1
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Olver DJ, Azam I, Benson JD. HepG2 cells undergo regulatory volume decrease by mechanically induced efflux of water and solutes. Biomech Model Mechanobiol 2024; 23:1781-1799. [PMID: 39012455 DOI: 10.1007/s10237-024-01868-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 06/12/2024] [Indexed: 07/17/2024]
Abstract
This study challenges the conventional belief that animal cell membranes lack a significant hydrostatic gradient, particularly under anisotonic conditions, as demonstrated in the human hepatoma cell line HepG2. The Boyle van't Hoff (BvH) relation describes volumetric equilibration to anisotonic conditions for many cells. However, the BvH relation is simple and does not include many cellular components such as the cytoskeleton and actin cortex, mechanosensitive channels, and ion pumps. Here we present alternative models that account for mechanical resistance to volumetric expansion, solute leakage, and active ion pumping. We found the BvH relation works well to describe hypertonic volume equilibration but not hypotonic volume equilibration. After anisotonic exposure and return isotonic conditions cell volumes were smaller than their initial isotonic volume, indicating solutes had leaked out of the cell during swelling. Finally, we observed HepG2 cells undergo regulatory volume decrease at both 20 °C and 4 °C, indicating regulatory volume decrease to be a relatively passive phenomenon and not driven by ion pumps. We determined the turgor-leak model, which accounts for mechanical resistance and solute leakage, best fits the observations found in the suite of experiments performed, while other models were rejected.
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Affiliation(s)
- Dominic J Olver
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada
| | - Iqra Azam
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada
| | - James D Benson
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada.
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2
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Olver DJ, Benson JD. Meta-analysis of the Boyle van 't Hoff relation: Turgor and leak models explain non-ideal volume equilibrium. Cryobiology 2023; 113:104581. [PMID: 37661046 DOI: 10.1016/j.cryobiol.2023.104581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 08/06/2023] [Accepted: 08/26/2023] [Indexed: 09/05/2023]
Abstract
There has been much recent attention paid to the interaction of cell volume, its regulation, and the molecular biology of the cell. Cells are generally assumed to behave as linear osmometers, with their water volume linearly proportionate to the inverse of osmotic pressure as described by the Boyle van 't Hoff (BvH) relation. This study evaluates the generality of this and other long-standing assumptions about cell responses to anisotonic conditions. We present alternative models that account for osmoregulation including mechanical resistance to volumetric expansion (the turgor model) and ion-osmolyte leakage (the leak model). To evaluate the generality of the BvH relation and determine the suitability of alternative models, we performed a comprehensive survey of the literature and a careful analysis of the resulting data, and then we used these data to compare among models. We identified 137 articles published from 1964 to 2019 spanning 14 animal species and 26 cell types and determined the BvH relation is not an appropriate general model but is adequate when restricted to the hypertonic region. In contrast, models that account for either mechanical resistance or ion-osmolyte leakage fit well to almost all collected data. The leak model has fitted parameters that are in the same range as the current literature estimate, while the turgor model typically requires an elastic modulus value of one or multiple orders of magnitude larger than literature values. However, confirmation of the underlying mechanism of osmotic regulation is required at the cell-specific level and cannot be assumed a priori.
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Affiliation(s)
- Dominic J Olver
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada
| | - James D Benson
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada.
