Dual effect of methylene-tetrahydrofolate reductase and angiotensinconverting enzyme gene polymorphisms on the risk of acute ischemic stroke.

Ischemic stroke, a prevalent neurological disease, is the major reason of serious disability and death worldwide. Methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms increase homocysteine levels which also raise the risk of vascular diseases. Angiotensin-converting enzyme (ACE) gene polymorphisms can cause vascular reorganization and disrupt arterial wall stability. The aim of this study was to explore how the MTHFR and ACE gene polymorphisms are related to acute ischemic stroke. A total of 200 individuals (102 acute ischemic stroke patients and 98 healthy controls) were included in this case-control research. MTHFR gene C677T (rs1801133) and A1298C (rs1801131) polymorphisms were studied through polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) assays, ACE gene I/D polymorphism (rs1799752) was studied by PCR. The MTHFR C667T and ACE I/D polymorphisms did not show any statistically meaningful differences between healthy controls and acute ischemic stroke patients (P>0.05). However, compared to healthy controls, acute ischemic stroke patients had almost nine-fold higher prevalence of the CC genotype based on the MTHFR A1298C polymorphism (P=0.024, OR=8.8, 95%Cl=1.27-208.2). Additionally, individuals with acute ischemic stroke had greater frequencies of the combined genotypes of MTHFR and ACE gene polymorphisms in the forms of CC/CC (C667T/A1298C), CC/ DD (A1298C/ACE I/D) and CC/CC/DD (C677T/A1298C/ACE I/D) (P = 0.027, P = 0.015 and P = 0.037, respectively). A statistically significant correlation was assessed between MTHFR gene A1298C polymorphism and acute ischemic stroke. Additionally, it was discovered that the genotype combinations of CC/CC (C667T/A1298C), CC/DD (A1298C/ACE I/D) and CC/CC/DD (C677T/A1298C/ ACE I/D) have risk-increasing effects on acute ischemic stroke. To employ these genetic variations as alternative treatments for ischemic stroke, these findings should be validated by more research.

Impact of methylene-tetrahydrofolate reductase gene C677T and A1298C polymorphisms as a risk factor for hepatitis B virus infection.

Chronic hepatitis B infection caused by Hepatitis B virus (HBV), influences over two billion people worldwide despite having an effective vaccine. With a total prevalence of 4.57%, there are 3.3 million estimated HBV carriers in Türkiye. Methylene-tetrahydrofolate reductase (MTHFR) arrange folate metabolism through nucleic acid synthesis and DNA methylation. C677T (rs1801133, p.Ala222Val) and A1298C (rs1801131, p.Glu429Ala) polymorphisms of MTHFR gene have effect of reducing the activity of enzyme. We purposed to investigate the correlation between C677T and A1298C polymorphisms of MTHFR gene with HBV infection in a Turkish population. One hundred eighteen HBV-infected participants and ninety healthy controls were incorporated in this research. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was applied to discover the genotypes of MTHFR polymorphisms. We demonstrated that T allele and CT + TT genotype frequencies of C677T polymorphism were significantly increased in HBV-infected participants than healthy controls [p = 0.015, OR (95% Cl) = 1.7 (1.11-2.79) and p = 0.020, OR (95% Cl) = 1.9 (1.10-3.42), respectively). No significant associations were noted concerning the A1298C polymorphism (p > 0.05). CC-AA composite genotype was observed to be significantly elevated in healthy controls than HBV-infected participants (32.2% vs. 13.6%, p = 0.001). In addition, the frequency of T-C haplotype was found to be considerably higher in the patient group than control group (15.8% vs 11.8%, p = 0.018). In conclusion, we found that T allele of C677T polymorphism poses a risk factor for HBV infection. We also discovered a protective impact of the CC-AA composite genotype against HBV infection and a risk effect of the T-A haplotype for HBV-infection.

Association between Methylene-Tetrahydrofolate Reductase C677T Polymorphism and Human Immunodeficiency Virus Type 1 Infection in Morocco.

