scholarly journals Transcriptional regulation of atonal required for Drosophila larval eye development by concerted action of eyes absent, sine oculis and hedgehog signaling independent of fused kinase and cubitus interruptus

Development ◽  
2000 ◽  
Vol 127 (7) ◽  
pp. 1531-1540 ◽  
Author(s):  
T. Suzuki ◽  
K. Saigo
Keyword(s):  
Hedgehog Signaling ◽  
Specific Antigen ◽  
Photoreceptor Cells ◽  
Organ Development ◽  
Cubitus Interruptus ◽  
Eyes Absent ◽  
Organ Formation ◽  
Sine Oculis ◽  
Founder Cells ◽  
Bolwig's Organ

Bolwig's organ is the larval light-sensing system consisting of 12 photoreceptors and its development requires atonal activity. Here, we showed that Bolwig's organ formation and atonal expression are controlled by the concerted function of hedgehog, eyes absent and sine oculis. Bolwig's organ primordium was first detected as a cluster of about 14 Atonal-positive cells at the posterior edge of the ocular segment in embryos and hence, atonal expression may define the region from which a few Atonal-positive founder cells (future primary photoreceptor cells) are generated by lateral specification. In Bolwig's organ development, neural differentiation precedes photoreceptor specification, since Elav, a neuron-specific antigen, whose expression is under the control of atonal, is expressed in virtually all early-Atonal-positive cells prior to the establishment of founder cells. Neither Atonal expression nor Bolwig's organ formation occurred in the absence of hedgehog, eyes absent or sine oculis activity. Genetic and histochemical analyses indicated that (1) responsible Hedgehog signals derive from the ocular segment, (2) Eyes absent and Sine oculis act downstream of or in parallel with Hedgehog signaling and (3) the Hedgehog signaling pathway required for Bolwig's organ development is a new type and lacks Fused kinase and Cubitus interruptus as downstream components.

scholarly journals sine oculis is a homeobox gene required for Drosophila visual system development.

Genetics ◽  
1994 ◽  
Vol 138 (4) ◽  
pp. 1137-1150 ◽  
Author(s):  
M A Serikaku ◽  
J E O'Tousa
Keyword(s):  
Embryonic Development ◽  
Visual System ◽  
Gene Product ◽  
Optic Lobe ◽  
System Development ◽  
Photoreceptor Cells ◽  
P Element ◽  
Sine Oculis ◽  
Visual System Development ◽  
Bolwig's Organ

Abstract The somda (sine oculis-medusa) mutant is the result of a P element insertion at position 43C on the second chromosome. somda causes aberrant development of the larval photoreceptor (Bolwig's) organ and the optic lobe primordium in the embryo. Later in development, adult photoreceptors fail to project axons into the optic ganglion. Consequently optic lobe development is aborted and photoreceptor cells show age-dependent retinal degeneration. The so gene was isolated and characterized. The gene encodes a homeodomain protein expressed in the optic lobe primordium and Bolwig's organ of embryos, in the developing adult visual system of larvae, and in photoreceptor cells and optic lobes of adults. In addition, the SO product is found at invagination sites during embryonic development: at the stomadeal invagination, the cephalic furrow, and at segmental boundaries. The mutant somda allele causes severe reduction of SO embryonic expression but maintains adult visual system expression. Ubiquitous expression of the SO gene product in 4-8-hr embryos rescues all somda mutant abnormalities, including the adult phenotypes. Thus, all deficits in adult visual system development and function results from failure to properly express the so gene during embryonic development. This analysis shows that the homeodomain containing SO gene product is involved in the specification of the larval and adult visual system development during embryogenesis.

