Affinage

SHMT1

Serine hydroxymethyltransferase, cytosolic · UniProt P34896

Length
483 aa
Mass
53.1 kDa
Annotated
2026-06-10
42 papers in source corpus 15 papers cited in narrative 15 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 8/8 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

SHMT1 is a cytoplasmic PLP-dependent serine hydroxymethyltransferase that channels folate-derived one-carbon units into de novo thymidylate biosynthesis and thereby safeguards genome integrity during DNA replication (PMID:21406397, PMID:19513116). During S-phase, SHMT1 is sumoylated and imported into the nucleus, where it assembles with thymidylate synthase (TYMS) and dihydrofolate reductase (DHFR) into a multi-enzyme thymidylate synthesis complex; SHMT1 acts as the scaffold that holds this complex together, and the L474F polymorphism that impairs its sumoylation blocks nuclear translocation (PMID:19513116, PMID:25132602). Loss of SHMT1 activity diminishes thymidylate synthesis capacity, leading to uracil misincorporation into DNA and p53-dependent apoptosis (PMID:25412303, PMID:19513116). SHMT1 enzymatic activity is allosterically controlled by RNA: it binds SHMT2 mRNA, which competes with polyglutamylated folates and switches the tetrameric enzyme's reactivity toward serine, a mechanism resolved by cryo-EM that identified a flap motif and the tetrameric assembly as required for RNA binding (PMID:38996576, PMID:34136101). In disease models, SHMT1 represses oxidative stress by suppressing NADPH oxidase components — limiting NOX1-mediated ROS to restrain hepatocellular carcinoma migration and EMT, and limiting NOX4/CYBA-driven oxidative stress to prevent osteo-/chondrogenic transdifferentiation and vascular calcification (PMID:30755243, PMID:30071536). SHMT1 also physically interacts with PEMT in astrocytes, coupling one-carbon flux to SAM homeostasis and H3K4 methylation (PMID:41262011). Its expression is transcriptionally controlled, with HOXD8 binding the SHMT1 promoter to drive expression in renal cell carcinoma (PMID:37752684). Genetically, Shmt1 disruption in mice causes folate-responsive neural tube defects and impaired hippocampal neurogenesis, establishing SHMT1-dependent thymidylate biosynthesis as causally required for neural development (PMID:21346092, PMID:22134951, PMID:23700346).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2009 High

    Establishing where and how thymidylate is made: this work showed SHMT1 supplies one-carbon units for nuclear de novo dTMP synthesis and assembles with TYMS and DHFR into a sumoylation-dependent nuclear complex during S-phase.

    Evidence Intact nuclei dUMP→dTMP biochemical assay, pharmacological SHMT inhibition, Shmt1 knockout mice, subcellular fractionation and nuclear import assays

    PMID:19513116

    Open questions at the time
    • Functional redundancy with SHMT2α leaves ~25% activity in knockouts, complicating loss-of-function interpretation
    • Structural basis of complex assembly not resolved
    • In vivo significance of L474F sumoylation defect not tested
  2. 2011 High

    Defined the metabolic specificity of SHMT1: it partitions one-carbon flux preferentially toward thymidylate rather than methylation or purine synthesis, and is causally required for neural tube closure under folate stress.

    Evidence Shmt1 hemizygous and knockout mouse models, biochemical thymidylate synthesis assays, dietary folate/choline manipulation, embryo phenotyping

    PMID:21346092 PMID:21406397 PMID:22134951

    Open questions at the time
    • Mechanism by which thymidylate insufficiency disrupts neural tube closure not detailed
    • Human relevance of mouse NTD phenotype not established
    • Tissue-specific flux partitioning not mapped
  3. 2013 Medium

    Extended SHMT1's developmental role to the brain: thymidylate biosynthesis, not folate availability per se, is required for maturation of newborn hippocampal neurons and memory.

