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Kuo KL, Chiang CW, Chen YMA, Yu CC, Lee TS. Folic Acid Ameliorates Renal Injury in Experimental Obstructive Nephropathy: Role of Glycine N-Methyltransferase. Int J Mol Sci 2023; 24:ijms24076859. [PMID: 37047834 PMCID: PMC10095475 DOI: 10.3390/ijms24076859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/31/2023] [Accepted: 04/04/2023] [Indexed: 04/14/2023] Open
Abstract
Folic acid exerts both anti-inflammatory and antifibrotic effects. Glycine N-methyltransferase (GNMT), the major folic acid-binding protein in the liver, is a crucial enzyme that regulates the cellular methylation process by maintaining S-adenosylmethionine levels. However, as yet neither the therapeutic effects of folic acid in renal fibrosis nor whether GNMT is involved in these folic acid-associated mechanisms has been investigated. First, the expression of GNMT was examined in human kidneys with or without obstructive nephropathy. Later, wild-type and GNMT knockout (GNMT-/-) mice were subjected to unilateral ureteral obstruction (UUO) and then treated with either folic acid or vehicle for 14 days. Renal tubular injury, inflammation, fibrosis, and autophagy were evaluated by histological analysis and Western blotting. We observed increased expression of GNMT in humans with obstructive nephropathy. Furthermore, UUO significantly increased the expression of GNMT in mice; in addition, it caused renal injury as well as the development of both hydronephrosis and tubular injury. These were all alleviated by folic acid treatment. In contrast, GNMT-/- mice exhibited exacerbated UUO-induced renal injury, but the protective effect of folic acid was not observed in GNMT-/- mice. We propose a novel role for folic acid in the treatment of renal fibrosis, which indicates that GNMT may be a therapeutic target.
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Affiliation(s)
- Ko-Lin Kuo
- Division of Nephrology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 231405, Taiwan
- School of Medicine, Buddhist Tzu Chi University, Hualien 97004, Taiwan
- School of Post-Baccalaureate Chinese Medicine, Tzu Chi University, Hualien 97004, Taiwan
| | - Chin-Wei Chiang
- Department of Physiology, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
| | - Yi-Ming Arthur Chen
- Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei 24205, Taiwan
| | - Chih-Chin Yu
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 231405, Taiwan
- College of Medicine, Tzu Chi University, Hualien 97004, Taiwan
| | - Tzong-Shyuan Lee
- Graduate Institute, Department of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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Yang MH, Li WY, Wu CF, Lee YC, Chen AYN, Tyan YC, Chen YMA. Reversal of High-Fat Diet-Induced Non-Alcoholic Fatty Liver Disease by Metformin Combined with PGG, an Inducer of Glycine N-Methyltransferase. Int J Mol Sci 2022; 23:ijms231710072. [PMID: 36077467 PMCID: PMC9456083 DOI: 10.3390/ijms231710072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/27/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a major cause of liver-related morbidities and mortality, and no effective drug treatment currently exists. We aimed to develop a novel treatment strategy to induce the expression of glycine N-methyltransferase (GNMT), which is an important enzyme regulating S-adenosylmethionine metabolism whose expression is downregulated in patients with NAFLD. Because 1,2,3,4,6-pentagalloyl glucose (PGG) is a GNMT inducer, and metformin was shown to upregulate liver mitochondrial GNMT protein expression, the effect of PGG and metformin was evaluated. Biochemical analysis, histopathological examination, immunohistochemical staining, reverse transcription-quantitative PCR (RT-qPCR), Western blotting (WB), proteomic analysis and Seahorse XF Cell Mito Stress Test were performed. The high-fat diet (HFD)-induced NAFLD mice were treated with PGG and metformin. Combination of PGG and metformin nearly completely reversed weight gain, elevation of serum aminotransferases, and hepatic steatosis and steatohepatitis. In addition, the downregulated GNMT expression in liver tissues of HFD-induced NAFLD mice was restored. The GNMT expression was further confirmed by RT-qPCR and WB analysis using both in vitro and in vivo systems. In addition, PGG treatment was shown to increase oxygen consumption rate (OCR) maximum capacity in a dose-dependent manner, and was capable of rescuing the suppression of mitochondrial OCR induced by metformin. Proteomic analysis identified increased expression of glutathione S-transferase mu 4 (GSTM4), heat shock protein 72 (HSP72), pyruvate carboxylase (PYC) and 40S ribosomal protein S28 (RS28) in the metformin plus PGG treatment group. Our findings show that GNMT expression plays an important role in the pathogenesis of NAFLD, and combination of an inducer of GNMT and metformin can be of therapeutic potential for patients with NAFLD.