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Dabbagh F, Schroten H, Schwerk C. In Vitro Models of the Blood–Cerebrospinal Fluid Barrier and Their Applications in the Development and Research of (Neuro)Pharmaceuticals. Pharmaceutics 2022; 14:pharmaceutics14081729. [PMID: 36015358 PMCID: PMC9412499 DOI: 10.3390/pharmaceutics14081729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/11/2022] [Accepted: 08/16/2022] [Indexed: 11/30/2022] Open
Abstract
The pharmaceutical research sector has been facing the challenge of neurotherapeutics development and its inherited high-risk and high-failure-rate nature for decades. This hurdle is partly attributable to the presence of brain barriers, considered both as obstacles and opportunities for the entry of drug substances. The blood–cerebrospinal fluid (CSF) barrier (BCSFB), an under-studied brain barrier site compared to the blood–brain barrier (BBB), can be considered a potential therapeutic target to improve the delivery of CNS therapeutics and provide brain protection measures. Therefore, leveraging robust and authentic in vitro models of the BCSFB can diminish the time and effort spent on unproductive or redundant development activities by a preliminary assessment of the desired physiochemical behavior of an agent toward this barrier. To this end, the current review summarizes the efforts and progresses made to this research area with a notable focus on the attribution of these models and applied techniques to the pharmaceutical sector and the development of neuropharmacological therapeutics and diagnostics. A survey of available in vitro models, with their advantages and limitations and cell lines in hand will be provided, followed by highlighting the potential applications of such models in the (neuro)therapeutics discovery and development pipelines.
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Gómez-González GB, Becerra-González M, Martínez-Mendoza ML, Rodríguez-Arzate CA, Martínez-Torres A. Organization of the ventricular zone of the cerebellum. Front Cell Neurosci 2022; 16:955550. [PMID: 35959470 PMCID: PMC9358289 DOI: 10.3389/fncel.2022.955550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 07/06/2022] [Indexed: 11/14/2022] Open
Abstract
The roof of the fourth ventricle (4V) is located on the ventral part of the cerebellum, a region with abundant vascularization and cell heterogeneity that includes tanycyte-like cells that define a peculiar glial niche known as ventromedial cord. This cord is composed of a group of biciliated cells that run along the midline, contacting the ventricular lumen and the subventricular zone. Although the complex morphology of the glial cells composing the cord resembles to tanycytes, cells which are known for its proliferative capacity, scarce or non-proliferative activity has been evidenced in this area. The subventricular zone of the cerebellum includes astrocytes, oligodendrocytes, and neurons whose function has not been extensively studied. This review describes to some extent the phenotypic, morphological, and functional characteristics of the cells that integrate the roof of the 4V, primarily from rodent brains.
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Mecawi AS, Varanda WA, da Silva MP. Osmoregulation and the Hypothalamic Supraoptic Nucleus: From Genes to Functions. Front Physiol 2022; 13:887779. [PMID: 35685279 PMCID: PMC9171026 DOI: 10.3389/fphys.2022.887779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022] Open
Abstract
Due to the relatively high permeability to water of the plasma membrane, water tends to equilibrate its chemical potential gradient between the intra and extracellular compartments. Because of this, changes in osmolality of the extracellular fluid are accompanied by changes in the cell volume. Therefore, osmoregulatory mechanisms have evolved to keep the tonicity of the extracellular compartment within strict limits. This review focuses on the following aspects of osmoregulation: 1) the general problems in adjusting the "milieu interieur" to challenges imposed by water imbalance, with emphasis on conceptual aspects of osmosis and cell volume regulation; 2) osmosensation and the hypothalamic supraoptic nucleus (SON), starting with analysis of the electrophysiological responses of the magnocellular neurosecretory cells (MNCs) involved in the osmoreception phenomenon; 3) transcriptomic plasticity of SON during sustained hyperosmolality, to pinpoint the genes coding membrane channels and transporters already shown to participate in the osmosensation and new candidates that may have their role further investigated in this process, with emphasis on those expressed in the MNCs, discussing the relationships of hydration state, gene expression, and MNCs electrical activity; and 4) somatodendritic release of neuropeptides in relation to osmoregulation. Finally, we expect that by stressing the relationship between gene expression and the electrical activity of MNCs, studies about the newly discovered plastic-regulated genes that code channels and transporters in the SON may emerge.
