hairy gene function in the Drosophila eye: normal expression is dispensable but ectopic expression alters cell fates

Development ◽  
1991 ◽  
Vol 113 (4) ◽  
pp. 1245-1256 ◽  
Author(s):  
N.L. Brown ◽  
C.A. Sattler ◽  
D.R. Markey ◽  
S.B. Carroll
Keyword(s):  
Regulatory Gene ◽  
Ectopic Expression ◽  
Photoreceptor Cells ◽  
Cell Fates ◽  
Eye Disc ◽  
Normal Expression ◽  
Segmentation Gene Expression ◽  
Sensory Structures ◽  
Two Stages ◽  
Eye Imaginal Disc

The regulatory gene hairy is expressed and required during early embryogenesis to control segmentation gene expression properly and during larval and pupal development to control the pattern of certain adult sensory structures. We have found the hairy protein to be expressed transiently during two stages of eye imaginal disc development, including all cells immediately anterior to the morphogenetic furrow that traverses the developing eye disc, and again in the presumptive R7 photoreceptor cells of the developing ommatidia. This pattern is conserved in a significantly diverged Drosophila species. We show that, surprisingly, ommatidia formed by homozygous hairy- mutant clones are apparently normal, indicating that hairy function in the eye is dispensable. However, we do find that ectopic expression of hairy causes numerous structural abnormalities and the alteration of cell fates. Thus, proper regulation of hairy is still essential for normal eye development. We suggest that the loss of hairy function may be compensated by other regulatory proteins, as has been observed previously for several structurally and functionally related genes involved in sensory organ development. The effects of ectopic hairy expression may result from interactions with proneural genes involved in the development of the eye and other sensory organs.

The cell adhesion molecule Echinoid defines a new pathway that antagonizes the Drosophila EGF receptor signaling pathway

Development ◽  
2001 ◽  
Vol 128 (4) ◽  
pp. 591-601 ◽  
Author(s):  
J. Bai ◽  
W. Chiu ◽  
J. Wang ◽  
T. Tzeng ◽  
N. Perrimon ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Adhesion Molecule ◽  
Cell Adhesion Molecule ◽  
Egf Receptor ◽  
Ectopic Expression ◽  
Growth Factor Receptor ◽  
Photoreceptor Cells ◽  
Egfr Signaling ◽  
Eye Disc ◽  
Cone Cells

Photoreceptor and cone cells in the Drosophila eye are recruited following activation of the epidermal growth factor receptor (EGFR) pathway. We have identified echinoid (ed) as a novel putative cell adhesion molecule that negatively regulates EGFR signaling. The ed mutant phenotype is associated with extra photoreceptor and cone cells. Conversely, ectopic expression of ed in the eye leads to a reduction in the number of photoreceptor cells. ed expression is independent of EGFR signaling and ED is localized to the plasma membrane of every cells throughout the eye disc. We present evidence that ed acts nonautonomously to generate extra R7 cells by a mechanism that is sina-independent but upstream of Tramtrack (TTK88). Together, our results support a model whereby ED defines an independent pathway that antagonizes EGFR signaling by regulating the activity, but not the level, of the TTK88 transcriptional repressor.

wingless inhibits morphogenetic furrow movement in the Drosophila eye disc

Development ◽  
1995 ◽  
Vol 121 (11) ◽  
pp. 3519-3527 ◽  
Author(s):  
J.E. Treisman ◽  
G.M. Rubin
Keyword(s):  
Posterior Margin ◽  
Ectopic Expression ◽  
Spatial Localization ◽  
Morphogenetic Furrow ◽  
Differentiated Cells ◽  
Repetitive Process ◽  
Eye Disc ◽  
Drosophila Eye ◽  
Lateral Margins ◽  
Eye Imaginal Disc

