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Shi MM, Xu XF, Sun QM, Luo M, Liu DD, Guo DM, Chen L, Zhong XL, Xu Y, Cao WY. Betaine prevents cognitive dysfunction by suppressing hippocampal microglial activation in chronic social isolated male mice. Phytother Res 2023; 37:4755-4770. [PMID: 37846157 DOI: 10.1002/ptr.7944] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 06/22/2023] [Accepted: 06/23/2023] [Indexed: 10/18/2023]
Abstract
Chronic social isolation (SI) stress, which became more prevalent during the COVID-19 pandemic, contributes to abnormal behavior, including mood changes and cognitive impairment. Known as a functional nutrient, betaine has potent antioxidant and anti-inflammatory properties in vivo. However, whether betaine can alleviate the abnormal behavior induced by chronic SI in mice remains unknown. In this study, we investigated the efficacy of betaine in the treatment of behavioral changes and its underlying mechanism. Three-week-old male mice were randomly housed for 8 weeks in either group housing (GH) or SI. The animals were divided into normal saline-treated GH, normal saline-treated SI, and betaine-treated SI groups in the sixth week. The cognitive and depression-like behavior was determined in the eighth week. We found that long-term betaine administration improved cognitive behavior in SI mice but failed to prevent depression-like behavior. Moreover, long-term betaine administration inhibited hippocampal microglia over-activation and polarized microglia toward the M2 phenotype, which effectively inhibited the expression of inflammatory factors in SI mice. Finally, the protective effect of betaine treatment in SI mice might not be due to altered activity of the hypothalamic-pituitary-adrenal axis. Collectively, our findings reveal that betaine can improve SI-induced cognitive impairment, thus providing an alternative natural source for the prevention of memory loss caused by SI or loneliness.
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Affiliation(s)
- Meng Meng Shi
- Clinical Anatomy and Reproductive Medicine Application Institute, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Xiao Fan Xu
- Clinical Anatomy and Reproductive Medicine Application Institute, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Qiu Min Sun
- Department of Nursing, Yiyang Medical College, Yiyang, Hunan, China
| | - Mingying Luo
- Department of Anatomy and Histology and Embryology, Kunming Medical University, Kunming, Yunnan, China
| | - Dan Dan Liu
- Institute of Clinical Medicine, The First Affiliated Hospital of the University of South China, Hengyang, Hunan, China
| | - Dong Min Guo
- Clinical Anatomy and Reproductive Medicine Application Institute, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Ling Chen
- Institute of Clinical Medicine, The First Affiliated Hospital of the University of South China, Hengyang, Hunan, China
| | - Xiao Lin Zhong
- Institute of Clinical Medicine, The First Affiliated Hospital of the University of South China, Hengyang, Hunan, China
| | - Yang Xu
- Institute of Neuroscience, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Wen Yu Cao
- Clinical Anatomy and Reproductive Medicine Application Institute, Hengyang Medical School, University of South China, Hengyang, Hunan, China
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Li J, Wang X, Lan T, Lu Y, Hong M, Ding L, Wang L. CDK5/NFAT5-Regulated Transporters Involved in Osmoregulation in Fejervarya cancrivora. BIOLOGY 2022; 11:biology11060858. [PMID: 35741379 PMCID: PMC9220195 DOI: 10.3390/biology11060858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/30/2022] [Accepted: 06/01/2022] [Indexed: 11/19/2022]
Abstract
Crab-eating frogs (Fejervarya cancrivora) can live in brackish water with a salinity of up to 18‱, although most amphibians are not able to tolerate such high saline environments. To investigate its potential osmoregulation, we conducted experiments in F. cancrivora and F. multistriata. The results showed that F. cancrivora made use of ions (such as Na+ and Cl−) to increase intracellular concentrations via the Na+/K+-ATPase (NKA) enzyme. The mRNA expression of aldose reductase (AR) was significantly higher in F. cancrivora (p < 0.05), indicating that more organic osmolytes were produced and transported to maintain cellular homeosis. The mRNA expressions of Aquaporin 1 (AQP1) and AQP3 in kidney were significantly higher in F. cancrivora, while AQP expression in skin was higher in F. multistriata (p < 0.05). The mRNA level in activating the transcription of the nuclear factor of activated T cells-5 (NFAT5) which is one of the target genes of regulating the cellular response to hypertonicity, was higher in F. cancrivora. The protein expression of CDK5, the upstream protein of the NFAT5 pathway, was 2 times higher in F. cancrivora. Therefore, we can conclude that CDK5/NFAT5-regulated transporters might be involved in osmoregulation in F. cancrivora.
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Affiliation(s)
| | | | | | | | | | - Li Ding
- Correspondence: (L.D.); (L.W.)
