A glimpse into dorso-ventral patterning of the Drosophila eye

Department of Biology, University of Dayton, Dayton, Ohio 45469, USA.
Developmental Dynamics (Impact Factor: 2.38). 01/2012; 241(1):69-84. DOI: 10.1002/dvdy.22764
Source: PubMed


During organogenesis in all multi-cellular organisms, axial patterning is required to transform a single layer organ primordium into a three-dimensional organ. The Drosophila eye model serves as an excellent model to study axial patterning. Dorso-ventral (DV) axis determination is the first lineage restriction event during axial patterning of the Drosophila eye. The early Drosophila eye primordium has a default ventral fate, and the dorsal eye fate is established by onset of dorsal selector gene pannier (pnr) expression in a group of cells on the dorsal eye margin. The boundary between dorsal and ventral compartments called the equator is the site for Notch (N) activation, which triggers cell proliferation and differentiation. This review will focus on (1) chronology of events during DV axis determination; (2) how early division of eye into dorsal and ventral compartments contributes towards the growth and patterning of the fly retina, and (3) functions of DV patterning genes.

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    • "These cells proliferate during each of the three larval instar stages to form morphologically distinct tissues, then differentiate during pupation in response to the steroid hormone 20-hydroxyecdysone to give rise to the adult appendages and other parts of the head, thorax, and abdomen (Ursprung and Nöthiger 1972). Studies of imaginal disc biology have made significant contributions to axis specification and patterning (Estella et al. 2012; Singh et al. 2012), induction and signal transduction (Ramírez-Weber and Kornberg 2000; Swarup and Verheyen 2012), cell fate specification and differentiation (Furman and Bukharina 2012; Treisman 2013), cell growth and proliferation (Wartlick et al. 2011; Baena-Lopez et al. 2012), cell and tissue polarity (Mlodzik 1999; Müller 2000), and sex determination (Sánchez and Guerrero 2001; Estrada et al. 2003). Research using imaginal discs has also proven fruitful for Copyright © 2015 Smith et al. doi: 10.1534/g3.115.019810 "
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    ABSTRACT: Drosophila imaginal discs provide an ideal model to study processes important for cell signaling and cell specification, tissue differentiation, and cell competition during development. One challenge to understanding genetic control of cellular processes and cell interactions is difficulty in effectively targeting a defined subset of cells in developing tissues in gene manipulation experiments. A recently developed Flippase-induced intersectional GAL80/GAL4 repression method incorporates several gene manipulation technologies in Drosophila to enable such fine-scale dissection in neural tissues. In particular, this approach brings together existing GAL4 transgenes, newly developed enhancer-trap flippase transgenes, and GAL80 transgenes flanked by Flippase recognition target sites. The combination of these tools enables gene activation/repression in particular subsets of cells within a GAL4 expression pattern. Here, we expand the utility of a large collection of these enhancer-trap flippase transgenic insertion lines by characterizing their expression patterns in third larval instar imaginal discs. We screened 521 different enhancer-trap flippase lines and identified 28 that are expressed in imaginal tissues, including two transgenes that show sex-specific expression patterns. Using a line that expresses Flippase in the wing imaginal disc, we demonstrate the utility of this intersectional approach for studying development by knocking down gene expression of a key member of the planar cell polarity pathway. The results of our experiments show that these enhancer-trap flippase lines enable fine-scale manipulation in imaginal discs. Copyright © 2015 Author et al.
    G3-Genes Genomes Genetics 08/2015; 5(10). DOI:10.1534/g3.115.019810 · 3.20 Impact Factor
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    • "Tsh is known to be involved in regulating retinal development in Drosophila and has the capability to induce ectopic eyes [31]. Since our disease model is restricted to the retina of the fly, we wanted to test if the neuroprotective function of Tsh is mediated through its role in the retinal differentiation pathway [19,31,46,48,78]. "
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    ABSTRACT: Alzheimer's disease (AD) is a debilitating age related progressive neurodegenerative disorder characterized by the loss of cognition, and eventual death of the affected individual. One of the major causes of AD is the accumulation of Amyloid-beta 42 (Aβ42) polypeptides formed by the improper cleavage of amyloid precursor protein (APP) in the brain. These plaques disrupt normal cellular processes through oxidative stress and aberrant signaling resulting in the loss of synaptic activity and death of the neurons. However, the detailed genetic mechanism(s) responsible for this neurodegeneration still remain elusive. We have generated a transgenic Drosophila eye model where high levels of human Aβ42 is misexpressed in the differentiating photoreceptor neurons of the developing eye, which phenocopy Alzheimer's like neuropathology in the neural retina. We have utilized this model for a gain of function screen using members of various signaling pathways involved in the development of the fly eye to identify downstream targets or modifiers of Aβ42 mediated neurodegeneration. We have identified the homeotic gene teashirt (tsh) as a suppressor of the Aβ42 mediated neurodegenerative phenotype. Targeted misexpression of tsh with Aβ42 in the differentiating retina can significantly rescue neurodegeneration by blocking cell death. We found that Tsh protein is absent/ downregulated in the neural retina at this stage. The structure function analysis revealed that the PLDLS domain of Tsh acts as an inhibitor of the neuroprotective function of tsh in the Drosophila eye model. Lastly, we found that the tsh paralog, tiptop (tio) can also rescue Aβ42 mediated neurodegeneration. We have identified tsh and tio as new genetic modifiers of Aβ42 mediated neurodegeneration. Our studies demonstrate a novel neuroprotective function of tsh and its paralog tio in Aβ42 mediated neurodegeneration. The neuroprotective function of tsh is independent of its role in retinal determination.
    PLoS ONE 11/2013; 8(11):e80829. DOI:10.1371/journal.pone.0080829 · 3.23 Impact Factor
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    • "Most of these strategies provide excellent tools for generation of clones in the entire developing eye field. During organogenesis, a developing field gets further subdivided into smaller regions called compartments (Blair, 2001; Curtiss et al., 2002; Dahmann et al., 2011; Singh et al., 2012). The properties of the cells of a compartment are unique and the cells within a compartment behave differently based on their response to the morphogen gradients. "
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    ABSTRACT: Genetic mosaic approach is commonly employed in the Drosophila eye by completely abolishing or misexpressing a gene within a subset of cells to unravel its role during development. Classical genetic mosaic approach involves random clone generation in all developing fields. Consequently, a large sample size needs to be screened to generate and analyze clones in specific domains of the developing eye. To address domain specific functions of genes during axial patterning, we have developed a system for generating mosaic clones by combining Gal4/UAS and FLP/FRT system which will allow generation of loss-of-function as well as gain-of-function clones on the dorsal and ventral eye margins. We used the bifid-Gal4 driver to drive expression of UAS-flippase (FLP). This reagent can have multiple applications in (i) studying spatio-temporal function of a gene during dorso-ventral axis specification in the eye, (ii) analyzing genetic epistasis of genes involved in DV patterning and (iii) conducting genome wide screens in a domain specific manner. © 2012 Wiley Periodicals, Inc.
    genesis 01/2013; 51(1). DOI:10.1002/dvg.22355 · 2.02 Impact Factor
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