MAp19, the alternative splice product of the MASP2 gene

Søren Egedal Degn; Steffen Thiel; Ole Nielsen; Annette G Hansen; Rudi Steffensen; Jens C Jensenius

doi:10.1016/j.jim.2011.08.006

MAp19, the alternative splice product of the MASP2 gene

Søren Egedal Degn, Steffen Thiel, Ole Nielsen, Annette G Hansen, Rudi Steffensen, Jens C Jensenius

Department of Biomedicine - Medical Microbiology and Immunology

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

61 Citations (Scopus)

Abstract

The lectin pathway of complement is a central part of innate immunity, but as a powerful inducer of inflammation it needs to be tightly controlled. The MASP2 gene encodes two proteins, MASP-2 and MAp19. MASP-2 is the serine protease responsible for lectin pathway activation. The smaller alternative splice product, MAp19, lacks a catalytic domain but retains two of three domains involved in association with the pattern-recognition molecules (PRMs): mannan-binding lectin (MBL), H-ficolin, L-ficolin and M-ficolin. MAp19 reportedly acts as a competitive inhibitor of MASP-2-mediated complement activation. In light of a ten times lower affinity of MAp19, versus MASP-2, for association with the PRMs, much higher serum concentrations of MAp19 than MASP-2 would be required for MAp19 to exert such an inhibitory activity. Just four amino acid residues distinguish MAp19 from MASP-2, and these are conserved between man, mouse and rat. Nonetheless we generated monoclonal rat anti-MAp19 antibodies and established a quantitative assay. We found the concentration of MAp19 in serum to be 217 ng/ml, i.e., 11nM, comparable to the 7 nM of MASP-2. In serum all MASP-2, but only a minor fraction of MAp19, was associated with PRMs. In contrast to previous reports we found that MAp19 could not compete with MASP-2 for binding to MBL, nor could it inhibit MASP-2-mediated complement activation. Immunohistochemical analyses combined with qRT-PCR revealed that both MAp19 and MASP-2 were mainly expressed in hepatocytes. High levels of MAp19 were found in urine, where MASP-2 was absent.

Original language	English
Journal	Journal of Immunological Methods
Volume	373
Issue	1-2
Pages (from-to)	89-101
Number of pages	13
ISSN	0022-1759
DOIs	https://doi.org/10.1016/j.jim.2011.08.006
Publication status	Published - 2011

Keywords

Alternative Splicing
Animals
Antibodies, Monoclonal
Antibody Affinity
Blotting, Western
Cytoplasm
Gene Expression Profiling
HEK293 Cells
Hepatocytes
Humans
Hybridomas
Immunohistochemistry
Kidney
Lectins
Macrophages, Alveolar
Mannose-Binding Lectin
Mannose-Binding Protein-Associated Serine Proteases
Mice
Protein Binding
Protein Isoforms
Rats
Reverse Transcriptase Polymerase Chain Reaction

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10.1016/j.jim.2011.08.006

A quantitative assay for MAp19, the alternative splice product of the MASP-2 gene
Degn, S. E. (Invited speaker)
6 Sept 2009
Activity: Presentations, memberships, employment, ownership and other activities › Lecture and oral contribution

Cite this

@article{24b21042a58542e482606ccd06ee2f58,

title = "MAp19, the alternative splice product of the MASP2 gene",

abstract = "The lectin pathway of complement is a central part of innate immunity, but as a powerful inducer of inflammation it needs to be tightly controlled. The MASP2 gene encodes two proteins, MASP-2 and MAp19. MASP-2 is the serine protease responsible for lectin pathway activation. The smaller alternative splice product, MAp19, lacks a catalytic domain but retains two of three domains involved in association with the pattern-recognition molecules (PRMs): mannan-binding lectin (MBL), H-ficolin, L-ficolin and M-ficolin. MAp19 reportedly acts as a competitive inhibitor of MASP-2-mediated complement activation. In light of a ten times lower affinity of MAp19, versus MASP-2, for association with the PRMs, much higher serum concentrations of MAp19 than MASP-2 would be required for MAp19 to exert such an inhibitory activity. Just four amino acid residues distinguish MAp19 from MASP-2, and these are conserved between man, mouse and rat. Nonetheless we generated monoclonal rat anti-MAp19 antibodies and established a quantitative assay. We found the concentration of MAp19 in serum to be 217 ng/ml, i.e., 11nM, comparable to the 7 nM of MASP-2. In serum all MASP-2, but only a minor fraction of MAp19, was associated with PRMs. In contrast to previous reports we found that MAp19 could not compete with MASP-2 for binding to MBL, nor could it inhibit MASP-2-mediated complement activation. Immunohistochemical analyses combined with qRT-PCR revealed that both MAp19 and MASP-2 were mainly expressed in hepatocytes. High levels of MAp19 were found in urine, where MASP-2 was absent.",

keywords = "Alternative Splicing, Animals, Antibodies, Monoclonal, Antibody Affinity, Blotting, Western, Cytoplasm, Gene Expression Profiling, HEK293 Cells, Hepatocytes, Humans, Hybridomas, Immunohistochemistry, Kidney, Lectins, Macrophages, Alveolar, Mannose-Binding Lectin, Mannose-Binding Protein-Associated Serine Proteases, Mice, Protein Binding, Protein Isoforms, Rats, Reverse Transcriptase Polymerase Chain Reaction",

