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HSPB1 Gene Variants and Schizophrenia: A Case-Control Study in a Polish Population. DISEASE MARKERS 2022; 2022:4933011. [PMID: 35340410 PMCID: PMC8941579 DOI: 10.1155/2022/4933011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 02/01/2022] [Accepted: 03/01/2022] [Indexed: 11/20/2022]
Abstract
Schizophrenia (SCZ) is a severe psychiatric disorder that has a significant genetic component. HSPB1 (HSP27) is known for its neuroprotective functions under stress conditions and appears to play an important role during the development of the central nervous system, which is in agreement with the neurodevelopmental hypothesis of SCZ. The aim of the present case-control study was to investigate whether HSPB1 variants contribute to the risk and clinical features (age of onset, symptoms, and suicidal behavior) of SCZ in a Polish population. To the best of our knowledge, this is the first study that investigated the association between the HSPB1 polymorphisms and SCZ. Three SNPs of HSPB1 (rs2868370, rs2868371, and rs7459185) were genotyped in a total of 1082 (403 patients and 679 controls) unrelated subjects using TaqMan assays. The results showed that the genotypes, alleles, and haplotypes of the three SNPs were not significantly different between the schizophrenic patients and healthy controls either in the overall analysis or in the gender-stratified analysis (all p > 0.05). However, we did find a significant effect of the rs2868371 genotype on the age of onset, negative symptoms, and disorganized symptoms in the five-factor model of PANSS (all p < 0.01). Post hoc comparisons showed that carriers of the rs2868371 G/G genotype had significantly higher negative and disorganized factor scores than those with the C/G and C/C genotypes, respectively. Further investigations with other larger independent samples are required to confirm our findings and to better explore the effect of the HSPB1 polymorphisms on the risk and symptomatology of SCZ.
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Lin WY, Chan CC, Liu YL, Yang AC, Tsai SJ, Kuo PH. Sex-specific autosomal genetic effects across 26 human complex traits. Hum Mol Genet 2021; 29:1218-1228. [PMID: 32160288 DOI: 10.1093/hmg/ddaa040] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/26/2019] [Accepted: 03/05/2020] [Indexed: 12/28/2022] Open
Abstract
Previous studies have shown that men and women have different genetic architectures across many traits. However, except waist-to-hip ratio (WHR) and waist circumference (WC), it remains unknown whether the genetic effects of a certain trait are weaker or stronger on men/women. With ~18 000 Taiwan Biobank subjects, we comprehensively investigate sexual heterogeneity in autosomal genetic effects, for traits regarding cardiovascular health, diabetes, kidney, liver, anthropometric profiles, blood, etc. 'Gene-by-sex interactions' (G $\times$ S) were detected in 18 out of 26 traits, each with an interaction P-value (${{P}}_{{INT}}$) less than $0.05/104={0.00048}$, where 104 is the number of tests conducted in this study. The most significant evidence of G $\times$ S was found in WHR (${{P}}_{{INT}}$ = 3.2 $\times{{10}}^{-{55}}$) and WC (${{P}}_{{INT}}$ = 2.3$\times{{10}}^{-{41}}$). As a novel G$\times$S investigation for other traits, we here find that the autosomal genetic effects are weaker on women than on men, for low-density lipoprotein cholesterol (LDL-C), uric acid (UA) and diabetes-related traits such as fasting glucose and glycated hemoglobin. For LDL-C and UA, the evidence of G$\times$S is especially notable in subjects aged less than 50 years, where estrogen can play a role in attenuating the autosomal genetic effects of these two traits. Men and women have systematically distinct environmental contexts caused by hormonal milieu and their specific society roles, which may trigger diverse gene expressions despite the same DNA materials. As many environmental exposures are difficult to collect and quantify, sex can serve as a good surrogate for these factors.