    Evidence Shmt1 hemizygous mice, BrdU/NeuN neurogenesis assay, trace fear conditioning, dietary folate intervention

    PMID:23700346

    Open questions at the time
    • Cell-autonomous vs non-autonomous mechanism not resolved
    • Link between dTMP supply and neuronal maturation step unknown
    • Single-lab behavioral readout
  4. 2014 Medium

    Connected SHMT1 loss to a defined genotoxic outcome and to complex integrity: knockdown causes uracil misincorporation and p53-dependent apoptosis, and SHMT1 acts as a scaffold whose loss disintegrates the thymidylate synthesis complex.

    Evidence siRNA knockdown (including VB6-coupled delivery), cell cycle/apoptosis analysis, uracil incorporation assay, xenograft model

    PMID:25132602 PMID:25412303

    Open questions at the time
    • Scaffolding role characterized indirectly via complex disintegration, not by direct structural mapping
    • Generality beyond cancer cell lines untested
    • Single lab per finding
  5. 2018 Medium

    Revealed a moonlighting redox-suppressive function: SHMT1 limits NADPH-oxidase-driven oxidative stress, controlling smooth muscle transdifferentiation/calcification and cancer cell migration/EMT.

    Evidence siRNA knockdown in primary aortic smooth muscle and HCC cells, NOX1/NOX4/CYBA expression, ROS measurement, antioxidant and NOX1 rescue experiments, metastasis model

    PMID:30071536 PMID:30755243

    Open questions at the time
    • Whether ROS suppression is metabolic (GSH/one-carbon-derived) or a direct effect on NOX expression not disentangled
    • Molecular link between SHMT1 and NOX transcription unknown
    • Single lab per context
  6. 2021 Medium

    Identified SHMT1 as an RNA-binding riboregulated enzyme: binding of SHMT2 mRNA acts as a metabolic switch shaping compartmental serine and glycine levels.

    Evidence Protein-RNA interaction assays, stochastic dynamic modeling, validation in H1299 lung adenocarcinoma cells

    PMID:34136101

    Open questions at the time
    • Structural mechanism of RNA modulation not resolved here
    • Physiological conditions favoring RNA over folate binding unclear
  7. 2024 High

    Resolved the structural basis of RNA allostery: cryo-EM showed SHMT2 mRNA competes with polyglutamylated folates at the tetrameric enzyme via a flap motif, selectively altering serine reactivity.

    Evidence Cryo-EM of free and RNA-bound human SHMT1, in vitro enzymatic and RNA-binding assays, allosteric competition experiments

    PMID:38996576

    Open questions at the time
    • In vivo regulatory consequences of the allosteric switch not measured
    • RNA specificity beyond SHMT2 mRNA not defined
  8. 2025 Medium

    Placed SHMT1 in transcriptional and protein-interaction networks beyond thymidylate metabolism: HOXD8 and ZNF526 drive its expression in cancers, and SHMT1-PEMT interaction couples one-carbon flux to SAM/histone methylation in astrocytes.

    Evidence ChIP and overexpression/knockdown assays, Co-IP, 13C-serine tracing, astrocyte-specific conditional knockout, H3K4me1 ChIP, PD and tumor mouse models

    PMID:37752684 PMID:41262011 PMID:41267037

    Open questions at the time
    • ZNF526 link rests on Low-confidence single-lab data with limited orthogonal validation
    • Direct vs indirect nature of SHMT1-PEMT functional coupling not fully resolved
    • Reciprocal regulation among these factors unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unresolved how the nuclear thymidylate-synthesis, RNA-allostery, and cytoplasmic ROS-suppression functions of SHMT1 are coordinated within a single cell and which is dominant in a given tissue or disease.
  • No unified model integrating metabolic, scaffolding, and riboregulatory roles
  • Direct biochemical mechanism linking SHMT1 to NOX expression unknown
  • Human disease genetics beyond mouse NTD models not established in this corpus

