1
|
Li J, Li F, Yu N, Liu Z. The betaine-dependent remethylation pathway is a homocysteine metabolism pathway associated with the carnivorous feeding habits of spiders. INSECT SCIENCE 2022; 29:1047-1058. [PMID: 34647692 DOI: 10.1111/1744-7917.12976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 09/08/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
Homocysteine (Hcy) is a sulfur-containing amino acid derived from the essential amino acid methionine (Met). Circulating levels of Hcy in animals can be increased by feeding on Met-enriched diets, which is generally considered harmful. Spiders are one of the largest groups of obligate carnivores and feed on animals high in protein and Met. We analyzed the Hcy metabolism pathways in 18 species of 3 taxa (Mammalia, Insecta, and Arachnida) and found that the betaine-dependent remethylation pathway (BRP) was present in all carnivorous arachnid species and mammals but absent in insects and red spider mites. We then studied the Hcy metabolism pathway in Pardosa pseudoannulata. In P. pseudoannulata, Hcy is metabolized through the transsulfuration pathway, BRP, and S-methylmethionine-dependent remethylation pathway. Because of a prior duplication event of the betaine homocysteine S-methyltransferase (BHMT) gene in the BRP, BHMTa and BHMTb are present in tandem in the genome of P. pseudoannulata. The high expression levels of BHMTa and its high abundance in detoxification tissues indicate that it plays an important role in the BRP; the ability of BHMTa and BHMTb to remethylate Hcy using betaine as substrate was similar. Compared with other Hcy metabolic enzyme genes, BHMT responded quickly to the application of Hcy or betaine. In sum, the BRP is important in Hcy metabolism in P. pseudoannulata and in other spider species.
Collapse
Affiliation(s)
- Jingjing Li
- Key laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Fangfang Li
- Key laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Na Yu
- Key laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Zewen Liu
- Key laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| |
Collapse
|
2
|
Differentiating Staphylococcus infection-associated glomerulonephritis and primary IgA nephropathy: a mass spectrometry-based exploratory study. Sci Rep 2020; 10:17179. [PMID: 33057112 PMCID: PMC7560901 DOI: 10.1038/s41598-020-73847-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 09/18/2020] [Indexed: 01/18/2023] Open
Abstract
Staphylococcus infection-associated glomerulonephritis (SAGN) and primary IgA nephropathy (IgAN) are separate disease entities requiring different treatment approaches. However, overlapping histologic features may cause a diagnostic dilemma. An exploratory proteomic study to identify potential distinguishing biomarkers was performed on formalin fixed paraffin embedded kidney biopsy tissue, using mass spectrometry (HPLC–MS/MS) (n = 27) and immunohistochemistry (IHC) (n = 64), on four main diagnostic groups—SAGN, primary IgAN, acute tubular necrosis (ATN) and normal kidney (baseline transplant biopsies). Spectral counts modeled as a negative binomial distribution were used for statistical comparisons and in silico pathway analysis. Analysis of variance techniques were used to compare groups and the ROC curve to evaluate classification algorithms. The glomerular proteomes of SAGN and IgAN showed remarkable similarities, except for significantly higher levels of monocyte/macrophage proteins in SAGN—mainly lysozyme and S100A9. This finding was confirmed by IHC. In contrast, the tubulointerstitial proteomes were markedly different in IgAN and SAGN, with a lower abundance of metabolic pathway proteins and a higher abundance of extracellular matrix proteins in SAGN. The stress protein transglutaminase-2 (TGM2) was also significantly higher in SAGN. IHC of differentially-expressed glomerular and tubulointerstitial proteins can be used to help discriminate between SAGN and IgAN in ambiguous cases.
Collapse
|
3
|
Wang X, Kadarmideen HN. Characterization of Global DNA Methylation in Different Gene Regions Reveals Candidate Biomarkers in Pigs with High and Low Levels of Boar Taint. Vet Sci 2020; 7:E77. [PMID: 32545802 PMCID: PMC7356388 DOI: 10.3390/vetsci7020077] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 06/09/2020] [Indexed: 12/11/2022] Open
Abstract
DNA methylation of different gene components, including different exons and introns, or different lengths of exons and introns is associated with differences in gene expression. To investigate the methylation of porcine gene components associated with the boar taint (BT) trait, this study used reduced representation bisulfite sequencing (RRBS) data from nine porcine testis samples in three BT groups (low, medium and high BT). The results showed that the methylation levels of the first exons and first introns were lower than those of the other exons and introns. The first exons/introns of CpG island regions had even lower levels of methylation. A total of 123 differentially methylated promoters (DMPs), 194 differentially methylated exons (DMEs) and 402 differentially methylated introns (DMIs) were identified, of which 80 DMPs (DMP-CpGis), 112 DMEs (DME-CpGis) and 166 DMIs (DMI-CpGis) were discovered in CpG islands. Importantly, GPX1 contained one each of DMP, DME, DMI, DMP-CpGi, DME-CpGi and DMI-CpGi. Gene-GO term relationships and pathways analysis showed DMP-CpGi-related genes are mainly involved in methylation-related biological functions. In addition, gene-gene interaction networks consisted of nodes that were hypo-methylated GPX1, hypo-methylated APP, hypo-methylated ATOX1, hyper-methylated ADRB2, hyper-methylated RPS6KA1 and hyper-methylated PNMT. They could be used as candidate biomarkers for reducing boar taint in pigs, after further validation in large cohorts.
Collapse
Affiliation(s)
| | - Haja N. Kadarmideen
- Quantitative Genomics, Bioinformatics and Computational Biology Group, Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kongens Lyngby, Denmark;
| |
Collapse
|
4
|
Hepatic metabolic effects of Curcuma longa extract supplement in high-fructose and saturated fat fed rats. Sci Rep 2017; 7:5880. [PMID: 28724959 PMCID: PMC5517472 DOI: 10.1038/s41598-017-06220-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 06/08/2017] [Indexed: 12/11/2022] Open
Abstract
The metabolic effects of an oral supplementation with a Curcuma longa extract, at a dose nutritionally relevant with common human use, on hepatic metabolism in rats fed a high fructose and saturated fatty acid (HFS) diet was evaluated. High-resolution magic-angle spinning NMR and GC/MS in combination with multivariate analysis have been employed to characterize the NMR metabolite profiles and fatty acid composition of liver tissue respectively. The results showed a clear discrimination between HFS groups and controls involving metabolites such as glucose, glycogen, amino acids, acetate, choline, lysophosphatidylcholine, phosphatidylethanolamine, and β-hydroxybutyrate as well as an increase of MUFAs and a decrease of n-6 and n-3 PUFAs. Although the administration of CL did not counteract deleterious effects of the HFS diet, some metabolites, namely some n-6 PUFA and n-3 PUFA, and betaine were found to increase significantly in liver samples from rats having received extract of curcuma compared to those fed the HFS diet alone. This result suggests that curcuminoids may affect the transmethylation pathway and/or osmotic regulation. CL extract supplementation in rats appears to increase some of the natural defences preventing the development of fatty liver by acting on the choline metabolism to increase fat export from the liver.
