title: Role of myosin light chain kinase in cardiotrophin-1-induced cardiac myofibroblast cell migration.
abstract: Chemotactic movement of myofibroblasts is recognized as a common means for their sequestration to the site of tissue injury. Following myocardial infarction (MI), recruitment of cardiac myofibroblasts to the infarct scar is a critical step in wound healing. Contractile myofibroblasts express embryonic smooth muscle myosin, α-smooth muscle actin, as well as collagens I and III. We examined the effects of cardiotrophin-1 (CT-1) in the induction of primary rat ventricular myofibroblast motility. Changes in membrane potential (E(m)) and Ca(2+) entry were studied to reveal the mechanisms for induction of myofibroblast migration. CT-1-induced cardiac myofibroblast cell migration, which was attenuated through the inhibition of JAK2 (25 μM AG490), and myosin light chain kinase (20 μM ML-7). Inhibition of K(+) channels (1 mM tetraethylammonium or 100 μM 4-aminopyridine) and nonselective cation channels by 10 μM gadolinium (Gd(3+)) significantly reduced migration in the presence of CT-1. CT-1 treatment caused a significant increase in myosin light chain phosphorylation, which could be inhibited by incubation in Ca(2+)-free conditions or by application of AG490, ML-7, and W7 (100 μM; calmodulin inhibitor). Monitoring myofibroblast membrane potential with potentiometric fluorescent DiBAC(4)(3) dye revealed a biphasic response to CT-1 consisting of an initial depolarization followed by hyperpolarization. Increased intracellular Ca(2+), as assessed by fluo 3, occurred immediately after membrane depolarization and attenuated at the time of maximal hyperpolarization. CT-1 exerts chemotactic effects via multiple parallel signaling modalities in ventricular myofibroblasts, including changes in membrane potential, alterations in intracellular calcium, and activation of a number of intracellular signaling pathways. Further study is warranted to determine the precise role of K(+) currents in this process.
authors.affiliation: Department of Physiology, Faculty of Medicine, Institute of Cardiovascular Sciences, University of Manitoba, Winnipeg, Canada.
authors.forename: Darren H
authors.initials: DH
authors.lastname: Freed
authors.forename: Lisa
authors.initials: L
authors.lastname: Chilton
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
authors.forename: Aran L
authors.initials: AL
authors.lastname: Dangerfield
authors.forename: Joshua E
authors.initials: JE
authors.lastname: Raizman
authors.forename: Sunil G
authors.initials: SG
authors.lastname: Rattan
authors.forename: Neeraj
authors.initials: N
authors.lastname: Visen
authors.forename: Larry V
authors.initials: LV
authors.lastname: Hryshko
authors.forename: Ian M C
authors.initials: IM
authors.lastname: Dixon
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism; D024722:Cardiac Myosins / Q000378:metabolism; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism*; D005682:Gadolinium / Q000378:metabolism; D006352:Heart Ventricles / Q000166:cytology / Q000201:enzymology; D006801:Humans; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials; D058628:Myofibroblasts / Q000187:drug effects / Q000201:enzymology*; D018994:Myosin Light Chains / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D002147:Calmodulin; D016207:Cytokines; D018994:Myosin Light Chains; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D047428:Protein Kinase Inhibitors; D011994:Recombinant Proteins; C107184:myosin light chain 2; C092073:cardiotrophin 1; D005682:Gadolinium; C507927:Jak2 protein, rat; D053614:Janus Kinase 2; D009219:Myosin-Light-Chain Kinase; D024722:Cardiac Myosins; D011188:Potassium; D002118:Calcium