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016740 transferase activity 3 GO:0003723 RNA binding 2 GO:0060090 molecular adaptor activity 2
Localization
GO:0005634 nucleus 2 GO:0005829 cytosol 2
Pathway
R-HSA-1430728 Metabolism 2 R-HSA-69306 DNA Replication 2 R-HSA-8953854 Metabolism of RNA 2
Complex memberships
nuclear de novo thymidylate synthesis complex (SHMT1/TYMS/DHFR)

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2024 Cryo-EM structures of human SHMT1 in free and RNA-bound states revealed that an RNA modulator (SHMT2 mRNA) competes with polyglutamylated folates and acts as an allosteric switch, selectively altering the enzyme's reactivity toward serine. The tetrameric assembly and a flap structural motif were identified as key structural elements required for RNA binding to eukaryotic SHMT1. Cryo-EM structure determination, in vitro enzymatic assays, RNA-binding assays, allosteric competition experiments Molecular cell High 38996576
2009 SHMT1 (cytoplasmic serine hydroxymethyltransferase) and SHMT2α (a cytoplasmic/nuclear isoform encoded by Shmt2 lacking exon 1) are functionally redundant in nuclear de novo thymidylate biosynthesis during S-phase. Purified intact mouse liver nuclei convert dUMP to dTMP in the presence of NADPH and serine; SHMT inhibitor (aminomethylphosphonate) abolishes this activity. Nuclei from Shmt1−/− mice retain ~25% of thymidylate synthesis activity due to SHMT2α. Intact nuclei biochemical assay (dUMP→dTMP conversion), pharmacological inhibition, Shmt1 knockout mouse model, subcellular fractionation/localization PloS one High 19513116
2009 SHMT1 undergoes sumoylation and nuclear import during S-phase, along with thymidylate synthase (TYMS) and dihydrofolate reductase (DHFR), forming the nuclear de novo thymidylate synthesis complex. The SHMT1 L474F polymorphism impairs SHMT1 sumoylation and nuclear translocation. Subcellular fractionation, nuclear import assay, genetic variant functional analysis PloS one Medium 19513116
2011 SHMT1 regulates partitioning of folate-derived one-carbon units toward thymidylate biosynthesis. Shmt1 hemizygosity decreases thymidylate synthesis capacity and downregulates thymidylate synthase and cytoplasmic thymidine kinase protein levels, without significant effects on methylation capacity or purine synthesis. Shmt1 hemizygous mouse model (Apcmin/+ background), biochemical thymidylate synthesis assay, protein expression analysis Cancer research Medium 21406397
2011 Disruption of Shmt1 in mice causes neural tube defects (exencephaly) under folate-deficient conditions. Dietary folate deficiency alone (without choline deficiency) is sufficient to induce NTDs in Shmt1−/− embryos, establishing SHMT1-dependent thymidylate biosynthesis as causally involved in neural tube closure. Shmt1 knockout mouse model, dietary intervention (folate-deficient vs. choline-deficient diets), embryo phenotyping The American journal of clinical nutrition High 21346092 22134951
2014 SHMT1 knockdown in lung cancer cells leads to increased uracil misincorporation into DNA and p53-dependent apoptosis. The apoptotic effect is not due to serine or glycine starvation but specifically to impaired thymidylate biosynthesis causing uracil accumulation during DNA replication. siRNA knockdown, cell cycle analysis, uracil incorporation assay, apoptosis assay (flow cytometry), p53 pathway analysis Cell death & disease Medium 25412303
2014 SHMT1 functions as a scaffold protein for a multi-enzyme complex in the de novo thymidylate biosynthesis pathway. SHMT1 knockdown via VB6-coupled siRNA delivery disintegrates this complex, causing cell cycle arrest and decreased genomic DNA content in cancer cells. SHMT1 is a vitamin B6 (PLP)-dependent enzyme, and cancer cells exploit facilitated diffusion of VB6 for continuous SHMT1 activation. siRNA knockdown via VB6-coupled polymer vector, cell cycle analysis, apoptosis assay, xenograft mouse model Biomaterials Medium 25132602
