Top PDF A Screen for Genes That Function Downstream of Ras1 During Drosophila Eye Development

A Screen for Genes That Function Downstream of Ras1 During Drosophila Eye Development

A Screen for Genes That Function Downstream of Ras1 During Drosophila Eye Development

Isolation of dominant suppressors and enhancers of ~ev-RaSl~'~: Genes encoding general factors involved in Rasl signal transduction are expected to function dur- ing [r]

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A Mosaic Genetic Screen Reveals Distinct Roles for trithorax and Polycomb Group Genes in Drosophila Eye Development

A Mosaic Genetic Screen Reveals Distinct Roles for trithorax and Polycomb Group Genes in Drosophila Eye Development

specification of a tissue, propagation of a signal, or cell- One target of Hh is atonal (ato), a proneural gene cell interactions leading to cell fate determination. The responsible for specifying the first photoreceptor, R8 eye imaginal disc is formed in the embryo and specified (Jarman et al. 1994; Dominguez 1999). The Notch path- in the second larval instar by a hierarchy of transcription way also contributes both to the initial activation of ato factors: the two Pax-6 homologs Twin of Eyeless (Toy) and to its restriction to a single cell (Cagan and Ready and Eyeless (Ey), the compound transcription factor 1989; Baker and Yu 1997; Baonza and Freeman 2001). formed by Eyes absent (Eya) and the homeodomain Once R8 has been determined, it recruits the remaining protein Sine oculis (So), and the Ski-related protein seven photoreceptors and four cone cells to the omma- Dachshund (Dac; Bonini et al. 1993; Mardon et al. 1994; tidium by secreting Spitz, a ligand for the epidermal Quiring et al. 1994; Chen et al. 1997; Pignoni et al. growth factor receptor (EGFR; Freeman 1996; Tio and 1997; Halder et al. 1998; Czerny et al. 1999). In the Moses 1997). Another gene activated by Hh is decapen- third instar, a wave of photoreceptor differentiation taplegic (dpp), which encodes a bone morphogenetic marked by an indentation called the morphogenetic protein-related signaling molecule (Heberlein et al. furrow propagates across the eye disc. This wave is driven 1993; Ma et al. 1993). Dpp activates the expression of by Hedgehog (Hh), a secreted protein first expressed hairy (h ), an inhibitor of Atonal function expressed in at the posterior margin of the disc and subsequently in a region anterior to the morphogenetic furrow, known the photoreceptors (Ready et al. 1976; Heberlein et al. as the preproneural zone (Greenwood and Struhl 1993; Ma et al. 1993). The eye disc differs from the wing 1999). In addition, Dpp represses homothorax (hth), and leg discs in that Hh indirectly activates its own which encodes a homeodomain protein that acts in expression in target cells, causing a dynamic expansion concert with Ey and the zinc-finger protein Teashirt of the Hh expression domain. When cells differentiate (Tsh) to repress expression of Eya, So, and Dac in the as photoreceptors, they are no longer able to respond anterior region of the eye disc (Bessa et al. 2002). Dpp to Hh; thus Hh target genes are only transiently acti- thus indirectly allows expression of these molecules in vated and must undergo rapid changes in their expres-
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Glial and Neuronal Functions of the Drosophila Homolog of the Human SWI/SNF Gene ATR-X (DATR-X) and the jing Zinc-Finger Gene Specify the Lateral Positioning of Longitudinal Glia and Axons

