One-carbon Metabolism Pathway Research Articles

Essential role of proline synthesis and the one-carbon metabolism pathways for systemic virulence of Streptococcus pneumoniae.

Virulence screens have indicated potential roles during Streptococcus pneumoniae infection for the one-carbon metabolism pathway component Fhs and proline synthesis mediated by ProABC. To define how these metabolic pathways affect S. pneumoniae virulence, we have investigated the phenotypes, transcription, and metabolic profiles of Δfhs and ΔproABC mutants. S. pneumoniae capsular serotype 6B BHN418 Δfhs and ΔproABC mutant strains had strongly reduced virulence in mouse sepsis and pneumonia models but could colonize the nasopharynx. Both mutant strains grew normally in complete media but had markedly impaired growth in chemically defined medium, human serum, and human cerebrospinal fluid. The BHN418 ΔproABC strain also had impaired growth under conditions of osmotic and oxidative stress. The virulence role of proABC was strain specific, as the D39 ΔproABC strain could still cause septicemia and grow in serum. Compared to culture in broth, in serum, the BHN418 Δfhs and ΔproABC strains showed considerable derangement in global gene transcription that affected multiple but different metabolic pathways for each mutant strain. Metabolic data suggested that Δfhs had an impaired stringent response, and when cultured in sera, BHN418 Δfhs and ΔproABC were under increased oxidative stress and had altered lipid profiles. Loss of proABC also affected carbohydrate metabolism and the accumulation of peptidoglycan synthesis precursors in the BHN418 but not the D39 background, linking this phenotype to the conditional virulence phenotype. These data identify the S. pneumoniae metabolic functions affected by S. pneumoniae one-carbon metabolism and proline biosynthesis, and the role of these genetic loci for establishing systemic infection.IMPORTANCERapid adaptation to grow within the physiological conditions found in the host environment is an essential but poorly understood virulence requirement for systemic pathogens such as Streptococcus pneumoniae. We have now demonstrated an essential role for the one-carbon metabolism pathway and a conditional role depending on strain background for proline biosynthesis for S. pneumoniae growth in serum or cerebrospinal fluid, and therefore for systemic virulence. RNAseq and metabolomic data demonstrated that the loss of one-carbon metabolism or proline biosynthesis has profound but differing effects on S. pneumoniae metabolism in human serum, identifying the metabolic processes dependent on each pathway during systemic infection. These data provide a more detailed understanding of the adaptations required by systemic bacterial pathogens in order to cause infection and demonstrate that the requirement for some of these adaptations varies between strains from the same species and could therefore underpin strain variations in virulence potential.

8815 ANPEP regulates one-carbon metabolism in prostate cancer

Abstract Disclosure: A. El-Kenawi: None. R. Putney: None. A. Berglund: None. K. Yamoah: None. African American men (AAM) experience disproportionately higher rates of both prostate cancer (PCa) incidence and mortality compared to their European American counterparts (EAM). To investigate some of the biological factors which contribute to these disparities, we carried out an unbiased genomic expression analysis of PCa by ancestry using the matched GRID and VANDAAM cohorts. In this analysis, we discovered aminopeptidase N (ANPEP, APN, CD13), to be the most differentially expressed functional gene in both self-identified and ancestry derived AAM compared with EAM. Further computational analyses revealed that ANPEP correlates with signatures of cholesterol transport, estrogen and androgen receptor (AR) signaling. The functional role of ANPEP in regulating cholesterol metabolism and AR signaling remains unclear. Further computational analyses demonstrate that expression of ANPEP predominantly correlates with various amino acid transporters. In addition, comprehensive metabolomic characterization revealed that ANPEP-overexpressing cells exhibit altered level of one-carbon metabolism metabolites. The one-carbon metabolic pathway regulates amino acids homeostasis and epigenetic mechanisms. Metabolomics-based approach to assess the consumption of over 15 amino acids in patient-derived explants validate enrichment of one-carbon metabolism circuits in AAM. Thus, we further investigated whether ANPEP impact high methylation capacity by performing genome-wide methylation profiling in cells. We unraveled that ANPEP overexpression is associated with elevated methylation of DNA. Our future studies will assess whether ANPEP regulation of methylation capacity have an impact on AR binding to DNA. Presentation: 6/3/2024

Methyl-donor supplementation in women with systemic lupus erythematosus with different nutritional status: the protocol for a randomised, double-blind, placebo-controlled trial

IntroductionDNA hypomethylation in patients with systemic lupus erythematosus (SLE) has been recently documented in the literature. Low levels of DNA methylation have been observed globally and in genes associated with...