Collapse
|
5
|
Muckova P, Wendler S, Rubel D, Büchler R, Alert M, Gross O, Rhode H. Preclinical Alterations in the Serum of COL(IV)A3–/– Mice as Early Biomarkers of Alport Syndrome. J Proteome Res 2015; 14:5202-14. [DOI: 10.1021/acs.jproteome.5b00814] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Petra Muckova
- Institute
of Biochemistry I, University Hospital Jena, Nonnenplan 2-4, 07740 Jena, Germany
- Clinic
of Neurology, University Hospital Jena, Erlanger Allee 101, 07740 Jena, Germany
| | - Sindy Wendler
- Institute
of Biochemistry I, University Hospital Jena, Nonnenplan 2-4, 07740 Jena, Germany
| | - Diana Rubel
- Department
of Nephrology and Rheumatology, University Medicine Göttingen, Robert-Koch Str. 40, 37075 Göttingen, Germany
| | - Rita Büchler
- Institute
of Biochemistry I, University Hospital Jena, Nonnenplan 2-4, 07740 Jena, Germany
| | - Mandy Alert
- Institute
of Biochemistry I, University Hospital Jena, Nonnenplan 2-4, 07740 Jena, Germany
| | - Oliver Gross
- Department
of Nephrology and Rheumatology, University Medicine Göttingen, Robert-Koch Str. 40, 37075 Göttingen, Germany
| | - Heidrun Rhode
- Institute
of Biochemistry I, University Hospital Jena, Nonnenplan 2-4, 07740 Jena, Germany
| |
Collapse
|
6
|
Ganu RS, Ishida Y, Koutmos M, Kolokotronis SO, Roca AL, Garrow TA, Schook LB. Evolutionary Analyses and Natural Selection of Betaine-Homocysteine S-Methyltransferase (BHMT) and BHMT2 Genes. PLoS One 2015. [PMID: 26213999 PMCID: PMC4516251 DOI: 10.1371/journal.pone.0134084] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Betaine-homocysteine S-methyltransferase (BHMT) and BHMT2 convert homocysteine to methionine using betaine and S-methylmethionine, respectively, as methyl donor substrates. Increased levels of homocysteine in blood are associated with cardiovascular disease. Given their role in human health and nutrition, we identified BHMT and BHMT2 genes and proteins from 38 species of deuterostomes including human and non-human primates. We aligned the genes to look for signatures of selection, to infer evolutionary rates and events across lineages, and to identify the evolutionary timing of a gene duplication event that gave rise to two genes, BHMT and BHMT2. We found that BHMT was present in the genomes of the sea urchin, amphibians, reptiles, birds and mammals; BHMT2 was present only across mammals. BHMT and BHMT2 were present in tandem in the genomes of all monotreme, marsupial and placental species examined. Evolutionary rates were accelerated for BHMT2 relative to BHMT. Selective pressure varied across lineages, with the highest dN/dS ratios for BHMT and BHMT2 occurring immediately following the gene duplication event, as determined using GA Branch analysis. Nine codons were found to display signatures suggestive of positive selection; these contribute to the enzymatic or oligomerization domains, suggesting involvement in enzyme function. Gene duplication likely occurred after the divergence of mammals from other vertebrates but prior to the divergence of extant mammalian subclasses, followed by two deletions in BHMT2 that affect oligomerization and methyl donor specificity. The faster evolutionary rate of BHMT2 overall suggests that selective constraints were reduced relative to BHMT. The dN/dS ratios in both BHMT and BHMT2 was highest following the gene duplication, suggesting that purifying selection played a lesser role as the two paralogs diverged in function.
Collapse
Affiliation(s)
- Radhika S. Ganu
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Yasuko Ishida
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Markos Koutmos
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States of America
| | | | - Alfred L. Roca
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Timothy A. Garrow
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Lawrence B. Schook
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
- * E-mail:
| |
Collapse
|
7
|
Ong JLY, Woo JM, Hiong KC, Ching B, Wong WP, Chew SF, Ip YK. Molecular characterization of betaine-homocysteine methyltransferase 1 from the liver, and effects of aestivation on its expressions and homocysteine concentrations in the liver, kidney and muscle, of the African lungfish, Protopterus annectens. Comp Biochem Physiol B Biochem Mol Biol 2015; 183:30-41. [PMID: 25575738 DOI: 10.1016/j.cbpb.2014.12.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 12/19/2014] [Accepted: 12/23/2014] [Indexed: 01/12/2023]
Abstract
Homocysteine accumulation has numerous deleterious effects, and betaine-homocysteine S-methyltransferase (BHMT) catalyses the synthesis of methionine from homocysteine and betaine. This study aimed to determine homocysteine concentrations, and mRNA expression levels and protein abundances of bhmt1/Bhmt1 in the liver, kidney and muscle of the African lungfish, Protopterus annectens, during the induction (6 days), maintenance (6 months) or arousal (3 days after arousal) phase of aestivation. The homocysteine concentration decreased significantly in the liver of P. annectens after 6 days or 6 months of aestivation, but it returned to the control level upon arousal. By contrast, homocysteine concentrations in the kidney and muscle remained unchanged during the three phases of aestivation. The complete coding cDNA sequence of bhmt1 from P. annectens consisted of 1236 bp, coding for 412 amino acids. The Bhmt1 from P. annectens had a close phylogenetic relationship with those from tetrapods and Callorhinchus milii. The expression of bhmt1 was detected in multiple organs/tissues of P. annectens, and this is the first report on the expression of bhmt1/Bhmt1 in animal skeletal muscle. The mRNA and protein expression levels of bhmt1/Bhmt1 were up-regulated in the liver of P. annectens during the induction and maintenance phases of aestivation, possibly to regulate the hepatic homocysteine concentration. The significant increase in hepatic Bhmt1 protein abundance during the arousal phase could be a response to increased cellular methylation for the purpose of tissue reconstruction. Unlike the liver, Bhmt1 expression in the kidney and muscle of P. annectens was regulated translationally, and its up-regulation could be crucial to prevent homocysteine accumulation.
