Roles of the Homothorax/Meis/Prep Homolog UNC-62 and the Exd/Pbx Homologs CEH-20 and CEH-40 in C. Elegans Embryogenesis

Development. 2002 Nov;129(22):5255-68.


Co-factor homeodomain proteins such as Drosophila Homothorax (Hth) and Extradenticle (Exd) and their respective vertebrate homologs, the Meis/Prep and Pbx proteins, can increase the DNA-binding specificity of Hox protein transcription factors and appear to be required for many of their developmental functions. We show that the unc-62 gene encodes the C. elegans ortholog of Hth, and that maternal-effect unc-62 mutations can cause severe posterior disorganization during embryogenesis (Nob phenotype), superficially similar to that seen in embryos lacking function of either the two posterior-group Hox genes nob-1 and php-3 or the caudal homolog pal-1. Other zygotically acting unc-62 alleles cause earlier embryonic arrest or incompletely penetrant larval lethality with variable morphogenetic defects among the survivors, suggesting that unc-62 functions are required at several stages of development. The differential accumulation of four unc-62 transcripts is consistent with multiple functions. The C. elegans exd homologs ceh-20 and ceh-40 interact genetically with unc-62 and may have overlapping roles in embryogenesis: neither CEH-20 nor CEH-40 appears to be required when the other is present, but loss of both functions causes incompletely penetrant embryonic lethality in the presence of unc-62(+) and complete embryonic lethality in the presence of an unc-62 hypomorphic allele.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alternative Splicing
  • Amino Acid Sequence
  • Animals
  • Caenorhabditis elegans / embryology*
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Drosophila Proteins / genetics
  • Embryo, Nonmammalian
  • Fetal Death / genetics
  • Gene Expression Regulation, Developmental
  • Helminth Proteins / genetics
  • Helminth Proteins / metabolism*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Molecular Sequence Data
  • Multigene Family
  • Mutation
  • Myeloid Ecotropic Viral Integration Site 1 Protein
  • Neoplasm Proteins / genetics
  • Phenotype
  • Sequence Homology, Amino Acid
  • Transcription Factors / genetics


  • Caenorhabditis elegans Proteins
  • Drosophila Proteins
  • Helminth Proteins
  • Homeodomain Proteins
  • Myeloid Ecotropic Viral Integration Site 1 Protein
  • Neoplasm Proteins
  • Transcription Factors
  • Unc-62 protein, C elegans
  • ceh-20 protein, C elegans
  • exd protein, Drosophila
  • hth protein, Drosophila

Associated data

  • GENBANK/AF427474
  • GENBANK/AF427475
  • GENBANK/AF427476
  • GENBANK/AF427477