Exposure to prenatal excess or imbalanced micronutrients leads to long-term perturbations in one-carbon metabolism, trimethylamine-N-oxide and DNA methylation in Wistar rat offspring.

Prenatal multivitamins, including folic acid, are commonly consumed in excess, whereas choline, an essential nutrient and an important source of labile methyl groups, is underconsumed. Here, we characterized profiles of one-carbon metabolism and related pathways andpatterns of DNA methylation in offspring exposed to excess or imbalanced micronutrients prenatally. Pregnant Wistar rats were fed either recommended 1× vitamins (RV), high 10× vitamins (HV), high 10× folic acid with recommended choline (HFolRC), or high 10× folic acid with no choline (HFolNC). Offspring were weaned to a high-fat diet for 12 weeks. Circulating metabolites were analyzed with a focus on the hypothalamus, an area known to be under epigenetic regulation. HV, HFolRC, and HFolNC males had higher body weight (BW) and lower plasma choline and methionine consistent with lower hypothalamic S-adenosylmethionine (SAM):S-adenosylhomocysteine (SAH) and global DNA methylation compared with RV. HV and HFolNC females had higher BW and lower plasma 5-methyltetrahydrofolate and methionine consistent with lower hypothalamic global DNA methylation compared with RV. Plasma dimethylglycine (DMG) and methionine were higher as with hypothalamic SAM:SAH and global DNA methylation in HFolRC females without changes in BW compared with RV. Plasma trimethylamine and trimethylamine-N-oxide were higher in males but lower in females from HFolRC compared with RV. Network modeling revealed a link between the folate-dependent pathway and SAH, with most connections through DMG. Final BW was negatively correlated with choline, DMG, and global DNA methylation. In conclusion, prenatal intake of excess or imbalanced micronutrients induces distinct metabolic and epigenetic perturbations in offspring that reflect long-term nutritional programming of health.

Acidity induces durable enhancement of Treg cell suppressive functions for tumor immune evasion

The microenvironment within solid tumors often becomes acidic due to various factors associated with abnormal metabolism and cellular activities, including increased lactate production as a result of dysregulated tumor glycolysis. Recently, we have identified multiple tumor microenvironment (TME) factors that potentiate regulatory T (Treg) cell function in evading anti-tumor immunosurveillance. Despite the strong correlation between lactate and acidity, the potential roles of acidity in intratumoral Treg cell adaptation and underlying molecular mechanisms have gone largely unstudied. In this study, we demonstrate that acidity significantly enhances immunosuppressive functions of nTreg cells, but not iTreg cells, without altering the expression of either FoxP3 or the cell surface receptors CD25, CTLA4, or GITR in these cells. Surprisingly, the addition of lactate, often considered a major contributor to increased acidity of the TME, completely abolished the acidity-induced enhancement of nTreg suppressive functions. Consistently, metabolic flux analyses showed elevated basal mitochondrial respiratory capacity and ATP-coupled respiration in acidity-treated nTreg cells without altering glycolytic capacity. Genome-wide transcriptome and metabolomics analyses revealed alterations in multiple metabolic pathways, particularly the one-carbon folate metabolism pathway, with reduced SAM, folate, and glutathione, in nTreg cells exposed to low pH conditions. Addition of a one-carbon metabolic contributor, formate, diminished the acidity-induced enhancement in nTreg cell suppressive functions, but neither SAM nor glutathione could reverse the phenotype. Remarkably, in vitro transient treatment of nTreg cells resulted in sustained enhancement of their functions, as evidenced by more vigorous tumor growth observed in mice adoptively receiving acidity-treated nTreg cells. Further analysis of intratumoral infiltrated T cells confirmed a significant reduction in CD8+ T cell frequency and their granzyme B production. In summary, our study elucidates how acidity-mediated metabolic reprogramming leads to sustained Treg-mediated tumor immune evasion.