Glial and Neuronal Functions of the Drosophila Homolog of the Human SWI/SNF Gene ATR-X (DATR-X) and the jing Zinc-Finger Gene Specify the Lateral Positioning of Longitudinal Glia and Axons

factor was only partially required for axon scaffold formation in the Drosophila CNS. We therefore screened for gain-of-function enhancers of jing gain of function in the eye and identified the Drosophila homolog of the disease gene of human a-thalassemia/mental retardation X-linked (ATR-X) as well as other genes with potential roles in gene expression, translation, synaptic transmission, and cell cycle. jing and DATR-X reporter genes are expressed in both CNS neurons and glia, including the LG. Coexpression of jing and DATR-X in embryonic neurons synergistically affects longitudinal connective formation. During embryogenesis, jing and DATR-X have autonomous and nonautonomous roles in the lateral positioning of LG, neurons, and longitudinal axons as shown by cell-specific knockdown of gene expression. jing and DATR-X are also required autonomously for glial survival. jing and DATR-X mutations show synergistic effects during longitudinal axon formation suggesting that they are functionally related. These observations support a model in which downstream gene expression controlled by a potential DATR-X–Jing complex facilitates cellular positioning and axon guidance, ultimately allowing for proper connectivity in the developing Drosophila CNS.
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CREB Binding Protein Functions During Successive Stages of Eye Development in Drosophila

CREB Binding Protein Functions During Successive Stages of Eye Development in Drosophila

During the development of the compound eye of Drosophila several signaling pathways exert both positive and inhibitory influences upon an array of nuclear transcription factors to produce a near-perfect lattice of unit eyes or ommatidia. Individual cells within the eye are exposed to many extracellular signals, express multiple surface receptors, and make use of a large complement of cell-subtype-specific DNA-binding transcription factors. Despite this enormous complexity, each cell will make the correct developmental choice and adopt the appropriate cell fate. How this process is managed remains a poorly understood paradigm. Members of the CREB binding protein (CBP)/p300 family have been shown to influence development by (1) acting as bridging molecules between the basal transcriptional machinery and specific DNA-binding transcription factors, (2) physically interacting with terminal members of signaling cascades, (3) acting as transcriptional coactivators of downstream target genes, and (4) playing a key role in chromatin remodeling. In a screen for new genes involved in eye development we have identified the Drosophila homolog of CBP as a key player in both eye specification and cell fate determination. We have used a variety of approaches to define the role of CBP in eye development on a cell-by-cell basis.
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A Misexpression Screen Identifies Genes That Can Modulate RAS1 Pathway Signaling in Drosophila melanogaster

A Misexpression Screen Identifies Genes That Can Modulate RAS1 Pathway Signaling in Drosophila melanogaster

Differentiation of the R7 photoreceptor cell is dependent on the Sevenless receptor tyrosine kinase, which activates the RAS1/mitogen-activated protein kinase signaling cascade. Kinase suppressor of Ras (KSR) functions genetically downstream of RAS1 in this signal transduction cascade. Expression of domi- nant-negative KSR (KDN) in the developing eye blocks RAS pathway signaling, prevents R7 cell differentia- tion, and causes a rough eye phenotype. To identify genes that modulate RAS signaling, we screened for genes that alter RAS1/KSR signaling efficiency when misexpressed. In this screen, we recovered three known genes, Lk6, misshapen, and Akap200. We also identified seven previously undescribed genes; one encodes a novel rel domain member of the NFAT family, and six encode novel proteins. These genes may represent new components of the RAS pathway or components of other signaling pathways that can modulate signaling by RAS. We discuss the utility of gain-of-function screens in identifying new components of signaling pathways in Drosophila.
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Molecular Genetic Analysis of Drosophila eyes absent Mutants Reveals an Eye Enhancer Element

Molecular Genetic Analysis of Drosophila eyes absent Mutants Reveals an Eye Enhancer Element

