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PRELP protein inhibits the formation of the complement membrane attack complex
Kaisa E Happonen1, Camilla Melin Fürst, Tore Saxne
1Department of Laboratory Medicine, Division of Medical Protein Chemistry, Wallenberg Laboratory, Skåne University Hospital, Lund University, S-20502 Lund, Sweden.
The Journal of Biological Chemistry
|January 24, 2012
Summary
Proteoglycan PRELP inhibits complement activation by preventing membrane attack complex formation and C3-convertase assembly. This finding suggests PRELP may limit complement-driven inflammation in diseases like rheumatoid arthritis.
Area of Science:
- Biochemistry
- Immunology
- Molecular Biology
Background:
- PRELP (proteoglycan) is found in cartilage and basement membranes.
- In rheumatoid arthritis (RA), PRELP is released into synovial fluid.
- Previous studies suggested PRELP interacts with C4b-binding protein to regulate complement.
Purpose of the Study:
- To investigate the direct role of PRELP in complement system regulation.
- To elucidate the mechanism by which PRELP inhibits complement activation.
Main Methods:
- Investigated PRELP's interaction with complement component C9.
- Assessed PRELP's effect on membrane attack complex (MAC) formation.
- Examined PRELP's interaction with complement component C3 and C3-convertase.
Main Results:
- PRELP directly inhibits all complement pathways.
- PRELP binds C9, preventing MAC formation by inhibiting C9 polymerization.
- PRELP interacts with C3, inhibiting alternative pathway C3-convertase formation.
Conclusions:
- PRELP acts as a direct inhibitor of the complement system.
- PRELP's inhibition of MAC and C3-convertase formation suggests a role in limiting inflammation.
- PRELP may protect basement membranes and cartilage from complement-mediated damage in inflammatory diseases like RA.
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