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Affiliation(s)
- Wan-Yu Lin
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.,Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Chang-Chuan Chan
- Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan.,Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Yu-Li Liu
- Center for Neuropsychiatric Research, National Health Research Institutes, Miaoli, Taiwan
| | - Albert C Yang
- Division of Interdisciplinary Medicine and Biotechnology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA, USA.,Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Shih-Jen Tsai
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan.,Division of Psychiatry, National Yang-Ming University, Taipei, Taiwan.,Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Po-Hsiu Kuo
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.,Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan
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Insights into S-adenosyl-l-methionine (SAM)-dependent methyltransferase related diseases and genetic polymorphisms. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2021; 788:108396. [PMID: 34893161 DOI: 10.1016/j.mrrev.2021.108396] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 10/03/2021] [Accepted: 10/05/2021] [Indexed: 12/11/2022]
Abstract
Enzymatic methylation catalyzed by methyltransferases has a significant impact on many human biochemical reactions. As the second most ubiquitous cofactor in humans, S-adenosyl-l-methionine (SAM or AdoMet) serves as a methyl donor for SAM-dependent methyltransferases (MTases), which transfer a methyl group to a nucleophilic acceptor such as O, As, N, S, or C as the byproduct. SAM-dependent methyltransferases can be grouped into different types based on the substrates. Here we systematically reviewed eight types of methyltransferases associated with human diseases. Catechol O-methyltransferase (COMT), As(III) S-adenosylmethionine methyltransferase (AS3MT), indolethylamine N-methyltransferase (INMT), phenylethanolamine N-methyltransferase (PNMT), histamine N-methyltransferase (HNMT), nicotinamide N-methyltransferase (NNMT), thiopurine S-methyltransferase (TPMT) and DNA methyltansferase (DNMT) are classic SAM-dependent MTases. Correlations between genotypes and disease susceptibility can be partially explained by genetic polymorphisms. The physiological function, substrate specificity, genetic variants and disease susceptibility associated with these eight SAM-dependent methyltransferases are discussed in this review.
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Kocinaj A, Chaudhury T, Uddin MS, Junaid RR, Ramsden DB, Hondhamuni G, Klamt F, Parsons L, Parsons RB. High Expression of Nicotinamide N-Methyltransferase in Patients with Sporadic Alzheimer's Disease. Mol Neurobiol 2021; 58:1769-1781. [PMID: 33387303 PMCID: PMC7932959 DOI: 10.1007/s12035-020-02259-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 12/10/2020] [Indexed: 01/11/2023]
Abstract
We have previously shown that the expression of nicotinamide N-methyltransferase (NNMT) is significantly increased in the brains of patients who have died of Parkinson's disease (PD). In this study, we have compared the expression of NNMT in post-mortem medial temporal lobe, hippocampus and cerebellum of 10 Alzheimer's disease (AD) and 9 non-disease control subjects using a combination of quantitative Western blotting, immunohistochemistry and dual-label confocal microscopy coupled with quantitative analysis of colocalisation. NNMT was detected as a single protein of 29 kDa in both AD and non-disease control brains, which was significantly increased in AD medial temporal lobe compared to non-disease controls (7.5-fold, P < 0.026). There was no significant difference in expression in the cerebellum (P = 0.91). NNMT expression in AD medial temporal lobe and hippocampus was present in cholinergic neurones with no glial localisation. Cell-type expression was identical in both non-disease control and AD tissues. These results are the first to show, in a proof-of-concept study using a small patient cohort, that NNMT protein expression is increased in the AD brain and is present in neurones which degenerate in AD. These results suggest that the elevation of NNMT may be a common feature of many neurodegenerative diseases. Confirmation of this overexpression using a larger AD patient cohort will drive the future development of NNMT-targetting therapeutics which may slow or stop the disease pathogenesis, in contrast to current therapies which solely address AD symptoms.
