GTPγS-Induced Ca2+ Activated Cl− Currents: Its Stable Induction by Gqα Overexpression in Xenopus Oocytes

Kaibara, Muneshige; Nagase, Yoshihisa; Murasaki, Osamu; Uezono, Yasuhito; Doi, Yoshiyuki; Taniyama, Kohtaro

doi:10.1254/jjp.86.244

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…Moreover, EGTA at the estimated intra-oocyte concentration of 5 mmol/L failed to reduce 36 Cl − influx (k = 0.0041 ± 0.0002) (N = 8) compared to that in the absence of EGTA (k = 0.0042 ± 0.0005) (N = 7). This contrasted to inhibition by injected EGTA of oocyte Cl − current stimulated by Ca 2+ ionophore A23187 [35][36][37], lysophosphatidic acid or sphingosine-1-phosphate [38], constitutively activated Ga Q [37], or by mechanosensitive Ca 2+ entry [39]. EGTA at this concentration reduced resting cytosolic [Ca 2+ ] in Fura2-loaded oocytes from 79 ± 1 nmol/L to 65 ± 1 nmol/L.…”

Section: Cd167-pkd1 (115-226)-activated CL − Flux Includes a Conductmentioning

confidence: 94%

Expression of the polycystin-1 C-terminal cytoplasmic tail increases Cl- channel activity in Xenopus oocytes

Chernova¹,

Vandorpe²,

Clark³

et al. 2005

Kidney International

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Expression of the polycystin-1 C-terminal cytoplasmic tail increases Cl(-) channel activity in Xenopus oocytes. Background. Cyst expansion in autosomal-dominant polycystic kidney disease (ADPKD) is characterized by active Cl(-) secretion in excess of solute reabsorption. However, the connections between elevated epithelial Cl(-) secretion and loss-of-function or dysregulation of either ADPKD gene polycystin-1 (PC1) or polycystin-2 (PC2) remain little understood. Methods. Cl(-) transport in Xenopus oocytes expressing the CD16.7-PKD1 (115-226) fusion protein containing the final 112 amino acid (aa) of the PC1 C-terminal cytoplasmic tail, or in oocytes expressing related PC1 fusion protein mutants, was studied by isotopic flux, two-electrode voltage clamp, and outside-out patch clamp recording. Results. Expression in oocytes of CD16.7-PKD1 (115-226) increased rates of both influx and efflux of (36)Cl(-), whereas CD16.7-PKD1 (1-92) containing the initial 92 aa of the PC1 C-terminal cytoplasmic tail was inactive. The increased Cl(-) transport resembled CD16.7-PKD1 (115-226)-stimulated cation current in its sensitivity to ADPKD-associated missense mutations, to mutations in phosphorylation sites, and to mutations within or encroaching upon the PC1 coiled-coil domain, as well as in its partial suppression by coexpressed PC2. The NS3623- and 4, 4'-diisothiocyanatostilbene-2, 2'-disulfonic acid (DIDS)-sensitive (36)Cl(-) flux was not blocked by injected ethyleneglycol tetraacetate (EGTA) or by the cation channel inhibitor SKF96365, and was stimulated by the cation channel inhibitor La(3+), suggesting that CD16.7-PKD1 (115-226)-associated cation conductance was not required for (36)CI(-) flux activation. Outside-out patches from oocytes expressing CD16.7-PKD1 (115-226) also exhibited increased NS3623-sensitive Cl(-) current. Conclusion. These data show that CD16.7-PKD1 (115-226) activates Cl(-) channels in the Xenopus oocyte plasma membrane in parallel with, but not secondary to, activation of Ca(2+)-permeable cation channels.

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Section: Cd167-pkd1 (115-226)-activated CL − Flux Includes a Conductmentioning

confidence: 94%

Expression of the polycystin-1 C-terminal cytoplasmic tail increases Cl- channel activity in Xenopus oocytes

Chernova¹,

Vandorpe²,

Clark³

et al. 2005

Kidney International

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“…As previously reported, oocytes overexpressing Gq␣ are a useful system for studying the functional role of Gq␣ in regulating cellular events (Kaibara et al, 2001). To study effects of Fig.…”

Section: Electrophysiological Studies Using Xenopus Oocytesmentioning

confidence: 81%

“…If activation of the current with the injection of GTP␥S results from nonspecific activation of G proteins, it is difficult to examine effects of propofol on Gq␣ involved in M1 receptor-mediated signal transduction. We previously showed that stable induction of the current with the intracellular injection of GTP␥S requires overexpression of Gq␣, indicating that the heterologously expressed Gq␣ provides a useful system for studying functional roles of Gq␣ (Kaibara et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Site of Action of the General Anesthetic Propofol in Muscarinic M1 Receptor-Mediated Signal Transduction

Murasaki

Kaibara²,

Nagase³

et al. 2003

The Journal of Pharmacology and Experimental Therapeutics

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Although a potential target site of general anesthetics is primarily the GABA A receptor, a chloride ion channel, a previous study suggested that the intravenous general anesthetic propofol attenuates the M1 muscarinic acetylcholine receptor (M1 receptor)-mediated signal transduction. In the present study, we examined the target site of propofol in M1 receptor-mediated signal transduction. Two-electrode voltage-clamp method was used in Xenopus oocytes expressing both M1 receptors and associated G protein ␣ subunits (Gq␣). Propofol inhibited M1 receptor-mediated signal transduction in a dose-dependent manner (IC 50 ϭ 50 nM). Injection of guanosine 5Ј-3-O-(thio)triphosphate (GTP␥S) into oocytes overexpressing Gq␣ was used to investigate direct effects of propofol on G protein coupled with the M1 receptor. Propofol did not affect activation of Gq␣-mediated signal transduction with the intracellular injection of GTP␥S. We also studied effects of propofol on l-[N- Effects of propofol on Gs-and Gi/o-coupled signal transduction were investigated, using oocytes expressing the ␤2 adrenoceptor (␤2 receptor)/cystic fibrosis transmembrane conductance regulator or oocytes expressing the M2 muscarinic acetylcholine receptor (M2 receptor)/Kir3.1 (a member of G protein-gated inwardly rectifying K ϩ channels). Neither ␤2 receptor-mediated nor M2 receptor-mediated signal transduction was inhibited by a relatively high concentration of propofol (50 M). These results indicate that propofol inhibits M1 receptor-mediated signal transduction by selectively disrupting interaction between the receptor and associated G protein.

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Functional Properties of Ca2+‐Dependent Cl− Channels and Bestrophins: Do They Correlate?

Arreola

Pérez‐Cornejo

2006

Advances in Molecular and Cell Biology

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GTPγS-Induced Ca2+ Activated Cl− Currents: Its Stable Induction by Gqα Overexpression in Xenopus Oocytes

Cited by 4 publications

References 8 publications

Expression of the polycystin-1 C-terminal cytoplasmic tail increases Cl- channel activity in Xenopus oocytes

Expression of the polycystin-1 C-terminal cytoplasmic tail increases Cl- channel activity in Xenopus oocytes

Site of Action of the General Anesthetic Propofol in Muscarinic M1 Receptor-Mediated Signal Transduction

Functional Properties of Ca2+‐Dependent Cl− Channels and Bestrophins: Do They Correlate?

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