title: Lens and retina formation require expression of Pitx3 in Xenopus pre-lens ectoderm.
abstract: Pitx3 is expressed in tissues fated to contribute to eye development, namely, neurula stage ectoderm and pre-chordal mesoderm, then presumptive lens ectoderm, placode, and finally lens. Pitx3 overexpression alters lens, optic cup, optic nerve, and diencephalon development. Many of the induced anomalies are attributable to midline deficits; however, as assessed by molecular markers, ectopic Pitx3 appears to temporarily enlarge the lens field. These changes are usually insufficient to generate either ectopic lenses to enlarge the eye that eventually differentiates. Conversely, use of a repressor chimera or of antisense morpholinos alters early expression of marker genes, and later inhibits lens development, thereby abrogating retinal induction. Reciprocal grafting experiments using wild-type and morpholino-treated tissues demonstrate that Pitx3 expression in the presumptive lens ectoderm is required for lens formation. Contradictory to recent assertions that retina can form in the absence of a lens, the expression of Pitx3 in the presumptive lens ectoderm is critical for retina development.
authors.affiliation: Biological Sciences, University of Windsor, Windsor, Ontario, Canada.
authors.forename: Farhad
authors.initials: F
authors.lastname: Khosrowshahian
authors.forename: Marian
authors.initials: M
authors.lastname: Wolanski
authors.forename: Wing Y
authors.initials: WY
authors.lastname: Chang
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Fujiki
authors.forename: Larry
authors.initials: L
authors.lastname: Jacobs
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Crawford
mesh_terms: D000818:Animals; D015415:Biomarkers; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004475:Ectoderm / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007908:Lens, Crystalline / Q000196:embryology* / Q000378:metabolism*; D012160:Retina / Q000196:embryology* / Q000378:metabolism*; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism
chemical_list: D015415:Biomarkers; D018076:DNA, Complementary; C506549:Pitx3 protein, Xenopus; D014157:Transcription Factors; D029867:Xenopus Proteins