Regulation of de Novo Purine Biosynthesis by Methenyltetrahydrofolate Synthetase in Neuroblastoma

Field, Martha S.; Szebenyi, Doletha M. E.; Stover, Patrick J.

doi:10.1074/jbc.m510624200

Cited by 49 publications

(68 citation statements)

References 42 publications

(37 reference statements)

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“…FDH expression had no effect on the 14 C/ 3 H ratio in nuclear DNA or purine deoxynucleosides, demonstrating that, although FDH can deplete 10-formyl-THF pools, this activity does not impair the incorporation of formate into purines (de novo purine biosynthesis) relative to salvage pathway biosynthesis in neuroblastoma (Table 4). Recently, we demonstrated that the enzyme methenyltetrahydrofolate synthetase (MTHFS) is a high affinity 10-formyl-THF-binding protein and that MTHFS-bound 10-formyl-THF enhances rates of purine biosynthesis relative to salvage pathway synthesis in SH-SY5Y cells (29). MTHFS may bind and channel 10-formyl-THF to the de novo purine biosynthesis pathway, thus protecting this pathway from FDH-mediated depletion of 10-formyl-THF pools.…”

Section: Cell Line Sam/sah Sam Sahmentioning

confidence: 99%

“…[ 14 C]Formate is incorporated into purine nucleotides through de novo purine nucleotide biosynthesis, which is folate-dependent, whereas [ 3 H]hypoxanthine is incorporated into purine nucleotides through the salvage pathway (29). FDH expression had no effect on the 14 C/ 3 H ratio in nuclear DNA or purine deoxynucleosides, demonstrating that, although FDH can deplete 10-formyl-THF pools, this activity does not impair the incorporation of formate into purines (de novo purine biosynthesis) relative to salvage pathway biosynthesis in neuroblastoma (Table 4).…”

Section: Cell Line Sam/sah Sam Sahmentioning

confidence: 99%

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Regulation of Folate-mediated One-carbon Metabolism by 10-Formyltetrahydrofolate Dehydrogenase

Anguera

Field

Perry

et al. 2006

Journal of Biological Chemistry

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10-Formyltetrahydrofolate dehydrogenase (FDH) catalyzes the NADP؉ -dependent conversion of 10-formyltetrahydrofolate to CO 2 and tetrahydrofolate (THF) and is an abundant high affinity folatebinding protein. Although several activities have been ascribed to FDH, its metabolic role in folate-mediated one-carbon metabolism is not well understood. FDH has been proposed to: 1) inhibit purine biosynthesis by depleting 10-formyl-THF pools, 2) maintain cellular folate concentrations by sequestering THF, 3) deplete the supply of folateactivated one-carbon units, and 4) stimulate the generation of THFactivated one-carbon unit synthesis by channeling folate cofactors to other folate-dependent enzymes. The metabolic functions of FDH were investigated in neuroblastoma, which do not contain detectable levels of FDH. Both low and high FDH expression reduced total cellular folate concentrations by 60%, elevated rates of folate catabolism, and depleted cellular 5-methyl-THF and S-adenosylmethionine levels. Low FDH expression increased the formyl-THF/THF ratio nearly 10-fold, whereas THF accounted for nearly 50% of total folate in neuroblastoma with high FDH expression. FDH expression did not affect the enrichment of exogenous formate into methionine, serine, or purines and did not suppress de novo purine nucleotide biosynthesis. We conclude that low FDH expression facilitates the incorporation of one-carbon units into the one-carbon pool, whereas high levels of FDH expression deplete the folate-activated one-carbon pool by catalyzing the conversion of 10-formyl-THF to THF. Furthermore, FDH does not increase cellular folate concentrations by sequestering THF in neuroblastoma nor does it inhibit or regulate de novo purine biosynthesis. FDH expression does deplete cellular 5-methyl-THF and S-adenosylmethionine levels indicating that FDH impairs the folate-dependent homocysteine remethylation cycle. Tetrahydrofolate (THF)2 polyglutamates are cofactors that function as one-carbon donors and acceptors in a set of reactions known as folate-mediated one-carbon metabolism, which occurs both in the cytoplasm and in mitochondria (see Fig. 1) (1). THF cofactors carry onecarbon units at three oxidation states ranging from formate to methanol (2). The biologically active THF derivatives contain a reduced pteridine and a polyglutamate peptide consisting of five to eight glutamate residues linked by ␥-peptide bonds (3). Cytoplasmic folate-mediated onecarbon metabolism is required for the de novo synthesis of purines (supplies the carbon-2 and carbon-8 of the purine ring) and thymidylate (methylation of dUMP to dTMP), and also for remethylation of homocysteine to methionine (2, 3). Methionine can be converted to S-adenosylmethionine (SAM) and serve as a methyl donor for numerous methylation reactions, including the methylation of DNA, RNA, and proteins. Serine is a primary source of folate-activated one-carbon units (4). Cytoplasmic serine hydroxymethyltransferase (cSHMT) catalyzes the THF-dependent aldol cleavage of serine to methylene-THF and...

