1
|
Activated Brown Adipose Tissue Releases Exosomes Containing Mitochondrial Methylene Tetrahydrofolate Dehydrogenase (NADP-dependent) 1-Like Protein (MTHFD1L). Biosci Rep 2022; 42:231255. [PMID: 35502767 PMCID: PMC9142831 DOI: 10.1042/bsr20212543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 04/05/2022] [Accepted: 04/29/2022] [Indexed: 11/29/2022] Open
Abstract
Brown adipose tissue (BAT) is a promising weapon to combat obesity and metabolic disease. BAT is thermogenic and consumes substantial amounts of glucose and fatty acids as fuel for thermogenesis and energy expenditure. To study BAT function in large human longitudinal cohorts, safe and precise detection methodologies are needed. Although regarded a gold standard, the foray of PET-CT into BAT research and clinical applications is limited by its high ionizing radiation doses. Here, we show that brown adipocytes release exosomes in blood plasma that can be utilized to assess BAT activity. In the present study, we investigated circulating protein biomarkers that can accurately and reliably reflect BAT activation triggered by cold exposure, capsinoids ingestion and thyroid hormone excess in humans. We discovered an exosomal protein, methylene tetrahydrofolate dehydrogenase (NADP+ dependent) 1-like (MTHFD1L), to be overexpressed and detectable in plasma for all three modes of BAT activation in human subjects. This mitochondrial protein is packaged as a cargo within multivesicular bodies of the endosomal compartment and secreted as exosomes via exocytosis from activated brown adipocytes into the circulation. To support MTHFD1L as a conserved BAT activation response in other vertebrates, we examined a rodent model and also proved its presence in blood of rats following BAT activation by cold exposure. Plasma concentration of exosomal MTHFD1L correlated with human BAT activity as confirmed by PET-MR in humans and supported by data from rats. Thus, we deduce that MTHFD1L appears to be overexpressed in activated BAT compared to BAT in the basal nonstimulated state.
Collapse
|
2
|
Folylpoly-ɣ-glutamate synthetase association to the cytoskeleton: Implications to folate metabolon compartmentalization. J Proteomics 2021; 239:104169. [PMID: 33676037 DOI: 10.1016/j.jprot.2021.104169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 02/03/2021] [Accepted: 02/19/2021] [Indexed: 11/23/2022]
Abstract
Folates are essential for nucleotide biosynthesis, amino acid metabolism and cellular proliferation. Following carrier-mediated uptake, folates are polyglutamylated by folylpoly-ɣ-glutamate synthetase (FPGS), resulting in their intracellular retention. FPGS appears as a long isoform, directed to mitochondria via a leader sequence, and a short isoform reported as a soluble cytosolic protein (cFPGS). However, since folates are labile and folate metabolism is compartmentalized, we herein hypothesized that cFPGS is associated with the cytoskeleton, to couple folate uptake and polyglutamylation and channel folate polyglutamates to metabolon compartments. We show that cFPGS is a cytoskeleton-microtubule associated protein: Western blot analysis revealed that endogenous cFPGS is associated with the insoluble cellular fraction, i.e., cytoskeleton and membranes, but not with the cytosol. Mass spectrometry analysis identified the putative cFPGS interactome primarily consisting of microtubule subunits and cytoskeletal motor proteins. Consistently, immunofluorescence microscopy with cytosol-depleted cells demonstrated the association of cFPGS with the cytoskeleton and unconventional myosin-1c. Furthermore, since anti-microtubule, anti-actin cytoskeleton, and coatomer dissociation-inducing agents yielded perinuclear pausing of cFPGS, we propose an actin- and microtubule-dependent transport of cFPGS between the ER-Golgi and the plasma membrane. These novel findings support the coupling of folate transport with polyglutamylation and folate channeling to intracellular metabolon compartments. SIGNIFICANCE: FPGS, an essential enzyme catalyzing intracellular folate polyglutamylation and efficient retention, was described as a soluble cytosolic enzyme in the past 40 years. However, based on the lability of folates and the compartmentalization of folate metabolism and nucleotide biosynthesis, we herein hypothesized that cytoplasmic FPGS is associated with the cytoskeleton, to couple folate transport and polyglutamylation as well as channel folate polyglutamates to biosynthetic metabolon compartments. Indeed, using complementary techniques including Mass-spectrometry proteomics and fluorescence microscopy, we show that cytoplasmic FPGS is associated with the cytoskeleton and unconventional myosin-1c. This novel cytoskeletal localization of cytoplasmic FPGS supports the dynamic channeling of polyglutamylated folates to metabolon compartments to avoid oxidation and intracellular dilution of folates, while enhancing folate-dependent de novo biosynthesis of nucleotides and DNA/protein methylation.
