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

Development ◽  
1998 ◽  
Vol 125 (7) ◽  
pp. 1207-1216 ◽  
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.

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

Genetics ◽  
1996 ◽  
Vol 143 (2) ◽  
pp. 887-896 ◽  
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.

The enhancer of polycomb gene of Drosophila encodes a chromatin protein conserved in yeast and mammals

Development ◽  
1998 ◽  
Vol 125 (20) ◽  
pp. 4055-4066 ◽  
Author(s):  
K. Stankunas ◽  
J. Berger ◽  
C. Ruse ◽  
D.A. Sinclair ◽  
F. Randazzo ◽  
...  
Keyword(s):  
Position Effect ◽  
Polytene Chromosomes ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Chromatin Protein ◽  
Heterochromatin Formation ◽  
C Elegans ◽  
Polycomb Group Genes ◽  
Effect Variegation ◽  
Or Gene

The Polycomb group of genes in Drosophila are homeotic switch gene regulators that maintain homeotic gene repression through a possible chromatin regulatory mechanism. The Enhancer of Polycomb (E(Pc)) gene of Drosophila is an unusual member of the Polycomb group. Most PcG genes have homeotic phenotypes and are required for repression of homeotic loci, but mutations in E(Pc) exhibit no homeotic transformations and have only a very weak effect on expression of Abd-B. However, mutations in E(Pc) are strong enhancers of mutations in many Polycomb group genes and are also strong suppressors of position-effect variegation, suggesting that E(Pc) may have a wider role in chromatin formation or gene regulation than other Polycomb group genes. E(Pc) was cloned by transposon tagging, and encodes a novel 2023 amino acid protein with regions enriched in glutamine, alanine and asparagine. E(Pc) is expressed ubiquitously in Drosophila embryogenesis. E(Pc) is a chromatin protein, binding to polytene chromosomes at about 100 sites, including the Antennapedia but not the Bithorax complex, 29% of which are shared with Polycomb-binding sites. Surprisingly, E(Pc) was not detected in the heterochromatic chromocenter. This result suggests that E(Pc) has a functional rather than structural role in heterochromatin formation and argues against the heterochromatin model for PcG function. Using homology cloning techniques, we identified a mouse homologue of E(Pc), termed Epc1, a yeast protein that we name EPL1, and as well as additional ESTs from Caenorhabditis elegans, mice and humans. Epc1 shares a long, highly conserved domain in its amino terminus with E(Pc) that is also conserved in yeast, C. elegans and humans. The occurrence of E(Pc) across such divergent species is unusual for both PcG proteins and for suppressors of position-effect variegation, and suggests that E(Pc) has an important role in the regulation of chromatin structure in eukaryotes.

white+ Transgene Insertions Presenting a Dorsal/Ventral Pattern Define a Single Cluster of Homeobox Genes That Is Silenced by the Polycomb-group Proteins in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 257-275 ◽  
Author(s):  
Sophie Netter ◽  
Marie-Odile Fauvarque ◽  
Ruth Diez del Corral ◽  
Jean-Maurice Dura ◽  
Dario Coen
Keyword(s):  
Chromatin Structure ◽  
Target Genes ◽  
Position Effect ◽  
Phenotypic Expression ◽  
Positional Information ◽  
Genomic Region ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Trithorax Group ◽  
Clear Cut

AbstractWe used the white gene as an enhancer trap and reporter of chromatin structure. We collected white+ transgene insertions presenting a peculiar pigmentation pattern in the eye: white expression is restricted to the dorsal half of the eye, with a clear-cut dorsal/ventral (D/V) border. This D/V pattern is stable and heritable, indicating that phenotypic expression of the white reporter reflects positional information in the developing eye. Localization of these transgenes led us to identify a unique genomic region encompassing 140 kb in 69D1–3 subject to this D/V effect. This region contains at least three closely related homeobox-containing genes that are constituents of the iroquois complex (IRO-C). IRO-C genes are coordinately regulated and implicated in similar developmental processes. Expression of these genes in the eye is regulated by the products of the Polycomb -group (Pc-G) and trithorax-group (trx-G) genes but is not modified by classical modifiers of position-effect variegation. Our results, together with the report of a Pc -G binding site in 69D, suggest that we have identified a novel cluster of target genes for the Pc-G and trx-G products. We thus propose that ventral silencing of the whole IRO-C in the eye occurs at the level of chromatin structure in a manner similar to that of the homeotic gene complexes, perhaps by local compaction of the region into a heterochromatin-like structure involving the Pc-G products.

