The Experts below are selected from a list of 89604 Experts worldwide ranked by ideXlab platform
Milan Jamrich - One of the best experts on this subject based on the ideXlab platform.
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Regulation of vertebrate Eye Development by Rx genes
The International Journal of Developmental Biology, 2004Co-Authors: Travis J Bailey, Heithem M. El-hodiri, Li Zhang, Rina Shah, Peter H. Mathers, Milan JamrichAbstract:The paired-like homeobox-containing gene Rx has a critical role in the Eye Development of several vertebrate species including Xenopus, mouse, chicken, medaka, zebrafish and human. Rx is initially expressed in the anterior neural region of developing embryos, and later in the retina and ventral hypothalamus. Abnormal regulation or function of Rx results in severe abnormalities of Eye formation. Overexpression of Rx in Xenopus and zebrafish embryos leads to overproliferation of retinal cells. A targeted elimination of Rx in mice results in a lack of Eye formation. Mutations in Rx genes are the cause of the mouse mutation Eyeless (ey1), the medaka temperature sensitive mutation Eyeless (el) and the zebrafish mutation chokh. In humans, mutations in Rx lead to anophthalmia. All of these studies indicate that Rx genes are key factors in vertebrate Eye formation. Because these results cannot be easily reconciled with the most popular dogmas of the field, we offer our interpretation of Eye Development and evolution.
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the rx homeobox gene is essential for vertebrate Eye Development
Nature, 1997Co-Authors: Peter H. Mathers, Alexander Grinberg, K A Mahon, Milan JamrichAbstract:Development of the vertebrate Eye requires a series of steps including specification of the anterior neural plate, evagination of the optic vesicles from the ventral forebrain, and the cellular differentiation of the lens and retina. Homeobox-containing genes, especially the transcription regulator Pax6, play a critical role in vertebrate and invertebrate Eye formation. Mutations in Pax6 function result in Eye malformations known as Aniridia in humans and Small Eye syndrome in mice1,2,3. The Drosophila homologue of Pax6, Eyeless, is also necessary for correct invertebrate Eye Development, and its misexpression leads to formation of ectopic Eyes in Drosophila4,5. Here we show that a conserved vertebrate homeobox gene, Rx, is essential for normal Eye Development, and that its misexpression has profound effects on Eye morphology. Xenopus embryos injected with synthetic Rx RNA develop ectopic retinal tissue and display hyperproliferation in the neuroretina. Mouse embryos carrying a null allele of this gene do not form optic cups and so do not develop Eyes. The Rx gene family plays an important role in the establishment and/or proliferation of retinal progenitor cells.
Emmanuelle Havis - One of the best experts on this subject based on the ideXlab platform.
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Unliganded thyroid hormone receptor is essential for Xenopus laevis Eye Development
The EMBO journal, 2006Co-Authors: Emmanuelle Havis, Sébastien Le Mével, Ghislaine Morvan Dubois, De Li Shi, Thomas S. Scanlan, Barbara A. Demeneix, Laurent M. SachsAbstract:Thyroid hormone receptors generally activate transcription of target genes in the presence of thyroid hormone (T3) and repress their transcription in its absence. Here, we investigated the role of unliganded thyroid hormone receptor (TR) during vertebrate Development using an amphibian model. Previous studies led to the hypothesis that before production of endogenous T3, the presence of unliganded receptor is essential for premetamorphic tadpole growth. To test this hypothesis, we generated a Xenopus laevis TR β mutant construct ineffective for gene repression owing to impaired corepressor NCoR recruitment. Overexpression by germinal transgenesis of the mutant receptor leads to lethality during early Development with numerous defects in cranio-facial and Eye Development. These effects correlate with TR expression profiles at these early stages. Molecular analysis of transgenic mutants reveals perturbed expression of genes involved in Eye Development. Finally, treatment with iopanoic acid or NH-3, modulators of thyroid hormone action, leads to abnormal Eye Development. In conclusion, the data reveal a role of unliganded TR in Eye Development.
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Unliganded thyroid hormone receptor is essential for Xenopus laevis Eye Development.
EMBO Journal, 2006Co-Authors: Emmanuelle Havis, Le Mevel S, G. Morvan-duboisAbstract:Thyroid hormone receptors generally activate transcription of target genes in the presence of thyroid hormone (T(3)) and repress their transcription in its absence. Here, we investigated the role of unliganded thyroid hormone receptor (TR) during vertebrate Development using an amphibian model. Previous studies led to the hypothesis that before production of endogenous T(3), the presence of unliganded receptor is essential for premetamorphic tadpole growth. To test this hypothesis, we generated a Xenopus laevis TR beta mutant construct ineffective for gene repression owing to impaired corepressor NCoR recruitment. Overexpression by germinal transgenesis of the mutant receptor leads to lethality during early Development with numerous defects in cranio-facial and Eye Development. These effects correlate with TR expression profiles at these early stages. Molecular analysis of transgenic mutants reveals perturbed expression of genes involved in Eye Development. Finally, treatment with iopanoic acid or NH-3, modulators of thyroid hormone action, leads to abnormal Eye Development. In conclusion, the data reveal a role of unliganded TR in Eye Development.
