The Rx-like Homeobox Gene (Rx-L) Is Necessary for Normal Photoreceptor Development

Pan, Yi; Nekkalapudi, Srivamsi; Kelly, Lisa E.; El‐Hodiri, Heithem M.

doi:10.1167/iovs.06-0167

Cited by 25 publications

(52 citation statements)

References 44 publications

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“…One may speculate, what is the reason for keeping the expression of Rx in differentiated ciliary photoreceptors in distantly related species. Analogous to the Otx scenario, the direct regulation of vertebrate c-opsins by Rx (Kimura et al 2000;Wang et al 2004;Pan et al 2006) may point to an ancestral condition of ciliary photoreceptor cell type. In these cells, the regulation of c-opsins by Rx might have been already established and, being a differentiation subcircuit, it was conserved throughout evolution.…”

Section: Redeployment Of a Selected Set Of Transcription Factors For mentioning

confidence: 99%

Eye evolution: common use and independent recruitment of genetic components

Vopálenský

Kozmík

2009

Phil. Trans. R. Soc. B

104

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Animal eyes can vary in complexity ranging from a single photoreceptor cell shaded by a pigment cell to elaborate arrays of these basic units, which allow image formation in compound eyes of insects or camera-type eyes of vertebrates. The evolution of the eye requires involvement of several distinct components-photoreceptors, screening pigment and genes orchestrating their proper temporal and spatial organization. Analysis of particular genetic and biochemical components shows that many evolutionary processes have participated in eye evolution. Multiple examples of co-option of crystallins, Ga protein subunits and screening pigments contrast with the conserved role of opsins and a set of transcription factors governing eye development in distantly related animal phyla. The direct regulation of essential photoreceptor genes by these factors suggests that this regulatory relationship might have been already established in the ancestral photoreceptor cell.

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Section: Redeployment Of a Selected Set Of Transcription Factors For mentioning

confidence: 99%

Eye evolution: common use and independent recruitment of genetic components

Vopálenský

Kozmík

2009

Phil. Trans. R. Soc. B

104

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“…Nr2e3cds/ pBlueScript was then linearized with EcoRI (New England Biolabs) and the antisense riboprobe made using T7 RNA polymerase plus (Ambion). Antisense riboprobes for Rhodopsin, Tlx, Rx were generated as described previously (Hollemann et al, 1998, Mathers et al, 1997, Pan et al, 2006.…”

Section: In Situ Hybridizationmentioning

confidence: 99%

The Xenopus ortholog of the nuclear hormone receptor Nr2e3 is primarily expressed in developing photoreceptors

Luna¹,

El‐Hodiri²

2007

Int. J. Dev. Biol.

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Nr2e3 is a nuclear hormone receptor that is involved in rod photoreceptor differentiation. The Nr2e3 gene was previously identified in humans, mice, zebrafish and chicken. In all species, Nr2e3 expression is restricted to the retina and is believed to have a role in rod photoreceptor specification and maintenance. Here we report the identification and characterization of the Xenopus Nr2e3. We found that Nr2e3 is primarily expressed in developing rod photoreceptors. In contrast to other species, Nr2e3 is also expressed in the notochord and pineal gland during Xenopus laevis development.

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“…In Xenopus laevis, two Rax genes (xRx and xRx-L/xRx2) have been identified (7,21), and in zebra fish, three Rax genes (zRx1 to zRx3) have been isolated (7). Interestingly, the expression pattern of zebra fish Rx3 showed more similarity to that of frog and mouse Rax genes than to that of the zebra fish Rx1 and Rx2 genes (23).…”

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confidence: 99%

“…Rax overexpression promotes the proliferation of RPCs in frogs and zebra fish (7,(10)(11)(12)(13). In addition to the function in RPCs, Rax plays significant roles in the development of photoreceptor cells and Müller glial cells (14)(15)(16)(17)(18)(19).Rax paralog genes have been identified in various vertebrate species (20)(21)(22). In Xenopus laevis, two Rax genes (xRx and xRx-L/xRx2) have been identified (7, 21), and in zebra fish, three Rax genes (zRx1 to zRx3) have been isolated (7).…”