2013 Shmt1 disruption in mice impairs hippocampal neurogenesis: Shmt1+/− mice show elevated DG proliferation but a 98% reduction in mature newborn neurons and a 45% reduction in mnemonic recall during trace fear conditioning. Dietary folate manipulation alone does not rescue these phenotypes, implicating thymidylate biosynthesis (rather than folate availability per se) in neuronal maturation. Shmt1 knockout/hemizygous mouse model, BrdU/NeuN neurogenesis assay, trace fear conditioning behavioral test, dietary intervention The Journal of nutrition Medium 23700346
2019 SHMT1 inhibits hepatocellular carcinoma cell migration and invasion by repressing NOX1-mediated ROS production. SHMT1 knockdown enhances ROS production via upregulation of NOX1, promoting EMT and MMP2 expression; NOX1 was identified as a downstream target of SHMT1. Rescue experiments confirmed NOX1 mediates SHMT1's functional influence on HCC cells. Gain/loss-of-function (overexpression/siRNA knockdown), Transwell migration/invasion assay, ROS measurement, western blotting, lung metastasis mouse model, rescue experiments Journal of experimental & clinical cancer research : CR Medium 30755243
2018 SHMT1 silencing in human aortic smooth muscle cells induces osteo-/chondrogenic transdifferentiation and promotes calcification. This occurs at least in part by decreasing total antioxidant capacity and upregulating NOX4 and CYBA (NADH/NADPH oxidase components), increasing oxidative stress. Antioxidant treatment (TEMPOL or TIRON) blunts osteogenic marker induction, placing SHMT1 upstream of oxidative stress in this pathway. siRNA knockdown in primary human aortic smooth muscle cells, alkaline phosphatase activity assay, osteogenic marker mRNA expression, antioxidant rescue experiment Kidney & blood pressure research Medium 30071536
2021 SHMT1 protein binds SHMT2 mRNA, constituting a riboregulatory interaction in lung cancer cells. This SHMT1-RNA interaction shapes serine and glycine levels across cellular compartments, as modeled computationally and validated experimentally in H1299 lung adenocarcinoma cells. RNA acts as a metabolic switch for SHMT1 enzymatic activity. Protein-RNA interaction assay, stochastic dynamic modeling, experimental validation in H1299 cell line Computational and structural biotechnology journal Medium 34136101
2023 The transcription factor HOXD8 directly binds to the SHMT1 promoter (at the −456 to −254 bp region) and promotes SHMT1 expression in renal cell carcinoma. HOXD8 knockdown decreases SHMT1 expression and accelerates RCC growth, while SHMT1 overexpression suppresses RCC proliferation and migration. ChIP assay (HOXD8 binding to SHMT1 promoter), knockdown/overexpression, proliferation and migration assays, in vivo mouse tumor model Cancer science Medium 37752684
2025 SHMT1 physically interacts with PEMT (phosphatidylethanolamine N-methyltransferase) in astrocytes. Disruption of the SHMT1–PEMT interaction depletes SAM, causes H3K4me1 hypomethylation, reduces Slc1a2 and Glul expression, and exacerbates neuroexcitotoxicity and dopaminergic neuron loss in a Parkinson's disease mouse model. Astrocyte-specific conditional Shmt1 knockout decreases SAM levels and worsens PD motor phenotype. Co-immunoprecipitation/protein interaction assay, isotopic labeling (13C-serine tracing), astrocyte-specific conditional knockout, ChIP (H3K4me1), behavioral assays in PD mouse model Advanced science Medium 41262011
2025 ZNF526 transcriptionally activates SHMT1 expression in triple-negative breast cancer cells. SHMT1 activation by ZNF526 enhances flux through the serine-glycine-one-carbon (SGOC) metabolic pathway, increases glutathione (GSH) production, reduces ROS levels, and strengthens antioxidant defenses to facilitate TNBC progression. Overexpression/knockdown functional assays, metabolic flux analysis, GSH/ROS measurement, transcriptional regulation assays Molecular cancer Low 41267037
2024 Fibronectin extra domain A (FN-EDA) derived from cancer-associated fibroblasts stimulates SHMT1 upregulation in HCC cells via the TLR4/NF-κB signaling pathway, thereby countering sorafenib-induced oxidative stress and promoting sorafenib resistance. In vitro co-culture/treatment experiments, in vivo xenograft model with primary CAFs, pathway inhibition, RNA-seq analysis of HCC organoids Genes & diseases Medium 39286657

