Chloride channels in the plasma membrane of a foetal Drosophila cell line, S2

Asmild, Margit; Willumsen, Niels J.

doi:10.1007/s004240000252

Cited by 5 publications

(5 citation statements)

References 12 publications

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“…In mammals, ClC-1 is found in mammalian skeletal muscle, and its functional destruction leads to myotonia (Steinmeyer et al, 1991). Voltage-dependent chloride channels are found in Drosophila neurons (Yamamoto and Suzuki, 1987), Drosophila S2 fetal cells (Asmild and Willumsen, 2000), and C. elegans (Schriever et al, 1999), although there is currently no designation of Drosophila channels using the ClC nomenclature. The involvement of these channels in a number of critical physiological processes suggests that they may be exploitable as insecticide target sites, especially if insect or nematode subtypes exist that are absent in mammals or have a structure different from their mammalian homologs.…”

Section: Voltage-gated Chloride Channel Structure and Functionmentioning

confidence: 99%

Chloride channels as tools for developing selective insecticides

Bloomquist

2003

Arch Insect Biochem Physiol

242

113

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Ligand-gated chloride channels underlie inhibition in excitable membranes and are proven target sites for insecticides. The gamma-aminobutyric acid (GABA(1)) receptor/chloride ionophore complex is the primary site of action for a number of currently used insecticides, such as lindane, endosulfan, and fipronil. These compounds act as antagonists by stabilizing nonconducting conformations of the chloride channel. Blockage of the GABA-gated chloride channel reduces neuronal inhibition, which leads to hyperexcitation of the central nervous system, convulsions, and death. We recently investigated the mode of action of the silphinenes, plant-derived natural compounds that structurally resemble picrotoxinin. These materials antagonize the action of GABA on insect neurons and block GABA-mediated chloride uptake into mouse brain synaptoneurosomes in a noncompetitive manner. In mammals, avermectins have a blocking action on the GABA-gated chloride channel consistent with a coarse tremor, whereas at longer times and higher concentrations, activation of the channel suppresses neuronal activity. Invertebrates display ataxia, paralysis, and death as the predominant signs of poisoning, with a glutamate-gated chloride channel playing a major role. Additional target sites for the avermectins or other chloride channel-directed compounds might include receptors gated by histamine, serotonin, or acetylcholine.The voltage-sensitive chloride channels form another large gene family of chloride channels. Voltage-dependent chloride channels are involved in a number of physiological processes including: maintenance of electrical excitability, chloride ion secretion and resorption, intravesicular acidification, and cell volume regulation. A subset of these channels is affected by convulsants and insecticides in mammals, although the role they play in acute lethality in insects is unclear. Given the wide range of functions that they mediate, these channels are also potential targets for insecticide development.

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Section: Voltage-gated Chloride Channel Structure and Functionmentioning

confidence: 99%

Chloride channels as tools for developing selective insecticides

Bloomquist

2003

Arch Insect Biochem Physiol

242

113

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“…To test this idea we applied whole-cell electrophysiology methods to determine whether addition of dsRNA to SID-1 expressing Drosophila S2 cells would result in a measurable change in membrane conductance. We first established and verified a whole-cell patch connection by measuring the activity of an endogenous Cl À channel in Drosophila S2 cells (Asmild and Willumsen 2000). We then measured the change in current and membrane conductance of voltage clamped cells following the addition of 500-base pair (bp) dsRNA to the bath solution (for voltage ramp and current response, see Supplemental Fig.…”

Section: Sid-1 Is Activated By Dsrnamentioning

confidence: 99%

SID-1 is a dsRNA-selective dsRNA-gated channel

Shih¹,

Hunter²

2011

RNA

197

156

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Systemic RNAi in Caenorhabditis elegans requires the widely conserved transmembrane protein SID-1 to transport RNAi silencing signals between cells. When expressed in Drosophila S2 cells, C. elegans SID-1 enables passive dsRNA uptake from the culture medium, suggesting that SID-1 functions as a channel for the transport of double-stranded RNA (dsRNA). Here we show that nucleic acid transport by SID-1 is specific for dsRNA and that addition of dsRNA to SID-1 expressing cells results in changes in membrane conductance, which indicate that SID-1 is a dsRNA gated channel protein. Consistent with passive bidirectional transport, we find that the RNA induced silencing complex (RISC) is required to prevent the export of imported dsRNA and that retention of dsRNA by RISC does not seem to involve processing of retained dsRNA into siRNAs. Finally, we show that mimics of natural molecules that contain both single-and double-stranded dsRNA, such as hairpin RNA and pre-microRNA, can be transported by SID-1. These findings provide insight into the nature of potential endogenous RNA signaling molecules in animals.