Methionine Synthase 2 Represses Stem Cell Maintenance of Arabidopsis thaliana in Response to Salt Stress.

Salt stress represses the growth and development of plants that mainly depend on the continual propagation and differentiation of stem cells. WUSCHEL (WUS)/WUSCHEL-RELATED HOMEOBOX (WOX) family proteins determine stem cell fate in plants under ever-changing environments. It is not yet known how plant stem cell homeostasis is regulated under salt stress. Methionine synthase catalyzes the formation of methionine by methylating homocysteine in the one-carbon metabolism pathway. In this work, we investigated the role of Arabidopsis METHIONINE SYNTHASE 2 (AtMS2) in stem cell homeostasis under salt stress. The results showed that AtMS2 represses the stem cell maintenance of Arabidopsis in response to salt stress. Under normal growth conditions, AtMS2 is mainly localized in the cytoplasm. However, under salt stress, it exhibits significant accumulation in the nucleus. AtMS2 interacts with the WUS/WOX protein, and, together, they repress WUS/WOX expression by binding to its promoter. The mutation in AtMS2 resulted in enhanced salt tolerance. Therefore, AtMS2 might act as a key negative regulator to repress the stem cell maintenance and growth of Arabidopsis under salt stress.

Metaboepigenetic regulation of gene expression in obesity and insulin resistance.

Variation in DNA methylation (DNAm) in adipose tissue is associated with the pathogenesis of obesity and insulin resistance. The activity of enzymes involved in altering DNAm levels is dependent on several metabolite cofactors. To understand the role of metabolites as mechanistic regulators of epigenetic marks, we tested the association between selected plasma metabolites and DNAm levels in the adipose tissue of African Americans. In the AAGMEx cohort (N = 256), plasma levels of metabolites were measured by untargeted liquid chromatography-mass spectrometry; adipose tissue DNAm and transcript levels were measured by reduced representation bisulfite sequencing, and expression microarray, respectively. Among the 21 one-carbon metabolism pathway metabolites evaluated, six were associated with gluco-metabolic traits (PFDR < 0.05, for BMI, SI, or Matsuda index) in AAGMEx. Methylation levels of 196, 116, and 180 CpG-sites were associated (P < 0.0001) with S-adenosylhomocysteine (SAH), cystine, and hypotaurine, respectively. Cis-expression quantitative trait methylation (cis eQTM) analyses suggested the role of metabolite-level-associated CpG sites in regulating the expression of adipose tissue transcripts, including genes in G-protein coupled receptor signaling pathway. Plasma SAH level-associated CpG sites chr19:3403712 and chr19:3403735 were also associated with the expression of G-protein subunit alpha 15 (GNA15) in adipose. The expression of GNA15 was significantly correlated with BMI (β = 1.87, P = 1.9 × 10-16) and SI (β = -1.61, P = 2.49 × 10-5). Our study suggests that a subset of metabolites modulates the methylation levels of CpG sites in specific loci and, in turn, regulates the expression of transcripts involved in obesity and insulin resistance.

Fat and proteolysis due to methionine, tryptophan, and niacin deficiency leads to alterations in gut microbiota and immune modulation in inflammatory bowel disease.

Inflammatory bowel disease (IBD) is one of the intractable diseases. Nutritional components associated with IBD have been identified, and it is known that excessive methionine intake exacerbates inflammation, and that tryptophan metabolism is involved in inflammation. Analysis of the gut microbiota has also progressed, where Lactobacillus regulate immune cells in the intestine and suppress inflammation. However, whether the methionine and tryptophan metabolic pathways affect the growth of intestinal Lactobacillus is unknown. Here we show how transient methionine, tryptophan, and niacin deficiency affects the host and gut microbiota in mouse models of colitis (induced by dextran sodium sulfate) fed a methionine-deficient diet (1K), tryptophan and niacin-deficient diet (2K), or methionine, tryptophan, and niacin-deficient diet (3K). These diets induced body weight decrease and 16S rRNA analysis of mouse feces revealed the alterations in the gut microbiota, leading to a dramatic increase in the proportion of Lactobacillus in mice. Intestinal RNA sequencing data confirmed that the expression of several serine proteases and fat-metabolizing enzymes were elevated in mice fed with methionine, tryptophan, and niacin (MTN) deficient diet. In addition, one-carbon metabolism and peroxisome proliferator-activated receptor (PPAR) pathway activation were also induced with MTN deficiency. Furthermore, changes in the expression of various immune-related cytokines were observed. These results indicate that methionine, tryptophan, and niacin metabolisms are important for the composition of intestinal bacteria and host immunity. Taken together, MTN deficiencies may serve as a Great Reset of gut microbiota and host gene expression to return to good health.