Collapse
Affiliation(s)
- Jasmine L Y Ong
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Jia M Woo
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Kum C Hiong
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Biyun Ching
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Wai P Wong
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Shit F Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore
| | - Yuen K Ip
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore; The Tropical Marine Science Institute, National University of Singapore, Kent Ridge, Singapore 119227, Republic of Singapore.
| |
Collapse
|
8
|
Ganu R, Garrow T, Koutmos M, Rund L, Schook LB. Splicing variants of the porcine betaine-homocysteine S-methyltransferase gene: implications for mammalian metabolism. Gene 2013; 529:228-37. [PMID: 23948084 PMCID: PMC3894628 DOI: 10.1016/j.gene.2013.07.103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Revised: 07/23/2013] [Accepted: 07/30/2013] [Indexed: 12/18/2022]
Abstract
Betaine-homocysteine S-methyltransferase (BHMT) activity is only detected in the liver of rodents, but in both the liver and kidney cortex of humans and pigs; therefore, the pig was chosen as a model to define the spatial and temporal expression of BHMT during development. During fetal development, a total of ten splice variants of bhmt were expressed at varying levels across a wide range of porcine tissues. Two variants contained an identical ORF that encoded a C-terminal truncated form of BHMT (tBHMT). The bhmt transcripts were expressed at significant levels in the liver and kidney from day 45 of gestation (G45) onward. The transcripts encoding tBHMT represented 5-13% of the total bhmt transcripts in G30 fetus, G45 liver, and adult liver and kidney cortex. The dominant structural feature of wild type BHMT is an (βα)8 barrel, however, a modeled structure of tBHMT suggests that this protein would assume a horseshoe fold and lack methyltransferase activity. Low BHMT activity was detected in the G30 fetus, and slightly increased levels of activity were observed in the liver from G45 and G90 fetuses. The bhmt promoter contained three key CpG sites, and methylation of these sites was significantly higher in adult lung compared to adult liver. The data reported herein suggest that genomic DNA methylation and variation of the 5' and 3' UTRs of bhmt transcripts are key regulators for the level of BHMT transcription and translation.
Collapse
Affiliation(s)
- Radhika Ganu
- Division of Nutritional Sciences, University of Illinois, Urbana, IL 61801
| | - Timothy Garrow
- Department of Food Science and Human Nutrition, University of Illinois, Urbana, IL 61801
| | - Markos Koutmos
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814
| | - Laurie Rund
- Department of Animal Sciences, University of Illinois, Urbana, IL 61801
| | - Lawrence B. Schook
- Division of Nutritional Sciences, University of Illinois, Urbana, IL 61801
- Department of Animal Sciences, University of Illinois, Urbana, IL 61801
| |
Collapse
|
9
|
Moazzami AA, Bondia-Pons I, Hanhineva K, Juntunen K, Antl N, Poutanen K, Mykkänen H. Metabolomics reveals the metabolic shifts following an intervention with rye bread in postmenopausal women--a randomized control trial. Nutr J 2012; 11:88. [PMID: 23088297 PMCID: PMC3493305 DOI: 10.1186/1475-2891-11-88] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Accepted: 10/11/2012] [Indexed: 12/21/2022] Open
Abstract
Background Epidemiological studies have consistently shown that whole grain (WG) cereals can protect against the development of chronic diseases, but the underlying mechanism is not fully understood. Among WG products, WG rye is considered even more potent because of its unique discrepancy in postprandial insulin and glucose responses known as the rye factor. In this study, an NMR-based metabolomics approach was applied to study the metabolic effects of WG rye as a tool to determine the beneficial effects of WG rye on human health. Methods Thirty-three postmenopausal Finnish women with elevated serum total cholesterol (5.0-8.5 mmol/L) and BMI of 20–33 kg/m2 consumed a minimum of 20% of their daily energy intake as high fiber WG rye bread (RB) or refined wheat bread (WB) in a randomized, controlled, crossover design with two 8-wk intervention periods separated by an 8-wk washout period. At the end of each intervention period, fasting serum was collected for NMR-based metabolomics and the analysis of cholesterol fractions. Multilevel partial least squares discriminant analysis was used for paired comparisons of multivariate data. Results The metabolomics analysis of serum showed lower leucine and isoleucine and higher betaine and N,N-dimethylglycine levels after RB than WB intake. To further investigate the metabolic effects of RB, the serum cholesterol fractions were measured. Total- and LDL-cholesterol levels were higher after RB intake than after WB (p<0.05). Conclusions This study revealed favorable shifts in branched amino acid and single carbon metabolism and an unfavorable shift in serum cholesterol levels after RB intake in postmenopausal women, which should be considered for evaluating health beneficial effects of rye products.
Collapse
Affiliation(s)
- Ali A Moazzami
- Department of Chemistry, Swedish University of Agricultural Sciences, P.O. Box 7015, Uppsala, SE 75007, Sweden.
| | | | | | | | | | | | | |
Collapse
|
10
|
Variability of plasma and urine betaine in diabetes mellitus and its relationship to methionine load test responses: an observational study. Cardiovasc Diabetol 2012; 11:34. [PMID: 22510294 PMCID: PMC3395555 DOI: 10.1186/1475-2840-11-34] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 04/17/2012] [Indexed: 11/23/2022] Open
Abstract
Background Since betaine is an osmolyte and methyl donor, and abnormal betaine loss is common in diabetes mellitus (>20% patients), we investigated the relationship between betaine and the post-methionine load rise in homocysteine, in diabetes and control subjects. The post-methionine load test is reported to be both an independent vascular risk factor and a measure of betaine sufficiency. Methods Patients with type 2 diabetes (n = 34) and control subjects (n = 17) were recruited. We measured baseline fasting plasma and 4-hour post-methionine load (L-methionine, 0.1 mg/kg body weight) concentrations of homocysteine, betaine, and the betaine metabolite N,N-dimethylglycine. Baseline urine excretions of betaine, dimethylglycine and glucose were measured on morning urine samples as the ratio to urine creatinine. Statistical determinants of the post-methionine load increase in homocysteine were identified in multiple linear regression models. Results Plasma betaine concentrations and urinary betaine excretions were significantly (p < 0.001) more variable in the subjects with diabetes compared with the controls. Dimethylglycine excretion (p = 0.00014) and plasma dimethylglycine concentrations (p = 0.039) were also more variable. In diabetes, plasma betaine was a significant negative determinant (p < 0.001) of the post-methionine load increase in homocysteine. However, it was not conclusive that this was different from the relationship in the controls. In the patients with diabetes, a strong relationship was found between urinary betaine excretion and urinary glucose excretion (but not with plasma glucose). Conclusions Both high and low plasma betaine concentrations, and high and low urinary betaine excretions, are more prevalent in diabetes. The availability of betaine affects the response in the methionine load test. The benefits of increasing betaine intake should be investigated.