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The PKA-p38MAPK-NFAT5-Organic Osmolytes Pathway in Duchenne Muscular Dystrophy: From Essential Player in Osmotic Homeostasis, Inflammation and Skeletal Muscle Regeneration to Therapeutic Target. Biomedicines 2021; 9:biomedicines9040350. [PMID: 33808305 PMCID: PMC8066813 DOI: 10.3390/biomedicines9040350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/19/2021] [Accepted: 03/24/2021] [Indexed: 11/30/2022] Open
Abstract
In Duchenne muscular dystrophy (DMD), the absence of dystrophin from the dystrophin-associated protein complex (DAPC) causes muscle membrane instability, which leads to myofiber necrosis, hampered regeneration, and chronic inflammation. The resulting disabled DAPC-associated cellular pathways have been described both at the molecular and the therapeutical level, with the Toll-like receptor nuclear factor kappa-light-chain-enhancer of activated B cells pathway (NF-ƘB), Janus kinase/signal transducer and activator of transcription proteins, and the transforming growth factor-β pathways receiving the most attention. In this review, we specifically focus on the protein kinase A/ mitogen-activated protein kinase/nuclear factor of activated T-cells 5/organic osmolytes (PKA-p38MAPK-NFAT5-organic osmolytes) pathway. This pathway plays an important role in osmotic homeostasis essential to normal cell physiology via its regulation of the influx/efflux of organic osmolytes. Besides, NFAT5 plays an essential role in cell survival under hyperosmolar conditions, in skeletal muscle regeneration, and in tissue inflammation, closely interacting with the master regulator of inflammation NF-ƘB. We describe the involvement of the PKA-p38MAPK-NFAT5-organic osmolytes pathway in DMD pathophysiology and provide a clear overview of which therapeutic molecules could be of potential benefit to DMD patients. We conclude that modulation of the PKA-p38MAPK-NFAT5-organic osmolytes pathway could be developed as supportive treatment for DMD in conjunction with genetic therapy.
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Functional Expression of Choline Transporters in Human Neural Stem Cells and Its Link to Cell Proliferation, Cell Viability, and Neurite Outgrowth. Cells 2021; 10:cells10020453. [PMID: 33672580 PMCID: PMC7924032 DOI: 10.3390/cells10020453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 01/11/2023] Open
Abstract
Choline and choline metabolites are essential for all cellular functions. They have also been reported to be crucial for neural development. In this work, we studied the functional characteristics of the choline uptake system in human neural stem cells (hNSCs). Additionally, we investigated the effect of extracellular choline uptake inhibition on the cellular activities in hNSCs. We found that the mRNAs and proteins of choline transporter-like protein 1 (CTL1) and CTL2 were expressed at high levels. Immunostaining showed that CTL1 and CTL2 were localized in the cell membrane and partly in the mitochondria, respectively. The uptake of extracellular choline was saturable and performed by a single uptake mechanism, which was Na+-independent and pH-dependent. We conclude that CTL1 is responsible for extracellular choline uptake, and CTL2 may uptake choline in the mitochondria and be involved in DNA methylation via choline oxidation. Extracellular choline uptake inhibition caused intracellular choline deficiency in hNSCs, which suppressed cell proliferation, cell viability, and neurite outgrowth. Our findings contribute to the understanding of the role of choline in neural development as well as the pathogenesis of various neurological diseases caused by choline deficiency or choline uptake impairment.
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Ohnishi T, Balan S, Toyoshima M, Maekawa M, Ohba H, Watanabe A, Iwayama Y, Fujita Y, Tan Y, Hisano Y, Shimamoto-Mitsuyama C, Nozaki Y, Esaki K, Nagaoka A, Matsumoto J, Hino M, Mataga N, Hayashi-Takagi A, Hashimoto K, Kunii Y, Kakita A, Yabe H, Yoshikawa T. Investigation of betaine as a novel psychotherapeutic for schizophrenia. EBioMedicine 2019; 45:432-446. [PMID: 31255657 PMCID: PMC6642071 DOI: 10.1016/j.ebiom.2019.05.062] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 05/24/2019] [Accepted: 05/30/2019] [Indexed: 12/18/2022] Open
Abstract
Background Betaine is known to act against various biological stresses and its levels were reported to be decreased in schizophrenia patients. We aimed to test the role of betaine in schizophrenia pathophysiology, and to evaluate its potential as a novel psychotherapeutic. Methods Using Chdh (a gene for betaine synthesis)-deficient mice and betaine-supplemented inbred mice, we assessed the role of betaine in psychiatric pathophysiology, and its potential as a novel psychotherapeutic, by leveraging metabolomics, behavioral-, transcriptomics and DNA methylation analyses. Findings The Chdh-deficient mice revealed remnants of psychiatric behaviors along with schizophrenia-related molecular perturbations in the brain. Betaine supplementation elicited genetic background-dependent improvement in cognitive performance, and suppressed methamphetamine (MAP)-induced behavioral sensitization. Furthermore, betaine rectified the altered antioxidative and proinflammatory responses induced by MAP and in vitro phencyclidine (PCP) treatments. Betaine also showed a prophylactic effect on behavioral abnormality induced by PCP. Notably, betaine levels were decreased in the postmortem brains from schizophrenia, and a coexisting elevated carbonyl stress, a form of oxidative stress, demarcated a subset of schizophrenia with “betaine deficit-oxidative stress pathology”. We revealed the decrease of betaine levels in glyoxylase 1 (GLO1)-deficient hiPSCs, which shows elevated carbonyl stress, and the efficacy of betaine in alleviating it, thus supporting a causal link between betaine and oxidative stress conditions. Furthermore, a CHDH variant, rs35518479, was identified as a cis-expression quantitative trait locus (QTL) for CHDH expression in postmortem brains from schizophrenia, allowing genotype-based stratification of schizophrenia patients for betaine efficacy. Interpretation The present study revealed the role of betaine in psychiatric pathophysiology and underscores the potential benefit of betaine in a subset of schizophrenia. Fund This study was supported by the Strategic Research Program for Brain Sciences from AMED (Japan Agency for Medical Research and Development) under Grant Numbers JP18dm0107083 and JP19dm0107083 (TY), JP18dm0107129 (MM), JP18dm0107086 (YK), JP18dm0107107 (HY), JP18dm0107104 (AK) and JP19dm0107119 (KH), by the Grant-in-Aid for Scientific Research on Innovative Areas from the MEXT under Grant Numbers JP18H05435 (TY), JP18H05433 (AH.-T), JP18H05428 (AH.-T and TY), and JP16H06277 (HY), and by JSPS KAKENHI under Grant Number JP17H01574 (TY). In addition, this study was supported by the Collaborative Research Project of Brain Research Institute, Niigata University under Grant Numbers 2018–2809 (YK) and RIKEN Epigenetics Presidential Fund (100214–201801063606-340120) (TY).