Enhancer of Polycomb Is a Suppressor of Position-Effect Variegation in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 148 (1) ◽  
pp. 211-220
Author(s):  
Donald A R Sinclair ◽  
Nigel J Clegg ◽  
Jennifer Antonchuk ◽  
Thomas A Milne ◽  
Kryn Stankunas ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Position Effect ◽  
Polycomb Group ◽  
P Element ◽  
Homeotic Gene ◽  
Position Effect Variegation ◽  
Negative Regulators ◽  
Recombination Mapping ◽  
Effect Variegation ◽  
Homeotic Gene Expression

Abstract Polycomb group (PcG) genes of Drosophila are negative regulators of homeotic gene expression required for maintenance of determination. Sequence similarity between Polycomb and Su(var)205 led to the suggestion that PcG genes and modifiers of position-effect variegation (PEV) might function analogously in the establishment of chromatin structure. If PcG proteins participate directly in the same process that leads to PEV, PcG mutations should suppress PEV. We show that mutations in E(Pc), an unusual member of the PcG, suppress PEV of four variegating rearrangements: In(l)wm4, BSV, T(2;3)SbV, and In(2R)bwVDe2. Using reversion of a P element insertion, deficiency mapping, and recombination mapping as criteria, homeotic effects and suppression of PEV associated with E(Pc) co-map. Asx is an enhancer of PEV, whereas nine other PcG loci do not affect PEV. These results support the conclusion that there are fewer similarities between PcG genes and modifiers of PEV than previously supposed. However, E(Pc) appears to be an important link between the two groups. We discuss why Asx might act as an enhancer of PEV.

scholarly journals Replication of Heterochromatin and Structure of Polytene Chromosomes

2000 ◽  
Vol 20 (17) ◽  
pp. 6308-6316 ◽  
Author(s):  
Thomas J. Leach ◽  
Heather L. Chotkowski ◽  
Michael G. Wotring ◽  
Robert L. Dilwith ◽  
Robert L. Glaser
Keyword(s):  
Temporal Pattern ◽  
Position Effect ◽  
Polytene Chromosomes ◽  
S Phase ◽  
Parental Origin ◽  
Position Effect Variegation ◽  
Replication Forks ◽  
Satellite Sequences ◽  
Effect Variegation ◽  
Diploid Cells

ABSTRACT Heterochromatin is characteristically the last portion of the genome to be replicated. In polytene cells, heterochromatic sequences are underreplicated because S phase ends before replication of heterochromatin is completed. Truncated heterochromatic DNAs have been identified in polytene cells of Drosophila and may be the discontinuous molecules that form between fully replicated euchromatic and underreplicated heterochromatic regions of the chromosome. In this report, we characterize the temporal pattern of heterochromatic DNA truncation during development of polytene cells. Underreplication occurred during the first polytene S phase, yet DNA truncation, which was found within heterochromatic sequences of all fourDrosophila chromosomes, did not occur until the second polytene S phase. DNA truncation was correlated with underreplication, since increasing the replication of satellite sequences with thecycE 1672 mutation caused decreased production of truncated DNAs. Finally, truncation of heterochromatic DNAs was neither quantitatively nor qualitatively affected by modifiers of position effect variegation including the Y chromosome,Su(var)2052 , parental origin, or temperature. We propose that heterochromatic satellite sequences present a barrier to DNA replication and that replication forks that transiently stall at such barriers in late S phase of diploid cells are left unresolved in the shortened S phase of polytene cells. DNA truncation then occurs in the second polytene S phase, when new replication forks extend to the position of forks left unresolved in the first polytene S phase.

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

Genetics ◽  
1995 ◽  
Vol 140 (1) ◽  
pp. 231-243 ◽  
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.

Dynamics of the sub-nuclear distribution of Modulo and the regulation of position-effect variegation by nucleolus in Drosophila

1998 ◽  
Vol 111 (18) ◽  
pp. 2753-2761 ◽  
Author(s):  
L. Perrin ◽  
O. Demakova ◽  
L. Fanti ◽  
S. Kallenbach ◽  
S. Saingery ◽  
...  
Keyword(s):  
Ribosome Biogenesis ◽  
Position Effect ◽  
Polytene Chromosomes ◽  
Molecular Networks ◽  
Relaxation Processes ◽  
Position Effect Variegation ◽  
Cell Fractionation ◽  
Chromatin Compaction ◽  
Nuclear Distribution ◽  
Effect Variegation