author = "Degn, {S{\o}ren Egedal} and Steffen Thiel and Ole Nielsen and Hansen, {Annette G} and Rudi Steffensen and Jensenius, {Jens C}",

year = "2011",

doi = "10.1016/j.jim.2011.08.006",

language = "English",

volume = "373",

pages = "89--101",

journal = "Journal of Immunological Methods",

issn = "0022-1759",

publisher = "Elsevier B.V.",

number = "1-2",

}

TY - JOUR

T1 - MAp19, the alternative splice product of the MASP2 gene

AU - Degn, Søren Egedal

AU - Thiel, Steffen

AU - Nielsen, Ole

AU - Hansen, Annette G

AU - Steffensen, Rudi

AU - Jensenius, Jens C

PY - 2011

Y1 - 2011

N2 - The lectin pathway of complement is a central part of innate immunity, but as a powerful inducer of inflammation it needs to be tightly controlled. The MASP2 gene encodes two proteins, MASP-2 and MAp19. MASP-2 is the serine protease responsible for lectin pathway activation. The smaller alternative splice product, MAp19, lacks a catalytic domain but retains two of three domains involved in association with the pattern-recognition molecules (PRMs): mannan-binding lectin (MBL), H-ficolin, L-ficolin and M-ficolin. MAp19 reportedly acts as a competitive inhibitor of MASP-2-mediated complement activation. In light of a ten times lower affinity of MAp19, versus MASP-2, for association with the PRMs, much higher serum concentrations of MAp19 than MASP-2 would be required for MAp19 to exert such an inhibitory activity. Just four amino acid residues distinguish MAp19 from MASP-2, and these are conserved between man, mouse and rat. Nonetheless we generated monoclonal rat anti-MAp19 antibodies and established a quantitative assay. We found the concentration of MAp19 in serum to be 217 ng/ml, i.e., 11nM, comparable to the 7 nM of MASP-2. In serum all MASP-2, but only a minor fraction of MAp19, was associated with PRMs. In contrast to previous reports we found that MAp19 could not compete with MASP-2 for binding to MBL, nor could it inhibit MASP-2-mediated complement activation. Immunohistochemical analyses combined with qRT-PCR revealed that both MAp19 and MASP-2 were mainly expressed in hepatocytes. High levels of MAp19 were found in urine, where MASP-2 was absent.

AB - The lectin pathway of complement is a central part of innate immunity, but as a powerful inducer of inflammation it needs to be tightly controlled. The MASP2 gene encodes two proteins, MASP-2 and MAp19. MASP-2 is the serine protease responsible for lectin pathway activation. The smaller alternative splice product, MAp19, lacks a catalytic domain but retains two of three domains involved in association with the pattern-recognition molecules (PRMs): mannan-binding lectin (MBL), H-ficolin, L-ficolin and M-ficolin. MAp19 reportedly acts as a competitive inhibitor of MASP-2-mediated complement activation. In light of a ten times lower affinity of MAp19, versus MASP-2, for association with the PRMs, much higher serum concentrations of MAp19 than MASP-2 would be required for MAp19 to exert such an inhibitory activity. Just four amino acid residues distinguish MAp19 from MASP-2, and these are conserved between man, mouse and rat. Nonetheless we generated monoclonal rat anti-MAp19 antibodies and established a quantitative assay. We found the concentration of MAp19 in serum to be 217 ng/ml, i.e., 11nM, comparable to the 7 nM of MASP-2. In serum all MASP-2, but only a minor fraction of MAp19, was associated with PRMs. In contrast to previous reports we found that MAp19 could not compete with MASP-2 for binding to MBL, nor could it inhibit MASP-2-mediated complement activation. Immunohistochemical analyses combined with qRT-PCR revealed that both MAp19 and MASP-2 were mainly expressed in hepatocytes. High levels of MAp19 were found in urine, where MASP-2 was absent.

KW - Alternative Splicing

KW - Animals

KW - Antibodies, Monoclonal

KW - Antibody Affinity

KW - Blotting, Western

KW - Cytoplasm

KW - Gene Expression Profiling

KW - HEK293 Cells

KW - Hepatocytes

KW - Humans

KW - Hybridomas

KW - Immunohistochemistry

KW - Kidney

KW - Lectins

KW - Macrophages, Alveolar

KW - Mannose-Binding Lectin

KW - Mannose-Binding Protein-Associated Serine Proteases

KW - Mice

KW - Protein Binding

KW - Protein Isoforms

KW - Rats

KW - Reverse Transcriptase Polymerase Chain Reaction

U2 - 10.1016/j.jim.2011.08.006

DO - 10.1016/j.jim.2011.08.006

M3 - Journal article

C2 - 21871896

SN - 0022-1759

VL - 373

SP - 89

EP - 101

JO - Journal of Immunological Methods

JF - Journal of Immunological Methods

IS - 1-2

ER -

MAp19, the alternative splice product of the MASP2 gene

Abstract

Keywords

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A quantitative assay for MAp19, the alternative splice product of the MASP-2 gene

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