Molecular characterisation of the Polycomblike gene of Drosophila melanogaster, a trans-acting negative regulator of homeotic gene expression

The Polycomblike gene of Drosophila melanogaster, a member of the Polycomb Group of genes, is required for the correct spatial expression of the homeotic genes of the Antennapaedia and Bithorax Complexes. Mutations in Polycomb Group genes result in ectopic homeotic gene expression, indicating that Polycomb Group proteins maintain the transcriptional repression of specific homeotic genes in specific tissues during development. We report here the isolation and molecular characterisation of the Polycomblike gene. The Polycomblike transcript encodes an 857 amino acid protein with no significant homology to other proteins. Antibodies raised against the product of this open reading frame were used to show that the Polycomblike protein is found in all nuclei during embryonic development. Antibody staining also revealed that the Polycomblike protein is found on larval salivary gland polytene chromosomes at about 100 specific loci, the same loci to which the Polycomb and polyhomeotic proteins, two other Polycomb Group proteins, are found. These data add further support for a model in which Polycomb Group proteins form multimeric protein complexes at specific chromosomal loci to repress transcription at those loci.

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Transvection and Silencing of the Scr Homeotic Gene of Drosophila melanogaster

Genetics ◽

10.1093/genetics/161.2.733 ◽

2002 ◽

Vol 161 (2) ◽

pp. 733-746

Author(s):

Jeffrey W Southworth ◽

James A Kennison

Keyword(s):

Drosophila Melanogaster ◽

Chromosomal Aberrations ◽

Regulatory Element ◽

Regulatory Elements ◽

Anomalous Behavior ◽

Polycomb Group ◽

Homeotic Gene ◽

Polycomb Group Proteins ◽

Sex Combs Reduced ◽

In Cis

Abstract The Sex combs reduced (Scr) gene specifies the identities of the labial and first thoracic segments in Drosophila melanogaster. In imaginal cells, some Scr mutations allow cis-regulatory elements on one chromosome to stimulate expression of the promoter on the homolog, a phenomenon that was named transvection by Ed Lewis in 1954. Transvection at the Scr gene is blocked by rearrangements that disrupt pairing, but is zeste independent. Silencing of the Scr gene in the second and third thoracic segments, which requires the Polycomb group proteins, is disrupted by most chromosomal aberrations within the Scr gene. Some chromosomal aberrations completely derepress Scr even in the presence of normal levels of all Polycomb group proteins. On the basis of the pattern of chromosomal aberrations that disrupt Scr gene silencing, we propose a model in which two cis-regulatory elements interact to stabilize silencing of any promoter or cis-regulatory element physically between them. This model also explains the anomalous behavior of the Scx allele of the flanking homeotic gene, Antennapedia. This allele, which is associated with an insertion near the Antennapedia P1 promoter, inactivates the Antennapedia P1 and P2 promoters in cis and derepresses the Scr promoters both in cis and on the homologous chromosome.

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Genetic interactions and dosage effects of Polycomb group genes in mice

Development ◽

10.1242/dev.125.18.3543 ◽

1998 ◽

Vol 125 (18) ◽

pp. 3543-3551 ◽

Cited By ~ 5

Author(s):

S. Bel ◽

N. Core ◽

M. Djabali ◽

K. Kieboom ◽

N. Van der Lugt ◽

...

Keyword(s):

Hox Genes ◽

Expression Patterns ◽

Axial Skeleton ◽

Polycomb Group ◽

Genetic Interactions ◽

Homeotic Gene ◽

Polycomb Group Genes ◽

Dosage Effects ◽

Somitic Mesoderm ◽

Homeotic Gene Expression

In Drosophila and mouse, Polycomb group genes are involved in the maintenance of homeotic gene expression patterns throughout development. Here we report the skeletal phenotypes of compound mutants for two Polycomb group genes bmi1 and M33. We show that mice deficient for both bmi1 and M33 present stronger homeotic transformations of the axial skeleton as compared to each single Polycomb group mutant, indicating strong dosage interactions between those two genes. These skeletal transformations are accompanied with an enhanced shift of the anterior limit of expression of several Hox genes in the somitic mesoderm. Our results demonstrate that in mice the Polycomb group genes act in synergy to control the nested expression pattern of some Hox genes in somitic mesodermal tissues during development.

