Role of protein kinase Czeta in thrombin-induced endothelial permeability changes: inhibition by angiopoietin-1.
Endothelial cell leakiness is regulated by mediators such as thrombin, which promotes endothelial permeability, and anti-inflammatory agents, such as angiopoietin-1. Here we define a new pathway involved in thrombin-induced permeability that involves the atypical protein kinase C isoform, PKCzeta. Chemical inhibitor studies implicated the involvement of an atypical PKC isoform in thrombin-induced permeability changes in human umbilical vein endothelial cells. Thrombin stimulation resulted in PKCzeta, but not the other atypical PKC isoform, PKClambda, translocating to the membrane, an event known to be critical to enzyme activation. The involvement of PKCzeta was confirmed by overexpression of constitutively active PKCzeta, resulting in enhanced basal permeability. Dominant-negative PKCzeta prevented the thrombin-mediated effects on endothelial cell permeability and inhibited thrombin-induced activation of PKCzeta. Rho activation does not appear to play a role, either upstream or downstream of PKCzeta, as C3 transferase does not block thrombin-induced PKCzeta activation and dominant-negative PKCzeta does not block thrombin-induced Rho activation. Finally, we show that angiopoietin-1 inhibits thrombin-induced PKCzeta activation, Rho activation, and Ca(++) flux, thus demonstrating that the powerful antipermeability action of angiopoietin-1 is mediated by its action on a number of signaling pathways induced by thrombin and implicated in permeability changes.
Li
Xiaochun
X
Vascular Biology Laboratory, Division of Human Immunology, Hanson Institute, Institute of Medical and Veterinary Science, Frome Road, Adelaide, South Australia 5000.
Hahn
Christopher N
CN
Parsons
Michelle
M
Drew
Jenny
J
Vadas
Mathew A
MA
Gamble
Jennifer R
JR
D000199:Actins / Q000378:metabolism; D042683:Angiopoietin-1 / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D010539:Permeability / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014470:Umbilical Cord / Q000166:cytology; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D000099221:Protein Kinase C zeta
D000199:Actins; D042683:Angiopoietin-1; D002118:Calcium; D004791:Enzyme Inhibitors; D011493:Protein Kinase C; D013917:Thrombin; D020741:rho GTP-Binding Proteins; D000099221:Protein Kinase C zeta