Complement protease MASP-1 activates human endothelial cells: PAR4 activation is a link between complement and endothelial function.
Activation of the complement system can induce and enhance inflammatory reaction. Mannose-binding lectin-associated serine protease-1 (MASP-1) is an abundant protease of the complement lectin pathway; however, its physiological function is unclear. In this study, we demonstrate for the first time that MASP-1 is able to activate Ca(2+) signaling, NF-kappaB, and p38 MAPK pathways in cultured HUVECs. Activation was initiated by MASP-1 only; the related protease, MASP-2, had no such effect. The phenomenon was dependent on the proteolytic activity of MASP-1, suggesting modulation of endothelial cell function through a protease-activated receptor (PAR). Using synthetic peptide substrates representing the protease-sensitive regions of PARs, we were able to demonstrate that PAR4 is a target of MASP-1. The presence of functionally active PAR4 in HUVECs was demonstrated using PAR4 agonist peptide and mRNA quantification. Finally, we showed that the amount of membrane-bound intact PAR4 decreases after MASP-1 treatment. All of these results provide a novel link between the regulation of endothelial cell function and complement system activation, and they suggest that MASP-1-induced PAR4 activation could contribute to the development of the inflammatory reaction.
Megyeri
Márton
M
Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest, Hungary.
Makó
Veronika
V
Beinrohr
László
L
Doleschall
Zoltán
Z
Prohászka
Zoltán
Z
Cervenak
László
L
Závodszky
Péter
P
Gál
Péter
P
D020013:Calcium Signaling / Q000276:immunology; D002460:Cell Line; D003165:Complement System Proteins / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology* / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D004789:Enzyme Activation / Q000276:immunology; D006801:Humans; D006868:Hydrolysis; D018836:Inflammation Mediators / Q000378:metabolism / Q000494:pharmacology; D007424:Intracellular Fluid / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000276:immunology; D050606:Mannose-Binding Protein-Associated Serine Proteases / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D018179:Receptors, Thrombin / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology
D018836:Inflammation Mediators; D008565:Membrane Proteins; D016328:NF-kappa B; D018179:Receptors, Thrombin; D003165:Complement System Proteins; D048051:p38 Mitogen-Activated Protein Kinases; C084067:MASP1 protein, human; D050606:Mannose-Binding Protein-Associated Serine Proteases; C112908:protease-activated receptor 4