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Affiliation(s)
- Ming-Hui Yang
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan
- Center of General Education, Shu-Zen Junior College of Medicine and Management, Kaohsiung 821, Taiwan
| | - Wei-You Li
- Laboratory of Important Infectious Diseases and Cancer, Graduate Institute of Biomedical and Pharmacological Science, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan
| | - Ching-Fen Wu
- Department of Veterinary Medicine, National Chiayi University, Chiayi City 600, Taiwan
| | - Yi-Ching Lee
- Laboratory of Important Infectious Diseases and Cancer, Graduate Institute of Biomedical and Pharmacological Science, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan
| | - Allan Yi-Nan Chen
- School of Medicine, University of California, Davis, Sacramento, CA 95817, USA
| | - Yu-Chang Tyan
- Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Department of Nuclear Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
- Graduate Institute of Animal Vaccine Technology, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 912, Taiwan
- School of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
- Center for Cancer Research, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Research Center for Precision Environmental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung 804, Taiwan
- Correspondence: (Y.-C.T.); (Y.-M.A.C.)
| | - Yi-Ming Arthur Chen
- Laboratory of Important Infectious Diseases and Cancer, Graduate Institute of Biomedical and Pharmacological Science, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli County 350, Taiwan
- Correspondence: (Y.-C.T.); (Y.-M.A.C.)
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Lu J, Weil JT, Cerrate S, Coon CN. Ontogeny of hepatic methionine catabolic enzyme activities (Transmethylation and Transsulphuration) and associated physiological amino acids in E10-21 chick embryos and D1-49 broilers. J Anim Physiol Anim Nutr (Berl) 2020; 105:507-519. [PMID: 33159699 DOI: 10.1111/jpn.13463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 07/29/2020] [Accepted: 09/09/2020] [Indexed: 01/25/2023]
Abstract
Developmental changes in hepatic methionine adenosyltransferase, cystathionine β-synthase, cystathionase, and glycine N-methyltransferase were determined in broiler chick embryos and hatched chicks by using radiometric and spectrometric methods. Hepatic free methionine, S-adenosylmethionine, S-adenosylhomocysteine, homocysteine, cystathionine, and cysteine levels were also investigated. Results showed an increase in hepatic MAT activity from E10 to E21 during embryogenesis, suggesting greater transmethylation rates throughout the rapid embryonic growth and development period. A strong positive correlation between embryo BW and MAT activity also supports this idea. The MAT specific activity continued to increase after hatching, but there was a negative correlation between chick BW and MAT activities from D1 to D49. This may indicate different MAT isozymes exist for chick embryo hepatic tissue compared to hepatic tissue of hatched chick and growing broilers. The developmental pattern of MAT isozymes could be critical for methionine metabolism to cope with the demand imposed on the embryo, chicks, and growing broilers. Additionally, the specific activity of hepatic CBS in chick embryos was determined to be lower compared to that observed in older broilers (35 and 49 days). Since liver CBS specific activity is at the lowest point from D1-7 in young chicks, the ability to convert adequate homocysteine to cysteine through transsulphuration may be limiting for cysteine synthesis at this time. Steady-state hepatic homocysteine levels in chick embryos and chicks may be a function of the rates of homocysteine formation, remethylation, and catabolism via the transsulphuration pathway. The present study indicates young chicks from D1 to D7 may have a limited ability for adequate transsulphuration; therefore, dietary cystine may be needed for optimum performance.