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Affiliation(s)
- Tetsuo Ohnishi
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Shabeesh Balan
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Manabu Toyoshima
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Motoko Maekawa
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Hisako Ohba
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Akiko Watanabe
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Yoshimi Iwayama
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan; Support Unit for Bio-Material Analysis, Research Resources Division, RIKEN Center for Brain Science, Saitama, Japan
| | - Yuko Fujita
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| | - Yunfei Tan
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| | - Yasuko Hisano
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | | | - Yayoi Nozaki
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Kayoko Esaki
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan
| | - Atsuko Nagaoka
- Department of Neuropsychiatry, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Junya Matsumoto
- Department of Neuropsychiatry, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Mizuki Hino
- Department of Neuropsychiatry, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Nobuko Mataga
- Support Unit for Bio-Material Analysis, Research Resources Division, RIKEN Center for Brain Science, Saitama, Japan
| | - Akiko Hayashi-Takagi
- Laboratory of Medical Neuroscience, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
| | - Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| | - Yasuto Kunii
- Department of Neuropsychiatry, School of Medicine, Fukushima Medical University, Fukushima, Japan; Department of Psychiatry, Aizu Medical Center, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Akiyoshi Kakita
- Department of Pathology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Hirooki Yabe
- Department of Neuropsychiatry, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Takeo Yoshikawa
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Saitama, Japan.
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Zeisel SH, Klatt KC, Caudill MA. Choline. Adv Nutr 2018; 9:58-60. [PMID: 29438456 PMCID: PMC6008955 DOI: 10.1093/advances/nmx004] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 08/16/2017] [Accepted: 10/12/2017] [Indexed: 12/24/2022] Open
Affiliation(s)
- Steven H Zeisel
- UNC Nutrition Research Institute, Department of Nutrition, School of Public Health and School of Medicine, University of North Carolina at Chapel Hill, Kannapolis, NC
| | - Kevin C Klatt
- Division of Nutritional Sciences, Cornell University, Ithaca, NY
| | - Marie A Caudill
- Division of Nutritional Sciences, Cornell University, Ithaca, NY
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Nielsen CU, Rasmussen RN, Mo J, Noori B, Lagunas C, Holm R, Nøhr MK. A Transporter of Ibuprofen is Upregulated in MDCK I Cells under Hyperosmotic Culture Conditions. Mol Pharm 2016; 13:3119-29. [PMID: 27396755 DOI: 10.1021/acs.molpharmaceut.6b00330] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ibuprofen is a widely used drug. It has been identified as an inhibitor of several transporters, but it is not clear if ibuprofen is a substrate of any transporter itself. In the present work, we have characterized a transporter of ibuprofen, which is upregulated by hyperosmotic culture conditions in Madin-Darby canine kidney I (MDCK I) renal cells. [(3)H]-Ibuprofen uptake rate was measured in MDCK I cell cultured under normal (300 mOsm) and hyperosmotic (500 mOsm) conditions. Hyperosmotic conditions were obtained by supplementing urea, NaCl, mannitol, or raffinose to culture medium. The effect of increased osmolarity was investigated for different incubation times. [(3)H]-Ibuprofen uptake in MDCK I cells was upregulated by hyperosmotic culture condition, and was saturable with a Km value of 0.37 ± 0.08 μM and a Vmax of 233.1 ± 17.2 pmol· cm(-2)· min(-1). Racemic [(3)H]-ibuprofen uptake could be inhibited by (R)-(-)- and (S)-(+)-ibuprofen with IC50 values of 19 μM (Log IC50 1.39 ± 0.34) and 0.47 μM (Log IC50 -0.36 ± 0.41), respectively. Furthermore, the [(3)H]-ibuprofen uptake rate was increased by decreased extracellular pH but not dependent on Na(+) or Cl(-) ions. The mRNA of Mct1, -2, -4, and -6 as well as Oat1 and -3 were not upregulated by hyperosmolarity. Our findings present strong evidence for the presence of a yet unknown ibuprofen transporter in MDCK I cells. The transporter was upregulated under hyperosmotic culture conditions, and the present study is therefore a starting point for identification of the molecular correlate and potential impact on ibuprofen disposition.