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Trithorax regulates multiple homeotic genes in the bithorax and Antennapedia complexes and exerts different tissue-specific, parasegment-specific and promoter-specific effects on each

Development ◽

10.1242/dev.117.1.119 ◽

1993 ◽

Vol 117 (1) ◽

pp. 119-134 ◽

Cited By ~ 16

Author(s):

T.R. Breen ◽

P.J. Harte

Keyword(s):

Gene Expression ◽

Expression Patterns ◽

The Body ◽

Homeotic Gene ◽

Homeotic Genes ◽

Sex Combs Reduced ◽

Tissue Specific ◽

Specific Effects ◽

Normal Expression ◽

Homeotic Gene Expression

The trithorax (trx) gene is required for normal development of the body plan in Drosophila embryos and adults. Mutations in trx cause homeotic transformations throughout the body. Genetic studies suggest that trx encodes a positive regulatory factor required throughout development for normal expression of multiple homeotic genes of the bithorax and Antennapedia complexes (BX-C and ANT-C). To determine how trx influences homeotic gene expression, we examined the expression of the BX-C genes Ultrabithorax, abdominal-A, Abdominal-B and the ANT-C genes Antennapedia, Sex combs reduced and Deformed in trx embryos. We show that trx does indeed exert its effects by positively regulating homeotic gene expression and that its effects on expression of individual homeotic genes are complex: each of the BX-C and ANT-C genes examined exhibits different tissue-specific, parasegment-specific and promoter-specific reductions in their expression. This implies that each of these genes have different requirements for trx in different spatial contexts in order to achieve normal expression levels, presumably depending on the promoters involved and the other regulatory factors bound at each of their multiple tissue- and parasegment-specific cis-regulatory sites in different regions of the embryo. These results also imply that those components of homeotic gene expression patterns for which trx is dispensable, require other factors, possibly those encoded by other trithorax-like genes.

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The Polycomb group in Caenorhabditis elegans and maternal control of germline development

Development ◽

10.1242/dev.125.13.2469 ◽

1998 ◽

Vol 125 (13) ◽

pp. 2469-2478 ◽

Cited By ~ 7

Author(s):

I. Korf ◽

Y. Fan ◽

S. Strome

Keyword(s):

Gene Expression ◽

Caenorhabditis Elegans ◽

Polycomb Group ◽

Polycomb Group Proteins ◽

Polycomb Group Protein ◽

Maternal Control ◽

Germline Development ◽

C Elegans ◽

Polycomb Group Genes ◽

Group Protein

Four Caenorhabditis elegans genes, mes-2, mes-3, mes-4 and mes-6, are essential for normal proliferation and viability of the germline. Mutations in these genes cause a maternal-effect sterile (i.e. mes) or grandchildless phenotype. We report that the mes-6 gene is in an unusual operon, the second example of this type of operon in C. elegans, and encodes the nematode homolog of Extra sex combs, a WD-40 protein in the Polycomb group in Drosophila. mes-2 encodes another Polycomb group protein (see paper by Holdeman, R., Nehrt, S. and Strome, S. (1998). Development 125, 2457–2467). Consistent with the known role of Polycomb group proteins in regulating gene expression, MES-6 is a nuclear protein. It is enriched in the germline of larvae and adults and is present in all nuclei of early embryos. Molecular epistasis results predict that the MES proteins, like Polycomb group proteins in Drosophila, function as a complex to regulate gene expression. Database searches reveal that there are considerably fewer Polycomb group genes in C. elegans than in Drosophila or vertebrates, and our studies suggest that their primary function is in controlling gene expression in the germline and ensuring the survival and proliferation of that tissue.

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Su(z)12, a novelDrosophilaPolycomb group gene that is conserved in vertebrates and plants

Development ◽

10.1242/dev.128.17.3371 ◽

2001 ◽

Vol 128 (17) ◽

pp. 3371-3379 ◽

Cited By ~ 8

Author(s):

Anna Birve ◽

Aditya K. Sengupta ◽

Dirk Beuchle ◽

Jan Larsson ◽

James A. Kennison ◽

...

Keyword(s):

Hox Genes ◽

Position Effect ◽

Polycomb Group ◽

Homeotic Gene ◽

Homeotic Genes ◽

Position Effect Variegation ◽

Regulatory Machinery ◽

Effect Variegation ◽

Arabidopsis Proteins ◽

Homeotic Gene Expression

In both Drosophila and vertebrates, spatially restricted expression of HOX genes is controlled by the Polycomb group (PcG) repressors. Here we characterize a novel Drosophila PcG gene, Suppressor of zeste 12 (Su(z)12). Su(z)12 mutants exhibit very strong homeotic transformations and Su(z)12 function is required throughout development to maintain the repressed state of HOX genes. Unlike most other PcG mutations, Su(z)12 mutations are strong suppressors of position-effect variegation (PEV), suggesting that Su(z)12 also functions in heterochromatin-mediated repression. Furthermore, Su(z)12 function is required for germ cell development. The Su(z)12 protein is highly conserved in vertebrates and is related to the Arabidopsis proteins EMF2, FIS2 and VRN2. Notably, EMF2 is a repressor of floral homeotic genes. These results suggest that at least some of the regulatory machinery that controls homeotic gene expression is conserved between animals and plants.