Collapse
|
11
|
Fridman O, Morales AV, Bortoni LE, Turk-Noceto PC, Prieto EA. Corticoadrenal activity in rat regulates betaine-homocysteine S-methyltransferase expression with opposite effects in liver and kidney. J Biosci 2012; 37:115-23. [PMID: 22357209 DOI: 10.1007/s12038-011-9171-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Betaine-homocysteine S-methyltransferase (BHMT) is an enzyme that converts homocysteine (Hcy) to methionine using betaine as a methyl donor. Betaine also acts as osmolyte in kidney medulla, protecting cells from high extracellular osmolarity. Hepatic BHMT expression is regulated by salt intake. Hormones, particularly corticosteroids, also regulate BHMT expression in rat liver. We investigated to know whether the corticoadrenal activity plays a role in kidney BHMT expression. BHMT activity in rat kidneys is several orders of magnitude lower than in rat livers and only restricted to the renal cortex. This study confirms that corticosteroids stimulate BHMT activity in the liver and, for the first time in an animal model, also up-regulate the BHMT gene expression. Besides, unlike the liver, corticosteroids in rat kidney down-regulate BHMT expression and activity. Given that the classical effect of adrenocortical activity on the kidney is associated with sodium and water re-absorption by the distal tubule leading to volume expansion, by promoting lesser use of betaine as a methyl donor, corticosteroids would preserve betaine for its other role as osmoprotectant against changes in the extracellular osmotic conditions. We conclude that corticosteroids are, at least in part, responsible for the inhibition of BHMT expression and activity in rat kidneys.
Collapse
Affiliation(s)
- Osvaldo Fridman
- Centro de Altos Estudios en Ciencias Humanas y de la Salud, Universidad Abierta Interamericana (UAI), Buenos Aires, Argentina.
| | | | | | | | | |
Collapse
|
12
|
Zhou Y, Holmseth S, Hua R, Lehre AC, Olofsson AM, Poblete-Naredo I, Kempson SA, Danbolt NC. The betaine-GABA transporter (BGT1, slc6a12) is predominantly expressed in the liver and at lower levels in the kidneys and at the brain surface. Am J Physiol Renal Physiol 2012; 302:F316-28. [DOI: 10.1152/ajprenal.00464.2011] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The Na+- and Cl−-dependent GABA-betaine transporter (BGT1) has received attention mostly as a protector against osmolarity changes in the kidney and as a potential controller of the neurotransmitter GABA in the brain. Nevertheless, the cellular distribution of BGT1, and its physiological importance, is not fully understood. Here we have quantified mRNA levels using TaqMan real-time PCR, produced a number of BGT1 antibodies, and used these to study BGT1 distribution in mice. BGT1 (protein and mRNA) is predominantly expressed in the liver (sinusoidal hepatocyte plasma membranes) and not in the endothelium. BGT1 is also present in the renal medulla, where it localizes to the basolateral membranes of collecting ducts (particularly at the papilla tip) and the thick ascending limbs of Henle. There is some BGT1 in the leptomeninges, but brain parenchyma, brain blood vessels, ependymal cells, the renal cortex, and the intestine are virtually BGT1 deficient in 1- to 3-mo-old mice. Labeling specificity was assured by processing tissue from BGT1-deficient littermates in parallel as negative controls. Addition of 2.5% sodium chloride to the drinking water for 48 h induced a two- to threefold upregulation of BGT1, tonicity-responsive enhancer binding protein, and sodium- myo-inositol cotransporter 1 (slc5a3) in the renal medulla, but not in the brain and barely in the liver. BGT1-deficient and wild-type mice appeared to tolerate the salt treatment equally well, possibly because betaine is one of several osmolytes. In conclusion, this study suggests that BGT1 plays its main role in the liver, thereby complementing other betaine-transporting carrier proteins (e.g., slc6a20) that are predominantly expressed in the small intestine or kidney rather than the liver.
Collapse
Affiliation(s)
- Y. Zhou
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - S. Holmseth
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - R. Hua
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - A. C. Lehre
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - A. M. Olofsson
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - I. Poblete-Naredo
- Departamento de Genética y Biología Molecular, Centro de Investigación y de studios Avanzados del Instituto Politécnico Nacional, México City, Mexico; and
| | - S. A. Kempson
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - N. C. Danbolt
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| |
Collapse
|
13
|
Moazzami AA, Zhang JX, Kamal-Eldin A, Aman P, Hallmans G, Johansson JE, Andersson SO. Nuclear magnetic resonance-based metabolomics enable detection of the effects of a whole grain rye and rye bran diet on the metabolic profile of plasma in prostate cancer patients. J Nutr 2011; 141:2126-32. [PMID: 22013201 DOI: 10.3945/jn.111.148239] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Prostate cancer (PC) is the most common cancer in the Western world and the second most important cancer causing male deaths, after lung cancer, in the United States and Britain. Lifestyle and dietary changes are recommended for men diagnosed with early-stage PC. It has been shown that a diet rich in whole grain (WG) rye reduces the progression of early-stage PC, but the underlying mechanism is not clear. This study sought to identify changes in the metabolic signature of plasma in patients with early-stage PC following intervention with a diet rich in WG rye and rye bran product (RP) compared with refined white wheat product (WP) as a tool for mechanistic investigation of the beneficial health effects of RP on PC progression. Seventeen PC patients received 485 g RP or WP in a randomized, controlled, crossover design during a period of 6 wk with a 2-wk washout period. At the end of each intervention period, plasma was collected after fasting and used for (1)H NMR-based metabolomics. Multilevel partial least squares discriminant analysis was used for paired comparisons of multivariate data. A metabolomics analysis of plasma showed an increase in 5 metabolites, including 3-hydroxybutyric acid, acetone, betaine, N,N-dimethylglycine, and dimethyl sulfone, after RP. To understand these metabolic changes, fasting plasma homocysteine, leptin, adiponectin, and glucagon were measured separately. The plasma homocysteine concentration was lower (P = 0.017) and that of leptin tended to be lower (P = 0.07) after RP intake compared to WP intake. The increase in plasma 3-hydroxybutyric acid and acetone after RP suggests a shift in energy metabolism from anabolic to catabolic status, which could explain some of the beneficial health effects of WG rye, i.e., reduction in prostate-specific antigen and reduced 24-h insulin secretion. In addition, the increase in betaine and N,N-dimethylglycine and the decrease in homocysteine show a favorable shift in homocysteine metabolism after RP intake.