D ROSOPHILA eye development is a genetic system al. 1997; Pignoni et al. 1997; Shen and Mardon 1997). in which it is possible to define molecular details dpp, a homologue of transforming growth factor-b of specification and differentiation of a neural structure. (Padgett et al. 1987), is also involved in appropriate Much research has focused on aspects of cell fate speci- regulation of these eye regulatory pathways and may fication and pattern formation of the retinal cells during also be required for ectopic eye induction (Chen et al. later stages of differentiation (reviewed in Zipursky and 1999). The eya gene appears to be a critical player in Rubin 1994; Treisman and Heberlein 1998). More eye formation, since it shows functional synergy with recent attention has focused on earlier events of eye both dac and so in directing eye development (Chen et specification, which has been shown to involve a set al. 1997; Pignoni et al. 1997). As the EYA protein also of genes highly conserved in vertebrates. These genes physically binds these proteins, EYA, DAC, and SO may include twin of eyeless (toy) and eyeless (ey), which are form a complex that is critical to eye specification. toy PAX-6 homeodomain homologues (Quiring et al. 1994; appears to function upstream of ey to activate ey expres- Czerny et al. 1999), sine oculis (so), which defines the sion (Czerny et al. 1999). For the other genes, it appears SIX class of vertebrate homeodomain homologies (Chey- that regulatory loops are involved, rather than there ette et al. 1994; Serikaku and O’Tousa 1994; Oliver being a linear pathway of eye specification, since expres- et al. 1995), dachshund (dac) and the vertebrate Dach sion of any one appears to turn on the expression and homologue (Mardon et al. 1994; Hammond et al. 1998), functionally require the other genes (previous refer- and eyes absent (eya) and the vertebrate Eya1, Eya2, and ences; Desplan 1997). Moreover, eya activity has multi- Eya3 genes (Bonini et al. 1993; Duncan et al. 1997; Xu ple downstream targets and may influence or be re- et al. 1997; Zimmerman et al. 1997). quired for a number of different processes of eye In Drosophila, ey was the first gene shown to display development (Pignoni et al. 1997; Hazelett et al. the dramatic capacity to direct eye formation when ec- 1998). To define additional molecular aspects of the topically expressed (Halder et al. 1995)—a property process of eye specification, we have focused on defining now known to be shared by dac, eya, and toy, and so molecular mechanisms of proper regulation of the eya when combined with eya (Bonini et al. 1997; Chen et gene in eye formation.
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An Overexpression Screen in Drosophila for Genes That Restrict Growth or Cell-Cycle Progression in the Developing Eye

An Overexpression Screen in Drosophila for Genes That Restrict Growth or Cell-Cycle Progression in the Developing Eye

A major advantage of performing a screen utilizing the EP lines is that the P-element insertion in most of the lines has been identified with respect to the completed genomic sequence. Thus the genes adjacent to the site of insertion of the P element can be identified rapidly. The 46 EP lines identified from the screen as having ey-GAL4-dependent reduced eye phenotypes represent insertions at 32 different genetic loci (Table 1). Thir- teen lines contain insertions in known genes. As ex- pected, some of these, including hedgehog (hh) and deca- pentaplegic (dpp), have well-characterized functions in eye development. Other genes identified include regu- lators of the cytoskeleton (Rac2 and pebble) and fringe (fng), a modulator of extracellular signals. Also identi- fied were Kruppel-homolog 1 (Kr-h1) and elbowB (elB), two putative transcriptional regulators. The remaining 19 loci have conceptual ORFs that have been identified by the sequencing project. Not all insertions were located Figure 1.—Adult eye phenotypes resulting from ey-GAL4- in the 5⬘ region of the ORFs. In one instance, the EP2340 directed expression of known negative regulators of the cell
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Ectopic Expression of the Drosophila Cdk1 Inhibitory Kinases, Wee1 and Myt1, Interferes With the Second Mitotic Wave and Disrupts Pattern Formation During Eye Development

Ectopic Expression of the Drosophila Cdk1 Inhibitory Kinases, Wee1 and Myt1, Interferes With the Second Mitotic Wave and Disrupts Pattern Formation During Eye Development