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Affiliation(s)
- Altin Kocinaj
- Institute of Pharmaceutical Science, King’s College London, 150 Stamford Street, London, SE1 9NH UK
| | - Tabassum Chaudhury
- Institute of Pharmaceutical Science, King’s College London, 150 Stamford Street, London, SE1 9NH UK
| | - Mohammed S. Uddin
- Institute of Pharmaceutical Science, King’s College London, 150 Stamford Street, London, SE1 9NH UK
| | - Rashad R. Junaid
- Institute of Pharmaceutical Science, King’s College London, 150 Stamford Street, London, SE1 9NH UK
| | - David B. Ramsden
- Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, Birmingham, B15 2TH UK
| | - Geshanthi Hondhamuni
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London, WC1N 1PJ UK
| | - Fábio Klamt
- Laboratory of Cellular Biochemistry, Universidade Federal do Rio Grande do Sul, 2600 Ramiro Barcelos St., Porto Alegre, RS 90035-003 Brazil
- National Institute of Science and Technology – Translational Medicine (INCT-TM), Porto Alegre, Brazil
| | - Linda Parsons
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, University College London, 1 Wakefield Street, London, WC1N 1PJ UK
| | - Richard B. Parsons
- Institute of Pharmaceutical Science, King’s College London, 150 Stamford Street, London, SE1 9NH UK
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Ramsden DB, Waring RH, Parsons RB, Barlow DJ, Williams AC. Nicotinamide N-Methyltransferase: Genomic Connection to Disease. Int J Tryptophan Res 2020; 13:1178646920919770. [PMID: 32547055 PMCID: PMC7273554 DOI: 10.1177/1178646920919770] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Accepted: 03/24/2020] [Indexed: 12/20/2022] Open
Abstract
Single-nucleotide polymorphisms (SNPs) in and around the nicotinamide
N-methyltransferase (NNMT) gene are associated with a range
of cancers and other diseases and conditions. The data on these associations
have been assembled, and their strength discussed. There is no evidence that the
presence of either the major or minor base in any SNP affects the expression of
nicotinamide N-methyltransferase. Nevertheless, suggestions
have been put forward that some of these SNPs do affect NNMT expression and thus
homocysteine metabolism. An alternative idea involving non-coding messenger RNAs
(mRNAs) is suggested as a possible mechanism whereby health is influenced. It is
postulated that these long, non-coding NNMT mRNAs may exert deleterious effects
by interfering with the expression of other genes. Neither hypothesis, however,
has experimental proof, and further work is necessary to elucidate NNMT genetic
interactions.
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Affiliation(s)
- David B Ramsden
- Institute of Metabolism and Systems Research, The Medical School, University of Birmingham, Birmingham, UK
| | | | - Richard B Parsons
- Institute of Pharmaceutical Science, Kings College London, London, UK
| | - David J Barlow
- Institute of Pharmaceutical Science, Kings College London, London, UK
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Hu Q, Liu F, Yang L, Fang Z, He J, Wang W, You P. Lower serum nicotinamide N-methyltransferase levels in patients with bipolar disorder during acute episodes compared to healthy controls: a cross-sectional study. BMC Psychiatry 2020; 20:33. [PMID: 32000734 PMCID: PMC6990555 DOI: 10.1186/s12888-020-2461-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 01/23/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Nicotinamide N-methyltransferase (NNMT) has been implicated in the pathogenesis of neuropsychiatric diseases. Bipolar disorder (BD) is associated with metabolic abnormalities and NNMT regulates energy metabolism and may also exert a causal role in metabolic disorders. The present study aimed to determine serum NNMT levels in patients with BD and compared the results with that of healthy controls, to explore the correlation between NNMT and clinical and metabolic characteristics. METHODS The NNMT levels of 80 patients having a manic episode of BD and 65 non-psychiatric control individuals were measured using enzyme-linked immunosorbent assay. Metabolic parameters were evaluated using standard laboratory methods. RESULTS The serum NNMT levels of bipolar mania patients were significantly lower than that of non-psychiatric controls. Furthermore, the serum levels of NNMT were found to be negatively correlated with Young Mania Rating Scale (YMRS) scores and the duration of the illness. Moreover, lower NNMT serum levels were found in patients with a history of antipsychotic medication and dyslipidemia. Our results also demonstrated the different patterns of correlation that exist between the study groups. Serum NNMT levels were found to be negatively correlated with triglyceride, cholesterol, and apolipoprotein B levels in the BD group, while the same was found to be negatively associated only with high-density lipoprotein cholesterol in the control group. CONCLUSIONS These findings support the suggestion that lower NNMT serum levels are significantly associated with BD and that serum NNMT has the potential to regulate lipid metabolism in BD patients.
