Growth requirement for methionine in human melanoma-derived cell lines with different levels of MMACHC expression and methylation.

Methionine dependence, the inability to grow in culture when methionine in the medium is replaced by its metabolic precursor homocysteine, occurs in many tumor cell lines. In most affected lines, the cause of methionine dependence is not known. An exception is the melanoma-derived cell line MeWo-LC1, in which hypermethylation of the MMACHC gene is associated with decreased MMACHC expression. Decreased expression results in decreased provision of the methylcobalamin cofactor required for activity of methionine synthase and thus decreased conversion of homocysteine to methionine. Analysis of data in the Cancer Cell Line Encyclopedia Archive demonstrated that MMACHC hypermethylation and decreased MMACHC expression occurred more frequently in melanoma cell lines when compared to other tumor cell lines. We further investigated methionine dependence and aspects of MMACHC function in a panel of six melanoma lines, including both melanoma lines with known methionine dependence status (MeWo, which is methionine independent, and A375, which is methionine dependent). We found that the previously unclassified melanoma lines HMCB, Colo829 and SH-4 were methionine dependent, while SK-Mel-28 was methionine independent. However, despite varying levels of MMACHC methylation and expression, none of the tested lines had decreased methylcobalamin and adenosylcobalamin synthesis as seen in MeWo-LC1, and the functions of both cobalamin-dependent enzymes methionine synthase and methylmalonyl-CoA mutase were intact. Thus, while melanoma lines were characterized by relatively high levels of MMACHC methylation and low expression, the defect in metabolism observed in MeWo-LC1 was unique, and decreased MMACHC expression was not a cause of methionine dependence in the other melanoma lines.

Association of MTR and MTRR genes and oral health-related quality of life in children with dental caries.

This study aimed to assess whether genetic polymorphisms in MTR and MTRR are potential biomarkers of oral health-related quality of life (OHRQoL) in children with caries. A cross-sectional study was designed wherein pairs of parents/caregivers and children (aged two-five years) were selected. Clinical examination was used to detect dental caries, which were classified as low-severity and high-severity caries. The Early Childhood Oral Health Impact Scale (ECOHIS) questionnaire was used to assess OHRQoL. Genomic DNA extracted from the saliva was used to analyze two missense genetic polymorphisms: MTR (rs1805087) and MTRR (rs1801394). Mann-Whitney non-parametric test was used to analyze candidate genes with OHRQoL scale and domain, with a significance level of p≤0.05. MTR (rs1805087) was found associated (p = 0.05) with children's OHRQoL subscale scores in the dominant model (GG + AG). Genetic polymorphisms in MTR may increase the risk of poor OHRQoL in children with caries. Further studies are needed to investigate genetics, molecular factors, and OHRQoL.

Association of MTR gene polymorphisms with the occurrence of non-syndromic congenital heart disease: a case-control study.

To exhaustively explore the association of infant genetic polymorphisms of methionine synthase (MTR) gene with the risk of non-syndromic congenital heart disease (CHD). A hospital-based case-control study involving 620 CHD cases and 620 health controls was conducted from November 2017 to March 2020. Eighteen SNPs were detected and analyzed. Our date suggested that the genetic polymorphisms of MTR gene at rs1805087 (GG vs. AA: aOR = 6.85, 95% CI 2.94-15.96; the dominant model: aOR = 1.77, 95% CI 1.35-2.32; the recessive model: aOR = 6.26, 95% CI 2.69-14.54; the addictive model: aOR = 1.81, 95% CI 1.44-2.29) and rs2275565 (GT vs. GG: aOR = 1.52, 95% CI 1.15-1.20; TT vs. GG: aOR = 4.93, 95% CI 1.93-12.58; the dominant model: aOR = 1.66, 95% CI 1.27-2.17; the recessive model: aOR = 4.41, 95% CI 1.73-11.22; the addictive model: aOR = 1.68, 95% CI 1.32-2.13) were significantly associated with the higher risk of CHD. And three haplotypes of G-A-T (involving rs4659724, rs95516 and rs4077829; OR = 5.48, 95% CI 2.58-11.66), G-C-A-T-T-G (involving rs2275565, rs1266164, rs2229276, rs4659743, rs3820571 and rs1050993; OR = 0.78, 95% CI 0.63-0.97) and T-C-A-T-T-G (involving rs2275565, rs1266164, rs2229276, rs4659743, rs3820571 and rs1050993; OR = 1.60, 95% CI 1.26-2.04) were observed to be significantly associated with risk of CHD. Our study found that genetic polymorphisms of MTR gene at rs1805087 and rs2275565 were significantly associated with higher risk of CHD. Additionally, our study revealed a significant association of three haplotypes with risk of CHD. However, the limitations in this study should be carefully taken into account. In the future, more specific studies in different ethnic populations are required to refine and confirm our findings.Trial registration: Registration number: ChiCTR1800016635; Date of first registration: 14/06/2018.