Human immunodeficiency virus type 1 (HIV-1) infection varies substantially among individuals. One of the factors influencing viral infection is genetic variability. Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism is a genetic factor that has been correlated with different types of pathologies, including HIV-1. The MTHFR gene encodes the MTHFR enzyme, an essential factor in the folate metabolic pathway and in maintaining circulating folate and methionine at constant levels, thus preventing the homocysteine accumulation. Several studies have shown the role of folate on CD4+ T lymphocyte count among HIV-1 subjects. In this case-control study we aimed to determine the association between the MTHFR C677T polymorphism and HIV-1 infection susceptibility, AIDS development, and therapeutic outcome among Moroccans. The C677T polymorphism was genotyped by polymerase chain reaction followed by fragment length polymorphism digestion in 214 participants living with HIV-1 and 318 healthy controls. The results of the study revealed no statistically significant association between MTHFR C677T polymorphism and HIV-1 infection (P > .05). After dividing HIV-1 subjects according to their AIDS status, no significant difference was observed between C677T polymorphism and AIDS development (P > .05). Furthermore, regarding the treatment response outcome, as measured by HIV-1 RNA viral load and CD4+ T cell counts, no statistically significant association was found with MTHFR C677T polymorphism. We conclude that, in the genetic context of the Moroccan population, MTHFR C677T polymorphism does not affect HIV-1 infection susceptibility, AIDS development, or response to treatment. However, more studies should be done to investigate both genetic and nutritional aspects for more conclusive results.

Association of Polymorphism of the Methyl Tetrahydrofolate Reductase (MTHFR) Gene with Anti-Seizure Medication Response in Pediatric Patients in Jeddah, Saudi Arabia.

Background and ObjectivesEpilepsy is a chronic brain disease, with inherent and noninherent factors. Although over 20 anti-seizure medications (ASMs) are commercially available, nearly one-third of patients develop drug-resistant epilepsy. We evaluated the association between the clinical features and the methyl tetrahydrofolate (MTHFR) rs1801133 polymorphism and ASMs response among pediatric patients with epilepsy. Materials and Methods This was a multicenter, retrospective, case-control study of 101 children with epilepsy and 59 healthy children in Jeddah. The MTHFR rs1801133 polymorphism was genotyped using the real-time polymerase chain reaction TaqMan Genotyping Assay. Results Among the patients with epilepsy, 56 and 45 showed good and poor responses to ASMs, respectively. No significant genetic association was noted between the single-nucleotide polymorphism (SNP) rs1801133 within the MTHFR gene and the response to ASMs. However, a significant association was noted between reports of drug-induced toxicity and an increase in allele A frequencies. The MTHFR rs1801133 genotype was significantly associated with the development of electrolyte disturbance among good and poor responders to ASMs. Conclusion This is the first pharmacogenetic study of MTHFR in patients with epilepsy in Saudi Arabia that found no significant association between the MTHFR SNP rs1801133 and gene susceptibility and drug responsiveness. A larger sample size is needed for testing gene polymorphisms in the future.

Proteomic, Transcriptomic, Mutational, and Functional Assays Reveal the Involvement of Both THF and PLP Sites at the GmSHMT08 in Resistance to Soybean Cyst Nematode.

The serine hydroxymethyltransferase (SHMT; E.C. 2.1.2.1) is involved in the interconversion of serine/glycine and tetrahydrofolate (THF)/5,10-methylene THF, playing a key role in one-carbon metabolism, the de novo purine pathway, cellular methylation reactions, redox homeostasis maintenance, and methionine and thymidylate synthesis. GmSHMT08 is the soybean gene underlying soybean cyst nematode (SCN) resistance at the Rhg4 locus. GmSHMT08 protein contains four tetrahydrofolate (THF) cofactor binding sites (L129, L135, F284, N374) and six pyridoxal phosphate (PLP) cofactor binding/catalysis sites (Y59, G106, G107, H134, S190A, H218). In the current study, proteomic analysis of a data set of protein complex immunoprecipitated using GmSHMT08 antibodies under SCN infected soybean roots reveals the presence of enriched pathways that mainly use glycine/serine as a substrate (glyoxylate cycle, redox homeostasis, glycolysis, and heme biosynthesis). Root and leaf transcriptomic analysis of differentially expressed genes under SCN infection supported the proteomic data, pointing directly to the involvement of the interconversion reaction carried out by the serine hydroxymethyltransferase enzyme. Direct site mutagenesis revealed that all mutated THF and PLP sites at the GmSHMT08 resulted in increased SCN resistance. We have shown the involvement of PLP sites in SCN resistance. Specially, the effect of the two Y59 and S190 PLP sites was more drastic than the tested THF sites. This unprecedented finding will help us to identify the biological outcomes of THF and PLP residues at the GmSHMT08 and to understand SCN resistance mechanisms.

