scholarly journals Control of cell fate and polarity in the adult abdominal segments of Drosophila by optomotor-blind

Development ◽  
1997 ◽  
Vol 124 (19) ◽  
pp. 3715-3726 ◽  
Author(s):  
A. Kopp ◽  
I. Duncan
Keyword(s):  
Cell Fate ◽  
Anterior Part ◽  
Ectopic Expression ◽  
Mirror Image ◽  
Posterior Compartment ◽  
Anterior Portion ◽  
Posterior Portion ◽  
Anterior Compartment ◽  
Compartment Boundary ◽  
Hh Signaling

In an accompanying report (Kopp, A., Muskavitch, M. A. T. and Duncan, I. (1997) Development 124, 3703–3714), we show that Hh protein secreted by posterior compartment cells patterns the posterior portion of the anterior compartment in adult abdominal segments. Here we show that this function of hh is mediated by optomotor-blind (omb). omb- mutants mimic the effects of loss-of-function alleles of hh: structures from the posterior of the anterior compartment are lost, and often this region develops as a mirror image of the anterior portion. Structures from the anterior part of the posterior compartment are also lost. In the pupa, omb expression in abdominal histoblasts is highest at or near the compartment boundary, and decreases in a shallow gradient toward the anterior. This gradient is due to activation of omb by Hh secreted by posterior compartment cells. In contrast to imaginal discs, this Hh signaling is not mediated by dpp or wg. We describe several gain-of-function alleles that cause ectopic expression of omb in the anterior of the segment. Most of these cause the anterior region to develop with posterior characteristics without affecting polarity. However, an allele that drives high level ubiquitous expression of omb (QdFab) causes the anterior tergite to develop as a mirror-image duplication of the posterior tergite, a pattern opposite to that seen in omb- mutants. Ubiquitous expression of hh causes similar double-posterior patterning. We find that omb- alleles suppress this effect of ectopic hh expression and that posterior patterning becomes independent of hh in the QdFab mutant. These observations indicate that omb is the primary target of hh signaling in the adult abdomen. However, it is clear that other targets exist. One of these is likely Scruffy, a novel gene that we describe, which acts in parallel to omb. To explain the effects of omb alleles, we propose that both anterior and posterior compartments in the abdomen are polarized by underlying symmetric gradients of unknown origin. We suggest that omb has two functions. First, it specifies the development of appropriate structures both anterior and posterior to the compartment boundary. Second, it causes cells to reverse their interpretation of polarity specified by the underlying symmetric gradients.

The roles of hedgehog and engrailed in patterning adult abdominal segments of Drosophila

Development ◽  
1997 ◽  
Vol 124 (19) ◽  
pp. 3703-3714 ◽  
Author(s):  
A. Kopp ◽  
M.A. Muskavitch ◽  
I. Duncan
Keyword(s):  
Ectopic Expression ◽  
Restrictive Temperature ◽  
Primary Role ◽  
Loss Of Function ◽  
Posterior Compartment ◽  
Anterior Portion ◽  
Posterior Portion ◽  
Anterior Compartment ◽  
Present Evidence ◽  
Anterior Patterning

We present evidence that hedgehog (hh) protein secreted by posterior compartment cells plays a key role in patterning the posterior portion of the anterior compartment in adult abdominal segments. Loss of function of hh in the hh(ts2) mutant causes the loss of posterior tergite characteristics in the anterior compartment, whereas ectopic expression driven by hs-hh or the gain-of-function allele hh(Mir) causes transformation of anterior structures toward the posterior. FLP-out hh-expressing clones in the anterior compartment induce surrounding wild-type cells to produce posterior tergite structures, establishing that hh functions nonautonomously. The effects of pulses of ectopic expression driven by hs-hh indicate that bristle type and pigmentation are patterned by hh at widely different times in pupal development. We also present evidence that the primary polarization of abdominal segments is symmetric. This symmetry is strikingly revealed by ectopic expression of engrailed (en). As expected, this transforms anterior compartment cells to posterior compartment identity. In addition, however, ectopic en expression causes an autonomous reversal of polarity in the anterior portion of the anterior compartment, but not the posterior portion. By determining the position of polarity reversal within en-expressing clones, we were able to define a cryptic line of symmetry that lies within the pigment band of the normal tergite. This line appears to be retained in hh(ts2) mutants raised at the restrictive temperature, suggesting it is not established by hh signaling. We argue that the primary role of hh in controlling polarity is to cause anterior compartment cells to reverse their interpretation of an underlying symmetric polarization. Consistent with this, we find that strong ectopic expression of hh causes mirror-symmetric double posterior patterning, whereas hh loss of function can cause mirror-symmetric double anterior patterning.

