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Published on: April 5, 2021
Regulation of vertebrate eye development by Rx genes
Travis J Bailey1, Heithem El-Hodiri, Li Zhang
1Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA.
Abstract:
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.
Insights
The paired-like homeobox-containing gene Rx is crucial for vertebrate eye development, regulating retinal and hypothalamic formation. Its disruption causes severe eye abnormalities, including anophthalmia, highlighting its essential role.
Area of Science:
- Developmental biology
- Genetics
- Evolutionary biology
Background:
- The paired-like homeobox-containing gene Rx plays a vital role in vertebrate eye development.
- Rx is expressed in the anterior neural region, retina, and ventral hypothalamus during embryonic development.
Purpose of the Study:
- To investigate the critical role of the Rx gene in vertebrate eye formation.
- To reconcile experimental findings with existing theories on eye development and evolution.
Main Methods:
- Analysis of Rx gene expression patterns in developing embryos.
- Studying the effects of Rx gene manipulation (overexpression and elimination) in various vertebrate models.
- Examining mutations in Rx genes associated with eye abnormalities.
Main Results:
- Rx gene is essential for eye formation across species like Xenopus, mouse, and human.
- Overexpression of Rx leads to retinal cell overproliferation.
- Targeted elimination of Rx in mice results in a complete lack of eye formation.
- Mutations in Rx are linked to conditions like anophthalmia and specific mutations (eyeless, chokh).
Conclusions:
- Rx genes are fundamental factors in vertebrate eye development.
- The findings challenge current dogmas, prompting a re-evaluation of eye development and evolution.
- Rx's function is conserved across diverse vertebrate species, underscoring its evolutionary significance.
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