Genetic analysis of the additional sex combs locus of Drosophila melanogaster.

Abstract Additional sex combs (Asx) is a member of the Polycomb group of genes, which are thought to be required for maintenance of chromatin structure. To better understand the function of Asx, we have isolated nine new alleles, each of which acts like a gain of function mutation. Asx is required for normal determination of segment identity. AsxP1 shows an unusual phenotype in that anterior and posterior homeotic transformations are seen in the same individuals, suggesting that AsxP1 might upset chromatin structure in a way that makes both activation and repression of homeotic genes more difficult. Analysis of embryonic and adult phenotypes of Asx alleles suggests that Asx is required zygotically for determination of segment number and polarity. The expression pattern of even-skipped is altered in Asx mutant embryos, suggesting that Asx is required for normal expression of this gene. We have transposon-tagged the Asx gene, and can thus begin molecular analysis of its function.

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

Genetics ◽

10.1093/genetics/149.4.1823 ◽

1998 ◽

Vol 149 (4) ◽

pp. 1823-1838 ◽

Cited By ~ 1

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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Comparison of germline mosaics of genes in the Polycomb group of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/140.1.231 ◽

1995 ◽

Vol 140 (1) ◽

pp. 231-243 ◽

Cited By ~ 5

Author(s):

M C Soto ◽

T B Chou ◽

W Bender

Keyword(s):

Drosophila Melanogaster ◽

Target Genes ◽

Cell Types ◽

Mitotic Recombination ◽

Polycomb Group ◽

Specific Cell ◽

Independent Functions ◽

Sex Combs ◽

Null Phenotype ◽

Additional Sex Combs

Abstract The genes of the Polycomb group (PcG) repress the genes of the bithorax and Antennapedia complexes, among others. To observe a null phenotype for a PcG gene, one must remove its maternal as well as zygotic contribution to the embryo. Five members of the PcG group are compared here: Enhancer of Polycomb [E(Pc)], Additional sex combs (Asx), Posterior sex combs (Psc), Suppressor of zeste 2 [Su (z) 2] and Polycomblike (Pcl). The yeast recombinase (FLP) system was used to induce mitotic recombination in the maternal germline. Mutant embryos were analyzed by staining with antibodies against six target genes of the PcG. The loss of the maternal component leads to enhanced homeotic phenotypes and to unique patterns of misexpression. E(Pc) and Su(z) 2 mutations had only subtle effects on the target genes, even when the maternal contributions were removed. Asx and Pcl mutants show derepression of the targets only in specific cell types. Psc shows unusual effects on two of the targets, Ultrabithorax and abdominal-A. These results show that the PcG genes do not act only in a common complex or pathway; they must have some independent functions.

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Mutations in the Drosophila melanogaster Gene Encoding S-adenosylmethionine Suppress Position-Effect Variegation

Genetics ◽

10.1093/genetics/143.2.887 ◽

1996 ◽

Vol 143 (2) ◽

pp. 887-896 ◽

Cited By ~ 3

Author(s):

Jan Larsson ◽

Jingpu Zhang ◽

Åsa Rasmuson-Lestander

Keyword(s):

Drosophila Melanogaster ◽

Chromatin Structure ◽

Position Effect ◽

Regulatory Region ◽

Polycomb Group ◽

Position Effect Variegation ◽

Gene Encoding ◽

Sex Combs ◽

S Alleles ◽

Effect Variegation

Abstract In Drosophila melanogaster, the study of trans-acting modifier mutations of position-effect variegation and Polycomb group (Pc-G) genes have been useful tools to investigate genes involved in chromatin structure. We have cloned a modifier gene, Suppesssm of zeste 5 (Su(z)5), which encodes Sadenosylmethionine synthetase, and we present here molecular results and data concerning its expression in mutants and genetic interactions. The mutant alleles Su(z)5, l(2)R23 and l(2)M6 show suppression of wm4 and also of two white mutants induced by roo element insertions in the regulatory region i.e., wis (in combination with z 1) and wsp1. Two of the Su(z)S alleles, as well as a deletion of the gene, also act as enhancers of PoZycomb by increasing the size of sex combs on midleg. The results suggest that Su(z)5 is connected with regulation of chromatin structure. The enzyme Sadenosylmethionine synthetase is involved in the synthesis of Sadenosylmethionine, a methyl group donor and also, after decarboxylation, a propylamino group donor in the bio-synthesis of polyamines. Our results from HPLC analysis show that in ovaries from heterozygous Su(z)5 mutants the content of spermine is significantly reduced. Results presented here suggest that polyamines are an important molecule class in the regulation of chromatin structure.

