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Molecular mechanism in protein kinase C‐induced inhibition of recombinant vascular KATP channels
Author(s) -
Jiao Jundong,
Garg vivek,
Yang Baofeng,
Hu Keli
Publication year - 2008
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.22.1_supplement.1201.6
Subject(s) - dynamin , caveolae , protein kinase c , microbiology and biotechnology , internalization , endocytosis , chemistry , intracellular , vascular smooth muscle , protein kinase a , signal transduction , biology , biochemistry , endocrinology , kinase , cell , smooth muscle
It is known that activation of protein kinase C (PKC) inhibits KATP channels in vascular smooth muscles. This signal transduction pathway has been implicated in the regulation of blood flow by endogenous vasoactive transmitters. However, the mechanism by which PKC down‐regulates KATP channels remains elusive. To test the hypothesis that caveolae‐dependent internalization of KATP channels is involved in PKC‐mediated inhibition of the channel, we employed HEK293 cells transfected with Kir6.1/SUR2B, a potential cloned equivalent of vascular smooth muscles. Phorbol 12‐myristate 13‐acetate (PMA, 1 μM) treatment at 37°C for 15 minutes caused substantial redistribution of KATP channels from cell membrane to intracellular vesicles, whereas distrupting caveolae by depletion of cholesterol with methyl‐betacyclodextrin significantly abolished the actions of PMA. Whole‐cell voltage clamp experiments revealed that a dominant negative mutant of dynamin (K44E) significantly reduced PMA‐induced inhibition of KATP currents in comparison with wild‐type dynamin (26.5±2.9% vs 49.9±4.8%, p<0.01, n=5). Consistently, immunofluorescence microscopy further demonstrated that dynamin K44E largely prevented the internalization of KATP channels induced by PMA. We concluded that activation of PKC by PMA inhibits recombinant vascular KATP channels via a dynamin‐dependent, caveolar‐related mechanism.