Original Article

Development Genes and Evolution

, Volume 213, Issue 5, pp 303-313

First online:

A genomewide survey of developmentally relevant genes in Ciona intestinalis

X. Genes for cell junctions and extracellular matrix
  • Yasunori SasakuraAffiliated withDepartment of Zoology, Graduate School of Science, Kyoto University
  • , Eiichi ShoguchiAffiliated withDepartment of Zoology, Graduate School of Science, Kyoto University
  • , Naohito TakatoriAffiliated withDepartment of Zoology, Graduate School of Science, Kyoto University
  • , Shuichi WadaAffiliated withDepartment of Zoology, Graduate School of Science, Kyoto University
  • , Ian A. MeinertzhagenAffiliated withLife Sciences Centre, Dalhousie University
  • , Yutaka SatouAffiliated withDepartment of Zoology, Graduate School of Science, Kyoto University
  • , Nori SatohAffiliated withDepartment of Zoology, Graduate School of Science, Kyoto University Email author 

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

Cell junctions and the extracellular matrix (ECM) are crucial components in intercellular communication. These systems are thought to have become highly diversified during the course of vertebrate evolution. In the present study, we have examined whether the ancestral chordate already had such vertebrate systems for intercellular communication, for which we have searched the genome of the ascidian Ciona intestinalis. From this molecular perspective, the Ciona genome contains genes that encode protein components of tight junctions, hemidesmosomes and connexin-based gap junctions, as well as of adherens junctions and focal adhesions, but it does not have those for desmosomes. The latter omission is curious, and the ascidian type-I cadherins may represent an ancestral form of the vertebrate type-I cadherins and desmosomal cadherins, while Ci-Plakin may represent an ancestral protein of the vertebrate desmoplakins and plectins. If this is the case, then ascidians may have retained ancestral desmosome-like structures, as suggested by previous electron-microscopic observations. In addition, ECM genes that have been regarded as vertebrate-specific were also found in the Ciona genome. These results suggest that the last common ancestor shared by ascidians and vertebrates, the ancestor of the entire chordate clade, had essentially the same systems of cell junctions as those in extant vertebrates. However, the number of such genes for each family in the Ciona genome is far smaller than that in vertebrate genomes. In vertebrates these ancestral cell junctions appear to have evolved into more diverse, and possibly more complex, forms, compared with those in their urochordate siblings.

Keywords

Basal chordates Ciona intestinalis Genomewide survey Genes Cell junctions