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The Tyrosine Kinase Pyk2 Promotes Sustained Contraction of Vascular Smooth Muscle and is Activated Downstream of Calcium Entry
Author(s) -
Mills Ryan,
Mita Mitsuo,
Sutherland Cindy,
Walsh Michael
Publication year - 2015
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.29.1_supplement.804.4
Subject(s) - sodium orthovanadate , contraction (grammar) , autophosphorylation , vascular smooth muscle , ionomycin , myosin light chain kinase , depolarization , muscle contraction , chemistry , rhoa , rho associated protein kinase , electrical impedance myography , myosin light chain phosphatase , medicine , endocrinology , protein tyrosine phosphatase , biophysics , phosphorylation , biology , calcium , signal transduction , biochemistry , protein kinase a , smooth muscle , vasodilation
Objective Sustained contraction of vascular smooth muscle is elicited by Ca 2+ sensitization, which involves activation of the RhoA/Rho‐kinase pathway and inhibition of myosin light‐chain phosphatase (MLCP). We demonstrated previously that the tyrosine kinase Pyk2 becomes activated in rat caudal arterial smooth muscle during sustained contraction induced by membrane depolarization, and that contraction is inhibited by Pyk2 inhibitors. For the current work, we focused on the activation of Pyk2 by upstream signals. Methods: Rat caudal arterial smooth muscle strips were contracted either by 87 mM K + , 5 mM sodium orthovanadate or 10 μM ionomycin in HEPES‐Tyrode's solution. Contractile force was measured by wire myography. Results: Sustained contraction of rat caudal arterial smooth muscle was sensitive to inhibition by Pyk2 inhibitors (IC 50 = 0.49 ± 0.07 µM) which correlated with inhibition of Pyk2 autophosphorylation, while the initial rapid contraction was only inhibited at higher concentrations (IC 50 = 2.4 ± 0.16 μM). The tyrosine phosphatase inhibitor sodium orthovanadate induced contraction and Pyk2 autophosphorylation. Contraction was inhibited by the Pyk2 inhibitor PF‐431396 with an IC 50 of 66 ± 17 nM. Phosphorylation of Pyk2 was also induced by elevation of intracellular Ca 2+ concentration using ionomycin. Conclusions The results support a model whereby Pyk2 becomes activated after the initial period of depolarization‐induced Ca2+ influx, and promotes Ca 2+ sensitization to maintain force during prolonged stimulation. This research was supported by a grant from the Canadian Institutes of Health Research.