Peter H. Mathers - One of the best experts on this subject based on the ideXlab platform.
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Regulation of vertebrate Eye Development by Rx genes
The International Journal of Developmental Biology, 2004Co-Authors: Travis J Bailey, Heithem M. El-hodiri, Li Zhang, Rina Shah, Peter H. Mathers, Milan JamrichAbstract:The paired-like homeobox-containing gene Rx has a critical role in the Eye Development of several vertebrate species including Xenopus, mouse, chicken, medaka, zebrafish and human. Rx is initially expressed in the anterior neural region of developing embryos, and later in the retina and ventral hypothalamus. Abnormal regulation or function of Rx results in severe abnormalities of Eye formation. Overexpression of Rx in Xenopus and zebrafish embryos leads to overproliferation of retinal cells. A targeted elimination of Rx in mice results in a lack of Eye formation. Mutations in Rx genes are the cause of the mouse mutation Eyeless (ey1), the medaka temperature sensitive mutation Eyeless (el) and the zebrafish mutation chokh. In humans, mutations in Rx lead to anophthalmia. All of these studies indicate that Rx genes are key factors in vertebrate Eye formation. Because these results cannot be easily reconciled with the most popular dogmas of the field, we offer our interpretation of Eye Development and evolution.
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the rx homeobox gene is essential for vertebrate Eye Development
Nature, 1997Co-Authors: Peter H. Mathers, Alexander Grinberg, K A Mahon, Milan JamrichAbstract:Development of the vertebrate Eye requires a series of steps including specification of the anterior neural plate, evagination of the optic vesicles from the ventral forebrain, and the cellular differentiation of the lens and retina. Homeobox-containing genes, especially the transcription regulator Pax6, play a critical role in vertebrate and invertebrate Eye formation. Mutations in Pax6 function result in Eye malformations known as Aniridia in humans and Small Eye syndrome in mice1,2,3. The Drosophila homologue of Pax6, Eyeless, is also necessary for correct invertebrate Eye Development, and its misexpression leads to formation of ectopic Eyes in Drosophila4,5. Here we show that a conserved vertebrate homeobox gene, Rx, is essential for normal Eye Development, and that its misexpression has profound effects on Eye morphology. Xenopus embryos injected with synthetic Rx RNA develop ectopic retinal tissue and display hyperproliferation in the neuroretina. Mouse embryos carrying a null allele of this gene do not form optic cups and so do not develop Eyes. The Rx gene family plays an important role in the establishment and/or proliferation of retinal progenitor cells.
G. Morvan-dubois - One of the best experts on this subject based on the ideXlab platform.
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Unliganded thyroid hormone receptor is essential for Xenopus laevis Eye Development.
EMBO Journal, 2006Co-Authors: Emmanuelle Havis, Le Mevel S, G. Morvan-duboisAbstract:Thyroid hormone receptors generally activate transcription of target genes in the presence of thyroid hormone (T(3)) and repress their transcription in its absence. Here, we investigated the role of unliganded thyroid hormone receptor (TR) during vertebrate Development using an amphibian model. Previous studies led to the hypothesis that before production of endogenous T(3), the presence of unliganded receptor is essential for premetamorphic tadpole growth. To test this hypothesis, we generated a Xenopus laevis TR beta mutant construct ineffective for gene repression owing to impaired corepressor NCoR recruitment. Overexpression by germinal transgenesis of the mutant receptor leads to lethality during early Development with numerous defects in cranio-facial and Eye Development. These effects correlate with TR expression profiles at these early stages. Molecular analysis of transgenic mutants reveals perturbed expression of genes involved in Eye Development. Finally, treatment with iopanoic acid or NH-3, modulators of thyroid hormone action, leads to abnormal Eye Development. In conclusion, the data reveal a role of unliganded TR in Eye Development.
Laurent M. Sachs - One of the best experts on this subject based on the ideXlab platform.
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Unliganded thyroid hormone receptor is essential for Xenopus laevis Eye Development
The EMBO journal, 2006Co-Authors: Emmanuelle Havis, Sébastien Le Mével, Ghislaine Morvan Dubois, De Li Shi, Thomas S. Scanlan, Barbara A. Demeneix, Laurent M. SachsAbstract:Thyroid hormone receptors generally activate transcription of target genes in the presence of thyroid hormone (T3) and repress their transcription in its absence. Here, we investigated the role of unliganded thyroid hormone receptor (TR) during vertebrate Development using an amphibian model. Previous studies led to the hypothesis that before production of endogenous T3, the presence of unliganded receptor is essential for premetamorphic tadpole growth. To test this hypothesis, we generated a Xenopus laevis TR β mutant construct ineffective for gene repression owing to impaired corepressor NCoR recruitment. Overexpression by germinal transgenesis of the mutant receptor leads to lethality during early Development with numerous defects in cranio-facial and Eye Development. These effects correlate with TR expression profiles at these early stages. Molecular analysis of transgenic mutants reveals perturbed expression of genes involved in Eye Development. Finally, treatment with iopanoic acid or NH-3, modulators of thyroid hormone action, leads to abnormal Eye Development. In conclusion, the data reveal a role of unliganded TR in Eye Development.