Association of MTR A2756G and MTRR A66G Polymorphisms With Male Infertility: An Updated Meta-Analysis.

The objective of the present study was to find out the association of folate genes MTR A2756G and MTRR A66G polymorphisms with the risk of male infertility. The databases of Google Scholar, PubMed, and Science Direct were searched to find relevant studies. Data were extracted from the eligible studies and were analyzed for pooled up odds ratio (OR) with 95% confidence interval (CI). Review Manager 5.4 was used for statistical analysis. Nineteen case-control studies were included in this meta-analysis which comprised 3621 cases and 3327 controls. Pooled analysis revealed that there is a significant association between MTR A2756G polymorphism with male infertility except for the dominant model. The ORs and 95% CI for each genetic model were as follows: 1.21 [1.03-1.42] for the allele model (G vs. A), 2.31 [1.38-3.96] for the additive model (GG vs. AA), 1.17 [0.98-1.38] for the dominant model (GG+AG vs. AA) and 2.10 [1.55-2.86] for the recessive model (GG vs. AG+AA). MTRR A66G has no noticeable association with male infertility. The current meta-analysis suggests that MTR A2756G polymorphism might be a potential risk factor for male infertility. In the future, the sample size should be increased to confirm the present results.

Genetic Polymorphisms of Gene Methionine Synthase Reductase (MTRR) and Risk of Urinary Bladder Cancer.

Methionine synthase reductase (MTRR) gene involved in the signaling for production of enzyme called methionine synthase reductase that use for the synthesis of methionine, which further used in DNA replication and repair. Genetic variation in MTRR gene may alter the susceptibility of developing urinary bladder cancer. The present study undertaken to identify the contribution of genetic polymorphisms in the MTRR gene on the selected polymorphic sites including c.66A>G and c.524C>T towards urinary bladder cancer risk. Direct-DNA sequencing method was applied for the observation of genotyping distribution of MTRR c.66A>G and c.524C>T polymorphisms in 232 histopathological confirmed cases of transitional cell carcinoma (TCC) of urinary bladder cancer and 250 age-, sex- and ethnicity-matched cancer free controls. With significant difference (p = 0.05) of genotype analysis further corresponding Odds ratio (OR) and 95% confidence interval (CI) were calculated. Multivariable logistic regression analysis was applied for adjusting significant confounder variables. Haploview software (version 4.2) was used to perform pairwise Linkage Disequilibrium (LD) analysis. Age (p = 0.01), Habit of smoking (p = 0.05), tobacco consumption (p = 0.001) and diet (p = 0.02) were significantly differed between cases and controls. Both the MTRR substitution showed higher risk of developing urinary bladder cancer (p = <0.001), although this effect alters in multivariable logistic regression analysis in a protective association for both the substitution. No LD observed between the c.66A>G and c.524C>T substitutions. In conclusion, MTRR c.66A>G and c.524C>T substitutions showed a joint effect with the other associated risk factors. Further studies with a greater number of subjects of different ethnicity and polymorphisms are recommended for the better understanding urinary bladder cancer etiology and to screen the population who are at higher risk of developing urinary bladder cancer.

Development of vitamin B12 dependency in Saccharomyces cerevisiae.

For decades, the industrial vitamin B12 (cobalamin) production has been based on bacterial producer strains. Due to limited methods for strain optimization and difficult strain handling, the desire for new vitamin B12-producing hosts has risen. As a vitamin B12-independent organism with a big toolbox for genomic engineering and easy-to-handle cultivation conditions, Saccharomyces cerevisiae has high potential for heterologous vitamin B12 production. However, the B12 synthesis pathway is long and complex. To be able to easily engineer and evolve B12-producing recombinant yeast cells, we have developed an S. cerevisiae strain whose growth is dependent on vitamin B12. For this, the B12-independent methionine synthase Met6 of yeast was replaced by a B12-dependent methionine synthase MetH from Escherichia coli. Adaptive laboratory evolution, RT-qPCR, and overexpression experiments show that additional high-level expression of a bacterial flavodoxin/ferredoxin-NADP+ reductase (Fpr-FldA) system is essential for in vivo reactivation of MetH activity and growth. Growth of MetH-containing yeast cells on methionine-free media is only possible with the addition of adenosylcobalamin or methylcobalamin. A heterologous vitamin B12 transport system turned out to be not necessary for the uptake of cobalamins. This strain should be a powerful chassis to engineer B12-producing yeast cells.