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Affiliation(s)
- Qing Hu
- Xiamen Xianyue Hospital, 399# Xianyue Road, Xiamen, 361012 China
| | - Farong Liu
- Xiamen Xianyue Hospital, 399# Xianyue Road, Xiamen, 361012 China ,grid.412625.6The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Luyin Yang
- 0000 0001 2264 7233grid.12955.3aArts College of Xiamen University, Xiamen, China
| | - Zanxi Fang
- 0000 0001 2264 7233grid.12955.3aZhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
| | - Jue He
- Xiamen Xianyue Hospital, 399# Xianyue Road, Xiamen, 361012 China
| | - Wenqiang Wang
- Xiamen Xianyue Hospital, 399# Xianyue Road, Xiamen, 361012 China
| | - Pan You
- Xiamen Xianyue Hospital, 399# Xianyue Road, Xiamen, 361012, China.
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Schmeisser K, Parker JA. Nicotinamide-N-methyltransferase controls behavior, neurodegeneration and lifespan by regulating neuronal autophagy. PLoS Genet 2018; 14:e1007561. [PMID: 30192747 PMCID: PMC6191153 DOI: 10.1371/journal.pgen.1007561] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 10/16/2018] [Accepted: 07/09/2018] [Indexed: 12/14/2022] Open
Abstract
Nicotinamide N-methyl-transferase (NNMT) is an essential contributor to various metabolic and epigenetic processes, including the regulating of aging, cellular stress response, and body weight gain. Epidemiological studies show that NNMT is a risk factor for psychiatric diseases like schizophrenia and neurodegeneration, especially Parkinson's disease (PD), but its neuronal mechanisms of action remain obscure. Here, we describe the role of neuronal NNMT using C. elegans. We discovered that ANMT-1, the nematode NNMT ortholog, competes with the methyltransferase LCMT-1 for methyl groups from S-adenosyl methionine. Thereby, it regulates the catalytic capacities of LCMT-1, targeting NPRL-2, a regulator of autophagy. Autophagy is a core cellular, catabolic process for degrading cytoplasmic material, but very little is known about the regulation of autophagy during aging. We report an important role for NNMT in regulation of autophagy during aging, where high neuronal ANMT-1 activity induces autophagy via NPRL-2, which maintains neuronal function in old wild type animals and various disease models, also affecting longevity. In younger animals, however, ANMT-1 activity disturbs neuronal homeostasis and dopamine signaling, causing abnormal behavior. In summary, we provide fundamental insights into neuronal NNMT/ANMT-1 as pivotal regulator of behavior, neurodegeneration, and lifespan by controlling neuronal autophagy, potentially influencing PD and schizophrenia risk in humans.