Collapse
Affiliation(s)
- Ali A Moazzami
- Department of Food Science, Swedish University of Agricultural Sciences, Uppsala, Sweden.
| | | | | | | | | | | | | |
Collapse
|
14
|
Somashekar BS, Amin AG, Rithner CD, Troudt J, Basaraba R, Izzo A, Crick DC, Chatterjee D. Metabolic Profiling of Lung Granuloma in Mycobacterium tuberculosis Infected Guinea Pigs: Ex vivo 1H Magic Angle Spinning NMR Studies. J Proteome Res 2011; 10:4186-95. [DOI: 10.1021/pr2003352] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- B. S. Somashekar
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1682, Fort Collins, Colorado 80523-1682, United States
| | - Anita G. Amin
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1682, Fort Collins, Colorado 80523-1682, United States
| | - Christopher D. Rithner
- Central Instrument Facility, Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - JoLynn Troudt
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1682, Fort Collins, Colorado 80523-1682, United States
| | - Randall Basaraba
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1682, Fort Collins, Colorado 80523-1682, United States
| | - Angelo Izzo
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1682, Fort Collins, Colorado 80523-1682, United States
| | - Dean C. Crick
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1682, Fort Collins, Colorado 80523-1682, United States
| | - Delphi Chatterjee
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1682, Fort Collins, Colorado 80523-1682, United States
| |
Collapse
|
15
|
Ueland PM. Choline and betaine in health and disease. J Inherit Metab Dis 2011; 34:3-15. [PMID: 20446114 DOI: 10.1007/s10545-010-9088-4] [Citation(s) in RCA: 365] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 03/08/2010] [Accepted: 03/11/2010] [Indexed: 10/19/2022]
Abstract
Choline is an essential nutrient, but is also formed by de novo synthesis. Choline and its derivatives serve as components of structural lipoproteins, blood and membrane lipids, and as a precursor of the neurotransmitter acetylcholine. Pre-and postnatal choline availability is important for neurodevelopment in rodents. Choline is oxidized to betaine that serves as an osmoregulator and is a substrate in the betaine-homocysteine methyltransferase reaction, which links choline and betaine to the folate-dependent one-carbon metabolism. Choline and betaine are important sources of one-carbon units, in particular, during folate deficiency. Choline or betaine supplementation in humans reduces concentration of total homocysteine (tHcy), and plasma betaine is a strong predictor of plasma tHcy in individuals with low plasma concentration of folate and other B vitamins (B₂, B₆, and B₁₂) in combination TT genotype of the methylenetetrahydrofolate reductase 677 C->T polymorphism. The link to one-carbon metabolism and the recent availability of food composition data have motivated studies on choline and betaine as risk factors of chronic diseases previously studied in relation to folate and homocysteine status. High intake and plasma level of choline in the mother seems to afford reduced risk of neural tube defects. Intake of choline and betaine shows no consistent relation to cancer or cardiovascular risk or risk factors, whereas an unfavorable cardiovascular risk factor profile was associated with high choline and low betaine concentrations in plasma. Thus, choline and betaine showed opposite relations with key components of metabolic syndrome, suggesting a disruption of mitochondrial choline oxidation to betaine as part of the mitochondrial dysfunction in metabolic syndrome.
Collapse
Affiliation(s)
- Per Magne Ueland
- Section for Pharmacology, Institute of Medicine, University of Bergen, Bergen, Norway.
| |
Collapse
|
16
|
Ganu RS, Garrow TA, Sodhi M, Rund LA, Schook LB. Molecular characterization and analysis of the porcine betaine homocysteine methyltransferase and betaine homocysteine methyltransferase-2 genes. Gene 2010; 473:133-8. [PMID: 21156199 DOI: 10.1016/j.gene.2010.11.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 11/25/2010] [Accepted: 11/29/2010] [Indexed: 02/03/2023]
Abstract
Betaine homocysteine methyltransferase (BHMT) and BHMT-2 enzymes methylate homocysteine to form methionine using betaine and S-methylmethionine, respectively. These activities are observed only in the liver of adult rodents, but in adult humans and pigs these activities are detected in both the liver and kidney, indicating the pig is a more appropriate model for studying the biochemical and physiological roles of these enzymes in human biology. Porcine BHMT and BHMT-2 cDNAs were cloned and sequenced, and their 5' and 3' UTR were amplified using RLM-RACE. The BHMT transcript had significantly longer 5' and 3' UTRs than BHMT-2. The pig BHMT and BHMT-2 genes span approximately 26 and 16kb, respectively, and both genes have 8 exons. The deduced amino acid sequences of BHMT and BHMT-2 contain 407 and 363 amino acids, respectively, and shared 78% amino acid identity. No promoter element (TATA or CAAT box) was observed for either BHMT or BHMT-2, although a CpG island surrounding the promoter and transcriptional start site was observed in both genes implying that methylation could regulate their expression. Using qPCR, it was determined that BHMT and BHMT-2 transcripts are very abundant in liver and kidney cortex, whereas the expression is significantly less in other tissues. These findings confirm that the expression pattern of BHMT and BHMT-2 genes in pigs is similar to humans, supporting the use of the pig as an animal model to study the genetics and regulation of BHMT and BHMT-2 expression.
Collapse
Affiliation(s)
- Radhika S Ganu
- Division of Nutritional Sciences, University of Illinois at Urbana Champaign, 1201 W. Gregory Dr., Urbana, IL 61801, USA
| | | | | | | | | |
Collapse
|
17
|
New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre? Nutr Res Rev 2010; 23:65-134. [PMID: 20565994 DOI: 10.1017/s0954422410000041] [Citation(s) in RCA: 587] [Impact Index Per Article: 41.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epidemiological studies have clearly shown that whole-grain cereals can protect against obesity, diabetes, CVD and cancers. The specific effects of food structure (increased satiety, reduced transit time and glycaemic response), fibre (improved faecal bulking and satiety, viscosity and SCFA production, and/or reduced glycaemic response) and Mg (better glycaemic homeostasis through increased insulin secretion), together with the antioxidant and anti-carcinogenic properties of numerous bioactive compounds, especially those in the bran and germ (minerals, trace elements, vitamins, carotenoids, polyphenols and alkylresorcinols), are today well-recognised mechanisms in this protection. Recent findings, the exhaustive listing of bioactive compounds found in whole-grain wheat, their content in whole-grain, bran and germ fractions and their estimated bioavailability, have led to new hypotheses. The involvement of polyphenols in cell signalling and gene regulation, and of sulfur compounds, lignin and phytic acid should be considered in antioxidant protection. Whole-grain wheat is also a rich source of methyl donors and lipotropes (methionine, betaine, choline, inositol and folates) that may be involved in cardiovascular and/or hepatic protection, lipid metabolism and DNA methylation. Potential protective effects of bound phenolic acids within the colon, of the B-complex vitamins on the nervous system and mental health, of oligosaccharides as prebiotics, of compounds associated with skeleton health, and of other compounds such as alpha-linolenic acid, policosanol, melatonin, phytosterols and para-aminobenzoic acid also deserve to be studied in more depth. Finally, benefits of nutrigenomics to study complex physiological effects of the 'whole-grain package', and the most promising ways for improving the nutritional quality of cereal products are discussed.