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Affiliation(s)
- Carsten Uhd Nielsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Campusvej 55, DK-5230 Odense M, Denmark
| | - Rune N Rasmussen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Campusvej 55, DK-5230 Odense M, Denmark
| | - Junying Mo
- Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Benafsha Noori
- Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Candela Lagunas
- Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - René Holm
- Pharmaceutical Science and CMC Biologics, H. Lundbeck A/S , DK-2500 Valby, Denmark
| | - Martha K Nøhr
- Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark
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Role of N-glycosylation in renal betaine transport. Biochem J 2015; 470:169-79. [PMID: 26348906 DOI: 10.1042/bj20131031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 06/03/2015] [Indexed: 11/17/2022]
Abstract
The osmolyte and folding chaperone betaine is transported by the renal Na(+)-coupled GABA (γ-aminobutyric acid) symporter BGT-1 (betaine/GABA transporter 1), a member of the SLC6 (solute carrier 6) family. Under hypertonic conditions, the transcription, translation and plasma membrane (PM) insertion of BGT-1 in kidney cells are significantly increased, resulting in elevated betaine and GABA transport. Re-establishing isotonicity involves PM depletion of BGT-1. The molecular mechanism of the regulated PM insertion of BGT-1 during changes in osmotic stress is unknown. In the present study, we reveal a link between regulated PM insertion and N-glycosylation. Based on homology modelling, we identified two sites (Asn(171) and Asn(183)) in the extracellular loop 2 (EL2) of BGT-1, which were investigated with respect to trafficking, insertion and transport by immunogold-labelling, electron microscopy (EM), mutagenesis and two-electrode voltage clamp measurements in Xenopus laevis oocytes and uptake of radiolabelled substrate into MDCK (Madin-Darby canine kidney) and HEK293 (human embryonic kidney) cells. Trafficking and PM insertion of BGT-1 was clearly promoted by N-glycosylation in both oocytes and MDCK cells. Moreover, association with N-glycans at Asn(171) and Asn(183) contributed equally to protein activity and substrate affinity. Substitution of Asn(171) and Asn(183) by aspartate individually caused no loss of BGT-1 activity, whereas the double mutant was inactive, suggesting that N-glycosylation of at least one of the sites is required for function. Substitution by alanine or valine at either site caused a dramatic loss in transport activity. Furthermore, in MDCK cells PM insertion of N183D was no longer regulated by osmotic stress, highlighting the impact of N-glycosylation in regulation of this SLC6 transporter.
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Abstract
We demonstrated in the present study that betaine-homocysteine (Hcy) methyltransferase (BHMT) is a major pathway for Hcy removal in all situations of hyperhomocysteinaemia (HHcy). Hperhomocysteinaemia induces betaine depletion in plasma and tissues except in kidney, where betaine may play a crucial role as an osmolyte. Betaine is the substrate of the liver- and kidney-specific betaine-homocysteine (Hcy) methyltransferase (BHMT), an alternate pathway for Hcy remethylation. We hypothesized that BHMT is a major pathway for homocysteine removal in cases of hyperhomocysteinaemia (HHcy). Therefore, we measured betaine in plasma and tissues from patients and animal models of HHcy of genetic and acquired cause. Plasma was collected from patients presenting HHcy without any Hcy interfering treatment. Plasma and tissues were collected from rat models of HHcy induced by diet and from a mouse model of cystathionine β-synthase (CBS) deficiency. S-adenosyl-methionine (AdoMet), S-adenosyl-homocysteine (AdoHcy), methionine, betaine and dimethylglycine (DMG) were quantified by ESI—LC–MS/MS. mRNA expression was quantified using quantitative real-time (QRT)-PCR. For all patients with diverse causes of HHcy, plasma betaine concentrations were below the normal values of our laboratory. In the diet-induced HHcy rat model, betaine was decreased in all tissues analysed (liver, brain, heart). In the mouse CBS deficiency model, betaine was decreased in plasma, liver, heart and brain, but was conserved in kidney. Surprisingly, BHMT expression and activity was decreased in liver. However, in kidney, BHMT and SLC6A12 expression was increased in CBS-deficient mice. Chronic HHcy, irrespective of its cause, induces betaine depletion in plasma and tissues (liver, brain and heart), indicating a global decrease in the body betaine pool. In kidney, betaine concentrations were not affected, possibly due to overexpression of the betaine transporter SLC6A12 where betaine may be conserved because of its crucial role as an osmolyte.
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10
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Andronic J, Shirakashi R, Pickel SU, Westerling KM, Klein T, Holm T, Sauer M, Sukhorukov VL. Hypotonic activation of the myo-inositol transporter SLC5A3 in HEK293 cells probed by cell volumetry, confocal and super-resolution microscopy. PLoS One 2015; 10:e0119990. [PMID: 25756525 PMCID: PMC4355067 DOI: 10.1371/journal.pone.0119990] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 01/21/2015] [Indexed: 11/19/2022] Open
Abstract
Swelling-activated pathways for myo-inositol, one of the most abundant organic osmolytes in mammalian cells, have not yet been identified. The present study explores the SLC5A3 protein as a possible transporter of myo-inositol in hyponically swollen HEK293 cells. To address this issue, we examined the relationship between the hypotonicity-induced changes in plasma membrane permeability to myo-inositol Pino [m/s] and expression/localization of SLC5A3. Pino values were determined by cell volumetry over a wide tonicity range (100–275 mOsm) in myo-inositol-substituted solutions. While being negligible under mild hypotonicity (200–275 mOsm), Pino grew rapidly at osmolalities below 200 mOsm to reach a maximum of ∼3 nm/s at 100–125 mOsm, as indicated by fast cell swelling due to myo-inositol influx. The increase in Pino resulted most likely from the hypotonicity-mediated incorporation of cytosolic SLC5A3 into the plasma membrane, as revealed by confocal fluorescence microscopy of cells expressing EGFP-tagged SLC5A3 and super-resolution imaging of immunostained SLC5A3 by direct stochastic optical reconstruction microscopy (dSTORM). dSTORM in hypotonic cells revealed a surface density of membrane-associated SLC5A3 proteins of 200–2000 localizations/μm2. Assuming SLC5A3 to be the major path for myo-inositol, a turnover rate of 80–800 myo-inositol molecules per second for a single transporter protein was estimated from combined volumetric and dSTORM data. Hypotonic stress also caused a significant upregulation of SLC5A3 gene expression as detected by semiquantitative RT-PCR and Western blot analysis. In summary, our data provide first evidence for swelling-mediated activation of SLC5A3 thus suggesting a functional role of this transporter in hypotonic volume regulation of mammalian cells.