The control of cell fate in the embryonic visual system by atonal, tailless and EGFR signaling

Development ◽  
1999 ◽  
Vol 126 (13) ◽  
pp. 2945-2954 ◽  
Author(s):  
A. Daniel ◽  
K. Dumstrei ◽  
J.A. Lengyel ◽  
V. Hartenstein
Keyword(s):  
Visual System ◽  
Cell Fate ◽  
Optic Lobe ◽  
Egfr Signaling ◽  
Phenotypic Analysis ◽  
Eyes Absent ◽  
Sine Oculis ◽  
Bolwig's Organ ◽  
Encoding Genes

We describe here the role of the transcription factors encoding genes tailless (tll), atonal (ato), sine oculis (so), eyeless (ey) and eyes absent (eya), and EGFR signaling in establishing the Drosophila embryonic visual system. The embryonic visual system consists of the optic lobe primordium, which, during later larval life, develops into the prominent optic lobe neuropiles, and the larval photoreceptor (Bolwig's organ). Both structures derive from a neurectodermal placode in the embryonic head. Expression of tll is normally confined to the optic lobe primordium, whereas ato appears in a subset of Bolwig's organ cells that we call Bolwig's organ founders. Phenotypic analysis, using specific markers for Bolwig's organ and the optic lobe, of tll loss- and gain-of-function mutant embryos reveals that tll functions to drive cells to optic lobe as opposed to Bolwig's organ fate. Similar experiments indicate that ato has the opposite effect, namely driving cells to a Bolwig's organ fate. Since we can show that tll and ato do not regulate each other, we propose a model wherein tll expression restricts the ability of cells to respond to signaling arising from ato-expressing Bolwig's organ pioneers. Our data further suggest that the Bolwig's organ founder cells produce Spitz (the Drosophila TGFalpha homolog) signal, which is passed to the neighboring secondary Bolwig's organ cells where it activates the EGFR signaling cascade and maintains the fate of these secondary cells. The regulators of tll expression in the embryonic visual system remain elusive, as we were unable to find evidence for regulation by the ‘early eye genes’ so, eya and ey, or by EGFR signaling.

Proteolysis of cubitus interruptus in Drosophila requires phosphorylation by protein kinase A

Development ◽  
1999 ◽  
Vol 126 (19) ◽  
pp. 4331-4339 ◽  
Author(s):  
M.A. Price ◽  
D. Kalderon
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Hedgehog Signaling ◽  
Target Genes ◽  
Ectopic Expression ◽  
Full Length ◽  
Mutant Form ◽  
Wild Type ◽  
Cubitus Interruptus ◽  
Kinase A

The Hedgehog signal transduction pathway is involved in diverse patterning events in many organisms. In Drosophila, Hedgehog signaling regulates transcription of target genes by modifying the activity of the DNA-binding protein Cubitus interruptus (Ci). Hedgehog signaling inhibits proteolytic cleavage of full-length Ci (Ci-155) to Ci-75, a form that represses some target genes, and also converts the full-length form to a potent transcriptional activator. Reduction of protein kinase A (PKA) activity also leads to accumulation of full-length Ci and to ectopic expression of Hedgehog target genes, prompting the hypothesis that PKA might normally promote cleavage to Ci-75 by directly phosphorylating Ci-155. Here we show that a mutant form of Ci lacking five potential PKA phosphorylation sites (Ci5m) is not detectably cleaved to Ci-75 in Drosophila embryos. Moreover, changes in PKA activity dramatically altered levels of full-length wild-type Ci in embryos and imaginal discs, but did not significantly alter full-length Ci5m levels. We corroborate these results by showing that Ci5m is more active than wild-type Ci at inducing ectopic transcription of the Hh target gene wingless in embryos and that inhibition of PKA enhances induction of wingless by wild-type Ci but not by Ci5m. We therefore propose that PKA phosphorylation of Ci is required for the proteolysis of Ci-155 to Ci-75 in vivo. We also show that the activity of Ci5m remains Hedgehog responsive if expressed at low levels, providing further evidence that the full-length form of Ci undergoes a Hedgehog-dependent activation step.

scholarly journals Wingless and Hedgehog signaling pathways regulate orthodenticle and eyes absent during ocelli development in Drosophila