modulo belongs to the class of Drosophila genes named ‘suppressor of position-effect variegation’, suggesting the involvement of the encoded protein in chromatin compaction/relaxation processes. Using complementary procedures of cell fractionation, immunolocalisation on mitotic and polytene chromosomes and cross-linking/immunoprecipitation of genomic DNA targets, we have analysed the sub-nuclear distribution of Modulo. While actually associated to condensed chromatin and heterochromatin sites, the protein is also abundantly found at nucleolus. From a comparison of Modulo pattern on chromosomes of different cell types and mutant lines, we propose a model in which the nucleolus balances the Modulo protein available for chromatin compaction and PEV modification. At a molecular level, repetitive elements instead of rDNA constitute Modulo DNA targets, indicating that the protein directly contacts DNA in heterochromatin but not at the nucleolus. Consistent with a role for Modulo in nucleolus activity and protein synthesis capacity, somatic clones homozygous for a null mutation express a cell-autonomous phenotype consisting of growth alteration and short slender bristles, characteristic traits of Minute mutations, which are known to affect ribosome biogenesis. The results provide evidence suggesting that Modulo participates in distinct molecular networks in the nucleolus and heterochromatin and has distinct functions in the two compartments.

scholarly journals In Vivo Chromatin Accessibility Correlates With Gene Silencing in Drosophila

Genetics ◽  
1998 ◽  
Vol 150 (4) ◽  
pp. 1539-1549 ◽  
Author(s):  
Antoine Boivin ◽  
Jean-Maurice Dura
Keyword(s):  
Gene Silencing ◽  
Chromatin Structure ◽  
Dna Methyltransferase ◽  
Target Genes ◽  
Position Effect ◽  
Chromatin Accessibility ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Direct Support

Abstract Gene silencing by heterochromatin is a well-known phenomenon that, in Drosophila, is called position effect variegation (PEV). The long-held hypothesis that this gene silencing is associated with an altered chromatin structure received direct support only recently. Another gene-silencing phenomenon in Drosophila, although similar in its phenotype of variegation, has been shown to be associated with euchromatic sequences and is dependent on developmental regulators of the Polycomb group (Pc-G) of gene products. One model proposes that the Pc-G products may cause a local heterochromatinization that maintains a repressed state of transcription of their target genes. Here, we test these models by measuring the accessibility of white or miniwhite sequences, in different contexts, to the Escherichia coli dam DNA methyltransferase in vivo. We present evidence that PEV and Pc-G-mediated repression mechanisms, although based on different protein factors, may indeed involve similar higher-order chromatin structure.

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

Development ◽  
2001 ◽  
Vol 128 (17) ◽  
pp. 3371-3379 ◽  
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.

scholarly journals Genetic and Molecular Complexity of the Position Effect Variegation Modifier mod(mdg4) in Drosophila

Genetics ◽  
2000 ◽  
Vol 155 (1) ◽  
pp. 141-157 ◽  
Author(s):  
Kerstin Büchner ◽  
Peggy Roth ◽  
Gunnar Schotta ◽  
Veiko Krauss ◽  
Harald Saumweber ◽  
...  
Keyword(s):  
Amino Acids ◽  
Splice Variants ◽  
Consensus Sequence ◽  
Position Effect ◽  
Polytene Chromosomes ◽  
Genomic Region ◽  
Protein Isoforms ◽  
Large Set ◽  
Position Effect Variegation ◽  
Effect Variegation

Abstract mod(mdg4), also known as E(var)3-93D, is involved in a variety of processes, such as gene silencing in position effect variegation (PEV), the control of gypsy insulator sequences, regulation of homeotic gene expression, and programmed cell death. We have isolated a large number of mod(mdg4) cDNAs, representing 21 different isoforms generated by alternative splicing. The deduced proteins are characterized by a common N terminus of 402 amino acids, including the BTB/POZ-domain. Most of the variable C termini contain a new consensus sequence, including four positioned hydrophobic amino acids and a Cys2His2 motif. Using specific antibodies for two protein isoforms, we demonstrate different distributions of the corresponding proteins on polytene chromosomes. Mutations in the genomic region encoding exons 1–4 show enhancement of PEV and homeotic transformation and affect viability and fertility. Homeotic and PEV phenotypes are enhanced by mutations in other trx-group genes. A transgene containing the common 5′ region of mod(mdg4) that is present in all splice variants known so far partially rescues the recessive lethality of mod(mdg4) mutant alleles. Our data provide evidence that the molecular and genetic complexity of mod(mdg4) is caused by a large set of individual protein isoforms with specific functions in regulating the chromatin structure of different sets of genes throughout development.

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