The Xenopus homologue of the Drosophila gene tailless has a function in early eye development

Development ◽  
1998 ◽  
Vol 125 (13) ◽  
pp. 2425-2432 ◽  
Author(s):  
T. Hollemann ◽  
E. Bellefroid ◽  
T. Pieler
Keyword(s):  
Eye Development ◽  
Neural Plate ◽  
Regulatory Function ◽  
Genetic Circuits ◽  
Optic Stalk ◽  
Drosophila Gene ◽  
Ciliary Margin ◽  
Evolutionarily Conserved ◽  
Optic Cup ◽  
Vertebrate Eye

Genetic circuits responsible for the development of photoreceptive organs appear to be evolutionarily conserved. Here, the Xenopus homologue Xtll of the Drosophila gene tailless (tll), which we find to be expressed during early eye development, is characterized with respect to its relationship to vertebrate regulators of eye morphogenesis, such as Pax6 and Rx. Expression of all three genes is first detected in the area corresponding to the eye anlagen within the open neural plate in partially overlapping, but not identical, patterns. During the evagination of the optic vesicle, Xtll expression is most prominent in the optic stalk, as well as in the distal tip of the forming vesicle. In tadpole-stage embryos, Xtll gene transcription is most prominent in the ciliary margin of the optic cup. Inhibition of Xtll function in Xenopus embryos interferes specifically with the evagination of the eye vesicle and, in consequence, Xpax6 gene expression is severely reduced in such manipulated embryos. These findings suggest that Xtll serves an important regulatory function in the earliest phases of vertebrate eye development.

Patterning the Vertebrate Retina with Morphogenetic Signaling Pathways

2019 ◽  
Vol 26 (2) ◽  
pp. 185-196 ◽  
Author(s):  
Marcos J. Cardozo ◽  
María Almuedo-Castillo ◽  
Paola Bovolenta
Keyword(s):  
Signaling Pathways ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Subsequent Development ◽  
Neural Retina ◽  
Bmp Signaling ◽  
Vertebrate Species ◽  
Optic Stalk ◽  
Optic Cup ◽  
Vertebrate Eye

The primordium of the vertebrate eye is composed of a pseudostratified and apparently homogeneous neuroepithelium, which folds inward to generate a bilayered optic cup. During these early morphogenetic events, the optic vesicle is patterned along three different axes—proximo-distal, dorso-ventral, and naso-temporal—and three major domains: the neural retina, the retinal pigment epithelium (RPE), and the optic stalk. These fundamental steps that enable the subsequent development of a functional eye, entail the precise coordination among genetic programs. These programs are driven by the interplay of signaling pathways and transcription factors, which progressively dictate how each tissue should evolve. Here, we discuss the contribution of the Hh, Wnt, FGF, and BMP signaling pathways to the early patterning of the retina. Comparative studies in different vertebrate species have shown that their morphogenetic activity is repetitively used to orchestrate the progressive specification of the eye with evolutionary conserved mechanisms that have been adapted to match the specific need of a given species.

scholarly journals Eye morphogenesis driven by epithelial flow into the optic cup facilitated by modulation of bone morphogenetic protein

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Stephan Heermann ◽  
Lucas Schütz ◽  
Steffen Lemke ◽  
Kerstin Krieglstein ◽  
Joachim Wittbrodt
Keyword(s):  
Marginal Zone ◽  
Eye Development ◽  
Optic Vesicle ◽  
Basal Surface ◽  
Morphogenetic Protein ◽  
Retinal Determination ◽  
Optic Cup ◽  
Morphological Transformations ◽  
Vertebrate Eye ◽  
Ciliary Marginal Zone

The hemispheric, bi-layered optic cup forms from an oval optic vesicle during early vertebrate eye development through major morphological transformations. The overall basal surface, facing the developing lens, is increasing, while, at the same time, the space basally occupied by individual cells is decreasing. This cannot be explained by the classical view of eye development. Using zebrafish (Danio rerio) as a model, we show that the lens-averted epithelium functions as a reservoir that contributes to the growing neuroretina through epithelial flow around the distal rims of the optic cup. We propose that this flow couples morphogenesis and retinal determination. Our 4D data indicate that future stem cells flow from their origin in the lens-averted domain of the optic vesicle to their destination in the ciliary marginal zone. BMP-mediated inhibition of the flow results in ectopic neuroretina in the RPE domain. Ultimately the ventral fissure fails to close resulting in coloboma.

scholarly journals Phase transition specified by a binary code patterns the vertebrate eye cup

2021 ◽  
Author(s):  
Revathi Balasubramanian ◽  
Xuanyu Min ◽  
Peter M.J. Quinn ◽  
Quentin Lo Giudice ◽  
Chenqi Tao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Wnt Signaling ◽  
Single Cell Analysis ◽  
Fgf Signaling ◽  
Independent Manner ◽  
Ciliary Margin ◽  
Evolutionarily Conserved ◽  
Human Ips Cells ◽  
Vertebrate Eye

The developing vertebrate eye cup is partitioned into the neural retina (NR), the retinal pigmented epithelium (RPE) and the ciliary margin (CM). By single cell analysis, we showed that a gradient of FGF signaling regulates demarcation and subdivision of the CM and controls its stem cell-like property of self-renewal, differentiation and survival. This regulation by FGF is balanced by an evolutionarily conserved Wnt signaling gradient induced by the lens ectoderm and the periocular mesenchyme, which specifies the CM and the distal RPE. These two morphogen gradients converge in the CM where FGF signaling promotes Wnt signaling by stabilizing β-catenin in a GSK3β-independent manner. We further showed that activation of Wnt signaling converts the NR to either the CM or the RPE depending on the level of FGF signaling. Conversely, activation of FGF transforms the RPE to the NR or CM dependent on Wnt activity. We demonstrated that the default fate of the eye cup is the NR, but synergistic FGF and Wnt signaling promotes CM formation both in vivo and in retinal organoid culture of human iPS cells. Our study reveals that the vertebrate eye develops through phase transition determined by a combinatorial code of FGF and Wnt signaling.

