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Nakano SI, Sugimoto N. Model studies of the effects of intracellular crowding on nucleic acid interactions. MOLECULAR BIOSYSTEMS 2017; 13:32-41. [PMID: 27819369 DOI: 10.1039/c6mb00654j] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Molecular interactions and reactions in living cells occur with high concentrations of background molecules and ions. Many research studies have shown that intracellular molecules have characteristics different from those obtained using simple aqueous solutions. To better understand the behavior of biomolecules in intracellular environments, biophysical experiments were conducted under cell-mimicking conditions in a test tube. It has been shown that the molecular environments at the physiological level of macromolecular crowding, spatial confinement, water activity and dielectric constant, have significant effects on the interactions of DNA and RNA for hybridization, higher-order folding, and catalytic activity. The experimental approaches using in vitro model systems are useful to reveal the origin of the environmental effects and to bridge the gap between the behaviors of nucleic acids in vitro and in vivo. This paper highlights the model experiments used to evaluate the influences of intracellular environment on nucleic acid interactions.
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Affiliation(s)
- Shu-Ichi Nakano
- Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20, Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
| | - Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20, Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan. and Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20, Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan
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102
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Abstract
Volume is an essential characteristic of a cell, and this review describes the main methods of its measurement that have been used in the past several decades. The discussed methods include various implementations of light scattering, estimates based on one or two cell dimensions, surface scanning, fluorescence confocal and transmission slice-by-slice imaging, intracellular volume markers, displacement of extracellular solution, quantitative phase imaging, radioactive methods, and some others. Suitability of these methods to some typical samples and applications is discussed. © 2017 International Society for Advancement of Cytometry.
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Affiliation(s)
- Michael A Model
- Department of Biological Sciences, Kent State University, Kent, Ohio
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103
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Abstract
Osmosensory neurons are specialized cells activated by increases in blood osmolality to trigger thirst, secretion of the antidiuretic hormone vasopressin, and elevated sympathetic tone during dehydration. In addition to multiple extrinsic factors modulating their activity, osmosensory neurons are intrinsically osmosensitive, as they are activated by increased osmolality in the absence of neighboring cells or synaptic contacts. This intrinsic osmosensitivity is a mechanical process associated with osmolality-induced changes in cell volume. This review summarises recent findings revealing molecular mechanisms underlying the mechanical activation of osmosensory neurons and highlighting important roles of microtubules, actin, and mechanosensitive ion channels in this process.
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104
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The effect of substrate stiffness on cancer cell volume homeostasis. J Cell Physiol 2017; 233:1414-1423. [DOI: 10.1002/jcp.26026] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 05/22/2017] [Indexed: 12/30/2022]
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105
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Hui TH, Kwan KW, Chun Yip TT, Fong HW, Ngan KC, Yu M, Yao S, Wan Ngan AH, Lin Y. Regulating the Membrane Transport Activity and Death of Cells via Electroosmotic Manipulation. Biophys J 2017; 110:2769-2778. [PMID: 27332135 DOI: 10.1016/j.bpj.2016.05.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 05/03/2016] [Accepted: 05/09/2016] [Indexed: 11/26/2022] Open
Abstract
Although the volume of living cells has been known to heavily influence their behavior and fate, a method allowing us to control the cell size in a programmable manner is still lacking. Here, we develop a technique in which precise changes in the cellular volume can be conveniently introduced by varying the voltage applied across a Nafion membrane that separates the culture medium from a reservoir. It is found that, unlike sudden osmotic shocks, active ion transport across the membrane of leukemia K562 cells will not be triggered by a gradual change in the extracellular osmolarity. Furthermore, when subjected to the same applied voltage, different lung and nasopharyngeal epithelial cancer cells will undergo larger volumetric changes and have a 5-10% higher death rate compared to their normal counterparts. We show that such distinct response is largely caused by the overexpression of aquaporin-4 in tumor cells, with knockout of this water channel protein resulting in a markedly reduced change in the cellular volume. Finally, by taking into account the exchange of water/ion molecules across the Nafion film and the cell membrane, a theoretical model is also proposed to describe the voltage-induced size changes of cells, which explain our experimental observations very well.
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Affiliation(s)
- Tsz Hin Hui
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China; HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Shenzhen, Guangdong, China
| | - Kin Wah Kwan
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
| | | | - Hong Wai Fong
- Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong SAR, China
| | - Kai Cheong Ngan
- Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong SAR, China
| | - Miao Yu
- Bioengineering Graduate Program, Biomedical Engineering Division, Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Shuhuai Yao
- Bioengineering Graduate Program, Biomedical Engineering Division, Hong Kong University of Science and Technology, Hong Kong SAR, China; Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Alfonso Hin Wan Ngan
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China.
| | - Yuan Lin
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China; HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Shenzhen, Guangdong, China.
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106
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Di Lorenzo F, Billod JM, Martín-Santamaría S, Silipo A, Molinaro A. Gram-Negative Extremophile Lipopolysaccharides: Promising Source of Inspiration for a New Generation of Endotoxin Antagonists. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700113] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Flaviana Di Lorenzo
- Department of Chemical Sciences; University of Naples Federico II; via Cinthia 480126 80126 Naples Italy
| | - Jean-Marc Billod
- Department of Chemical and Physical Biology; CIB Centro de Investigaciones Biológicas; Ramiro de Maeztu 9 28040 Madrid Spain
| | - Sonsoles Martín-Santamaría
- Department of Chemical and Physical Biology; CIB Centro de Investigaciones Biológicas; Ramiro de Maeztu 9 28040 Madrid Spain
| | - Alba Silipo
- Department of Chemical Sciences; University of Naples Federico II; via Cinthia 480126 80126 Naples Italy
| | - Antonio Molinaro
- Department of Chemical Sciences; University of Naples Federico II; via Cinthia 480126 80126 Naples Italy
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107
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Cui MH, Suzuka SM, Branch NA, Ambadipudi K, Thangaswamy S, Acharya SA, Billett HH, Branch CA. Brain neurochemical and hemodynamic findings in the NY1DD mouse model of mild sickle cell disease. NMR IN BIOMEDICINE 2017; 30:e3692. [PMID: 28186661 DOI: 10.1002/nbm.3692] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Revised: 11/10/2016] [Accepted: 12/14/2016] [Indexed: 06/06/2023]
Abstract
To characterize the cerebral profile associated with sickle cell disease (SCD), we used in vivo proton MRI and MRS to quantify hemodynamics and neurochemicals in the thalamus of NY1DD mice, a mild model of SCD, and compared them with wild-type (WT) control mice. Compared with WT mice, NY1DD mice at steady state had elevated cerebral blood flow (CBF) and concentrations of N-acetylaspartate (NAA), glutamate (Glu), alanine, total creatine and N-acetylaspartylglutamate. Concentrations of glutathione (GSH) at steady state showed a negative correlation with BOLD signal change in response to 100% oxygen, a marker for oxidative stress, and mean diffusivity assessed using diffusion-tensor imaging, a marker for edematous inflammation. In NY1DD mice, elevated basal CBF was correlated negatively with [NAA], but positively with concentration of glutamine ([Gln]). Immediately after experimental hypoxia (at reoxygenation after 18 hours of 8% O2 ), concentrations of NAA, Glu, GSH, Gln and taurine (Tau) increased only in NY1DD mice. [NAA], [Glu], [GSH] and [Tau] all returned to baseline levels two weeks after the hypoxic episode. The altered neurochemical profile in the NY1DD mouse model of SCD at steady state and following experimental hypoxia/reoxygenation suggests a state of chronic oxidative stress leading to compensatory cerebral metabolic adjustments.
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Affiliation(s)
- Min-Hui Cui
- Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Radiology, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Sandra M Suzuka
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Nicholas A Branch
- Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Aerospace Engineering, Georgia Tech, Atlanta, GA, USA
| | - Kamalakar Ambadipudi
- Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Sangeetha Thangaswamy
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Seetharama A Acharya
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Medicine (Hematology), Albert Einstein College of Medicine, Bronx, New York, USA
| | - Henny H Billett
- Department of Medicine (Hematology), Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Craig A Branch
- Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Radiology, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York, USA
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108
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Alshalani A, Acker JP. Red blood cell membrane water permeability increases with length of ex vivo storage. Cryobiology 2017; 76:51-58. [PMID: 28456565 DOI: 10.1016/j.cryobiol.2017.04.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/14/2017] [Accepted: 04/13/2017] [Indexed: 10/19/2022]
Abstract
Water transport across the red blood cell (RBC) membrane is an essential cell function that needs to be preserved during ex vivo storage. Progressive biochemical depletion during storage can result in significant conformational and compositional changes to the membrane. Characterizing the changes to RBC water permeability can help in evaluating the quality of stored blood products and aid in the development of improved methods for the cryopreservation of red blood cells. This study aimed to characterize the water permeability (Lp), osmotically inactive fraction (b), and Arrhenius activation energy (Ea) at defined storage time-points throughout storage and to correlate the observed results with other in vitro RBC quality parameters. RBCs were collected from age- and sex-matched blood donors. A stopped flow spectrophotometer was used to determine Lp and b by monitoring changes in hemoglobin autofluorescence when RBCs were exposed to anisotonic solutions. Experimental values of Lp were characterized at three different temperatures (4, 20 and 37 °C) to determine the Ea. Results showed that Lp, b, and Ea of stored RBCs significantly increase by day 21 of storage. Degradation of the RBC membrane with length of storage was seen as an increase in hemolysis and supernatant potassium, and a decrease in deformability, mean corpuscular hemoglobin concentration and supernatant sodium. RBC osmotic characteristics were shown to change with storage and correlate with changes in RBC membrane quality metrics. Monitoring water parameters is a predictor of membrane damage and loss of membrane integrity in ex vivo stored RBCs.
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Affiliation(s)
- Abdulrahman Alshalani
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada; Department of Clinical Laboratory Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Jason P Acker
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada; Centre for Innovation, Canadian Blood Services, Edmonton, Alberta, Canada.