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Affiliation(s)
- Kathrin Schmeisser
- Research Center of the Centre Hospitalier de l‘Université de Montréal (CRCHUM), Department of Neuroscience, Université de Montréal, Quebec, Canada
| | - J. Alex Parker
- Research Center of the Centre Hospitalier de l‘Université de Montréal (CRCHUM), Department of Neuroscience, Université de Montréal, Quebec, Canada
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Integrating genome-wide association study and expression quantitative trait locus study identifies multiple genes and gene sets associated with schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2018; 81:50-54. [PMID: 29024729 DOI: 10.1016/j.pnpbp.2017.10.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 09/25/2017] [Accepted: 10/04/2017] [Indexed: 02/02/2023]
Abstract
Schizophrenia is a serious mental disease with high heritability. To better understand the genetic basis of schizophrenia, we conducted a large scale integrative analysis of genome-wide association study (GWAS) and expression quantitative trait loci (eQTLs) data. GWAS summary data was derived from a published GWAS of schizophrenia, containing 9394 schizophrenia patients and 12,462 healthy controls. The eQTLs dataset was obtained from an eQTLs meta-analysis of 5311 subjects, containing 923,021 cis-eQTLs for 14,329 genes and 4732 trans-eQTLs for 2612 genes. Genome-wide single gene expression association analysis was conducted by SMR software. The SMR analysis results were further subjected to gene set enrichment analysis (GSEA) to identify schizophrenia associated gene sets. SMR detected 49 genes significantly associated with schizophrenia. The top five significant genes were CRELD2 (p value=1.65×10-11), DIP2B (p value=3.94×10-11), ZDHHC18 (p value=1.52×10-10) and ZDHHC5 (p value=7.45×10-10), C11ORF75 (p value=3.70×10-9). GSEA identified 80 gene sets with p values <0.01. The top five significant gene sets were COWLING_MYCN_TARGETS (p value <0.001) and CHR16P11 (p value <0.001), ACTACCT_MIR196A_MIR196B (p value=0.002), CELLULAR_COMPONENT_DISASSEMBLY (p value=0.002) and GRAESSMANN_RESPONSE_TO_MC_AND_DOXORUBICIN_DN (p value=0.002). Our results provide useful information for revealing the genetic basis of schizophrenia.
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Role of Nicotinamide N-Methyltransferase in Dorsal Striatum in Cocaine Place Preference. Neuropsychopharmacology 2017; 42:2333-2343. [PMID: 28726800 PMCID: PMC5645739 DOI: 10.1038/npp.2017.147] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 07/09/2017] [Accepted: 07/13/2017] [Indexed: 02/05/2023]
Abstract
Nicotinamide N-methyltransferase (NNMT) transfers the methyl from S-adenosyl-L-methionine (SAM) to nicotinamide (NA) to produce S-adenosyl-L-homocysteine (SAH) and 1-methylnicotinamide (MeN). NNMT has been implicated in a variety of diseases; however, the role of NNMT in drug addiction is largely unknown. Here, we found that the expression of Nnmt was significantly upregulated in the dorsal striatum (DS) of cocaine-conditioned mice. Cocaine significantly decreased SAM/SAH ratio levels in the DS, which was accompanied with the decreased activities of Rac1 and RhoA. Lentivirus-mediated knockdown of Nnmt in the dorsomedial striatum (DMS) attenuated cocaine conditioned place preference (CPP) reward, but increased striatal SAM/SAH ratio levels as well as Rac1 and RhoA activities. In addition, pharmacological inhibition of NNMT through intra-DMS infusion of MeN attenuated cocaine CPP and the activities of Rac1 and RhoA, but increased SAM/SAH ratio. These results suggest that NNMT-dependent transmethylation is involved in the activation of Rac1 and RhoA, which utilize SAM as a methyl donor cofactor. Co-immunoprecipitation assay using a RhoGDIα antibody indirectly captured Rac1 or RhoA that were bound to RhoGDIα. The results showed that cocaine increased the association of RhoGDIα with Rac1 or RhoA, whereas such effect was inhibited by Nnmt knockdown. Collectively, our findings show that NNMT regulates cocaine CPP through SAM-mediated modification of Rac1 and RhoA.