Abstract 2756: Single cell analysis reveals treatment response-associated plastic cell state and lineage switching in aggressive variant prostate cancer

Abstract Prostate cancer (PCa) is a common malignancy in men over 65, ranking as the second leading cause of cancer-related deaths among men in the United States. While most prostate cancers respond to androgen receptor (AR) targeting therapies, Aggressive Variant Prostate Cancers (AVPCs), characterized by RB1, Tp53, and/or PTEN alterations, do not. AVPCs exhibit lineage plasticity in preclinical models, enabling the expression of non-prostate epithelial lineage markers to adapt to therapeutic pressures. However, a measurable definition of lineage plasticity as a potential therapeutic target for clinical trials is currently lacking. To arrive at said definition, we perform single-nuclei RNA sequencing (snRNA-seq) on lymph node metastases from twelve AVPC patients with matched sample pairs of both pre- and post-treatment. Additionally, we include snRNA-seq data from eight non-AVPC patients as a baseline. Expanding upon our prior establishment of tumor-specific total mRNA expression (TmS) as an indicator of tumor cell lineage plasticity (Nature Biotechnology, PMID: 35697807), we employ unique molecular identifier (UMI) counts from individual cells to quantify this plasticity. We reveal a distinct cluster of tumor cells with notably high UMI counts in resistant samples, indicative of a less differentiated state and increased transcriptional diversity. This high-UMI cluster is marked by significant enrichment in pathways associated with epithelial-mesenchymal transition (EMT), stemness, one-carbon metabolism, and arginine metabolism pathways. Concurrently, there is a reduction in activity within the androgen receptor (AR) and DNA damage repair pathways. These characteristics suggest an enhanced capacity for lineage switching in AVPC tumor cells, potentially contributing to evasion from targeted therapies. Moreover, immune components within resistant samples consistently display lower UMI counts, indicating a diminished propensity for lineage plasticity. In conclusion, we present a better understanding of lineage switching in therapeutic resistance in AVPCs, paving the way for novel treatment strategies in PCa management. Citation Format: Shuai Guo, Elavarasan Subramani, Daniel E. Frigo, Patrick G. Pilié, Sangeeta Goswami, Rama Soundararajan, Ana Aparicio, Wenyi Wang. Single cell analysis reveals treatment response-associated plastic cell state and lineage switching in aggressive variant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2756.

Serine synthesis and catabolism in starved lung cancer and primary bronchial epithelial cells

Serine and glycine give rise to important building blocks in proliferating cells. Both amino acids are either synthesized de novo or taken up from the extracellular space. In lung cancer, serine synthesis gene expression is variable, yet, expression of the initial enzyme, phosphoglycerate dehydrogenase (PHGDH), was found to be associated with poor prognosis. While the contribution of de novo synthesis to serine pools has been shown to be enhanced by serine starvation, the impact of glucose deprivation, a commonly found condition in solid cancers is poorly understood. Here, we utilized a stable isotopic tracing approach to assess serine and glycine de novo synthesis and uptake in different lung cancer cell lines and normal bronchial epithelial cells in variable serine, glycine, and glucose conditions. Under low glucose supplementation (0.2 mM, 3–5% of normal plasma levels), serine de novo synthesis was maintained or even activated. As previously reported, also gluconeogenesis supplied carbons from glutamine to serine and glycine under these conditions. Unexpectedly, low glucose treatment consistently enhanced serine to glycine conversion, along with an up-regulation of the mitochondrial one-carbon metabolism enzymes, serine hydroxymethyltransferase (SHMT2) and methylenetetrahydrofolate dehydrogenase (MTHFD2). The relative contribution of de novo synthesis greatly increased in low serine/glycine conditions. In bronchial epithelial cells, adaptations occurred in a similar fashion as in cancer cells, but serine synthesis and serine to glycine conversion, as assessed by label enrichments and gene expression levels, were generally lower than in (PHGDH positive) cancer cells. In summary, we found a variable contribution of glucose or non-glucose carbon sources to serine and glycine and a high adaptability of the downstream one-carbon metabolism pathway to variable glucose supply.