The inhibitory effect of vitamin D on myocardial homocysteine levels involves activation of Nrf2-mediated methionine synthase.

BACKGROUND: Homocysteine (Hcy) is a synthetic amino acid containing sulfhydryl group, which is an intermediate product of the deep metabolic pathway of methionine and cysteine. The abnormal increase in fasting plasma total Hcy concentration caused by various factors is called hyperhomocysteine (HHcy). HHcy is closely relevant to the occurrence and progression of diverse cardiovascular and cerebrovascular diseases, such as coronary heart disease, hypertension and diabetes, etc. Vitamin D/vitamin D receptor (VDR) pathway is pointed out that prevent cardiovascular disease by reducing serum homocysteine levels. Our research is designed to explore the potential mechanism of vitamin D in the prevention and treatment of HHcy. METHODS AND RESULTS: The Hcy and 25(OH)D3 levels in mouse myocardial tissue, serum or myocardial cells were detected using ELISA kits. The expression levels of VDR, Nrf2 and methionine synthase (MTR) were observed using Western blotting, immunohistochemistry and real time polymerase chain reaction (PCR). General information of the mice, including diet, water intake and body weight, was recorded. Vitamin D up-regulated the mRNA and protein expression of Nrf2 and MTR in mouse myocardial tissue and cells. CHIP assay determined that the combination of Nrf2 binding to the S1 site of the MTR promoter in cardiomyocytes using traditional PCR and real time PCR. Dual Luciferase Assay was applied to detect the transcriptional control of Nrf2 on MTR. The up-regulation effect of Nrf2 on MTR was verified by Nrf2 knockout and overexpression in cardiomyocytes. The role of Nrf2 in vitamin D inhibition of Hcy was revealed using Nrf2-knockdown HL-1 cells and Nrf2 heterozygous mice. Western blotting, real time PCR, IHC staining and ELISA showed that Nrf2 deficiency could restrain the increase in MTR expression and the decrease in Hcy level induced by vitamin D. The transcriptional activities of Nrf2/MTR were activated by vitamin D/VDR with a decrease in Hcy. CONCLUSION: Vitamin D/VDR upregulates MTR in an Nrf2-dependent manner, thereby reducing the risk of HHcy.

Elevated methylglyoxal levels inhibit tomato fruit ripening by preventing ethylene biosynthesis.

Methylglyoxal (MG), a toxic compound produced as a by-product of several cellular processes, such as respiration and photosynthesis, is well known for its deleterious effects, mainly through glycation of proteins during plant stress responses. However, very little is known about its impact on fruit ripening. Here, we found that MG levels are maintained at high levels in green tomato (Solanum lycopersicum L.) fruits and decline during fruit ripening despite a respiratory burst during this transition. We demonstrate that this decline is mainly mediated through a glutathione-dependent MG detoxification pathway and primarily catalyzed by a Glyoxalase I enzyme encoded by the SlGLYI4 gene. SlGLYI4 is a direct target of the MADS-box transcription factor RIPENING INHIBITOR (RIN), and its expression is induced during fruit ripening. Silencing of SlGLYI4 leads to drastic MG overaccumulation at ripening stages of transgenic fruits and interferes with the ripening process. MG most likely glycates and inhibits key enzymes such as methionine synthase and S-adenosyl methionine synthase in the ethylene biosynthesis pathway, thereby indirectly affecting fruit pigmentation and cell wall metabolism. MG overaccumulation in fruits of several nonripening or ripening-inhibited tomato mutants suggests that the tightly regulated MG detoxification process is crucial for normal ripening progression. Our results underpin a SlGLYI4-mediated regulatory mechanism by which MG detoxification controls fruit ripening in tomato.

Assessment of MTR Rs1805087 SNP as Possible Modifier of Sickle Cell Disease Severity in a Nigerian Population.