Signaling through both type I DPP receptors is required for anterior-posterior patterning of the entire Drosophila wing

Development ◽  
1997 ◽  
Vol 124 (1) ◽  
pp. 79-89 ◽  
Author(s):  
M.A. Singer ◽  
A. Penton ◽  
V. Twombly ◽  
F.M. Hoffmann ◽  
W.M. Gelbart
Keyword(s):  
Cell Fate ◽  
Type I ◽  
Posterior Compartment ◽  
Anterior Compartment ◽  
Hypomorphic Allele ◽  
Compartment Boundary ◽  
Adult Wing ◽  
Mutant Cells ◽  
Narrow Stripe ◽  
Anterior Posterior

The imaginal disk expression of the TGF-beta superfamily member DPP in a narrow stripe of cells along the anterior-posterior compartment boundary is essential for proper growth and patterning of the Drosophila appendages. We examine DPP receptor function to understand how this localized DPP expression produces its global effects upon appendage development. Clones of saxophone (sax) or thick veins (tkv) mutant cells, defective in one of the two type I receptors for DPP, show shifts in cell fate along the anterior-posterior axis. In the adult wing, clones that are homozygous for a null allele of sax or a hypomorphic allele of tkv show shifts to more anterior fates when the clone is in the anterior compartment and to more posterior fates when the clone is in the posterior compartment. The effect of these clones upon the expression pattern of the downstream gene spalt-major also correlates with these specific shifts in cell fate. The similar effects of sax null and tkv hypomorphic clones indicate that the primary difference in the function of these two receptors during wing patterning is that TKV transmits more of the DPP signal than does SAX. Our results are consistent with a model in which a gradient of DPP reaches all cells in the developing wing blade to direct anterior-posterior pattern.

Positional signaling by hedgehog in Drosophila imaginal disc development

Development ◽  
1995 ◽  
Vol 121 (1) ◽  
pp. 1-10 ◽  
Author(s):  
A.L. Felsenfeld ◽  
J.A. Kennison
Keyword(s):  
Hedgehog Signaling ◽  
Imaginal Disc ◽  
Ectopic Expression ◽  
Posterior Compartment ◽  
Anterior Compartment ◽  
Segment Polarity ◽  
Wing Structures ◽  
Wing Discs ◽  
Segment Polarity Gene ◽  
Polarity Gene

We describe a dominant gain-of-function allele of the segment polarity gene hedgehog. This mutation causes ectopic expression of hedgehog mRNA in the anterior compartment of wing discs, leading to overgrowth of tissue in the anterior of the wing and partial duplication of distal wing structures. The posterior compartment of the wing is unaffected. Other imaginal derivatives are affected, resulting in duplications of legs and antennae and malformations of eyes. In mutant imaginal wing discs, expression of the decapentaplegic gene, which is implicated in the hedgehog signaling pathway, is also perturbed. The results suggest that hedgehog protein acts in the wing as a signal to instruct neighboring cells to adopt fates appropriate to the region of the wing just anterior to the compartmental boundary.

Role of knot (kn) in Wing Patterning in Drosophila

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1203-1212 ◽  
Author(s):  
Katerina Nestoras ◽  
Helena Lee ◽  
Jym Mohler
Keyword(s):  
Hedgehog Signaling ◽  
Imaginal Disc ◽  
Hedgehog Signaling Pathway ◽  
Posterior Compartment ◽  
Drosophila Wing ◽  
Compartment Boundary ◽  
Hh Signaling ◽  
Embryonic Segmentation ◽  
Anterior Posterior

We have undertaken a genetic analysis of new strong alleles of knot (kn). The original kn1 mutation causes an alteration of wing patterning similar to that associated with mutations of fused (fu), an apparent fusion of veins 3 and 4 in the wing. However, unlike fu, strong kn mutations do not affect embryonic segmentation and indicate that kn is not a component of a general Hh (Hedgehog)-signaling pathway. Instead we find that kn has a specific role in those cells of the wing imaginal disc that are subject to ptc-mediated Hh-signaling. Our results suggest a model for patterning the medial portion of the Drosophila wing, whereby the separation of veins 3 and 4 is maintained by kn activation in the intervening region in response to Hh-signaling across the adjacent anterior-posterior compartment boundary.

engrailed and polyhomeotic interactions are required to maintain the A/P boundary of the Drosophila developing wing