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109
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110
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Long term betaine supplementation regulates genes involved in lipid and cholesterol metabolism of two muscles from an obese pig breed. Meat Sci 2017; 124:25-33. [DOI: 10.1016/j.meatsci.2016.10.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 10/20/2016] [Accepted: 10/24/2016] [Indexed: 12/15/2022]
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111
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Evans GH, James LJ, Shirreffs SM, Maughan RJ. Optimizing the restoration and maintenance of fluid balance after exercise-induced dehydration. J Appl Physiol (1985) 2017; 122:945-951. [PMID: 28126906 DOI: 10.1152/japplphysiol.00745.2016] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 01/10/2017] [Accepted: 01/17/2017] [Indexed: 11/22/2022] Open
Abstract
Hypohydration, or a body water deficit, is a common occurrence in athletes and recreational exercisers following the completion of an exercise session. For those who will undertake a further exercise session that day, it is important to replace water losses to avoid beginning the next exercise session hypohydrated and the potential detrimental effects on performance that this may lead to. The aim of this review is to provide an overview of the research related to factors that may affect postexercise rehydration. Research in this area has focused on the volume of fluid to be ingested, the rate of fluid ingestion, and fluid composition. Volume replacement during recovery should exceed that lost during exercise to allow for ongoing water loss; however, ingestion of large volumes of plain water results in a prompt diuresis, effectively preventing longer-term maintenance of water balance. Addition of sodium to a rehydration solution is beneficial for maintenance of fluid balance due to its effect on extracellular fluid osmolality and volume. The addition of macronutrients such as carbohydrate and protein can promote maintenance of hydration by influencing absorption and distribution of ingested water, which in turn effects extracellular fluid osmolality and volume. Alcohol is commonly consumed in the postexercise period and may influence postexercise rehydration, as will the coingestion of food. Future research in this area should focus on providing information related to optimal rates of fluid ingestion, advisable solutions to ingest during different duration recovery periods, and confirmation of mechanistic explanations for the observations outlined.
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Affiliation(s)
- Gethin H Evans
- School of Healthcare Science, Manchester Metropolitan University, Manchester, United Kingdom;
| | - Lewis J James
- School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, Leicestershire, United Kingdom; and
| | - Susan M Shirreffs
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom
| | - Ronald J Maughan
- School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, Leicestershire, United Kingdom; and
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112
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Crude venom from nematocysts of Pelagia noctiluca (Cnidaria: Scyphozoa) elicits a sodium conductance in the plasma membrane of mammalian cells. Sci Rep 2017; 7:41065. [PMID: 28112211 PMCID: PMC5253680 DOI: 10.1038/srep41065] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 12/14/2016] [Indexed: 01/25/2023] Open
Abstract
Cnidarians may negatively impact human activities and public health but concomitantly their venom represents a rich source of bioactive substances. Pelagia noctiluca is the most venomous and abundant jellyfish of the Mediterranean Sea and possesses a venom with hemolytic and cytolytic activity for which the mechanism is largely unknown. Here we show that exposure of mammalian cells to crude venom from the nematocysts of P. noctiluca profoundly alters the ion conductance of the plasma membrane, therefore affecting homeostatic functions such as the regulation and maintenance of cellular volume. Venom-treated cells exhibited a large, inwardly rectifying current mainly due to permeation of Na+ and Cl−, sensitive to amiloride and completely abrogated following harsh thermal treatment of crude venom extract. Curiously, the plasma membrane conductance of Ca2+ and K+ was not affected. Current-inducing activity was also observed following delivery of venom to the cytosolic side of the plasma membrane, consistent with a pore-forming mechanism. Venom-induced NaCl influx followed by water and consequent cell swelling most likely underlie the hemolytic and cytolytic activity of P. noctiluca venom. The present study underscores unique properties of P. noctiluca venom and provides essential information for a possible use of its active compounds and treatment of envenomation.
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113
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Steininger PA, Strasser EF, Ziehe B, Eckstein R, Rauh M. Change of the metabolomic profile during short-term mononuclear cell storage. Vox Sang 2017; 112:163-172. [PMID: 28052337 DOI: 10.1111/vox.12482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 10/05/2016] [Accepted: 10/31/2016] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND OBJECTIVES Short-term storage of leukapheresis products used for immunotherapeutic mononuclear cell (MNC) products is a frequent event. The analysis of time-related metabolic patterns enables the characterization of storage-related effects in MNCs and the hypothesis-based optimization of the MNC medium. MATERIALS AND METHODS The MNC products from seven leukapheresis procedures were stored within a closed bag system for 48 h. Concentrations of amino acids, biogenic amines, phospho- and sphingolipids and hexoses in the medium were measured by targeted metabolomics. The viability of MNC subpopulations was assayed by Annexin V (AnV) and JC-1 staining. RESULTS Glucose depletion and a significant change of the acylcarnitine profile are early events within the first 24 h of storage. In contrast, for most amino acids, the maximum increase was observed at 48 h of storage as mirrored by an increase in the amino acid levels by a mean factor of 1·2 (1·3, 2·0) after 6 h (24 h, 48 h, respectively). This was except for the concentrations of glutamine and lysine, which did not change significantly. The taurine concentration showed a twofold increase within the first 24 h and remained constant thereafter. The steepest increase in AnV+ and 7-AAD+ CD4+ T cells was found between 24 and 48 h. CONCLUSION The time-course of apoptosis and metabolic patterns in the MNC products demonstrate that 24 h of storage is a decisive time-point, as afterwards key metabolic pathways showed nonlinear detrimental changes. Optimization of storage by supplementation of specific substrates demands therefore an early intervention.
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Affiliation(s)
- P A Steininger
- Department of Transfusion Medicine and Haemostaseology, University Hospital of Erlangen, Erlangen, Germany
| | - E F Strasser
- Department of Transfusion Medicine and Haemostaseology, University Hospital of Erlangen, Erlangen, Germany
| | - B Ziehe
- Department of Transfusion Medicine and Haemostaseology, University Hospital of Erlangen, Erlangen, Germany
| | - R Eckstein
- Department of Transfusion Medicine and Haemostaseology, University Hospital of Erlangen, Erlangen, Germany
| | - M Rauh
- Department of Paediatrics and Adolescent Medicine, University Hospital of Erlangen, Erlangen, Germany
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Chen SL, Deng YY, Wang QS, Han YL, Jiang WQ, Fang M, Hu B, Wu ZX, Huang LQ, Zeng HK. Hypertonic saline protects brain endothelial cells against hypoxia correlated to the levels of epidermal growth factor receptor and interleukin-1β. Medicine (Baltimore) 2017; 96:e5786. [PMID: 28072729 PMCID: PMC5228689 DOI: 10.1097/md.0000000000005786] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVE The aim of this study was to verify the protective effect of hypertonic saline (HS) on brain endothelial cells under hypoxic conditions and the relevant underlying mechanism. METHODS bEnd.3 cells were treated with oxygen-glucose deprivation (OGD)-induced injury. To measure HS performance, cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt assay, and cell apoptosis was assessed by flow cytometry and Terminal deoxynucleotidyl transferase UTP nick-end labeling staining. RNA-seq was performed to assess the expression profiles and screen the candidate genes that participated in OGD-induced injury and the HS protective effect. Quantitative real-time polymerase chain reaction (qPCR) and western blot analysis were used to confirm the expression of candidate genes, and enzyme-linked immunosorbent assay was used to measure the level of interleukin (IL)-1β. Overexpression analyses were performed to confirm the functions of the differentially expressed genes. RESULTS HS with a concentration of 40 mmol/L NaCl had an obvious protective effect on bEnd.3 cells after OGD-induced injury, resulting in increased cell viability and a smaller percentage of apoptotic cells. According to the RNA-seq results, epidermal growth factor receptor (EGFR) was chosen as the differentially expressed gene target in this study. The qPCR and western blot analyses further confirmed that the levels of EGFR/phosphorylated epidermal growth factor receptor and IL-1β were enhanced after OGD-induced injury, but attenuated after treatment with 40 mmol/L of NaCl HS. Overexpressed EGFR reversed the protective effect of HS that caused low viability and high rates of apoptosis in cells. CONCLUSION HS can protect endothelial cells against OGD-induced injury, but is affected by the expression of EGFR/p-EGFR and IL-1β.
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Affiliation(s)
- Sheng-Long Chen
- Graduate School, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, PR China
- Department of Emergency and Critical Care Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences,106 Zhongshan Er Road, Guangzhou 510080, PR China
| | - Yi-Yu Deng
- Department of Emergency and Critical Care Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences,106 Zhongshan Er Road, Guangzhou 510080, PR China
| | - Qiao-Sheng Wang
- Department of Critical Care Medicine, The First Affiliated Hospital, University of South China, Hengyang, Hunan Province, PR China
| | - Yong-Li Han
- Department of Emergency and Critical Care Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences,106 Zhongshan Er Road, Guangzhou 510080, PR China
| | - Wen-Qiang Jiang
- Department of Emergency and Critical Care Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences,106 Zhongshan Er Road, Guangzhou 510080, PR China
| | - Ming Fang
- Department of Emergency and Critical Care Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences,106 Zhongshan Er Road, Guangzhou 510080, PR China
| | - Bei Hu
- Department of Emergency and Critical Care Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences,106 Zhongshan Er Road, Guangzhou 510080, PR China
| | - Zhi-Xin Wu
- Graduate School, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, PR China
| | - Lin-Qiang Huang
- Department of Emergency and Critical Care Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences,106 Zhongshan Er Road, Guangzhou 510080, PR China
| | - Hong-Ke Zeng
- Graduate School, Southern Medical University, 1838 North Guangzhou Avenue, Guangzhou 510515, PR China
- Department of Emergency and Critical Care Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences,106 Zhongshan Er Road, Guangzhou 510080, PR China
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115
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Mechanism of the cytotoxic effect of l-amino acid oxidase isolated from Bothrops alternatus snake venom. Int J Biol Macromol 2016; 92:329-337. [DOI: 10.1016/j.ijbiomac.2016.07.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 07/04/2016] [Accepted: 07/05/2016] [Indexed: 01/05/2023]
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116
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Zhang J, Gao G, Begum G, Wang J, Khanna AR, Shmukler BE, Daubner GM, de los Heros P, Davies P, Varghese J, Bhuiyan MIH, Duan J, Zhang J, Duran D, Alper SL, Sun D, Elledge SJ, Alessi DR, Kahle KT. Functional kinomics establishes a critical node of volume-sensitive cation-Cl - cotransporter regulation in the mammalian brain. Sci Rep 2016; 6:35986. [PMID: 27782176 PMCID: PMC5080614 DOI: 10.1038/srep35986] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 10/04/2016] [Indexed: 02/08/2023] Open
Abstract
Cell volume homeostasis requires the dynamically regulated transport of ions across the plasmalemma. While the ensemble of ion transport proteins involved in cell volume regulation is well established, the molecular coordinators of their activities remain poorly characterized. We utilized a functional kinomics approach including a kinome-wide siRNA-phosphoproteomic screen, a high-content kinase inhibitor screen, and a kinase trapping-Orbitrap mass spectroscopy screen to systematically identify essential kinase regulators of KCC3 Thr991/Thr1048 phosphorylation - a key signaling event in cell swelling-induced regulatory volume decrease (RVD). In the mammalian brain, we found the Cl--sensitive WNK3-SPAK kinase complex, required for cell shrinkage-induced regulatory volume decrease (RVI) via the stimulatory phosphorylation of NKCC1 (Thr203/Thr207/Thr212), is also essential for the inhibitory phosphorylation of KCC3 (Thr991/Thr1048). This is mediated in vivo by an interaction between the CCT domain in SPAK and RFXV/I domains in WNK3 and NKCC1/KCC3. Accordingly, genetic or pharmacologic WNK3-SPAK inhibition prevents cell swelling in response to osmotic stress and ameliorates post-ischemic brain swelling through a simultaneous inhibition of NKCC1-mediated Cl- uptake and stimulation of KCC3-mediated Cl- extrusion. We conclude that WNK3-SPAK is an integral component of the long-sought "Cl-/volume-sensitive kinase" of the cation-Cl- cotransporters, and functions as a molecular rheostat of cell volume in the mammalian brain.