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Affiliation(s)
- André Souza Mecawi
- Laboratory of Molecular Neuroendocrinology, Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Wamberto Antonio Varanda
- Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Melina Pires da Silva
- Laboratory of Cellular Neuroendocrinology, Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
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Li Y, Zhou X, Sun SX. Hydrogen, Bicarbonate, and Their Associated Exchangers in Cell Volume Regulation. Front Cell Dev Biol 2021; 9:683686. [PMID: 34249935 PMCID: PMC8264760 DOI: 10.3389/fcell.2021.683686] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 05/31/2021] [Indexed: 11/25/2022] Open
Abstract
Cells lacking a stiff cell wall, e.g., mammalian cells, must actively regulate their volume to maintain proper cell function. On the time scale that protein production is negligible, water flow in and out of the cell determines the cell volume variation. Water flux follows hydraulic and osmotic gradients; the latter is generated by various ion channels, transporters, and pumps in the cell membrane. Compared to the widely studied roles of sodium, potassium, and chloride in cell volume regulation, the effects of proton and bicarbonate are less understood. In this work, we use mathematical models to analyze how proton and bicarbonate, combined with sodium, potassium, chloride, and buffer species, regulate cell volume upon inhibition of ion channels, transporters, and pumps. The model includes several common, widely expressed ion transporters and focuses on obtaining generic outcomes. Results show that the intracellular osmolarity remains almost constant before and after cell volume change. The steady-state cell volume does not depend on water permeability. In addition, to ensure the stability of cell volume and ion concentrations, cells need to develop redundant mechanisms to maintain homeostasis, i.e., multiple ion channels or transporters are involved in the flux of the same ion species. These results provide insights for molecular mechanisms of cell volume regulation with additional implications for water-driven cell migration.
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Affiliation(s)
- Yizeng Li
- Department of Mechanical Engineering, Kennesaw State University, Marietta, GA, United States
| | - Xiaohan Zhou
- Department of Physics, University of Toronto, Toronto, ON, Canada
| | - Sean X. Sun
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, United States
- Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, United States
- Center for Cell Dynamics, Johns Hopkins School of Medicine, Baltimore, MD, United States
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8
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Alvarez-Leefmans FJ. CrossTalk proposal: Apical NKCC1 of choroid plexus epithelial cells works in the net inward flux mode under basal conditions, maintaining intracellular Cl - and cell volume. J Physiol 2020; 598:4733-4736. [PMID: 32870510 DOI: 10.1113/jp279867] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Francisco J Alvarez-Leefmans
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
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9
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Bothwell SW, Janigro D, Patabendige A. Cerebrospinal fluid dynamics and intracranial pressure elevation in neurological diseases. Fluids Barriers CNS 2019; 16:9. [PMID: 30967147 PMCID: PMC6456952 DOI: 10.1186/s12987-019-0129-6] [Citation(s) in RCA: 134] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 03/19/2019] [Indexed: 01/09/2023] Open
Abstract
The fine balance between the secretion, composition, volume and turnover of cerebrospinal fluid (CSF) is strictly regulated. However, during certain neurological diseases, this balance can be disrupted. A significant disruption to the normal CSF circulation can be life threatening, leading to increased intracranial pressure (ICP), and is implicated in hydrocephalus, idiopathic intracranial hypertension, brain trauma, brain tumours and stroke. Yet, the exact cellular, molecular and physiological mechanisms that contribute to altered hydrodynamic pathways in these diseases are poorly defined or hotly debated. The traditional views and concepts of CSF secretion, flow and drainage have been challenged, also due to recent findings suggesting more complex mechanisms of brain fluid dynamics than previously proposed. This review evaluates and summarises current hypotheses of CSF dynamics and presents evidence for the role of impaired CSF dynamics in elevated ICP, alongside discussion of the proteins that are potentially involved in altered CSF physiology during neurological disease. Undoubtedly CSF secretion, absorption and drainage are important aspects of brain fluid homeostasis in maintaining a stable ICP. Traditionally, pharmacological interventions or CSF drainage have been used to reduce ICP elevation due to over production of CSF. However, these drugs are used only as a temporary solution due to their undesirable side effects. Emerging evidence suggests that pharmacological targeting of aquaporins, transient receptor potential vanilloid type 4 (TRPV4), and the Na+-K+-2Cl- cotransporter (NKCC1) merit further investigation as potential targets in neurological diseases involving impaired brain fluid dynamics and elevated ICP.
