Cardiovascular Research Advance Access first published online on August 5, 2008
This version [Corrected Proof] published online on August 23, 2008
Cardiovascular Research, doi:10.1093/cvr/cvn209
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Role of src-family kinases in hypoxic vasoconstriction of rat pulmonary artery
Department of Asthma, Allergy and Respiratory Science, School of Medicine, Kings College London, Room 3.20, Franklin Wilkins Building, Stamford Street, London SE1 9NH, UK
* Corresponding author. Tel: +44 20 7848 4297; fax: +44 20 7848 3743. E-mail address: greg.knock{at}kcl.ac.uk
Aims: We investigated the role of src-family kinases (srcFKs) in hypoxic pulmonary vasoconstriction (HPV) and how this relates to Rho-kinase-mediated Ca2+ sensitization and changes in intracellular Ca2+ concentration ([Ca2+]i).
Methods and results: Intra-pulmonary arteries (IPAs) were obtained from male Wistar rats. HPV was induced in myograph-mounted IPAs. Auto-phosphorylation of srcFKs and phosphorylation of the regulatory subunit of myosin phosphatase (MYPT-1) and myosin light-chain (MLC20) in response to hypoxia were determined by western blotting. Translocation of Rho-kinase and effects of siRNA knockdown of src and fyn were examined in cultured pulmonary artery smooth muscle cells (PASMCs). [Ca2+]i was estimated in Fura-PE3-loaded IPA. HPV was inhibited by two blockers of srcFKs, SU6656 and PP2. Hypoxia enhanced phosphorylation of three srcFK proteins at Tyr-416 (60, 59, and 54 kDa, corresponding to src, fyn, and yes, respectively) and enhanced srcFK-dependent tyrosine phosphorylation of multiple target proteins. Hypoxia caused a complex, time-dependent enhancement of MYPT-1 and MLC20 phosphorylation, both in the absence and presence of pre-constriction. The sustained component of this enhancement was blocked by SU6656 and the Rho-kinase inhibitor Y27632. In PASMCs, hypoxia caused translocation of Rho-kinase from the nucleus to the cytoplasm, and this was prevented by anti-src siRNA and to a lesser extent by anti-fyn siRNA. The biphasic increases in [Ca2+]i that accompany HPV were also inhibited by PP2.
Conclusion: Hypoxia activates srcFKs and triggers protein tyrosine phosphorylation in IPA. Hypoxia-mediated Rho-kinase activation, Ca2+ sensitization, and [Ca2+]i responses are depressed by srcFK inhibitors and/or siRNA knockdown, suggesting a central role of srcFKs in HPV.
KEYWORDS Hypoxia; Tyrosine kinase; src-family kinase; Rho-kinase; Pulmonary; Vasoconstriction
Time for primary review: 28 days