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DSP1, an HMG-like Protein, Is Involved in the Regulation of Homeotic Genes

Genetics ◽

10.1093/genetics/157.1.237 ◽

2001 ◽

Vol 157 (1) ◽

pp. 237-244

Author(s):

M Decoville ◽

E Giacomello ◽

M Leng ◽

D Locker

Keyword(s):

Null Allele ◽

Genetic Interaction ◽

Polycomb Group ◽

Homeotic Genes ◽

Loss Of Function ◽

Sex Combs Reduced ◽

Trithorax Group ◽

Sex Combs ◽

Normal Expression ◽

Sex Comb

Abstract The Drosophila dsp1 gene, which encodes an HMG-like protein, was originally identified in a screen for corepressors of Dorsal. Here we report that loss of dsp1 function causes homeotic transformations resembling those associated with loss of function in the homeotic genes Sex combs reduced (Scr), Ultrabithorax (Ubx), and Abdominal-B. The expression pattern of Scr is altered in dsp1 mutant imaginal discs, indicating that dsp1 is required for normal expression of this gene. Genetic interaction studies reveal that a null allele of dsp1 enhances trithorax-group gene (trx-G) mutations and partially suppresses Polycomb-group gene (Pc-G) mutations. On the contrary, overexpression of dsp1 induces an enhancement of the transformation of wings into halteres and of the extra sex comb phenotype of Pc. In addition, dsp1 male mutants exhibit a mild transformation of A4 into A5. Comparison of the chromatin structure at the Mcp locus in wild-type and dsp1 mutant embryos reveals that the 300-bp DNase I hypersensitive region is absent in a dsp1 mutant context. We propose that DSP1 protein is a chromatin remodeling factor, acting as a trx-G or a Pc-G protein depending on the considered function.

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The Additional sex combs gene of Drosophila encodes a chromatin protein that binds to shared and unique Polycomb group sites on polytene chromosomes

Development ◽

10.1242/dev.125.7.1207 ◽

1998 ◽

Vol 125 (7) ◽

pp. 1207-1216 ◽

Cited By ~ 9

Author(s):

D.A. Sinclair ◽

T.A. Milne ◽

J.W. Hodgson ◽

J. Shellard ◽

C.A. Salinas ◽

...

Keyword(s):

Target Genes ◽

Position Effect ◽

Polytene Chromosomes ◽

Polycomb Group ◽

Position Effect Variegation ◽

Sex Combs ◽

Effect Variegation ◽

The Central Nervous System ◽

Additional Sex Combs ◽

Site Recognition

The Additional sex combs (Asx) gene of Drosophila is a member of the Polycomb group of genes, which are required for maintenance of stable repression of homeotic and other loci. Asx is unusual among the Polycomb group because: (1) one Asx allele exhibits both anterior and posterior transformations; (2) Asx mutations enhance anterior transformations of trx mutations; (3) Asx mutations exhibit segmentation phenotypes in addition to homeotic phenotypes; (4) Asx is an Enhancer of position-effect variegation and (5) Asx displays tissue-specific derepression of target genes. Asx was cloned by transposon tagging and encodes a protein of 1668 amino acids containing an unusual cysteine cluster at the carboxy terminus. The protein is ubiquitously expressed during development. We show that Asx is required in the central nervous system to regulate Ultrabithorax. ASX binds to multiple sites on polytene chromosomes, 70% of which overlap those of Polycomb, polyhomeotic and Polycomblike, and 30% of which are unique. The differences in target site recognition may account for some of the differences in Asx phenotypes relative to other members of the Polycomb group.

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Role of the esc+ gene product in ensuring the selective expression of segment-specific homeotic genes in Drosophila

Development ◽

10.1242/dev.76.1.297 ◽

1983 ◽

Vol 76 (1) ◽

pp. 297-331

Author(s):

Gary Struhl

Keyword(s):

Gene Product ◽

The Body ◽

Homeotic Genes ◽

Bithorax Complex ◽

Sex Combs Reduced ◽

Sex Combs ◽

Correct Determination ◽

Correct Expression

The product of the extra sex combs+ (esc+) gene is required during embryogenesis for the correct determination of segments in Drosophila. If this product is absent, most segments develop like the normal eighth abdominal segment. Here, I extend previous results (Struhl, 1981a) showing that this phenotype results in large part from indiscriminate expression of the bithorax-complex genes which are normally active only in particular segments of the thorax and abdomen. In addition, I test whether the esc+ gene product is required for the correct expression of other homeotic genes. First, I have examined two genes of the Antennapedia-complex (Sex combs reduced+ and Antennapedia+): I find that both genes are normally required in only some of the body segments, but that in the absence of the esc+ gene product, both appear to function adventitiously in other segments. Second, comparing esc+ and esc− embryos lacking both these genes as well as the bithorax-complex, I find that additional homeotic genes (possibly those normally involved in specifying head segments) appear to be expressed indiscriminately when the esc+ gene product is absent. Finally, I present evidence that the products of the esc+ gene and the Polycomb+ gene (a second gene required for the correct regulation of the bithorax-complex) act independently. On the basis of these results, I propose a tentative outline of the roles and realms of action of all of these genes.