Collapse
|
18
|
Jacobs RL, Zhao Y, Koonen DPY, Sletten T, Su B, Lingrell S, Cao G, Peake DA, Kuo MS, Proctor SD, Kennedy BP, Dyck JRB, Vance DE. Impaired de novo choline synthesis explains why phosphatidylethanolamine N-methyltransferase-deficient mice are protected from diet-induced obesity. J Biol Chem 2010; 285:22403-13. [PMID: 20452975 DOI: 10.1074/jbc.m110.108514] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Phosphatidylcholine (PC) is synthesized from choline via the CDP-choline pathway. Liver cells can also synthesize PC via the sequential methylation of phosphatidylethanolamine, catalyzed by phosphatidylethanolamine N-methyltransferase (PEMT). The current study investigates whether or not hepatic PC biosynthesis is linked to diet-induced obesity. Pemt(+/+) mice fed a high fat diet for 10 weeks increased in body mass by 60% and displayed insulin resistance, whereas Pemt(-/-) mice did not. Compared with Pemt(+/+) mice, Pemt(-/-) mice had increased energy expenditure and maintained normal peripheral insulin sensitivity; however, they developed hepatomegaly and steatosis. In contrast, mice with impaired biosynthesis of PC via the CDP-choline pathway in liver became obese when fed a high fat diet. We, therefore, hypothesized that insufficient choline, rather than decreased hepatic phosphatidylcholine, was responsible for the lack of weight gain in Pemt(-/-) mice despite the presence of 1.3 g of choline/kg high fat diet. Supplementation with an additional 2.7 g of choline (but not betaine)/kg of diet normalized energy metabolism, weight gain, and insulin resistance in high fat diet-fed Pemt(-/-) mice. Furthermore, Pemt(+/+) mice that were fed a choline-deficient diet had increased oxygen consumption, had improved glucose tolerance, and gained less weight. Thus, de novo synthesis of choline via PEMT has a previously unappreciated role in regulating whole body energy metabolism.
Collapse
Affiliation(s)
- René L Jacobs
- Group on the Molecular and Cell Biology of Lipids and Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Bertram HC, Malmendal A, Nielsen NC, Straadt IK, Larsen T, Bach Knudsen KE, Nygaard Laerke H. NMR-based metabonomics reveals that plasma betaine increases upon intake of high-fiber rye buns in hypercholesterolemic pigs. Mol Nutr Food Res 2009; 53:1055-62. [DOI: 10.1002/mnfr.200800344] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
20
|
Konstantinova SV, Tell GS, Vollset SE, Nygård O, Bleie Ø, Ueland PM. Divergent associations of plasma choline and betaine with components of metabolic syndrome in middle age and elderly men and women. J Nutr 2008; 138:914-20. [PMID: 18424601 DOI: 10.1093/jn/138.5.914] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Choline is involved in the synthesis of phospholipids, including blood lipids, and is the immediate precursor of betaine, which serves as a methyl group donor in a reaction converting homocysteine to methionine. Several cardiovascular risk factors are associated with plasma homocysteine, whereas little is known about their relationship to choline and betaine. We examined the relation of plasma choline and betaine to smoking, physical activity, BMI, percent body fat, waist circumference, blood pressure, serum lipids, and glucose in a population-based study of 7074 men and women aged 47-49 and 71-74 y. Overall plasma concentrations (means +/- SD) were 9.9 +/- 2.3 micromol/L for choline and 39.5 +/- 12.5 micromol/L for betaine. Choline and betaine were lower in women than in men and in younger subjects compared with older (P < 0.0001). Multivariate analyses showed that choline was positively associated with serum triglycerides, glucose, BMI, percent body fat, waist circumference (P < 0.0001 for all), and physical activity (P < 0.05) and inversely related to HDL cholesterol (P < 0.05) and smoking (P < 0.0001). Betaine was inversely associated with serum non-HDL cholesterol, triglycerides, BMI, percent body fat, waist circumference, systolic and diastolic blood pressure (P < 0.0001 for all), and smoking (P < 0.05) and positively associated with HDL cholesterol (P < 0.01) and physical activity (P < 0.0001). Thus, an unfavorable cardiovascular risk factor profile was associated with high choline and low betaine concentrations. Choline and betaine were associated in opposite directions with key components of metabolic syndrome, suggesting a disruption of mitochondrial choline dehydrogenase pathway.
Collapse
|
21
|
Lever M, Atkinson W, George PM, Chambers ST. Sex differences in the control of plasma concentrations and urinary excretion of glycine betaine in patients attending a lipid disorders clinic. Clin Biochem 2007; 40:1225-31. [PMID: 17706956 DOI: 10.1016/j.clinbiochem.2007.05.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Revised: 05/22/2007] [Accepted: 05/23/2007] [Indexed: 11/21/2022]
Abstract
OBJECTIVES To find whether the control of betaine metabolism differs between male and female patients and identify the effects of insulin and other hormones. DESIGN AND METHODS Data from non-diabetic lipid clinic patients (82 female symbol and 76 male symbol) were re-analyzed by sex. Data on insulin, thyroid hormones and leptin were included in models to identify factors affecting the circulation and excretion of betaine and its metabolites. RESULTS Different factors influenced plasma concentrations and urinary excretion of betaine, dimethylglycine and homocysteine in males and females. In males, apolipoprotein B (negative), thyroid stimulating hormone (positive) and insulin (negative) predicted circulating betaine, consistent with betaine-homocysteine methyltransferase mediated control. In females, insulin positively predicted plasma dimethylglycine. Urinary betaine excretion positively predicted circulating homocysteine in males (p<0.001), whereas dimethylglycine excretion (also indicating betaine loss) was a stronger positive predictor (p<0.001) in females. Carnitine affected betaine homeostasis. CONCLUSIONS Betaine metabolism is under endocrine control, and studies should use sex stratified groups.
