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.

frizzled regulates mirror-symmetric pattern formation in the Drosophila eye

Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 3045-3055 ◽  
Author(s):  
L. Zheng ◽  
J. Zhang ◽  
R.W. Carthew
Keyword(s):  
Pattern Formation ◽  
Cell Surface ◽  
Transmembrane Protein ◽  
Photoreceptor Cells ◽  
Mirror Image ◽  
Morphogenetic Furrow ◽  
Symmetric Pattern ◽  
Mosaic Analysis ◽  
Drosophila Eye ◽  
A Cell

Coordinated morphogenesis of ommatidia during Drosophila eye development establishes a mirror-image symmetric pattern across the entire eye bisected by an anteroposterior equator. We have investigated the mechanisms by which this pattern formation occurs and our results suggest that morphogenesis is coordinated by a graded signal transmitted bidirectionally from the presumptive equator to the dorsal and ventral poles. This signal is mediated by frizzled, which encodes a cell surface transmembrane protein. Mosaic analysis indicates that frizzled acts non-autonomously in an equatorial to polar direction. It also indicates that relative levels of frizzled in photoreceptor cells R3 and R4 of each ommatidium affect their positional fate choices such that the cell with greater frizzled activity becomes an R3 cell and the cell with less frizzled activity becomes an R4 cell. Moreover, this bias affects the choice an ommatidium makes as to which direction to rotate. Equator-outwards progression of elav expression and expression of the nemo gene in the morphogenetic furrow are regulated by frizzled, which itself is dynamically expressed about the morphogenetic furrow. We propose that frizzled mediates a bidirectional signal emanating from the equator.

Hedgehog is an indirect regulator of morphogenetic furrow progression in the Drosophila eye disc

Development ◽  
1997 ◽  
Vol 124 (17) ◽  
pp. 3233-3240 ◽  
Author(s):  
D.I. Strutt ◽  
M. Mlodzik
Keyword(s):  
Pattern Formation ◽  
Imaginal Disc ◽  
Morphogenetic Furrow ◽  
Anterior Edge ◽  
Eye Disc ◽  
Drosophila Eye ◽  
Eye Imaginal Disc ◽  
Inductive Signal ◽  
Rate Of Movement

Pattern formation in the eye imaginal disc of Drosophila occurs in a wave that moves from posterior to anterior. The anterior edge of this wave is marked by a contracted band of cells known as the morphogenetic furrow, behind which photoreceptors differentiate. The movement of the furrow is dependent upon the secretion of the signalling protein Hedgehog (Hh) by more posterior cells, and it has been suggested that Hh acts as an inductive signal to induce cells to enter a furrow fate and begin differentiation. To further define the role of Hh in this process, we have analysed clones of cells lacking the function of the smoothened (smo) gene, which is required for transduction of the Hh signal and allows the investigation of the autonomous requirement for hh signalling. These experiments demonstrate that the function of hh in furrow progression is indirect. Cells that cannot receive/transduce the Hh signal are still capable of entering a furrow fate and differentiating normally. However, hh is required to promote furrow progression and regulate its rate of movement across the disc, since the furrow is significantly delayed in smo clones.

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

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.

Shortsighted acts in the decapentaplegic pathway in Drosophila eye development and has homology to a mouse TGF-beta-responsive gene

Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 2835-2845 ◽  
Author(s):  
J.E. Treisman ◽  
Z.C. Lai ◽  
G.M. Rubin
Keyword(s):  
Leucine Zipper ◽  
Optic Lobe ◽  
Tgf Beta ◽  
Morphogenetic Furrow ◽  
Differentiated Cells ◽  
Drosophila Eye ◽  
Undifferentiated Cells ◽  
Leucine Zipper Protein ◽  
Eye Imaginal Disc ◽  
The Brain

Differentiation in the Drosophila eye imaginal disc traverses the disc as a wave moving from posterior to anterior. The propagation of this wave is driven by hedgehog protein secreted by the differentiated cells in the posterior region of the disc. Hedgehog induces decapentaplegic expression at the front of differentiation, in the morphogenetic furrow. We have identified a gene, shortsighted, which is expressed in a hedgehog-dependent stripe in the undifferentiated cells just anterior to the furrow and which appears to be involved in the transmission of the differentiation-inducing signal; a reduction in shortsighted function leads to a delay in differentiation and to a loss of photoreceptors in the adult. shortsighted is also required for a morphogenetic movement in the brain that reorients the second optic lobe relative to the first. shortsighted encodes a cytoplasmic leucine zipper protein with homology to a mouse gene, TSC-22, which is transcriptionally induced in response to TGF-beta.

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.

