title: Expression profiles and unc-27 mutation rescue of the striated muscle type troponin I isoform-3 in Caenorhabditis elegans.
abstract: Transcription control of multiple genes in tissue- and stage-specific patterns is still of major interest. We show here that troponin I (TNI) is expressed under the control of upstream non-coding sequences and had functions as an isoform of intermediate type between pharynx and body-wall of the gene. In Caenorhabditis elegans, three striated muscle TNIs are expressed in body-wall muscles and a cardiac isoform is expressed in the pharynx. We have analyzed the gene expression mechanisms of tni-3 gene and motility function of its protein product. Promoter deletion analysis of the tni-3 gene identified muscle enhancers including the head enhancer. The CBF1/Su(H)/LAG-1-binding motif was included in the head enhancer. Yeast one-hybrid screening isolated the lag-1 clone in five candidates. Functional differences between the three striated muscle TNIs were investigated by the expression of promoter-fusion genes into tni-2/unc-27(e155) null mutant animals. The results suggest that the cis-elements in the promoters of the three genes are important for their tissue-specific expression and that from the function of TNI-3, the tni-3 gene would be an intermediate in the evolution of these genes by gene duplication. Mechanisms of tni-3 expression and its molecular function may contribute to our understanding of gene evolution and developmental programs.
authors.affiliation: Division of Bioscience, Graduate School of Natural Science and Technology, Okayama University, 　Okayama 700-8530, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Takashima
authors.forename: Shun
authors.initials: S
authors.lastname: Kitaoka
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Bando
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kagawa
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D004742:Enhancer Elements, Genetic; D019143:Evolution, Molecular; D006321:Heart; D008969:Molecular Sequence Data; D054792:Muscle, Striated / Q000378:metabolism*; D009154:Mutation; D009928:Organ Specificity; D010614:Pharynx; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D019210:Troponin I / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; C099355:LAG-1 protein, C elegans; D020033:Protein Isoforms; D019210:Troponin I; C581715:troponin I, C elegans