Global DNA Methylation Levels Viz-a-Viz Genetic and Biochemical Variations in One Carbon Metabolic Pathway: An Exploratory Study from North India.

Despite the importance of one carbon metabolic pathway (OCMP) in modulating the DNA methylation process, only a few population-based studies have explored their relationship among healthy individuals. This study aimed to understand the variations in global DNA methylation levels with respect to selected genetic (CBS 844ins68, MTRR A66G, MTR A2756G, and MTHFR C677T polymorphisms) and biochemical (folate, vitamin B12, and homocysteine) markers associated with OCMP among healthy North Indian adults. The study has been conducted among 1095 individuals of either sex (69.5% females), aged 30-75 years. A sample of 5 mL of blood was collected from each participant. Homocysteine, folate, and vitamin B12 levels were determined using the chemiluminescence technique. Restriction digestion was performed for genotyping MTRR A66G, MTR A2756G, and MTHFR C677T polymorphisms and allele-specific PCR amplification for CBS 844ins68 polymorphism. Global DNA methylation levels were analyzed using ELISA-based colorimetric technique. Of the selected genetic and biochemical markers, the mutant MTRR A66G allele was positively associated with global DNA methylation levels. Further, advanced age was inversely associated with methylation levels. MTRR 66GG genotype group was hypermethylated than other genotypes in folate replete and vitamin B12 deficient group (a condition prevalent among vegetarians), suggesting that the G allele may be more efficient than the wild-type allele in such conditions. Global DNA methylation levels appeared to be more influenced by genetic than biochemical factors. MTRR 66G allele may have a selective advantage in vitamin B12 deficient conditions. Further research should be undertaken to understand how genetics affects epigenetic processes.

The functional roles of S-adenosyl-methionine and S-adenosyl-homocysteine and their involvement in trisomy 21.

The one-carbon metabolism pathway is involved in critical human cellular functions such as cell proliferation, mitochondrial respiration, and epigenetic regulation. In the homocysteine-methionine cycle S-adenosyl-methionine (SAM) and S-adenosyl-homocysteine (SAH) are synthetized, and their levels are finely regulated to ensure proper functioning of key enzymes which control cellular growth and differentiation. Here we review the main biological mechanisms involving SAM and SAH and the known related human diseases. It was recently demonstrated that SAM and SAH levels are altered in plasma of subjects with trisomy 21 (T21) but how this metabolic dysregulation influences the clinical manifestation of T21 phenotype has not been previously described. This review aims at providing an overview of the biological mechanisms which are altered in response to changes in the levels of SAM and SAH observed in DS.

Abstract WP251: Dietary Methionine and Homocysteine Level Interaction and Recurrent Stroke