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Affiliation(s)
- Steven William Bothwell
- Brain Barriers Group, School of Biomedical Sciences and Pharmacy, The University of Newcastle, Medical Sciences Building, University Drive, Callaghan, NSW 2308 Australia
| | - Damir Janigro
- FloTBI Inc., Cleveland, OH USA
- Department of Physiology, Case Western Reserve University, Cleveland, OH USA
| | - Adjanie Patabendige
- Brain Barriers Group, School of Biomedical Sciences and Pharmacy, The University of Newcastle, Medical Sciences Building, University Drive, Callaghan, NSW 2308 Australia
- Hunter Medical Research Institute, Newcastle, NSW Australia
- The Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
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10
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Gregoriades JMC, Madaris A, Alvarez FJ, Alvarez-Leefmans FJ. Genetic and pharmacological inactivation of apical Na +-K +-2Cl - cotransporter 1 in choroid plexus epithelial cells reveals the physiological function of the cotransporter. Am J Physiol Cell Physiol 2019; 316:C525-C544. [PMID: 30576237 PMCID: PMC6482671 DOI: 10.1152/ajpcell.00026.2018] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 12/03/2018] [Accepted: 12/03/2018] [Indexed: 01/08/2023]
Abstract
Choroid plexus epithelial cells (CPECs) secrete cerebrospinal fluid (CSF). They express Na+-K+-ATPase and Na+-K+-2Cl- cotransporter 1 (NKCC1) on their apical membrane, deviating from typical basolateral membrane location in secretory epithelia. Given this peculiarity, the direction of basal net ion fluxes mediated by NKCC1 in CPECs is controversial, and cotransporter function is unclear. Determining the direction of basal NKCC1-mediated fluxes is critical to understanding the function of apical NKCC1. If NKCC1 works in the net efflux mode, it may be directly involved in CSF secretion. Conversely, if NKCC1 works in the net influx mode, it would have an absorptive function, contributing to intracellular Cl- concentration ([Cl-]i) and cell water volume (CWV) maintenance needed for CSF secretion. We resolve this long-standing debate by electron microscopy (EM), live-cell-imaging microscopy (LCIM), and intracellular Na+ and Cl- measurements in single CPECs of NKCC1+/+ and NKCC1-/- mouse. NKCC1-mediated ion and associated water fluxes are tightly linked, thus their direction is inferred by measuring CWV changes. Genetic or pharmacological NKCC1 inactivation produces CPEC shrinkage. EM of NKCC1-/- CPECs in situ shows they are shrunken, forming large dilations of their basolateral extracellular spaces, yet remaining attached by tight junctions. Normarski LCIM shows in vitro CPECs from NKCC1-/- are ~17% smaller than NKCC1+/+. CWV measurements in calcein-loaded CPECs show that bumetanide (10 μM) produces ~16% decrease in CWV in NKCC1+/+ but not in NKCC1-/- CPECs. Our findings suggest that under basal conditions apical NKCC1 is continuously active and works in the net inward flux mode maintaining [Cl-]i and CWV needed for CSF secretion.
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Affiliation(s)
- Jeannine M C Gregoriades
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University , Dayton, Ohio
| | - Aaron Madaris
- Department of Biomedical, Industrial, and Human Factors Engineering, College of Engineering and Computer Science, Wright State University , Dayton, Ohio
| | - Francisco J Alvarez
- Department of Neuroscience, Cell Biology and Physiology, Wright State University , Dayton, Ohio
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Praetorius J, Damkier HH. Transport across the choroid plexus epithelium. Am J Physiol Cell Physiol 2017; 312:C673-C686. [PMID: 28330845 DOI: 10.1152/ajpcell.00041.2017] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 03/17/2017] [Accepted: 03/17/2017] [Indexed: 11/22/2022]
Abstract
The choroid plexus epithelium is a secretory epithelium par excellence. However, this is perhaps not the most prominent reason for the massive interest in this modest-sized tissue residing inside the brain ventricles. Most likely, the dominant reason for extensive studies of the choroid plexus is the identification of this epithelium as the source of the majority of intraventricular cerebrospinal fluid. This finding has direct relevance for studies of diseases and conditions with deranged central fluid volume or ionic balance. While the concept is supported by the vast majority of the literature, the implication of the choroid plexus in secretion of the cerebrospinal fluid was recently challenged once again. Three newer and promising areas of current choroid plexus-related investigations are as follows: 1) the choroid plexus epithelium as the source of mediators necessary for central nervous system development, 2) the choroid plexus as a route for microorganisms and immune cells into the central nervous system, and 3) the choroid plexus as a potential route for drug delivery into the central nervous system, bypassing the blood-brain barrier. Thus, the purpose of this review is to highlight current active areas of research in the choroid plexus physiology and a few matters of continuous controversy.