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confidence: 99%

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Rax Homeoprotein Regulates Photoreceptor Cell Maturation and Survival in Association with Crx in the Postnatal Mouse Retina

Irie

Sanuki

Muranishi

et al. 2015

Molecular and Cellular Biology

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A number of homeodomain transcription factors, which play significant roles in retinal development, have been identified in vertebrates (1-4). Rax is a homeodomain transcription factor that is essential for various processes in vertebrate retinal development (5). The Rax gene was first identified as a paired-type homeobox gene expressed in the optic vesicle and the presumptive diencephalon area in the early mouse embryo (6, 7). Rax is evolutionarily well conserved from Drosophila melanogaster to humans. Rax is highly expressed in retinal progenitor cells (RPCs), and its expression in the retina gradually decreases as RPCs become postmitotic and begin to differentiate. Rax-null mutant mice exhibit a reduction of brain size and an absence of the optic vesicle (5, 7). Mutations in human RAX are associated with anophthalmia and microphthalmia (8, 9). Rax overexpression promotes the proliferation of RPCs in frogs and zebra fish (7,(10)(11)(12)(13). In addition to the function in RPCs, Rax plays significant roles in the development of photoreceptor cells and Müller glial cells (14)(15)(16)(17)(18)(19).Rax paralog genes have been identified in various vertebrate species (20)(21)(22). In Xenopus laevis, two Rax genes (xRx and xRx-L/xRx2) have been identified (7, 21), and in zebra fish, three Rax genes (zRx1 to zRx3) have been isolated (7). Interestingly, the expression pattern of zebra fish Rx3 showed more similarity to that of frog and mouse Rax genes than to that of the zebra fish Rx1 and Rx2 genes (23). In chicks, two Rax genes (cRax and cRaxL/ cRax2) have been identified (20). The chick Rax2 gene is expressed in both retinal progenitor cells and early-developing photoreceptors, while chick Rax is predominantly expressed in retinal progenitor cells. It was also reported that chick Rax2 is implicated in cone photoreceptor differentiation and that the expression of a putative dominant negative allele of a chick Rax2 gene caused a significant reduction in the level of expression of cone photoreceptor genes (20). Human RAX2/QRX, which is expressed in the outer nuclear layer (ONL) and inner nuclear layer (INL) of the adult human retina, was identified to be a PCE-1-binding protein by acting synergistically with CRX and NRL to modulate the expression of photoreceptor genes. Monkey, cow, and dog genomes also contain two Rax genes. On the other hand, the Rax2 gene is absent from mouse and rat genomes (22). This raises the question of whether mouse Rax plays an essential role in photoreceptor development during postnatal stages like human Rax2 does.In the current study, we investigated a functional role for Rax in postnatal mouse retinas, which contain a single Rax gene. We report that mouse Rax modulates the expression of photoreceptor genes in the postnatal retina by interacting with Crx. Conditional ablation of Rax in postnatal photoreceptors led to a significant decrease in the level of expression of rod and cone genes and to cone photoreceptor cell death, suggesting that Rax is essential for the maturation of rods and co...

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The Rx-like Homeobox Gene (Rx-L) Is Necessary for Normal Photoreceptor Development

Abstract: The results suggest that Rx-L functions to regulate rod and cone development by activating photoreceptor-specific gene expression.

Cited by 25 publications

References 44 publications

Eye evolution: common use and independent recruitment of genetic components

Eye evolution: common use and independent recruitment of genetic components

The Xenopus ortholog of the nuclear hormone receptor Nr2e3 is primarily expressed in developing photoreceptors

Rax Homeoprotein Regulates Photoreceptor Cell Maturation and Survival in Association with Crx in the Postnatal Mouse Retina

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