scholarly journals Trans-Silencing by P Elements Inserted in Subtelomeric Heterochromatin Involves the Drosophila Polycomb Group Gene, Enhancer of zeste

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1839-1855 ◽  
Author(s):  
Siobhan E Roche ◽  
Donald C Rio
Keyword(s):  
Transcriptional Repression ◽  
Protein Product ◽  
Polycomb Group ◽  
P Element ◽  
Subtelomeric Heterochromatin ◽  
P Elements ◽  
Enhancer Of Zeste ◽  
Gene Enhancer ◽  
Associated Sequences ◽  
Polycomb Group Gene

AbstractDrosophila P-element transposition is regulated by a maternally inherited state known as P cytotype. An important aspect of P cytotype is transcriptional repression of the P-element promoter. P cytotype can also repress non-P-element promoters within P-element ends, suggesting that P cytotype repression might involve chromatin-based transcriptional silencing. To learn more about the role of chromatin in P cytotype repression, we have been studying the P strain Lk-P(1A). This strain contains two full-length P elements inserted in the heterochromatic telomere-associated sequences (TAS elements) at cytological location 1A. Mutations in the Polycomb group gene (Pc-G gene), Enhancer of zeste (E(z)), whose protein product binds at 1A, resulted in a loss of Lk-P(1A) cytotype control. E(z) mutations also affected the trans-silencing of heterologous promoters between P-element termini by P-element transgenes inserted in the TAS repeats. These data suggest that pairing interactions between P elements, resulting in exchange of chromatin structures, may be a mechanism for controlling the expression and activity of P elements.

The Drosophila Polycomb-group gene Enhancer of zeste contains a region with sequence similarity to trithorax

1993 ◽  
Vol 13 (10) ◽  
pp. 6357-6366
Author(s):  
R S Jones ◽  
W M Gelbart
Keyword(s):  
Amino Acids ◽  
Sequence Similarity ◽  
Protein Product ◽  
Polycomb Group ◽  
Acute Leukemias ◽  
Trithorax Group ◽  
Acid Protein ◽  
Enhancer Of Zeste ◽  
Gene Enhancer ◽  
Carboxy Terminal

As is typical of Polycomb-group loci, the Enhancer of zeste [E(z)] gene negatively regulates the segment identity genes of the Antennapedia (ANT-C) and Bithorax (BX-C) gene complexes. A second class of loci, collectively known as the trithorax group, plays an antagonistic role as positive regulators of the ANT-C and BX-C genes. Molecular analysis of the E(z) gene predicts a 760-amino-acid protein product. A region of 116 amino acids near the E(z) carboxy terminus is 41.2% identical (68.4% similar) with a carboxy-terminal region of the trithorax protein. This portion of the trithorax protein is part of a larger region previously shown to share extensive homology with a human protein (ALL-1/Hrx) that is implicated in acute leukemias. Over this same 116 amino acids, E(z) and ALL-1/Hrx are 43.9% identical (68.4% similar). Otherwise, E(z) is not significantly similar to any previously described proteins. As this region of sequence similarity is shared by two proteins with antagonistic functions, we suggest that it may comprise a domain that interacts with a common target, either nucleic acid or protein. Opposite effects on transcription might then be determined by other portions of the two proteins.

scholarly journals The Drosophila Polycomb-group gene Enhancer of zeste contains a region with sequence similarity to trithorax.

1993 ◽  
Vol 13 (10) ◽  
pp. 6357-6366 ◽  
Author(s):  
R S Jones ◽  
W M Gelbart
Keyword(s):  
Amino Acids ◽  
Sequence Similarity ◽  
Protein Product ◽  
Polycomb Group ◽  
Acute Leukemias ◽  
Trithorax Group ◽  
Acid Protein ◽  
Enhancer Of Zeste ◽  
Gene Enhancer ◽  
Carboxy Terminal

As is typical of Polycomb-group loci, the Enhancer of zeste [E(z)] gene negatively regulates the segment identity genes of the Antennapedia (ANT-C) and Bithorax (BX-C) gene complexes. A second class of loci, collectively known as the trithorax group, plays an antagonistic role as positive regulators of the ANT-C and BX-C genes. Molecular analysis of the E(z) gene predicts a 760-amino-acid protein product. A region of 116 amino acids near the E(z) carboxy terminus is 41.2% identical (68.4% similar) with a carboxy-terminal region of the trithorax protein. This portion of the trithorax protein is part of a larger region previously shown to share extensive homology with a human protein (ALL-1/Hrx) that is implicated in acute leukemias. Over this same 116 amino acids, E(z) and ALL-1/Hrx are 43.9% identical (68.4% similar). Otherwise, E(z) is not significantly similar to any previously described proteins. As this region of sequence similarity is shared by two proteins with antagonistic functions, we suggest that it may comprise a domain that interacts with a common target, either nucleic acid or protein. Opposite effects on transcription might then be determined by other portions of the two proteins.