Collapse
Affiliation(s)
- Michael Lever
- Clinical Biochemistry Unit, Canterbury Health Laboratories, Christchurch, New Zealand.
| | | | | | | |
Collapse
|
22
|
Lever M, Atkinson W, George PM, Chambers ST. An abnormal urinary excretion of glycine betaine may persist for years. Clin Biochem 2007; 40:798-801. [PMID: 17490630 DOI: 10.1016/j.clinbiochem.2007.03.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Accepted: 03/14/2007] [Indexed: 01/15/2023]
Abstract
OBJECTIVES Does abnormal betaine excretion persist? DESIGN AND METHODS Patients (10) with abnormal excretion in 1998 were recalled in 2005. Subsequent urine samples were collected on 4 days from persistently abnormal subjects. RESULTS Half the 1998 abnormal patients were abnormal in 2005. Only 1/20 controls was abnormal (p=0.015). All patients with abnormal excretion in 1998 and 2005 had abnormal excretion on successive days while no controls did. CONCLUSIONS High betaine excretion may be chronic and a health risk.
Collapse
Affiliation(s)
- Michael Lever
- Clinical Biochemistry Unit, Canterbury Health Laboratories, Christchurch School of Medicine and Health Sciences, Christchurch, New Zealand.
| | | | | | | |
Collapse
|
23
|
Cohen-Salmon M, Regnault B, Cayet N, Caille D, Demuth K, Hardelin JP, Janel N, Meda P, Petit C. Connexin30 deficiency causes instrastrial fluid-blood barrier disruption within the cochlear stria vascularis. Proc Natl Acad Sci U S A 2007; 104:6229-34. [PMID: 17400755 PMCID: PMC1851033 DOI: 10.1073/pnas.0605108104] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The endocochlear potential (EP) is essential to hearing, because it provides approximately half of the driving force for the mechanoelectrical transduction current in auditory hair cells. The EP is produced by the stria vascularis (SV), a vascularized bilayer epithelium of the cochlea lateral wall. The absence of the gap junction protein connexin30 (Cx30) in Cx30(-/-) mice results in the SV failure to produce an EP, which mainly accounts for the severe congenital hearing impairment of these mice. Here, we show that the SV components of the EP electrogenic machinery and the epithelial barriers limiting the intrastrial fluid space, which are both necessary for the EP production, were preserved in Cx30(-/-) mice. In contrast, the endothelial barrier of the capillaries supplying the SV was disrupted before EP onset. This disruption is expected to result in an intrastrial electric shunt that is sufficient to account for the absence of the EP production. Immunofluorescence analysis of wild-type mice detected Cx30 in the basal and intermediate cells of the SV but not in the endothelial cells of the SV capillaries. Moreover, dye-coupling experiments showed that endothelial cells were not coupled to the SV basal, intermediate, and marginal cells. SV transcriptome analysis revealed a significant down-regulation of betaine homocysteine S-methyltransferase (Bhmt) in the Cx30(-/-) mice, which was restricted to the SV and resulted in a local increase in homocysteine, a known factor of endothelial dysfunction. Disruption of the SV endothelial barrier is a previously undescribed pathogenic process underlying hearing impairment.
Collapse
Affiliation(s)
- Martine Cohen-Salmon
- Unité de Génétique des Déficits Sensoriels, Unité Mixte de Recherche S 587, Institut National de la Santé et de la Recherche Médicale, 75724 Paris Cedex 15, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Lever M, Atkinson W, Sizeland PCB, Chambers ST, George PM. Inter- and intra-individual variations in normal urinary glycine betaine excretion. Clin Biochem 2007; 40:447-53. [PMID: 17335790 DOI: 10.1016/j.clinbiochem.2006.10.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Revised: 08/23/2006] [Accepted: 10/10/2006] [Indexed: 01/15/2023]
Abstract
OBJECTIVES To establish whether normal human subjects excrete glycine betaine at a constant rate. DESIGN AND METHODS Urine was collected from ten normal healthy male subjects for 14 days, during which fluid intake was systematically varied from <800 mL to >3 L per day. Glycine betaine, sorbitol and creatinine excretions were estimated per day and as millimole per mol creatinine. RESULTS The intrasubject SD of urine glycine betaine was 3.5 mmol/mol creatinine, and the intersubject SD 5.8 mmol/mol creatinine. The intrasubject SD of plasma glycine betaine was 10.2 mol/L and the intersubject SD 14.2 mol/L. Water load had little effect on glycine betaine excretion and plasma glycine betaine. After 12 years, excretions and plasma concentrations tended to parallel the initial results. CONCLUSIONS Normal subjects have consistent individual glycine betaine excretions that are not strongly influenced by urine volume. Abnormal excretions, or significant changes in excretion, can be interpreted as indicating a pathological process.
Collapse
Affiliation(s)
- Michael Lever
- Clinical Biochemistry Unit, Canterbury Health Laboratories, Christchurch School of Medicine and Health Sciences, Christchurch, New Zealand.
| | | | | | | | | |
Collapse
|
25
|
Slow S, Garrow TA. Liver choline dehydrogenase and kidney betaine-homocysteine methyltransferase expression are not affected by methionine or choline intake in growing rats. J Nutr 2006; 136:2279-83. [PMID: 16920841 DOI: 10.1093/jn/136.9.2279] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Choline dehydrogenase (CHDH) and betaine-homocysteine methyltransferase (BHMT) are 2 enzymes involved in choline oxidation. BHMT is expressed at high levels in rat liver and its expression is regulated by dietary Met and choline. BHMT is also found in rat kidney, albeit in substantially lower amounts, but it is not known whether kidney BHMT expression is regulated by dietary Met or choline. Similarly, CHDH activity is highest in the liver and kidney, but the regulation of its expression by diet has not been thoroughly investigated. Sprague Dawley rats ( approximately 50 g) were fed, for 9 d in 2 x 3 factorial design (n = 8), an l-amino acid-defined diet varying in l-Met (0.125, 0.3, or 0.8%) and choline (0 or 25 mmol/kg diet). Liver and kidney BHMT and CHDH were assessed using enzymatic, Western blot, and real-time PCR analyses. Liver samples were also fixed for histological analysis. Liver BHMT activity was 1.3-fold higher in rats fed the Met deficient diet containing choline, which was reflected in corresponding increases in mRNA content and immunodetectable protein. Independent of dietary choline, supplemental Met increased hepatic BHMT activity approximately 30%. Kidney BHMT and liver CHDH expression were refractory to these diets. Some degree of fatty liver developed in all rats fed a choline-devoid diet, indicating that supplemental Met cannot completely compensate for the lack of dietary choline in growing rats.