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Affiliation(s)
- Joseph Andronic
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Ryo Shirakashi
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - Simone U. Pickel
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Katherine M. Westerling
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Teresa Klein
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Thorge Holm
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Vladimir L. Sukhorukov
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
- * E-mail:
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11
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Luan Z, Quigley C, Li HS. The putative Na⁺/Cl⁻-dependent neurotransmitter/osmolyte transporter inebriated in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis. Sci Rep 2015; 5:7993. [PMID: 25613130 PMCID: PMC4303880 DOI: 10.1038/srep07993] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 12/29/2014] [Indexed: 11/24/2022] Open
Abstract
Most organisms are able to maintain systemic water homeostasis over a wide range of external or dietary osmolarities. The excretory system, composed of the kidneys in mammals and the Malpighian tubules and hindgut in insects, can increase water conservation and absorption to maintain systemic water homeostasis, which enables organisms to tolerate external hypertonicity or desiccation. However, the mechanisms underlying the maintenance of systemic water homeostasis by the excretory system have not been fully characterized. In the present study, we found that the putative Na+/Cl−-dependent neurotransmitter/osmolyte transporter inebriated (ine) is expressed in the basolateral membrane of anterior hindgut epithelial cells. This was confirmed by comparison with a known basolateral localized protein, the α subunit of Na+-K+ ATPase (ATPα). Under external hypertonicity, loss of ine in the hindgut epithelium results in severe dehydration without damage to the hindgut epithelial cells, implicating a physiological failure of water conservation/absorption. We also found that hindgut expression of ine is required for water conservation under desiccating conditions. Importantly, specific expression of ine in the hindgut epithelium can completely restore disrupted systemic water homeostasis in ine mutants under both conditions. Therefore, ine in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis.
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Affiliation(s)
- Zhuo Luan
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Caitlin Quigley
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Hong-Sheng Li
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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12
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Kempson SA, Zhou Y, Danbolt NC. The betaine/GABA transporter and betaine: roles in brain, kidney, and liver. Front Physiol 2014; 5:159. [PMID: 24795654 PMCID: PMC4006062 DOI: 10.3389/fphys.2014.00159] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/04/2014] [Indexed: 12/18/2022] Open
Abstract
The physiological roles of the betaine/GABA transporter (BGT1; slc6a12) are still being debated. BGT1 is a member of the solute carrier family 6 (the neurotransmitter, sodium symporter transporter family) and mediates cellular uptake of betaine and GABA in a sodium- and chloride-dependent process. Most of the studies of BGT1 concern its function and regulation in the kidney medulla where its role is best understood. The conditions here are hostile due to hyperosmolarity and significant concentrations of NH4Cl and urea. To withstand the hyperosmolarity, cells trigger osmotic adaptation, involving concentration of a transcriptional factor TonEBP/NFAT5 in the nucleus, and accumulate betaine and other osmolytes. Data from renal cells in culture, primarily MDCK, revealed that transcriptional regulation of BGT1 by TonEBP/NFAT5 is relatively slow. To allow more acute control of the abundance of BGT1 protein in the plasma membrane, there is also post-translation regulation of BGT1 protein trafficking which is dependent on intracellular calcium and ATP. Further, betaine may be important in liver metabolism as a methyl donor. In fact, in the mouse the liver is the organ with the highest content of BGT1. Hepatocytes express high levels of both BGT1 and the only enzyme that can metabolize betaine, namely betaine:homocysteine –S-methyltransferase (BHMT1). The BHMT1 enzyme removes a methyl group from betaine and transfers it to homocysteine, a potential risk factor for cardiovascular disease. Finally, BGT1 has been proposed to play a role in controlling brain excitability and thereby represents a target for anticonvulsive drug development. The latter hypothesis is controversial due to very low expression levels of BGT1 relative to other GABA transporters in brain, and also the primary location of BGT1 at the surface of the brain in the leptomeninges. These issues are discussed in detail.
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Affiliation(s)
- Stephen A Kempson
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine Indianapolis, IN, USA
| | - Yun Zhou
- Department of Anatomy, Centre of Molecular Biology and Neuroscience, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Niels C Danbolt
- Department of Anatomy, Centre of Molecular Biology and Neuroscience, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
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A Single Amino Acid Substitution in the Renal Betaine/GABA Transporter Prevents Trafficking to the Plasma Membrane. ACTA ACUST UNITED AC 2013. [DOI: 10.1155/2013/598321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
One response to hypertonic stress in the renal medulla and MDCK cells is the upregulation of betaine transporter (BGT1) synthesis, followed by trafficking to the plasma membrane (PM) and an increase in betaine transport. Upregulation of BGT1 was enhanced by inhibitors of phosphatases PP1 and PP2A and was attenuated by inhibitors of protein kinase C, suggesting an important role for phosphorylation reactions. This was tested using mutants of BGT1 tagged with EGFP. The PM trafficking motifs of BGT1 reside near the C terminus, and truncation at lysine560 resulted in a protein that remained intracellular during hypertonic stress. This K560Δ mutant colocalized with endoplasmic reticulum (ER). Substitution of alanine at Thr40, a putative phosphorylation site, also prevented trafficking to the PM during hypertonic stress. Live-cell imaging showed that T40A was not retained in the ER and colocalized with markers for Golgi and endosomes. In contrast, substitution of aspartate or glutamate at Thr40, to mimic phosphorylation, restored normal trafficking to the PM. HEK293 cells transfected with K560Δ or T40A mutants had 10% of the GABA transport activity of native BGT1, but normal transport activity was restored in cells expressing T40E. Normal BGT1 trafficking likely requires phosphorylation at Thr40 in addition to C-terminal motifs.