scholarly journals The Regulatory Properties of Autonomous Subtelomeric P Elements Are Sensitive to a Suppressor of variegation in Drosophila melanogaster

Genetics ◽  
1996 ◽  
Vol 143 (4) ◽  
pp. 1663-1674 ◽  
Author(s):  
Stéphane Ronsseray ◽  
Monique Lehmann ◽  
Danielle Nouaud ◽  
Dominique Anxolabéhère
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Recombination ◽  
Natural Populations ◽  
P Element ◽  
Single Element ◽  
Heterochromatin Protein 1 ◽  
X Chromosomes ◽  
P Elements ◽  
Associated Sequences ◽  
Regulatory Properties

Abstract Genetic recombination was used in Drosophila melanogaster to isolate P elements, inserted at the telomeres of X chromosomes (cytological site 1A) from natural populations, in a genetic background devoid of other P elements. We show that complete maternally inherited P repression in the germline (P cytotype) can be elicited by only two autonomous P elements at 1A and that a single element at this site has partial regulatory properties. The analysis of the surrounding chromosomal regions of the P elements at 1A shows that in all cases these elements are flanked by Telomeric Associated Sequences, tandemly repetitive noncoding sequences that have properties of heterochromatin. In addition, we show that the regulatory properties of P elements at 1A can be inhibited by some of the mutant alleles of the Su(var)205 gene and by a deficiency of this gene. However, the regulatory properties of reference P strains (Harwich and Texas 007) are not impaired by Su(var)205 mutations. Su(var)205 encodes Heterochromatin Protein 1 (HP1). These results suggest that the HP1 dosage effect on the P element properties is sitedependent and could involve the structure of the chromatin.

E(z): a polycomb group gene or a trithorax group gene?

Development ◽  
1996 ◽  
Vol 122 (7) ◽  
pp. 2189-2197 ◽  
Author(s):  
D. LaJeunesse ◽  
A. Shearn
Keyword(s):  
Polycomb Group ◽  
Bithorax Complex ◽  
Trithorax Group ◽  
Polycomb Group Genes ◽  
Enhancer Of Zeste ◽  
Selector Genes ◽  
Homeotic Selector Genes ◽  
Polycomb Group Gene ◽  
Anterior Posterior ◽  
Homeotic Selector

The products of the Polycomb group of genes are cooperatively involved in repressing expression of homeotic selector genes outside of their appropriate anterior/posterior boundaries. Loss of maternal and/or zygotic function of Polycomb group genes results in the ectopic expression of both Antennapedia Complex and Bithorax Complex genes. The products of the trithorax group of genes are cooperatively involved in maintaining active expression of homeotic selector genes within their appropriate anterior/posterior boundaries. Loss of maternal and/or zygotic function of trithorax group genes results in reduced expression of both Antennapedia Complex and Bithorax Complex genes. Although Enhancer of zeste has been classified as a member of the Polycomb group, in this paper we show that Enhancer of zeste can also be classified as a member of the trithorax group. The requirement for Enhancer of zeste activity as either a trithorax group or Polycomb group gene depends on the homeotic selector gene locus as well as on spatial and temporal cues.

scholarly journals Analysis of subtelomeric heterochromatin in the Drosophila minichromosome Dp1187 by single P element insertional mutagenesis.

Genetics ◽  
1992 ◽  
Vol 132 (3) ◽  
pp. 737-753 ◽  
Author(s):  
G H Karpen ◽  
A C Spradling
Keyword(s):  
Insertional Mutagenesis ◽  
Position Effect ◽  
P Element ◽  
Centromeric Heterochromatin ◽  
Small Subset ◽  
Position Effect Variegation ◽  
Subtelomeric Heterochromatin ◽  
P Elements ◽  
Salivary Gland Cells ◽  
And Function

Abstract We investigated whether single P element insertional mutagenesis could be used to analyze heterochromatin within the Drosophila minichromosome Dp1187. Forty-five insertions of the P[lacZ,rosy+] element onto Dp1187 (recovered among 7,825 transpositions) were highly clustered. None was recovered in centromeric heterochromatin, but 39 occurred about 40 kb from the distal telomere within a 4.7-kb hotspot containing tandem copies of a novel 1.8-kb repetitive DNA sequence. The DNA within and distal to this region lacked essential genes and displayed several other properties characteristic of heterochromatin. The rosy+ genes within the inserted transposons were inhibited by position-effect variegation, and the subtelomeric region was underrepresented in polytene salivary gland cells. These experiments demonstrated that P elements preferentially transpose into a small subset of heterochromatic sites, providing a versatile method for studying the structure and function of these chromosome regions. This approach revealed that a Drosophila chromosome contains a large region of subtelomeric heterochromatin with specific structural and genetic properties.

