A large family of Dscam genes with tandemly arrayed 5' cassettes in Chelicerata

Nat Commun. 2016 Apr 15:7:11252. doi: 10.1038/ncomms11252.

Abstract

Drosophila Dscam1 (Down Syndrome Cell Adhesion Molecules) and vertebrate clustered protocadherins (Pcdhs) are two classic examples of the extraordinary isoform diversity from a single genomic locus. Dscam1 encodes 38,016 distinct isoforms via mutually exclusive splicing in D. melanogaster, while the vertebrate clustered Pcdhs utilize alternative promoters to generate isoform diversity. Here we reveal a shortened Dscam gene family with tandemly arrayed 5' cassettes in Chelicerata. These cassette repeats generally comprise two or four exons, corresponding to variable Immunoglobulin 7 (Ig7) or Ig7-8 domains of Drosophila Dscam1. Furthermore, extraordinary isoform diversity has been generated through a combination of alternating promoter and alternative splicing. These sDscams have a high sequence similarity with Drosophila Dscam1, and share striking organizational resemblance to the 5' variable regions of vertebrate clustered Pcdhs. Hence, our findings have important implications for understanding the functional similarities between Drosophila Dscam1 and vertebrate Pcdhs, and may provide further mechanistic insights into the regulation of isoform diversity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing*
  • Amino Acid Sequence
  • Animals
  • Arthropod Proteins / classification
  • Arthropod Proteins / genetics*
  • Arthropods / classification
  • Arthropods / genetics*
  • Base Sequence
  • Cell Adhesion Molecules / classification
  • Cell Adhesion Molecules / genetics*
  • Gene Expression
  • Genetic Variation
  • Models, Genetic
  • Molecular Sequence Data
  • Multigene Family
  • Phylogeny
  • Protein Isoforms / classification
  • Protein Isoforms / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Species Specificity

Substances

  • Arthropod Proteins
  • Cell Adhesion Molecules
  • Protein Isoforms