Differentiation of the Drosophila eye imaginal disc is an asynchronous, repetitive process which proceeds across the disc from posterior to anterior. Its propagation correlates with the expression of decapentaplegic at the front of differentiation, in the morphogenetic furrow. Both differentiation and decapentaplegic expression are maintained by Hedgehog protein secreted by the differentiated cells posterior to the furrow. However, their initiation at the posterior margin occurs prior to hedgehog expression by an unknown mechanism. We show here that the wingless gene contributes to the correct spatial localization of initiation. Initiation of the morphogenetic furrow is restricted to the posterior margin by the presence of wingless at the lateral margins; removal of wingless allows lateral initiation. Ectopic expression of wingless at the posterior margin can also inhibit normal initiation. In addition, the presence of wingless in the center of the disc can prevent furrow progression. These effects of wingless are achieved without altering the expression of decapentaplegic.

Ectopic expression of BEAF32A in the Drosophila eye imaginal disc inhibits differentiation of photoreceptor cells and induces apoptosis

Chromosoma ◽  
2001 ◽  
Vol 110 (5) ◽  
pp. 313-321 ◽  
Author(s):  
Masamitsu Yamaguchi ◽  
Hideki Yoshida ◽  
Fumiko Hirose ◽  
Yoshihiro H. Inoue ◽  
Yuko Hayashi ◽  
...  
Keyword(s):  
Imaginal Disc ◽  
Ectopic Expression ◽  
Photoreceptor Cells ◽  
Drosophila Eye ◽  
Eye Imaginal Disc

The sidekick gene, a member of the immunoglobulin superfamily, is required for pattern formation in the Drosophila eye

Development ◽  
1997 ◽  
Vol 124 (17) ◽  
pp. 3303-3312 ◽  
Author(s):  
D.N. Nguyen ◽  
Y. Liu ◽  
M.L. Litsky ◽  
R. Reinke
Keyword(s):  
Temporal Order ◽  
Transmembrane Domain ◽  
Photoreceptor Cells ◽  
Cell Interaction ◽  
Immunoglobulin Superfamily ◽  
Eye Disc ◽  
Mosaic Analysis ◽  
Drosophila Eye ◽  
Undifferentiated Cells ◽  
Eye Imaginal Disc

In the Drosophila eye imaginal disc the photoreceptor cells (R cells) differentiate according to a precise spatial and temporal order. The sidekick (sdk) gene is necessary to prevent extra R cells from differentiating during eye disc development. The extra cell appears between R3 and R4 early in R cell clusters and is most likely the result of the mystery cell inappropriately differentiating as an R cell. Mosaic analysis shows that sdk is required neither in the R cells nor in the extra cell, suggesting that sdk is necessary in the surrounding undifferentiated cells. The sdk gene codes for a protein that is a member of the immunoglobulin superfamily, having six immunoglobulin domains, thirteen fibronectin repeats and a transmembrane domain. The protein structure is consistent with its participation in cell-cell interaction during eye development.

Role of decapentaplegic in initiation and progression of the morphogenetic furrow in the developing Drosophila retina

Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 559-567 ◽  
Author(s):  
F. Chanut ◽  
U. Heberlein
Keyword(s):  
Posterior Margin ◽  
Imaginal Disc ◽  
Photoreceptor Cells ◽  
Morphogenetic Furrow ◽  
Retinal Differentiation ◽  
Eye Disc ◽  
Forward Edge ◽  
Eye Imaginal Disc ◽  
Precise Role

