On the synaptogenic sequence in the chick retina

Hughes, William F.; LaVelle, Arthur

doi:10.1002/ar.1091790302

Cited by 137 publications

(82 citation statements)

References 9 publications

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“…Photoreceptors do not differentiate morphologically until E9.5, when the inner segments appear (Meller and Tetzlaff, 1976). The outer segments appear on E13 (Meller and Tetzlaff, 1976), and the synapses from photoreceptors to bipolar cells are evident on about E18 (Hughes and LaVelle, 1974). As discussed above, we found that RaxL is expressed in developing photoreceptors, but not in mature photoreceptors on E19, suggesting that RaxL is not required for the maintenance or survival of mature photoreceptors.…”

Section: The Expression Pattern Of Raxl Suggests a Role In Early Devesupporting

confidence: 61%

The chickenRaxLgene plays a role in the initiation of photoreceptor differentiation

2002

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The paired type homeodomain gene, Rax, was previously identified as a key molecule in early eye formation in mice and humans. We report the expression patterns of two Rax family members from chicken, Rax and RaxL, and on the function of RaxL in photoreceptor development. Both Rax and RaxL are expressed in early retinal progenitor cells, with Rax being expressed at a significantly higher level than RaxL. At the time that photoreceptors begin to form, RaxL appears at a relatively high level in a subset of cells within the zone of proliferating progenitor cells. Subsequently, it is expressed in cells migrating to the photoreceptor layer, where it is highly expressed during the initial, but not late, stages of photoreceptor differentiation. To test the function of RaxL, a putative dominant-negative allele of RaxL comprising a fusion of the engrailed repressor domain and a region of RaxL (EnRaxL∆C) was introduced in vivo into the early chick eye using a retroviral vector. EnRaxL∆C, but not the dominant negative Rax (EnRax∆C), caused a significant reduction in expression of early markers of photoreceptor cells. Examination of the transactivation activity of RaxL on a reporter construct bearing a canonical photoreceptor-specific enhancer element showed that RaxL exhibited significant activation activity, and that this activity was severely diminished in the presence of EnRaxL∆C. The effect on photoreceptor gene expression in vivo was specific in that other cell types were unaffected, as was general proliferation in the retina. The reduction in numbers of cells expressing photoreceptor markers was probably due to decreased survival of developing photoreceptor cells, as there was increased apoptosis among cells of the retina expressing dominant-negative RaxL. We propose that RaxL plays a role in the initiation of differentiation, and also possibly commitment, of photoreceptor cells in the chicken retina.

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Section: The Expression Pattern Of Raxl Suggests a Role In Early Devesupporting

confidence: 61%

The chickenRaxLgene plays a role in the initiation of photoreceptor differentiation

2002

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“…Thus, during development, in chick retina two arginine-requiring pathways appear to exist and these seem to be involved in differentiation processes and synaptogenesis. Interestingly, in chick embryo retina synapses have not been detected prior to the 13th embryonic day [19].…”

Section: Discussionmentioning

confidence: 97%

Nitric oxide synthase in chick embryo retina during development

et al. 1996

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High levels of nitric oxide synthase were found in the early stages of developing chick embryo retina. The enzyme activity sharply decreased up to 13-day-old chick embryo retina, when the level of the last embryonic day was reached. The results show that nitric oxide is synthesized in chick embryo retina prior to synaptogenesis. The incubation of chick embryo retinas in presence of NMDA increased the synthesis of nitric oxide, thus, the appearance of nitric oxide production before the synaptogenesis in the retina as well as in the brain may be considered as signal for the development and shaping of neuronal and non-neuronal cells.

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“…As the retinal pigment epithelium (RPE) becomes tightly associated with the neural retina and hampers fluorescence observations in post-hatched chicks, we carried out our analysis at E16 and earlier, the stages during which we could still separate the RPE from the associating neural retinas. Although E16 is still an embryonic stage, synaptic ribbons and vesicles are already present in the outer plexiform layer (Hughes and LaVelle, 1974), suggesting that basic neural connecting patterns are already established.…”

Section: Embryonic Chicken Retinas Have 3 Morphologically Distinct Sumentioning

confidence: 99%

Cadherin is required for dendritic morphogenesis and synaptic terminal organization of retinal horizontal cells

et al. 2006

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Dendrite morphology of neurons provides a structural basis for their physiological characteristics, and is precisely regulated in a cell type-dependent manner. Using a unique transposon-mediated gene transfer system that enables conditional and cell-type specific expression of exogenous genes, we investigated the role of cadherin on dendritic morphogenesis of horizontal cells in the developing chicken retina. We first visualized single horizontal cells by overexpressing membrane-targeted EGFP, and confirmed that there were three subtypes of horizontal cells, the dendritic terminals of which projected to distinct synaptic sites in the outer plexiform layer. Expression of a dominant-negative cadherin decreased the dendritic field size, and perturbed the termination of dendritic processes onto the photoreceptor cells. The cadherin blockade also impaired the accumulation of GluR4, a postsynaptic marker, at the cone pedicles. We thus provide in vivo evidence that cadherin is required for dendrite morphogenesis of horizontal cells and subsequent synapse formation with photoreceptor cells in the vertebrate retina.

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On the synaptogenic sequence in the chick retina

Cited by 137 publications

References 9 publications

The chickenRaxLgene plays a role in the initiation of photoreceptor differentiation

The chickenRaxLgene plays a role in the initiation of photoreceptor differentiation

Nitric oxide synthase in chick embryo retina during development

Cadherin is required for dendritic morphogenesis and synaptic terminal organization of retinal horizontal cells

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