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Affiliation(s)
| | - Jordan Taylor Weil
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, USA
| | | | - Craig Nelson Coon
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, USA
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Stipanuk MH. Metabolism of Sulfur-Containing Amino Acids: How the Body Copes with Excess Methionine, Cysteine, and Sulfide. J Nutr 2020; 150:2494S-2505S. [PMID: 33000151 DOI: 10.1093/jn/nxaa094] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/28/2020] [Accepted: 03/16/2020] [Indexed: 02/06/2023] Open
Abstract
Metabolism of excess methionine (Met) to homocysteine (Hcy) by transmethylation is facilitated by the expression of methionine adenosyltransferase (MAT) I/III and glycine N-methyltransferase (GNMT) in liver, and a lack of either enzyme results in hypermethioninemia despite normal concentrations of MATII and methyltransferases other than GNMT. The further metabolism of Hcy by the transsulfuration pathway is facilitated by activation of cystathionine β-synthase (CBS) by S-adenosylmethionine (SAM) as well as the relatively high KM of CBS for Hcy. Transmethylation plus transsulfuration effects catabolism of the Met molecule along with transfer of the sulfur atom of Met to serine to synthesize cysteine (Cys). Oxidation and excretion of Met sulfur depend upon Cys catabolism and sulfur oxidation pathways. Excess Cys is oxidized by cysteine dioxygenase 1 (CDO1) and further metabolized to taurine or sulfate. Some Cys is normally metabolized by desulfhydration pathways, and the hydrogen sulfide (H2S) produced is further oxidized to sulfate. If Cys or Hcy concentrations are elevated, Cys or Hcy desulfhydration can result in excess H2S and thiosulfate production. Excess Cys or Met may also promote their limited metabolism by transamination pathways.
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Affiliation(s)
- Martha H Stipanuk
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA
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Kitada M, Ogura Y, Monno I, Xu J, Koya D. Methionine abrogates the renoprotective effect of a low-protein diet against diabetic kidney disease in obese rats with type 2 diabetes. Aging (Albany NY) 2020; 12:4489-4505. [PMID: 32145700 PMCID: PMC7093197 DOI: 10.18632/aging.102902] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 01/27/2020] [Indexed: 06/10/2023]
Abstract
Dietary interventions, including a low-protein diet (LPD) and methionine (Met) restriction, have shown longevity, anti-aging and metabolic health effects. We previously reported that the LPD has a renoprotective effect against diabetic kidney disease (DKD) in rats with type 2 diabetes and obesity. However, it is unclear whether the beneficial effect of the LPD is mediated by low-Met intake or how Met is related to the pathogenesis for DKD. We herein show that the addition of Met with the LPD abrogates the beneficial effects induced by the LPD such as anti-oxidative stress, anti-inflammation and anti-fibrosis, in diabetic kidney. Additionally, the increased levels of S-adenosylmethionine (SAM) in renal tubular cells, which are associated with the reduced expression of glycine N-methyltransferase (Gnmt) and non-restricted Met intake, contributes to the activation of mechanistic target of rapamycin complex 1 (mTORC1) and impaired autophagy, in diabetic kidney. Moreover, starvation-induced autophagy was suppressed in renal cortex of Gnmt null mice and amino acid free-induced autophagy was also suppressed by administration of SAM in cultured HK-2 cells. A LPD could exert a renoprotective effect through the suppression of mTORC1 and restoration of autophagy, which is associated with reduced levels of SAM due to low-Met intake, in diabetic kidney.
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Affiliation(s)
- Munehiro Kitada
- Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan
- Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Yoshio Ogura
- Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Itaru Monno
- Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Jing Xu
- Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Daisuke Koya
- Department of Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa, Japan
- Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa, Japan
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Huang JW, Chen CJ, Yen CH, Chen YMA, Liu YP. Loss of Glycine N-Methyltransferase Associates with Angiopoietin-Like Protein 8 Expression in High Fat-Diet-Fed Mice. Int J Mol Sci 2019; 20:ijms20174223. [PMID: 31470507 PMCID: PMC6747252 DOI: 10.3390/ijms20174223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 08/27/2019] [Accepted: 08/27/2019] [Indexed: 12/16/2022] Open
Abstract
Imbalance of lipid metabolism is a main cause of metabolic syndrome leading to life-threatening metabolic diseases. Angiopoietin-like protein 8 (Angptl8) was recently identified as a liver and adipose tissue-released hormone that is one of the molecules involved in triglyceride metabolism. However, the regulatory mechanism of Angptl8 is largely unknown. A high fat diet (HFD)-fed mouse model, which showed high cholesterol, high triglyceride, and high insulin in the blood, revealed the upregulation of hepatic and plasma Angptl8 and the downregulation of hepatic glycine N-methyltransferase (GNMT). The inverse correlation of hepatic Angptl8 and GNMT expression in the livers of HFD-fed mice was also confirmed in a publicly available microarray dataset. The mechanistic study using primary hepatocytes showed that the Angptl8 expression could be induced by insulin treatment in a dose- and time-dependent manner. Inhibition of PI3K/Akt pathway by the specific inhibitors or the dominant-negative Akt blocked the insulin-induced Angptl8 expression. Moreover, knockout of GNMT promoted the Akt activation as well as the Angptl8 expression. These results suggested that GNMT might be involved in insulin-induced Angptl8 expression in HFD-mediated metabolic syndrome.
