Mutants affecting position-effect heterochromatinization in Drosophila melanogaster

Reuter, Günter; Werner, W.; Hoffmann, H. J.

doi:10.1007/bf00327349

Cited by 72 publications

(33 citation statements)

References 14 publications

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“…Many workers have observed a striking correlation between the proportion of cells in which the variegating gene is packaged into heterochromatin and the degree to which a gene is expressed (19,42). At the genetic level specific mutations which modify position effect variegation in D. melanogaster have been described previously (43). The localization of the ClA9 antigen-encoding gene to 29A on the 2L chromosome is very intriguing.…”

Section: Resultsmentioning

confidence: 99%

Identification of a nonhistone chromosomal protein associated with heterochromatin in Drosophila melanogaster and its gene.

James¹,

Elgin²

1986

Mol. Cell. Biol.

574

388

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Monoclonal antibodies were prepared against a fraction of nuclear proteins of Drosophila melanogaster identified as tightly binding to DNA. Four of these antibodies were directed against a 19-kilodalton nuclear protein; immunofluorescence staining of the polytene chromosomes localized the antigen to the a, I, and intercalary heterochromatic regions. Screening of a Agtll cDNA expression library with one of the monoclonal antibodies identified a recombinant DNA phage clone that produced a fusion protein immunologically similar to the heterochromatin-associated protein. Polyclonal sera directed against the bacterial lacZ fusion protein recognized the same nuclear protein on Western blots. A full-length cDNA clone was isolated from a AgtlO library, and its DNA sequence was obtained. Analysis of the open reading frame revealed an 18,101-dalton protein encoded by this cDNA. Two overlapping genomic DNA clones were isolated from a Charon 4 library of D. melanogaster with the cDNA clone, and a restriction map was obtained. In situ hybridization with these probes indicated that the gene maps to a single chromosome location at 29A on the 2L chromosome. This general strategy should be effective for cloning the genes and identifying the genetic loci of chromosomal proteins which cannot be readily assayed by other means.In eucaryotic organisms, the genetic material exists as a complex between DNA, histones, and nonhistone chromosomal (NHC) proteins. The histones, whose primary structure has been highly conserved over evolution, are the protein components of the nucleosomes and as such are associated with almost all the DNA sequences of the genome. NHC proteins, therefore, are the leading candidates to play specific roles in the organization of higherorder chromatin structure and in the control of gene expression. It appears very likely that specific NHC proteins are involved in the compaction of nucleosomes into domains, the formation of specialized structures such as centromeres and telomeres, and the condensation of the chromatin fiber into the mitotic chromosome structure (9, 12). The presence or absence of various NHC proteins may also be critical in establishing the differences in structure between euchromatin and heterochromatin in the interphase nucleus.While a great deal of success has been obtained in the characterization of those NHC proteins with a known enzymatic function (16, 24), a systematic biochemical approach to the study of other NHC proteins has proven to be a difficult task. This may be attributed in part to their unusual physico-chemical properties (25), relatively low abundance, and lack of any functional assays. We chose an approach that allowed us to identify NHC proteins of Drosophila melanogaster by what is essentially a structural assay. Monoclonal antibodies prepared against fractionated nuclear proteins of D. melanogaster embryos are used in immunofluorescence staining of the polytene chromosomes of thirdinstar larvae of D. melanogaster. Those monoclonal antibodies that indicate a protein distrib...

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Section: Resultsmentioning

confidence: 99%

Identification of a nonhistone chromosomal protein associated with heterochromatin in Drosophila melanogaster and its gene.

James¹,

Elgin²

1986

Mol. Cell. Biol.

574

388

View full text Add to dashboard Cite

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“…1B). Moreover, these mutations appear to be general 3 To whom correspondence should be addressed. E-mail: kamiahmad@hms.harvard.edu.…”

Section: Xnp Remodeler Is a General De-repressor Of Heterochromatin Genementioning

confidence: 99%

“…Heterochromatic gene silencing has served as a sensitive measure to identify mutations in components of chromatin-based regulation (3,4). Transcriptional repression in heterochromatin is thought to be crucial to limit the accumulation of transposable elements and unstable repetitive sequences in genomes.…”