Collapse
|
3
|
He Z, Wang X, Zhang H, Liang B, Zhang J, Zhang Z, Yang Y. High expression of folate cycle enzyme MTHFD1L correlates with poor prognosis and increased proliferation and migration in colorectal cancer. J Cancer 2020; 11:4213-4221. [PMID: 32368304 PMCID: PMC7196253 DOI: 10.7150/jca.35014] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 11/03/2019] [Indexed: 12/14/2022] Open
Abstract
Aims: To investigate the expression and clinical significance of methylenetetrahydrofolate dehydrogenase 1-like (MTHFD1L) in colorectal cancer (CRC) and its effect on CRC cells proliferation and migration. Methods: 59 fresh CRC tissue samples and matched normal tissues, 176 archive CRC tissue samples and 8 CRC cell lines were tested MTHFD1L by western blot and immunohistochemistry, respectively. The relationship between MTHFD1L expression, clinical significance and prognosis was analyzed by chi-square test and survival analysis. MTT assay, plate clonal formation assay and scratch assay were used to verify the effect of MTHFD1L on the proliferation and migration in CRC cell lines. Results: The results showed that the protein level of MTHFD1L in CRC was significantly higher than that in adjacent normal tissues (p<0.01). The expression of MTHFD1L in CRC was positively correlated with the degree of tumor differentiation, TNM classification, tumor invasion, lymph node metastasis, and distant metastasis. Survival analysis showed that CRC patients with high MTHFD1L expression had a lower 5-year survival rate and the expression of MTHFD1L was an independent adverse factor for the CRC prognosis (p<0.05). Down-regulation of MTHFD1L inhibited the proliferation and migration of DLD-1 and HCT116 CRC cell lines. Conclusion: These findings reveal that MTHFD1L is highly expressive in CRC and associated with poor prognosis, and MTHDF1L can increase colorectal cancer cell proliferation and migration. Therefore, MTHFD1L may serve as a predictor and a potential therapeutic target for CRC.
Collapse
Affiliation(s)
- Zhongyun He
- Department of Pathology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, PR, China
| | - Xia Wang
- Department of Pathology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, PR, China
| | - Huizhong Zhang
- Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, PR, China
| | - Baoxia Liang
- Department of Radiology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, PR, China
| | - Jinling Zhang
- Department of Radiology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, PR, China
| | - Zhenfeng Zhang
- Department of Radiology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, PR, China
| | - Yi Yang
- Department of Pathology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, PR, China.,Boba Evergrande International Hospital, Qionghai, PR, China
| |
Collapse
|
4
|
Fischl H, Neve J, Wang Z, Patel R, Louey A, Tian B, Furger A. hnRNPC regulates cancer-specific alternative cleavage and polyadenylation profiles. Nucleic Acids Res 2019; 47:7580-7591. [PMID: 31147722 PMCID: PMC6698646 DOI: 10.1093/nar/gkz461] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/29/2019] [Accepted: 05/15/2019] [Indexed: 02/06/2023] Open
Abstract
Alternative cleavage and polyadenylation (APA) can occur at more than half of all human genes, greatly enhancing the cellular repertoire of mRNA isoforms. As these isoforms can have altered stability, localisation and coding potential, deregulation of APA can disrupt gene expression and this has been linked to many diseases including cancer progression. How APA generates cancer-specific isoform profiles and what their physiological consequences are, however, is largely unclear. Here we use a subcellular fractionation approach to determine the nuclear and cytoplasmic APA profiles of successive stages of colon cancer using a cell line-based model. Using this approach, we show that during cancer progression specific APA profiles are established. We identify that overexpression of hnRNPC has a critical role in the establishment of APA profiles characteristic for metastatic colon cancer cells, by regulating poly(A) site selection in a subset of genes that have been implicated in cancer progression including MTHFD1L.
Collapse
Affiliation(s)
- Harry Fischl
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Jonathan Neve
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Zhiqiao Wang
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Radhika Patel
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Alastair Louey
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Bin Tian
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School and Rutgers Cancer Institute of New Jersey, Newark, NJ 07103, USA
| | - Andre Furger
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| |
Collapse
|
5
|
Shin M, Vaughn A, Momb J, Appling DR. Deletion of neural tube defect-associated gene Mthfd1l causes reduced cranial mesenchyme density. Birth Defects Res 2019; 111:1520-1534. [PMID: 31518072 DOI: 10.1002/bdr2.1591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/17/2019] [Accepted: 08/26/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND Periconceptional intake of supplemental folic acid can reduce the incidence of neural tube defects by as much as 70%, but the mechanisms by which folic acid supports cellular processes during neural tube closure are unknown. The mitochondrial 10-formyl-tetrahydrofolate synthetase MTHFD1L catalyzes production of formate, thus generating one-carbon units for cytoplasmic processes. Deletion of Mthfd1l causes embryonic lethality, developmental delay, and neural tube defects in mice. METHODS To investigate the role of mitochondrial one-carbon metabolism during cranial neural tube closure, we have analyzed cellular morphology and function in neural tissues in Mthfd1l knockout embryos. RESULTS The head mesenchyme showed significantly lower cellular density in Mthfd1l nullizygous embryos compared to wildtype embryos during the process of neural tube closure. Apoptosis and neural crest cell specification were not affected by deletion of Mthfd1l. Sections from the cranial region of Mthfd1l knockout embryos exhibited decreased cellular proliferation, but only after completion of neural tube closure. Supplementation of pregnant dams with formate improved mesenchymal density and corrected cell proliferation in the nullizygous embryos. CONCLUSIONS Deletion of Mthfd1l causes decreased density in the cranial mesenchyme and this defect is improved with formate supplementation. This study reveals a mechanistic link between folate-dependent mitochondrially produced formate, head mesenchyme formation and neural tube defects.