Development ◽  
1998 ◽  
Vol 125 (15) ◽  
pp. 2771-2780 ◽  
Author(s):  
F. Maschat ◽  
N. Serrano ◽  
N.B. Randsholt ◽  
G. Geraud
Keyword(s):  
Cell Fate ◽  
Regulatory Protein ◽  
Polycomb Group ◽  
Posterior Compartment ◽  
Cubitus Interruptus ◽  
Anterior Compartment ◽  
Embryonic Segmentation ◽  
Wing Morphogenesis ◽  
Anterior Posterior

Engrailed is a nuclear regulatory protein with essential roles in embryonic segmentation and wing morphogenesis. One of its regulatory targets in embryos was shown to be the Polycomb group gene, polyhomeotic. We show here that transheterozygous adult flies, mutant for both engrailed and polyhomeotic, show a gap in the fourth vein. In the corresponding larval imaginal discs, a polyhomeotic-lacZ enhancer trap is not normally activated in anterior cells adjacent to the anterior-posterior boundary. This intermediary region corresponds to the domain of low engrailed expression that appears in the anterior compartment, during L3. Several arguments show that engrailed is responsible for the induction of polyhomeotic in these cells. The role of polyhomeotic in this intermediary region is apparently to maintain the repression of hedgehog in the anterior cells abutting the anterior-posterior boundary, since these cells ectopically express hedgehog when polyhomeotic is not activated. This leads to ectopic expressions first of patched, then of cubitus interruptus and decapentaplegic in the posterior compartment, except for the dorsoventral border cells that are not affected. Thus posterior cells express a new set of genes that are normally characteristic of anterior cells, suggesting a change in the cell identity. Altogether, our data indicate that engrailed and polyhomeotic interactions are required to maintain the anterior-posterior boundary and the posterior cell fate, just prior to the evagination of the wing.

Activation of Fgf-4 and HoxD gene expression by BMP-2 expressing cells in the developing chick limb

Development ◽  
1996 ◽  
Vol 122 (6) ◽  
pp. 1821-1828 ◽  
Author(s):  
D.M. Duprez ◽  
K. Kostakopoulou ◽  
P.H. Francis-West ◽  
C. Tickle ◽  
P.M. Brickell
Keyword(s):  
Gene Expression ◽  
Anterior Part ◽  
Ectopic Expression ◽  
Mirror Image ◽  
Limb Bud ◽  
Bone Morphogenetic Protein 2 ◽  
Morphogenetic Protein ◽  
Wing Bud ◽  
Hoxd Gene

Bone morphogenetic protein-2 (BMP-2) has been implicated in the polarizing region signalling pathway, which specifies pattern across the antero-posterior of the developing vertebrate limb. Retinoic acid and Sonic Hedgehog (SHH) can act as polarizing signals; when applied anteriorly in the limb bud, they induce mirror-image digit duplications and ectopic Bmp-2 expression in anterior mesenchyme. In addition, the two signals can activate Fgf-4 expression in anterior ridge and HoxD expression in anterior mesenchyme. We tested the role of BMP-2 in this signalling cascade by ectopically expressing human BMP-2 (hBMP-2) at the anterior margin of the early wing bud using a replication defective retroviral vector, and found that ectopic expression of Fgf-4 was induced in the anterior part of the apical ectodermal ridge, followed later by ectopic expression of Hoxd-11 and Hoxd-13 in anterior mesenchyme. This suggests that BMP-2 is involved in regulating Fgf-4 and HoxD gene expression in the normal limb bud. Ectopically expressed hBMP-2 also induced duplication of digit 2 and bifurcation of digit 3, but could not produce the mirror-image digit duplications obtained with SHH-expressing cells. These results suggest that BMP-2 may be involved primarily in maintenance of the ridge, and in the link between patterning and outgrowth of the limb bud.

scholarly journals Effect of abx, bx and pbx mutations on expression of homeotic genes in Drosophila larvae.

Genetics ◽  
1990 ◽  
Vol 124 (4) ◽  
pp. 899-908 ◽  
Author(s):  
J W Little ◽  
C A Byrd ◽  
D L Brower
Keyword(s):  
Ectopic Expression ◽  
Wing Disc ◽  
Homeotic Genes ◽  
Wild Type ◽  
Posterior Compartment ◽  
Altered Expression ◽  
Anterior Compartment ◽  
Regulatory Domains ◽  
Wild Type Phenotype ◽  
Drosophila Larvae

