A New Model for Olfactory Placode Development

Whitlock, Kathleen E.

doi:10.1159/000079742

Cited by 56 publications

(45 citation statements)

References 56 publications

(99 reference statements)

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“…In medaka, the differences in timing between the onset of expression of gnrh3 in the terminal nerve and gnrh1 in the hypothalamus led to the proposal that these populations do not share a common origin in the olfactory placode (Dubois et al, 2002;Parhar et al, 1998). Consistent with this hypothesis, we have found that, in zebrafish, GnRH3 cells of the terminal nerve have their origin in the cranial neural crest (Whitlock, 2004a;Whitlock, 2004b;Whitlock et al, 2003). Whether the terminal nerve arises from neural crest or the olfactory placode has been the subject of debate for the last century (Von Bartheld and Baker, 2004;Whitlock, 2004b).…”

Section: Neural Crest Origin For Gnrh3 Cells Of the Terminal Nervesupporting

confidence: 76%

A role forfoxd3andsox10in the differentiation of gonadotropin-releasing hormone (GnRH) cells in the zebrafishDanio rerio

et al. 2005

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Gonadotropin-releasing hormone (GnRH) is found in a wide range of vertebrate tissues, including the nervous system. In general, GnRH has two functions: endocrine, acting as a releasing hormone; and neuromodulatory,affecting neural activity in the peripheral and central nervous system. The best understood population of GnRH cells is that of the hypothalamus, which is essential for reproduction. Less well understood are the populations of GnRH cells found in the terminal nerve and midbrain, which appear to be neuromodulatory in function. The GnRH-containing cells of the midbrain are proposed to arise from the mesencephalic region of the neural tube. Previously, we showed that neuromodulatory GnRH cells of the terminal nerve arise from cranial neural crest. To test the hypothesis that neuromodulatory GnRH cells of the midbrain also arise from neural crest, we used gene knockdown experiments in zebrafish to disrupt neural crest development. We demonstrate that decrement of the function of foxd3 and/or sox10, two genes important for the development and specification of neural crest, resulted in a reduction and/or loss of GnRH cells of the midbrain, as well as a reduction in the number of terminal nerve GnRH cells. Therefore, our data support a neural crest origin for midbrain GnRH cells. Additionally, we demonstrate that knockdown of kallmann gene function resulted in the loss of endocrine GnRH cells of the hypothalamus, but not of neuromodulatory GnRH cells of the midbrain and terminal nerve, thus providing additional evidence for separate pathways controlling the development of neuromodulatory and endocrine GnRH cells.

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Section: Neural Crest Origin For Gnrh3 Cells Of the Terminal Nervesupporting

confidence: 76%

A role forfoxd3andsox10in the differentiation of gonadotropin-releasing hormone (GnRH) cells in the zebrafishDanio rerio

et al. 2005

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“…Role of Cxcl12a/Cxcr4b signaling in olfactory placode assembly Olfactory neuron precursors initially lie in the olfactory placodal field, the region stretching along the lateral edge of the anterior neural plate (Whitlock and Westerfield, 2000;Whitlock, 2004). As development progresses, they converge to form the olfactory placode.…”

Section: Discussionmentioning

confidence: 99%

Cxcl12/Cxcr4 chemokine signaling is required for placode assembly and sensory axon pathfinding in the zebrafish olfactory system

2007

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Positioning neurons in the right places and wiring axons to the appropriate targets are essential events for establishment of neural circuits. In the zebrafish olfactory system, precursors of olfactory sensory neurons (OSNs) assemble into a compact cluster to form the olfactory placode. Subsequently, OSNs differentiate and extend their axons to the presumptive olfactory bulb with high precision. In this study, we aim to elucidate the molecular mechanism underlying these two developmental processes. cxcr4b, encoding a chemokine receptor, is expressed in the migrating olfactory placodal precursors, and cxcl12a (SDF-1a), encoding a ligand for Cxcr4b, is expressed in the abutting anterior neural plate. The expression of cxcr4b persists in the olfactory placode at the initial phase of OSN axon pathfinding. At this time, cxcl12a is expressed along the placode-telencephalon border and at the anterior tip of the telencephalon, prefiguring the route and target of OSN axons, respectively. Interfering with Cxcl12a/Cxcr4b signaling perturbs the assembly of the olfactory placode, resulting in the appearance of ventrally displaced olfactory neurons. Moreover, OSN axons frequently fail to exit the olfactory placode and accumulate near the placode-telencephalon border in the absence of Cxcr4b-mediated signaling. These data indicate that chemokine signaling contributes to both the olfactory placode assembly and the OSN axon pathfinding in zebrafish.

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“…The diversity of cell lineages originating from the PPR cells may result from a relatively homogenous population of common progenitors, or from a number of smaller patches of cells that are biased towards a specific lineage depending on their location within the pre-placodal field Graham and Begbie, 2000;Streit, 2004;Whitlock, 2004). To address this issue, cell-fate mapping experiments examining position of cells during individual placode formation have been performed in chicken and zebrafish.…”

Section: Formation Of the Neural Tube Optic Vesicles And Lens Progenmentioning

confidence: 99%

Genetic and epigenetic mechanisms of gene regulation during lens development

Cvekl

Duncan

2007

Progress in Retinal and Eye Research

139

124

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Recent studies demonstrated a number of links between chromatin structure, gene expression, extracellular signaling and cellular differentiation during lens development. Lens progenitor cells originate from a pool of common progenitor cells, the pre-placodal region (PPR) which is formed due to a complex exchange of extracellular signals between the neural plate, naïve ectoderm and mesendoderm. A specific commitment to the lens program over alternate choices such as the formation of olfactory epithelium or the anterior pituitary is manifested by the formation of a thickened surface ectoderm, the lens placode. Mouse lens progenitor cells are characterized by the expression of a complement of lens lineage-specific transcription factors including Pax6, Six3 and Sox2, controlled by FGF and BMP signaling, followed later by c-Maf, Mab21like1, Prox1 and FoxE3. Proliferation of lens progenitors together with their morphogenetic movements results in the formation of the lens vesicle. This transient structure, comprised of lens precursor cells, is polarized with its anterior cells retaining their epithelial morphology and proliferative capacity, whereas the posterior lens precursor cells initiate terminal differentiation forming the primary lens fibers. Lens differentiation is marked by expression and accumulation of crystallins and other structural proteins. The transcriptional control of crystallin genes is characterized by the reiterative use of transcription factors required for the establishment of lens precursors in combination with more ubiquitously expressed factors (e.g. AP-1, AP-2α, CREB and USF) and recruitment of histone acetyltransferases (HATs) CBP and p300, and chromatin remodeling complexes SWI/SNF and ISWI. These studies have poised the study of lens development at the forefront of efforts to understand the connections between development, cell signaling, gene transcription and chromatin remodeling.

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A New Model for Olfactory Placode Development

Cited by 56 publications

References 56 publications

A role forfoxd3andsox10in the differentiation of gonadotropin-releasing hormone (GnRH) cells in the zebrafishDanio rerio

A role forfoxd3andsox10in the differentiation of gonadotropin-releasing hormone (GnRH) cells in the zebrafishDanio rerio

Cxcl12/Cxcr4 chemokine signaling is required for placode assembly and sensory axon pathfinding in the zebrafish olfactory system

Genetic and epigenetic mechanisms of gene regulation during lens development

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