In insects and crustaceans, thousands of Down syndrome cell adhesion molecules (Dscam) can be generated by alternative splicing of variable exons from a single-locus gene, Dscam-hv. This extraordinarily versatile gene (38,016 protein isoforms produced in Drosophila) was first proposed to be involved in exon guidance and subsequently implicated in immunity as a hypervariable immune molecule. Almost 20 y after discovery of Dscam-hv, there have been many studies in insects and crustaceans regarding roles of Dscam in immunity, with many similarities and concurrently, many differences. Here, we review the current status of Dscam-hv, presented as a comparison of similarities and differences in insects and crustaceans and discuss hypotheses of Dscam functions in immunity.
Keywords: Crustaceans; Dscam; Immune priming; Innate immune memory; Insects; Invertebrate immunity.
Copyright © 2019 Elsevier Ltd. All rights reserved.
The evolution of Dscam genes across the arthropods.BMC Evol Biol. 2012 Apr 13;12:53. doi: 10.1186/1471-2148-12-53. BMC Evol Biol. 2012. PMID: 22500922 Free PMC article.
The Dscam homologue of the crustacean Daphnia is diversified by alternative splicing like in insects.Mol Biol Evol. 2008 Jul;25(7):1429-39. doi: 10.1093/molbev/msn087. Epub 2008 Apr 9. Mol Biol Evol. 2008. PMID: 18403399
Dscam and pancrustacean immune memory - a review of the evidence.Dev Comp Immunol. 2015 Feb;48(2):315-23. doi: 10.1016/j.dci.2014.03.004. Epub 2014 Mar 19. Dev Comp Immunol. 2015. PMID: 24657209 Review.
More than one way to produce protein diversity: duplication and limited alternative splicing of an adhesion molecule gene in basal arthropods.Evolution. 2013 Oct;67(10):2999-3011. doi: 10.1111/evo.12179. Epub 2013 Jul 4. Evolution. 2013. PMID: 24094349
Somatic and Germline Diversification of a Putative Immunoreceptor within One Phylum: Dscam in Arthropods.Results Probl Cell Differ. 2015;57:131-58. doi: 10.1007/978-3-319-20819-0_6. Results Probl Cell Differ. 2015. PMID: 26537380 Review.