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Phosphatidylcholine and the CDP-choline cycle. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:523-32. [PMID: 23010477 DOI: 10.1016/j.bbalip.2012.09.009] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 09/16/2012] [Indexed: 11/20/2022]
Abstract
The CDP-choline pathway of phosphatidylcholine (PtdCho) biosynthesis was first described more than 50 years ago. Investigation of the CDP-choline pathway in yeast provides a basis for understanding the CDP-choline pathway in mammals. PtdCho is considered as an intermediate in a cycle of synthesis and degradation, and the activity of a CDP-choline cycle is linked to subcellular membrane lipid movement. The components of the mammalian CDP-choline pathway include choline transport, choline kinase, phosphocholine cytidylyltransferase, and choline phosphotransferase activities. The protein isoforms and biochemical mechanisms of regulation of the pathway enzymes are related to their cell- and tissue-specific functions. Regulated PtdCho turnover mediated by phospholipases or neuropathy target esterase participates in the mammalian CDP-choline cycle. Knockout mouse models define the biological functions of the CDP-choline cycle in mammalian cells and tissues. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Miwa M, Tsuboi M, Noguchi Y, Enokishima A, Nabeshima T, Hiramatsu M. Effects of betaine on lipopolysaccharide-induced memory impairment in mice and the involvement of GABA transporter 2. J Neuroinflammation 2011; 8:153. [PMID: 22053950 PMCID: PMC3273450 DOI: 10.1186/1742-2094-8-153] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 11/04/2011] [Indexed: 11/15/2022] Open
Abstract
Background Betaine (glycine betaine or trimethylglycine) plays important roles as an osmolyte and a methyl donor in animals. While betaine is reported to suppress expression of proinflammatory molecules and reduce oxidative stress in aged rat kidney, the effects of betaine on the central nervous system are not well known. In this study, we investigated the effects of betaine on lipopolysaccharide (LPS)-induced memory impairment and on mRNA expression levels of proinflammatory molecules, glial markers, and GABA transporter 2 (GAT2), a betaine/GABA transporter. Methods Mice were continuously treated with betaine for 13 days starting 1 day before they were injected with LPS, or received subacute or acute administration of betaine shortly before or after LPS injection. Then, their memory function was evaluated using Y-maze and novel object recognition tests 7 and 10-12 days after LPS injection (30 μg/mouse, i.c.v.), respectively. In addition, mRNA expression levels in hippocampus were measured by real-time RT-PCR at different time points. Results Repeated administration of betaine (0.163 mmol/kg, s.c.) prevented LPS-induced memory impairment. GAT2 mRNA levels were significantly increased in hippocampus 24 hr after LPS injection, and administration of betaine blocked this increase. However, betaine did not affect LPS-induced increases in levels of mRNA related to inflammatory responses. Both subacute administration (1 hr before, and 1 and 24 hr after LPS injection) and acute administration (1 hr after LPS injection) of betaine also prevented LPS-induced memory impairment in the Y-maze test. Conclusions These data suggest that betaine has protective effects against LPS-induced memory impairment and that prevention of LPS-induced changes in GAT2 mRNA expression is crucial to this ameliorating effect.
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Affiliation(s)
- Masaya Miwa
- Laboratory of Neuropsychopharmacology, Graduate School of Environmental and Human Sciences, Meijo University, 150 Yagotoyama, Tenpaku-ku, Nagoya 468-8503, Japan
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Lehre A, Rowley N, Zhou Y, Holmseth S, Guo C, Holen T, Hua R, Laake P, Olofsson A, Poblete-Naredo I, Rusakov D, Madsen K, Clausen R, Schousboe A, White H, Danbolt N. Deletion of the betaine-GABA transporter (BGT1; slc6a12) gene does not affect seizure thresholds of adult mice. Epilepsy Res 2011; 95:70-81. [PMID: 21459558 PMCID: PMC3376448 DOI: 10.1016/j.eplepsyres.2011.02.014] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 02/02/2011] [Accepted: 02/27/2011] [Indexed: 10/18/2022]
Abstract
Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian brain. Once released, it is removed from the extracellular space by cellular uptake catalyzed by GABA transporter proteins. Four GABA transporters (GAT1, GAT2, GAT3 and BGT1) have been identified. Inhibition of the GAT1 by the clinically available anti-epileptic drug tiagabine has been an effective strategy for the treatment of some patients with partial seizures. Recently, the investigational drug EF1502, which inhibits both GAT1 and BGT1, was found to exert an anti-convulsant action synergistic to that of tiagabine, supposedly due to inhibition of BGT1. The present study addresses the role of BGT1 in seizure control and the effect of EF1502 by developing and exploring a new mouse line lacking exons 3-5 of the BGT1 (slc6a12) gene. The deletion of this sequence abolishes the expression of BGT1 mRNA. However, homozygous BGT1-deficient mice have normal development and show seizure susceptibility indistinguishable from that in wild-type mice in a variety of seizure threshold models including: corneal kindling, the minimal clonic and minimal tonic extension seizure threshold tests, the 6Hz seizure threshold test, and the i.v. pentylenetetrazol threshold test. We confirm that BGT1 mRNA is present in the brain, but find that the levels are several hundred times lower than those of GAT1 mRNA; possibly explaining the apparent lack of phenotype. In conclusion, the present results do not support a role for BGT1 in the control of seizure susceptibility and cannot provide a mechanistic understanding of the synergism that has been previously reported with tiagabine and EF1502.
