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Identification and functional characterization of a new gene encoding the mouse terminal complement inhibitor CD59
1Center for Experimental Therapeutics and Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|August 18, 2000
Summary
Researchers discovered a new mouse CD59 gene, cd59b, which inhibits complement-mediated cell lysis. This gene is primarily expressed in the testes, unlike cd59a, suggesting distinct physiological roles.
Area of Science:
- Immunology
- Molecular Biology
- Genetics
Background:
- CD59 is a GPI-anchored protein regulating complement cascade terminal step.
- It prevents membrane attack complex (MAC) formation by inhibiting C9 binding.
- Previous studies identified single CD59 genes in humans, rats, mice, and pigs.
Purpose of the Study:
- To discover and functionally characterize a second CD59 gene in mice.
- To investigate the expression patterns and functional activity of this novel gene.
Main Methods:
- Gene discovery and sequence analysis.
- cDNA transfection into Chinese hamster ovary (CHO) cells.
- Flow cytometry and phosphatidylinositol-specific phospholipase C (PI-PLC) cleavage assays.
- Complement-mediated lysis assays.
- Northern blot analysis for gene expression.
Main Results:
- A novel mouse CD59 gene, cd59b, was identified, showing 85% nucleotide and 63% amino acid identity to cd59a.
- cd59b encodes a GPI-anchored protein expressed on the cell surface and susceptible to PI-PLC cleavage.
- CHO cells expressing cd59b exhibited resistance to complement-mediated lysis.
- cd59b expression is selective to mouse testes, whereas cd59a is widely expressed in other organs.
Conclusions:
- Mouse cd59b encodes a functional MAC inhibitor.
- Differential regulation and tissue-specific expression of cd59a and cd59b suggest distinct physiological functions.
- The discovery of two CD59 genes in mice expands our understanding of complement regulation.