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Int J Mol Sci
2018 Mar 02;193:. doi: 10.3390/ijms19030719.
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Expression of LRRC8/VRAC Currents in Xenopus Oocytes: Advantages and Caveats.
Gaitán-Peñas H
,
Pusch M
,
Estévez R
.
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Volume-regulated anion channels (VRACs) play a role in controlling cell volume by opening upon cell swelling. Apart from controlling cell volume, their function is important in many other physiological processes, such as transport of metabolites or drugs, and extracellular signal transduction. VRACs are formed by heteromers of the pannexin homologous protein LRRC8A (also named Swell1) with other LRRC8 members (B, C, D, and E). LRRC8 proteins are difficult to study, since they are expressed in all cells of our body, and the channel stoichiometry can be changed by overexpression, resulting in non-functional heteromers. Two different strategies have been developed to overcome this issue: complementation by transient transfection of LRRC8 genome-edited cell lines, and reconstitution in lipid bilayers. Alternatively, we have used Xenopus oocytes as a simple system to study LRRC8 proteins. Here, we have reviewed all previous experiments that have been performed with VRAC and LRRC8 proteins in Xenopus oocytes. We also discuss future strategies that may be used to perform structure-function analysis of the VRAC in oocytes and other systems, in order to understand its role in controlling multiple physiological functions.
Figure 1
Functional expression of LRRC8-mediated VRAC currents in Xenopus oocytes. Currents of single oocytes co-injected with 8A/8E or 8A-VFP/8E-mCherry in response to an iv-pulse protocol in isotonic conditions (Iso) or after a 5 min perfusion with a hypotonic solution (Hypo). On the right, we show the scheme for the injected LRRC8 proteins.
Figure 2
Biochemical and functional analyses of the currents induced by the expression of 8E-mCherry in Xenopus oocytes. (A) Time course between 2 and 4 days after oocyte injection of the mean values of currents at 60 mV for uninjected oocytes (n ≥ 7), oocytes injected with 8E-mCherry (n ≥ 18), and oocytes injected with 8A-VFP/8E-mCherry (n ≥ 7). Data are from at least two different injections and indicate the mean ± SEM; (B) Western blots against some LRRC8 proteins, using β-tubulin as a loading control. We used protein extracts of (from left to right): collagenase-treated uninjected oocytes “C Un-inj” and oocytes injected with 8A or 8D “hum 8A/8D inj”. Three independent Western-blot experiments to detect Xenopus LRRC8A and two WB experiments to detect Xenopus LRRC8D gave similar results; (C) Comparison of the mean values of current at 60 mV between uninjected oocytes (n = 4) and oocytes co-expressing 8E-mCherry (20 ng of complimentary ribonucleic acid (cRNA)) plus 10 ng of an oligonucleotide sense “x8A sense” (n = 5 at day 3, n = 5 at day 4) or plus 10 ng of an oligo antisense “x8A Asense” (n = 4 at day 3, n = 5 at day 4). Data indicate the mean ± SEM * p < 0.05, ** p < 0.01, *** p < 0.001. Another injection gave similar results.
Figure 3
Surface analysis of LRRC8 proteins expressed in Xenopus oocytes. Surface expression was examined using a chemiluminescence technique detecting the HA epitope inserted into the first extracellular loop (HAloop) already described [51]. The sequence of LRRC8A with the HA tag was CLPCKWYPYDVPDYAVTKDSC and the sequence of LRRC8E with the HA tag was CLPNHEYPYDVPDYALQENLS (HA tag in italics). The HA tag did not interfere with the proper function of the proteins. In the panel on the left, we show the membrane levels of 8A-VFP, and in the other panel, the levels of 8E-mCherry. We show here a typical experiment with n = 15, 15, and 10 oocytes for the panel on the left, and n = 8, 15, and 9 for the panel on the right.
Figure 1. Functional expression of LRRC8-mediated VRAC currents in Xenopus oocytes. Currents of single oocytes co-injected with 8A/8E or 8A-VFP/8E-mCherry in response to an iv-pulse protocol in isotonic conditions (Iso) or after a 5 min perfusion with a hypotonic solution (Hypo). On the right, we show the scheme for the injected LRRC8 proteins.
Figure 2. Biochemical and functional analyses of the currents induced by the expression of 8E-mCherry in Xenopus oocytes. (A) Time course between 2 and 4 days after oocyte injection of the mean values of currents at 60 mV for uninjected oocytes (n ≥ 7), oocytes injected with 8E-mCherry (n ≥ 18), and oocytes injected with 8A-VFP/8E-mCherry (n ≥ 7). Data are from at least two different injections and indicate the mean ± SEM; (B) Western blots against some LRRC8 proteins, using β-tubulin as a loading control. We used protein extracts of (from left to right): collagenase-treated uninjected oocytes “C Un-inj” and oocytes injected with 8A or 8D “hum 8A/8D inj”. Three independent Western-blot experiments to detect Xenopus LRRC8A and two WB experiments to detect Xenopus LRRC8D gave similar results; (C) Comparison of the mean values of current at 60 mV between uninjected oocytes (n = 4) and oocytes co-expressing 8E-mCherry (20 ng of complimentary ribonucleic acid (cRNA)) plus 10 ng of an oligonucleotide sense “x8A sense” (n = 5 at day 3, n = 5 at day 4) or plus 10 ng of an oligo antisense “x8A Asense” (n = 4 at day 3, n = 5 at day 4). Data indicate the mean ± SEM * p < 0.05, ** p < 0.01, *** p < 0.001. Another injection gave similar results.
