title: EGL-20/Wnt and MAB-5/Hox Act Sequentially to Inhibit Anterior Migration of Neuroblasts in C. elegans.
abstract: Directed neuroblast and neuronal migration is important in the proper development of nervous systems. In C. elegans the bilateral Q neuroblasts QR (on the right) and QL (on the left) undergo an identical pattern of cell division and differentiation but migrate in opposite directions (QR and descendants anteriorly and QL and descendants posteriorly). EGL-20/Wnt, via canonical Wnt signaling, drives the expression of MAB-5/Hox in QL but not QR. MAB-5 acts as a determinant of posterior migration, and mab-5 and egl-20 mutants display anterior QL descendant migrations. Here we analyze the behaviors of QR and QL descendants as they begin their anterior and posterior migrations, and the effects of EGL-20 and MAB-5 on these behaviors. The anterior and posterior daughters of QR (QR.a/p) after the first division immediately polarize and begin anterior migration, whereas QL.a/p remain rounded and non-migratory. After ~1 hour, QL.a migrates posteriorly over QL.p. We find that in egl-20/Wnt, bar-1/β-catenin, and mab-5/Hox mutants, QL.a/p polarize and migrate anteriorly, indicating that these molecules normally inhibit anterior migration of QL.a/p. In egl-20/Wnt mutants, QL.a/p immediately polarize and begin migration, whereas in bar-1/β-catenin and mab-5/Hox, the cells transiently retain a rounded, non-migratory morphology before anterior migration. Thus, EGL-20/Wnt mediates an acute inhibition of anterior migration independently of BAR-1/β-catenin and MAB-5/Hox, and a later, possible transcriptional response mediated by BAR-1/β-catenin and MAB-5/Hox. In addition to inhibiting anterior migration, MAB-5/Hox also cell-autonomously promotes posterior migration of QL.a (and QR.a in a mab-5 gain-of-function).
authors: Programs in Genetics and Molecular, Cellular and Developmental Biology, Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66045, United States of America.
authors: Matthew P
authors: MP
authors: Josephson
authors: School of Life Sciences, Tsinghua University, Beijing, 100084, China.
authors: Yongping
authors: Y
authors: Chai
authors: School of Life Sciences, Tsinghua University, Beijing, 100084, China.
authors: Guangshuo
authors: G
authors: Ou
authors: Programs in Genetics and Molecular, Cellular and Developmental Biology, Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66045, United States of America.
authors: Erik A
authors: EA
authors: Lundquist
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000502:physiology*; D002455:Cell Division; D002465:Cell Movement; D006023:Glycoproteins / Q000502:physiology*; D018398:Homeodomain Proteins / Q000502:physiology*; D058953:Neural Stem Cells / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D051153:Wnt Proteins; D060449:Wnt Signaling Pathway
chemical_list: D029742:Caenorhabditis elegans Proteins; C117259:Egl-20 protein, C elegans; D006023:Glycoproteins; D018398:Homeodomain Proteins; C081538:Mab-5 protein, C elegans; D014157:Transcription Factors; D051153:Wnt Proteins