Role of MBL-associated serine protease (MASP) on activation of the lectin complement pathway.
Mannose-binding lectin (MBL) and ficolin are pattern recognition molecules in the complex with the MBL-associated serine proteases (MASPs). Three kinds of MASPs, termed as MASP-1, MASP-2 and MASP-3 have been identified. When MBL or ficolins binds to carbohydrates on the surface of microbes, conformational modifications of these molecules trigger to activate zymogens of MASPs, followed by consequential complement activation. MASP-2 cleaves C4 and C2 to make a C3 convertase, C4b2a. MASP-1 has an ability to cleave C3 directly, although this activity has not been detected in physiological conditions. Natural target molecules for MASP-3 are still discussible. To elucidate the physiological meanings of MASPs, we generated MASPs-deficient mice. Not only MASP-2-deficient mouse but also MASP-1-/MASP-3-deficient mouse reduced activities for C3 deposition on the surface of mannan and zymosan, suggesting MASP-1/3 also contribute the activation of complement by the lectin pathway. Also, MASP-1/3-deficient mice showed the susceptible to an influenza virus.
Takahashi
Minoru
M
Department of Immunology, Fukushima Medical University School of Medicine, Japan. minolta@fmu.ac.jp
Mori
Shuichi
S
Shigeta
Shiro
S
Fujita
Teizo
T
D000818:Animals; D003167:Complement Activation; D003171:Complement Pathway, Classical / Q000276:immunology*; D019143:Evolution, Molecular; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D007527:Isoenzymes / Q000235:genetics / Q000276:immunology*; D037102:Lectins / Q000276:immunology* / Q000378:metabolism; D037241:Mannose-Binding Lectins / Q000378:metabolism; D050606:Mannose-Binding Protein-Associated Serine Proteases / Q000235:genetics / Q000276:immunology*; D000097604:Ficolins
D007527:Isoenzymes; D037102:Lectins; D037241:Mannose-Binding Lectins; D050606:Mannose-Binding Protein-Associated Serine Proteases; D000097604:Ficolins