Identification of evolutionarily conserved promoter elements and amino acids required for function of the C. elegans beta-catenin homolog BAR-1.
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.
Natarajan
L
L
Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
Jackson
B M
BM
Szyleyko
E
E
Eisenmann
D M
DM
D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D017124:Conserved Sequence; D003598:Cytoskeletal Proteins / Q000235:genetics; D019143:Evolution, Molecular; D005260:Female; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009474:Neurons / Q000502:physiology; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics; D014844:Vulva / Q000254:growth & development; D051176:beta Catenin
D029742:Caenorhabditis elegans Proteins; D003598:Cytoskeletal Proteins; D008164:Luminescent Proteins; D011506:Proteins; D015534:Trans-Activators; C115014:bar-1 protein, C elegans; D051176:beta Catenin; D049452:Green Fluorescent Proteins