Source papers

Stage 0 corpus · 42 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2009 SHMT1 and SHMT2 are functionally redundant in nuclear de novo thymidylate biosynthesis. PloS one 161 19513116
2014 SHMT1 knockdown induces apoptosis in lung cancer cells by causing uracil misincorporation. Cell death & disease 105 25412303
2011 Shmt1 and de novo thymidylate biosynthesis underlie folate-responsive neural tube defects in mice. The American journal of clinical nutrition 92 21346092
2006 Increased expression of cSHMT, Tbx3 and utrophin in plasma of ovarian and breast cancer patients. International journal of cancer 63 16049973
2019 SHMT1 inhibits the metastasis of HCC by repressing NOX1-mediated ROS production. Journal of experimental & clinical cancer research : CR 59 30755243
2011 Shmt1 heterozygosity impairs folate-dependent thymidylate synthesis capacity and modifies risk of Apc(min)-mediated intestinal cancer risk. Cancer research 52 21406397
2007 Association of MTHFR C677T and SHMT(1) C1420T with susceptibility to ESCC and GCA in a high incident region of Northern China. Cancer causes & control : CCC 47 17206530
2011 Dietary folate, but not choline, modifies neural tube defect risk in Shmt1 knockout mice. The American journal of clinical nutrition 44 22134951
2015 miR-198 targets SHMT1 to inhibit cell proliferation and enhance cell apoptosis in lung adenocarcinoma. Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine 42 26553359
2010 SHMT1 1420 and MTHFR 677 variants are associated with rectal but not colon cancer. BMC cancer 37 20920350
2019 MiR-218-5p Suppresses the Killing Effect of Natural Killer Cell to Lung Adenocarcinoma by Targeting SHMT1. Yonsei medical journal 34 31124332
2014 Nucleotide biosynthesis arrest by silencing SHMT1 function via vitamin B6-coupled vector and effects on tumor growth inhibition. Biomaterials 27 25132602
2013 Disruption of shmt1 impairs hippocampal neurogenesis and mnemonic function in mice. The Journal of nutrition 21 23700346
2021 Modelling of SHMT1 riboregulation predicts dynamic changes of serine and glycine levels across cellular compartments. Computational and structural biotechnology journal 18 34136101
2012 Impact of SHMT1 polymorphism on the clinical outcome of patients with metastatic colorectal cancer treated with first-line FOLFIRI+bevacizumab. Pharmacogenetics and genomics 18 22044939
2009 No association between cSHMT genotypes and the risk of breast cancer in the Nurses' Health Study. European journal of clinical nutrition 16 19707223
2023 HOXD8 suppresses renal cell carcinoma growth by upregulating SHMT1 expression. Cancer science 15 37752684
2018 Role of Cytosolic Serine Hydroxymethyl Transferase 1 (SHMT1) in Phosphate-Induced Vascular Smooth Muscle Cell Calcification. Kidney & blood pressure research 15 30071536
2016 Association of SHMT1 gene polymorphisms with the risk of childhood acute lymphoblastic leukemia in a sample of Iranian population. Cellular and molecular biology (Noisy-le-Grand, France) 15 26950450
2010 Analysis of strain-dependent prepulse inhibition points to a role for Shmt1 (SHMT1) in mice and in schizophrenia. Journal of neurochemistry 15 20977478
2024 Structure-based mechanism of riboregulation of the metabolic enzyme SHMT1. Molecular cell 14 38996576
2013 DNMT3B C46359T and SHMT1 C1420T polymorphisms in the folate pathway in carcinogenesis of head and neck. Molecular biology reports 14 24362509
2015 SHMT1 C1420T polymorphism contributes to the risk of non-Hodgkin lymphoma: evidence from 7309 patients. Chinese journal of cancer 13 26666829