Collapse
Affiliation(s)
- Minhye Shin
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas
| | - Amanda Vaughn
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas
| | - Jessica Momb
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas
| | - Dean R Appling
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas
| |
Collapse
|
6
|
Bryant JD, Sweeney SR, Sentandreu E, Shin M, Ipas H, Xhemalce B, Momb J, Tiziani S, Appling DR. Deletion of the neural tube defect-associated gene Mthfd1l disrupts one-carbon and central energy metabolism in mouse embryos. J Biol Chem 2018; 293:5821-5833. [PMID: 29483189 DOI: 10.1074/jbc.ra118.002180] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 02/23/2018] [Indexed: 11/06/2022] Open
Abstract
One-carbon (1C) metabolism is a universal folate-dependent pathway essential for de novo purine and thymidylate synthesis, amino acid interconversion, universal methyl-donor production, and regeneration of redox cofactors. Homozygous deletion of the 1C pathway gene Mthfd1l encoding methylenetetrahydrofolate dehydrogenase (NADP+-dependent) 1-like, which catalyzes mitochondrial formate production from 10-formyltetrahydrofolate, results in 100% penetrant embryonic neural tube defects (NTDs), underscoring the central role of mitochondrially derived formate in embryonic development and providing a mechanistic link between folate and NTDs. However, the specific metabolic processes that are perturbed by Mthfd1l deletion are not known. Here, we performed untargeted metabolomics on whole Mthfd1l-null and wildtype mouse embryos in combination with isotope tracer analysis in mouse embryonic fibroblast (MEF) cell lines to identify Mthfd1l deletion-induced disruptions in 1C metabolism, glycolysis, and the TCA cycle. We found that maternal formate supplementation largely corrects these disruptions in Mthfd1l-null embryos. Serine tracer experiments revealed that Mthfd1l-null MEFs have altered methionine synthesis, indicating that Mthfd1l deletion impairs the methyl cycle. Supplementation of Mthfd1l-null MEFs with formate, hypoxanthine, or combined hypoxanthine and thymidine restored their growth to wildtype levels. Thymidine addition alone was ineffective, suggesting a purine synthesis defect in Mthfd1l-null MEFs. Tracer experiments also revealed lower proportions of labeled hypoxanthine and inosine monophosphate in Mthfd1l-null than in wildtype MEFs, suggesting that Mthfd1l deletion results in increased reliance on the purine salvage pathway. These results indicate that disruptions of mitochondrial 1C metabolism have wide-ranging consequences for many metabolic processes, including those that may not directly interact with 1C metabolism.
Collapse
Affiliation(s)
| | - Shannon R Sweeney
- Nutritional Sciences and the Dell Pediatric Research Institute, The University of Texas at Austin, Austin, Texas 78712
| | - Enrique Sentandreu
- Nutritional Sciences and the Dell Pediatric Research Institute, The University of Texas at Austin, Austin, Texas 78712
| | - Minhye Shin
- From the Departments of Molecular Biosciences and
| | - Hélène Ipas
- From the Departments of Molecular Biosciences and
| | | | - Jessica Momb
- From the Departments of Molecular Biosciences and
| | - Stefano Tiziani
- Nutritional Sciences and the Dell Pediatric Research Institute, The University of Texas at Austin, Austin, Texas 78712
| | | |
Collapse
|
7
|
Petschner P, Gonda X, Baksa D, Eszlari N, Trivaks M, Juhasz G, Bagdy G. Genes Linking Mitochondrial Function, Cognitive Impairment and Depression are Associated with Endophenotypes Serving Precision Medicine. Neuroscience 2018; 370:207-217. [DOI: 10.1016/j.neuroscience.2017.09.049] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 08/01/2017] [Accepted: 09/25/2017] [Indexed: 12/15/2022]
|
8
|
Eszlari N, Kovacs D, Petschner P, Pap D, Gonda X, Elliott R, Anderson IM, Deakin JFW, Bagdy G, Juhasz G. Distinct effects of folate pathway genes MTHFR and MTHFD1L on ruminative response style: a potential risk mechanism for depression. Transl Psychiatry 2016; 6:e745. [PMID: 26926881 PMCID: PMC4872445 DOI: 10.1038/tp.2016.19] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 12/14/2015] [Accepted: 01/14/2016] [Indexed: 12/11/2022] Open
Abstract
Alterations in the folate pathway have been related to both major depression and cognitive inflexibility; however, they have not been investigated in the genetic background of ruminative response style, which is a form of perseverative cognition and a risk factor for depression. In the present study, we explored the association of rumination (measured by the Ruminative Responses Scale) with polymorphisms of two distinct folate pathway genes, MTHFR rs1801133 (C677T) and MTHFD1L rs11754661, in a combined European white sample from Budapest, Hungary (n=895) and Manchester, United Kingdom (n=1309). Post hoc analysis investigated whether the association could be replicated in each of the two samples, and the relationship between folate pathway genes, rumination, lifetime depression and Brief Symptom Inventory depression score. Despite its functional effect on folate metabolism, the MTHFR rs1801133 showed no effect on rumination. However, the A allele of MTHFD1L rs11754661 was significantly associated with greater rumination, and this effect was replicated in both the Budapest and Manchester samples. In addition, rumination completely mediated the effects of MTHFD1L rs11754661 on depression phenotypes. These findings suggest that the MTHFD1L gene, and thus the C1-THF synthase enzyme of the folate pathway localized in mitochondria, has an important effect on the pathophysiology of depression through rumination, and maybe via this cognitive intermediate phenotype on other mental and physical disorders. Further research should unravel whether the reversible metabolic effect of MTHFD1L is responsible for increased rumination or other long-term effects on brain development.
