Heterocomplex Formation between MBL/Ficolin/CL-11–Associated Serine Protease-1 and -3 and MBL/Ficolin/CL-11–Associated Protein-1
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Heterocomplex Formation between MBL/Ficolin/CL-11–Associated Serine Protease-1 and -3 and MBL/Ficolin/CL-11–Associated Protein-1. / Rosbjerg, Anne; Munthe-Fog, Lea; Garred, Peter; Skjoedt, Mikkel-Ole.
In: Journal of immunology (Baltimore, Md. : 1950), Vol. 192, No. 9, 2014, p. 4352-60.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Heterocomplex Formation between MBL/Ficolin/CL-11–Associated Serine Protease-1 and -3 and MBL/Ficolin/CL-11–Associated Protein-1
AU - Rosbjerg, Anne
AU - Munthe-Fog, Lea
AU - Garred, Peter
AU - Skjoedt, Mikkel-Ole
PY - 2014
Y1 - 2014
N2 - The activity of the complement system is tightly controlled by many fluid-phase and tissue-bound regulators. Mannose-binding lectin (MBL)/ficolin/collectin-11-associated protein-1 (MAP-1) is a recently discovered plasma protein that acts as an upstream inhibitor of the lectin complement pathway (LCP). It has previously been shown that MAP-1 can compete with the MBL/ficolin/collectin-11-associated serine proteases (MASPs) in binding to MBL and the ficolins. However, this mechanism may only partly explain the inhibitory complement effect of MAP-1. We hypothesized that MAP-1 is also involved in heterocomplex formation with the MASPs thereby breaking the stoichiometry of the activation complexes of the LCP, which could represent an alternative mechanism of MAP-1-mediated complement inhibition. We assessed the heterocomplex formation with ELISA, size-exclusion chromatography, and immunoblotting using both recombinant proteins and serum/plasma. We found that rMAP-1 can engage in heterocomplexes with rMASP-1 and rMASP-3 in a calcium-dependent manner. Moreover, we discovered that rMASP-1 and rMASP-3 also form heterocomplexes under these conditions. Complexes containing both MAP-1 and MASP-1 or -3 were detected in normal human serum and plasma, and depletion of the LCP recognition molecules from ficolin-3-deficient human serum showed that free circulating heterocomplexes also exist in the blood, although the major part appears to be associated with the LCP recognition molecules. Altogether, these findings suggest that MASPs can associate in various combinations and bring new perspectives to the complexity of lectin pathway-driven complement activation.
AB - The activity of the complement system is tightly controlled by many fluid-phase and tissue-bound regulators. Mannose-binding lectin (MBL)/ficolin/collectin-11-associated protein-1 (MAP-1) is a recently discovered plasma protein that acts as an upstream inhibitor of the lectin complement pathway (LCP). It has previously been shown that MAP-1 can compete with the MBL/ficolin/collectin-11-associated serine proteases (MASPs) in binding to MBL and the ficolins. However, this mechanism may only partly explain the inhibitory complement effect of MAP-1. We hypothesized that MAP-1 is also involved in heterocomplex formation with the MASPs thereby breaking the stoichiometry of the activation complexes of the LCP, which could represent an alternative mechanism of MAP-1-mediated complement inhibition. We assessed the heterocomplex formation with ELISA, size-exclusion chromatography, and immunoblotting using both recombinant proteins and serum/plasma. We found that rMAP-1 can engage in heterocomplexes with rMASP-1 and rMASP-3 in a calcium-dependent manner. Moreover, we discovered that rMASP-1 and rMASP-3 also form heterocomplexes under these conditions. Complexes containing both MAP-1 and MASP-1 or -3 were detected in normal human serum and plasma, and depletion of the LCP recognition molecules from ficolin-3-deficient human serum showed that free circulating heterocomplexes also exist in the blood, although the major part appears to be associated with the LCP recognition molecules. Altogether, these findings suggest that MASPs can associate in various combinations and bring new perspectives to the complexity of lectin pathway-driven complement activation.
KW - Animals
KW - Blotting, Western
KW - CHO Cells
KW - Coculture Techniques
KW - Complement Activation
KW - Complement Pathway, Mannose-Binding Lectin
KW - Cricetinae
KW - Cricetulus
KW - Enzyme-Linked Immunosorbent Assay
KW - Humans
KW - Lectins
KW - Mannose-Binding Lectins
KW - Mannose-Binding Protein-Associated Serine Proteases
KW - Recombinant Proteins
KW - Transfection
U2 - 10.4049/jimmunol.1303263
DO - 10.4049/jimmunol.1303263
M3 - Journal article
C2 - 24683193
VL - 192
SP - 4352
EP - 4360
JO - Journal of Immunology
JF - Journal of Immunology
SN - 0022-1767
IS - 9
ER -
ID: 138617612