Collapse
Affiliation(s)
- Sandy Slow
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana IL 61801, USA
| | | |
Collapse
|
26
|
Jiráček J, Collinsová M, Rosenberg I, Buděšínský M, Protivínská E, Netušilová H, Garrow TA. S-alkylated homocysteine derivatives: new inhibitors of human betaine-homocysteine S-methyltransferase. J Med Chem 2006; 49:3982-9. [PMID: 16789755 PMCID: PMC2622432 DOI: 10.1021/jm050885v] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A series of S-alkylated derivatives of homocysteine were synthesized and characterized as inhibitors of human recombinant betaine-homocysteine S-methyltransferase (BHMT). Some of these compounds inhibit BHMT with IC50 values in the nanomolar range. BHMT is very sensitive to the structure of substituents on the sulfur atom of homocysteine. The S-carboxybutyl and S-carboxypentyl derivatives make the most potent inhibitors, and an additional sulfur atom in the alkyl chain is well tolerated. The respective (R,S)-5-(3-amino-3-carboxy-propylsulfanyl)-pentanoic, (R,S)-6-(3-amino-3-carboxy-propylsulfanyl)-hexanoic, and (R,S)-2-amino-4-(2-carboxymethylsulfanyl-ethylsulfanyl)-butyric acids are very potent inhibitors and are the strongest ever reported. We determined that (R,S)-5-(3-amino-3-carboxy-propylsulfanyl)-pentanoic acid displays competitive inhibition with respect to betaine binding with a Kappi of 12 nM. Some of these compounds are currently being tested in mice to study the influence of BHMT on the metabolism of sulfur amino acids in vivo.
Collapse
Affiliation(s)
- Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
- Corresponding authors. Tel +420220183441, fax +420220183571, e-mails ,
| | - Michaela Collinsová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Ivan Rosenberg
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
- Corresponding authors. Tel +420220183441, fax +420220183571, e-mails ,
| | - Miloš Buděšínský
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Eva Protivínská
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Hana Netušilová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Timothy A. Garrow
- Department of Food Science and Human Nutrition, University of Illinois, Urbana, Illinois 61801, USA
| |
Collapse
|
27
|
Collinsova M, Strakova J, Jiracek J, Garrow TA. Inhibition of betaine-homocysteine S-methyltransferase causes hyperhomocysteinemia in mice. J Nutr 2006; 136:1493-7. [PMID: 16702310 DOI: 10.1093/jn/136.6.1493] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Inhibitors and methyl donor substrates for betaine-homocysteine S-methyltransferase (BHMT) were used to study the role of this enzyme in the regulation of plasma total homocysteine (tHcy). Mice were administered an i.p. injection of S-(delta-carboxybutyl)-dl-homocysteine (CBHcy; 1 mg), a specific and potent inhibitor of BHMT, and tHcy and hepatic BHMT protein and activity levels were monitored over a 24-h period. Compared with saline-injected control mice, at 2 h postinjection, the CBHcy-treated mice had 87% lower BHMT activity and a 2.7-fold increase (11.1 vs. 3.0 micromol/L) in tHcy, effects that lasted nearly 8 h but returned to normal by 24 h. The level of BHMT protein remained constant over the 24-h period. After 6 CBHcy (1 mg) injections (one every 12 h), the mice had 7-fold higher tHcy, a 65% reduction in the liver S-adenosylmethionine:S-adenosylhomocysteine ratio, and a marked upregulation of BHMT protein expression. At 2 h after injection of the sulfoxide derivative of CBHcy (10 mg) into mice, there was a modest reduction in BHMT activity and a 90% increase in tHcy. When given an injection of Met (3 mg) or Met plus CBHcy (1 mg), post-Met load tHcy levels were 2.2-fold higher (128 vs. 40 micromol/L) at 2 h postinjection in the mice given CBHcy. Like betaine, dimethylsulfoniopropionate was an effective tHcy-lowering agent when given with a Met load. These studies are the first to show that transient inhibition of BHMT in vivo causes transient hyperhomocysteinemia, and that dimethylsulfoniopropionate can reduce a post-Met load rise in tHcy.
Collapse
Affiliation(s)
- Michaela Collinsova
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | | | | |
Collapse
|
28
|
Garrido F, Gasset M, Sanz-Aparicio J, Alfonso C, Pajares M. Rat liver betaine-homocysteine S-methyltransferase equilibrium unfolding: insights into intermediate structure through tryptophan substitutions. Biochem J 2006; 391:589-99. [PMID: 15943585 PMCID: PMC1276960 DOI: 10.1042/bj20050505] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Equilibrium folding of rat liver BHMT (betaine-homocysteine methyltransferase), a TIM (triosephosphate isomerase)-barrel tetrameric protein, has been studied using urea as denaturant. A combination of activity measurements, tryptophan fluorescence, CD and sedimentation-velocity studies suggested a multiphasic process including two intermediates, a tetramer (I4) and a monomer (J). Analysis of denaturation curves for single- and six-tryptophan mutants indicated that the main changes leading to the tetrameric intermediate are related to alterations in the helix alpha4 of the barrel, as well as in the dimerization arm. Further dissociation to intermediate J included changes in the loop connecting the C-terminal alpha-helix of contact between dimers, disruption of helix alpha4, and initial alterations in helix alpha7 of the barrel, as well as in the dimerization arm. Evolution of the monomeric intermediate continued through additional perturbations in helix alpha7 of the barrel and the C-terminal loop. Our data highlight the essential role of the C-terminal helix in dimer-dimer binding through its contribution to the increased stability shown by BHMT as compared with other TIM barrel proteins. The results are discussed in the light of the high sequence conservation shown by betaine-homocysteine methyltransferases and the knowledge available for other TIM-barrel proteins.
Collapse
Affiliation(s)
- Francisco Garrido
- *Instituto de Investigaciones Biomédicas ‘Alberto Sols’ (CSIC-UAM), Arturo Duperier 4, 28029 Madrid, Spain
| | - María Gasset
- †Instituto de Química-Física ‘Rocasolano’ (CSIC), Serrano 119, 28006 Madrid, Spain
| | | | - Carlos Alfonso
- ‡Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - María A. Pajares
- *Instituto de Investigaciones Biomédicas ‘Alberto Sols’ (CSIC-UAM), Arturo Duperier 4, 28029 Madrid, Spain
- To whom correspondence should be addressed (email )
| |
Collapse
|