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Pissios P. Nicotinamide N-Methyltransferase: More Than a Vitamin B3 Clearance Enzyme. Trends Endocrinol Metab 2017; 28:340-353. [PMID: 28291578 PMCID: PMC5446048 DOI: 10.1016/j.tem.2017.02.004] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 02/01/2017] [Accepted: 02/02/2017] [Indexed: 12/18/2022]
Abstract
Nicotinamide (NAM) N-methyltransferase (NNMT) was originally identified as the enzyme responsible for the methylation of NAM, one of the forms of vitamin B3. Methylated NAM is eventually excreted from the body. Recent evidence has expanded the role of NNMT beyond clearance of excess vitamin B3. NNMT has been implicated in the regulation of multiple metabolic pathways in tissues such as adipose and liver as well as cancer cells through the consumption of methyl donors and generation of active metabolites. This review examines recent findings regarding the function of NNMT in physiology and disease and highlights potential new avenues for therapeutic intervention. Finally, key gaps in our knowledge about this enzymatic system and future areas of investigation are discussed.
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Affiliation(s)
- Pavlos Pissios
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
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Badawy AAB. Kynurenine Pathway of Tryptophan Metabolism: Regulatory and Functional Aspects. Int J Tryptophan Res 2017; 10:1178646917691938. [PMID: 28469468 PMCID: PMC5398323 DOI: 10.1177/1178646917691938] [Citation(s) in RCA: 633] [Impact Index Per Article: 90.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 01/11/2017] [Indexed: 12/21/2022] Open
Abstract
Regulatory and functional aspects of the kynurenine (K) pathway (KP) of tryptophan (Trp) degradation are reviewed. The KP accounts for ~95% of dietary Trp degradation, of which 90% is attributed to the hepatic KP. During immune activation, the minor extrahepatic KP plays a more active role. The KP is rate-limited by its first enzyme, Trp 2,3-dioxygenase (TDO), in liver and indoleamine 2,3-dioxygenase (IDO) elsewhere. TDO is regulated by glucocorticoid induction, substrate activation and stabilization by Trp, cofactor activation by heme, and end-product inhibition by reduced nicotinamide adenine dinucleotide (phosphate). IDO is regulated by IFN-γ and other cytokines and by nitric oxide. The KP disposes of excess Trp, controls hepatic heme synthesis and Trp availability for cerebral serotonin synthesis, and produces immunoregulatory and neuroactive metabolites, the B3 “vitamin” nicotinic acid, and oxidized nicotinamide adenine dinucleotide. Various KP enzymes are undermined in disease and are targeted for therapy of conditions ranging from immunological, neurological, and neurodegenerative conditions to cancer.
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Affiliation(s)
- Abdulla A-B Badawy
- Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK
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Abstract
Here, we report the association of the rs694539 variant of nicotinamide-N-methyltransferase gene with epilepsy in a case-control study of 215 patients with epilepsy and 239 healthy controls (χ (2) = 11.641, P = 0.003). The individuals with the GG genotype revealed protection against epilepsy (χ (2) = 5.866, P = 0.015, OR = 0.623, 95 % CI = 0.425-0.915), whereas the individuals with the AA genotype showed statistically significant increased risk for epilepsy (χ (2) = 8.676, P = 0.003, OR = 5.479, 95 % CI = 1.553-19.337). In addition, the G allele was protective against epilepsy (χ (2) = 8.676, P = 0.003, OR = 0.183, 95 % CI = 0.052-0.644); on the contrary, the A allele was a genetic risk factor for epilepsy (χ (2) = 5.866, P = 0.015, OR = 1.604, 95 % CI = 1.093-2.354). Stratification analysis revealed that the association was statistically significant in male patients with epilepsy (χ (2) = 6.682, P = 0.035). However, the statistical power was only 0.33 in female patients with epilepsy (χ (2) = 5.275, P = 0.072). This finding, for the first time, suggests the involvement of the NNMT gene rs694539 variant in the etiology of epilepsy.
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