Premium
An essential role of myosin light‐chain kinase in the regulation of agonist‐ and fluid flow‐stimulated Ca 2+ influx in endothelial cells
Author(s) -
Watanabe Hiroshi,
Takahashi Reiko,
Zhang XuXIA,
Goto Yoshinori,
Hayashi Hideharu,
Ando Joji,
Isshiki Masashi,
Seto Minoru,
Hidaka Hiroyoshi,
Niki Ichiro,
Ohno Ryuzo
Publication year - 1998
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.12.3.341
Subject(s) - myosin light chain kinase , thapsigargin , extracellular , chemistry , biophysics , intracellular , microbiology and biotechnology , phosphorylation , cytosol , myosin , biochemistry , biology , enzyme
Cytosolic Ca 2+ ([Ca 2+ ];) plays an important role in endothelial cell signaling. Although it has been suggested that the influx of Ca 2+ can be triggered by depletion of intracellular Ca 2+ stores, the mechanism (or mechanisms) underlying this phenomenon needs further elaboration. In the present study, involvement of myosin light‐chain kinase (MLCK) in the regulation of Ca 2+ signaling was investigated in agonist‐ and fluid flow‐stimulated endothelial cells loaded with Ca 2+ ‐sensitive dyes. Bradykinin (BK) and thapsigargin caused an increase in [Ca 2+ ] i followed by a sustained rise due to Ca 2+ influx from extracellular space and shifted total myosin light‐chain (MLC) from the unphosphorylated to the diphosphorylated form. ML‐9 (100 pM), an inhibitor of MLCK, abolished Ca 2+ influx and prevented MLC diphosphorylation in BK‐ and thapsigargin‐treated cells, but did not affect Ca 2+ mobilization from internal stores. Fluid flow stimulation (shear stress=5 dynes/cm 2 ) increased [Ca 2+ ] i and enhanced MLC phosphorylation. ML‐9 also inhibited Ca 2+ response and MLC phosphorylation in fluid flow‐stimulated cells. The Ca 2+ influx in response to BK was linearly correlated with the diphosphorylation of MLC in ML‐9 treated cells. Effects of ML‐5 and ML‐7, analogs of ML‐9, to inhibit Ca 2+ influx paralleled their potencies to inhibit MLCK activity. These findings demonstrate that MLCK plays an essential role in regulating the plasmalemmal Ca 2+ influx in agonist‐ and fluid flow‐stimulated endothelial cells. This study is the first to report the close relationship between Ca 2+ influx and MLC diphosphorylation.—Watanabe, H., Takahashi, R., Zhang, X.‐X., Goto, Y., Hayashi, H., Ando, J., Isshiki, M., Seto, M., Hidaka, H., Niki, I., Ohno, R. An essential role of myosin light‐chain kinase in the regulation of agonist‐ and fluid flow‐stimulated Ca 2+ influx in endothelial cells. FASEB J. 12, 341–348 (1998)