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Affiliation(s)
- Jeppe Praetorius
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark; and
| | - Helle Hasager Damkier
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark; and.,Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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12
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Kaur C, Rathnasamy G, Ling EA. The Choroid Plexus in Healthy and Diseased Brain. J Neuropathol Exp Neurol 2016; 75:198-213. [DOI: 10.1093/jnen/nlv030] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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13
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Damkier HH, Brown PD, Praetorius J. Cerebrospinal Fluid Secretion by the Choroid Plexus. Physiol Rev 2013; 93:1847-92. [DOI: 10.1152/physrev.00004.2013] [Citation(s) in RCA: 291] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The choroid plexus epithelium is a cuboidal cell monolayer, which produces the majority of the cerebrospinal fluid. The concerted action of a variety of integral membrane proteins mediates the transepithelial movement of solutes and water across the epithelium. Secretion by the choroid plexus is characterized by an extremely high rate and by the unusual cellular polarization of well-known epithelial transport proteins. This review focuses on the specific ion and water transport by the choroid plexus cells, and then attempts to integrate the action of specific transport proteins to formulate a model of cerebrospinal fluid secretion. Significant emphasis is placed on the concept of isotonic fluid transport across epithelia, as there is still surprisingly little consensus on the basic biophysics of this phenomenon. The role of the choroid plexus in the regulation of fluid and electrolyte balance in the central nervous system is discussed, and choroid plexus dysfunctions are described in a very diverse set of clinical conditions such as aging, Alzheimer's disease, brain edema, neoplasms, and hydrocephalus. Although the choroid plexus may only have an indirect influence on the pathogenesis of these conditions, the ability to modify epithelial function may be an important component of future therapies.
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Affiliation(s)
- Helle H. Damkier
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark; and Faculty of Life Sciences, Michael Smith Building, Manchester University, Manchester, United Kingdom
| | - Peter D. Brown
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark; and Faculty of Life Sciences, Michael Smith Building, Manchester University, Manchester, United Kingdom
| | - Jeppe Praetorius
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark; and Faculty of Life Sciences, Michael Smith Building, Manchester University, Manchester, United Kingdom
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14
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Jo KD, Lee KS, Lee WT, Hur MS, Kim HJ. Expression of transient receptor potential channels in the ependymal cells of the developing rat brain. Anat Cell Biol 2013; 46:68-78. [PMID: 23560238 PMCID: PMC3615614 DOI: 10.5115/acb.2013.46.1.68] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 01/23/2013] [Accepted: 01/23/2013] [Indexed: 11/27/2022] Open
Abstract
Cerebrospinal fluid (CSF) plays an important role in providing brain tissue with a stable internal environment as well as in absorbing mechanical and thermal stresses. From its initial composition, derived from the amniotic fluid trapped by the closure of neuropores, CSF is modified by developing and differentiating ependymal cells lining the ventricular surface or forming the choroid plexus. Its osmolarity and ionic composition brings about a change through the action of many channels expressed on the ependymal cells. Some newly discovered transient receptor potential (TRP) channels are known to be expressed in the choroid plexus ependyma. To detect additional TRP channel expression, immunohistochemical screening was performed at the choroid plexus of 13-, 15-, 17-, and 19-day embryos, using antibodies against TRPV1, TRPV3, and TRPA1, and the expression was compared with those in the adult TRP channels. The level of TRP channel expression was higher in the choroid plexus which suggests more active functioning of TRP channels in the developing choroid plexus than the ventricular lining ependyma in the 15- and 17-day embryos. All the expression of TRP channels decreased at the 19th day of gestation. TRPA1 was expressed at a higher level than TRPV1 and TRPV3 in almost all stages in both the choroid plexus and ventricular lining epithelium. The highest level of TRPV1 and TRPV3 expression was observed in association with the glycogen deposits in the cytoplasm of the choroid plexus ependymal cells of the 15- and 17-day embryos.
