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Evolution of trappin genes in mammals
Akira Kato1, Alejandro P Rooney, Yutaka Furutani
1Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, Japan. akirkato@bio.titech.ac.jp
BMC Evolutionary Biology
|February 2, 2010
Summary
Trappin gene duplications vary across mammals, with evidence of ancient duplication in Afrotheria and more recent events in armadillos, pigs, and cows. These findings highlight the dynamic evolution of host-defense peptides in eutherian genomes.
Area of Science:
- Genomics
- Evolutionary Biology
- Immunology
Background:
- Trappin is a host-defense peptide with antiproteolytic, anti-inflammatory, and antimicrobial functions.
- Gene copy number and composition of trappin paralogs differ significantly across mammalian species.
- Previous observations indicated recent trappin gene duplications in pigs and cows.
Purpose of the Study:
- To investigate the evolutionary patterns of trappin gene duplications across mammalian lineages.
- To determine if trappin gene duplications are lineage-specific or widespread.
- To date the evolutionary events of trappin gene duplication.
Main Methods:
- Analysis of recently developed genome databases for trappin gene presence and duplication.
- Bayesian phylogenetic analysis to estimate duplication event timing.
- Comparative analysis of coding and non-coding regions to assess evolutionary rates.
Main Results:
- Duplicated trappin multigenes were identified in the nine-banded armadillo and anciently in Afrotherian species (elephant, tenrec, hyrax).
- A single trappin-2 gene was common in eutherian species; no typical trappin gene was found in birds or opossums.
- Duplication events were dated, with Afrotheria at 244 Mya and armadillo, cow, and pig more recently (35, 13, and 3 Mya, respectively).
- Accelerated evolution and positive Darwinian selection were observed in pig-specific trappin paralogs.
Conclusions:
- Trappin appears to be a eutherian-specific molecule.
- Eutherian genomes possess a significant capacity for generating trappin multigene families.
- The study reveals diverse evolutionary trajectories for trappin genes across mammals.
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