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The product of the murine homolog of the Drosophila extra sex combs gene displays transcriptional repressor activity.

Molecular and Cellular Biology ◽

10.1128/mcb.17.8.4707 ◽

1997 ◽

Vol 17 (8) ◽

pp. 4707-4717 ◽

Cited By ~ 65

Author(s):

O N Denisenko ◽

K Bomsztyk

Keyword(s):

Gene Expression ◽

Transcriptional Repressor ◽

Point Mutations ◽

Homeotic Gene ◽

Homeotic Genes ◽

Sex Combs ◽

Dna Elements ◽

Nuclear Ribonucleoprotein ◽

Repressor Activity ◽

Homeotic Gene Expression

The heterogeneous nuclear ribonucleoprotein K protein represents a novel class of proteins that may act as docking platforms that orchestrate cross-talk among molecules involved in signal transduction and gene expression. Using a fragment of K protein as bait in the yeast two-hybrid screen, we isolated a cDNA that encodes a protein whose primary structure has extensive similarity to the Drosophila melanogaster extra sex combs (esc) gene product, Esc, a putative silencer of homeotic genes. The cDNA that we isolated is identical to the cDNA of the recently positionally cloned mouse embryonic ectoderm development gene, eed. Like Esc, Eed contains six WD-40 repeats in the C-terminal half of the protein and is thought to repress homeotic gene expression during mouse embryogenesis. Eed binds to K protein through a domain in its N terminus, but interestingly, this domain is not found in the Drosophila Esc. Gal4-Eed fusion protein represses transcription of a reporter gene driven by a promoter that contains Gal4-binding DNA elements. Eed also represses transcription when recruited to a target promoter by Gal4-K protein. Point mutations within the eed gene that are responsible for severe embryonic development abnormalities abolished the transcriptional repressor activity of Eed. Results of this study suggest that Eed-restricted homeotic gene expression during embryogenesis reflects the action of Eed as a transcriptional repressor. The Eed-mediated transcriptional effects are likely to reflect the interaction of Eed with multiple molecular partners, including K protein.

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The Drosophila Polycomb Group proteins ESC and E(Z) bind directly to each other and co-localize at multiple chromosomal sites

Development ◽

10.1242/dev.125.17.3483 ◽

1998 ◽

Vol 125 (17) ◽

pp. 3483-3496 ◽

Cited By ~ 7

Author(s):

F. Tie ◽

T. Furuyama ◽

P.J. Harte

Keyword(s):

Polycomb Group ◽

Homeotic Genes ◽

Polycomb Group Proteins ◽

Polycomb Group Protein ◽

Polycomb Group Genes ◽

Evolutionarily Conserved ◽

Group Protein ◽

Essential Prerequisite

The Polycomb Group gene esc encodes an evolutionarily conserved protein required for transcriptional silencing of the homeotic genes. Unlike other Polycomb Group genes, esc is expressed and apparently required only during early embryogenesis, suggesting it is required for the initial establishment of silencing but not for its subsequent maintenance. We present evidence that the ESC protein interacts directly with E(Z), another Polycomb Group protein required for silencing of the homeotic genes. We show that the most highly conserved region of ESC, containing seven WD motifs that are predicted to fold into a beta-propeller structure, mediate its binding to a conserved N-terminal region of E(Z). Mutations in the WD region that perturb ESC silencing function in vivo also perturb binding to E(Z) in vitro. The entire WD region forms a trypsin-resistant structure, like known beta -propeller domains, and mutations that would affect the predicted ESC beta-propeller perturb its trypsin-resistance, while a putative structure-conserving mutation does not. We show by co-immunoprecipitation that ESC and E(Z) are directly associated in vivo and that they also co-localize at many chromosomal binding sites. Since E(Z) is required for binding of other Polycomb Group proteins to chromosomes, these results suggest that formation of an E(Z):ESC complex at Polycomb Response Elements may be an essential prerequisite for the establishment of silencing.