Morphogenesis in the Drosophila retina initiates at the posterior margin of the eye imaginal disc by an unknown mechanism. Upon initiation, a wave of differentiation, its forward edge marked by the morphogenetic furrow (MF), proceeds anteriorly across the disc. Progression of the MF is driven by hedgehog (hh), expressed by differentiating photoreceptor cells. The TGF-beta homolog encoded by decapentaplegic (dpp) is expressed at the disc's posterior margin prior to initiation and in the furrow, under the control of hh, during MF progression. While dpp has been implicated in eye disc growth and morphogenesis, its precise role in retinal differentiation has not been determined. To address the role of dpp in initiation and progression of retinal differentiation we analyzed the consequences of reduced and increased dpp function during eye development. We find that dpp is not only required for normal MF initiation, but is sufficient to induce ectopic initiation of differentiation. Inappropriate initiation is normally inhibited by wingless (wg). Loss of dpp function is accompanied by expansion of wg expression, while increased dpp function leads to loss of wg transcription. In addition, dpp is required to maintain, and sufficient to induce, its own expression along the disc's margins. We postulate that dpp autoregulation and dpp-mediated inhibition of wg expression are required for the coordinated regulation of furrow initiation and progression. Finally, we show that in the later stages of retinal differentiation, reduction of dpp function leads to an arrest in MF progression.

scholarly journals Ectopic expression of the Stabilin2 gene triggered by an intracisternal A particle (IAP) element in DBA/2J strain of mice

2020 ◽  
Vol 31 (1-2) ◽  
pp. 2-16 ◽  
Author(s):  
Nobuyo Maeda-Smithies ◽  
Sylvia Hiller ◽  
Sharlene Dong ◽  
Hyung-Suk Kim ◽  
Brian J. Bennett ◽  
...  
Keyword(s):  
Promoter Region ◽  
Transmembrane Protein ◽  
Scavenger Receptor ◽  
Ectopic Expression ◽  
Complete Suppression ◽  
Liver Sinusoidal Endothelial Cells ◽  
Normal Expression ◽  
Number Of Genes ◽  
Genes Encoding ◽  
Intracisternal A Particle

AbstractStabilin2 (Stab2) encodes a large transmembrane protein which is predominantly expressed in the liver sinusoidal endothelial cells (LSECs) and functions as a scavenger receptor for various macromolecules including hyaluronans (HA). In DBA/2J mice, plasma HA concentration is ten times higher than in 129S6 or C57BL/6J mice, and this phenotype is genetically linked to the Stab2 locus. Stab2 mRNA in the LSECs was significantly lower in DBA/2J than in 129S6, leading to reduced STAB2 proteins in the DBA/2J LSECs. We found a retrovirus-derived transposable element, intracisternal A particle (IAP), in the promoter region of Stab2DBA which likely interferes with normal expression in the LSECs. In contrast, in other tissues of DBA/2J mice, the IAP drives high ectopic Stab2DBA transcription starting within the 5′ long terminal repeat of IAP in a reverse orientation and continuing through the downstream Stab2DBA. Ectopic transcription requires the Stab2-IAP element but is dominantly suppressed by the presence of loci on 59.7–73.0 Mb of chromosome (Chr) 13 from C57BL/6J, while the same region in 129S6 requires additional loci for complete suppression. Chr13:59.9–73 Mb contains a large number of genes encoding Krüppel-associated box-domain zinc-finger proteins that target transposable elements-derived sequences and repress their expression. Despite the high amount of ectopic Stab2DBA transcript in tissues other than liver, STAB2 protein was undetectable and unlikely to contribute to the plasma HA levels of DBA/2J mice. Nevertheless, the IAP insertion and its effects on the transcription of the downstream Stab2DBA exemplify that stochastic evolutional events could significantly influence susceptibility to complex but common diseases.

scholarly journals Characterization of the Overlapping Promoters of nolB and nolW, Two Soybean Cultivar Specificity Genes from Rhizobium fredii Strain USDA257

1997 ◽  
Vol 10 (1) ◽  
pp. 138-141 ◽  
Author(s):  
Jun Gu ◽  
Pedro A. Balatti ◽  
Hari B. Krishnan ◽  
Steven G. Pueppke
Keyword(s):  
Regulatory Gene ◽  
Initiation Site ◽  
Dual Control ◽  
Start Site ◽  
Rhizobium Fredii ◽  
Normal Expression ◽  
Transcript Initiation ◽  
Cultivar Specificity ◽  
Transcript Start Site