Figure 3. Surface analysis of LRRC8 proteins expressed in Xenopus oocytes. Surface expression was examined using a chemiluminescence technique detecting the HA epitope inserted into the first extracellular loop (HAloop) already described [51]. The sequence of LRRC8A with the HA tag was CLPCKWYPYDVPDYAVTKDSC and the sequence of LRRC8E with the HA tag was CLPNHEYPYDVPDYALQENLS (HA tag in italics). The HA tag did not interfere with the proper function of the proteins. In the panel on the left, we show the membrane levels of 8A-VFP, and in the other panel, the levels of 8E-mCherry. We show here a typical experiment with n = 15, 15, and 10 oocytes for the panel on the left, and n = 8, 15, and 9 for the panel on the right.
Abascal,
LRRC8 proteins share a common ancestor with pannexins, and may form hexameric channels involved in cell-cell communication.
2012, Pubmed
Abascal,
LRRC8 proteins share a common ancestor with pannexins, and may form hexameric channels involved in cell-cell communication.
2012,
Pubmed
Ackerman,
Hypotonicity activates a native chloride current in Xenopus oocytes.
1994,
Pubmed
,
Xenbase
Ahring,
Concatenated nicotinic acetylcholine receptors: A gift or a curse?
2018,
Pubmed
,
Xenbase
Arellano,
Functional role of follicular cells in the generation of osmolarity-dependent Cl- currents in Xenopus follicles.
1995,
Pubmed
,
Xenbase
Benfenati,
Carbenoxolone inhibits volume-regulated anion conductance in cultured rat cortical astroglia.
2009,
Pubmed
Beyer,
Gap junction structure: unraveled, but not fully revealed.
2017,
Pubmed
Blumenthal,
The minK potassium channel exists in functional and nonfunctional forms when expressed in the plasma membrane of Xenopus oocytes.
1994,
Pubmed
,
Xenbase
Buyse,
Expression of human pICln and ClC-6 in Xenopus oocytes induces an identical endogenous chloride conductance.
1997,
Pubmed
,
Xenbase
Chillarón,
An intracellular trafficking defect in type I cystinuria rBAT mutants M467T and M467K.
1997,
Pubmed
,
Xenbase
Choe,
Crystal structure of human toll-like receptor 3 (TLR3) ectodomain.
2005,
Pubmed
Dascal,
The use of Xenopus oocytes for the study of ion channels.
1987,
Pubmed
,
Xenbase
Davidson,
Glycyrrhetinic acid derivatives: a novel class of inhibitors of gap-junctional intercellular communication. Structure-activity relationships.
1988,
Pubmed
Decher,
DCPIB is a novel selective blocker of I(Cl,swell) and prevents swelling-induced shortening of guinea-pig atrial action potential duration.
2001,
Pubmed
,
Xenbase
Dourado,
Pannexin-1 is blocked by its C-terminus through a delocalized non-specific interaction surface.
2014,
Pubmed
Eertmoed,
Transient expression of heteromeric ion channels.
1998,
Pubmed
Engelhardt,
Effects on channel properties and induction of cell death induced by c-terminal truncations of pannexin1 depend on domain length.
2015,
Pubmed
,
Xenbase
Estévez,
The amino acid transport system y+L/4F2hc is a heteromultimeric complex.
1998,
Pubmed
,
Xenbase
Friard,
Comparative Effects of Chloride Channel Inhibitors on LRRC8/VRAC-Mediated Chloride Conductance.
2017,
Pubmed
Gaitán-Peñas,
Investigation of LRRC8-Mediated Volume-Regulated Anion Currents in Xenopus Oocytes.
2016,
Pubmed
,
Xenbase
Galietta,
Green fluorescent protein-based halide indicators with improved chloride and iodide affinities.
2001,
Pubmed
Ghosh,
Leucine-rich repeat-containing 8B protein is associated with the endoplasmic reticulum Ca2+ leak in HEK293 cells.
2017,
Pubmed
Gradogna,
Cisplatin activates volume sensitive LRRC8 channel mediated currents in Xenopus oocytes.
2017,
Pubmed
,
Xenbase
Gradogna,
Subunit-dependent oxidative stress sensitivity of LRRC8 volume-regulated anion channels.
2017,
Pubmed
,
Xenbase
Hammer,
A Coding Variant of ANO10, Affecting Volume Regulation of Macrophages, Is Associated with Borrelia Seropositivity.
2015,
Pubmed
,
Xenbase
Hartzell,
Activation of different Cl currents in Xenopus oocytes by Ca liberated from stores and by capacitative Ca influx.