Developing a Sensitive Platform to Measure 5-Methyltetrahydrofolate in Subjects with MTHFR and PON1 Gene Polymorphisms.

Inadequate levels of 5-methyltetrahydrofolate (5-MTHF) and the T variant of MTHFR C677T have been suggested to be associated with an increased risk of developing mental illness, whereas the PON1 SNP variant provides a protective role. However, reports validating the methodology for plasma 5-MTHF levels in schizophrenia patients are limited. A sensitive LC−MS/MS system using an amide column and calibration curve was determined by dialyzed human plasma, and applied to schizophrenia patients and healthy controls in Taiwan, and the differences between the subgroups were discussed. This analysis system meets regulation criteria, and the lower limit of quantification for 5-MTHF levels was 4 nM from 200 µL plasma, within 7 min. The mean plasma 5-MTHF levels in schizophrenia patients (n = 34; 11.70 ± 10.37 nM) were lower than those in the healthy controls (n = 42; 22.67 ± 11.12 nM) significantly (p < 0.01). 5-MTHF concentrations were significantly lower in male carriers than in female carriers (18.30 ± 10.37 nM vs. 24.83 ± 11.01 nM, p < 0.05), especially in subjects who were MTHFR CT/PON1 Q allele carriers. In conclusion, this quantitative system, which employed sensitive and simple processing methods, was successfully applied, and identified that schizophrenic patients had significantly lower levels of 5-MTHF. Lower plasma 5-MTHF concentrations were observed in male subjects.

MTHFR SNPs (Methyl Tetrahydrofolate Reductase, Single Nucleotide Polymorphisms) C677T and A1298C Prevalence and Serum Homocysteine Levels in >2100 Hypofertile Caucasian Male Patients

Methylation is a crucially important ubiquitous biochemical process, which covalently adds methyl groups to a variety of molecular targets. It is the key regulatory process that determines the acquisition of imprinting and epigenetic marks during gametogenesis. Methylation processes are dependent upon two metabolic cycles, the folates and the one-carbon cycles. The activity of these two cycles is compromised by single nucleotide polymorphisms (SNPs) in the gene encoding the Methylenetetrahydrofolate reductase (MTHFR) enzyme. These SNPs affect spermatogenesis and oocyte maturation, creating cytologic/chromosomal anomalies. The two main MTHFR SNP variants C677T (c.6777C>T) and A1298C (c.1298A>C) together with serum homocysteine levels were tested in men with >3 years' duration of infertility who had failed several ART attempts with the same partner. These patients are often classified as having "idiopathic infertility". We observed that the genetic status with highest prevalence in this group is the heterozygous C677T, followed by the combined heterozygous C677T/A1298C, and then A1298C; these three variants represent 65% of our population. Only 13.1% of the patients tested are wild type (WT), C677C/A1298A). The homozygous 677TT and the combined heterozygote 677CT/1298AC groups have the highest percentage of patients with an elevated circulating homocysteine level of >15 µMolar (57.8% and 18.8%, respectively, which is highly significant for both). Elevated homocysteine is known to be detrimental to spermatogenesis, and the population with this parameter is not marginal. In conclusion, determination of these two SNPs and serum homocysteine should not be overlooked for patients with severe infertility of long duration, including those with repeated miscarriages. Patients must also be informed about pleiotropic medical implications relevant to their own health, as well as to the health of future children.

Methylene-tetrahydrofolate reductase gene C677T and A1298C polymorphisms as a risk factor for Crimean-Congo hemorrhagic fever.