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Affiliation(s)
- A.C. Lehre
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105 Blindern, N-0317 Oslo, Norway
| | - N.M. Rowley
- Department of Pharmacology and Toxicology, Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, USA
| | - Y. Zhou
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105 Blindern, N-0317 Oslo, Norway
| | - S. Holmseth
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105 Blindern, N-0317 Oslo, Norway
| | - C. Guo
- HHMI, Janelia Farm Research Campus, Ashburn, VA, USA
| | - T. Holen
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105 Blindern, N-0317 Oslo, Norway
| | - R. Hua
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105 Blindern, N-0317 Oslo, Norway
| | - P. Laake
- Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - A.M. Olofsson
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105 Blindern, N-0317 Oslo, Norway
| | - I. Poblete-Naredo
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, México D.F., Mexico
| | - D.A. Rusakov
- UCL Institute of Neurology, University College London, UK
| | - K.K. Madsen
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical sciences, University of Copenhagen, Denmark
| | - R.P. Clausen
- Department of medicinal chemistry, Faculty of Pharmaceutical sciences, University of Copenhagen, Denmark
| | - A. Schousboe
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical sciences, University of Copenhagen, Denmark
| | - H.S. White
- Department of Pharmacology and Toxicology, Anticonvulsant Drug Development Program, University of Utah, Salt Lake City, UT, USA
| | - N.C. Danbolt
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105 Blindern, N-0317 Oslo, Norway
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Sha W, da Costa KA, Fischer LM, Milburn MV, Lawton KA, Berger A, Jia W, Zeisel SH. Metabolomic profiling can predict which humans will develop liver dysfunction when deprived of dietary choline. FASEB J 2010; 24:2962-75. [PMID: 20371621 DOI: 10.1096/fj.09-154054] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Choline is an essential nutrient, and deficiency causes liver and muscle dysfunction. Common genetic variations alter the risk of developing organ dysfunction when choline deficient, probably by causing metabolic inefficiencies that should be detectable even while ingesting a normal choline-adequate diet. We determined whether metabolomic profiling of plasma at baseline could predict whether humans will develop liver dysfunction when deprived of dietary choline. Fifty-three participants were fed a diet containing 550 mg choline/70 kg/d for 10 d and then fed < 50 mg choline/70 kg/d for up to 42 d. Participants who developed organ dysfunction on this diet were repleted with a choline-adequate diet for > or = 3 d. Plasma samples, obtained at baseline, end of depletion, and end of repletion, were used for targeted and nontargeted metabolomic profiling. Liver fat was assessed using magnetic resonance spectroscopy. Metabolomic profiling and targeted biochemical analyses were highly correlated for the analytes assessed by both procedures. In addition, we report relative concentration changes of other small molecules detected by the nontargeted metabolomic analysis after choline depletion. Finally, we show that metabolomic profiles of participants when they were consuming a control baseline diet could predict whether they would develop liver dysfunction when deprived of dietary choline.
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Affiliation(s)
- Wei Sha
- Bioinformatics Research Center, University of North Carolina at Charlotte, USA
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Deo RC, Hunter L, Lewis GD, Pare G, Vasan RS, Chasman D, Wang TJ, Gerszten RE, Roth FP. Interpreting metabolomic profiles using unbiased pathway models. PLoS Comput Biol 2010; 6:e1000692. [PMID: 20195502 PMCID: PMC2829050 DOI: 10.1371/journal.pcbi.1000692] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 01/26/2010] [Indexed: 11/18/2022] Open
Abstract
Human disease is heterogeneous, with similar disease phenotypes resulting from distinct combinations of genetic and environmental factors. Small-molecule profiling can address disease heterogeneity by evaluating the underlying biologic state of individuals through non-invasive interrogation of plasma metabolite levels. We analyzed metabolite profiles from an oral glucose tolerance test (OGTT) in 50 individuals, 25 with normal (NGT) and 25 with impaired glucose tolerance (IGT). Our focus was to elucidate underlying biologic processes. Although we initially found little overlap between changed metabolites and preconceived definitions of metabolic pathways, the use of unbiased network approaches identified significant concerted changes. Specifically, we derived a metabolic network with edges drawn between reactant and product nodes in individual reactions and between all substrates of individual enzymes and transporters. We searched for "active modules"--regions of the metabolic network enriched for changes in metabolite levels. Active modules identified relationships among changed metabolites and highlighted the importance of specific solute carriers in metabolite profiles. Furthermore, hierarchical clustering and principal component analysis demonstrated that changed metabolites in OGTT naturally grouped according to the activities of the System A and L amino acid transporters, the osmolyte carrier SLC6A12, and the mitochondrial aspartate-glutamate transporter SLC25A13. Comparison between NGT and IGT groups supported blunted glucose- and/or insulin-stimulated activities in the IGT group. Using unbiased pathway models, we offer evidence supporting the important role of solute carriers in the physiologic response to glucose challenge and conclude that carrier activities are reflected in individual metabolite profiles of perturbation experiments. Given the involvement of transporters in human disease, metabolite profiling may contribute to improved disease classification via the interrogation of specific transporter activities.
