Serum MASP-1 in complex with MBL activates endothelial cells.
The complement system plays an important role in the induction of inflammation. In this study we demonstrate that the initiation complexes of the lectin pathway, consisting of mannose-binding lectin (MBL) and associated serine proteases (MASPs) elicit Ca(2+) signaling in cultured endothelial cells (HUVECs). This is in agreement with our previous results showing that the recombinant catalytic fragment of MASP-1 activates endothelial cells by cleaving protease activated receptor 4. Two other proteases, MASP-2 and MASP-3 are also associated with MBL. Earlier we showed that recombinant catalytic fragment of MASP-2 cannot activate HUVECs, and in this study we demonstrate that the same fragment of MASP-3 has also no effect. We find the same to be the case if we use recombinant forms of the N-terminal parts of MASP-1 and MASP-2 which only contain non-enzymatic domains. Moreover, stable zymogen mutant form of MASP-1 was also ineffective to stimulate endothelial cells, which suggests that in vivo MASP-1 have the ability to activate endothelial cells directly as well as to activate the lectin pathway simultaneously. We show that among the components of the MBL-MASPs complexes only MASP-1 is able to trigger response in HUVECs and the proteolytic activity of MASP-1 is essential. Our results strengthen the view that MASP-1 plays a central role in the early innate immune response.
Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Karolina út 29, H-1113 Budapest, Hungary.
Márton
M
Megyeri
3rd Department of Medicine, Research Lab, Semmelweis University, Kútvölgyi út 4, H-1125 Budapest, Hungary.
Péter K
PK
Jani
3rd Department of Medicine, Research Lab, Semmelweis University, Kútvölgyi út 4, H-1125 Budapest, Hungary.
Erika
E
Kajdácsi
Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Karolina út 29, H-1113 Budapest, Hungary.
József
J
Dobó
3rd Department of Medicine, Research Lab, Semmelweis University, Kútvölgyi út 4, H-1125 Budapest, Hungary.
Endre
E
Schwaner
Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Karolina út 29, H-1113 Budapest, Hungary.
Balázs
B
Major
1st Department of Obstetrics and Gynecology, Semmelweis University, Baross u. 27, H-1088 Budapest, Hungary.
János
J
Rigó
Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Karolina út 29, H-1113 Budapest, Hungary.
Péter
P
Závodszky
Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark.
Steffen
S
Thiel
3rd Department of Medicine, Research Lab, Semmelweis University, Kútvölgyi út 4, H-1125 Budapest, Hungary.
László
L
Cervenak
Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Karolina út 29, H-1113 Budapest, Hungary. Electronic address: gal.peter@ttk.mta.hu.
Péter
P
Gál
D015153:Blotting, Western; D002118:Calcium / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D003167:Complement Activation / Q000235:genetics / Q000276:immunology; D037582:Complement Pathway, Mannose-Binding Lectin / Q000235:genetics / Q000276:immunology*; D061307:Human Umbilical Vein Endothelial Cells / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics / Q000276:immunology; D037601:Mannose-Binding Lectin / Q000097:blood / Q000276:immunology* / Q000378:metabolism; D050606:Mannose-Binding Protein-Associated Serine Proteases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009154:Mutation; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D059748:Proteolysis; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism
D037601:Mannose-Binding Lectin; D010446:Peptide Fragments; D011994:Recombinant Proteins; C084067:MASP1 protein, human; D050606:Mannose-Binding Protein-Associated Serine Proteases; D002118:Calcium
Cell activation; Complement lectin pathway; Endothelial cell; MBL-associated serine proteases; Protease activated receptor