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Section: Cell Line Sam/sah Sam Sahmentioning

confidence: 99%

Section: Cell Line Sam/sah Sam Sahmentioning

confidence: 99%

Regulation of Folate-mediated One-carbon Metabolism by 10-Formyltetrahydrofolate Dehydrogenase

Anguera

Field

Perry

et al. 2006

Journal of Biological Chemistry

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“…To identify genes in the folate pathway with possible impact on the metabolism of LV, the relative expression of 22 genes putatively involved in transport, polyglutamation and metabolism of LV was determined in tumor and mucosa tissue of patients with stage III colorectal cancer. A schematic representation of folate transport and folate-mediated 1-carbon metabolism in eukaryotic cells is shown in Figure 1 (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). The patients were subjected to adjuvant treatment with bolus FLV alone, or to bolus FLV plus oxaliplatin (FLOX), given according to the Nordic regimes (20,21).…”

Section: Introductionmentioning

confidence: 99%

Expression of Folate Pathway Genes in Stage III Colorectal Cancer Correlates with Recurrence Status Following Adjuvant Bolus 5-FU-Based Chemotherapy

Odin

Sondén

Gustavsson

et al. 2015

Mol Med

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Colorectal cancer is commonly treated with 5-fluorouracil and 5-formyltetrahydrofolate (leucovorin). Metabolic action of leucovorin requires several enzymatic steps that are dependent on expression of corresponding coding genes. To identify folate pathway genes with possible impact on leucovorin metabolism, a retrospective study was performed on 193 patients with stage III colorectal cancer. Relative expression of 22 genes putatively involved in leucovorin transport, polyglutamation and metabolism was determined in tumor and mucosa samples using quantitative real-time polymerase chain reaction. After surgery, patients received adjuvant 5-fluorouracil-based bolus chemotherapy with leucovorin during six months, and were followed for 3 to 5 years. Cox regression analysis showed that high tumoral expression of the genes SLC46A1/PCFT (proton-coupled folate transporter) and SLC19A1/RFC-1 (reduced folate carrier 1) correlated significantly (p < 0.001 and p < 0.01, respectively) with a decreased risk of recurrent disease, measured as disease-free survival (DFS). These two genes are involved in the transport of folates into the cells and each functions optimally at a different pH. We conclude that SLC46A1/PCFT and SLC19A1/RFC-1 are associated with DFS of patients with colorectal cancer and hypothesize that poor response to 5-fluorouracil plus leucovorin therapy in some patients may be linked to low expression of these genes. Such patients might need a more intensified therapeutic approach than those with high gene expression. Future prospective studies will determine if the expression of any of these genes can be used to predict response to leucovorin.

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“…hMTHFS has been reported to be feedback inhibited by 10-formyltetrahydrofolate (22). Analysis of the structure of the enzyme-product complex of hMTHFS reveals that the synthesis or binding of 10-formyltetrahydrofolate places the formyl group of N10 within van der Waals radii of Y83.…”

Section: Discussionmentioning

confidence: 99%

“…Attempts have been made to gain structural insights into inhibition of MTHFS based on steady-state kinetics and molecular modeling of a murine MTHFS (mMTHFS; refs. 22,23). However, the interpretation of results is limited by the accuracy of the model of mMTHFS, which was generated by using a template that shares very low sequence identity.…”

Section: Introductionmentioning

confidence: 99%

Structural Basis for the Inhibition of Human 5,10-Methenyltetrahydrofolate Synthetase by N10-Substituted Folate Analogues

Song

et al. 2009

Cancer Research

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5,10-Methenyltetrahydrofolate synthetase (MTHFS) regulates the flow of carbon through the one-carbon metabolic network, which supplies essential components for the growth and proliferation of cells. Inhibition of MTHFS in human MCF-7 breast cancer cells has been shown to arrest the growth of cells. Absence of the three-dimensional structure of human MTHFS (hMTHFS) has hampered the rational design and optimization of drug candidates. Here, we report the structures of native hMTHFS, a binary complex of hMTHFS with ADP, hMTHFS bound with the N5-iminium phosphate reaction intermediate, and an enzyme-product complex of hMTHFS. The N5-iminium phosphate captured for the first time in our crystal structure unravels a unique strategy used by hMTHFS for recognition of the substrate and provides structural basis for the regulation of enzyme activity. Binding of N10-substituted folate analogues places Y152 in the middle of the channel connecting ATP binding site with the substrate binding pocket, precluding the positioning of ;-phosphate for a nucleophilic attack. Using the structures of hMTHFS as a guide, we have probed the role of residues surrounding the active site in catalysis by mutagenesis. The ensemble of hMTHFS structures and the mutagenesis data yield a coherent picture of the MTHFS active site, determinants of substrate specificity, and new insights into the mechanism of inhibition of hMTHFS.

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Regulation of de Novo Purine Biosynthesis by Methenyltetrahydrofolate Synthetase in Neuroblastoma

Cited by 49 publications

References 42 publications

Regulation of Folate-mediated One-carbon Metabolism by 10-Formyltetrahydrofolate Dehydrogenase

Regulation of Folate-mediated One-carbon Metabolism by 10-Formyltetrahydrofolate Dehydrogenase

Expression of Folate Pathway Genes in Stage III Colorectal Cancer Correlates with Recurrence Status Following Adjuvant Bolus 5-FU-Based Chemotherapy

Structural Basis for the Inhibition of Human 5,10-Methenyltetrahydrofolate Synthetase by N10-Substituted Folate Analogues

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