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Affiliation(s)
- Jinwei Zhang
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
- Departments of Neurosurgery and Pediatrics, Yale School of Medicine, New Haven, CT 06511 USA
| | - Geng Gao
- Division of Genetics, Brigham and Women’s Hospital, Boston, MA 02115 USA
| | - Gulnaz Begum
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Jinhua Wang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Department of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, 250 Longwood Ave, SGM 628, Boston, MA 02115, USA
| | - Arjun R. Khanna
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA 02114 USA
| | - Boris E. Shmukler
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA -022154 USA
- Department of Medicine, Harvard Medical School, Boston, MA -022154, USA
| | - Gerrit M. Daubner
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Paola de los Heros
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Paul Davies
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Joby Varghese
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | | | - Jinjing Duan
- Departments of Neurosurgery and Pediatrics, Yale School of Medicine, New Haven, CT 06511 USA
- Department of Cardiology, Howard Hughes Medical Institute, Boston Children’s Hospital, Boston, Massachusetts 02115, USA
| | - Jin Zhang
- Department of Cardiology, Howard Hughes Medical Institute, Boston Children’s Hospital, Boston, Massachusetts 02115, USA
| | - Daniel Duran
- Departments of Neurosurgery and Pediatrics, Yale School of Medicine, New Haven, CT 06511 USA
| | - Seth L. Alper
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA -022154 USA
- Department of Medicine, Harvard Medical School, Boston, MA -022154, USA
| | - Dandan Sun
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Veterans Affairs Pittsburgh Health Care System, Geriatric Research, Educational and Clinical Center, Pittsburgh, PA, USA
| | - Stephen J. Elledge
- Department of Genetics, Harvard University Medical School, Howard Hughes Medical Institute, Boston, Massachusetts 02115 USA
| | - Dario R. Alessi
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Kristopher T. Kahle
- Departments of Pediatrics and Cellular & Molecular Physiology; Interdepartmental Neuroscience Program; and Centers for Mendelian Genomics, Yale School of Medicine, New Haven, CT 06511 USA
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Abstract
Alterations at the level of plasma membrane are reported to play an important role in cellular senescence. The present study was undertaken to correlate cellular senescence, membrane transport processes and organismal aging. To achieve this objective activities of membrane linked Na+/K + ATPase (NKA), Na+/H+ exchanger (NHE) and correlation with membrane hydrxyperoxide level, sialic acid content and membrane protein oxidation was studied in density-gradient fractionated young and old erythrocytes from 4 and 24 month old Wistar rats. The results reveal that cellular aging within the tissue is associated with significant decrease in activities of NKA and NHE of senescent erythrocytes in comparison to younger cell population of same age group. The result shows that impaired ion homeostasis due to altered membrane transporters including functional and compositional changes may be one of the reasons responsible behind rat erythrocyte aging.
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Affiliation(s)
- Sandeep Singh
- a Department of Biochemistry , University of Allahabad , Allahabad , India
| | | | - Syed Ibrahim Rizvi
- a Department of Biochemistry , University of Allahabad , Allahabad , India
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118
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Saleh AF, Fellows MD, Ying L, Gooderham NJ, Priestley CC. The Lack of Mutagenic Potential of a Guanine-Rich Triplex Forming Oligonucleotide in Physiological Conditions. Toxicol Sci 2016; 155:101-111. [PMID: 27660205 DOI: 10.1093/toxsci/kfw179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Triplex forming oligonucleotides (TFOs) bind in the major groove of DNA duplex in a sequence-specific manner imparted by Hoogsteen hydrogen bonds. There have been several reports demonstrating the ability of guanine-rich TFOs to induce targeted mutagenesis on an exogenous plasmid or an endogenous chromosomal locus. In particular, a 30mer guanine-rich triplex forming oligonucleotide, AG30, optimally designed to target the supFG1 reporter gene was reported to be mutagenic in the absence of DNA reactive agents in cultured cells and in vivo Here, we investigated the mutagenic potential of AG30 using the supFG1 shuttle vector forward mutation assay under physiological conditions. We also assessed the triplex binding potential of AG30 alongside cytotoxic and mutagenic assessment. In a cell free condition, AG30 was able to bind its polypurine target site in the supFG1 gene in the absence of potassium chloride and also aligned with a 5-fold increase in the mutant frequency when AG30 was pre-incubated with the supFG1 plasmid in the absence of potassium prior to transfection into COS-7 cells. However, when we analyzed triplex formation of AG30 and the supFG1 target duplex at physiological potassium levels, triplex formation was inhibited due to the formation of competing secondary structures. Subsequent assessment of mutant frequency under physiological conditions, by pre-transfecting COS-7 cells with the supFG1 plasmid prior to AG30 treatment led to a very small increase (1.4-fold) in the mutant frequency. Transfection of cells with even higher concentrations of AG30 did result in an elevated mutagenic response but this was also seen with a scrambled sequence, and was therefore considered unlikely to be biologically relevant as an associated increase in cytotoxicity was also apparent. Our findings also provide further assurance on the low potential of triplex-mediated mutation as a consequence of unintentional genomic DNA binding by therapeutic antisense oligonucleotides.
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Affiliation(s)
- Amer F Saleh
- Genetic Toxicology, Drug Safety and Metabolism, AstraZeneca, Macclesfield, Cheshire, United Kingdom
| | - Mick D Fellows
- Genetic Toxicology, Drug Safety and Metabolism, AstraZeneca, Macclesfield, Cheshire, United Kingdom
| | - Liming Ying
- Molecular medicine, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | | | - Catherine C Priestley
- Genetic Toxicology, Drug Safety and Metabolism, AstraZeneca, Macclesfield, Cheshire, United Kingdom;
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119
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Yu Y, Ye L, Li YG, Burkin DJ, Duan DD. Heart-specific overexpression of the human short CLC-3 chloride channel isoform limits myocardial ischemia-induced ERP and QT prolongation. Int J Cardiol 2016; 214:218-24. [PMID: 27064645 PMCID: PMC4862918 DOI: 10.1016/j.ijcard.2016.03.191] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 03/16/2016] [Accepted: 03/26/2016] [Indexed: 10/22/2022]
Abstract
INTRODUCTION Ischemia causes myocardial infarction and arrhythmias. Up-regulation of cardiac CLC-3 chloride channels is important for ischemic preconditioning-induced second-window protection against myocardial infarction. But its consequences in ischemia-induced electrical remodeling are still unknown. METHODS The recently-characterized heart-specific overexpression of human short CLC-3 isoform (hsCLC-3(OE)) mice was used to study the effects of CLC-3 up-regulation on cardiac electrophysiology under ischemia/reperfusion conditions. In vivo surface electrocardiography (ECG) and intracardiac electrophysiology (ICEP) were used to compare the electrophysiological properties of age-matched wild-type (Clcn3(+/+)) and hsCLC-3(OE) mice under control and myocardial ischemia-reperfusion conditions. RESULTS QT and QTc intervals of hsCLC-3(OE) mice were significantly shorter than those of Clcn3(+/+) mice under control, ischemia and reperfusion conditions. In the ICEP, ventricular effective refractory period (VERP) of hsCLC-3(OE) mice (26.7±1.7ms, n=6) was significantly shorter than that of Clcn3(+/+) mice (36.9±2.8ms, n=8, P<0.05). Under ischemia condition, both VERP (19.8±1.3ms) and atrial effective refractory period (AERP, 34.8±2.5ms) of hsCLC-3(OE) mice were significantly shorter than those of Clcn3(+/+) mice (35.2±3.0ms and 45.8±1.6ms, P<0.01, respectively). Wenckebach atrioventricular nodal block point (AVBP, 91.13±4.08ms) and 2:1 AVBP (71.3±3.8ms) of hsCLC-3(OE) mice were significantly shorter than those of Clcn3(+/+) mice (102.0±2.0ms and 84.1±2.8ms, P<0.05, respectively). However, no differences of ICEP parameters between hsCLC-3(OE) and Clcn3(+/+) mice were observed under reperfusion conditions. CONCLUSION Heart-specific overexpression of hsCLC-3 limited the ischemia-induced QT and ERP prolongation and postponed the advancements of Wenckebach and 2:1 AVBP. CLC-3 up-regulation may serve as an important adaptive mechanism against myocardial ischemia.