The transcripts of nolW and nolB, two divergently oriented cultivar specificity genes of Rhizobium fredii strain USDA257, are known to be initiated 14 bp apart from promoters that face one another. We show here that expression of nolB is dependent both on induction with flavonoid signals and on the regulatory gene, nodD1. Expression of nolW is constitutive and independent of flavonoids and nodD1. Normal expression of nolB is retained with a promoter that extends only 61 bp upstream of the transcript start site, but it is lost if an additional 24 bp are removed. Substantial expression of nolW is retained with a promoter that contains only 34 bp of DNA upstream from the transcript initiation site. The dual control region for the two genes is thus only about 109 bp in length.

Misexpression of chick Vg1 in the marginal zone induces primitive streak formation

Development ◽  
1997 ◽  
Vol 124 (24) ◽  
pp. 5127-5138 ◽  
Author(s):  
S.B. Shah ◽  
I. Skromne ◽  
C.R. Hume ◽  
D.S. Kessler ◽  
K.J. Lee ◽  
...  
Keyword(s):  
Marginal Zone ◽  
Ectopic Expression ◽  
Primitive Streak ◽  
Axis Formation ◽  
Mesoderm Induction ◽  
Cell Fates ◽  
Signalling Molecules ◽  
Posterior Area ◽  
Area Pellucida

In the chick embryo, the primitive streak is the first axial structure to develop. The initiation of primitive streak formation in the posterior area pellucida is influenced by the adjacent posterior marginal zone (PMZ). We show here that chick Vg1 (cVg1), a member of the TGFbeta family of signalling molecules whose homolog in Xenopus is implicated in mesoderm induction, is expressed in the PMZ of prestreak embryos. Ectopic expression of cVg1 protein in the marginal zone chick blastoderms directs the formation of a secondary primitive streak, which subsequently develops into an ectopic embryo. We have used cell marking techniques to show that cells that contribute to the ectopic primitive streak change fate, acquiring two distinct properties of primitive streak cells, defined by gene expression and cell movements. Furthermore, naive epiblast explants exposed to cVg1 protein in vitro acquire axial mesodermal properties. Together, these results show that cVg1 can mediate ectopic axis formation in the chick by inducing new cell fates and they permit the analysis of distinct events that occur during primitive streak formation.

scholarly journals Needs and Targets for the multi sex combs Gene Product in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1823-1838 ◽  
Author(s):  
Olivier Saget ◽  
Françoise Forquignon ◽  
Pedro Santamaria ◽  
Neel B Randsholt
Keyword(s):  
Drosophila Melanogaster ◽  
Ectopic Expression ◽  
Polycomb Group ◽  
Homeotic Genes ◽  
Maternal Control ◽  
Gap Gene ◽  
Sex Combs ◽  
Normal Expression ◽  
Selector Genes ◽  
Mutant Phenotypes

Abstract We have analyzed the requirements for the multi sex combs (mxc) gene during development to gain further insight into the mechanisms and developmental processes that depend on the important trans-regulators forming the Polycomb group (PcG) in Drosophila melanogaster. mxc is allelic with the tumor suppressor locus lethal (1) malignant blood neoplasm (l(1)mbn). We show that the mxc product is dramatically needed in most tissues because its loss leads to cell death after a few divisions. mxc has also a strong maternal effect. We find that hypomorphic mxc mutations enhance other PcG gene mutant phenotypes and cause ectopic expression of homeotic genes, confirming that PcG products are cooperatively involved in repression of selector genes outside their normal expression domains. We also demonstrate that the mxc product is needed for imaginal head specification, through regulation of the ANT-C gene Deformed. Our analysis reveals that mxc is involved in the maternal control of early zygotic gap gene expression previously reported for some PcG genes and suggests that the mechanism of this early PcG function could be different from the PcG-mediated regulation of homeotic selector genes later in development. We discuss these data in view of the numerous functions of PcG genes during development.

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