Crimean-Congo hemorrhagic fever (CCHF) is a deadly viral disease. Methylene-tetrahydrofolate reductase (MTHFR) has an important role in folate metabolism, and also in the formation of new cells, DNA synthesis, repair and methylation. We aimed to examine the relationship between MTHFR gene C677T (Ala222Val, rs1801133) and A1298C (Glu429Ala, rs1801131) polymorphisms with CCHF in a Turkish population. Totally 273 participants were included in the current study. One hundred forty-one participants were CCHF patients and one hundred thirty-two participants were healthy controls. The polymerase chain reaction (PCR) and further restriction fragment length polymorphism (RFLP) assays were applied to determine the genotypes of MTHFR polymorphisms. We did not find any differences between the CCHF patients and healthy controls in terms of allele and genotype distributions of both the C677T and A1298C polymorphisms. In composite genotype analysis between different groups, the frequency of CT-AA composite genotype, which is formed by C677T-A1298C polymorphisms, was found to be significantly higher in Mild CCHF patients compared to both Severe CCHF patients and controls (p = 0.036 and p = 0.008, respectively). In conclusion, in this study, we found a relationship between CCHF and MTHFR gene polymorphisms. CT-AA composite genotype of MTHFR gene C677T and A1298C polymorphisms showed a predisposition to Mild CCHF.

The Second Class of Tetrahydrofolate (THF-II) Riboswitches Recognizes the Tetrahydrofolic Acid Ligand via Local Conformation Changes.

Riboswitches are regulatory noncoding RNAs found in bacteria, fungi and plants, that modulate gene expressions through structural changes in response to ligand binding. Understanding how ligands interact with riboswitches in solution can shed light on the molecular mechanisms of this ancient regulators. Previous studies showed that riboswitches undergo global conformation changes in response to ligand binding to relay information. Here, we report conformation switching models of the recently discovered tetrahydrofolic acid-responsive second class of tetrahydrofolate (THF-II) riboswitches in response to ligand binding. Using a combination of selective 2'-hydroxyl acylation, analyzed by primer extension (SHAPE) assay, 3D modeling and small-angle X-ray scattering (SAXS), we found that the ligand specifically recognizes and reshapes the THF-II riboswitch loop regions, but does not affect the stability of the P3 helix. Our results show that the THF-II riboswitch undergoes only local conformation changes in response to ligand binding, rearranging the Loop1-P3-Loop2 region and rotating Loop1 from a ~120° angle to a ~75° angle. This distinct conformation changes suggest a unique regulatory mechanism of the THF-II riboswitch, previously unseen in other riboswitches. Our findings may contribute to the fields of RNA sensors and drug design.

Association between serum 5-methyltetrahydrofolate and homocysteine in Chinese hypertensive participants with different MTHFR C677T polymorphisms: a cross-sectional study.

BACKGROUND AND AIMS: Clarifying the association between 5-methyltetrahydrofolate and homocysteine and the effect pattern of methylene tetrahydrofolate reductase (MTHFR C677T) may contribute to the management of homocysteine and may serve as a significant reference for a randomized controlled trial of 5-methyltetrahydrofolate intervention. This study aimed to reveal the association between these two biochemical indices. METHODS: Study population was drawn from the baseline data of the China Stroke Primary Prevention Trial (CSPPT), including 2328 hypertensive participants. 5-methyltetrahydrofolate and homocysteine were determined by stable-isotope dilution liquid chromatography-tandem mass spectrometry and automatic clinical analyzers, respectively. MTHFR C677T polymorphisms were detected using TaqMan assay. Multiple linear regression was performed to evaluate the association between serum 5-methyltetrahydrofolate and homocysteine. RESULTS: There was a significant inverse association between 5-methyltetrahydrofolate and homocysteine when 5-methyltetrahydrofolate was ≤ 10 ng/mL, and this association was modified by MTHFR C677T (per 1-ng/mL increment; All: ß = - 0.50, P <  0.001; CC: ß = - 0.14, P = 0.087; CT: ß = - 0.20, P = 0.011; TT: ß = - 1.19, P <  0.001). Moreover, the decline in trend in genotype TT participants was stronger than in genotype CC participants (P for difference <  0.001) and genotype CT participants (P for difference <  0.001), while there was no significant difference between genotype CC and genotype CT participants (P for difference = 0.757). CONCLUSIONS: Our data showed a non-linear association between serum homocysteine and 5-methyltetrahydrofolate among Chinese hypertensive adults, however, it could be inversely linearly fitted when serum 5-methyltetrahydrofolate was ≤ 10 ng/mL, and this association was modified by MTHFR C677T.

