Genomic analysis of immunity in a Urochordate and the emergence of the vertebrate immune system: "waiting for Godot"

Kaoru Azumi, Rosaria De Santis, Anthony De Tomaso, Isidore Rigoutsos, Fumiko Yoshizaki, Maria Rosaria Pinto, Rita Marino, Kazuhito Shida, Makoto Ikeda, Masami Ikeda, Masafumi Arai, Yasuhito Inoue, Toshio Shimizu, Nori Satoh, Daniel S. Rokhsar, Louis Du Pasquier, Masanori Kasahara, Masanobu Satake, Masaru Nonaka

Research output: Contribution to journalArticlepeer-review

236 Citations (Scopus)

Abstract

Genome-wide sequence analysis in the invertebrate chordate, Ciona intestinalis, has provided a comprehensive picture of immune-related genes in an organism that occupies a key phylogenetic position in vertebrate evolution. The pivotal genes for adaptive immunity, such as the major histocompatibility complex (MHC) class I and II genes, T-cell receptors, or dimeric immunoglobulin molecules, have not been identified in the Ciona genome. Many genes involved in innate immunity have been identified, including complement components, Toll-like receptors, and the genes involved in intracellular signal transduction of immune responses, and show both expansion and unexpected diversity in comparison with the vertebrates. In addition, a number of genes were identified which predicted integral membrane proteins with extracellular C-type lectin or immunoglobulin domains and intracellular immunoreceptor tyrosine-based inhibitory motifs (ITIMs) and immunoreceptor tyrosine-based activation motifs (ITAMs) (plus their associated signal transduction molecules), suggesting that activating and inhibitory receptors have an MHC-independent function and an early evolutionary origin. A crucial component of vertebrate adaptive immunity is somatic diversification, and the recombination activating genes (RAG) and activation-induced cytidine deaminase (AID) genes responsible for the Generation of diversity are not present in Ciona. However, there are key V regions, the essential feature of an immunoglobulin superfamily VC1-like core, and possible proto-MHC regions scattered throughout the genome waiting for Godot.

Original languageEnglish
Pages (from-to)570-581
Number of pages12
JournalImmunogenetics
Volume55
Issue number8
DOIs
Publication statusPublished - 2003 Nov 1

Keywords

  • Evolution
  • Genome analysis
  • Immunological genes
  • Urochordate

ASJC Scopus subject areas

  • Immunology
  • Genetics

Fingerprint Dive into the research topics of 'Genomic analysis of immunity in a Urochordate and the emergence of the vertebrate immune system: "waiting for Godot"'. Together they form a unique fingerprint.

Cite this