Collapse
Affiliation(s)
- N Eszlari
- Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary,MTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary,Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, 1089 Budapest, Nagyvarad ter 4, Budapest 1089, Hungary. E-mail:
| | - D Kovacs
- Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary,MTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - P Petschner
- Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary,MTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - D Pap
- Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary,MTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - X Gonda
- Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary,MTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary,Department of Clinical and Theoretical Mental Health, Kutvolgyi Clinical Center, Semmelweis University, Budapest, Hungary
| | - R Elliott
- Neuroscience and Psychiatry Unit, School of Community Based Medicine, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK,Manchester Academic Health Sciences Centre, Manchester, UK
| | - I M Anderson
- Neuroscience and Psychiatry Unit, School of Community Based Medicine, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK,Manchester Academic Health Sciences Centre, Manchester, UK
| | - J F W Deakin
- Neuroscience and Psychiatry Unit, School of Community Based Medicine, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK,Manchester Academic Health Sciences Centre, Manchester, UK,Manchester Mental Health and Social Care Trust, Manchester, UK
| | - G Bagdy
- Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary,MTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - G Juhasz
- Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary,MTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary,Neuroscience and Psychiatry Unit, School of Community Based Medicine, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK,Manchester Academic Health Sciences Centre, Manchester, UK,MTA-SE-NAP B Genetic Brain Imaging Migraine Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| |
Collapse
|
9
|
Minguzzi S, Selcuklu SD, Spillane C, Parle-McDermott A. An NTD-associated polymorphism in the 3' UTR of MTHFD1L can affect disease risk by altering miRNA binding. Hum Mutat 2014; 35:96-104. [PMID: 24123340 DOI: 10.1002/humu.22459] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 09/25/2013] [Indexed: 11/11/2022]
Abstract
Maternal folate levels and polymorphisms in folate-related genes are known risk factors for neural tube defects (NTDs). SNPs in the mitochondrial folate gene MTHFD1L are associated with the risk of NTDs. We investigated whether different alleles of SNP rs7646 in the 3' UTR of MTHFD1L can be differentially regulated by microRNAs affecting MTHFD1L expression. We previously reported that miR-9 targets MTHFD1L and now we identify miR-197 as an additional miRNA regulator. Both of these miRNAs have predicted binding sites in the MTHFD1L 3' UTR in the region containing SNP rs7646. We have determined whether the alleles of SNP rs7646 (A/G) and miRNA expression levels affect miRNA binding preferences for the MTHFD1L 3' UTR and consequently MTHFD1L expression. Our results indicate that miR-9 and miR-197 specifically downregulate MTHFD1L levels in HEK293 and MCF-7 cells and that SNPrs7646 significantly affects miR-197 binding affinity to the MTHFD1L 3' UTR, causing more efficient posttranscriptional gene repression in the presence of the allele that is associated with increased risk of NTDs. These results reveal that the association of SNP rs7646 and NTD risk involves differences in microRNA regulation and, highlights the importance of genotype-dependent differential microRNA regulation in relation to human disease risk.
Collapse
Affiliation(s)
- Stefano Minguzzi
- Nutritional Genomics Group, School of Biotechnology, Dublin City University, Dublin, Ireland
| | | | | | | |
Collapse
|
10
|
Shin M, Bryant JD, Momb J, Appling DR. Mitochondrial MTHFD2L is a dual redox cofactor-specific methylenetetrahydrofolate dehydrogenase/methenyltetrahydrofolate cyclohydrolase expressed in both adult and embryonic tissues. J Biol Chem 2014; 289:15507-17. [PMID: 24733394 DOI: 10.1074/jbc.m114.555573] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian mitochondria are able to produce formate from one-carbon donors such as serine, glycine, and sarcosine. This pathway relies on the mitochondrial pool of tetrahydrofolate (THF) and several folate-interconverting enzymes in the mitochondrial matrix. We recently identified MTHFD2L as the enzyme that catalyzes the oxidation of 5,10-methylenetetrahydrofolate (CH2-THF) in adult mammalian mitochondria. We show here that the MTHFD2L enzyme is bifunctional, possessing both CH2-THF dehydrogenase and 5,10-methenyl-THF cyclohydrolase activities. The dehydrogenase activity can use either NAD(+) or NADP(+) but requires both phosphate and Mg(2+) when using NAD(+). The NADP(+)-dependent dehydrogenase activity is inhibited by inorganic phosphate. MTHFD2L uses the mono- and polyglutamylated forms of CH2-THF with similar catalytic efficiencies. Expression of the MTHFD2L transcript is low in early mouse embryos but begins to increase at embryonic day 10.5 and remains elevated through birth. In adults, MTHFD2L is expressed in all tissues examined, with the highest levels observed in brain and lung.
Collapse
Affiliation(s)
- Minhye Shin
- From the Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712
| | - Joshua D Bryant
- From the Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712
| | - Jessica Momb
- From the Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712
| | - Dean R Appling
- From the Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712
| |
Collapse
|
11
|
Kelemen O, Convertini P, Zhang Z, Wen Y, Shen M, Falaleeva M, Stamm S. Function of alternative splicing. Gene 2013; 514:1-30. [PMID: 22909801 PMCID: PMC5632952 DOI: 10.1016/j.gene.2012.07.083] [Citation(s) in RCA: 515] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Almost all polymerase II transcripts undergo alternative pre-mRNA splicing. Here, we review the functions of alternative splicing events that have been experimentally determined. The overall function of alternative splicing is to increase the diversity of mRNAs expressed from the genome. Alternative splicing changes proteins encoded by mRNAs, which has profound functional effects. Experimental analysis of these protein isoforms showed that alternative splicing regulates binding between proteins, between proteins and nucleic acids as well as between proteins and membranes. Alternative splicing regulates the localization of proteins, their enzymatic properties and their interaction with ligands. In most cases, changes caused by individual splicing isoforms are small. However, cells typically coordinate numerous changes in 'splicing programs', which can have strong effects on cell proliferation, cell survival and properties of the nervous system. Due to its widespread usage and molecular versatility, alternative splicing emerges as a central element in gene regulation that interferes with almost every biological function analyzed.