High-Level 5-Methyltetrahydrofolate Bioproduction in Bacillus subtilis by Combining Modular Engineering and Transcriptomics-Guided Global Metabolic Regulation.

5-Methyltetrahydrofolate (5-MTHF) is the predominant folate form in human plasma, which has been widely used as a nutraceutical. However, the microbial synthesis of 5-MTHF is currently inefficient, limiting green and sustainable 5-MTHF production. In this study, the Generally Regarded As Safe (GRAS) microorganism Bacillus subtilis was engineered as the 5-MTHF production host. Three precursor supply modules were first optimized by modular engineering for strengthening the supply of guanosine-5-triphosphate (GTP) and p-aminobenzoic acid (pABA). Next, the impact of genome-wide gene expression on 5-MTHF biosynthesis was evaluated using transcriptome analyses, which identified key genes for 5-MTHF production. The effects of potential genes on 5-MTHF synthesis were verified by observing the genes' up-regulated by strong promoter P566 and those down-regulated by inhibition through the clustered regularly interspaced short palindromic repeat interference (CRISPRi). Finally, a key gene for improved 5-MTHF biosynthesis, comGC, was integrated into the genome of modular engineered strain B89 for its overexpression and facilitating efficient 5-MTHF synthesis, reaching 3.41 ± 0.10 mg/L with a productivity of 0.21 mg/L/h, which was the highest level achieved by microbial synthesis. The engineered 5-MTHF-producing B. subtilis developed in this work lays the foundation of further enhancing 5-MTHF production by microbial fermentation, which can be used for isolation and purification of 5-MTHF as food and nutraceutical ingredients.

Tying the knot in the tetrahydrofolate (THF) riboswitch: A molecular basis for gene regulation.

Effective gene regulation by the tetrahydrofolate riboswitch depends not only on ligand affinity but also on the kinetics of ligand association, which involves two cooperative binding sites. We have determined a 1.9-Å resolution crystal structure of the ligand-free THF riboswitch aptamer. The pseudoknot binding site 'unwinds' in the absence of ligand, whereby the adjacent helical domains (P1, P2, and P3) become disjointed, resulting in rotation and misalignment of the gene-regulatory P1 helix with respect to P3. In contrast, the second binding site at the three-way junction, which is the first to fold, is structurally conserved between apo and holo forms. This suggests a kinetic role for this site, in which binding of the first ligand molecule to the stably folded three-way junction promotes formation of the regulatory pseudoknot site and subsequent binding of the second molecule. As such, these findings provide a molecular basis for both conformational switching and kinetic control.

Systems metabolic engineering of Bacillus subtilis for efficient biosynthesis of 5-methyltetrahydrofolate.

5-Methyltetrahydrofolate (5-MTHF) is the major form of folate in human plasma and is the only folate form that can penetrate the blood-brain barrier. It has been widely used for the prevention and treatment of various diseases. It is mainly produced by chemical synthesis. However, the low production rate cannot meet the increasing demand. In addition, chemical synthesis is potentially detrimental to the environment. Despite various microorganisms synthetizing 5-MTHF, an efficient 5-MTHF bioproduction approach is lacking because of the tight regulation of the 5-MTHF pathway and limited metabolic flux toward the folic acid pathway. In this study, the 5-MTHF synthetic pathway in Bacillus subtilis was systematically engineered to realize 5-MTHF accumulation and further improve 5-MTHF production. Specifically, the 5-MTHF synthesis pathway with dihydrofolate (DHF) as the precursor was strengthened to shift the metabolic flux to 5-MTHF biosynthesis by replacing the native yitJ gene with Escherichia coli metF, knockout of purU, and overexpressing dfrA. The intracellular level of 5-MTHF increased 26.4-fold, reaching 271.64 µg/L. Next, the 5-MTHF precursor supply pathway was strengthened by co-overexpression of folC, pabB, folE, and yciA. This resulted in a 93.2-fold improvement of the 5-MTHF titer, which reached 960.27 µg/L. Finally, the clustered regularly interspaced short palindromic repeats interference system was used to identify key genes in the competitive and catabolic pathways for repression to further shift the metabolic flux toward 5-MTHF biosynthesis. The repression of genes thyA (existing in the purine metabolic pathway), pheA (existing in the competitive metabolic pathway), trpE (existing in the competitive metabolic pathway), and panB (existing in the pantoate synthesis pathway) significantly increased the titer of 5-MTHF. By repressing the pheA gene, the 5-MTHF titer reached 1.58 mg/L, which was 153.8-fold that of the wild-type strain of B. subtilis 168. Through medium optimization, the 5-MTHF titer reached 1.78 mg/L, which was currently the highest titer of 5-MTHF in B. subtilis. Apart from the highest titer of 5-MTHF, the highest titer of total folates including 5-MTHF, 5-FTHF, folic acid, and THF could reach 3.31 mg/L, which was 8.5-fold that in B. subtilis. To the best of our knowledge, the 5-MTHF and total folate titers reported here are the highest using a Generally regarded as safe (GRAS) bacterium as the production host. Overall, this study provides a good starting point for further metabolic engineering to achieve efficient biosynthesis of 5-MTHF by GRAS bacteria.