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

Development ◽

10.1242/dev.120.9.2629 ◽

1994 ◽

Vol 120 (9) ◽

pp. 2629-2636 ◽

Cited By ~ 19

Author(s):

A. Lonie ◽

R. D'Andrea ◽

R. Paro ◽

R. Saint

Keyword(s):

Gene Expression ◽

Drosophila Melanogaster ◽

Polycomb Group ◽

Negative Regulator ◽

Homeotic Gene ◽

Homeotic Genes ◽

Molecular Characterisation ◽

Polycomb Group Proteins ◽

Polycomb Group Genes ◽

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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H3K27 modifications define segmental regulatory domains in the Drosophila bithorax complex

eLife ◽

10.7554/elife.02833 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 69

Author(s):

Sarah K Bowman ◽

Aimee M Deaton ◽

Heber Domingues ◽

Peggy I Wang ◽

Ruslan I Sadreyev ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Binding Protein ◽

Histone H3 ◽

Polycomb Group ◽

Homeotic Genes ◽

Bithorax Complex ◽

Body Segment ◽

Regulatory Domains ◽

Definition Of ◽

Identity Expression

The bithorax complex (BX-C) in Drosophila melanogaster is a cluster of homeotic genes that determine body segment identity. Expression of these genes is governed by cis-regulatory domains, one for each parasegment. Stable repression of these domains depends on Polycomb Group (PcG) functions, which include trimethylation of lysine 27 of histone H3 (H3K27me3). To search for parasegment-specific signatures that reflect PcG function, chromatin from single parasegments was isolated and profiled. The H3K27me3 profiles across the BX-C in successive parasegments showed a ‘stairstep’ pattern that revealed sharp boundaries of the BX-C regulatory domains. Acetylated H3K27 was broadly enriched across active domains, in a pattern complementary to H3K27me3. The CCCTC-binding protein (CTCF) bound the borders between H3K27 modification domains; it was retained even in parasegments where adjacent domains lack H3K27me3. These findings provide a molecular definition of the homeotic domains, and implicate precisely positioned H3K27 modifications as a central determinant of segment identity.

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Ten different Polycomb group genes are required for spatial control of the abdA and AbdB homeotic products

Development ◽

10.1242/dev.114.2.493 ◽

1992 ◽

Vol 114 (2) ◽

pp. 493-505 ◽

Cited By ~ 28

Author(s):

J. Simon ◽

A. Chiang ◽

W. Bender

Keyword(s):

Expression Patterns ◽

Ectopic Expression ◽

Specific Pattern ◽

Polycomb Group ◽

Polycomb Group Genes ◽

Sex Combs ◽

Normal Expression ◽

Sex Comb ◽

Regulatory Dna ◽

Pair Rule

Mutations in genes of the Polycomb (Pc) group cause abnormal segmental development due to ectopic expression of the homeotic products of the Antennapedia and bithorax complexes. Here the requirements for Pc group genes in controlling the abdA and AbdB products of the bithorax complex are described. Embryos containing mutations in the genes Polycomb (Pc), extra sex combs (esc), Enhancer of zeste [E(z)], polyhomeotic (ph), Sex comb on midleg (Scm), Polycomb-like (Pcl), Sex comb extra (Sce), Additional sex combs (Asx), Posterior sex combs (Psc) and pleiohomeotic (pho) were examined. In every case, both abdA and AbdB are expressed outside of their normal domains along the anterior-posterior (A-P) axis, consistent with these Pc group products acting in a single pathway or molecular complex. The earliest detectable ectopic expression is highest in the parasegments immediately adjacent to the normal expression boundary. Surprisingly, in the most severe Pc group mutants, the earliest ectopic AbdB is distributed in a pair-rule pattern. At all stages, ectopic abdA in the epidermis is highest along the anterior edges of the parasegments, in a pattern that mimics the normal abdA cell-specific pattern. These examples of highly patterned mis-expression show that Pc group mutations do not cause indiscriminate activation of homeotic products. We suggest that the ectopic expression patterns result from factors that normally activate abdA and AbdB only in certain parasegments, but that in Pc group mutants these factors gain access to regulatory DNA in all parasegments.

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