Wee1 kinases catalyze inhibitory phosphorylation of the mitotic regulator Cdk1, preventing mitosis during S phase and delaying it in response to DNA damage or developmental signals during G2. Unlike yeast, metazoans have two distinct Wee1-like kinases, a nuclear protein (Wee1) and a cytoplasmic protein (Myt1). We have isolated the genes encoding Drosophila Wee1 and Myt1 and are using genetic approaches to dissect their functions during normal development. Overexpression of Dwee1 or Dmyt1 during eye development generates a rough adult eye phenotype. The phenotype can be modified by altering the gene dosage of known regulators of the G2/M transition, suggesting that we could use these transgenic strains in modifier screens to identify potential regulators of Wee1 and Myt1. To confirm this idea, we tested a collection of deletions for loci that can modify the eye overexpression phenotypes and identified several loci as dominant modifiers. Mutations affecting the Delta/Notch signaling pathway strongly enhance a GMR-Dmyt1 eye phenotype but do not affect a GMR-Dwee1 eye phenotype, suggesting that Myt1 is potentially a downstream target for Notch activity during eye development. We also observed interactions with p53, which suggest that Wee1 and Myt1 activity can block apoptosis.
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A Gain-of-Function Screen for Genes That Affect the Development of the Drosophila Adult External Sensory Organ

A Gain-of-Function Screen for Genes That Affect the Development of the Drosophila Adult External Sensory Organ

to altered expression of insc, which serves an essential Ectopic supernumerary es organs: This subclass includes function in asymmetric divisions of delaminating neuro- big brain [EP(2)2278], a gene involved in lateral inhibi- blasts and embryonic muscle progenitor cell divisions tion that encodes a channel-like transmembrane pro- (Kraut et al. 1996; Carmena et al. 1998), requires fur- tein (Rao et al. 1990). Also in this subclass are two ther study. One potential complication is the presence genes with a known function in eye development: yan of the gene skittles, which encodes the phosphatidylinosi- [EP(2)0598 and EP(2)2500], which encodes an ETS do- tol 4-phosphate 5-kinase, in the first intron of insc. Mis- main nuclear protein that has an essential function in expression of skittles has been shown to generate ectopic photoreceptor cell development (Lai and Rubin 1992; es organs (Hassan et al. 1998). It is not clear whether O’Neill et al. 1994); and hedgehog [EP(3)3521], which is misexpression of insc, skittles, or both is driven by involved in multiple developmental processes including
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Lobe and Serrate are required for cell survival during
early eye development in Drosophila

Lobe and Serrate are required for cell survival during early eye development in Drosophila

ventral eye (Chern and Choi, 2002; Singh and Choi, 2003; Singh et al., 2005a; Singh et al., 2005b). During early eye development, little or no cell death is observed. At the mid-pupal stage, programmed cell death plays an important role in the selective removal of a large number of excess undifferentiated cells in the interommatidial space that fail to be recruited to the ommatidia (Miller and Cagan, 1998; Rusconi et al., 2000). During this time window of pupal development, EGFR and Ras act as survival cues (Silver and Rebay, 2005; Bergmann et al., 2002; Yang and Baker, 2003). Surprisingly, there is little information concerning genes responsible for cell survival during early larval eye imaginal disc development. Our studies show that, during early eye development, L and Ser are required for the survival of ventral eye cells. We found that one of the major reasons for the elimination of the ventral eye cells in L/Ser mutants is due to the induction of caspase-dependent cell death. We found that L- and Ser-mutant phenotypes can be rescued by blocking inappropriate induction of (i) Wg, (ii) JNK-signaling-mediated cell death and (iii) caspase-dependent cell death.
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ISOLATION AND CHARACTERIZATION OF SEX-LINKED FEMALE-STERILE MUTANTS IN DROSOPHILA MELANOGASTER WITH SPECIAL ATTENTION TO EGGSHELL MUTANTS

ISOLATION AND CHARACTERIZATION OF SEX-LINKED FEMALE-STERILE MUTANTS IN DROSOPHILA MELANOGASTER WITH SPECIAL ATTENTION TO EGGSHELL MUTANTS

Roles of ecdysone in Drosophila development. Organization of a cluster of four chorion genes in Drosophila and its relationship to developmental expression and amplificatio[r]

