title: Islet is a key determinant of ascidian palp morphogenesis.
abstract: The anterior-most ectoderm of ascidian larvae contains the adhesive papillae, or palps, which play an important role in triggering the metamorphosis of swimming tadpoles. In Ciona intestinalis, the palps consist of three conical protrusions within a field of thickened epithelium that form late in embryogenesis, as tailbuds mature into larvae. The palp protrusions express the LIM-homeodomain transcription factor Islet. Protrusion occurs through differential cell elongation, probably mediated by Islet, as we find that ectopic expression of Islet is sufficient to promote cell lengthening. FGF signaling is required for both Islet expression and palp morphogenesis. Importantly, we show that Islet expression can rescue the palp-deficient phenotype that results from inhibition of FGF signaling. We conclude that Islet is a key regulatory factor governing morphogenesis of the palps. It is conceivable that Islet is also essential for the cellular morphogenesis of placode-derived sensory neurons in vertebrates.
authors.affiliation: Center for Integrative Genomics, Division of Genetics, Genomics, and Development, Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA.
authors.forename: Eileen
authors.initials: E
authors.lastname: Wagner
authors.affiliation: New York University, Center for Developmental Genetics, Department of Biology, 1009 Silver Center, 100 Washington Square East, New York, NY 10003-6688, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Stolfi
authors.affiliation: Functional Genomics Laboratory, Department of Molecular and Cell Biology, University of California-Berkeley, 255 Life Sciences Addition #3200, Berkeley, CA 94720-3200, USA.
authors.forename: Yoon
authors.initials: Y
authors.lastname: Gi Choi
authors.affiliation: Center for Integrative Genomics, Division of Genetics, Genomics, and Development, Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA mlevine@berkeley.edu.
authors.forename: Mike
authors.initials: M
authors.lastname: Levine
mesh_terms: D000818:Animals; D048430:Cell Shape; D002938:Ciona intestinalis / Q000196:embryology* / Q000502:physiology; D005346:Fibroblast Growth Factors / Q000378:metabolism; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D060850:LIM-Homeodomain Proteins / Q000378:metabolism*; D009024:Morphogenesis; D009474:Neurons / Q000378:metabolism; D010641:Phenotype; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D060850:LIM-Homeodomain Proteins; D014157:Transcription Factors; C063843:insulin gene enhancer binding protein Isl-1; D005346:Fibroblast Growth Factors
keywords: Ascidian; Cell shape; Islet; LIM domain; Palps; Placode