Penetratin Peptide Potentiates Endogenous Calcium-Activated Chloride Currents in Xenopus oocytes

Penetratin Peptide Potentiates Endogenous Calcium-Activated Chloride Currents in Xenopus oocytes Calcium-activated chloride currents (CaCCs) are required for epithelial electrolyte and fluid secretion, fertilization, sensory transduction and excitability of neurons and smooth muscle. Defolliculated Xenopus oocytes express a robust CaCC formed by a heterologous group of proteins including transmembrane protein 16A (TMEM16A) and bestrophins. Penetratin, a 17-amino acid peptide, potentiated endogenous oocyte CaCCs by ~50-fold at 10 μM, recorded using a two-electrode voltage clamp. CaCC potentiation was rapid and dose-dependent (EC50 = 3.2 μM). Penetratin-potentiated currents reversed at −18 mV and were dependent on the extracellular divalent cations present, showing positive regulation by Ca2+ and Mg2+ but effective block by Zn2+ (IC50 = 5.9 μM). Extracellular Cd2+, Cu2+ and Ba2+ resulted in bimodal responses: CaCC inhibition at low but potentiation at high concentrations. Intracellular BAPTA injection, which prevents activation of CaCCs, and the Cl− channel blockers niflumic acid and DIDS significantly reduced potentiation. In contrast, the K+ channel blockers Cs+, TEA, tertiapin-Q and halothane had no significant effect. This pharmacological profile is consistent with penetratin potentiation of zinc-sensitive CaCCs that are activated by influx of extracellular Ca2+. These findings may stimulate basic research on CaCCs in native cells and may lead to development of novel therapeutics targeting disorders caused by insufficient chloride secretion. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Penetratin Peptide Potentiates Endogenous Calcium-Activated Chloride Currents in Xenopus oocytes

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Publisher
Springer-Verlag
Copyright
Copyright © 2011 by Springer Science+Business Media, LLC
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-011-9359-5
Publisher site
See Article on Publisher Site

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