title: Transcription factors GATA/ELT-2 and forkhead/HNF-3/PHA-4 regulate the tropomyosin gene expression in the pharynx and intestine of Caenorhabditis elegans.
abstract: Gene regulation during development is an important biological activity that leads to synthesis of biomolecules at specific locations and specific times. The single tropomyosin gene of Caenorhabditis elegans, tmy-1/lev-11, produces four isoforms of protein: two from the external promoter and two from the internal promoter. We investigated the internal promoter of tropomyosin to identify sequences that regulate expression of tmy-1 in the pharynx and intestine. By promoter deletion of tmy-1 reporters as well as by database analyses, a 100-bp fragment that contained binding sequences for a GATA factor, for a chicken CdxA homolog, and for a forkhead factor was identified. Both the forkhead and CdxA binding sequences contributed to pharyngeal and intestinal expression. In addition, the GATA site also influenced intestinal expression of tmy-1 reporter. We showed that ELT-2 and PHA-4 proteins interact directly with the GATA and forkhead binding sequences, respectively, in gel mobility shift assays. RNA interference knockdown of elt-2 diminished tmy-1::gfp expression in the intestine. In contrast to RNA interference knockdown of pha-4, expression of tmy-1::gfp in pha-4;smg-1 mutants was slightly weaker than that of the wild type. Ectopic expression of PHA-4 and ELT-2 by heat shock was sufficient to elicit widespread expression of tmy-1::lacZ reporter in embryos. We found no indication of a synergistic relation between ELT-2 and PHA-4. Based on our data, PHA-4 and CdxA function as general transcription factors for pharyngeal and intestinal regulation of tmy-1. We present models by which ELT-2, PHA-4, and CdxA orchestrate expression from the internal promoter of tmy-1.
authors.affiliation: Division of Bioscience, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
authors.forename: Frederick
authors.initials: F
authors.lastname: Anokye-Danso
authors.forename: Akwasi
authors.initials: A
authors.lastname: Anyanful
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Sakube
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kagawa
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D030161:Avian Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000033:anatomy & histology / Q000196:embryology / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D019070:Cell Lineage; D002645:Chickens; D050980:GATA Transcription Factors / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D007422:Intestines / Q000033:anatomy & histology / Q000502:physiology*; D008969:Molecular Sequence Data; D010614:Pharynx / Q000033:anatomy & histology / Q000502:physiology*; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014335:Tropomyosin / Q000235:genetics / Q000378:metabolism
chemical_list: D030161:Avian Proteins; D029742:Caenorhabditis elegans Proteins; C084100:CdxA protein, Gallus gallus; C094134:ELT-2 protein, C elegans; D050980:GATA Transcription Factors; D018398:Homeodomain Proteins; C113277:Pha-4 protein, C elegans; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014335:Tropomyosin