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Li BY, Gao YH, Pei JR, Yang YM, Zhang W, Sun DJ. ClC-7/Ostm1 contribute to the ability of tea polyphenols to maintain bone homeostasis in C57BL/6 mice, protecting against fluorosis. Int J Mol Med 2017; 39:1155-1163. [PMID: 28339032 PMCID: PMC5403613 DOI: 10.3892/ijmm.2017.2933] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 02/21/2017] [Indexed: 01/09/2023] Open
Abstract
Epidemiological investigations indicate that certain ingredients in tea bricks can antagonize the adverse effects of fluoride. Tea polyphenols (TPs), the most bioactive ingredient in tea bricks, have been demonstrated to be potent bone-supporting agents. ClC‑7 is known to be crucial for osteoclast (OC) bone resorption. Thus, in this study, we investigated the potential protective effects of TPs against fluorosis using a mouse model and explored the underlying mechanisms with particular focus on ClC‑7. A total of 40, healthy, 3‑week‑old male C57BL/6 mice were randomly divided into 4 groups (n=10/group) by weight as follows: distilled water (control group), 100 mg/l fluoridated water (F group), water containing 10 g/l TPs (TP group) and water containing 100 mg/l fluoride and 10 g/l TPs (F + TP group). After 15 weeks, and after the mice were sacrificed, the long bones were removed and bone marrow-derived macrophages were cultured ex vivo in order to perform several experiments. OCs were identified and counted by tartrate‑resistant acid phosphatase (TRAP) staining. The consumption of fluoride resulted in severe fluorosis and in an impaired OC function [impaired bone resorption, and a low mRNA expression of nuclear factor of activated T-cells 1 (NFATc1), ATPase H+ transporting V0 subunit D2 (ATP6v0d2) and osteopetrosis‑associated transmembrane protein 1 (Ostm1)]. In the F + TP group, fluorosis was attenuated and OC function was restored, but not the high bone fluoride content. Compared with the F group, mature OCs in the F + TP group expressed higher mRNA levels of ClC‑7 and Ostm1; the transportation and retaining of Cl‑ was improved, as shown by the fluorescence intensity experiment. On the whole, our findings indicate that TPs mitigate fluorosis in C57BL/6 mice by regulating OC bone resorption. Fluoride inhibits OC resorption by inhibiting ClC‑7 and Ostm1, whereas TPs attenuate this inhibitory effect of fluoride.
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Affiliation(s)
- Bing-Yun Li
- Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Yan-Hui Gao
- Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Jun-Rui Pei
- Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Yan-Mei Yang
- Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Wei Zhang
- Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Dian-Jun Sun
- Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
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Schedlbauer A, Gandini R, Kontaxis G, Paulmichl M, Furst J, Konrat R. The C-terminus of ICln is natively disordered but displays local structural preformation. Cell Physiol Biochem 2011; 28:1203-10. [PMID: 22179008 DOI: 10.1159/000335852] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2011] [Indexed: 11/19/2022] Open
Abstract
ICln is a vital, ubiquitously expressed protein with roles in cell volume regulation, angiogenesis, cell morphology, activation of platelets and RNA processing. In previous work we have determined the 3D structure of the N-terminus of ICln (residues 1-159), which folds into a PH-like domain followed by an unstructured region (residues H134 - Q159) containing protein-protein interaction sites. Here we present sequence-specific resonance assignments of the C-terminus (residues Q159 - H235) of ICln by NMR, and show that this region of the protein is intrinsically unstructured. By applying (13)Cα- (13)Cβ secondary chemical shifts to detect possible preferences for secondary structure elements we show that the C-terminus of ICln adopts a preferred α-helical organization between residues E170 and E187, and exists preferentially in extended conformations (β-strands) between residues D161 to Y168 and E217 to T223.
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Abstract
This article discusses three largely unrecognized aspects related to fluid movement in ocular tissues; namely, (a) the dynamic changes in water permeability observed in corneal and conjunctival epithelia under anisotonic conditions, (b) the indications that the fluid transport rate exhibited by the ciliary epithelium is insufficient to explain aqueous humor production, and (c) the evidence for fluid movement into and out of the lens during accommodation. We have studied each of these subjects in recent years and present an evaluation of our data within the context of the results of others who have also worked on electrolyte and fluid transport in ocular tissues. We propose that (1) the corneal and conjunctival epithelia, with apical aspects naturally exposed to variable tonicities, are capable of regulating their water permeabilities as part of the cell-volume regulatory process, (2) fluid may directly enter the anterior chamber of the eye across the anterior surface of the iris, thereby representing an additional entry pathway for aqueous humor production, and (3) changes in lens volume occur during accommodation, and such changes are best explained by a net influx and efflux of fluid.