scholarly journals Build me up optic cup: Intrinsic and extrinsic mechanisms of vertebrate eye morphogenesis

2021 ◽  
Vol 476 ◽  
pp. 128-136
Author(s):  
Macaulie A. Casey ◽  
Sarah Lusk ◽  
Kristen M. Kwan
Keyword(s):  
Optic Cup ◽  
Vertebrate Eye ◽  
Eye Morphogenesis

Secreted inducers in vertebrate eye development: more functions for old morphogens

2006 ◽  
Vol 16 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Pilar Esteve ◽  
Paola Bovolenta
Keyword(s):  
Eye Development ◽  
Vertebrate Eye

scholarly journals AP-2α knockout mice exhibit optic cup patterning defects and failure of optic stalk morphogenesis

2010 ◽  
Vol 19 (9) ◽  
pp. 1791-1804 ◽  
Author(s):  
Erin A. Bassett ◽  
Trevor Williams ◽  
Amanda L. Zacharias ◽  
Philip J. Gage ◽  
Sabine Fuhrmann ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Optic Stalk ◽  
Optic Cup

Identification of an evolutionarily conserved 110 base-pair cis-acting regulatory sequence that governs Wnt-1 expression in the murine neural plate

Development ◽  
1998 ◽  
Vol 125 (14) ◽  
pp. 2735-2746 ◽  
Author(s):  
D.H. Rowitch ◽  
Y. Echelard ◽  
P.S. Danielian ◽  
K. Gellner ◽  
S. Brenner ◽  
...  
Keyword(s):  
Base Pair ◽  
Regulatory Element ◽  
Regulatory Region ◽  
Neural Plate ◽  
Homologous Region ◽  
Regulatory Sequence ◽  
Embryonic Mouse ◽  
Cis Acting ◽  
Evolutionarily Conserved

The generation of anterior-posterior polarity in the vertebrate brain requires the establishment of regional domains of gene expression at early somite stages. Wnt-1 encodes a signal that is expressed in the developing midbrain and is essential for midbrain and anterior hindbrain development. Previous work identified a 5.5 kilobase region located downstream of the Wnt-1 coding sequence which is necessary and sufficient for Wnt-1 expression in vivo. Using a transgenic mouse reporter assay, we have now identified a 110 base pair regulatory sequence within the 5.5 kilobase enhancer, which is sufficient for expression of a lacZ reporter in the approximate Wnt-1 pattern at neural plate stages. Multimers of this element driving Wnt-1 expression can partially rescue the midbrain-hindbrain phenotype of Wnt-1(−/−) embryos. The possibility that this region represents an evolutionarily conserved regulatory module is suggested by the identification of a highly homologous region located downstream of the wnt-1 gene in the pufferfish (Fugu rubripes). These sequences are capable of appropriate temporal and spatial activation of a reporter gene in the embryonic mouse midbrain; although, later aspects of the Wnt-1 expression pattern are absent. Genetic evidence has implicated Pax transcription factors in the regulation of Wnt-1. Although Pax-2 binds to the 110 base pair murine regulatory element in vitro, the location of the binding sites could not be precisely established and mutation of two putative low affinity sites did not abolish activation of a Wnt-1 reporter transgene in vivo. Thus, it is unlikely that Pax proteins regulate Wnt-1 by direct interactions with this cis-acting regulatory region. Our analysis of the 110 base pair minimal regulatory element suggests that Wnt-1 regulation is complex, involving different regulatory interactions for activation and the later maintenance of transgene expression in the dorsal midbrain and ventral diencephalon, and at the midbrain-hindbrain junction.

The Msh-like homeobox genes define domains in the developing vertebrate eye

Development ◽  
1991 ◽  
Vol 112 (4) ◽  
pp. 1053-1061 ◽  
Author(s):  
A.P. Monaghan ◽  
D.R. Davidson ◽  
C. Sime ◽  
E. Graham ◽  
R. Baldock ◽  
...  
Keyword(s):  
Mouse Embryo ◽  
Ciliary Body ◽  
Cellular Differentiation ◽  
Temporal Relationship ◽  
Chromosomal Location ◽  
Neural Retina ◽  
Optic Vesicle ◽  
Surface Ectoderm ◽  
Optic Cup ◽  
Vertebrate Eye

The mouse Hox-7.1 gene has previously been shown to be related to the Drosophila Msh homeobox-containing gene. Here we report the isolation of a new member of this family which resides at an unlinked chromosomal location and has been designated Hox-8.1. Both Hox-7.1 and Hox-8.1 are expressed in the mouse embryo during the early stages of eye development in a distinct spatial and temporal relationship. Hox-8.1 is expressed in the surface ectoderm and in the optic vesicle before invagination occurs in regions corresponding to the prospective corneal epithelium and neural retina, respectively. Hox-7.1 is expressed after formation of the optic cup, marking the domain that will give rise to the ciliary body. The activity of these genes indicates that the inner layer of the optic cup is differentiated into three distinct compartments before overt cellular differentiation occurs. Our results suggest that these genes are involved in defining the region that gives rise to the inner layer of the optic cup and in patterning this tissue to define the iris, ciliary body and retina.

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