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A Drosophila growth factor homolog, decapentaplegic, regulates homeotic gene expression within and across germ layers during midgut morphogenesis

Development ◽

10.1242/dev.110.4.1041 ◽

1990 ◽

Vol 110 (4) ◽

pp. 1041-1050 ◽

Cited By ~ 24

Author(s):

G.E. Panganiban ◽

R. Reuter ◽

M.P. Scott ◽

F.M. Hoffmann

Keyword(s):

Gene Expression ◽

Growth Factor ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Homeotic Gene ◽

Homeotic Genes ◽

Germ Layers ◽

Visceral Mesoderm ◽

Endodermal Cells ◽

Homeotic Gene Expression

The decapentaplegic (dpp) gene product, a member of the transforming growth factor-beta family, is required in Drosophila embryos for normal gastrulation and the establishment of dorsal-ventral polarity in the embryo. dpp is also expressed at specific positions in the visceral mesoderm along the developing midgut. We find that mutations that eliminate the visceral mesoderm expression of dpp lead to defects in midgut morphogenesis and alter the spatially localized expression of the homeotic genes Sex combs reduced (Scr), Ultrabithorax (Ubx), and Antennapedia (Antp) in the visceral mesoderm. The extracellular dpp protein migrates from the visceral mesoderm across the apposing endodermal cell layer in a region of the endoderm that expresses the homeotic gene labial (lab). Mesodermal expression of dpp is required for the expression of lab in these endodermal cells indicating that dpp mediates an inductive interaction between the two germ layers. We propose that extracellular dpp protein regulates gut morphogenesis, in part, by regulating homeotic gene expression in the visceral mesoderm and endoderm of the developing midgut.

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Dissecting the temporal requirements for homeotic gene function

Development ◽

10.1242/dev.120.7.1983 ◽

1994 ◽

Vol 120 (7) ◽

pp. 1983-1995 ◽

Cited By ~ 16

Author(s):

J. Castelli-Gair ◽

S. Greig ◽

G. Micklem ◽

M. Akam

Keyword(s):

Gene Expression ◽

Nervous System ◽

Gene Function ◽

Cell Types ◽

Homeotic Gene ◽

Homeotic Genes ◽

Bithorax Complex ◽

Cell Type ◽

Homeotic Gene Expression

Homeotic genes confer identity to the different segments of Drosophila. These genes are expressed in many cell types over long periods of time. To determine when the homeotic genes are required for specific developmental events we have expressed the Ultrabithorax, abdominal-A and Abdominal-Bm proteins at different times during development using the GAL4 targeting technique. We find that early transient homeotic gene expression has no lasting effects on the differentiation of the larval epidermis, but it switches the fate of other cell types irreversibly (e.g. the spiracle primordia). We describe one cell type in the peripheral nervous system that makes sequential, independent responses to homeotic gene expression. We also provide evidence that supports the hypothesis of in vivo competition between the bithorax complex proteins for the regulation of their down-stream targets.

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Engrailed-mediated repression of Ultrabithorax is necessary for the parasegment 6 identity in Drosophila

Development ◽

10.1242/dev.120.11.3205 ◽

1994 ◽

Vol 120 (11) ◽

pp. 3205-3212 ◽

Cited By ~ 5

Author(s):

R.S. Mann

Keyword(s):

Gene Expression ◽

Heat Shock ◽

Homeotic Gene ◽

Homeotic Genes ◽

Posterior Compartment ◽

Anterior Compartment ◽

Heat Shock Promoter ◽

Sensory Structures ◽

Different Levels ◽

Homeotic Gene Expression

The homeotic genes of Drosophila are expressed in overlapping domains along the anterior-to-posterior axis and specify the distinct morphological patterns of each parasegment. Within single parasegments, the levels of homeotic gene expression are often modulated, in part because of cross-regulation by other homeotic gene products. However, the functional significance of different levels of homeotic gene expression is unclear. Here modulations in Ultrabithorax (Ubx) expression within parasegment 6 are examined. Specifically, Ubx is shown to be down-regulated in the posterior compartment of this parasegment by engrailed (en). The significance of Ubx repression by en was demonstrated by characterizing the expression of the Ubx target gene, Distal-less (Dll). In the posterior compartment of parasegment 6, Dll is normally expressed in a small cluster of cells. If Ubx is expressed uniformly via a heat-shock promoter, Dll is inappropriately repressed in these posterior compartment cells. In the anterior compartment of parasegment 6, Dll is normally repressed by high levels of Ubx. However, if en is expressed uniformly via a heat-shock promoter, Ubx is repressed and Dll is derepressed. Because Dll is required for the development of larval sensory structures, these results demonstrate that en-mediated repression of Ubx in the posterior compartment is necessary for the morphology of parasegment 6. Thus, different levels of homeotic gene expression can be important for their segmental patterning functions.

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