Related Experiment Videos
A novel chicken membrane-associated complement regulatory protein: molecular cloning and functional characterization
1Department of Immunology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
Journal of Immunology (Baltimore, Md. : 1950)
|December 21, 2000
Summary
Researchers identified chicken Cremp, a novel membrane complement regulatory protein. This protein protects host cells from homologous complement attack, suggesting a conserved protective mechanism across vertebrates.
Area of Science:
- Immunology
- Molecular Biology
- Genetics
Background:
- The complement system is a crucial part of innate immunity.
- Membrane-bound complement regulatory proteins (mCRPs) protect host cells from complement-mediated damage.
- The existence and function of mCRPs in non-mammalian vertebrates, particularly oviparous species, remain largely unexplored.
Purpose of the Study:
- To identify and characterize a novel membrane-associated complement regulatory protein in chickens.
- To investigate the structural and functional properties of this protein.
- To determine its role in protecting chicken cells from complement attack.
Main Methods:
- cDNA cloning and sequencing to identify the gene encoding the protein.
- Bioinformatic analysis to predict protein structure and homology.
- Transfection of Chinese hamster ovary (CHO) cells with the chicken cDNA.
- Complement-mediated cell lysis assays using homologous and heterologous complement.
- RNA blotting and immunoblotting to analyze mRNA and protein expression.
- Flow cytometry and immunofluorescence to confirm surface expression.
Main Results:
- A novel membrane-associated complement regulatory protein, named Cremp, was identified in chickens.
- Cremp shares structural similarities with human decay-accelerating factor (CD55) and membrane cofactor protein (CD46), suggesting an ancestral hybrid nature.
- Transfected cells expressing Cremp were protected from chicken complement but not from human or rabbit complement.
- Cremp mRNA and protein were ubiquitously expressed in all tested chicken organs.
- Surface expression of Cremp was confirmed on chicken cells.
Conclusions:
- Chicken Cremp functions as a membrane-bound regulator of the complement system.
- It specifically protects host cells from homologous complement attack.
- The findings suggest that membrane complement regulatory proteins are essential for host cell protection in non-mammalian vertebrates, indicating an ancient evolutionary origin of this protective mechanism.