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“…Previous studies suggest that Drosophila S2 cells do not have an endogenous Ca 2ϩ -activated conductance (17,18). As shown in the representative current trace in Figure 3A, DmPC2 expression produced a novel population of Ca 2ϩ -activated channels in excised inside-out patches.…”

Section: Expression Of Dmpc2 Yields Novel Ca 2ϩ -Activated Currentmentioning

confidence: 87%

Evolutionary Conservation of Drosophila Polycystin-2 as a Calcium-Activated Cation Channel

Venglarik

Gao

2004

Journal of the American Society of Nephrology

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Abstract. Mutations in the PKD2 gene cause autosomal dominant polycystic kidney disease (ADPKD) in humans. The protein encoded by PKD2 has similarity to voltage-sensitive cation channels and TRP channels and was named polycystin-2 (PC2). In agreement with this structural information, expression of PC2 in Xenopus oocytes or reconstitution of human PC2 in planar lipid bilayers produced Ca 2ϩ -activated cation channels. Although these studies provided a basic description of the biophysical, regulatory, and pharmacologic properties of the PC2-induced channels, it is still unknown how defective PC2 activity leads to cyst formation and expansion in ADPKD patients. To establish a genetic model for studying PC2 function and regulation, the authors identified and cloned a Drosophila PC2 (DmPC2). It is here shown that expression of DmPKD2 in Drosophila S2 cells produced a novel channel. On the basis of the similarity of this channel's properties to mammalian PKD2-induced channels, this Drosophila channel is expected to provide a convenient genetic model for dissecting the mechanisms underlying ADPKD.Polycystin-2 (PC2) is an approximately 110 kD transmembrane protein having sequence and structural similarities to voltagedependent cation channels and TRP channels (1,2). Mutations in the PKD2 gene that encodes PC2 cause autosomal dominant polycystic kidney disease (ADPKD). This genetic disorder occurs at a frequency of 1:400 to 1:1000 (3) and is characterized by large fluid-filled cysts in the kidney and other target organs (4,5). The formation and expansion of cysts progressively destroys the normal parenchyma and often causes end-stage renal failure, requiring transplant or dialysis (3,5).Heterologous expression of human PC2 after injection of Xenopus oocytes with PKD2 cDNA introduced novel nonselective cation channels in the plasma membrane and endoplasmic reticulum (6). These channels conducted both monovalent and divalent cations (Na , or amiloride were shown to inhibit current (6,8,9).Although previous studies demonstrate that PC2 likely functions as a calcium-activated cation channel and provide a basic description of its properties, many important questions remain unanswered regarding the upstream mediators that are responsible for regulating channel function and the downstream signaling pathways that normally serve to prevent cyst formation. In one study, PC2 was shown to localize to the endoplasmic reticulum of renal epithelial cells, and expression of PC2 in LLC-PK 1 kidney cells enhanced vasopressin-induced intracellular Ca 2ϩ release (10). In a subsequent study, PC2 was localized on the primary cilium of renal epithelia and appeared to mediate Ca 2ϩ influx in response to changes in apical fluid flow (11,12). Additional information is needed to understand the relative importance of these divergent observations and to identify the mechanisms underlying ADPKD.As many signaling mechanisms are conserved throughout phylogeny, one possible means of elucidating the PC2-mediated regulatory pathways is to use Drosophila a...

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Chloride channels in the plasma membrane of a foetal Drosophila cell line, S2

Cited by 5 publications

References 12 publications

Chloride channels as tools for developing selective insecticides

Chloride channels as tools for developing selective insecticides

SID-1 is a dsRNA-selective dsRNA-gated channel

Evolutionary Conservation of Drosophila Polycystin-2 as a Calcium-Activated Cation Channel

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