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Affiliation(s)
- Oscar A Candia
- Department of Ophthalmology, Mount Sinai School of Medicine, New York, NY 10029, USA.
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Fürst J, Bottà G, Saino S, Dopinto S, Gandini R, Dossena S, Vezzoli V, Rodighiero S, Bazzini C, Garavaglia ML, Meyer G, Jakab M, Ritter M, Wappl-Kornherr E, Paulmichl M. The ICln interactome. Acta Physiol (Oxf) 2006; 187:43-9. [PMID: 16734741 DOI: 10.1111/j.1748-1716.2006.01549.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The many different functional phenotypes described in mammalian cells can only be explained by an intense interaction of the underlying proteins, substantiated by the fact that the number of independently expressed proteins in living cells seems not to exceed 25 K, a number way too small to explain the >250 K different phenotypes on a one-protein-one-function base. Therefore, the study of the interactome of the different proteins is of utmost importance. Here, we describe the present knowledge of the ICln interactome. ICln is a protein, we cloned and whose function was reported to be as divers as (i) ion permeation, (ii) cytoskeletal organization, and (iii) RNA processing. The role of ICln in these different functional modules can be described best as being a 'connector hub' with 'date hub' function.
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Affiliation(s)
- J Fürst
- Department of Physiology and Medical Physics, Innsbruck Medical University, Innsbruck, Austria
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Vessey JP, Shi C, Jollimore CA, Stevens KT, Coca-Prados M, Barnes S, Kelly ME. Hyposmotic activation of ICl,swell in rabbit nonpigmented ciliary epithelial cells involves increased ClC-3 trafficking to the plasma membrane. Biochem Cell Biol 2005; 82:708-18. [PMID: 15674438 DOI: 10.1139/o04-107] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In mammalian nonpigmented ciliary epithelial (NPE) cells, hyposmotic stimulation leading to cell swelling activates an outwardly rectifying Cl(-) conductance (I(Cl,swell)), which, in turn, results in regulatory volume decrease. The aim of this study was to determine whether increased trafficking of intracellular ClC-3 Cl channels to the plasma membrane could contribute to the I(Cl,swell) following hyposmotic stimulation. Our results demonstrate that hyposmotic stimulation reversibly activates an outwardly rectifying Cl(-) current that is inhibited by phorbol-12-dibutyrate and niflumic acid. Transfection with ClC-3 antisense, but not sense, oligonucleotides reduced ClC-3 expression as well as I(Cl,swell). Intracellular dialysis with 2 different ClC-3 antibodies abolished activation of I(Cl,swell). Immunofluorescence microscopy showed that hyposmotic stimulation increased ClC-3 immunoreactivity at the plasma membrane. To determine whether this increased expression of ClC-3 at the plasma membrane could be due to increased vesicular trafficking, we examined membrane dynamics with the fluorescent membrane dye FM1-43. Hyposmotic stimulation rapidly increased the rate of exocytosis, which, along with ICl,swell, was inhibited by the phosphoinositide-3-kinase inhibitor wortmannin and the microtubule disrupting agent, nocodazole. These findings suggest that ClC-3 channels contribute to I(Cl,swell) following hyposmotic stimulation through increased trafficking of channels to the plasma membrane.
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Affiliation(s)
- John P Vessey
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H 4H7, Canada
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Abstract
The four major sites for ocular water transport, the corneal epithelium and endothelium, the ciliary epithelium, and the retinal pigment epithelium, are reviewed. The cornea has an inherent tendency to swell, which is counteracted by its two surface cell layers, the corneal epithelium and endothelium. The bilayered ciliary epithelium secretes the aqueous humor into the posterior chamber, and the retinal pigment epithelium transports water from the retinal to the choroidal site. For each epithelium, ion transport mechanisms are associated with fluid transport, but the exact molecular coupling sites between ion and water transport remain undefined. In the retinal pigment epithelium, a H+-lactate cotransporter transports water. This protein could be the site of coupling between salt and water in this epithelium. The distribution of aquaporins does not suggest a role for these proteins in a general model for water transport in ocular epithelia. Some water-transporting membranes contain aquaporins, others do not. The ultrastructure is also variable among the cell layers and cannot be fitted into a general model. On the other hand, the direction of cotransport in symporters complies with the direction of fluid transport in both the corneal epi- and endothelium, as well as the ciliary epithelium and retinal pigment epithelium.
