Abstract
Fibroblast growth factor-8 (FGF-8) is an important signaling molecule in the generation and patterning of the midbrain, tooth, and limb. In this study we show that it is also involved in eye development. In the chick, Fgf-8 transcripts first appear in the distal optic vesicle when it contacts the head ectoderm. Subsequently Fgf-8 expression increases and becomes localized to the central area of the presumptive neural retina (NR) only. Application of FGF-8 has two main effects on the eye. First, it converts presumptive retinal pigment epithelium (RPE) into NR. This is apparent by the failure to express Bmp-7 and Mitf (a marker gene for the RPE) in the outer layer of the optic cup, coupled with the induction of NR genes, such as Rx, Sgx-1 and Fgf-8 itself. The induced retina displays the typical multilayered cytoarchitecture and expresses late neuronal differentiation markers such as synaptotagmin and islet-1. The second effect of FGF-8 exposure is the induction of both lens formation and lens fiber differentiation. This is apparent by the expression of a lens specific marker, L-Maf, and by morphological changes of lens cells. These results suggest that FGF-8 plays a role in the initiation and differentiation of neural retina and lens.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Avian Proteins*
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Bone Morphogenetic Protein 7
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Bone Morphogenetic Proteins / genetics
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Bone Morphogenetic Proteins / metabolism
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Cell Differentiation / genetics
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Chick Embryo
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Embryonic Induction / genetics
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Eye / embryology*
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Eye Proteins*
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Fibroblast Growth Factor 8
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Fibroblast Growth Factors / genetics*
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Fibroblast Growth Factors / metabolism*
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Gene Expression Regulation, Developmental
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Homeodomain Proteins / genetics
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LIM-Homeodomain Proteins
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Lens, Crystalline / embryology
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Maf Transcription Factors
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Mesoderm
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Microphthalmia-Associated Transcription Factor
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Nerve Tissue Proteins / genetics
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PAX6 Transcription Factor
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Paired Box Transcription Factors
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Pigment Epithelium of Eye / embryology
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Repressor Proteins
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Retina / embryology
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Transcription Factors / metabolism
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Transforming Growth Factor beta*
Substances
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Avian Proteins
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Bone Morphogenetic Protein 7
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Bone Morphogenetic Proteins
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DNA-Binding Proteins
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Eye Proteins
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Homeodomain Proteins
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L-MAF protein, Gallus gallus
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LIM-Homeodomain Proteins
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Maf Transcription Factors
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Microphthalmia-Associated Transcription Factor
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Nerve Tissue Proteins
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PAX6 Transcription Factor
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Paired Box Transcription Factors
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Repressor Proteins
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Rx protein, vertebrate
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SOHO-1 protein, Gallus gallus
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Transcription Factors
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Transforming Growth Factor beta
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insulin gene enhancer binding protein Isl-1
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Fibroblast Growth Factor 8
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Fibroblast Growth Factors