate, pH 6.0.…”

Section: Dietary Intervention During Embryonic Period E11-e17-mentioning

confidence: 99%

Gestational Choline Deficiency Causes Global and Igf2 Gene DNA Hypermethylation by Up-regulation of Dnmt1 Expression

Kovacheva

Mellott

Davison

et al. 2007

Journal of Biological Chemistry

212

191

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During gestation there is a high demand for the essential nutrient choline. Adult rats supplemented with choline during embryonic days (E) 11-17 have improved memory performance and do not exhibit age-related memory decline, whereas prenatally choline-deficient animals have memory deficits. Choline, via betaine, provides methyl groups for the production of S-adenosylmethionine, a substrate of DNA methyltransferases (DNMTs). We describe an apparently adaptive epigenomic response to varied gestational choline supply in rat fetal liver and brain. S-Adenosylmethionine levels increased in both organs of E17 fetuses whose mothers consumed a choline-supplemented diet. Surprisingly, global DNA methylation increased in choline-deficient animals, and this was accompanied by overexpression of Dnmt1 mRNA. Previous studies showed that the prenatal choline supply affects the expression of multiple genes, including insulin-like growth factor 2 (Igf2), whose expression is regulated in a DNA methylation-dependent manner. The differentially methylated region 2 of Igf2 was hypermethylated in the liver of E17 choline-deficient fetuses, and this as well as Igf2 mRNA levels correlated with the expression of Dnmt1 and with hypomethylation of a regulatory CpG within the Dnmt1 locus. Moreover, mRNA expression of brain and liver Dnmt3a and methyl CpG-binding domain 2 (Mbd2) protein as well as cerebral Dnmt3l was inversely correlated to the intake of choline. Thus, choline deficiency modulates fetal DNA methylation machinery in a complex fashion that includes hypomethylation of the regulatory CpGs within the Dnmt1 gene, leading to its overexpression and the resultant increased global and gene-specific (e.g. Igf2) DNA methylation. These epigenomic responses to gestational choline supply may initiate the long term developmental changes observed in rats exposed to varied choline intake in utero.An adequate supply of essential nutrients involved in the metabolism of methyl groups, including folic acid, vitamin B 12 , and choline, is central for normal development of the fetus. This is perhaps best exemplified by the discovery that the dietary supply of folic acid, a vitamin that acts as a coenzyme in one-carbon transfer pathways, during the periconceptual period is critical in prevention of neural tube defects (1). Studies in animal models (2-5) as well as recent epidemiological investigations in humans (6) indicate that choline intake during gestation is particularly important for the normal development and function of the central nervous system. In a frequently used experimental model that employs offspring of pregnant rats or mice consuming diets of varying choline content during the 7-day period of the second half of gestation (embryonic days E11-17), prenatal choline deficiency causes deficits in certain memory tasks (7), whereas prenatal choline supplementation leads to enhanced memory and attention and prevents agerelated memory decline (7-13). These behavioral changes are accompanied by electrophysiological, neuroanatomical, and neuro...

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“…The use of an ionpairing reagent for detection of SAH has been previously demonstrated (13)(14)(15). The use of ion-pairing RP-HPLC (IP-RP-HPLC) specifically in combination with the ISOQUANT kit reagents was investigated.…”

Section: Ion-pairing Rp-hplc Protocolmentioning

confidence: 99%

Development of Improved High-Performance Liquid Chromatography Conditions for Nonisotopic Detection of Isoaspartic Acid to Determine the Extent of Protein Deamidation

Carlson

Riggin

2000

Analytical Biochemistry

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A new high performance liquid chromatographic method for the simultaneous measurement of S‐adenosylmethionine and S‐adenosylhomocysteine concentrations in pig tissues after inactivation of methionine synthase by nitrous oxide

Cited by 37 publications

References 16 publications

Deletion of Betaine-Homocysteine S-Methyltransferase in Mice Perturbs Choline and 1-Carbon Metabolism, Resulting in Fatty Liver and Hepatocellular Carcinomas

Deletion of Betaine-Homocysteine S-Methyltransferase in Mice Perturbs Choline and 1-Carbon Metabolism, Resulting in Fatty Liver and Hepatocellular Carcinomas

Gestational Choline Deficiency Causes Global and Igf2 Gene DNA Hypermethylation by Up-regulation of Dnmt1 Expression

Development of Improved High-Performance Liquid Chromatography Conditions for Nonisotopic Detection of Isoaspartic Acid to Determine the Extent of Protein Deamidation

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