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Affiliation(s)
- Kwang Deog Jo
- Department of Neurology, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea
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15
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Differential expression of Na+/H+-exchanger (NHE-1, 2, and 4) proteins and mRNA in rodent's uterus under sex steroid effect and at different phases of the oestrous cycle. BIOMED RESEARCH INTERNATIONAL 2013; 2013:840121. [PMID: 23509787 PMCID: PMC3582097 DOI: 10.1155/2013/840121] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 01/01/2013] [Indexed: 12/16/2022]
Abstract
Precise uterine fluid pH regulation may involve the Na+/H+-exchanger (NHE). We hypothesized that NHE isoforms are differentially expressed under different sex steroid treatment and at different oestrous cycle phases which may explain the uterine fluid pH changes observed under these conditions. Method. Oestrous cycle phases of intact WKY rats were identified by vaginal smear. Another group of rats was ovariectomized and treated with 0.2 μg 17β-oestradiol (E), 4 mg progesterone (P), and E followed by P (E + P). The animals were then sacrificed and the uteri were removed for mRNA and protein expression analyses by real-time PCR and western blotting, respectively. NHE isoforms distribution was detected by immunohistochemistry (IHC). Results. NHE-1 mRNA and protein were upregulated at diestrus (Ds) and following P treatment. Meanwhile, NHE-2 and NHE-4 proteins and mRNA were upregulated at proestrus (Ps) and estrus (Es) and following E treatment. NHE-1 was found predominantly at the apical membrane, while NHE-2 and NHE-4 were found at the apical and basolateral membranes of the luminal epithelia. NHE-4 is the main isoform upregulated by E. Conclusion. Differential expressions of uterine NHE isoforms 1, 2, and 4 could explain the observed changes in the uterine fluid pH under these conditions.
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Yurinskaya VE, Moshkov AV, Wibberley AV, Lang F, Model MA, Vereninov AA. Dual Response of Human Leukemia U937 Cells to Hypertonic Shrinkage: Initial Regulatory Volume Increase (RVI) and Delayed Apoptotic Volume Decrease (AVD). Cell Physiol Biochem 2012; 30:964-73. [DOI: 10.1159/000341473] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2012] [Indexed: 12/16/2022] Open
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17
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Lewis R, Feetham CH, Barrett-Jolley R. Cell volume regulation in chondrocytes. Cell Physiol Biochem 2011; 28:1111-22. [PMID: 22179000 DOI: 10.1159/000335847] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2011] [Indexed: 11/19/2022] Open
Abstract
Chondrocytes are the cells within cartilage which produce and maintain the extracellular matrix. Volume regulation in these cells is vital to their function and occurs in several different physiological and pathological contexts. Firstly, chondrocytes exist within an environment of changing osmolarity and compressive loads. Secondly, in osteoarthritic joint failure, cartilage water content changes and there is a notable increase in chondrocyte apoptosis. Thirdly, endochondral ossification requires chondrocyte swelling in association with hypertrophy. Regulatory volume decrease (RVD) and regulatory volume increase (RVI) have both been observed in articular chondrocytes and this review focuses on the mechanisms identified to account for these. There has been evidence so far to suggest TRPV4 is central to RVD; however other elements of the pathway have not yet been identified. Unlike RVD, RVI appears less robust in articular chondrocytes and there have been fewer mechanistic studies; the primary focus being on the Na(+)-K(+)-2Cl(-) co-transporter. The clinical significance of chondrocyte volume regulation remains unproven. Importantly however, transcript abundances of several ion channels implicated in volume control are changed in chondrocytes from osteoarthritic cartilage. A critical question is whether disturbances of volume regulation mechanisms lead to, result from or are simply coincidental to cartilage damage.
