title: Knockdown of SKN-1 and the Wnt effector TCF/POP-1 reveals differences in endomesoderm specification in C. briggsae as compared with C. elegans.
abstract: In the nematode, C. elegans, the bZIP/homeodomain transcription factor SKN-1 and the Wnt effector TCF/POP-1 are central to the maternal specification of the endomesoderm prior to gastrulation. The 8-cell stage blastomere MS is primarily a mesodermal precursor, giving rise to cells of the pharynx and body muscle among others, while its sister E clonally generates the entire endoderm (gut). In C. elegans, loss of SKN-1 results in the absence of MS-derived tissues all of the time, and loss of gut most of the time, while loss of POP-1 results in a mis-specification of MS as an E-like cell, resulting in ectopic gut. We show that in C. briggsae, RNAi of skn-1 results in a stronger E defect but no apparent MS defect, while RNAi of pop-1 results in loss of gut and an apparent E to MS transformation, the opposite of the pop-1 knockdown phenotype seen in C. elegans. The difference in pop-1(-) phenotypes correlates with changes in how the endogenous endoderm-specifying end genes are regulated by POP-1 in the two species. Our results suggest that integration of Wnt-dependent and Wnt-independent cell fate specification pathways within the Caenorhabditis genus can occur in different ways.
authors.affiliation: Department of Biology, University of California, Riverside, Riverside, CA 92521, USA.
authors.forename: Katy Tan-Hui
authors.initials: KT
authors.lastname: Lin
authors.forename: Gina
authors.initials: G
authors.lastname: Broitman-Maduro
authors.forename: Wendy W K
authors.initials: WW
authors.lastname: Hung
authors.forename: Serena
authors.initials: S
authors.lastname: Cervantes
authors.forename: Morris F
authors.initials: MF
authors.lastname: Maduro
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D019521:Body Patterning; D002107:Caenorhabditis / Q000196:embryology* / Q000235:genetics; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000002:abnormalities / Q000378:metabolism; D004707:Endoderm / Q000002:abnormalities / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental; D006609:High Mobility Group Proteins / Q000378:metabolism*; D008648:Mesoderm / Q000196:embryology* / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D010614:Pharynx / Q000002:abnormalities; D010641:Phenotype; D034622:RNA Interference; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism*; D051153:Wnt Proteins / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D014157:Transcription Factors; D051153:Wnt Proteins; C096787:pop-1 protein, C elegans; C073702:skn-1 protein, C elegans