Collapse
Affiliation(s)
- Olga Kelemen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Paolo Convertini
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhaiyi Zhang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Yuan Wen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Manli Shen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Marina Falaleeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| |
Collapse
|
12
|
Deletion of Mthfd1l causes embryonic lethality and neural tube and craniofacial defects in mice. Proc Natl Acad Sci U S A 2012; 110:549-54. [PMID: 23267094 DOI: 10.1073/pnas.1211199110] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Maternal supplementation with folic acid is known to reduce the incidence of neural tube defects (NTDs) by as much as 70%. Despite the strong clinical link between folate and NTDs, the biochemical mechanisms through which folic acid acts during neural tube development remain undefined. The Mthfd1l gene encodes a mitochondrial monofunctional 10-formyl-tetrahydrofolate synthetase, termed MTHFD1L. This gene is expressed in adults and at all stages of mammalian embryogenesis with localized regions of higher expression along the neural tube, developing brain, craniofacial structures, limb buds, and tail bud. In both embryos and adults, MTHFD1L catalyzes the last step in the flow of one-carbon units from mitochondria to cytoplasm, producing formate from 10-formyl-THF. To investigate the role of mitochondrial formate production during embryonic development, we have analyzed Mthfd1l knockout mice. All embryos lacking Mthfd1l exhibit aberrant neural tube closure including craniorachischisis and exencephaly and/or a wavy neural tube. This fully penetrant folate-pathway mouse model does not require feeding a folate-deficient diet to cause this phenotype. Maternal supplementation with sodium formate decreases the incidence of NTDs and partially rescues the growth defect in embryos lacking Mthfd1l. These results reveal the critical role of mitochondrially derived formate in mammalian development, providing a mechanistic link between folic acid and NTDs. In light of previous studies linking a common splice variant in the human MTHFD1L gene with increased risk for NTDs, this mouse model provides a powerful system to help elucidate the specific metabolic mechanisms that underlie folate-associated birth defects, including NTDs.
Collapse
|
13
|
Selcuklu SD, Donoghue MTA, Rehmet K, de Souza Gomes M, Fort A, Kovvuru P, Muniyappa MK, Kerin MJ, Enright AJ, Spillane C. MicroRNA-9 inhibition of cell proliferation and identification of novel miR-9 targets by transcriptome profiling in breast cancer cells. J Biol Chem 2012; 287:29516-28. [PMID: 22761433 DOI: 10.1074/jbc.m111.335943] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although underexpression of miR-9 in cancer cells is reported in many cancer types, it is currently difficult to classify miR-9 as a tumor suppressor or an oncomir. We demonstrate that miR-9 expression is down-regulated in MCF-7 and MDA-MB-231 breast cancer cells compared with MCF-10-2A normal breast cell line. Increasing miR-9 expression levels in breast cancer cells induced anti-proliferative, anti-invasive, and pro-apoptotic activity. In addition, microarray profiling of the transcriptome of MCF-7 cells overexpressing miR-9 identified six novel direct miR-9 targets (AP3B1, CCNG1, LARP1, MTHFD1L, MTHFD2, and SRPK1). Among these, MTHFD2 was identified as a miR-9 target gene that affects cell proliferation. Knockdown of MTHFD2 mimicked the effect observed when miR-9 was overexpressed by decreasing cell viability and increasing apoptotic activity. Despite variable effects on different cell lines, proliferative and anti-apoptotic activity of MTHFD2 was demonstrated whereby it could escape from miR-9-directed suppression (by overexpression of MTHFD2 with mutated miR-9 binding sites). Furthermore, endogenous expression levels of miR-9 and MTHFD2 displayed inverse expression profiles in primary breast tumor samples compared with normal breast samples; miR-9 was down-regulated, and MTHFD2 was up-regulated. These results indicate anti-proliferative and pro-apoptotic activity of miR-9 and that direct targeting of MTHFD2 can contribute to tumor suppressor-like activity of miR-9 in breast cancer cells.
Collapse
Affiliation(s)
- S Duygu Selcuklu
- Genetics and Biotechnology Laboratory, Centre for Chromosome Biology, National University of Ireland, Galway, Ireland
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Cheng XY, Huang WJ, Hu SC, Zhang HL, Wang H, Zhang JX, Lin HH, Chen YZ, Zou Q, Ji ZL. A global characterization and identification of multifunctional enzymes. PLoS One 2012; 7:e38979. [PMID: 22723914 PMCID: PMC3377604 DOI: 10.1371/journal.pone.0038979] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2012] [Accepted: 05/15/2012] [Indexed: 11/20/2022] Open
Abstract
Multi-functional enzymes are enzymes that perform multiple physiological functions. Characterization and identification of multi-functional enzymes are critical for communication and cooperation between different functions and pathways within a complex cellular system or between cells. In present study, we collected literature-reported 6,799 multi-functional enzymes and systematically characterized them in structural, functional, and evolutionary aspects. It was found that four physiochemical properties, that is, charge, polarizability, hydrophobicity, and solvent accessibility, are important for characterization of multi-functional enzymes. Accordingly, a combinational model of support vector machine and random forest model was constructed, based on which 6,956 potential novel multi-functional enzymes were successfully identified from the ENZYME database. Moreover, it was observed that multi-functional enzymes are non-evenly distributed in species, and that Bacteria have relatively more multi-functional enzymes than Archaebacteria and Eukaryota. Comparative analysis indicated that the multi-functional enzymes experienced a fluctuation of gene gain and loss during the evolution from S. cerevisiae to H. sapiens. Further pathway analyses indicated that a majority of multi-functional enzymes were well preserved in catalyzing several essential cellular processes, for example, metabolisms of carbohydrates, nucleotides, and amino acids. What’s more, a database of known multi-functional enzymes and a server for novel multi-functional enzyme prediction were also constructed for free access at http://bioinf.xmu.edu.cn/databases/MFEs/index.htm.
