Receptor-dependent activation of store-operated calcium entry increases endothelial cell permeability.
The present study evaluated the necessity of store-operated Ca(2+) entry in mediating thrombin-induced 20-kDa myosin light chain (MLC(20)) phosphorylation and increased permeability in bovine pulmonary artery endothelial cells (BPAECs). Thrombin (7 U/ml) and thapsigargin (1 microM) activated Ca(2+) entry through a common pathway in confluent BPAECs. Similar increases in MLC(20) phosphorylation were observed 5 min after thrombin and thapsigargin challenge, although thrombin produced a sustained increase in MLC(20) phosphorylation that was not observed in response to thapsigargin. Neither agonist increased MLC(20) phosphorylation when Ca(2+) influx was inhibited. Thrombin and thapsigargin induced inter-endothelial cell gap formation and increased FITC-dextran (molecular radii 23 A) transfer across confluent BPAEC monolayers. Activation of store-operated Ca(2+) entry was required for thapsigargin and thrombin receptor-activating peptide to increase permeability, demonstrating that activation of store-operated Ca(2+) entry is coupled with MLC(20) phosphorylation and is associated with intercellular gap formation and increased barrier transport of macromolecules. Unlike thrombin receptor-activating peptide, thrombin increased permeability without activation of store-operated Ca(2+) entry, suggesting that it partly disrupts the endothelial barrier through a proteolytic mechanism independent of Ca(2+) signaling.
Moore
T M
TM
Department of Pharmacology, University of South Alabama College of Medicine, Mobile, Alabama 36688, USA.
Norwood
N R
NR
Creighton
J R
JR
Babal
P
P
Brough
G H
GH
Shasby
D M
DM
Stevens
T
T
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002463:Cell Membrane Permeability / Q000502:physiology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology; D007700:Kinetics; D018994:Myosin Light Chains / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D010766:Phosphorylation; D011651:Pulmonary Artery; D019284:Thapsigargin / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology
D018994:Myosin Light Chains; D019284:Thapsigargin; D009219:Myosin-Light-Chain Kinase; D013917:Thrombin; D002118:Calcium