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Endothelin‐1 Blocks BK Channels by Stimulating Protein Kinase C‐Mediated Rab11A Phosphorylation at Serine 177 in Arterial Smooth Muscle Cells
Author(s) -
Zhai Xue,
Leo M. Dennis,
Jaggar Jonathan H.
Publication year - 2016
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.30.1_supplement.1281.3
Subject(s) - bk channel , protein kinase c , microbiology and biotechnology , myocyte , chemistry , staurosporine , patch clamp , phosphorylation , biology , membrane potential , biochemistry , receptor
Large‐conductance calcium (Ca 2+ )‐activated potassium channels (BK) composed of BKα and auxiliary β1 subunits control arterial myocyte contractility. BKα subunits are primarily plasma membrane‐localized, whereas β1 subunits are stored within intracellular Rab11A‐positive recycling endosomes in arterial myocytes. Nitric oxide (NO) stimulates rapid surface trafficking of auxiliary β1 subunits, which stimulates BK channels, leading to vasodilation. Vasoconstrictors, including endothelin‐1 (ET‐1), inhibit BK channels but mechanisms involved are unclear. Here, using surface biotinylation and immunoFRET microscopy, we found that ET‐1 attenuated NO‐induced surface trafficking of β1 subunits in cerebral artery myocytes. Bisindolylmaleimide‐1 (BIM‐1), a protein kinase C (PKC) inhibitor, blocked this inhibitory effect of ET‐1. Bioinformatic analysis found five potential PKC phosphorylation sites on Rab11A, of which Ser177 had the highest probability. Arterial transfection with a S177A Rab11A mutant blocked ET‐1‐inhibition of β1 surface trafficking. Patch‐clamp experiments indicated that ET‐1‐inhibition of β1 trafficking reduced the ability of NO to increase BK channel open probability (Po). The S177A Rab11A mutant attenuated ET‐1 inhibition of both single BK channel Po and Ca 2+ spark‐induced transient BK currents. In summary, our data indicate that ET‐1 stimulates PKC‐mediated phosphorylation of Rab11A at serine 177, which blocks surface trafficking of β1 subunits, leading to BK channel inhibition in arterial myocytes. Support or Funding Information NIH/NHLBI grants HL67061 and HL110347