mentioning

confidence: 99%

The XNP remodeler targets dynamic chromatin in Drosophila

Schneiderman

Sakai

Goldstein

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Heterochromatic gene silencing results from the establishment of a repressive chromatin structure over reporter genes. Gene silencing is often variegated, implying that chromatin may stochastically switch from repressive to permissive structures as cells divide. To identify remodeling enzymes involved in reorganizing heterochromatin, we tested 11 SNF2-type chromatin remodelers in Drosophila for effects on gene silencing. Overexpression of five remodelers affects gene silencing, and the most potent de-repressor is the ␣-thalassaemia mental retardation syndrome X-linked (ATRX) homolog X-linked nuclear protein (XNP). Although the mammalian ATRX protein localizes to heterochromatin, Drosophila XNP is not a general component of heterochromatin. Instead, XNP localizes to active genes and to a major focus near the heterochromatin of the X chromosome. The XNP focus corresponds to an unusual decondensed satellite DNA block, and both active genes and the XNP focus are sites of ongoing nucleosome replacement. We suggest that the XNP remodeler modulates nucleosome dynamics at its target sites to limit chromatin accessibility. Although XNP at active genes may contribute to gene silencing, we find that a single focus is present across Drosophila species and that perturbation of this site cripples heterochromatic gene silencing. Thus, the XNP focus appears to be a functional genetic element that can contribute to gene silencing throughout the nucleus.heterochromatin ͉ nucleosome dynamics ͉ chromatin remodelers C hromatin in the eukaryotic nucleus consists of DNA wrapped around histone octamers into nucleosomes. Cytological and molecular features distinguish different kinds of chromatin within the nucleus (1). Gene-rich regions are usually packaged into euchromatin, which is decondensed in interphase nuclei, enriched for histone modifications associated with transcriptional activity, and often has high DNA accessibility. In contrast, gene-poor and repetitive sequences are packaged into heterochromatin, a condensed, relatively inaccessible chromatin organization that carries histone modifications associated with transcriptional repression.The genetic phenomenon of position effect variegation first indicated that heterochromatin could affect gene activity (2). Heterochromatic gene silencing has served as a sensitive measure to identify mutations in components of chromatin-based regulation (3, 4). Transcriptional repression in heterochromatin is thought to be crucial to limit the accumulation of transposable elements and unstable repetitive sequences in genomes.A major class of factors involved in altering chromatin structure is the SNF2-type chromatin remodelers (named after the founding sucrose nonfermenting 2 protein in Saccharomyces cerevisiae) (5). These nuclear enzymes use the energy of ATP binding and hydrolysis to manipulate histone-DNA contacts in nucleosomes. Individual remodelers also appear to differ in their activities; whereas some have been implicated in regulating promoter accessibility (6, 7), others are required ...

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“…Knowledge about this organism has consistently contributed to our understanding of human cell functions and diseases (Bier, 2005;Bilen and Bonini, 2005 Drosophila genetic screens over the years accumulated a library of more than 100 mutations that perturb heterochromatin-mediated silencing; some of these mutations regulate heterochromatin function and formation (Donaldson et al, 2002;Grigliatti, 1991;Reuter and Spierer, 1992;Reuter et al, 1982).…”

Section: Thesis Overviewmentioning

confidence: 99%

Local chromatin structure of heterochromatin regulates repeated DNA stability, nucleolus structure, and genome integrity

Peng

2007

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Local chromatin structure in heterochromatin regulates repeated DNA stability, nucleolus structure, and genome integrity by Jamy C. Peng Doctor of Philosophy in Molecular and Cell BiologyUniversity of California, BerkeleyProfessor Gary H. Karpen, ChairHeterochromatin constitutes a significant portion of the genome in higher eukaryotes; approximately 30% in Drosophila and human. Heterochromatin contains a high repeat DNA content and a low density of protein-encoding genes.In contrast, euchromatin is composed mostly of unique sequences and contains the majority of single-copy genes. Genetic and cytological studies demonstrated that heterochromatin exhibits regulatory roles in chromosome organization, centromere function and telomere protection.As an epigenetically regulated structure, heterochromatin formation is not defined by any DNA sequence consensus. Heterochromatin is characterized by its association with nucleosomes containing methylated-lysine 9 of histone H3 (H3K9me), heterochromatin protein 1 (HP1) that binds H3K9me, and Su(var)3-9, which methylates H3K9 and binds HP1. Heterochromatin formation and functions are influenced by HP1, Su(var)3-9, and the RNA interference (RNAi) pathway.

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Mutants affecting position-effect heterochromatinization in Drosophila melanogaster

Cited by 72 publications

References 14 publications

Identification of a nonhistone chromosomal protein associated with heterochromatin in Drosophila melanogaster and its gene.

Identification of a nonhistone chromosomal protein associated with heterochromatin in Drosophila melanogaster and its gene.

The XNP remodeler targets dynamic chromatin in Drosophila

Local chromatin structure of heterochromatin regulates repeated DNA stability, nucleolus structure, and genome integrity

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