Structure and pharmacology of swelling‐sensitive chloride channels, I<sub>Cl,swell</sub>

Tassigny, Alexandra d'Anglemont de; Souktani, Rachid; Ghaleh, Bijan; Henry, Patrick; Berdeaux, Alain

doi:10.1046/j.1472-8206.2003.00197.x

Cited by 49 publications

(25 citation statements)

References 188 publications

(247 reference statements)

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“…S6) and found that channel activity was blocked in the presence of 100 µM of the potent chloride channel inhibitor, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), but was restored after washing out the inhibitor as expected [63, 64]. Channel activity was irreversibly blocked after application of 50 µM Gd 3+ , as expected for chloride channels [63,65]. The results indicate the presence of chloride channel proteins in giant proteoliposomes containing purified P-gp and agree with previous studies [64,66,67].…”

Section: Resultsmentioning

confidence: 95%

Hydrogel-assisted functional reconstitution of human P-glycoprotein (ABCB1) in giant liposomes

Horger

Liu

Rao

et al. 2015

Biochimica et Biophysica Acta (BBA) - Biomembranes

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This paper describes the formation of giant proteoliposomes containing P-glycoprotein (P-gp) from a solution of small proteoliposomes that had been deposited and partially dried on a film of agarose. This preparation method generated a significant fraction of giant proteoliposomes that were free of internalized vesicles, making it possible to determine the accessible liposome volume. Measuring the intensity of the fluorescent substrate rhodamine 123 (Rho123) inside and outside these giant proteoliposomes determined the concentration of transported substrates of P-gp. Fitting a kinetic model to the fluorescence data revealed the rate of passive diffusion as well as active transport by reconstituted P-gp in the membrane. This approach determined estimates for the membrane permeability coefficient (Ps) of passive diffusion and rate constants of active transport (kT) by P-gp as a result of different experimental conditions. The Ps value for Rho123 was larger in membranes containing P-gp under all assay conditions than in membranes without P-gp indicating increased leakiness in the presence of reconstituted transmembrane proteins. For P-gp liposomes, the kT value was significantly higher in the presence of ATP than in its absence or in the presence of ATP and the competitive inhibitor verapamil. This difference in kT values verified that P-gp was functionally active after reconstitution and quantified the rate of active transport. Lastly, patch clamp experiments on giant proteoliposomes showed ion channel activity consistent with a chloride ion channel protein that co-purified with P-gp. Together, these results demonstrate several advantages of using giant rather than small proteoliposomes to characterize transport properties of transport proteins and ion channels.

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Section: Resultsmentioning

confidence: 95%

Hydrogel-assisted functional reconstitution of human P-glycoprotein (ABCB1) in giant liposomes

Horger

Liu

Rao

et al. 2015

Biochimica et Biophysica Acta (BBA) - Biomembranes

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“…CAAC is the one of very few channels for which a cDNA has not yet been unequivocally identified (d’Anglemont de Tassigny et al, 2003; Eggermont, 2004). To identify the genes encoding CAAC channels in astrocytes, we performed reverse transcriptase polymerase chain reaction (RT-PCR) with primer sets for various CAAC candidate genes such as Cl − channel-Calcium Activated ( CLCA) , Drosophila tweety homolog (Ttyh) , and bestrophin (Best) family genes (Eggermont, 2004; Suzuki and Mizuno, 2004).…”

Section: Resultsmentioning

confidence: 99%

Bestrophin-1 Encodes for the Ca²⁺-Activated Anion Channel in Hippocampal Astrocytes

Park¹,

Oh²,

Han³

et al. 2009

J. Neurosci.

121

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In mammalian brain, neurons and astrocytes are reported to express various chloride and anion channels, but the evidence for functional expression of Ca 2ϩ -activated anion channel (CAAC) and its molecular identity have been lacking. Here we report electrophysiological evidence for the CAAC expression and its molecular identity by mouse Bestrophin 1 (mBest1) in astrocytes of the mouse brain. Using Ca 2ϩ imaging and perforated-patch-clamp analysis, we demonstrate that astrocytes displayed an inward current at holding potential of Ϫ70 mV that was dependent on an increase in intracellular Ca 2ϩ after G ␣q -coupled receptor activation. This current was mediated mostly by anions and was sensitive to well known anion channel blockers such as niflumic acid, 5-nitro-2(3-phenylpropylamino)-benzoic acid, and flufenamic acid. To find the molecular identity of the anion channel responsible for the CAAC current, we analyzed the expression of candidate genes and found that the mRNA for mouse mBest1 is predominantly expressed in acutely dissociated or cultured astrocytes. Whole-cell patch-clamp analysis using HEK293T cells heterologously expressing full-length mBest1 showed a Ca 2ϩ -dependent current mediated by mBest1, with a complete impairment of the current by a putative pore mutation, W93C. Furthermore, mBest1-mediated CAAC from cultured astrocytes was significantly reduced by expression of mBest1-specific short hairpin RNA (shRNA), suggesting that the CAAC is mediated by a channel encoded by mBest1. Finally, hippocampal CA1 astrocytes in hippocampal slice also showed mBest1-mediated CAAC because it was inhibited by mBest1-specific shRNA. Collectively, these data provide molecular evidence that the mBest1 channel is responsible for CAAC function in astrocytes.

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“…A primary role of plasma membrane Cl - channels in non-excitable cells is in the volume-regulatory response to cell volume perturbation [72,73]. It is likely that within the relatively sheltered environment of the host cytoplasm, the parasite is not exposed to significant permutations in osmolarity and that it therefore does not require Cl - channels for this purpose.…”

Section: Discussionmentioning

confidence: 99%

The 'permeome' of the malaria parasite: an overview of the membrane transport proteins of Plasmodium falciparum

et al. 2005

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Background: The uptake of nutrients, expulsion of metabolic wastes and maintenance of ion homeostasis by the intraerythrocytic malaria parasite is mediated by membrane transport proteins. Proteins of this type are also implicated in the phenomenon of antimalarial drug resistance. However, the initial annotation of the genome of the human malaria parasite Plasmodium falciparum identified only a limited number of transporters, and no channels. In this study we have used a combination of bioinformatic approaches to identify and attribute putative functions to transporters and channels encoded by the malaria parasite, as well as comparing expression patterns for a subset of these.

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Structure and pharmacology of swelling‐sensitive chloride channels, I_Cl,swell

Cited by 49 publications

References 188 publications

Hydrogel-assisted functional reconstitution of human P-glycoprotein (ABCB1) in giant liposomes

Hydrogel-assisted functional reconstitution of human P-glycoprotein (ABCB1) in giant liposomes

Bestrophin-1 Encodes for the Ca²⁺-Activated Anion Channel in Hippocampal Astrocytes

The 'permeome' of the malaria parasite: an overview of the membrane transport proteins of Plasmodium falciparum

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Structure and pharmacology of swelling‐sensitive chloride channels, ICl,swell

Cited by 49 publications

References 188 publications

Hydrogel-assisted functional reconstitution of human P-glycoprotein (ABCB1) in giant liposomes

Hydrogel-assisted functional reconstitution of human P-glycoprotein (ABCB1) in giant liposomes

Bestrophin-1 Encodes for the Ca2+-Activated Anion Channel in Hippocampal Astrocytes

The 'permeome' of the malaria parasite: an overview of the membrane transport proteins of Plasmodium falciparum

Contact Info

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Structure and pharmacology of swelling‐sensitive chloride channels, I_Cl,swell

Bestrophin-1 Encodes for the Ca²⁺-Activated Anion Channel in Hippocampal Astrocytes