A role for mel-18, a Polycomb group-related vertebrate gene, during theanteroposterior specification of the axial skeleton

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1513-1522 ◽  
Author(s):  
T. Akasaka ◽  
M. Kanno ◽  
R. Balling ◽  
M.A. Mieza ◽  
M. Taniguchi ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Transcriptional Repression ◽  
Ectopic Expression ◽  
Axial Skeleton ◽  
Polycomb Group ◽  
Paraxial Mesoderm ◽  
Gene Products ◽  
Polycomb Group Genes ◽  
Sex Combs ◽  
Polycomb Group Gene

Segment identity in both invertebrates and vertebrates is conferred by spatially restricted distribution of homeotic gene products. In Drosophila, the expression of Homeobox genes during embryogenesis is initially induced by segmentation gene products and then maintained by Polycomb group and Trithorax group gene products. Polycomb group gene homologs are conserved in vertebrates. Murine mel-18 and closely related bmi-1 are homologous to posterior sex combs and suppressor two of zeste. Mel-18 protein mediates a transcriptional repression via direct binding to specific DNA sequences. To gain further insight into the function of Mel-18, we have inactivated the mel-18 locus by homologous recombination. Mice lacking mel-18 survive to birth and die around 4 weeks after birth after exhibiting strong growth retardation. Similar to the Drosophila posterior sex combs mutant, posterior transformations of the axial skeleton were reproducibly observed in mel-18 mutants. The homeotic transformations were correlated with ectopic expression of Homeobox cluster genes along the anteroposterior axis in the developing paraxial mesoderm. Surprisingly, mel-18-deficient phenotypes are reminiscent of bmi-1 mutants. These results indicate that the vertebrate Polycomb group genes mel-18 and bmi-1, like Drosophila Polycomb group gene products, might play a crucial role in maintaining the silent state of Homeobox gene expression during paraxial mesoderm development.

Enhancer traps in the Drosophila bithorax complex mark parasegmental domains.

Genetics ◽  
1994 ◽  
Vol 138 (2) ◽  
pp. 387-399
Author(s):  
K McCall ◽  
M B O'Connor ◽  
W Bender
Keyword(s):  
Protein Pattern ◽  
Polycomb Group ◽  
P Element ◽  
Homeotic Genes ◽  
Bithorax Complex ◽  
Lacz Expression ◽  
Regulatory Regions ◽  
P Elements ◽  
Endogenous Genes ◽  
Beta Galactosidase

Abstract Eight P elements carrying a beta-galactosidase (lacZ) reporter have been mapped to sites within the Drosophila bithorax complex. The bithorax complex contains three homeotic genes, and at least nine regulatory regions which control their expression in successive parasegments of the fly. The enhancer traps inserted at the promoter of one of the genes, Ultrabithorax, express lacZ in patterns which mimic the Ultrabithorax protein pattern. Enhancer traps in the regulatory regions do not mimic the endogenous genes, but express lacZ globally in the relevant parasegments. Some P elements carry large DNA fragments upstream of the lacZ promoter but internal to the P element. In cases where these internal sequences specify a lacZ pattern, that pattern is generally suppressed when the element is inserted in the bithorax complex. In embryos mutant for genes of the Polycomb group, the lacZ expression from the enhancer traps spreads to all segments. Thus, the enhancer traps reveal parasegmental domains that are maintained by Polycomb-mediated repression. Such domains may be realized by parasegmental differences in chromatin structure.

scholarly journals P-Element Repression in Drosophila melanogaster by a Naturally Occurring Defective Telomeric P Copy

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 1841-1854 ◽  
Author(s):  
Laurent Marin ◽  
Monique Lehmann ◽  
Danielle Nouaud ◽  
Hassan Izaabel ◽  
Dominique Anxolabéhère ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Hybrid Dysgenesis ◽  
P Element ◽  
Tunisian Population ◽  
P Elements ◽  
Naturally Occurring ◽  
Dependent Component ◽  
Associated Sequences ◽  
Element Sequence

Abstract In Drosophila melanogaster, hybrid dysgenesis occurs in progeny from crosses between females lacking P elements and males carrying P elements scattered throughout the genome. We have genetically isolated a naturally occurring P insertion at cytological location 1A, from a Tunisian population. The Nasr'Allah-P(1A) element [NA-P(1A)] has a deletion of the first 871 bp including the P promoter. It is flanked at the 3′ end by telomeric associated sequences and at the 5′ end by a HeT-A element sequence. The NA-P(1A) element strongly represses dysgenic sterility and P transposition. However, when testing P-promoter repression, NA-P(1A) was unable to repress a germinally expressed P-lacZ construct bearing no 5′-homology with it. Conversely, a second P-lacZ construct, in which the fusion with lacZ takes place in exon 3 of P, was successfully repressed by NA-P(1A). This suggests that NA-P(1A) repression involves a homology-dependent component.

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