2009 ◽  
Vol 329 (1) ◽  
pp. 104-115 ◽  
Author(s):  
Jorge Blanco ◽  
Makiko Seimiya ◽  
Tobias Pauli ◽  
Heinrich Reichert ◽  
Walter J. Gehring
Keyword(s):  
Signaling Pathways ◽  
Hedgehog Signaling ◽  
Eyes Absent

scholarly journals The Hippo pathway coactivator Yorkie can reprogram cell fates and create compartment-boundary–like interactions at clone margins

2020 ◽  
Vol 6 (50) ◽  
pp. eabe8159
Author(s):  
Joanna C. D. Bairzin ◽  
Maya Emmons-Bell ◽  
Iswar K. Hariharan
Keyword(s):  
Hedgehog Signaling ◽  
Hippo Pathway ◽  
Activity Levels ◽  
Cell Fates ◽  
Cubitus Interruptus ◽  
Compartment Boundary ◽  
Pathway Activation ◽  
Chromatin Regulator ◽  
Heterotypic Interactions ◽  
The Hippo Pathway

During development, tissue-specific patterns of gene expression are established by transcription factors and then stably maintained via epigenetic mechanisms. Cancer cells often express genes that are inappropriate for that tissue or developmental stage. Here, we show that high activity levels of Yki, the Hippo pathway coactivator that causes overgrowth in Drosophila imaginal discs, can also disrupt cell fates by altering expression of selector genes like engrailed (en) and Ultrabithorax (Ubx). Posterior clones expressing activated Yki can down-regulate en and express an anterior selector gene, cubitus interruptus (ci). The microRNA bantam and the chromatin regulator Taranis both function downstream of Yki in promoting ci expression. The boundary between Yki-expressing posterior clones and surrounding wild-type cells acquires properties reminiscent of the anteroposterior compartment boundary; Hedgehog signaling pathway activation results in production of Dpp. Thus, at least in principle, heterotypic interactions between Yki-expressing cells and their neighbors could activate boundary-specific signaling mechanisms.

scholarly journals Identification of novel direct targets of Drosophila Sine oculis and Eyes absent by integration of genome-wide data sets

2016 ◽  
Vol 415 (1) ◽  
pp. 157-167 ◽  
Author(s):  
Meng Jin ◽  
Sara Aibar ◽  
Zhongqi Ge ◽  
Rui Chen ◽  
Stein Aerts ◽  
...  
Keyword(s):  
Data Sets ◽  
Eyes Absent ◽  
Sine Oculis ◽  
Genome Wide ◽  
Genome Wide Data

Diminished Sonic hedgehog signaling and lack of floor plate differentiation in Gli2 mutant mice

Development ◽  
1998 ◽  
Vol 125 (14) ◽  
pp. 2533-2543 ◽  
Author(s):  
Q. Ding ◽  
J. Motoyama ◽  
S. Gasca ◽  
R. Mo ◽  
H. Sasaki ◽  
...  
Keyword(s):  
Sonic Hedgehog ◽  
Motor Neurons ◽  
Neural Tube ◽  
Hedgehog Signaling ◽  
Zinc Finger Protein ◽  
Floor Plate ◽  
Mutant Mice ◽  
Sonic Hedgehog Signaling ◽  
Cubitus Interruptus ◽  
High Level

Floor plate cells at the midline of the neural tube are specified by high-level activity of Sonic hedgehog (Shh) secreted by notochord, whereas motor neurons are thought to be specified by a lower level activity of Shh secreted in turn by floor plate cells. In Drosophila, the Gli zinc finger protein Cubitus interruptus functions as a transcription factor activating Hedgehog-responsive genes. We report that the expression of known Shh-responsive genes such as Ptc and Gli1 is downregulated in mutant mice lacking Gli2 function. Gli2 mutants fail to develop a floor plate yet still develop motor neurons, which occupy the ventral midline of the neural tube. Our results imply that Gli2 is required to mediate high level but not low level Shh activity and show that the development of motor neurons can occur in the absence of floor plate induction.

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