Characterization of Star and its interactions with sevenless and EGF receptor during photoreceptor cell development in Drosophila

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 1731-1745 ◽  
Author(s):  
A.L. Kolodkin ◽  
A.T. Pickup ◽  
D.M. Lin ◽  
C.S. Goodman ◽  
U. Banerjee
Keyword(s):  
Genetic Background ◽  
Egf Receptor ◽  
Transmembrane Domain ◽  
Loss Of Function ◽  
Morphogenetic Furrow ◽  
Eye Disc ◽  
Son Of Sevenless ◽  
Photoreceptor Development ◽  
Star Gene

Loss-of-function mutations in Star impart a dominant rough eye phenotype and, when homozygous, are embryonic lethal with ventrolateral cuticular defects. We have cloned the Star gene and show that it encodes a novel protein with a putative transmembrane domain. Star transcript is expressed in a dynamic pattern in the embryo including in cells of the ventral midline. In the larval eye disc, Star is expressed first at the morphogenetic furrow, then in the developing R2, R5, and R8 cells as well as in the posterior clusters of the disc in additional R cells. Star interacts with Drosophila EGF receptor in the eye and mosaic analysis of Star in the larval eye disc reveals that homozygous Star patches contain no developing R cells. Taken together with the expression pattern at the morphogenetic furrow, these results demonstrate an early role for Star in photoreceptor development. Additionally, loss-of-function mutations in Star act as suppressors of R7 development in a sensitized genetic background involving the Son of sevenless (Sos) locus, and overexpression of Star enhances R7 development in this genetic background. Based on the genetic interactions with Sos, we suggest that Star also has a later role in photoreceptor development including the recruitment of the R7 cell through the sevenless pathway.

Progression of the morphogenetic furrow in the Drosophila eye: the roles of Hedgehog, Decapentaplegic and the Raf pathway

Development ◽  
1999 ◽  
Vol 126 (24) ◽  
pp. 5795-5808 ◽  
Author(s):  
S. Greenwood ◽  
G. Struhl
Keyword(s):  
Transcription Factor ◽  
Short Range ◽  
Morphogenetic Furrow ◽  
Serine Threonine Kinase ◽  
Present Evidence ◽  
Threonine Kinase ◽  
Drosophila Eye ◽  
Undifferentiated Cells ◽  
Hh Signaling ◽  
Necessary And Sufficient

During Drosophila eye development, Hedgehog (Hh) protein secreted by maturing photoreceptors directs a wave of differentiation that sweeps anteriorly across the retinal primordium. The crest of this wave is marked by the morphogenetic furrow, a visible indentation that demarcates the boundary between developing photoreceptors located posteriorly and undifferentiated cells located anteriorly. Here, we present evidence that Hh controls progression of the furrow by inducing the expression of two downstream signals. The first signal, Decapentaplegic (Dpp), acts at long range on undifferentiated cells anterior to the furrow, causing them to enter a ‘pre-proneural’ state marked by upregulated expression of the transcription factor Hairy. Acquisition of the pre-proneural state appears essential for all prospective retinal cells to enter the proneural pathway and differentiate as photoreceptors. The second signal, presently unknown, acts at short range and is transduced via activation of the Serine-Threonine kinase Raf. Activation of Raf is both necessary and sufficient to cause pre-proneural cells to become proneural, a transition marked by downregulation of Hairy and upregulation of the proneural activator, Atonal (Ato), which initiates differentiation of the R8 photoreceptor. The R8 photoreceptor then organizes the recruitment of the remaining photoreceptors (R1-R7) through additional rounds of Raf activation in neighboring pre-proneural cells. Finally, we show that Dpp signaling is not essential for establishing either the pre-proneural or proneural states, or for progression of the furrow. Instead, Dpp signaling appears to increase the rate of furrow progression by accelerating the transition to the pre-proneural state. In the abnormal situation in which Dpp signaling is blocked, Hh signaling can induce undifferentiated cells to become pre-proneural but does so less efficiently than Dpp, resulting in a retarded rate of furrow progression and the formation of a rudimentary eye.

scholarly journals Ectopic expression of human p53 inhibits entry into S phase and induces apoptosis in the Drosophila eye imaginal disc

Oncogene ◽  
1999 ◽  
Vol 18 (48) ◽  
pp. 6767-6775 ◽  
Author(s):  
Masamitsu Yamaguchi ◽  
Fumiko Hirose ◽  
Yoshihiro H Inoue ◽  
Michina Shiraki ◽  
Yuko Hayashi ◽  
...  
Keyword(s):  
Imaginal Disc ◽  
Ectopic Expression ◽  
S Phase ◽  
Drosophila Eye ◽  
Eye Imaginal Disc
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