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Affiliation(s)
- Rahul C. Deo
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
- Cardiology Division, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Luke Hunter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Gregory D. Lewis
- Cardiology Division, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Guillaume Pare
- Center for Cardiovascular Disease Prevention, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Donald W. Reynolds Center for Cardiovascular Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Ramachandran S. Vasan
- Framingham Heart Study, National Heart, Lung, and Blood Institute and Boston University, Boston, Massachusetts, United States of America
- Sections of Cardiology and Preventive Medicine, and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Daniel Chasman
- Center for Cardiovascular Disease Prevention, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Donald W. Reynolds Center for Cardiovascular Research, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Thomas J. Wang
- Cardiology Division, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Framingham Heart Study, National Heart, Lung, and Blood Institute and Boston University, Boston, Massachusetts, United States of America
| | - Robert E. Gerszten
- Cardiology Division, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Center for Immunology and Inflammatory Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Frederick P. Roth
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Fischer LM, daCosta KA, Kwock L, Stewart PW, Lu TS, Stabler SP, Allen RH, Zeisel SH. Sex and menopausal status influence human dietary requirements for the nutrient choline. Am J Clin Nutr 2007; 85:1275-85. [PMID: 17490963 PMCID: PMC2435503 DOI: 10.1093/ajcn/85.5.1275] [Citation(s) in RCA: 212] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Although humans require dietary choline for methyl donation, membrane function, and neurotransmission, choline can also be derived from the de novo synthesis of phosphatidylcholine, which is up-regulated by estrogen. A recommended Adequate Intake (AI) exists for choline; however, an Estimated Average Requirement has not been set because of a lack of sufficient human data. OBJECTIVE The objective of the study was to evaluate the dietary requirements for choline in healthy men and women and to investigate the clinical sequelae of choline deficiency. DESIGN Fifty-seven adult subjects (26 men, 16 premenopausal women, 15 postmenopausal women) were fed a diet containing 550 mg choline x 70 kg(-1) x d(-1) for 10 d followed by <50 mg choline x 70 kg(-1) x d(-1) with or without a folic acid supplement (400 microg/d per randomization) for up to 42 d. Subjects who developed organ dysfunction during this diet had normal organ function restored after incremental amounts of choline were added back to the diet. Blood and urine were monitored for signs of toxicity and metabolite concentrations, and liver fat was assessed by using magnetic resonance imaging. RESULTS When deprived of dietary choline, 77% of men and 80% of postmenopausal women developed fatty liver or muscle damage, whereas only 44% of premenopausal women developed such signs of organ dysfunction. Moreover, 6 men developed these signs while consuming 550 mg choline x 70 kg(-1) x d(-1), the AI for choline. Folic acid supplementation did not alter the subjects' response. CONCLUSION Subject characteristics (eg, menopausal status) modulated the dietary requirement for choline, and a daily intake at the current AI was not sufficient to prevent organ dysfunction in 19 of the subjects.
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Affiliation(s)
- Leslie M Fischer
- Department of Nutrition, School of Public Health and School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7461, USA
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Jiráček J, Collinsová M, Rosenberg I, Buděšínský M, Protivínská E, Netušilová H, Garrow TA. S-alkylated homocysteine derivatives: new inhibitors of human betaine-homocysteine S-methyltransferase. J Med Chem 2006; 49:3982-9. [PMID: 16789755 PMCID: PMC2622432 DOI: 10.1021/jm050885v] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A series of S-alkylated derivatives of homocysteine were synthesized and characterized as inhibitors of human recombinant betaine-homocysteine S-methyltransferase (BHMT). Some of these compounds inhibit BHMT with IC50 values in the nanomolar range. BHMT is very sensitive to the structure of substituents on the sulfur atom of homocysteine. The S-carboxybutyl and S-carboxypentyl derivatives make the most potent inhibitors, and an additional sulfur atom in the alkyl chain is well tolerated. The respective (R,S)-5-(3-amino-3-carboxy-propylsulfanyl)-pentanoic, (R,S)-6-(3-amino-3-carboxy-propylsulfanyl)-hexanoic, and (R,S)-2-amino-4-(2-carboxymethylsulfanyl-ethylsulfanyl)-butyric acids are very potent inhibitors and are the strongest ever reported. We determined that (R,S)-5-(3-amino-3-carboxy-propylsulfanyl)-pentanoic acid displays competitive inhibition with respect to betaine binding with a Kappi of 12 nM. Some of these compounds are currently being tested in mice to study the influence of BHMT on the metabolism of sulfur amino acids in vivo.
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Affiliation(s)
- Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
- Corresponding authors. Tel +420220183441, fax +420220183571, e-mails ,
| | - Michaela Collinsová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Ivan Rosenberg
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
- Corresponding authors. Tel +420220183441, fax +420220183571, e-mails ,
| | - Miloš Buděšínský
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Eva Protivínská
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Hana Netušilová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Timothy A. Garrow
- Department of Food Science and Human Nutrition, University of Illinois, Urbana, Illinois 61801, USA
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