Collapse
Affiliation(s)
- Xian-Ying Cheng
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Wei-Juan Huang
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Shi-Chang Hu
- School of Information Science and Technology, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Hai-Lei Zhang
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Hao Wang
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Jing-Xian Zhang
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Hong-Huang Lin
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Yu-Zong Chen
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Quan Zou
- School of Information Science and Technology, Xiamen University, Xiamen, Fujian, People's Republic of China
- * E-mail: (QZ); (ZLJ)
| | - Zhi-Liang Ji
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
- The Key Laboratory for Chemical Biology of Fujian Province, Xiamen University, Xiamen, Fujian, People's Republic of China
- * E-mail: (QZ); (ZLJ)
| |
Collapse
|
15
|
Minguzzi S, Molloy AM, Peadar K, Mills J, Scott JM, Troendle J, Pangilinan F, Brody L, Parle-McDermott A. Genotyping of a tri-allelic polymorphism by a novel melting curve assay in MTHFD1L: an association study of nonsyndromic Cleft in Ireland. BMC MEDICAL GENETICS 2012; 13:29. [PMID: 22520921 PMCID: PMC3419639 DOI: 10.1186/1471-2350-13-29] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 04/20/2012] [Indexed: 11/18/2022]
Abstract
Background Polymorphisms within the MTHFD1L gene were previously associated with risk of neural tube defects in Ireland. We sought to test the most significant MTHFD1L polymorphisms for an association with risk of cleft in an Irish cohort. This required the development of a new melting curve assay to genotype the technically challenging MTHFD1L triallelic deletion/insertion polymorphism (rs3832406). Methods Melting curve analysis was used to genotype the MTHFD1L triallelic deletion/insertion polymorphism (rs3832406) and a Single Nucleotide Polymorphism rs17080476 in an Irish cohort consisting of 981 Irish case-parent trios and 1,008 controls. Tests for association with nonsyndromic cleft lip with or without cleft palate and cleft palate included case/control analysis, mother/control analysis and Transmission Disequilibrium Tests of case-parent trios. Results A successful melting curve genotyping assay was developed for the deletion/insertion polymorphism (rs3832406). The TDT analysis initially showed that the rs3832406 polymorphism was associated with isolated cleft lip with or without cleft palate. However, corrected p-values indicated that this association was not significant. Conclusions Melting Curve Analysis can be employed to successfully genotype challenging polymorphisms such as the MTHFD1L triallelic deletion/insertion polymorphism (DIP) reported here (rs3832406) and is a viable alternative to capillary electrophoresis. Corrected p-values indicate no association between MTHFD1L and risk of cleft in an Irish cohort.
Collapse
Affiliation(s)
- Stefano Minguzzi
- Nutritional Genomics Group, School of Biotechnology, Dublin City University, Dublin, Ireland
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
An J, Shi J, He Q, Lui K, Liu Y, Huang Y, Sheikh MS. CHCM1/CHCHD6, novel mitochondrial protein linked to regulation of mitofilin and mitochondrial cristae morphology. J Biol Chem 2012; 287:7411-26. [PMID: 22228767 DOI: 10.1074/jbc.m111.277103] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The structural integrity of mitochondrial cristae is crucial for mitochondrial functions; however, the molecular events controlling the structural integrity and biogenesis of mitochondrial cristae remain to be fully elucidated. Here, we report the functional characterization of a novel mitochondrial protein named CHCM1 (coiled coil helix cristae morphology 1)/CHCHD6. CHCM1/CHCHD6 harbors a coiled coil helix-coiled coil helix domain at its C-terminal end and predominantly localizes to mitochondrial inner membrane. CHCM1/CHCHD6 knockdown causes severe defects in mitochondrial cristae morphology. The mitochondrial cristae in CHCM1/CHCHD6-deficient cells become hollow with loss of structural definitions and reduction in electron-dense matrix. CHCM1/CHCHD6 depletion also leads to reductions in cell growth, ATP production, and oxygen consumption. CHCM1/CHCHD6 through its C-terminal end strongly and directly interacts with the mitochondrial inner membrane protein mitofilin, which is known to also control mitochondrial cristae morphology. CHCM1/CHCHD6 also interacts with other mitofilin-associated proteins, including DISC1 and CHCHD3. Knockdown of CHCM1/CHCHD6 reduces mitofilin protein levels; conversely, mitofilin knockdown leads to reduction in CHCM1 levels, suggesting coordinate regulation between these proteins. Our results further indicate that genotoxic anticancer drugs that induce DNA damage down-regulate CHCM1/CHCHD6 expression in multiple human cancer cells, whereas mitochondrial respiratory chain inhibitors do not affect CHCM1/CHCHD6 levels. CHCM1/CHCHD6 knockdown in human cancer cells enhances chemosensitivity to genotoxic anticancer drugs, whereas its overexpression increases resistance. Collectively, our results indicate that CHCM1/CHCHD6 is linked to regulation of mitochondrial cristae morphology, cell growth, ATP production, and oxygen consumption and highlight its potential as a possible target for cancer therapeutics.
