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Oligomeric structure and tissue distribution of ficolins from mouse, pig and human
1Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, 27710, USA.
Abstract:
Mouse plasma ficolin was purified by GlcNAc affinity and anion-exchange chromatography. Gel-filtration chromatography and gradient sedimentation indicated that mouse plasma ficolin is a 12-mer of approximately 35 kDa subunits, and electron microscopy showed the same parachute-like structure previously characterized for the pig ficolin 12-mer. Whereas the predominant form in pig plasma is a 24-mer, mouse and human plasma ficolin showed only the 12-mer form. We conclude that mouse plasma ficolin corresponds to the recently described ficolin A. We have identified a second mouse ficolin gene, ficolin B, which means that pig and mouse each have two ficolin genes, and human has three. One ficolin gene in all species is expressed in liver and is the primary source of plasma ficolin. Expression of this gene in other tissues, and expression of the second ficolin gene, appears to vary in different species.
Insights
Mouse plasma ficolin, a parachute-like structure, exists as a 12-mer, unlike pig ficolin. Researchers identified ficolin A and ficolin B genes, revealing species-specific expression patterns for plasma ficolin production.
Area of Science:
- Biochemistry
- Immunology
- Molecular Biology
Background:
- Ficolins are a family of pattern recognition molecules involved in innate immunity.
- Previous studies characterized pig ficolin as a 24-mer, but the structure of mouse plasma ficolin was less understood.
Purpose of the Study:
- To characterize the structure and composition of mouse plasma ficolin.
- To identify and compare ficolin genes across different species.
- To elucidate the expression patterns of ficolin genes.
Main Methods:
- Purification using GlcNAc affinity and anion-exchange chromatography.
- Structural analysis via gel-filtration chromatography, gradient sedimentation, and electron microscopy.
- Gene identification and expression analysis.
Main Results:
- Mouse plasma ficolin was purified and characterized as a 12-mer with a parachute-like structure, similar to pig ficolin.
- Mouse and human plasma ficolin predominantly exist as 12-mers, contrasting with the 24-mer form in pigs.
- A second mouse ficolin gene, ficolin B, was identified, bringing the total to two in mice and pigs, and three in humans.
- A conserved liver-expressed ficolin gene is the primary source of plasma ficolin, with variable expression of other genes across species.
Conclusions:
- Mouse plasma ficolin is identified as ficolin A, a 12-mer structure.
- The number of ficolin genes and their expression patterns in plasma differ across species.
- Understanding ficolin gene expression is crucial for comprehending innate immune responses.