title: ELT-5 and ELT-6 are required continuously to regulate epidermal seam cell differentiation and cell fusion in C. elegans.
abstract: The C. elegans epidermis is a simple epithelium comprised of three major cell types, the seam, syncytial and P cells. While specification of all major epidermal cells is known to require the ELT-1 GATA transcription factor, little is known about how the individual epidermal cell types are specified. We report that elt-5 and -6, adjacent genes encoding GATA factors, are essential for the development of the lateral epidermal cells, the seam cells. Inhibition of elt-5 and -6 function by RNA-mediated interference results in penetrant late embryonic and early larval lethality. Seam cells in affected animals do not differentiate properly: the alae, seam-specific cuticular structures, are generally absent and expression of several seam-specific markers is blocked. In addition, elt-3, which encodes another GATA factor normally expressed in non-seam epidermis, is often ectopically expressed in the seam cells of affected animals, demonstrating that ELT-5 and -6 repress elt-3 expression in wild-type seam cells. Seam cells in affected animals often undergo inappropriate fusion with the epidermal syncytia. Interference of elt-5 and -6 function during larval development can cause fusion of all seam cells with the surrounding syncytia and pronounced defects in molting. elt-5 and -6 are both expressed in seam cells and many other cells, and are apparently functionally interchangeable. Their expression is controlled by separable tissue-specific regulatory elements and the apportionment of monocistronic versus dicistronic transcription of both genes appears to be subject to cell-type-specific regulation. Collectively, these findings indicate that elt-5 and -6 function continuously throughout C. elegans development to regulate seam cell differentiation and cell fusion.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA.
authors.forename: K
authors.initials: K
authors.lastname: Koh
authors.forename: J H
authors.initials: JH
authors.lastname: Rothman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins; D002454:Cell Differentiation / Q000502:physiology; D002459:Cell Fusion; D019070:Cell Lineage / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004742:Enhancer Elements, Genetic; D004847:Epithelial Cells / Q000166:cytology*; D050980:GATA Transcription Factors; D018507:Gene Expression Regulation, Developmental; D020043:Genes, Essential; D017238:Genes, Helminth; D017930:Genes, Reporter; D005819:Genetic Markers; D015801:Helminth Proteins / Q000235:genetics / Q000502:physiology*; D007814:Larva; D008969:Molecular Sequence Data; D018510:RNA, Helminth; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D050980:GATA Transcription Factors; D005819:Genetic Markers; D015801:Helminth Proteins; D018510:RNA, Helminth; D012333:RNA, Messenger; D014157:Transcription Factors; C434745:egl-18 protein, C elegans; C434746:elt-6 protein, C elegans