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Affiliation(s)
- Ying Yu
- Department of Cardiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China; Laboratory of Cardiovascular Phenomics, University of Nevada School of Medicine, Reno, NV 89557-0318, USA; Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557-0318, USA
| | - Linda Ye
- Laboratory of Cardiovascular Phenomics, University of Nevada School of Medicine, Reno, NV 89557-0318, USA; Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557-0318, USA
| | - Yi-Gang Li
- Department of Cardiology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
| | - Dean J Burkin
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557-0318, USA
| | - Dayue Darrel Duan
- Laboratory of Cardiovascular Phenomics, University of Nevada School of Medicine, Reno, NV 89557-0318, USA; Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557-0318, USA.
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120
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Pasantes-Morales H. Channels and Volume Changes in the Life and Death of the Cell. Mol Pharmacol 2016; 90:358-70. [PMID: 27358231 DOI: 10.1124/mol.116.104158] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/22/2016] [Indexed: 12/11/2022] Open
Abstract
Volume changes deviating from original cell volume represent a major challenge for cellular homeostasis. Cell volume may be altered either by variations in the external osmolarity or by disturbances in the transmembrane ion gradients that generate an osmotic imbalance. Cells respond to anisotonicity-induced volume changes by active regulatory mechanisms that modify the intracellular/extracellular concentrations of K(+), Cl(-), Na(+), and organic osmolytes in the direction necessary to reestablish the osmotic equilibrium. Corrective osmolyte fluxes permeate across channels that have a relevant role in cell volume regulation. Channels also participate as causal actors in necrotic swelling and apoptotic volume decrease. This is an overview of the types of channels involved in either corrective or pathologic changes in cell volume. The review also underlines the contribution of transient receptor potential (TRP) channels, notably TRPV4, in volume regulation after swelling and describes the role of other TRPs in volume changes linked to apoptosis and necrosis. Lastly we discuss findings showing that multimers derived from LRRC8A (leucine-rich repeat containing 8A) gene are structural components of the volume-regulated Cl(-) channel (VRAC), and we underline the intriguing possibility that different heteromer combinations comprise channels with different intrinsic properties that allow permeation of the heterogenous group of molecules acting as organic osmolytes.
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Affiliation(s)
- Herminia Pasantes-Morales
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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121
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Deeb RS, Walters MS, Strulovici-Barel Y, Chen Q, Gross SS, Crystal RG. Smoking-Associated Disordering of the Airway Basal Stem/Progenitor Cell Metabotype. Am J Respir Cell Mol Biol 2016; 54:231-40. [PMID: 26161876 DOI: 10.1165/rcmb.2015-0055oc] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The airway epithelium is a complex pseudostratified multicellular layer lining the tracheobronchial tree, functioning as the primary defense against inhaled environmental contaminants. The major cell types of the airway epithelium include basal, intermediate columnar, ciliated, and secretory. Basal cells (BCs) are the proliferating stem/progenitor population that differentiate into the other specialized cell types of the airway epithelium during normal turnover and repair. Given that cigarette smoke delivers thousands of xenobiotics and high levels of reactive molecules to the lung epithelial surface, we hypothesized that cigarette smoke broadly perturbs BC metabolism. To test this hypothesis, primary airway BCs were isolated from healthy nonsmokers (n = 11) and healthy smokers (n = 7) and assessed by global metabolic profiling by liquid chromatography-mass spectrometry. The analysis identified 52 significant metabolites in BCs differentially expressed between smokers and nonsmokers (P < 0.05). These changes included metabolites associated with redox pathways, energy production, and inflammatory processes. Notably, BCs from smokers exhibited altered levels of the key enzyme cofactors/substrates nicotinamide adenine dinucleotide, flavin adenine dinucleotide, acetyl coenzyme A, and membrane phospholipid levels. Consistent with the high burden of oxidants in cigarette smoke, glutathione levels were diminished, whereas 3-nitrotyrosine levels were increased, suggesting that protection of airway epithelial cells against oxidative and nitrosative stress is significantly compromised in smoker BCs. It is likely that this altered metabotype is a reflection of, and likely contributes to, the disordered biology of airway BCs consequent to the stress cigarette smoking puts on the airway epithelium.
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Affiliation(s)
| | | | | | - Qiuying Chen
- 2 Pharmacology, Weill Cornell Medical College, New York, New York
| | - Steven S Gross
- 2 Pharmacology, Weill Cornell Medical College, New York, New York
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122
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Gui L, Zhang P, Liang X, Su M, Wu D, Zhang J. Adaptive responses to osmotic stress in kidney-derived cell lines from Scatophagus argus , a euryhaline fish. Gene 2016; 583:134-140. [DOI: 10.1016/j.gene.2016.02.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 12/06/2015] [Accepted: 02/10/2016] [Indexed: 10/22/2022]
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123
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Zhou X, Naguro I, Ichijo H, Watanabe K. Mitogen-activated protein kinases as key players in osmotic stress signaling. Biochim Biophys Acta Gen Subj 2016; 1860:2037-52. [PMID: 27261090 DOI: 10.1016/j.bbagen.2016.05.032] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/21/2016] [Indexed: 11/29/2022]
Abstract
BACKGROUND Osmotic stress arises from the difference between intracellular and extracellular osmolality. It induces cell swelling or shrinkage as a consequence of water influx or efflux, which threatens cellular activities. Mitogen-activated protein kinases (MAPKs) play central roles in signaling pathways in osmotic stress responses, including the regulation of intracellular levels of inorganic ions and organic osmolytes. SCOPE OF REVIEW The present review summarizes the cellular osmotic stress response and the function and regulation of the vertebrate MAPK signaling pathways involved. We also describe recent findings regarding apoptosis signal-regulating kinase 3 (ASK3), a MAP3K member, to demonstrate its regulatory effects on signaling molecules beyond MAPKs. MAJOR CONCLUSIONS MAPKs are rapidly activated by osmotic stress and have diverse roles, such as cell volume regulation, gene expression, and cell survival/death. There is significant cell type specificity in the function and regulation of MAPKs. Based on its activity change during osmotic stress and its regulation of the WNK1-SPAK/OSR1 pathway, ASK3 is expected to play important roles in osmosensing mechanisms and cellular functions related to osmoregulation. GENERAL SIGNIFICANCE MAPKs are essential for various cellular responses to osmotic stress; thus, the identification of the upstream regulators of MAPK pathways will provide valuable clues regarding the cellular osmosensing mechanism, which remains elusive in mammals. The elucidation of in vivo MAPK functions is also important because osmotic stress in physiological and pathophysiological conditions often results from changes in the intracellular osmolality. These studies potentially contribute to the establishment of therapeutic strategies against diseases that accompany osmotic perturbation.
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Affiliation(s)
- Xiangyu Zhou
- Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Isao Naguro
- Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hidenori Ichijo
- Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kengo Watanabe
- Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Hirani N, Westenberg M, Seed PT, Petalcorin MIR, Dolphin CT. C. elegans flavin-containing monooxygenase-4 is essential for osmoregulation in hypotonic stress. Biol Open 2016; 5:537-49. [PMID: 27010030 PMCID: PMC4874355 DOI: 10.1242/bio.017400] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Studies in Caenorhabditis elegans have revealed osmoregulatory systems engaged when worms experience hypertonic conditions, but less is known about measures employed when faced with hypotonic stress. Inactivation of fmo-4, which encodes flavin-containing monooxygenase-4, results in dramatic hypoosmotic hypersensitivity; worms are unable to prevent overwhelming water influx and swell rapidly, finally rupturing due to high internal hydrostatic pressure. fmo-4 is expressed prominently in hypodermis, duct and pore cells but is excluded from the excretory cell. Thus, FMO-4 plays a crucial osmoregulatory role by promoting clearance of excess water that enters during hypotonicity, perhaps by synthesizing an osmolyte that acts to establish an osmotic gradient from excretory cell to duct and pore cells. C. elegans FMO-4 contains a C-terminal extension conserved in all nematode FMO-4s. The coincidently numbered human FMO4 also contains an extended C-terminus with features similar to those of FMO-4. Although these shared sequence characteristics suggest potential orthology, human FMO4 was unable to rescue the fmo-4 osmoregulatory defect. Intriguingly, however, mammalian FMO4 is expressed predominantly in the kidney - an appropriate site if it too is, or once was, involved in osmoregulation.
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Affiliation(s)
- Nisha Hirani
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
| | - Marcel Westenberg
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
| | - Paul T Seed
- Division of Women's Health, King's College London, St Thomas' Hospital, London SE1 7EH, UK
| | - Mark I R Petalcorin
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
| | - Colin T Dolphin
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
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125
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Robinson JL, Bertolo RF. The Pediatric Methionine Requirement Should Incorporate Remethylation Potential and Transmethylation Demands. Adv Nutr 2016; 7:523-34. [PMID: 27184279 PMCID: PMC4863267 DOI: 10.3945/an.115.010843] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The metabolic demand for methionine is great in neonates. Indeed, methionine is the only indispensable sulfur amino acid and is required not only for protein synthesis and growth but is also partitioned to a greater extent to transsulfuration for cysteine and taurine synthesis and to >50 transmethylation reactions that serve to methylate DNA and synthesize metabolites, including creatine and phosphatidylcholine. Therefore, the pediatric methionine requirement must accommodate the demands of rapid protein turnover as well as vast nonprotein demands. Because cysteine spares the methionine requirement, it is likely that the dietary provision of transmethylation products can also feasibly spare methionine. However, understanding the requirement of methionine is further complicated because demethylated methionine can be remethylated by the dietary methyl donors folate and betaine (derived from choline). Intakes of dietary methyl donors are highly variable, which is of particular concern for newborns. It has been demonstrated that many populations have enhanced requirements for these nutrients, and nutrient fortification may exacerbate this phenomenon by selecting phenotypes that increase methyl requirements. Moreover, higher transmethylation rates can limit methyl supply and affect other transmethylation reactions as well as protein synthesis. Therefore, careful investigations are needed to determine how remethylation and transmethylation contribute to the methionine requirement. The purpose of this review is to support our hypothesis that dietary methyl donors and consumers can drive methionine availability for protein synthesis and transmethylation reactions. We argue that nutritional strategies in neonates need to ensure that methionine is available to meet requirements for growth as well as for transmethylation products.
