Identification of evolutionarily conserved promoter elements and amino acids required for function of the C. elegans beta-catenin homolog BAR-1

Dev Biol. 2004 Aug 15;272(2):536-57. doi: 10.1016/j.ydbio.2004.05.027.

Abstract

beta-catenins are conserved transcription factors regulated posttranslationally by Wnt signaling. bar-1 encodes a Caenorhabditis elegans beta-catenin acting in multiple Wnt-mediated processes, including cell fate specification by vulval precursor cells (VPCs) and migration of the Q(L) neuroblast progeny. We took two approaches to extend our knowledge of bar-1 function. First, we undertook a bar-1 promoter analysis using transcriptional GFP reporter fusions and found that bar-1 expression is regulated in specific cells at the transcriptional level. We identified promoter elements necessary for bar-1 expression in several cell types, including a 321-bp element sufficient for expression in ventral cord neurons (VCNs) and a 1.1-kb element sufficient for expression in the developing vulva and adult seam cells. Expression of bar-1 from the 321-bp element rescued the Uncoordinated (Unc) phenotype of bar-1 mutants, but not the vulval phenotype, suggesting that a Wnt pathway may act in ventral cord neurons to mediate proper locomotion. By comparison of the 1.1-kb element to homologous sequences from Caenorhabditis briggsae, we identified evolutionarily conserved sequences necessary for expression in vulval or seam cells. Second, we analyzed 24 mutations in bar-1 and identified several residues required for BAR-1 activity in C. elegans. By phylogenetic comparison, we found that most of these residues are conserved and may identify amino acids necessary for beta-catenin function in all species.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Genetically Modified
  • Base Sequence
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans Proteins / genetics*
  • Caenorhabditis elegans Proteins / metabolism
  • Conserved Sequence
  • Cytoskeletal Proteins / genetics
  • Evolution, Molecular
  • Female
  • Gene Expression Regulation, Developmental
  • Green Fluorescent Proteins
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Molecular Sequence Data
  • Mutation
  • Neurons / physiology
  • Phylogeny
  • Promoter Regions, Genetic / genetics*
  • Proteins / genetics*
  • Proteins / metabolism
  • Regulatory Sequences, Nucleic Acid
  • Signal Transduction
  • Trans-Activators / genetics
  • Vulva / growth & development
  • beta Catenin

Substances

  • Caenorhabditis elegans Proteins
  • Cytoskeletal Proteins
  • Luminescent Proteins
  • Proteins
  • Trans-Activators
  • bar-1 protein, C elegans
  • beta Catenin
  • Green Fluorescent Proteins