Background: The folate one-carbon metabolism pathway (FOCM) provides vital one-carbon units for epigenetic regulation. Genetic variants in FOCM genes may affect methionine metabolism. Elevated circulating homocysteine (Hcy), a FOCM byproduct, is linked to increased stroke risk. However, the protective effects of dietary regulation of methionine and Hcy levels against recurrent stroke are uncertain. Objective: To investigate dietary methionine (METH) and its interaction with post-methionine load Hcy levels (POST) with recurrent stroke risk; to assess if genetically determined POST and its interaction with METH predict recurrent stroke risk. Methods: We utilized the Vitamin Intervention for Stroke Prevention (VISP) trial to estimate hazards ratios of METH and its interaction with POST on recurrent stroke with a Cox proportional hazards model. We also generated a POST polygenic risk score (PRS) with ridge regression using previously identified polymorphisms, located within ALDH1L1, CPS1, GNMT, and PSPH, as indicators of FOCM function. Results: The participants (n = 2,100; 64% men) had a mean (SD) age of 67 (11) years. Ancestry consisted of 82% European, 12% African, and 5.7% Other. A small portion of participants had missing POST values (7.3%). Clinical POST (HR 1.02; 95%CI 0.98, 1.06) and its interaction with METH (HR 0.99; 95% CI 0.97, 1.01) were not associated with recurrent stroke risk. Similarly, there was no significant relationship observed between PRS POST (HR 0.96; 95%CI 0.80, 1.15) and its interaction with METH (HR 1.02; 95% CI 0.94, 1.10). Conclusion: Dietary methionine and post-methionine load Hcy levels neither interact nor predict recurrent stroke risk. Our PRS approach showed similar negative findings. The relationship of the FOCM and recurrent stroke risk may lie in epigenetics.

LAT1-dependent placental methionine uptake is a key player in fetal programming of metabolic disease

The Developmental Origins of Health and Disease hypothesis sustains that exposure to different stressors during prenatal development prepares the offspring for the challenges to be encountered after birth. We studied the gestational period as a particularly vulnerable window where different stressors can have strong implications for fetal programming of the offspring's life-long metabolic status via alterations of specific placentally expressed nutrient transporters. To study this mechanism, we used a murine prenatal stress model, human preeclampsia, early miscarriage, and healthy placental tissue samples, in addition to in vitro models of placental cells. In stressed mice, placental overexpression of L-type amino acid transporter 1 (Lat1) and subsequent global placental DNA hypermethylation was accompanied by fetal and adult hypothalamic dysregulation in global DNA methylation and gene expression as well as long-term metabolic abnormalities exclusively in female offspring. In human preeclampsia, early miscarriage, and under hypoxic conditions, placental LAT1 was significantly upregulated, leading to increased methionine uptake and global DNA hypermethylation. Remarkably, subgroups of healthy term placentas with high expression of stress-related genes presented increased levels of placental LAT1 mRNA and protein, DNA and RNA hypermethylation, increased methionine uptake capacity, one-carbon metabolic pathway disruption, higher methionine concentration in the placenta and transport to the fetus specifically in females. Since LAT1 mediates the intracellular accumulation of methionine, global DNA methylation, and one-carbon metabolism in the placenta, our findings hint at a major sex-specific global response to a variety of prenatal stressors affecting placental function, epigenetic programming, and life-long metabolic disease and provide a much-needed insight into early-life factors predisposing females/women to metabolic disorders.

Metagenomic Characterisation of the Gut Microbiome and Effect of Complementary Feeding on Bifidobacterium spp. in Australian Infants.

Complementary feeding induces dramatic ecological shifts in the infant gut microbiota toward more diverse compositions and functional metabolic capacities, with potential implications for immune and metabolic health. The aim of this study was to examine whether the age at which solid foods are introduced differentially affects the microbiota in predominantly breastfed infants compared with predominantly formula-fed infants. We performed whole-genome shotgun metagenomic sequencing of infant stool samples from a cohort of six-month-old Australian infants enrolled in a nested study within the ORIGINS Project longitudinal birth cohort. Infants born preterm or those who had been administered antibiotics since birth were excluded. The taxonomic composition was highly variable among individuals at this age. Predominantly formula-fed infants exhibited a higher microbiome diversity than predominantly breastfed infants. Among the predominantly breastfed infants, the introduction of solid foods prior to five months of age was associated with higher alpha diversity than solid food introduction after six months of age, primarily due to the loss of Bifidobacterium infantis. In contrast, the age at which solid food was introduced was not associated with the overall change in diversity among predominantly formula-fed infants but was associated with compositional changes in Escherichia abundance. Examining the functional capacity of the microbiota in relation to these changes, we found that the introduction of solid foods after six months of age was associated with elevated one-carbon compound metabolic pathways in both breastfed and formula-fed infants, although the specific metabolic sub-pathways differed, likely reflecting different taxonomic compositions. Our findings suggest that the age of commencement of solid foods influences the gut microbiota composition differently in predominantly breastfed infants than in predominantly formula-fed infants.