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Affiliation(s)
| | - Robert F Bertolo
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
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126
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Choline Supplementation With a Structured Lipid in Children With Cystic Fibrosis: A Randomized Placebo-Controlled Trial. J Pediatr Gastroenterol Nutr 2016; 62:618-26. [PMID: 26465792 PMCID: PMC4805439 DOI: 10.1097/mpg.0000000000001004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Choline depletion is seen in cystic fibrosis (CF) and pancreatic insufficiency in spite of enzyme treatment and may result in liver, fatty acid, and muscle abnormalities. This study evaluated the efficacy and safety of an easily absorbed choline-rich structured lipid (LYM-X-SORB™ [LXS]) to improve choline status. METHODS Children with CF and pancreatic insufficiency were randomized to LXS or placebo in a 12-month double blind trial. Dietary choline intake, plasma cholines, plasma and fecal phospholipids, coefficient of fat absorption, pulmonary function, growth status, body composition, and safety measures were assessed. Magnetic resonance spectroscopy for calf muscle choline and liver fat were assessed in a subgroup and compared with a healthy comparison group matched for age, sex, and body size. RESULTS A total of 110 subjects were enrolled (age 10.4 ± 3.0 years). Baseline dietary choline, 88% recommended, increased 3-fold in the LXS group. Plasma choline, betaine, and dimethylglycine increased in the LXS but not placebo (P = 0.007). Plasma lysophosphatidylcholine and phosphatidylcholine increased, and fecal phosphatidylcholine/phosphatidylethanolamine ratio decreased (P ≤ 0.05) in LXS only, accompanied by a 6% coefficient of fat absorption increase (P = 0.001). Children with CF had higher liver fat than healthy children and depleted calf muscle choline at baseline. Muscle choline concentration increased in LXS and was associated with improvement in plasma choline status. No relevant changes in safety measures were evident. CONCLUSIONS LXS had improved choline intake, plasma choline status, and muscle choline stores compared with placebo group. The choline-rich supplement was safe, accepted by participants, and improved choline status in children with CF.
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127
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Meister CB, Kutianski FAT, Carstens LC, Andrade SLF, Rodacki ALF, Souza RMD. Effects of two programs of metabolic resistance training on strength and hypertrophy. FISIOTERAPIA EM MOVIMENTO 2016. [DOI: 10.1590/0103-5150.029.001.ao16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Abstract Introduction: The effects of low intensity resistance training combined with vascular occlusion have been investigated by several studies. Similar results on strength and hypertrophy have been observed when such method was compared to high intensity protocols. However, due to the specific apparatus needed to apply vascular occlusion (ex.: Kaatsu) on some exercises, alternative forms of metabolic training might be used. In the present study, an isometric contraction was performed within each concentric-eccentric transition phase, for every repetition, to elicit metabolic stress. Objective: The aim of the present study was to analyze the effects of two resistance training protocols with metabolic characteristics on strength (1MR), circumference (CIRC) and muscle thickness (measured with ultrasonography [MT]). Subjective perception of discomfort was also recorded with an analogical-visual pain scale (AVP). Methods: Twelve young, healthy men were trained with two different methods during 10 weeks. The right limb was trained with an isometric contraction within each concentric-eccentric transition phases for every repetition (ISO) whereas the left limb was trained with a pneumatic cuff to apply vascular occlusion (OC) on the knee extensor muscles. Both methods were trained at 20% 1MR. Results: It was observed increases on medial tight CIRC, proximal MT, medial MT, distal MT and 1MR, with no difference between both methods. The perception of discomfort was greater for ISO at the end of the third set and lower than reported by OC, at the beginning and end of the training program. Conclusions: Both protocols produced similar gains on strength and hypertrophy. The advantages of training with low loads are important to elderly or rehabilitation training programs. Other studies that compare this method with conventional resistance training are warranted.
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128
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Changes in Methionine Metabolism and Histone H3 Trimethylation Are Linked to Mitochondrial Defects in Multiple Sclerosis. J Neurosci 2016; 35:15170-86. [PMID: 26558787 DOI: 10.1523/jneurosci.4349-14.2015] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Mitochondrial changes, including decreased expression of electron transport chain subunit genes and impaired energetic, have been reported in multiple sclerosis (MS), but the mechanisms involved in these changes are not clear. To determine whether epigenetic mechanisms are involved, we measured the concentrations of methionine metabolites by liquid chromatography tandem mass spectrometry, histone H3 methylation patterns, and markers of mitochondrial respiration in gray matter from postmortem MS and control cortical samples. We found decreases in respiratory markers as well as decreased concentrations of the methionine metabolites S-adenosylmethionine, betaine, and cystathionine in MS gray matter. We also found expression of the enzyme betaine homocysteine methyltransferase in cortical neurons. This enzyme catalyzes the remethylation of homocysteine to methionine, with betaine as the methyl donor, and has previously been thought to be restricted to liver and kidney in the adult human. Decreases in the concentration of the methyl donor betaine were correlated with decreases in histone H3 trimethylation (H3K4me3) in NeuN+ neuronal nuclei in MS cortex compared with controls. Mechanistic studies demonstrated that H3K4me3 levels and mitochondrial respiration were reduced in SH-SY5Y cells after exposure to the nitric oxide donor sodium nitroprusside, and betaine was able to rescue H3K4me3 levels and respiratory capacity in these cells. Chromatin immunoprecipitation experiments showed that betaine regulates metabolic genes in human SH-SY5Y neuroblastoma cells. These data suggest that changes to methionine metabolism may be mechanistically linked to changes in neuronal energetics in MS cortex. SIGNIFICANCE STATEMENT For decades, it has been observed that vitamin B12 deficiency and multiple sclerosis (MS) share certain pathological changes, including conduction disturbances. In the present study, we have found that vitamin B12-dependent methionine metabolism is dysregulated in the MS brain. We found that concentrations of the methyl donor betaine are decreased in MS cortex and are correlated with reduced levels of the histone H3 methyl mark H3K4me3 in neurons. Cell culture and chromatin immunoprecipitation-seq data suggest that these changes may lead to defects in mitochondria and impact neuronal energetics. These data have uncovered a novel pathway linking methionine metabolism with mitochondrial respiration and have important implications for understanding mechanisms involved in neurodegeneration in MS.
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Petracca M, Fleysher L, Oesingmann N, Inglese M. Sodium MRI of multiple sclerosis. NMR IN BIOMEDICINE 2016; 29:153-61. [PMID: 25851455 PMCID: PMC5771413 DOI: 10.1002/nbm.3289] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 05/11/2023]
Abstract
Multiple sclerosis (MS) is the most common cause of non-traumatic disability in young adults. The mechanisms underlying neurodegeneration and disease progression are poorly understood, in part as a result of the lack of non-invasive methods to measure and monitor neurodegeneration in vivo. Sodium MRI is a topic of increasing interest in MS research as it allows the metabolic characterization of brain tissue in vivo, and integration with the structural information provided by (1)H MRI, helping in the exploration of pathogenetic mechanisms and possibly offering insights into disease progression and monitoring of treatment outcomes. We present an up-to-date review of the sodium MRI application in MS organized into four main sections: (i) biological and pathogenetic role of sodium; (ii) brief overview of sodium imaging techniques; (iii) results of sodium MRI application in clinical studies; and (iv) future perspectives.
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Affiliation(s)
- Maria Petracca
- Department of Neurology, Icahn School of Medicine, Mount Sinai, New York, USA
- Department of Neuroscience, Federico II University, Naples, Italy
| | - Lazar Fleysher
- Department of Radiology, Icahn School of Medicine, Mount Sinai, New York, USA
| | | | - Matilde Inglese
- Department of Neurology, Icahn School of Medicine, Mount Sinai, New York, USA
- Department of Radiology, Icahn School of Medicine, Mount Sinai, New York, USA
- Department of Neuroscience, Icahn School of Medicine, Mount Sinai, New York, USA
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Abstract
Metal ions are essential cofactors for the structure and functions of nucleic acids. Yet, the early discovery in the 70s of the crucial role of Mg(2+) in stabilizing tRNA structures has occulted for a long time the importance of monovalent cations. Renewed interest in these ions was brought in the late 90s by the discovery of specific potassium metal ions in the core of a group I intron. Their importance in nucleic acid folding and catalytic activity is now well established. However, detection of K(+) and Na(+) ions is notoriously problematic and the question about their specificity is recurrent. Here we review the different methods that can be used to detect K(+) and Na(+) ions in nucleic acid structures such as X-ray crystallography, nuclear magnetic resonance or molecular dynamics simulations. We also discuss specific versus non-specific binding to different structures through various examples.
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Affiliation(s)
- Pascal Auffinger
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC, CNRS, 15 rue René Descartes, F-67084, Strasbourg, France.
| | - Luigi D'Ascenzo
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC, CNRS, 15 rue René Descartes, F-67084, Strasbourg, France.
| | - Eric Ennifar
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC, CNRS, 15 rue René Descartes, F-67084, Strasbourg, France.
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Niyogi S, Docampo R. A novel role of Rab11 in trafficking GPI-anchored trans-sialidase to the plasma membrane of Trypanosoma cruzi. Small GTPases 2015; 6:8-10. [PMID: 25862161 DOI: 10.4161/21541248.2014.978712] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Trypanosoma cruzi, the causative agent of Chagas disease, is a unicellular parasite that possesses a contractile vacuole complex (CVC). This organelle is usually present in free-living protists and is mainly involved in osmoregulation. However, in some organisms, like for example Dictyostelium discoideum, other roles include calcium homeostasis and transference of proteins to the plasma membrane. T. cruzi plasma membrane is very rich in glycosylphosphatidylinositol anchored proteins (GPI-AP) and a very important group of GPI-AP is that of the trans-sialidases. These enzymes catalyze the transfer of sialic acid from host glycoconjugates to mucins present in the surface of the parasite and are important for host cell invasion among other functions. We recently reported that a pathway dependent on the Rab GTPase Rab11 is involved in the traffic of trans-sialidases to the plasma membrane through the CVC of the infective stages of the parasite and that preventing this traffic results in considerable reduction in the ability of T. cruzi to infect host cells. We also found that traffic of other GPI-anchored proteins is also through the CVC but uses a Rab11-independent pathway. These represent unconventional pathways of GPI-anchored protein traffic to the plasma membrane.