2014 Association between cytosolic serine hydroxymethyltransferase (SHMT1) gene polymorphism and cancer risk: a meta-analysis. Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie 12 25194438
2017 Interaction between Maternal and Paternal SHMT1 C1420T Predisposes to Neural Tube Defects in the Fetus: Evidence from Case-Control and Family-Based Triad Approaches. Birth defects research 10 28762673
2024 Cancer-associated fibroblasts derived fibronectin extra domain A promotes sorafenib resistance in hepatocellular carcinoma cells by activating SHMT1. Genes & diseases 9 39286657
2023 Rice stripe virus nonstructural protein 3 suppresses plant defence responses mediated by the MEL-SHMT1 module. Molecular plant pathology 9 37404045
2018 Association of SHMT1, MAZ, ERG, and L3MBTL3 Gene Polymorphisms with Susceptibility to Multiple Sclerosis. Biochemical genetics 9 30456721
2023 Identification of AGXT2, SHMT1, and ACO2 as important biomarkers of acute kidney injury by WGCNA. PloS one 8 36735737
2012 Role of polymorphic variants of MTR gene A2756G and SHMT1 gene C1420T in the development of prostatic cancer in residents of the Western Siberian Region of Russia. Bulletin of experimental biology and medicine 8 22803112
2019 A SHMT1 variant decreases the risk of nonsyndromic cleft lip with or without cleft palate in Chile. Oral diseases 7 31713293
2020 Evaluation of LKB1 and Serine-Glycine Metabolism Pathway Genes (SHMT1 and GLDC) Expression in AML. Indian journal of hematology & blood transfusion : an official journal of Indian Society of Hematology and Blood Transfusion 5 33867731
2013 A meta-analysis of the C1420T polymorphism in cytosolic serine hydroxymethyltransferase (SHMT1) among Caucasian colorectal cancer populations. International journal of colorectal disease 5 23322534
2025 Integrative bioinformatics approach identifies novel drug targets for hyperaldosteronism, with a focus on SHMT1 as a promising therapeutic candidate. Scientific reports 4 39799159
2023 A first-in-class dimethyl 2-acetamido terephthalate inhibitor targeting Conyza canadensis SHMT1 with a novel herbicidal mode-of-action. Journal of advanced research 2 37820886
2025 miR-944 inhibits malignant progression of bladder cancer through ATIC/AKT/FOXO3 A axis mediated by SHMT1. In vitro cellular & developmental biology. Animal 1 40442541
2017 Interaction between Maternal and Paternal SHMT1 C1420T Predisposes to Neural Tube Defects in the Fetus: Evidence from Case-Control and Family-Based Triad Approaches. Birth defects research 1 28411382
2010 [Analysis of mouse strain-dependent prepulse inhibition points to a role for Shmt1 (SHMT1) in mice and in schizophrenia]. Nihon shinkei seishin yakurigaku zasshi = Japanese journal of psychopharmacology 1 21226315
2025 Light-Regulated Reprogramming in Moss: SHMT1 Mediates Blue Light Enhancement of Cell Regeneration. Plant, cell & environment 0 40665554
2025 Upregulation of deubiquitinase UBP16 induced by rice stripe virus infection stabilizes SHMT1 to suppress ROS accumulation and facilitate virus infection in Nicotiana benthamiana. Stress biology 0 41139149
2025 Alternative Pathway for Methyl Supply through the Coupling of SHMT1 and PEMT to Maintain Astrocytic Homeostasis in Parkinson's Disease. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 0 41262011
2025 ZNF526 drives tumor growth by enhancing SHMT1-dependent serine metabolism and antioxidant capability in TNBC. Molecular cancer 0 41267037

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