Folate can promote the methionine-dependent reprogramming of glioblastoma cells towards pluripotency.

Methionine dependency of tumor growth, although not well-understood, is detectable by 11C-methionine positron emission tomography and may contribute to the aggressivity of glioblastomas (GBM) and meningiomas. Cytosolic folate cycle is required for methionine synthesis. Its dysregulation may influence cell reprogramming towards pluripotency. We evaluated methionine-dependent growth of monolayer (ML) cells and stem cell-like tumor spheres (TS) derived from 4 GBM (U251, U87, LN299, T98G) and 1 meningioma (IOMM-LEE) cell lines. Our data showed that for all cell lines studied, exogenous methionine is required for TS formation but not for ML cells proliferation. Furthermore, for GBM cell lines, regardless of the addition of folate cycle substrates (folic acid and formate), the level of 3 folate isoforms, 5-methytetrahydrofolate, 5,10-methenyltetrahydrofolate, and 10-formyltetrahydrofolate, were all downregulated in TS relative to ML cells. Unlike GBM cell lines, in IOMM-LEE cells, 5-methyltetrahydrofolate was actually more elevated in TS than ML, and only 5,10-methenyltetrahydrofolate and 10-formyltetrahydrofolate were downregulated. The functional significance of this variation in folate cycle repression was revealed by the finding that Folic Acid and 5-methyltetrahydrofolate promote the growth of U251 TS but not IOMM-LEE TS. Transcriptome-wide sequencing of U251 cells revealed that DHFR, SHMT1, and MTHFD1 were downregulated in TS vs ML, in concordance with the low activity cytosolic folate cycle observed in U251 TS. In conclusion, we found that a repressed cytosolic folate cycle underlies the methionine dependency of GBM and meningioma cell lines and that 5-methyltetrahydrofolate is a key metabolic switch for glioblastoma TS formation. The finding that folic acid facilitates TS formation, although requiring further validation in diseased human tissues, incites to investigate whether excessive folate intake could promote cancer stem cells formation in GBM patients.

Relationship between folate concentration and expression of folate-associated genes in tissue and plasma after intraoperative administration of leucovorin in patients with colorectal cancer.

PURPOSE: The aim of study was to investigate the relationship between folate concentration and expression of folate-associated genes in tumour, mucosa and plasma of patients with colorectal cancer, after intraoperative administration of bolus leucovorin (LV). METHODS: Eighty patients were randomized into four groups to receive 0, 60, 200, or 500 mg/m2 LV, respectively. Tissue and plasma folate concentrations were assessed by LC-MS/MS. Gene expression of ABCC3/MRP3, FPGS, GGH, MTHFD1L, SLC46A1/PCFT, and SLC19A1/RFC-1 was determined using quantitative PCR. RESULTS: The folate concentration in tumour increased with increasing dosage of LV. Half of the patients treated with 60 mg/m2 did not reach a level above the levels of untreated patients. A significant correlation between folate concentration in tumour and mucosa was found in untreated patients, and in the group treated with 60 mg/m2 LV. The 5-MTHF/LV ratio correlated negatively with folate concentration in mucosa, whereas a positive correlation was found in tumour of patients who received 200 or 500 mg/m2 LV. A positive correlation was found between folate concentration and expression of all genes, except MTHFD1L, in patients who received LV. There was a negative correlation between 5-MTHF concentration in plasma of untreated patients and expression of GGH and SLC46A1/PCFT in tumour. CONCLUSIONS: The results indicate the possibility of using the individual plasma 5-MTHF/LV ratio after LV injection as a surrogate marker for tissue folate concentration. Expression of several folate-associated genes is associated with folate concentration in tissue and plasma and may become useful when predicting response to LV treatment.