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Affiliation(s)
- Sayantanee Niyogi
- a Center for Tropical and Emerging Global Diseases and Department of Cellular Biology ; University of Georgia ; Athens , Georgia , USA
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Baeza-Richer C, Arroyo-Pardo E, Blanco-Rojo R, Toxqui L, Remacha A, Vaquero MP, López-Parra AM. Genetic contribution to iron status: SNPs related to iron deficiency anaemia and fine mapping of CACNA2D3 calcium channel subunit. Blood Cells Mol Dis 2015; 55:273-80. [DOI: 10.1016/j.bcmd.2015.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 07/13/2015] [Accepted: 07/14/2015] [Indexed: 12/13/2022]
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133
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Fugelli K. Effects of sodium ions on rat thyrocyte (FRTL-5 cells) swelling- and thyrotropin-activated taurine efflux dependent on cAMP and Epac. Amino Acids 2015; 48:763-777. [PMID: 26553454 DOI: 10.1007/s00726-015-2124-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 10/26/2015] [Indexed: 11/25/2022]
Abstract
Cellular osmolyte release is important in preventing water accumulation and swelling. However, the signaling pathways that detect volume increase and activate solute efflux are still not fully understood. We investigated efflux activation of the osmolyte taurine which is actively accumulated in rat thyrocytes (FRTL-5). Efflux of accumulated [(3)H]taurine was stimulated by cellular swelling and thyrotropin (TSH). These effects were significantly diminished in cells having reduced TSH receptor concentrations. Phosphodiesterase inhibitors (IBMX, Rolipram) enhanced both responses. An analog of forskolin (FSK; 7-deacetyl-7-[O-(N-methylpiperazino)-γ-butyryl] dihydrochloride) and an analog of cAMP, specific for activating exchange protein activated directly by cAMP (Epac; 8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate, acetoxymethyl ester), significantly stimulated [(3)H]taurine efflux. A cAMP analog specific for activating protein kinase A (PKA; N6-benzoyladenosine-3',5'-cyclic monophosphate, acetoxymethyl ester) had no significant stimulatory effect on [(3)H]taurine efflux rate. The amiloride analog, 5-(N-ethyl-N-isopropyl)-amiloride, which inhibits a TSH-stimulated Na(+)/H(+) exchanger, enhanced (100 %) and ouabain inhibited (50 %) the TSH-stimulated [(3)H]taurine efflux rate. The effect of FSK on efflux was strongly potentiated by Na(+)-free iso-osmotic conditions and by osmolality/cell volume that affected also the db-cAMP-stimulated efflux. The TSH receptors and downstream elements of the signaling pathway comprising adenylyl cyclase, cAMP and Epac appeared to mediate the hormone-induced signal for [(3)H]taurine efflux from FRTL-5 cells. With less evidence, the cell volume/osmolality-induced [(3)H]taurine efflux cascade appeared to share some of the hormone signaling elements and to modulate the hormone signaling pathway at two levels through cellular Na(+).
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Affiliation(s)
- Kjell Fugelli
- Department of Biosciences, University of Oslo, POBox 1066, Blindern, 0316, Oslo, Norway.
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Up-regulation of epithelial Na(+) channel ENaC by human parvovirus B19 capsid protein VP1. Biochem Biophys Res Commun 2015; 468:179-84. [PMID: 26522226 DOI: 10.1016/j.bbrc.2015.10.137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 10/26/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND Clinical disorders caused by parvovirus B19 (B19V) infection include endothelial dysfunction with cardiac ischemia. The virus is effective in part by lysophosphatidylcholine-producing phospholipase A2 (PLA2) activity of B19V capsid protein VP1. Mechanisms compromising endothelial function include up-regulation of amiloride sensitive epithelial Na(+)-channel ENaC leading to endothelial cell stiffness. Regulators of ENaC include ubiquitin-ligase Nedd4-2. The present study explored whether VP1 modifies ENaC-activity. METHODS cRNA encoding ENaC was injected into Xenopus oocytes without or with cRNA encoding VP1. Experiments were made with or without coexpression of Nedd4-2. ENaC activity was estimated from amiloride (50 μM) sensitive current. RESULTS Injection of cRNA encoding ENaC into Xenopus oocytes was followed by appearance of amiloride sensitive current, which was significantly enhanced by additional injection of cRNA encoding VP1, but not by additional injection of cRNA encoding PLA2-negative VP1 mutant (H153A). The effect of VP1 on ENaC was mimicked by treatment of ENaC expressing oocytes with lysophosphatidylcholine (1 μg/ml). The effect of VP1 and lysophosphatidylcholine was not additive. ENaC activity was downregulated by Nedd4-2, an effect not reversed by VP1. CONCLUSIONS The B19V capsid protein VP1 up-regulates ENaC, an effect at least partially due to phospholipase A2 (PLA) dependent formation of lysophosphatidylcholine.
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Fezai M, Elvira B, Warsi J, Ben-Attia M, Hosseinzadeh Z, Lang F. Up-Regulation of Intestinal Phosphate Transporter NaPi-IIb (SLC34A2) by the Kinases SPAK and OSR1. Kidney Blood Press Res 2015; 40:555-64. [PMID: 26506223 DOI: 10.1159/000368531] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS SPAK (SPS1-related proline/alanine-rich kinase) and OSR1 (oxidative stress-responsive kinase 1), kinases controlled by WNK (with-no-K[Lys] kinase), are powerful regulators of cellular ion transport and blood pressure. Observations in gene-targeted mice disclosed an impact of SPAK/OSR1 on phosphate metabolism. The present study thus tested whether SPAK and/or OSR1 contributes to the regulation of the intestinal Na(+)-coupled phosphate co-transporter NaPi-IIb (SLC34A2). METHODS cRNA encoding NaPi-IIb was injected into Xenopus laevis oocytes without or with additional injection of cRNA encoding wild-type SPAK, constitutively active (T233E)SPAK, WNK insensitive (T233A)SPAK, catalytically inactive (D212A)SPAK, wild-type OSR1, constitutively active (T185E)OSR1, WNK insensitive (T185A)OSR1 or catalytically inactive (D164A)OSR1. The phosphate (1 mM)-induced inward current (I(Pi)) was taken as measure of phosphate transport. RESULTS I(Pi) was observed in NaPi-IIb expressing oocytes but not in water injected oocytes, and was significantly increased by co-expression of SPAK, (T233E)SPAK, OSR1, (T185E)OSR1 or SPAK+OSR1, but not by co-expression of (T233A)SPAK, (D212A)SPAK, (T185A)OSR1, or (D164A)OSR1. SPAK and OSR1 both increased the maximal transport rate of the carrier. CONCLUSIONS SPAK and OSR1 are powerful stimulators of the intestinal Na+-coupled phosphate co-transporter NaPi-IIb.
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Affiliation(s)
- Myriam Fezai
- Department of Physiology I, University of Tx00FC;bingen, Tx00FC;bingen, Germany
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Alleviation of Carbon-Tetrachloride-Induced Liver Injury and Fibrosis by Betaine Supplementation in Chickens. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:725379. [PMID: 26491462 PMCID: PMC4600548 DOI: 10.1155/2015/725379] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/28/2015] [Accepted: 09/02/2015] [Indexed: 01/18/2023]
Abstract
Betaine is a food component with well-reported hepatoprotection effects. However, the effects and mechanisms of betaine on liver fibrosis development are still insufficient. Because metabolic functions of chicken and human liver is similar, we established a chicken model with carbon Tetrachloride- (CCl4-) induced fibrosis for studying antifibrotic effect of betaine in vivo and in vitro. Two-week-old male chicks were supplemented with betaine (1%, w/v) in drinking water for 2 weeks prior to the initiation of CCl4 treatment (i.p.) until sacrifice. Primary chicken hepatocytes were treated with CCl4 and betaine to mimic the in vivo supplementation. The supplementation of betaine significantly alleviated liver fibrosis development along with the inhibition of lipid peroxidation, hepatic inflammation cytokine, and transforming growth factor-β1 expression levels. These inhibitive effects were also accompanied with the attenuation of hepatic stellate cell activation. Furthermore, our in vitro studies confirmed that betaine provides antioxidant capacity for attenuating the hepatocyte necrosis by CCl4. Altogether, our results highlight the antioxidant ability of betaine, which alleviates CCl4-induced fibrogenesis process along with the suppression of hepatic stellate cells activation. Since betaine is a natural compound without toxicity, we suggest betaine can be used as a potent nutritional or therapeutic factor for reducing liver fibrosis.
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137
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Pearson SJ, Hussain SR. A review on the mechanisms of blood-flow restriction resistance training-induced muscle hypertrophy. Sports Med 2015; 45:187-200. [PMID: 25249278 DOI: 10.1007/s40279-014-0264-9] [Citation(s) in RCA: 246] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
It has traditionally been believed that resistance training can only induce muscle growth when the exercise intensity is greater than 65% of the 1-repetition maximum (RM). However, more recently, the use of low-intensity resistance exercise with blood-flow restriction (BFR) has challenged this theory and consistently shown that hypertrophic adaptations can be induced with much lower exercise intensities (<50% 1-RM). Despite the potent hypertrophic effects of BFR resistance training being demonstrated by numerous studies, the underlying mechanisms responsible for such effects are not well defined. Metabolic stress has been suggested to be a primary factor responsible, and this is theorised to activate numerous other mechanisms, all of which are thought to induce muscle growth via autocrine and/or paracrine actions. However, it is noteworthy that some of these mechanisms do not appear to be mediated to any great extent by metabolic stress but rather by mechanical tension (another primary factor of muscle hypertrophy). Given that the level of mechanical tension is typically low with BFR resistance exercise (<50% 1-RM), one may question the magnitude of involvement of these mechanisms aligned to the adaptations reported with BFR resistance training. However, despite the low level of mechanical tension, it is plausible that the effects induced by the primary factors (mechanical tension and metabolic stress) are, in fact, additive, which ultimately contributes to the adaptations seen with BFR resistance training. Exercise-induced mechanical tension and metabolic stress are theorised to signal a number of mechanisms for the induction of muscle growth, including increased fast-twitch fibre recruitment, mechanotransduction, muscle damage, systemic and localised hormone production, cell swelling, and the production of reactive oxygen species and its variants, including nitric oxide and heat shock proteins. However, the relative extent to which these specific mechanisms are induced by the primary factors with BFR resistance exercise, as well as their magnitude of involvement in BFR resistance training-induced muscle hypertrophy, requires further exploration.