BACKGROUND: Sickle cell disease is the commonest genetic disorder in Nigeria, affecting 2-3% of an estimated population of 160 million people. The role of genetic mutations in folate cycle genes, and the variable phenotypic expressions constituting disease severity, needs to be critically examined. OBJECTIVE: This study was carried out to establish the pattern of methionine synthase gene mutations (rs1805087 SNP), and its possible association with disease severity in adults with sickle cell anaemia in Lagos, Nigeria. METHODOLOGY: This is a cross-sectional study of seventy (70) subjects with sickle cell disease (HbSS) matched for age and gender with known apparently healthy haemoglobin genotype AA (HbAA) subjects, as cases and controls respectively. Structured questionnaires were used to obtain demographic, clinical and other phenotypic data needed to compute disease severity. Pattern of MTR A2756G gene mutation and homocysteine assay (Hcy) were assessed by Polymerase Chain Reaction and Enzyme- linked Immunosorbent Assay respectively. Full blood count analysis of participants was done using the KX-21 Automated Analyzer (Sysmex Corporation, Japan). RESULTS: The mutant genotypes MTR 2756 AG/GG were recorded in 46.4% (n =55) of subjects with disease severity score >7. Elevated plasma homocysteine (HHcy) was significantly associated with disease severity among HbSS subjects (OR=17.2, CI: 3.490-86.079; p=0.0001). Conversely, no significant association was observed with the mutant genotypes MTR 2756 AG/GG and disease severity (p>0.05). CONCLUSION: While HHcy is significantly associated with phenotypic expression of HbSS, the MTR 2756 SNPs did not appear to independently influence homocysteine level or disease severity in HbSS subjects.

CONTEXTE: La drépanocytose est la maladie génétique la plus répandue au Nigeria, affectant 2 à 3 % d'une population estimée à 160 millions de personnes. Le rôle des mutations génétiques dans les gènes du cycle du folate, et les expressions phénotypiques variables constituant la gravité de la maladie, doivent être examinés de façon critique. OBJECTIF: Cette étude a été menée pour établir le schéma des mutations du gène de la méthionine synthase (rs1805087 SNP), et son association possible avec la gravité de la maladie chez les adultes atteints de drépanocytose à Lagos, au Nigeria. MÉTHODOLOGIE: Il s'agit d'une étude transversale de soixantedix (70) sujets atteints de drépanocytose (HbSS) appariés pour l'âge et le sexe avec des sujets connus apparemment sains de génotype d'hémoglobine AA (HbAA), comme cas et contrôles respectivement. Des questionnaires structurés ont été utilisés pour obtenir des données démographiques, cliniques et autres données phénotypiques nécessaires au calcul de la gravité de la maladie. Le profil de la mutation du gène MTR A2756G et le dosage de l'homocystéine (Hcy) ont été évalués respectivement par réaction en chaîne par polymérase et par test immunologique enzymatique. L'analyse de la formule sanguine complète des participants a été effectuée à l'aide de l'analyseur automatisé KX-21 (Sysmex Corporation, Japon). RÉSULTATS: Les génotypes mutants MTR 2756 AG/GG ont été enregistrés chez 46,4 % (n =55) des sujets présentant un score de gravité de la maladie > 7. L'homocystéine plasmatique élevée (HHcy) était significativement associée à la gravité de la maladie chez les sujets HbSS (OR=17,2, CI : 3,490­86,079 ; p=0,0001). À l'inverse, aucune association significative n'a été observée entre les génotypes mutants MTR 2756 AG/GG et la gravité de la maladie (p>0,05). CONCLUSION: Alors que l'HHcy est significativement associée à l'expression phénotypique de l'HbSS, les SNP MTR 2756 ne semblent pas influencer indépendamment le niveau d'homocystéine ou la gravité de la maladie chez les sujets HbSS.

The Roles of MTRR and MTHFR Gene Polymorphisms in Colorectal Cancer Survival.

