C. elegans POP-1/TCF functions in a canonical Wnt pathway that controls cell migration and in a noncanonical Wnt pathway that controls cell polarity.
In Caenorhabditis elegans, Wnt signaling pathways are important in controlling cell polarity and cell migrations. In the embryo, a novel Wnt pathway functions through a (beta)-catenin homolog, WRM-1, to downregulate the levels of POP-1/Tcf in the posterior daughter of the EMS blastomere. The level of POP-1 is also lower in the posterior daughters of many anteroposterior asymmetric cell divisions during development. I have found that this is the case for of a pair of postembryonic blast cells in the tail. In wild-type animals, the level of POP-1 is lower in the posterior daughters of the two T cells, TL and TR. Furthermore, in lin-44/Wnt mutants, in which the polarities of the T cell divisions are frequently reversed, the level of POP-1 is frequently lower in the anterior daughters of the T cells. I have used a novel RNA-mediated interference technique to interfere specifically with pop-1 zygotic function and have determined that pop-1 is required for wild-type T cell polarity. Surprisingly, none of the three C. elegans (beta)-catenin homologs appeared to function with POP-1 to control T cell polarity. Wnt signaling by EGL-20/Wnt controls the migration of the descendants of the QL neuroblast by regulating the expression the Hox gene mab-5. Interfering with pop-1 zygotic function caused defects in the migration of the QL descendants that mimicked the defects in egl-20/Wnt mutants and blocked the expression of mab-5. This suggests that POP-1 functions in the canonical Wnt pathway to control QL descendant migration and in novel Wnt pathways to control EMS and T cell polarities.
Herman
M
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Program in Molecular, Cellular and Developmental Biology, Division of Biology, Kansas State University, Manhattan, KS 66506, USA. mherman@ksu.edu
D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins; D019070:Cell Lineage; D002465:Cell Movement; D016764:Cell Polarity; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013623:Tail / Q000166:cytology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D015053:Zygote / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; C117259:Egl-20 protein, C elegans; D006023:Glycoproteins; D006609:High Mobility Group Proteins; D018398:Homeodomain Proteins; C081538:Mab-5 protein, C elegans; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D051153:Wnt Proteins; D029961:Zebrafish Proteins; C096787:pop-1 protein, C elegans; D012313:RNA