1996,
Pubmed
,
Xenbase
Hoffmann,
Physiology of cell volume regulation in vertebrates.
2009,
Pubmed
Hyzinski-García,
LRRC8A protein is indispensable for swelling-activated and ATP-induced release of excitatory amino acids in rat astrocytes.
2014,
Pubmed
Jentsch,
VRACs and other ion channels and transporters in the regulation of cell volume and beyond.
2016,
Pubmed
Jentsch,
VRAC: molecular identification as LRRC8 heteromers with differential functions.
2016,
Pubmed
Jeworutzki,
GlialCAM, a CLC-2 Cl(-) channel subunit, activates the slow gate of CLC chloride channels.
2014,
Pubmed
,
Xenbase
Jordt,
Molecular dissection of gating in the ClC-2 chloride channel.
1997,
Pubmed
,
Xenbase
Lee,
The protein synthesis inhibitor blasticidin s enters mammalian cells via leucine-rich repeat-containing protein 8D.
2014,
Pubmed
Lutter,
Selective transport of neurotransmitters and modulators by distinct volume-regulated LRRC8 anion channels.
2017,
Pubmed
Manolopoulos,
Swelling-activated efflux of taurine and other organic osmolytes in endothelial cells.
1997,
Pubmed
Mazzaferro,
α4β2 Nicotinic Acetylcholine Receptors: RELATIONSHIPS BETWEEN SUBUNIT STOICHIOMETRY AND FUNCTION AT THE SINGLE CHANNEL LEVEL.
2017,
Pubmed
Mongin,
Volume-regulated anion channel--a frenemy within the brain.
2016,
Pubmed
Nilius,
Properties of volume-regulated anion channels in mammalian cells.
1997,
Pubmed
Oshima,
Structure of an innexin gap junction channel and cryo-EM sample preparation.
2017,
Pubmed
Pasantes-Morales,
Brain volume regulation: osmolytes and aquaporin perspectives.
2010,
Pubmed
Pedersen,
The identification of a volume-regulated anion channel: an amazing Odyssey.
2015,
Pubmed
Pedersen,
Biophysics and Physiology of the Volume-Regulated Anion Channel (VRAC)/Volume-Sensitive Outwardly Rectifying Anion Channel (VSOR).
2016,
Pubmed
Penuela,
The biochemistry and function of pannexin channels.
2013,
Pubmed
Planells-Cases,
Subunit composition of VRAC channels determines substrate specificity and cellular resistance to Pt-based anti-cancer drugs.
2015,
Pubmed
Preston,
Appearance of water channels in Xenopus oocytes expressing red cell CHIP28 protein.
1992,
Pubmed
,
Xenbase
Qiu,
SWELL1, a plasma membrane protein, is an essential component of volume-regulated anion channel.
2014,
Pubmed
Sabirov,
The organic anion transporter SLCO2A1 constitutes the core component of the Maxi-Cl channel.
2017,
Pubmed
Sandilos,
Pannexin 1, an ATP release channel, is activated by caspase cleavage of its pore-associated C-terminal autoinhibitory region.
2012,
Pubmed
Sandilos,
Physiological mechanisms for the modulation of pannexin 1 channel activity.
2012,
Pubmed
Sawada,
A congenital mutation of the novel gene LRRC8 causes agammaglobulinemia in humans.
2003,
Pubmed
Schober,
Molecular composition and heterogeneity of the LRRC8-containing swelling-activated osmolyte channels in primary rat astrocytes.
2017,
Pubmed
Schroeder,
Expression cloning of TMEM16A as a calcium-activated chloride channel subunit.
2008,
Pubmed
,
Xenbase
Soreq,
Xenopus oocyte microinjection: from gene to protein.
1992,
Pubmed
,
Xenbase
Stauber,
The volume-regulated anion channel is formed by LRRC8 heteromers – molecular identification and roles in membrane transport and physiology.
2015,
Pubmed
Stotz,
Anion-sensitive fluorophore identifies the Drosophila swell-activated chloride channel in a genome-wide RNA interference screen.
2012,
Pubmed
Syeda,
LRRC8 Proteins Form Volume-Regulated Anion Channels that Sense Ionic Strength.
2016,
Pubmed
Teijido,
Localization and functional analyses of the MLC1 protein involved in megalencephalic leukoencephalopathy with subcortical cysts.
2004,
Pubmed
,
Xenbase
Ulbrich,
Subunit counting in membrane-bound proteins.
2007,
Pubmed
,
Xenbase
Ullrich,
Inactivation and Anion Selectivity of Volume-regulated Anion Channels (VRACs) Depend on C-terminal Residues of the First Extracellular Loop.
2016,
Pubmed
Voets,
The chloride current induced by expression of the protein pICln in Xenopus oocytes differs from the endogenous volume-sensitive chloride current.
1996,
Pubmed
,
Xenbase
Voss,
Identification of LRRC8 heteromers as an essential component of the volume-regulated anion channel VRAC.
2014,
Pubmed