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Affiliation(s)
- Stephen John Pearson
- Centre for Health, Sport and Rehabilitation Sciences Research, University of Salford, Manchester, M6 6PU, UK,
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138
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El-Sharkawy AM, Sahota O, Lobo DN. Acute and chronic effects of hydration status on health. Nutr Rev 2015; 73 Suppl 2:97-109. [DOI: 10.1093/nutrit/nuv038] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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Rose KL, Watson AJ, Drysdale TA, Cepinskas G, Chan M, Rupar CA, Fraser DD. Simulated diabetic ketoacidosis therapy in vitro elicits brain cell swelling via sodium-hydrogen exchange and anion transport. Am J Physiol Endocrinol Metab 2015; 309:E370-9. [PMID: 26081282 DOI: 10.1152/ajpendo.00107.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 06/11/2015] [Indexed: 01/08/2023]
Abstract
A common complication of type 1 diabetes mellitus is diabetic ketoacidosis (DKA), a state of severe insulin deficiency. A potentially harmful consequence of DKA therapy in children is cerebral edema (DKA-CE); however, the mechanisms of therapy-induced DKA-CE are unknown. Our aims were to identify the DKA treatment factors and membrane mechanisms that might contribute specifically to brain cell swelling. To this end, DKA was induced in juvenile mice with the administration of the pancreatic toxins streptozocin and alloxan. Brain slices were prepared and exposed to DKA-like conditions in vitro. Cell volume changes were imaged in response to simulated DKA therapy. Our experiments showed that cell swelling was elicited with isolated DKA treatment components, including alkalinization, insulin/alkalinization, and rapid reductions in osmolality. Methyl-isobutyl-amiloride, a nonselective inhibitor of sodium-hydrogen exchangers (NHEs), reduced cell swelling in brain slices elicited with simulated DKA therapy (in vitro) and decreased brain water content in juvenile DKA mice administered insulin and rehydration therapy (in vivo). Specific pharmacological inhibition of the NHE1 isoform with cariporide also inhibited cell swelling, but only in the presence of the anion transport (AT) inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid. DKA did not alter brain NHE1 isoform expression, suggesting that the cell swelling attributed to the NHE1 was activity dependent. In conclusion, our data raise the possibility that brain cell swelling can be elicited by DKA treatment factors and that it is mediated by NHEs and/or coactivation of NHE1 and AT.
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Affiliation(s)
- Keeley L Rose
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada; Children's Health Research Institute, London, Ontario, Canada
| | - Andrew J Watson
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada; Children's Health Research Institute, London, Ontario, Canada
| | - Thomas A Drysdale
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada; Children's Health Research Institute, London, Ontario, Canada; Department of Paediatrics, Western University, London, Ontario, Canada
| | | | - Melissa Chan
- Children's Health Research Institute, London, Ontario, Canada
| | - C Anthony Rupar
- Children's Health Research Institute, London, Ontario, Canada; Department of Paediatrics, Western University, London, Ontario, Canada
| | - Douglas D Fraser
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada; Children's Health Research Institute, London, Ontario, Canada; Centre for Critical Illness Research, London, Ontario, Canada; Department of Paediatrics, Western University, London, Ontario, Canada; Department of Clinical Neurological Sciences, Western University, London, Ontario, Canada; and Translational Research Centre, London, Ontario, Canada
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140
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Abousaab A, Warsi J, Elvira B, Alesutan I, Hoseinzadeh Z, Lang F. Down-Regulation of Excitatory Amino Acid Transporters EAAT1 and EAAT2 by the Kinases SPAK and OSR1. J Membr Biol 2015; 248:1107-19. [PMID: 26233565 DOI: 10.1007/s00232-015-9826-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 07/24/2015] [Indexed: 11/27/2022]
Abstract
SPAK (SPS1-related proline/alanine-rich kinase) and OSR1 (oxidative stress-responsive kinase 1) are cell volume-sensitive kinases regulated by WNK (with-no-K[Lys]) kinases. SPAK/OSR1 regulate several channels and carriers. SPAK/OSR1 sensitive functions include neuronal excitability. Orchestration of neuronal excitation involves the excitatory glutamate transporters EAAT1 and EAAT2. Sensitivity of those carriers to SPAK/OSR1 has never been shown. The present study thus explored whether SPAK and/or OSR1 contribute to the regulation of EAAT1 and/or EAAT2. To this end, cRNA encoding EAAT1 or EAAT2 was injected into Xenopus oocytes without or with additional injection of cRNA encoding wild-type SPAK or wild-type OSR1, constitutively active (T233E)SPAK, WNK insensitive (T233A)SPAK, catalytically inactive (D212A)SPAK, constitutively active (T185E)OSR1, WNK insensitive (T185A)OSR1 or catalytically inactive (D164A)OSR1. The glutamate (2 mM)-induced inward current (I Glu) was taken as a measure of glutamate transport. As a result, I Glu was observed in EAAT1- and in EAAT2-expressing oocytes but not in water-injected oocytes, and was significantly decreased by coexpression of SPAK and OSR1. As shown for EAAT2, SPAK, and OSR1 decreased significantly the maximal transport rate but significantly enhanced the affinity of the carrier. The effect of wild-type SPAK/OSR1 on EAAT1 and EAAT2 was mimicked by (T233E)SPAK and (T185E)OSR1, but not by (T233A)SPAK, (D212A)SPAK, (T185A)OSR1, or (D164A)OSR1. Coexpression of either SPAK or OSR1 decreased the EAAT2 protein abundance in the cell membrane of EAAT2-expressing oocytes. In conclusion, SPAK and OSR1 are powerful negative regulators of the excitatory glutamate transporters EAAT1 and EAAT2.
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Affiliation(s)
- Abeer Abousaab
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany
| | - Jamshed Warsi
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany
| | - Bernat Elvira
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany
| | - Ioana Alesutan
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany
| | - Zohreh Hoseinzadeh
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany
| | - Florian Lang
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany.
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Friedel P, Kahle KT, Zhang J, Hertz N, Pisella LI, Buhler E, Schaller F, Duan J, Khanna AR, Bishop PN, Shokat KM, Medina I. WNK1-regulated inhibitory phosphorylation of the KCC2 cotransporter maintains the depolarizing action of GABA in immature neurons. Sci Signal 2015; 8:ra65. [PMID: 26126716 DOI: 10.1126/scisignal.aaa0354] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Activation of Cl(-)-permeable γ-aminobutyric acid type A (GABAA) receptors elicits synaptic inhibition in mature neurons but excitation in immature neurons. This developmental "switch" in the GABA function depends on a postnatal decrease in intraneuronal Cl(-) concentration mediated by KCC2, a Cl(-)-extruding K(+)-Cl(-) cotransporter. We showed that the serine-threonine kinase WNK1 [with no lysine (K)] forms a physical complex with KCC2 in the developing mouse brain. Dominant-negative mutation, genetic depletion, or chemical inhibition of WNK1 in immature neurons triggered a hyperpolarizing shift in GABA activity by enhancing KCC2-mediated Cl(-) extrusion. This increase in KCC2 activity resulted from reduced inhibitory phosphorylation of KCC2 at two C-terminal threonines, Thr(906) and Thr(1007). Phosphorylation of both Thr(906) and Thr(1007) was increased in immature versus mature neurons. Together, these data provide insight into the mechanism regulating Cl(-) homeostasis in immature neurons, and suggest that WNK1-regulated changes in KCC2 phosphorylation contribute to the developmental excitatory-to-inhibitory GABA sequence.
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Affiliation(s)
- Perrine Friedel
- Institut de Neurobiologie de la Méditerranée (INMED), INSERM Unité 901, 13273 Marseille, France. Aix-Marseille Université, UMR 901, 13273 Marseille, France
| | - Kristopher T Kahle
- Department of Neurosurgery, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
| | - Jinwei Zhang
- UK Medical Research Council Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Nicholas Hertz
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94143-0450, USA
| | - Lucie I Pisella
- Institut de Neurobiologie de la Méditerranée (INMED), INSERM Unité 901, 13273 Marseille, France. Aix-Marseille Université, UMR 901, 13273 Marseille, France
| | - Emmanuelle Buhler
- Aix-Marseille Université, UMR 901, 13273 Marseille, France. Plateforme Post-Génomique, INMED, 13273 Marseille, France
| | - Fabienne Schaller
- Aix-Marseille Université, UMR 901, 13273 Marseille, France. Plateforme Post-Génomique, INMED, 13273 Marseille, France
| | - JingJing Duan
- Department of Neurosurgery, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Arjun R Khanna
- Department of Neurosurgery, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Paul N Bishop
- School of Biochemistry, University of Bristol, Bristol BS8 1TH, UK
| | - Kevan M Shokat
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94143-0450, USA
| | - Igor Medina
- Institut de Neurobiologie de la Méditerranée (INMED), INSERM Unité 901, 13273 Marseille, France. Aix-Marseille Université, UMR 901, 13273 Marseille, France.
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Borrás J, Salker MS, Elvira B, Warsi J, Fezai M, Hoseinzadeh Z, Lang F. SPAK and OSR1 Sensitivity of Excitatory Amino Acid Transporter EAAT3. Nephron Clin Pract 2015; 130:221-8. [PMID: 26112741 DOI: 10.1159/000433567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/20/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Kinases involved in the regulation of epithelial transport include SPAK (SPS1-related proline/alanine-rich kinase) and OSR1 (oxidative stress-responsive kinase 1). SPAK and OSR1 are both regulated by WNK (with-no-K(Lys)) kinases. The present study explored whether SPAK and/or OSR1 influence the excitatory amino acid transporter EAAT3, which accomplishes glutamate and aspartate transport in kidney, intestine and brain. METHODS cRNA encoding EAAT3 was injected into Xenopus laevis oocytes with or without additional injection of cRNA encoding wild-type SPAK, constitutively active (T233E)SPAK, WNK insensitive (T233A)SPAK, catalytically inactive (D212A)SPAK, wild-type OSR1, constitutively active (T185E)OSR1, WNK insensitive (T185A)OSR1 and catalytically inactive (D164A)OSR1. Glutamate-induced current was taken as measure of electrogenic glutamate transport and was quantified utilizing dual electrode voltage clamp. Furthermore, Ussing chamber was employed to determine glutamate transport in the intestine from gene-targeted mice carrying WNK insensitive SPAK (spak(tg/tg)) and from corresponding wild-type mice (spak(+/+)). RESULTS EAAT3 activity was significantly decreased by wild-type SPAK and (T233E)SPAK, but not by (T233A)SPAK and (D212A)SPAK. SPAK decreased maximal transport rate without affecting significantly affinity of the carrier. Similarly, EAAT3 activity was significantly downregulated by wild-type OSR1 and (T185E)OSR1, but not by (T185A)OSR1 and (D164A)OSR1. Again OSR1 decreased maximal transport rate without affecting significantly affinity of the carrier. Intestinal electrogenic glutamate transport was significantly lower in spak(+/+) than in spak(tg/tg) mice. CONCLUSION Both, SPAK and OSR1 are negative regulators of EAAT3 activity.