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The Drosophila retained/dead ringer gene and ARID gene family function during development

The Drosophila retained/dead ringer gene and ARID gene family function during development

in the heart, liver, neural tube, spleen and thymus (Takeuchi et al., 1995; Kitajima et al., 2001). Detailed analysis of jumonji mutant tissues revealed that cardiac trabecular myocytes in the heart and lymphoid cells (megakaryocytes) in all hematopoetic tissues showed over-proliferation and overgrowth (Kitajima et al., 2001). retn/dri appears not to be expressed in all dividing cells, so it is unlikely that it is required in all mitotic divisions in the same way that RBP1 may be generally required. Furthermore, analysis of the phenotypes later in development has not revealed any re- quirement for RETN/DRI in later divisions, nor has it revealed any overgrowth phenotype that would indicate a negative regulatory role of the type inferred for mouse jumonji. However, the cleavage divisions in the Drosophila embryo are highly modified divisions, being syncytial and occurring every approximately 10 minutes. It is possible that RETN/DRI has been recruited to facilitate these extraordinarily rapid early embryonic mitotic cycles.
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A Screen for Genes Regulating the Wingless Gradient in Drosophila Embryos

A Screen for Genes Regulating the Wingless Gradient in Drosophila Embryos

dynamin-independent process. Development 131: 601–611. Daniel St. Johnston and Jean-Paul Vincent for their comments on the Han, C., T. Y. Belenkaya, M. Khodoun, M. Tauchi and X. Lin, manuscript, and Francois Balloux for advice on the statistics. We also 2004b Distinct and collaborative roles of Drosophila EXT family thank K. Cadigan, S. Cohen, M. Fortini, D. Kalderon, S. Kerridge, proteins in morphogen signalling and gradient formation. Devel- D. St Johnston, G. Struhl, J. Treisman, the Hybridoma Bank, the opment 131: 1563–1575.

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A Genetic Screen for Novel Components of the Notch Signaling Pathway During Drosophila Bristle Development

A Genetic Screen for Novel Components of the Notch Signaling Pathway During Drosophila Bristle Development

segregation of epidermal and sensory organ precursor lineages, thus inhibiting bristle formation. Mutations that reduce Notch signaling suppress this phenotype. This screen of approximately 50,000 flies led to the identification of a small number of dominant suppressors in seven complementation groups. These include known components in the pathway, Notch, mastermind, Delta, and Hairless, as well as two novel mutations. The first, A122, appears to interact with Notch only during bristle development. The other, M285, displays extensive genetic interactions with the Notch pathway elements and appears, in general, capable of suppressing Notch gain-of-function phenotypes while enhancing Notch loss-of-function phenotypes, sug- gesting that it plays an important role in Notch signaling.
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Wollknäuel is required for embryo patterning and encodes the
Drosophila ALG5 UDP glucose:dolichyl phosphate
glucosyltransferase

Wollknäuel is required for embryo patterning and encodes the Drosophila ALG5 UDP glucose:dolichyl phosphate glucosyltransferase

Taken together, these results confirm that the UPR is activated in wol mutants, and indicate that translation might be attenuated in wol embryos. We propose that this causes the observed patterning defects. According to this model, reduced maternal wol activity would lead to accumulation of unfolded proteins in the ER in early embryos, with a consequent transient increase in eIF2 α phosphorylation. Translation of selected maternal mRNAs, including cad and the activator of dpp expression, would be particularly sensitive to increased eIF2 α phosphorylation. Reduced amounts of these transcription factors result in disruption of posterior segmentation and of dorsal-ventral patterning. Although the UPR plays important developmental and physiological roles in C. elegans, Drosophila and mammals (Ryoo et al., 2007; Shen et al., 2001; Shen et al., 2005; Souid et al., 2007; Wu and Kaufman, 2006), this is the first report to indicate that inappropriate UPR activation may disrupt embryonic patterning.
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The pleiotropic function of Delta during postembryonic development of Drosophila melanogaster.