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Affiliation(s)
- Rebecca Lewis
- Department of Musculoskeletal Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, UK
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18
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Redzic Z. Molecular biology of the blood-brain and the blood-cerebrospinal fluid barriers: similarities and differences. Fluids Barriers CNS 2011; 8:3. [PMID: 21349151 PMCID: PMC3045361 DOI: 10.1186/2045-8118-8-3] [Citation(s) in RCA: 251] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Accepted: 01/18/2011] [Indexed: 01/11/2023] Open
Abstract
Efficient processing of information by the central nervous system (CNS) represents an important evolutionary advantage. Thus, homeostatic mechanisms have developed that provide appropriate circumstances for neuronal signaling, including a highly controlled and stable microenvironment. To provide such a milieu for neurons, extracellular fluids of the CNS are separated from the changeable environment of blood at three major interfaces: at the brain capillaries by the blood-brain barrier (BBB), which is localized at the level of the endothelial cells and separates brain interstitial fluid (ISF) from blood; at the epithelial layer of four choroid plexuses, the blood-cerebrospinal fluid (CSF) barrier (BCSFB), which separates CSF from the CP ISF, and at the arachnoid barrier. The two barriers that represent the largest interface between blood and brain extracellular fluids, the BBB and the BCSFB, prevent the free paracellular diffusion of polar molecules by complex morphological features, including tight junctions (TJs) that interconnect the endothelial and epithelial cells, respectively. The first part of this review focuses on the molecular biology of TJs and adherens junctions in the brain capillary endothelial cells and in the CP epithelial cells. However, normal function of the CNS depends on a constant supply of essential molecules, like glucose and amino acids from the blood, exchange of electrolytes between brain extracellular fluids and blood, as well as on efficient removal of metabolic waste products and excess neurotransmitters from the brain ISF. Therefore, a number of specific transport proteins are expressed in brain capillary endothelial cells and CP epithelial cells that provide transport of nutrients and ions into the CNS and removal of waste products and ions from the CSF. The second part of this review concentrates on the molecular biology of various solute carrier (SLC) transport proteins at those two barriers and underlines differences in their expression between the two barriers. Also, many blood-borne molecules and xenobiotics can diffuse into brain ISF and then into neuronal membranes due to their physicochemical properties. Entry of these compounds could be detrimental for neural transmission and signalling. Thus, BBB and BCSFB express transport proteins that actively restrict entry of lipophilic and amphipathic substances from blood and/or remove those molecules from the brain extracellular fluids. The third part of this review concentrates on the molecular biology of ATP-binding cassette (ABC)-transporters and those SLC transporters that are involved in efflux transport of xenobiotics, their expression at the BBB and BCSFB and differences in expression in the two major blood-brain interfaces. In addition, transport and diffusion of ions by the BBB and CP epithelium are involved in the formation of fluid, the ISF and CSF, respectively, so the last part of this review discusses molecular biology of ion transporters/exchangers and ion channels in the brain endothelial and CP epithelial cells.
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Affiliation(s)
- Zoran Redzic
- Department of Physiology, Faculty of Medicine, Kuwait University, SAFAT 13110, Kuwait.
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Damkier HH, Brown PD, Praetorius J. Epithelial pathways in choroid plexus electrolyte transport. Physiology (Bethesda) 2010; 25:239-49. [PMID: 20699470 DOI: 10.1152/physiol.00011.2010] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A stable intraventricular milieu is crucial for maintaining normal neuronal function. The choroid plexus epithelium produces the cerebrospinal fluid and in doing so influences the chemical composition of the interstitial fluid of the brain. Here, we review the molecular pathways involved in transport of the electrolytes Na+, K+, Cl-, and HCO3(-)across the choroid plexus epithelium.
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Affiliation(s)
- Helle H Damkier
- Department of Anatomy and the Water and Salt Research Center, Aarhus University, Aarhus C, Denmark
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