Collapse
Affiliation(s)
- Jie An
- Department of Pharmacology, State University of New York, Upstate Medical University, Syracuse, New York 13210, USA
| | | | | | | | | | | | | |
Collapse
|
17
|
Ren RJ, Wang LL, Fang R, Liu LH, Wang Y, Tang HD, Deng YL, Xu W, Wang G, Chen SD. The MTHFD1L gene rs11754661 marker is associated with susceptibility to Alzheimer's disease in the Chinese Han population. J Neurol Sci 2011; 308:32-4. [DOI: 10.1016/j.jns.2011.06.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 06/20/2011] [Indexed: 12/16/2022]
|
18
|
Bolusani S, Young BA, Cole NA, Tibbetts AS, Momb J, Bryant JD, Solmonson A, Appling DR. Mammalian MTHFD2L encodes a mitochondrial methylenetetrahydrofolate dehydrogenase isozyme expressed in adult tissues. J Biol Chem 2010; 286:5166-74. [PMID: 21163947 DOI: 10.1074/jbc.m110.196840] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies in our laboratory showed that isolated, intact adult rat liver mitochondria are able to oxidize the 3-carbon of serine and the N-methyl carbon of sarcosine to formate without the addition of any other cofactors or substrates. Conversion of these 1-carbon units to formate requires several folate-interconverting enzymes in mitochondria. The enzyme(s) responsible for conversion of 5,10-methylene-tetrahydrofolate (CH(2)-THF) to 10-formyl-THF in adult mammalian mitochondria are currently unknown. A new mitochondrial CH(2)-THF dehydrogenase isozyme, encoded by the MTHFD2L gene, has now been identified. The recombinant protein exhibits robust NADP(+)-dependent CH(2)-THF dehydrogenase activity when expressed in yeast. The enzyme is localized to mitochondria when expressed in CHO cells and behaves as a peripheral membrane protein, tightly associated with the matrix side of the mitochondrial inner membrane. The MTHFD2L gene is subject to alternative splicing and is expressed in adult tissues in humans and rodents. This CH(2)-THF dehydrogenase isozyme thus fills the remaining gap in the pathway from CH(2)-THF to formate in adult mammalian mitochondria.
Collapse
Affiliation(s)
- Swetha Bolusani
- Department of Chemistry and Biochemistry and the Institute for Cellular and Molecular Biology, The University of Texas, Austin, Texas 78712, USA
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Tibbetts AS, Appling DR. Compartmentalization of Mammalian folate-mediated one-carbon metabolism. Annu Rev Nutr 2010; 30:57-81. [PMID: 20645850 DOI: 10.1146/annurev.nutr.012809.104810] [Citation(s) in RCA: 493] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The recognition that mitochondria participate in folate-mediated one-carbon metabolism grew out of pioneering work beginning in the 1950s from the laboratories of D.M. Greenberg, C.G. Mackenzie, and G. Kikuchi. These studies revealed mitochondria as the site of oxidation of one-carbon donors such as serine, glycine, sarcosine, and dimethylglycine. Subsequent work from these laboratories and others demonstrated the participation of folate coenzymes and folate-dependent enzymes in these mitochondrial processes. Biochemical and molecular genetic approaches in the 1980s and 1990s identified many of the enzymes involved and revealed an interdependence of cytoplasmic and mitochondrial one-carbon metabolism. These studies led to the development of a model of eukaryotic one-carbon metabolism that comprises parallel cytosolic and mitochondrial pathways, connected by one-carbon donors such as serine, glycine, and formate. Sequencing of the human and other mammalian genomes has facilitated identification of the enzymes that participate in this intercompartmental one-carbon metabolism, and animal models are beginning to clarify the roles of the cytoplasmic and mitochondrial isozymes of these enzymes. Identifying the mitochondrial transporters for the one-carbon donors and elucidating how flux through these pathways is controlled are two areas ripe for exploration.
Collapse
Affiliation(s)
- Anne S Tibbetts
- Department of Chemistry and Biochemistry, and the Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | | |
Collapse
|
20
|
Haynes CM, Yang Y, Blais SP, Neubert TA, Ron D. The matrix peptide exporter HAF-1 signals a mitochondrial UPR by activating the transcription factor ZC376.7 in C. elegans. Mol Cell 2010; 37:529-40. [PMID: 20188671 PMCID: PMC2846537 DOI: 10.1016/j.molcel.2010.01.015] [Citation(s) in RCA: 386] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 06/15/2009] [Accepted: 11/17/2009] [Indexed: 01/02/2023]
Abstract
Genetic analyses previously implicated the matrix-localized protease ClpP in signaling the stress of protein misfolding in the mitochondrial matrix to activate nuclear-encoded mitochondrial chaperone genes in C. elegans (UPR(mt)). Here, we report that haf-1, a gene encoding a mitochondria-localized ATP-binding cassette protein, is required for signaling within the UPR(mt) and for coping with misfolded protein stress. Peptide efflux from isolated mitochondria was ATP dependent and required HAF-1 and the protease ClpP. Defective UPR(mt) signaling in the haf-1-deleted worms was associated with failure of the bZIP protein, ZC376.7, to localize to nuclei in worms with perturbed mitochondrial protein folding, whereas zc376.7(RNAi) strongly inhibited the UPR(mt). These observations suggest a simple model whereby perturbation of the protein-folding environment in the mitochondrial matrix promotes ClpP-mediated generation of peptides whose haf-1-dependent export from the matrix contributes to UPR(mt) signaling across the mitochondrial inner membrane.