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Affiliation(s)
- José Borrás
- Department of Physiology I, University of Tübingen, Tubingen, Germany
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143
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Prager-Khoutorsky M, Bourque CW. Mechanical basis of osmosensory transduction in magnocellular neurosecretory neurones of the rat supraoptic nucleus. J Neuroendocrinol 2015; 27:507-15. [PMID: 25712904 DOI: 10.1111/jne.12270] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 02/19/2015] [Accepted: 02/22/2015] [Indexed: 12/31/2022]
Abstract
Rat magnocellular neurosecretory cells (MNCs) release vasopressin and oxytocin to promote antidiuresis and natriuresis at the kidney. The osmotic control of oxytocin and vasopressin release at the neurohypophysis is required for osmoregulation in these animals, and this release is mediated by a modulation of the action potential firing rate by the MNCs. Under basal (isotonic) conditions, MNCs fire action potentials at a slow rate, and this activity is inhibited by hypo-osmotic conditions and enhanced by hypertonicity. The effects of changes in osmolality on MNCs are mediated by a number of different factors, including the involvement of synaptic inputs, the release of taurine by local glial cells and regulation of ion channels expressed within the neurosecretory neurones themselves. We review recent findings that have clarified our understanding of how osmotic stimuli modulate the activity of nonselective cation channels in MNCs. Previous studies have shown that osmotically-evoked changes in membrane potential and action potential firing rate in acutely isolated MNCs are provoked mainly by a modulation of nonselective cation channels. Notably, the excitation of isolated MNCs during hypertonicity is mediated by the activation of a capsaicin-insensitive cation channel that MNCs express as an N-terminal variant of the transient receptor potential vanilloid 1 (Trpv1) channel. The activation of this channel during hypertonicity is a mechanical process associated with cell shrinking. The effectiveness of this mechanical process depends on the presence of a thin layer of actin filaments (F-actin) beneath the plasma membrane, as well as a densely interweaved network of microtubules (MTs) occupying the bulk of the cytoplasm of MNCs. Although the mechanism by which F-actin contributes to Trpv1 activation remains unknown, recent data have shown that MTs interact with Trpv1 channels via binding sites on the C-terminus, and that the force mediated through this complex is required for channel gating during osmosensory transduction. Indeed, displacement of this interaction prevents channel activation during shrinking, whereas increasing the density of these interaction sites potentiates shrinking-induced activation of Trpv1. Therefore, the gain of the osmosensory transduction process can be regulated bi-directionally through changes in the organisation of F-actin and MTs.
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Affiliation(s)
- M Prager-Khoutorsky
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
| | - C W Bourque
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
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144
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Hefni M, McEntyre C, Lever M, Slow S. Validation of HPLC-UV Methods for the Quantification of Betaine in Foods by Comparison with LC-MS. FOOD ANAL METHOD 2015. [DOI: 10.1007/s12161-015-0195-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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145
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Scott BR, Slattery KM, Sculley DV, Dascombe BJ. Hypoxia and resistance exercise: a comparison of localized and systemic methods. Sports Med 2015; 44:1037-54. [PMID: 24715613 DOI: 10.1007/s40279-014-0177-7] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
It is generally believed that optimal hypertrophic and strength gains are induced through moderate- or high-intensity resistance training, equivalent to at least 60% of an individual's 1-repetition maximum (1RM). However, recent evidence suggests that similar adaptations are facilitated when low-intensity resistance exercise (~20-50% 1RM) is combined with blood flow restriction (BFR) to the working muscles. Although the mechanisms underpinning these responses are not yet firmly established, it appears that localized hypoxia created by BFR may provide an anabolic stimulus by enhancing the metabolic and endocrine response, and increase cellular swelling and signalling function following resistance exercise. Moreover, BFR has also been demonstrated to increase type II muscle fibre recruitment during exercise. However, inappropriate implementation of BFR can result in detrimental effects, including petechial haemorrhage and dizziness. Furthermore, as BFR is limited to the limbs, the muscles of the trunk are unable to be trained under localized hypoxia. More recently, the use of systemic hypoxia via hypoxic chambers and devices has been investigated as a novel way to stimulate similar physiological responses to resistance training as BFR techniques. While little evidence is available, reports indicate that beneficial adaptations, similar to those induced by BFR, are possible using these methods. The use of systemic hypoxia allows large groups to train concurrently within a hypoxic chamber using multi-joint exercises. However, further scientific research is required to fully understand the mechanisms that cause augmented muscular changes during resistance exercise with a localized or systemic hypoxic stimulus.
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Affiliation(s)
- Brendan R Scott
- Applied Sports Science and Exercise Testing Laboratory, School of Environmental and Life Sciences, Faculty of Science and Information Technology, University of Newcastle, PO Box 127, Ourimbah, NSW, 2258, Australia,
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146
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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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147
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Salt and osmosensing: role of cytoplasmic hydrogel. Pflugers Arch 2015; 467:475-87. [DOI: 10.1007/s00424-014-1680-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 12/17/2014] [Accepted: 12/18/2014] [Indexed: 12/30/2022]
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148
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Karjalainen HM, Qu C, Leskelä SS, Rilla K, Lammi MJ. Chondrocytic cells express the taurine transporter on their plasma membrane and regulate its expression under anisotonic conditions. Amino Acids 2014; 47:561-70. [PMID: 25501278 DOI: 10.1007/s00726-014-1888-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 12/01/2014] [Indexed: 10/24/2022]
Abstract
Taurine is a small organic osmolyte which participates in cell volume regulation. Chondrocytes have been shown to accumulate and release taurine; in bone, taurine participates in bone metabolism. However, its role in skeletal cells is poorly understood, especially in chondrocytes. This study investigated the regulation of taurine transporter in chondrocytic cells. We examined the transcriptional regulation of the taurine transporter under anisotonia by reporter gene and real-time RT-PCR assays. The effect of providing supplementary taurine on cell viability was evaluated with the lactate dehydrogenase release assay. The localization of the taurine transporter in human chondrosarcoma cells was studied by overexpressing a taurine transporter-enhanced green fluorescent protein. We observed that the transcription of the taurine transporter gene was up-regulated in hypertonic conditions. Hyperosmolarity-related cell death could be partly abolished by taurine supplementation in the medium. As expected, the fluorescently labeled taurine transporter localized at the plasma membrane. In polarized epithelial MDCK cells, the strongest fluorescence signal was located in the lateral cell membrane area. We also observed that the taurine transporter gene was expressed in several human tissues and malignant cell lines. This is the first study to present information on the transcriptional regulation of taurine transporter gene and the localization of the taurine transporter protein in chondrocytic cells.
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Affiliation(s)
- Hannu M Karjalainen
- School of Medicine, Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland,
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149
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Ahmed M, Elvira B, Almilaji A, Bock CT, Kandolf R, Lang F. Down-regulation of inwardly rectifying Kir2.1 K+ channels by human parvovirus B19 capsid protein VP1. J Membr Biol 2014; 248:223-9. [PMID: 25487255 DOI: 10.1007/s00232-014-9762-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 11/21/2014] [Indexed: 01/18/2023]
Abstract
Parvovirus B19 (B19V) has previously been shown to cause endothelial dysfunction. B19V capsid protein VP1 harbors a lysophosphatidylcholine producing phospholipase A2 (PLA2). Lysophosphatidylcholine inhibits Na(+)/K(+) ATPase, which in turn may impact on the activity of inwardly rectifying K(+) channels. The present study explored whether VP1 modifies the activity of Kir2.1 K(+) channels. cRNA encoding Kir2.1 was injected into Xenopus oocytes without or with cRNA encoding VP1 isolated from a patient suffering from fatal B19V-induced inflammatory cardiomyopathy or the VP1 mutant (H153A)VP1 lacking a functional PLA2 activity. K(+) channel activity was determined by dual electrode voltage clamp. In addition, Na(+)/K(+)-ATPase activity was estimated from K(+)-induced pump current (I(pump)) and ouabain-inhibited current (I(ouabain)). Injection of cRNA encoding Kir2.1 into Xenopus oocytes was followed by appearance of inwardly rectifying K(+) channel activity (I(K)), which was significantly decreased by additional injection of cRNA encoding VP1, but not by additional injection of cRNA encoding (H153A)VP1. The effect of VP1 on I K was mimicked by lysophosphatidylcholine (1 μg/ml) and by inhibition of Na(+)/K(+)-ATPase with 0.1 mM ouabain. In the presence of lysophosphatidylcholine, I K was not further decreased by additional treatment with ouabain. The B19V capsid protein VP1 thus inhibits Kir2.1 channels, an effect at least partially due to PLA2-dependent formation of lysophosphatidylcholine with subsequent inhibition of Na(+)/K(+)-ATPase activity.
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Affiliation(s)
- Musaab Ahmed
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany
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150
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Zhang H, Li H, Liu E, Guang Y, Yang L, Mao J, Zhu L, Chen L, Wang L. The AQP-3 water channel and the ClC-3 chloride channel coordinate the hypotonicity-induced swelling volume in nasopharyngeal carcinoma cells. Int J Biochem Cell Biol 2014; 57:96-107. [DOI: 10.1016/j.biocel.2014.10.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 10/06/2014] [Accepted: 10/08/2014] [Indexed: 11/25/2022]
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