BACKGROUND: Paradoxically epidemiological data illustrate a negative relationship between dietary folate intake and colorectal cancer (CRC) risk. The occurrence and progression of CRC may be influenced by variants in some key enzyme coding genes in the folate metabolic pathway. We investigated the correlation between genetic variants in methionine synthase reductase (MTRR) and methylenetetrahydrofolate reductase (MTHFR) and CRC survival. METHODS: This study used data collected from the Newfoundland Familial Colorectal Cancer Study. A total of 532 patients diagnosed with CRC for the first time from 1999 to 2003 were enrolled, and their mortality were tracked until April 2010. DNA samples were genotyped by Illumina's integrated quantum 1 million chip. Cox models were established to assess 33 tag single-nucleotide polymorphisms in MTRR and MTHFR in relation to overall survival (OS), disease-free survival (DFS) and CRC-specific survival. RESULTS: The MTRR and MTHFR genes were associated with DFS and CRC-specific survival in CRC patients at the gene level. After multiple comparison adjustment, MTRR rs1801394 A (vs. G) allele was associated with increased DFS (p = 0.024), while MTHRT rs3737966 (G vs. A), rs4846049 (T vs. G), rs1476413 (A vs. G), rs1801131 (C vs. A), rs12121543 (A vs. C), rs1801133 (C vs. T), rs4846052 (T vs. C), rs2066471 (A vs. G) and rs7533315 (T vs. C) were related to worse CRC-specific survival. Additionally, significant interactions were seen among pre-diagnostic alcohol consumption with MTRR rs1801394, rs3776467, rs326124, rs162040, and rs3776455, with superior OS associated with those protective variant alleles limited to patients with alcohol consumption under the median. The MTHFR rs3737966 (G vs. A) allele seemed to be detrimental to CRC survival only among subjects with fruit intake below the median. CONCLUSIONS: Polymorphic variants in MTRR and MTHFR genes that code for key enzymes for folate metabolism may be associated with survival in patients with CRC. The gene-CRC outcome association seems modulated by alcohol drinking and fruit intake.

Dietary-derived vitamin B12 protects Caenorhabditis elegans from thiol-reducing agents.

BACKGROUND: One-carbon metabolism, which includes the folate and methionine cycles, involves the transfer of methyl groups which are then utilised as a part of multiple physiological processes including redox defence. During the methionine cycle, the vitamin B12-dependent enzyme methionine synthetase converts homocysteine to methionine. The enzyme S-adenosylmethionine (SAM) synthetase then uses methionine in the production of the reactive methyl carrier SAM. SAM-binding methyltransferases then utilise SAM as a cofactor to methylate proteins, small molecules, lipids, and nucleic acids. RESULTS: We describe a novel SAM methyltransferase, RIPS-1, which was the single gene identified from forward genetic screens in Caenorhabditis elegans looking for resistance to lethal concentrations of the thiol-reducing agent dithiothreitol (DTT). As well as RIPS-1 mutation, we show that in wild-type worms, DTT toxicity can be overcome by modulating vitamin B12 levels, either by using growth media and/or bacterial food that provide higher levels of vitamin B12 or by vitamin B12 supplementation. We show that active methionine synthetase is required for vitamin B12-mediated DTT resistance in wild types but is not required for resistance resulting from RIPS-1 mutation and that susceptibility to DTT is partially suppressed by methionine supplementation. A targeted RNAi modifier screen identified the mitochondrial enzyme methylmalonyl-CoA epimerase as a strong genetic enhancer of DTT resistance in a RIPS-1 mutant. We show that RIPS-1 is expressed in the intestinal and hypodermal tissues of the nematode and that treating with DTT, ß-mercaptoethanol, or hydrogen sulfide induces RIPS-1 expression. We demonstrate that RIPS-1 expression is controlled by the hypoxia-inducible factor pathway and that homologues of RIPS-1 are found in a small subset of eukaryotes and bacteria, many of which can adapt to fluctuations in environmental oxygen levels. CONCLUSIONS: This work highlights the central importance of dietary vitamin B12 in normal metabolic processes in C. elegans, defines a new role for this vitamin in countering reductive stress, and identifies RIPS-1 as a novel methyltransferase in the methionine cycle.

Profiling the Influence of Gene Variants Related to Folate-Mediated One-Carbon Metabolism on the Outcome of In Vitro Fertilization (IVF) with Donor Oocytes in Recipients Receiving Folic Acid Fortification.

Nutritional status and gene polymorphisms of one-carbon metabolism confer a well-known interaction that in pregnant women may affect embryo viability and the health of the newborn. Folate metabolism directly impacts nucleotide synthesis and methylation, which is of increasing interest in the reproductive medicine field. Studies assessing the genetic influence of folate metabolism on IVF treatments have currently been performed in women using their own oocytes. Most of these patients seeking to have a child or undergoing IVF treatments are advised to preventively intake folate supplies that restore known metabolic imbalances, but the treatments could lead to the promotion of specific enzymes in specific women, depending on their genetic variance. In the present study, we assess the influence of candidate gene variants related to folate metabolism, such as Serine Hydroxymethyltransferase 1 SHMT1 (rs1979276 and rs1979277), Betaine-Homocysteine S-Methyltransferase BHMT (rs3733890), Methionine synthase reductase MTRR (rs1801394), Methylenetetrahydrofolate reductase MTHFR (rs1801131 and rs1801133), methionine synthase MTR (rs12749581), ATP Binding Cassette Subfamily B Member 1 ABCB1 (rs1045642) and folate receptor alpha FOLR1 (rs2071010) on the success of IVF treatment performed in women being recipients of donated oocytes. The implication of such gene variants seems to have no direct impact on pregnancy consecution after IVF; however, several gene variants could influence pregnancy loss events or pregnancy maintenance, as consequence of folic acid fortification.