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Affiliation(s)
- Jian-Wei Huang
- Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Division of General Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Chao-Ju Chen
- Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Chia-Hung Yen
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Yi-Ming Arthur Chen
- Master Program of Clinical Pharmacogenomics and Pharmacoproteomics, College of Pharmacy, Taipei Medical University, Taipei 11031, Taiwan
| | - Yu-Peng Liu
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
- Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
- Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
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7
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Yang MH, Chen WJ, Fu YS, Huang B, Tsai WC, Arthur Chen YM, Lin PC, Yuan CH, Tyan YC. Utilizing glycine N-methyltransferasegene knockout mice as a model for identification of missing proteins in hepatocellular carcinoma. Oncotarget 2017; 9:442-452. [PMID: 29416626 PMCID: PMC5787479 DOI: 10.18632/oncotarget.23064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 11/13/2017] [Indexed: 11/25/2022] Open
Abstract
Glycine N-methyltransferase is a tumor suppressor gene for hepatocellular carcinoma, which can activate DNA methylation by inducing the S-adenosylmethionine to S-adenosylhomocystine. Previous studies have indicated that the expression of Glycine N-methyltransferase is inhibited in hepatocellular carcinoma. To confirm and identify missing proteins, the pathologic analysis of the tumor-bearing mice will provide critical histologic information. Such a mouse model is applied as a screening tool for hepatocellular carcinoma as well as a strategy for missing protein discovery. In this study we designed an analysis platform using the human proteome atlas to compare the possible missing proteins to human whole chromosomes. This will integrate the information from animal studies to establish an optimal technique in the missing protein biomarker discovery.
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Affiliation(s)
- Ming-Hui Yang
- Center for Infectious Disease and Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Wan-Jou Chen
- Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yaw-Syan Fu
- Center for Infectious Disease and Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Bin Huang
- Center for Infectious Disease and Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Wan-Chi Tsai
- Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yi-Ming Arthur Chen
- Center for Infectious Disease and Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan.,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Po-Chiao Lin
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Cheng-Hui Yuan
- Mass Spectrometry Laboratory, Department of Chemistry, National University of Singapore, Singapore
| | - Yu-Chang Tyan
- Center for Infectious Disease and Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan.,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung, Taiwan.,Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
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8
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Carrasco M, Rabaneda LG, Murillo-Carretero M, Ortega-Martínez S, Martínez-Chantar ML, Woodhoo A, Luka Z, Wagner C, Lu SC, Mato JM, Micó JA, Castro C. Glycine N-methyltransferase expression in the hippocampus and its role in neurogenesis and cognitive performance. Hippocampus 2014; 24:840-52. [PMID: 24687756 DOI: 10.1002/hipo.22274] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2014] [Indexed: 01/23/2023]
Abstract
The hippocampus is a brain area characterized by its high plasticity, observed at all levels of organization: molecular, synaptic, and cellular, the latter referring to the capacity of neural precursors within the hippocampus to give rise to new neurons throughout life. Recent findings suggest that promoter methylation is a plastic process subjected to regulation, and this plasticity seems to be particularly important for hippocampal neurogenesis. We have detected the enzyme GNMT (a liver metabolic enzyme) in the hippocampus. GNMT regulates intracellular levels of SAMe, which is a universal methyl donor implied in almost all methylation reactions and, thus, of prime importance for DNA methylation. In addition, we show that deficiency of this enzyme in mice (Gnmt-/-) results in high SAMe levels within the hippocampus, reduced neurogenic capacity, and spatial learning and memory impairment. In vitro, SAMe inhibited neural precursor cell division in a concentration-dependent manner, but only when proliferation signals were triggered by bFGF. Indeed, SAMe inhibited the bFGF-stimulated MAP kinase signaling cascade, resulting in decreased cyclin E expression. These results suggest that alterations in the concentration of SAMe impair neurogenesis and contribute to cognitive decline.