The pleiotropic function of Delta during postembryonic development of Drosophila melanogaster.

Analysis of the development of Delta ( D l ) temperature-sensitive mutants pulsed at restrictive temperature during larval and pupal stages reveals multiple phenocrit[r]

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A Screen to Identify Drosophila Genes Required for Integrin-Mediated Adhesion

A Screen to Identify Drosophila Genes Required for Integrin-Mediated Adhesion

inflated, which encodes an integrin a subunit. (B) Loci identi- if this distribution of genes were representative, we fied in the screen (see also Table 1). Each line indicates a would expect to recover only 16 additional loci by chromosome, and the complementation groups isolated in screening the autosomes, indicating that the screen is the screens are indicated. Newly identified loci are depicted

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Tissue specific distribution and variation of the channel forming protein ductin during development of Drosophila melanogaster

Tissue specific distribution and variation of the channel forming protein ductin during development of Drosophila melanogaster

V-ATPases are required for the acidification of many types of organelles (for reviews, see Nelson, 1992; Finbow and Harrison, 1997). In the Drosophila ovary, V-ATPases are presumed to generate the low pH of lysosomes or small vesicles, in which ligand-receptor complexes become dissociated, whilst during embryogenesis, V-ATPases are likely to be necessary for the processing of yolk (Bohrmann and Braun, 1999). V-ATPases coupled to secondary active antiport mechanisms appear to energize transport processes across plasma membranes in many species (for reviews, see Wieczorek, 1992; Harvey and Wieczorek, 1997). In insects, V-ATPases have been detected in the plasma membranes of several cell types: for example, in the midgut of Manduca (Jäger et al., 1996), Heliothis (Pietrantonio and Gill, 1997) and Aedes (Gill et al., 1998); in Malpighian tubules of Formica (Garayoa et al., 1995), Heliothis (Pietrantonio and Gill, 1995), Drosophila (Dow et al., 1997) and Aedes (Gill et al., 1998); in salivary glands of Periplaneta (Just and Walz, 1994); and in ovarian follicles of Manduca (Janssen et al., 1995), Hyalophora (Wang and Telfer, 1998) and Drosophila (Bohrmann and Braun, 1999). In the present study, plasma membrane-associated puta- tive V-ATPases were detected in cells of the midgut, the salivary gland and the muscles, whereas vesicle-associated V-ATPases were found in almost every analysed cell type.
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VARIEGATION IN THE ZESTE EYE COLOR ALLELES AND ITS BEARING ON GENE ACTION DURING THE DEVELOPMENT OF THE EYE OF DROSOPHILA MELANOGASTER

VARIEGATION IN THE ZESTE EYE COLOR ALLELES AND ITS BEARING ON GENE ACTION DURING THE DEVELOPMENT OF THE EYE OF DROSOPHILA MELANOGASTER

One principal difference between the action of the zeste alleles zm and z z and the action of the Lobe allele is, then, that the determination of red pigment for- mation i[r]

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Genome-wide screen for modifiers of Parkinson's disease genes in Drosophila

Genome-wide screen for modifiers of Parkinson's disease genes in Drosophila

A previous study by Pallanck and colleagues screened a collection of P-element insertions (covering less than 10% of the fly genome) that modify the partial lethality of park null mutants [30]. However, since their screen was conducted in homozygous park null mutant back- ground, less than 10% of the fly genome was covered. To increase the coverage, we developed an RNAi-based strategy, which allowed us to perform a F1 screen that covered >80% of the fly genome. Several PD-interacting genes identified by Pallanck and colleagues in their pre- vious screen [30], are located within PD-interacting cytological regions identified from our screen. For instance, Glutathione S-transferase 1 (Gst1) and Thiore- doxin-2 (Trx-2) are located in PD-interacting cytological regions uncovered by Df(2R)BSC49 (Table 6) and Df(2L) N22-14 (Table 3), respectively.
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