Exploring the complexities of 1C metabolism: implications in aging and neurodegenerative diseases.

The intricate interplay of one-carbon metabolism (OCM) with various cellular processes has garnered substantial attention due to its fundamental implications in several biological processes. OCM serves as a pivotal hub for methyl group donation in vital biochemical reactions, influencing DNA methylation, protein synthesis, and redox balance. In the context of aging, OCM dysregulation can contribute to epigenetic modifications and aberrant redox states, accentuating cellular senescence and age-associated pathologies. Furthermore, OCM's intricate involvement in cancer progression is evident through its capacity to provide essential one-carbon units crucial for nucleotide synthesis and DNA methylation, thereby fueling uncontrolled cell proliferation and tumor development. In neurodegenerative disorders like Alzheimer's and Parkinson's, perturbations in OCM pathways are implicated in the dysregulation of neurotransmitter synthesis and mitochondrial dysfunction, contributing to disease pathophysiology. This review underscores the profound impact of OCM in diverse disease contexts, reinforcing the need for a comprehensive understanding of its molecular complexities to pave the way for targeted therapeutic interventions across inflammation, aging and neurodegenerative disorders.

One-carbon metabolite supplementation increases vitamin B12, folate, and methionine cycle metabolites in beef heifers and fetuses in an energy dependent manner at day 63 of gestation.

One-carbon metabolites (OCM) are metabolites and cofactors which include folate, vitamin B12, methionine, and choline that support methylation reactions. The objectives of this study were to investigate the effects of moderate changes in maternal body weight gain in combination with OCM supplementation during the first 63 d of gestation in beef cattle on (1) B12 and folate concentrations in maternal serum (2) folate cycle intermediates in maternal and fetal liver, allantoic fluid (ALF), and amniotic fluid (AMF) and (3) metabolites involved in one-carbon metabolism and related metabolic pathways in maternal and fetal liver. Heifers were either intake restricted (RES) and fed to lose 0.23 kg/d, or fed to gain 0.60 kg/d (CON). Supplemented (+ OCM) heifers were given B12 and folate injections weekly and fed rumen-protected methionine and choline daily, while non-supplemented (-OCM) heifers were given weekly saline injections. These two treatments were combined in a 2 × 2 factorial arrangement resulting in 4 treatments: CON-OCM, CON + OCM, RES-OCM, and RES + OCM. Samples of maternal serum, maternal and fetal liver, ALF, and AMF were collected at slaughter on day 63 of gestation. Restricted maternal nutrition most notably increased (./ ≤ 0.05) the concentration of vitamin B12 in maternal serum, 5,10-methylenetetrahydrofolate and 5,10-methenyltetrahydrofolate in maternal liver, and cystathionine in the fetal liver; conversely, maternal restriction decreased (P = 0.05) 5,10-methylenetetrahydrofolate concentration in fetal liver. Supplementing OCM increased (P ≤ 0.05) the concentrations of maternal serum B12, folate, and folate intermediates, ALF and AMF 5-methyltetrahydrofolate concentration, and altered (P ≤ 0.02) other maternal liver intermediates including S-adenosylmethionine, dimethylglycine, cystathionine Glutathione reduced, glutathione oxidized, taurine, serine, sarcosine, and pyridoxine. These data demonstrate that OCM supplementation was effective at increasing maternal OCM status. Furthermore, these data are similar to previously published literature where restricted maternal nutrition also affected maternal OCM status. Altering OCM status in both the dam and fetus could impact fetal developmental outcomes and production efficiencies. Lastly, these data demonstrate that fetal metabolite abundance is highly regulated, although the changes required to maintain homeostasis may program altered metabolism postnatally.

Universality of critical active site glutamate as an acid-base catalyst in serine hydroxymethyltransferase function.