Abstract We have examined the patterns of expression of the homeotic gene Ubx in imaginal discs of Drosophila larvae carrying mutations in the abx, bx and pbx regulatory domains. In haltere discs, all five bx insertion mutations examined led to a general reduction in Ubx expression in the anterior compartment; for a given allele, the strength of the adult cuticle phenotype correlated with the degree of Ubx reduction. Deletions mapping near or overlapping the sites of bx insertions, including three abx alleles and the bx34e-prv(bx-prv) allele, showed greatly reduced Ubx expression in parts of the anterior compartment of the haltere disc; however, anterior patches of strong Ubx expression often remained, in highly variable patterns. As expected, the pbx1 mutation led to reduced Ubx expression in the posterior compartment of the haltere disc; surprisingly, pbx1 also led to altered expression of the en protein near the compartment border in the central region of the disc. In the metathoracic leg, all the bx alleles caused extreme reduction in Ubx expression in the anterior regions, with no allele-specific differences. In contrast, abx and bx-prv alleles resulted in patchy anterior reductions in third leg discs. In the larval central nervous system, abx but not bx alleles affected Ubx expression; the bx-prv deletion gave a wild-type phenotype, but it could not fully complement abx mutations. In the posterior wing disc, the bx-prv allele, and to a much lesser extent the bx34e chromosome from which it arose, led to ectopic expression of Ubx. Unlike other grain-of-function mutations in the BX-C, this phenotype appeared to be partially recessive to wild type. Finally, we asked whether the ppx transformation, which results from early lack of Ubx+ function in the mesothorax and is seen in abx animals, is due to ectopic Scr expression. Some mesothoracic leg and wing discs from abx2 larvae displayed ectopic expression of Scr, which was variable in extent but always confined to the posterior compartment.

scholarly journals CtBP impedes JNK- and Upd/STAT-driven cell fate misspecifications in regenerating Drosophila imaginal discs

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Melanie I Worley ◽  
Larissa A Alexander ◽  
Iswar K Hariharan
Keyword(s):  
Cell Fate ◽  
Tissue Damage ◽  
Binding Protein ◽  
Ectopic Expression ◽  
Cell Types ◽  
Imaginal Discs ◽  
Cell Fates ◽  
Genetic Ablation ◽  
Compartment Boundary ◽  
Wing Pouch

Regeneration following tissue damage often necessitates a mechanism for cellular re-programming, so that surviving cells can give rise to all cell types originally found in the damaged tissue. This process, if unchecked, can also generate cell types that are inappropriate for a given location. We conducted a screen for genes that negatively regulate the frequency of notum-to-wing transformations following genetic ablation and regeneration of the wing pouch, from which we identified mutations in the transcriptional co-repressor C-terminal Binding Protein (CtBP). When CtBP function is reduced, ablation of the pouch can activate the JNK/AP-1 and JAK/STAT pathways in the notum to destabilize cell fates. Ectopic expression of Wingless and Dilp8 precede the formation of the ectopic pouch, which is subsequently generated by recruitment of both anterior and posterior cells near the compartment boundary. Thus, CtBP stabilizes cell fates following damage by opposing the destabilizing effects of the JNK/AP-1 and JAK/STAT pathways.

scholarly journals Membrane potential regulates Hedgehog signaling and compartment boundary maintenance in the Drosophila wing disc

2020 ◽  
Author(s):  
Maya Emmons-Bell ◽  
Riku Yasutomi ◽  
Iswar K. Hariharan
Keyword(s):  
Membrane Potential ◽  
Hedgehog Signaling ◽  
Membrane Depolarization ◽  
Wing Disc ◽  
Anterior Compartment ◽  
Drosophila Wing ◽  
Compartment Boundary ◽  
Boundary Maintenance ◽  
Elevated Expression ◽  
Hh Signaling

AbstractThe Drosophila wing imaginal disc is composed of two lineage-restricted populations of cells separated by a smooth boundary. Hedgehog (Hh) from posterior cells activates a signaling pathway in anterior cells near the boundary which is necessary for boundary maintenance. Here, we show that membrane potential is patterned in the wing disc. Anterior cells near the boundary, where Hh signaling is most active, are more depolarized than posterior cells across the boundary. Elevated expression of the ENaC channel Ripped Pocket (Rpk), observed in these anterior cells, requires Hh. Antagonizing Rpk reduces depolarization and disrupts the compartment boundary. Using genetic and optogenetic manipulations, we show that membrane depolarization promotes membrane localization of Smoothened and augments Hh signaling. Thus, membrane depolarization and Hh-dependent signaling mutually reinforce each other in this region. Finally, clones of depolarized cells survive preferentially in the anterior compartment and clones of hyperpolarized cells survive preferentially in the posterior compartment.

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