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Affiliation(s)
- Steffen Hamann
- Department of Medical Physiology, The Panum Institute, University of Copenhagen, Denmark
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Scandella E, Nagl UO, Oehl B, Bergmann F, Gschwentner M, Fürst J, Schmarda A, Ritter M, Waldegger S, Lang F, Deetjen P, Paulmichl M. The promoter for constitutive expression of the human ICln gene CLNS1A. J Biol Chem 2000; 275:15613-20. [PMID: 10821842 DOI: 10.1074/jbc.275.21.15613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ICln protein is expressed ubiquitously in mammals. Experiments designed to knock down the ICln protein in NIH 3T3 fibroblasts as well as in epithelial cells led to the conclusion that this protein is crucially involved in volume regulation after cytoplasmic swelling. Reconstitution of the ICln protein in lipid bilayers revealed the ion channel nature of ICln. Here we describe a new human promoter sequence, composed of 89 nucleotides, which is responsible for a highly constitutive expression of the ICln protein. The promoter sequence lacks a TATA box, and the transcription can be effected at multiple sites. In addition to the starting sites, upstream sequence elements are mandatory for an efficient transcription of the ICln gene (CLNS1A). These new nucleotide elements were defined by site-directed mutagenesis.
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Affiliation(s)
- E Scandella
- Department of Physiology, University of Innsbruck, Fritz-Pregl Strasse 3, A-6020 Innsbruck, Austria
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Abstract
We demonstrated previously that expression of rat pICln in Escherichia coli conferred a strong resistance to hypotonic stress. To define the intramolecular functional domain responsible for the resistance, molecular dissection of pICln was performed and the obtained peptides were expressed in E. coli. The cells expressing the peptides were exposed to a hypotonic solution, and their 'survival rates' were observed. The cells expressing only the peptides including the second acidic domain of pICln exhibited significantly higher 'survival rates' after hypotonic stress. The functional domain against hypotonicity was finally narrowed down to a peptide consisting of a 46-amino acid residue, P107-152. We conclude that the expression of P107-152 in E. coli cells could enhance their resistance to a hypotonic environment.
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Affiliation(s)
- G Z Tao
- Department-2 of Biochemistry, School of Medicine, Akita University, Hondo 1-1-1, Akita, 010-8543, Japan.
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Shi C, Ryan JS, French AS, Coca-Prados M, Kelly ME. Hyposmotically activated chloride channels in cultured rabbit non-pigmented ciliary epithelial cells. J Physiol 1999; 521 Pt 1:57-67. [PMID: 10562334 PMCID: PMC2269649 DOI: 10.1111/j.1469-7793.1999.00057.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. We used whole-cell patch-clamp recording techniques and noise analysis of whole-cell current to investigate the properties of hyposmotic shock (HOS)-activated Cl- channels in SV40-transformed rabbit non-pigmented ciliary epithelial (NPCE) cells. 2. Under conditions designed to isolate Cl- currents, exposure of cells to hyposmotic external solution reversibly increased the whole-cell conductance. 3. The whole-cell current activated with a slow time course (> 15 min), exhibited outward rectification and was Cl- selective. 4. The disulphonic stilbene derivatives 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS, 0.5 mM), 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS, 0. 5 mM) and 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS, 0.5 mM) produced a voltage-sensitive block of HOS-activated Cl- current at depolarized potentials, whereas niflumic acid produced a voltage-independent block of the current. 5. Under Ca2+-free conditions, HOS stimulation still reversibly activated the Cl- current, but the amplitude of current was reduced and the time course of current activation was slower compared with control (P < 0. 05). 6. The non-specific kinase inhibitor H-7 (100 microM), upregulated HOS-activated Cl- current amplitude in all cells tested (P < 0.05). 7. Noise analysis of whole-cell Cl- current indicated that cell swelling activated a high density of small conductance Cl- channels (< 1 pS). 8. We conclude that HOS primarily activates a high density of volume-sensitive small conductance Cl- channels in rabbit NPCE cells, and that Ca2+ and phosphorylation are involved in channel regulation.
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Affiliation(s)
- C Shi
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7
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Tao GZ, Kobayashi A, Itoh H, Tashima Y. Expression of pI(Cln) in Escherichia coli gives a strong tolerance to hypotonic stress. FEBS Lett 1998; 434:28-32. [PMID: 9738445 DOI: 10.1016/s0014-5793(98)00946-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We amplified the coding region DNA sequence from a rat renal pI(Cln) cDNA by PCR and expressed the protein in Escherichia coli cells. The cells were exposed to hypotonic conditions followed by spreading them onto LB plates for subsequent colony survival assay. The present study demonstrated that the cells expressing pI(Cln) exhibit a strong resistance to hypotonic stress. Moreover, the resistance was specifically inhibited by extracellular ATP and some anion channel inhibitors. These findings indicate that the expression of pI(Cln) directly confers tolerance to hypotonic stress, and pI(Cln) is concluded to be an important molecule for cell-volume regulation.
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Affiliation(s)
- G Z Tao
- Department-2 of Biochemistry, School of Medicine, Akita University, Japan
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