title: Desmosomal cadherins in zebrafish epiboly and gastrulation.
abstract: BACKGROUND
  The desmosomal cadherins (DCs), desmocollin (Dsc) and desmoglein (Dsg), are the adhesion molecules of desmosomes, intercellular adhesive junctions of epithelia and cardiac muscle. Both the DCs and desmosomes have demonstrably essential roles in mammalian development. In order to initiate their study in a more tractable developmental system we have characterised zebrafish DCs and examined their roles in early zebrafish development.
  
  
  RESULTS
  We find that zebrafish possess one Dsc, the orthologue of mammalian Dsc1, which we designate zfDsc. Unlike mammalian Dscs, zfDsc exists only as the "a" form since it lacks the alternatively-spliced mini-exon that shortens the cytoplasmic domain to produce the "b" form. Zebrafish possess two Dsgs, designated zfDsgα and zfDsgβ, orthologues of mammalian Dsg2. They show 43.8% amino acid identity and the α form has a 43 amino acid glycine-rich sequence of unknown function in its extracellular domain. Both zfDsc and zfDsgα were present as maternal and zygotic transcripts whereas zfDsgβ was first expressed from 8 hours post-fertilisation (hpf). All three transcripts were present throughout subsequent stages of development. Morpholino knockdown of both zfDsc and zfDsgα expression produced similar defects in epiboly, axis elongation and somite formation, associated with abnormal desmosomes or reduced desmosome numbers.
  
  
  CONCLUSIONS
  These results demonstrate an important role for DCs and desmosomes in the early morphogenesis of the zebrafish embryo, provide a basis for more detailed analysis of their role and raise interesting questions relating to the evolution and functional significance of DC isoforms.
authors.affiliation: Faculty of Life Sciences, University of Manchester, (Michael Smith Building, Oxford Road), Manchester (M13 9PT), UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Goonesinghe
authors.forename: Xing-Ming
authors.initials: XM
authors.lastname: Luan
authors.forename: Adam
authors.initials: A
authors.lastname: Hurlstone
authors.forename: David
authors.initials: D
authors.lastname: Garrod
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051187:Desmocollins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051182:Desmogleins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003896:Desmosomes / Q000378:metabolism* / Q000648:ultrastructure; D005091:Exons; D005260:Female; D054262:Gastrulation; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics; D029961:Zebrafish Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D051187:Desmocollins; D051182:Desmogleins; D029961:Zebrafish Proteins; C572266:dsg2.1 protein, zebrafish; C572265:dsg2l protein, zebrafish