A Hydrogen-Sulfide-Repressed Methionine Synthase SlMS1 Acts as a Positive Regulator for Fruit Ripening in Tomato.

Ethylene is a key phytohormone that regulates the ripening of climacteric fruits, and methionine is an indirect precursor of ethylene. However, whether methionine synthase plays a role in fruit ripening in Solanum lycopersicum (tomato) is still unknown. In this study, we find that a tomato methionine synthase (named SlMS1), which could be repressed at the transcriptional level by hydrogen sulfide (H2S), acts as a positive regulator for tomato fruit ripening. By a bioinformatics analysis, it is found that SlMS1 and SlMS2 in tomato are highly homologous to methionine synthases in Arabidopsis thaliana. The expression pattern of SlMS1 and SlMS2 is analyzed in tomato, and SlMS1 expression is up-regulated during fruit ripening, suggesting its potential role in regulating fruit ripening. A potential bipartite nuclear localization signal is found in the amino acid sequence of SlMS1; thus, SlMS1 is tagged with GFP and observed in the leaves of Nicotiana benthamiana. Consistently, SlMS1-GFP shows strong nuclear localization and also cytoplasmic localization. The role of SlMS1 in regulating fruit ripening is investigated in tomato fruit by transient silencing (virus-induced gene silencing, VIGS) and transient overexpression. The results show that SlMS1 silencing causes delayed fruit ripening, evidenced by more chlorophyll and less carotenoid accumulation, while SlMS1 overexpression accelerates fruit ripening significantly compared with control. Further investigation shows that SlMS1 overexpression could up-regulate the expression of carotenoid-synthesis-related genes (PSY1, PDS, ZDS), chlorophyll-degradation-related genes (NYC1, PAO, PPH, SGR1), cell-wall-metabolism-related genes (CEL2, EXP, PG, TBG4, XTH5) and ethylene-synthesis-pathway-related genes (ACO1, ACO3, ACS2), while SlMS1 silencing causes the opposite results. The correlation analysis indicates that SlMS1 expression is negatively correlated with chlorophyll content and positively correlated with carotenoid and ripening-related gene expressions. Taken together, our data suggest that SlMS1 is a positive regulator of tomato fruit ripening and a possible target gene for the ripening-delaying effect of H2S.

Association between MTR A2756G polymorphism and susceptibility to congenital heart disease: A meta-analysis.

The association between methionine synthase (MTR) A2756G (rs1805087) polymorphism and the susceptibility to congenital heart disease (CHD) has not been fully determined. A meta-analysis of case-control studies was performed to systematically evaluate the above association. Studies were identified by searching the PubMed, Embase, Web of Science, China National Knowledge Infrastructure, and WanFang databases from inception to June 20, 2021. Two authors independently performed literature search, data extraction, and quality assessment. Predefined subgroup analyses were carried out to evaluate the impact of the population ethnicity, source of healthy controls (community or hospital-based), and methods used for genotyping on the outcomes. A random-effects model was used to combine the results, and 12 studies were included. Results showed that MTR A2756G polymorphism was not associated with CHD susceptibility under the allele model (odds ratio [OR]: 0.96, 95% confidence interval [CI]: 0.86 to 1.07, P = 0.43, I2 = 4%), heterozygote model (OR: 0.95, 95% CI: 0.84 to 1.07, P = 0.41, I2 = 0%), homozygote model (OR: 1.00, 95% CI: 0.64 to 1.55, P = 0.99, I2 = 17%), dominant genetic model (OR: 0.95, 95% CI: 0.84 to 1.07, P = 0.41, I2 = 0%), or recessive genetic model (OR: 0.94, 95% CI: 0.62 to 1.43, P = 0.32, I2 = 13%). Consistent results were found in subgroup analyses between Asian and Caucasian populations in studies with community and hospital-derived controls as well as in studies with PCR-RFLP and direct sequencing (all P values for subgroup differences > 0.05). In conclusion, current evidence does not support an association between MTR A2756G polymorphism and CHD susceptibility.

Investigation of the relationship between MTRR A66G, MTR A2756G gene variations and cell anomalies in early diagnosis and progression of bladder cancer.