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Affiliation(s)
- Manuel Carrasco
- Area de Fisiologia, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain
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Abstract
The development and growth of prostate cancer is dependent on androgens; thus, the identification of androgen-regulated genes in prostate cancer cells is vital for defining the mechanisms of prostate cancer development and progression and developing new markers and targets for prostate cancer treatment. Glycine N-methyltransferase (GNMT) is a S-adenosylmethionine-dependent methyltransferase that has been recently identified as a novel androgen-regulated gene in prostate cancer cells. Although the importance of this protein in prostate cancer progression has been extensively addressed, little is known about the mechanism of its androgen regulation. Here, we show that GNMT expression is stimulated by androgen in androgen receptor (AR) expressing cells and that the stimulation occurs at the mRNA and protein levels. We have identified an androgen response element within the first exon of the GNMT gene and demonstrated that AR binds to this element in vitro and in vivo. Together, these studies identify GNMT as a direct transcriptional target of the AR. As this is an evolutionarily conserved regulatory element, this highlights androgen regulation as an important feature of GNMT regulation.
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Affiliation(s)
| | - Greg N Brooke
- School of Biological SciencesUniversity of EssexColchesterUK
| | | | | | - Simak Ali
- Correspondence should be addressed to L Buluwela or S Ali, or
| | - Laki Buluwela
- Correspondence should be addressed to L Buluwela or S Ali, or
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10
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Frau M, Feo F, Pascale RM. Pleiotropic effects of methionine adenosyltransferases deregulation as determinants of liver cancer progression and prognosis. J Hepatol 2013; 59:830-41. [PMID: 23665184 DOI: 10.1016/j.jhep.2013.04.031] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 04/15/2013] [Accepted: 04/23/2013] [Indexed: 12/13/2022]
Abstract
Downregulation of liver-specific MAT1A gene, encoding S-adenosylmethionine (SAM) synthesizing isozymes MATI/III, and upregulation of widely expressed MAT2A, encoding MATII isozyme, known as MAT1A:MAT2A switch, occurs in hepatocellular carcinoma (HCC). Being inhibited by its reaction product, MATII isoform upregulation cannot compensate for MATI/III decrease. Therefore, MAT1A:MAT2A switch contributes to decrease in SAM level in rodent and human hepatocarcinogenesis. SAM administration to carcinogen-treated rats prevents hepatocarcinogenesis, whereas MAT1A-KO mice, characterized by chronic SAM deficiency, exhibit macrovesicular steatosis, mononuclear cell infiltration in periportal areas, and HCC development. This review focuses upon the pleiotropic changes, induced by MAT1A/MAT2A switch, associated with HCC development. Epigenetic control of MATs expression occurs at transcriptional and post-transcriptional levels. In HCC cells, MAT1A/MAT2A switch is associated with global DNA hypomethylation, decrease in DNA repair, genomic instability, and signaling deregulation including c-MYC overexpression, rise in polyamine synthesis, upregulation of RAS/ERK, IKK/NF-kB, PI3K/AKT, and LKB1/AMPK axis. Furthermore, decrease in MAT1A expression and SAM levels results in increased HCC cell proliferation, cell survival, and microvascularization. All of these changes are reversed by SAM treatment in vivo or forced MAT1A overexpression or MAT2A inhibition in cultured HCC cells. In human HCC, MAT1A:MAT2A and MATI/III:MATII ratios correlate negatively with cell proliferation and genomic instability, and positively with apoptosis and global DNA methylation. This suggests that SAM decrease and MATs deregulation represent potential therapeutic targets for HCC. Finally, MATI/III:MATII ratio strongly predicts patients' survival length suggesting that MAT1A:MAT2A expression ratio is a putative prognostic marker for human HCC.
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Affiliation(s)
- Maddalena Frau
- Department of Clinical and Experimental Medicine, Laboratory of Experimental Pathology and Oncology, University of Sassari, Sassari, Italy
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