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Elucidating new mechanisms in vasoconstrictor signal transduction: inhibition of Kv7.5 channel activity by PKCα
Author(s) -
Hummert Valerie,
Brueggemann Lioubov I,
Byron Kenneth L
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1081.7
Subject(s) - protein kinase c , signal transduction , chemistry , microbiology and biotechnology , neuroscience , biology
Physiological concentrations of arginine 8 ‐vasopressin (AVP) induce vasoconstriction by increasing the influx of calcium (Ca 2+ ) through voltage‐sensitive Ca 2+ channels (VSCC) in vascular smooth muscle cells (VSMCs). We recently reported that AVP activates VSCCs through a protein kinase C (PKC)‐dependent suppression of Kv7.5 potassium channel activity. However, the PKC isoform that mediates these responses has yet to be identified. Here, we tested the hypothesis that PKCα mediates the suppression of Kv7.5 currents using cultured rat aortic (A7r5) or freshly isolated mesenteric artery VSMCs. VSMCs were transduced with a rapamycin‐inducible, GFP‐expressing PKCα adenoviral vector. Kv7.5 currents were measured by patch clamp electrophysiology, and PKCα translocation was measured as an increase in the ratio of peripheral to whole cell fluorescence intensity. Under voltage clamp conditions (−20mV holding potential), Kv7.5 currents were significantly reduced upon rapamycin treatment, as compared to the same cells prior to treatment. The time course of Kv7.5 current inhibition ran parallel to the rapamycin‐induced PKCα translocation. We found that Kv7.5 protein co‐immunoprecipitates with a scaffolding protein, A‐kinase anchoring protein 150 (AKAP150). We propose that PKCα and Kv7.5 interact within an AKAP150‐containing signaling complex, enabling PKCα‐mediated suppression of Kv7.5 currents.