BACKGROUND: The aim of this study is to investigate the relationship between MTRR A66G, MTRA2756G gene variations and cell anomalies in the early diagnosis and progression of bladder cancer. METHODS: PCR and RFLP methods were used to determine the genotype distributions of MTRR A66G and MTR A2756G gene variations. Peripheral smear preparations prepared from blood samples were fixed with methanol fixative and stained histochemically. Cellular morphological evaluations were made under the light microscope. RESULTS: In our study, AA-GG haplotype was observed significantly more in the patient group than control group (OR: 3.304, 95% CI: 1.023-10.665, p = 0.046). The significant increase was determined in terms of histological damage parameters in the patient group compared to the control group (p < 0.05). For multiple vacuoles damage parameter (mild score), AA genotype of MTR A2756G gene variation was significantly different compared to AA genotype of MTRR A66G gene variation (OR: 0.211, 0.049-0.912, p = 0.037). AA genotype of MTR A2756G gene variation was observed more than AA homozygous genotype of MTR A66G gene variation for giant platelets with different sizes damage parameter (mild score) (OR: 0.062, 0.017-0.228, p < 0.001). CONCLUSIONS: In conclusion, in Thrace population, AA genotype of the MTR A2756G gene variation was significantly higher than the AA homozygous genotype of the MTR A66G gene variation as a genetic risk factor for the multiple vacuoles damage parameter. In addition, AA genotype of MTR A2756G gene variation was determined as a genetic risk factor for giant platelets with different sizes damage parameter.

"Association of MTHFR and MS/MTR gene polymorphisms with congenital heart defects in North Indian population (Jammu and Kashmir): a case-control study encompassing meta-analysis and trial sequential analysis".

BACKGROUND: The risk of Congenital Heart Defects (CHD) is greatly influenced by variants within the genes involved in folate-homocysteine metabolism. Polymorphism in MTHFR (C677T and G1793A) and MS/MTR (A2756G) genes increases the risk of developing CHD risk, but results are controversial. Therefore, we conducted a case-control association pilot study followed by an up-dated meta-analysis with trial sequential analysis (TSA) to obtain more precise estimate of the associations of these two gene variants with the CHD risk. METHODS: For case-control study, we enrolled 50 CHD patients and 100 unrelated healthy controls. Genotyping was done by PCR-RFLP method and meta-analysis was performed by MetaGenyo online Statistical Analysis System software. For meta-analysis total number of individuals was as follows: for MTHFR C677T 3450 CHD patients and 4447 controls whereas for MS A2756G 697 CHD patients and 777 controls. RESULTS: Results of the original pilot study suggested lack of association for MTHFR C677T and MS A2756G polymorphism with risk of CHD whereas MTHFR G1793A was significantly associated with the disease. On performing meta-analysis, a significant association was observed with MTHFR C677T polymorphism but not with MS A2756G. Trial sequential Analysis also confirmed the sufficient sample size requirement for findings of meta-analysis. CONCLUSIONS: The results of the meta-analysis suggested a significant role of MTHFR in increased risk of CHD.

Folate metabolism abnormalities in infertile patients with endometriosis.

Background: Homocysteine levels can be impacted by enzymes variations. Aim: To correlate MTHFR, MTR and MTRR variants with homocysteine levels in the blood and follicular fluid and assisted reproduction results. Material & methods:MTHFR (rs2274976, rs1801131, rs1801133), MTR (rs1805087) and MTRR (rs1801394) genotyping was performed by TaqMan assays and compared with homocysteine levels, measured by ELISA, to oocytes retrieved and to the pregnancy status of women with endometriosis and controls. Results: The MTR G allele and GG genotype were more common in patients with endometriosis. They also showed lower levels of homocysteine and more clinical gestations. Epistasis analysis showed a model associated with gestational results, composed of MTHFR+MTR variants (CC+AG). Conclusion: The summation effect of variants in genes participating in folate metabolism was associated with pregnancy status in Brazilian women. MTR variants were more observed in endometriosis patients, as well as lower follicular Hcy levels and increased clinical pregnancy results.

What was the aim of the study? To correlate genetic variants to homocysteine levels in the blood and oocyte surrounding fluid, and the results of assisted reproduction techniques. How was the study done? A total of 152 women with endometriosis and controls with male infertility were evaluated. DNA was extracted from blood for genetic analysis, and homocysteine levels were measured from the blood and oocyte surrounding fluid. Genetic results were correlated to homocysteine levels, oocyte quality and pregnancy status. What were the results? A specific genetic marker occurred more in endometriosis patients. They also showed lower levels of homocysteine and a tendency to more clinical gestations than controls. What do the results of the study mean? Endometriosis patients showed specific genetic markers and different levels of homocysteine compared with controls. These results can be helpful to predict gestational results.