Serine hydroxymethyltransferase (SHMT) is a key enzyme in the one-carbon metabolic pathway, utilizing the vitamin B6 derivative pyridoxal 5'-phosphate (PLP) and vitamin B9 derivative tetrahydrofolate (THF) coenzymes to produce essential biomolecules. Many types of cancer utilize SHMT in metabolic reprogramming, exposing the enzyme as a compelling target for antimetabolite chemotherapies. In pursuit of elucidating the catalytic mechanism of SHMT to aid in the design of SHMT-specific inhibitors, we have used room-temperature neutron crystallography to directly determine the protonation states in a model enzyme Thermus thermophilus SHMT (TthSHMT), which exhibits a conserved active site compared to human mitochondrial SHMT2 (hSHMT2). Here we report the analysis of TthSHMT, with PLP in the internal aldimine form and bound THF-analog, folinic acid (FA), by neutron crystallography to reveal H atom positions in the active site, including PLP and FA. We observed protonated catalytic Glu53 revealing its ability to change protonation state upon FA binding. Furthermore, we obtained X-ray structures of TthSHMT-Gly/FA, TthSHMT-l-Ser/FA, and hSHMT2-Gly/FA ternary complexes with the PLP-Gly or PLP-l-Ser external aldimines to analyze the active site configuration upon PLP reaction with an amino acid substrate and FA binding. Accurate mapping of the active site protonation states together with the structural information gained from the ternary complexes allow us to suggest an essential role of the gating loop conformational changes in the SHMT function and to propose Glu53 as the universal acid-base catalyst in both THF-independent and THF-dependent activities of SHMT.

Oxidative stress-initiated one-carbon metabolism drives the generation of interleukin-10-producing B cells to resolve pneumonia.

The metabolic reprogramming underlying the generation of regulatory B cells during infectious diseases remains unknown. Using a Pseudomonas aeruginosa-induced pneumonia model, we reported that IL-10-producing B cells (IL-10+ B cells) play a key role in spontaneously resolving infection-mediated inflammation. Accumulated cytosolic reactive oxygen species (ROS) during inflammation were shown to drive IL-10+ B-cell generation by remodeling one-carbon metabolism. Depletion of the enzyme serine hydroxymethyltransferase 1 (Shmt1) led to inadequate one-carbon metabolism and decreased IL-10+ B-cell production. Furthermore, increased one-carbon flux elevated the levels of the methyl donor S-adenosylmethionine (SAM), altering histone H3 lysine 4 methylation (H3K4me) at the Il10 gene to promote chromatin accessibility and upregulate Il10 expression in B cells. Therefore, the one-carbon metabolism-associated compound ethacrynic acid (EA) was screened and found to potentially treat infectious pneumonia by boosting IL-10+ B-cell generation. Overall, these findings reveal that ROS serve as modulators to resolve inflammation by reprogramming one-carbon metabolism pathways in B cells.

Optic disc edema during strict 6° head-down tilt bed rest is related to one-carbon metabolism pathway genetics and optic cup volume.

Some astronauts on International Space Station missions experience neuroophthalmological pathologies as part of spaceflight associated neuro-ocular syndrome (SANS). Strict head-down tilt bed rest (HDTBR) is a spaceflight analog that replicates SANS findings and those who had 3-4 risk alleles (G and C alleles from the methionine synthase reductase [MTRR] A66G and serine hydroxymethyltransferase [SHMT1] C1420T, respectively) as compared to 1-2 risk alleles, had a greater increase in total retinal thickness (TRT). The objective of this study was to identify factors that contribute to the individual variability of the development of SANS in a 60d HDTBR at the German Aerospace Center's:envihab facility, Cologne Germany. 22 of 24 subjects who participated in the HDTBR study provided blood samples for genetic analysis. Total retinal thickness and optic cup volume were measured before and after bed rest. Subjects with 3-4 versus 0-2 risk alleles had greater ΔTRT during and after bed rest, and the model improved with the addition of baseline optic cup volume. This bed rest study confirms that variants of MTRR and SHMT1 are associated with ocular pathologies. Subjects with more risk alleles had the greatest HDTBR-induced ΔTRT, reaffirming that genetics predispose some individuals to developing SANS. Preflight optic cup volume and genetics better predict ΔTRT than either one alone. Whether nutritional supplements can override the genetic influences on biochemistry, physiology, and pathophysiology remains to be tested. These findings have significant implications for both aerospace and terrestrial medicine.