Functional characterization of missense mutations in severe methylenetetrahydrofolate reductase deficiency using a human expression system.

5,10-Methylenetetrahydrofolate reductase (MTHFR) catalyzes the NADPH-dependent reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate using FAD as the cofactor. Severe MTHFR deficiency is the most common inborn error of folate metabolism, resulting in hyperhomocysteinemia and homocystinuria. Approximately 70 missense mutations have been described that cause severe MTHFR deficiency, however, in most cases their mechanism of dysfunction remains unclear. Few studies have investigated mutational specific defects; most of these assessing only activity levels from a handful of mutations using heterologous expression. Here, we report the in vitro expression of 22 severe MTHFR missense mutations and two known single nucleotide polymorphisms (p.Ala222Val, p.Thr653Met) in human fibroblasts. Significant reduction of MTHFR activity (<20 % of wild-type) was observed for five mutant proteins that also had highly reduced protein levels on Western blot analysis. The remaining mutations produced a spectrum of enzyme activity levels ranging from 22-122 % of wild-type, while the SNPs retained wild-type-like activity levels. We found increased thermolability for p.Ala222Val and seven disease-causing mutations all located in the catalytic domain, three of which also showed FAD responsiveness in vitro. By contrast, six regulatory domain mutations and two mutations clustering around the linker region showed increased thermostability compared to wild-type protein. Finally, we confirmed decreased affinity for NADPH in individual mutant enzymes, a result previously described in primary patient fibroblasts. Our expression study allows determination of significance of missense mutations in causing deleterious loss of MTHFR protein and activity, and is valuable in detection of aberrant kinetic parameters, but should not replace investigations in native material.

The effect of parental 5,10-methylenetetrahydrofolate reductase 677C/T and 1298A/C gene polymorphisms on response to single-dose methotrexate in tubal ectopic pregnancy.

OBJECT: The aim of this study was to assess the effect of parental 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms (677C/T and 1298A/C) on response to single-dose methotrexate (MTX) treatment in tubal ectopic pregnancy (TEP). MATERIALS AND METHODS: In this prospective cohort study, cases with unruptured TEPs were grouped into two according to their response to single-dose MTX treatment (Group 1: responsive, n:88; Group 2: unresponsive, n:21). The groups were compared with regard to baseline demographic and clinical parameters. As a main outcome measure, the independent effects of parental MTHFR gene polymorphisms on response to single dose MTX treatment were evaluated. RESULTS: One hundred and nine unruptured TEP were included in the final analysis. The mean maternal age was 29.30 ± 5.21 years, gravity 2 (min-max: 1-5), parity 1 (min-max: 0-4). The median serum beta-human chorionic gonadotropin (ß-hCG) was 1403.35 MI/I (Q1-Q3: 517-2564). The overall response rate was 81% (88/109). The groups were similar with respect to basic baseline demographic data and serum ß-hCG level. Binary logistic regression analysis showed that the presence of parental MTHFR677C/T and 1298A/C polymorphism were not independent factor predicting treatment success (p > 0.05). The only independent factor for resistance to single dose MTX was the previous TEP (OR: 4.47 (1.18-16.9)). CONCLUSION: Parental MTHFR 677C/T and 1298A/C mutations do not predict the outcome of single dose intramuscular MTX treatment in unruptured TEP.

Homocysteinemia due to MTHFR deficiency in a young adult presenting with bilateral lens subluxations.

