title: Vertical signalling involves transmission of Hox information from gastrula mesoderm to neurectoderm.
abstract: Development and patterning of neural tissue in the vertebrate embryo involves a set of molecules and processes whose relationships are not fully understood. Classical embryology revealed a remarkable phenomenon known as vertical signalling, a gastrulation stage mechanism that copies anterior-posterior positional information from mesoderm to prospective neural tissue. Vertical signalling mediates unambiguous copying of complex information from one tissue layer to another. In this study, we report an investigation of this process in recombinates of mesoderm and ectoderm from gastrulae of Xenopus laevis. Our results show that copying of positional information involves non cell autonomous autoregulation of particular Hox genes whose expression is copied from mesoderm to neurectoderm in the gastrula. Furthermore, this information sharing mechanism involves unconventional translocation of the homeoproteins themselves. This conserved primitive mechanism has been known for three decades but has only recently been put into any developmental context. It provides a simple, robust way to pattern the neurectoderm using the Hox pattern already present in the mesoderm during gastrulation. We suggest that this mechanism was selected during evolution to enable unambiguous copying of rather complex information from cell to cell and that it is a key part of the original ancestral mechanism mediating axial patterning by the highly conserved Hox genes.
authors.affiliation: Leiden University, Institute of Biology, Sylvius Laboratory, Leiden, The Netherlands.
authors.forename: Nabila
authors.initials: N
authors.lastname: Bardine
authors.affiliation: Leiden University, Institute of Biology, Sylvius Laboratory, Leiden, The Netherlands.
authors.forename: Gerda
authors.initials: G
authors.lastname: Lamers
authors.affiliation: University of Ulm, Institute of Biochemistry, Ulm, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Wacker
authors.affiliation: University of Ulm, Institute of Biochemistry, Ulm, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Donow
authors.affiliation: University of Ulm, Institute of Biochemistry, Ulm, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Knoechel
authors.affiliation: Leiden University, Institute of Biology, Sylvius Laboratory, Leiden, The Netherlands.
authors.forename: Antony
authors.initials: A
authors.lastname: Durston
mesh_terms: D000818:Animals; D005075:Biological Evolution; D019521:Body Patterning / Q000502:physiology*; D002450:Cell Communication / Q000502:physiology*; D017931:DNA Primers / Q000235:genetics; D004330:Drosophila; D005775:Gastrula / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D005801:Genes, Homeobox / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D060227:Imaginal Discs / Q000254:growth & development; D008648:Mesoderm / Q000502:physiology*; D054258:Neural Plate / Q000502:physiology*; D010590:Phalloidine; D014982:Xenopus laevis / Q000196:embryology*
chemical_list: D017931:DNA Primers; D049452:Green Fluorescent Proteins; D010590:Phalloidine