title: A conserved role for the MEK signalling pathway in neural tissue specification and posteriorisation in the invertebrate chordate, the ascidian Ciona intestinalis.
abstract: Ascidians are invertebrate chordates with a larval body plan similar to that of vertebrates. The ascidian larval CNS is divided along the anteroposterior axis into sensory vesicle, neck, visceral ganglion and tail nerve cord. The anterior part of the sensory vesicle comes from the a-line animal blastomeres, whereas the remaining CNS is largely derived from the A-line vegetal blastomeres. We have analysed the role of the Ras/MEK/ERK signalling pathway in the formation of the larval CNS in the ascidian, Ciona intestinalis. We show evidence that this pathway is required, during the cleavage stages, for the acquisition of: (1) neural fates in otherwise epidermal cells (in a-line cells); and (2) the posterior identity of tail nerve cord precursors that otherwise adopt a more anterior neural character (in A-line cells). Altogether, the MEK signalling pathway appears to play evolutionary conserved roles in these processes in ascidians and vertebrates, suggesting that this may represent an ancestral chordate strategy.
authors.affiliation: Laboratoire de Génétique et Physiologie du Développement, IBDM, CNRS/INSERM/Université de la Méditerranée/AP de Marseille, Parc Scientifique de Luminy, Case 907, 13288, Marseille Cedex 9, France. clare.hudson@obs-vlfr.fr
authors.forename: Clare
authors.initials: C
authors.lastname: Hudson
authors.forename: Sébastien
authors.initials: S
authors.lastname: Darras
authors.forename: Danielle
authors.initials: D
authors.lastname: Caillol
authors.forename: Hitoyoshi
authors.initials: H
authors.lastname: Yasuo
authors.forename: Patrick
authors.initials: P
authors.lastname: Lemaire
mesh_terms: D000818:Animals; D001549:Benzamides; D001757:Blastomeres / Q000378:metabolism; D019521:Body Patterning / Q000502:physiology*; D002070:Butadienes / Q000494:pharmacology; D002454:Cell Differentiation; D002490:Central Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002938:Ciona intestinalis / Q000187:drug effects / Q000196:embryology / Q000254:growth & development*; D004625:Embryo, Nonmammalian / Q000187:drug effects; D004627:Embryonic Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D005346:Fibroblast Growth Factors / Q000187:drug effects / Q000378:metabolism; D005775:Gastrula; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D007814:Larva; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D051857:Otx Transcription Factors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013623:Tail / Q000187:drug effects / Q000196:embryology
chemical_list: C120227:2-(2-chloro-4-iodophenylamino)-N-cyclopropylmethoxy-3,4-difluorobenzamide; D001549:Benzamides; D002070:Butadienes; D004791:Enzyme Inhibitors; D018398:Homeodomain Proteins; D009570:Nitriles; D051857:Otx Transcription Factors; C113580:U 0126; D016222:Fibroblast Growth Factor 2; D005346:Fibroblast Growth Factors; D017346:Protein Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; D016283:Proto-Oncogene Proteins p21(ras)