Inherited defects of cobalamin metabolism.

Cobalamin (vitamin B12) is required for activity of the enzymes methylmalonyl-CoA mutase and methionine synthase in human cells. Inborn errors affecting cobalamin uptake or metabolism are characterized by accumulation of the substrates for these enzymes, methylmalonic acid and homocysteine, in blood and urine. Inborn errors affecting synthesis of the adenosylcobalamin coenzyme required by methylmalonyl-CoA mutase (cblA and cblB) result in isolated methylmalonic aciduria; inborn errors affecting synthesis of the methylcobalamin coenzyme required by methionine synthase (cblE and cblG) result in isolated homocystinuria. Combined methylmalonic aciduria and homocystinuria is seen in patients with impaired intestinal cobalamin absorption (intrinsic factor deficiency, Imerslund-Gräsbeck syndrome) and with defects affecting synthesis of both cobalamin coenzymes (cblC, cblD, cblF and cblJ). A series of disorders caused by pathogenic variant mutations affecting gene regulators (transcription factors) of the MMACHC gene have recently been described (HCFC1 [cblX disorder] and deficiencies of THAP11, and ZNF143 [the cblK disorder]).

MTR-G is a high-risk allele for lower-extremity arteriosclerotic occlusion.

OBJECTIVE: This study investigated the relationship between the MTRA2576G polymorphism of the key enzyme in homocysteine metabolism and deep vein thrombosis (DVT), chronic venous insufficiency (CVI) and arteriosclerotic occlusion (ASO) of the lower extremities. METHODS: Genomic DNA was extracted from the peripheral blood of patients with lower-extremity vascular diseases, including 125 cases of DVT, 125 cases of CVI and 125 cases of ASO. DNA samples extracted from 197 healthy individuals were used as control samples. PCR-RFLP was used to investigate the polymorphisms of MTR in these subjects. RESULTS: The frequency of the G allele in MTR was 6.8%, 6.1% and 12.8% for the DVT group, CVI group and ASO group, respectively (p = 0.003). The frequency of the GG allele was 13.6%, 12.2% and 22.4% for the DVT group, CVI group and ASO group, respectively (p = 0.014). Only the allele frequency of GG in the ASO group was higher than that in the control group, and the disease risk was also 1.3 times higher than that in the control group (OR = 1.299, 95% CI = 1.025 ∼ 2.575). CONCLUSION: Patients with the G allele in MTR have a high risk for ASO, and the GG allele is a risk gene for ASO.

Causes and consequences of impaired methionine synthase activity in acquired and inherited disorders of vitamin B12 metabolism.

Methyl-Cobalamin (Cbl) derives from dietary vitamin B12 and acts as a cofactor of methionine synthase (MS) in mammals. MS encoded by MTR catalyzes the remethylation of homocysteine to generate methionine and tetrahydrofolate, which fuel methionine and cytoplasmic folate cycles, respectively. Methionine is the precursor of S-adenosyl methionine (SAM), the universal methyl donor of transmethylation reactions. Impaired MS activity results from inadequate dietary intake or malabsorption of B12 and inborn errors of Cbl metabolism (IECM). The mechanisms at the origin of the high variability of clinical presentation of impaired MS activity are classically considered as the consequence of the disruption of the folate cycle and related synthesis of purines and pyrimidines and the decreased synthesis of endogenous methionine and SAM. For one decade, data on cellular and animal models of B12 deficiency and IECM have highlighted other key pathomechanisms, including altered interactome of MS with methionine synthase reductase, MMACHC, and MMADHC, endoplasmic reticulum stress, altered cell signaling, and genomic/epigenomic dysregulations. Decreased MS activity increases catalytic protein phosphatase 2A (PP2A) and produces imbalanced phosphorylation/methylation of nucleocytoplasmic RNA binding proteins, including ELAVL1/HuR protein, with subsequent nuclear sequestration of mRNAs and dramatic alteration of gene expression, including SIRT1. Decreased SAM and SIRT1 activity induce ER stress through impaired SIRT1-deacetylation of HSF1 and hypomethylation/hyperacetylation of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α), which deactivate nuclear receptors and lead to impaired energy metabolism and neuroplasticity. The reversibility of these pathomechanisms by SIRT1 agonists opens promising perspectives in the treatment of IECM outcomes resistant to conventional supplementation therapies.