Collapse
Affiliation(s)
- Cole M. Haynes
- Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, New York 10016
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Yun Yang
- Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, New York 10016
| | - Steven P. Blais
- Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, New York 10016
| | - Thomas A. Neubert
- Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, New York 10016
- Department of Pharmacology, New York University School of Medicine, New York, New York 10016
| | - David Ron
- Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, New York 10016
- Department of Cell Biology, New York University School of Medicine, New York, New York 10016
- Department of Medicine, New York University School of Medicine, New York, New York 10016
| |
Collapse
|
21
|
Pike ST, Rajendra R, Artzt K, Appling DR. Mitochondrial C1-tetrahydrofolate synthase (MTHFD1L) supports the flow of mitochondrial one-carbon units into the methyl cycle in embryos. J Biol Chem 2009; 285:4612-20. [PMID: 19948730 DOI: 10.1074/jbc.m109.079855] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial folate-dependent one-carbon (1-C) metabolism converts 1-C donors such as serine and glycine to formate, which is exported and incorporated into the cytoplasmic tetrahydrofolate (THF) 1-C pool. Developing embryos depend on this mitochondrial pathway to provide 1-C units for cytoplasmic process such as de novo purine biosynthesis and the methyl cycle. This pathway is composed of sequential methylene-THF dehydrogenase, methenyl-THF cyclohydrolase, and 10-formyl-THF synthetase activities. In embryonic mitochondria, the bifunctional MTHFD2 enzyme catalyzes the dehydrogenase and cyclohydrolase reactions, but the enzyme responsible for the mitochondrial synthetase reaction has not been identified in embryos. A monofunctional 10-formyl-THF synthetase (MTHFD1L gene product) functions in adult mitochondria and is a likely candidate for the embryonic activity. Here we show that the MTHFD1L enzyme is present in mitochondria from normal embryonic tissues and embryonic fibroblast cell lines, and embryonic mitochondria possess the ability to synthesize formate from glycine. The MTHFD1L transcript was detected at all stages of mouse embryogenesis examined. In situ hybridizations showed that MTHFD1L was expressed ubiquitously throughout the embryo but with localized regions of higher expression. The spatial pattern of MTHFD1L expression was virtually indistinguishable from that of MTHFD2 and MTHFD1 (cytoplasmic C(1)-THF synthase) in embryonic day 9.5 mouse embryos, suggesting coordinated regulation. Finally, we show using stable isotope labeling that in an embryonic mouse cell line, greater than 75% of 1-C units entering the cytoplasmic methyl cycle are mitochondrially derived. Thus, a complete pathway of enzymes for supplying 1-C units from the mitochondria to the methyl cycle in embryonic tissues is established.
Collapse
Affiliation(s)
- Schuyler T Pike
- Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, USA
| | | | | | | |
Collapse
|
22
|
Vickers TJ, Murta SMF, Mandell MA, Beverley SM. The enzymes of the 10-formyl-tetrahydrofolate synthetic pathway are found exclusively in the cytosol of the trypanosomatid parasite Leishmania major. Mol Biochem Parasitol 2009; 166:142-52. [PMID: 19450731 DOI: 10.1016/j.molbiopara.2009.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 03/24/2009] [Accepted: 03/25/2009] [Indexed: 11/27/2022]
Abstract
In most organisms 10-formyl-tetrahydrofolate (10-CHO-THF) participates in the synthesis of purines in the cytosol and formylation of mitochondrial initiator methionyl-tRNA(Met). Here we studied 10-CHO-THF biosynthesis in the protozoan parasite Leishmania major, a purine auxotroph. Two distinct synthetic enzymes are known, a bifunctional methylene-tetrahydrofolate dehydrogenase/cyclohydrolase (DHCH) or formyl-tetrahydrofolate ligase (FTL), and phylogenomic profiling revealed considerable diversity for these in trypanosomatids. All species surveyed contain a DHCH1, which was shown recently to be essential in L. major. A second DHCH2 occurred only in L. infantum, L. mexicana and T. cruzi, and as a pseudogene in L. major. DHCH2s bear N-terminal extensions and we showed a LiDHCH2-GFP fusion was targeted to the mitochondrion. FTLs were found in all species except Trypanosoma brucei. L. major ftl(-) null mutants were phenotypically normal in growth, differentiation, animal infectivity and sensitivity to a panel of pteridine analogs, but grew more slowly when starved for serine or glycine, as expected for amino acids that are substrates in C1-folate metabolism. Cell fractionation and western blotting showed that both L. major DHCH1 and FTL were localized to the cytosol and not the mitochondrion. These localization data predict that in L. major cytosolic 10-formyl-tetrahydrofolate must be transported into the mitochondrion to support methionyl-tRNA(Met) formylation. The retention in all the trypanosomatids of at least one enzyme involved in 10-formyl-tetrahydrofolate biosynthesis, and the essentiality of this metabolite in L. major, suggests that this pathway represents a promising new area for chemotherapeutic attack in these parasites.
Collapse
Affiliation(s)
- Tim J Vickers
- Department of Molecular Microbiology, Campus Box 8230, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA
| | | | | | | |
Collapse
|