The most common cause of isolated inherited homocysteinemia is a deficiency of the enzyme cystathionine ß-synthase (CBS). Clinical manifestations of CBS deficiency can include ectopia lentis, thromboembolism, marfanoid habits, and intellectual disability. CBS deficiency, which affects the transsulfuration pathway, is marked biochemically by elevated serum homocysteine and plasma methionine. We report a patient with homocysteinemia, low plasma methionine, and no significant neurological abnormalities who presented with bilateral subluxated crystalline lenses due to a 5,10-methylenetetrahydrofolate reductase (MTHFR) deficiency. MTHFR deficiency, a disorder in the remethylation pathway, can cause mild to severe disease, although most presentations include neurological involvement. MTHFR deficiency has not been previously associated with lens subluxation or complete dislocation. Prolonged exposure to elevated serum homocysteine levels is most likely the explanation for her ectopia lentis. This case expands the differential diagnosis of homocysteinemia and highlights the need for a correct diagnosis to optimize the clinical outcome of patients with this condition.

Genome Characteristics of Two Novel Type I Methanotrophs Enriched from North Sea Sediments Containing Exclusively a Lanthanide-Dependent XoxF5-Type Methanol Dehydrogenase.

Microbial methane oxidizers play a crucial role in the oxidation of methane in marine ecosystems, as such preventing the escape of excessive methane to the atmosphere. Despite the important role of methanotrophs in marine ecosystems, only a limited number of isolates are described, with only four genomes available. Here, we report on two genomes of gammaproteobacterial methanotroph cultures, affiliated with the deep-sea cluster 2, obtained from North Sea sediment. Initial enrichments using methane as sole source of carbon and energy and mimicking the in situ conditions followed by serial subcultivations and multiple extinction culturing events over a period of 3 years resulted in a highly enriched culture. The draft genomes of the methane oxidizer in both cultures showed the presence of genes typically found in type I methanotrophs, including genes encoding particulate methane monooxygenase (pmoCAB), genes for tetrahydromethanopterin (H4MPT)- and tetrahydrofolate (H4F)-dependent C1-transfer pathways, and genes of the ribulose monophosphate (RuMP) pathway. The most distinctive feature, when compared to other available gammaproteobacterial genomes, is the absence of a calcium-dependent methanol dehydrogenase. Both genomes reported here only have a xoxF gene encoding a lanthanide-dependent XoxF5-type methanol dehydrogenase. Thus, these genomes offer novel insight in the genomic landscape of uncultured diversity of marine methanotrophs.

Effect of adjunctive L-methylfolate 15 mg among inadequate responders to SSRIs in depressed patients who were stratified by biomarker levels and genotype: results from a randomized clinical trial.

OBJECTIVE: Specific genetic or biological markers may predict inadequate response to therapy for major depressive disorder (MDD). The objective of the current post hoc analysis was to evaluate the effect of specific biological and genetic markers on the antidepressant efficacy of adjunctive L-methylfolate 15 mg versus placebo from a trial of inadequate responders to selective serotonin reuptake inhibitors (SSRIs). METHOD: The double-blind, randomized, placebo-controlled trial used the sequential parallel comparison design. Outpatients with SSRI-resistant MDD (DSM-IV criteria) received L-methylfolate 15 mg/d for 60 days, placebo for 30 days followed by L-methylfolate 15 mg/d for 30 days, or placebo for 60 days. The effects of baseline levels of select biological and genetic markers individually and combined on treatment response to L-methylfolate versus placebo were evaluated; the primary response measure was the 28-Item Hamilton Depression Rating Scale (HDRS-28). The first patient was enrolled July 14, 2009, and the last patient completed April 28, 2011. RESULTS: Seventy-five patients were enrolled. Patients with specific biological (body mass index ≥ 30 kg/m², elevated plasma levels of high-sensitivity C-reactive protein or 4-hydroxy-2-nonenal, low S-adenosylmethionine/S-adenosylhomocysteine ratio) and genetic markers at baseline had significantly (P ≤ .05) greater pooled mean change from baseline on the HDRS-28 with L-methylfolate versus placebo. Pooled mean change from baseline on the Clinical Global Impressions-Severity of Illness scale was significantly (P < .05) greater with L-methylfolate versus placebo for most genetic markers. Most combinations of baseline biological and genetic markers predicted significantly (P ≤ .05) greater reductions in pooled mean change from baseline in HDRS-28 scores with L-methylfolate versus placebo. CONCLUSIONS: Biomarkers associated with inflammation or metabolism and genomic markers associated with L-methylfolate synthesis and metabolism may identify patients with SSRI-resistant depression who are responsive to adjunctive therapy with L-methylfolate 15 mg. Confirmatory studies are needed. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00955955.