共查询到20条相似文献,搜索用时 15 毫秒
1.
Chromosomal distribution of heterochromatin protein 1 (HP1) in Drosophila: a cytological map of euchromatic HP1 binding sites 总被引:2,自引:0,他引:2
The Heterochromatin Protein 1 (HP1) is a conserved protein which is best known for its strong association with the heterochromatin of Drosophila melanogaster. We previously demonstrated that another important property of HP1 is its localization to the telomeres of Drosophila, a feature that reflects its critical function as a telomere capping protein. Here we report our analysis of the euchromatic sites to which HP1 localizes. Using an anti-HP1 antibody, we compared immunostaining patterns on polytene chromosomes of the Ore-R wild type laboratory strain and four different natural populations. HP1 was found to accumulate at specific euchromatic sites, with a subset of the sites conserved among strains. These sites do not appear to be defined by an enrichment of known repetitive DNAs. Comparisons of HP1 patterns among several Drosophila species revealed that association with specific euchromatic regions, heterochromatin and telomeres is a conserved characteristic of HP1. Based on these results, we argue that HP1 serves a broader function than typically postulated. In addition to its role in heterochromatin assembly and telomere stability, we propose that HP1 plays an important role in regulating the expression of many different euchromatic regions. 相似文献
2.
3.
4.
The Paf1 complex factors Leo1 and Paf1 promote local histone turnover to modulate chromatin states in fission yeast
下载免费PDF全文
![点击此处可从《EMBO reports》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The maintenance of open and repressed chromatin states is crucial for the regulation of gene expression. To study the genes involved in maintaining chromatin states, we generated a random mutant library in Schizosaccharomyces pombe and monitored the silencing of reporter genes inserted into the euchromatic region adjacent to the heterochromatic mating type locus. We show that Leo1–Paf1 [a subcomplex of the RNA polymerase II‐associated factor 1 complex (Paf1C)] is required to prevent the spreading of heterochromatin into euchromatin by mapping the heterochromatin mark H3K9me2 using high‐resolution genomewide ChIP (ChIP–exo). Loss of Leo1–Paf1 increases heterochromatin stability at several facultative heterochromatin loci in an RNAi‐independent manner. Instead, deletion of Leo1 decreases nucleosome turnover, leading to heterochromatin stabilization. Our data reveal that Leo1–Paf1 promotes chromatin state fluctuations by enhancing histone turnover. 相似文献
5.
We have investigated the distribution of three heterochromatic proteins [SUppressor of UnderReplication (SUUR), heterochromatin protein 1 (HP1), and SU(VAR)3–9] in chromosomes of nurse cells (NCs) and have compared the data obtained with the distribution of the same proteins in salivary gland (SG) chromosomes. In NC chromosomes, the SU(VAR)3–9 protein was found in pericentric heterochromatin and at 223 sites on euchromatic arms, while in SG chromosomes, it was mainly restricted to the chromocenter. In NC chromosomes, the HP1 and SUUR proteins bind to 331 and 256 sites, respectively, which are almost twice the number of sites in SG chromosomes. The distribution of the HP1 and SU(VAR)3–9 proteins depends on the SuUR gene. A mutation in this gene results in a dramatic decrease in the amount of SU(VAR)3–9 binding sites in autosomes. In the X chromosome, these sites are relocated in comparison to the SuUR
+, and their total number only varies slightly. HP1 binding sites are redistributed in chromosomes of SuUR mutants, and their overall number did not change as considerably as SU(VAR)3–9. These data together point to an interaction of these three proteins in Drosophila NC chromosomes.Electronic Supplementary Material Supplementary material is available for this article at. 相似文献
6.
The ability of a chimeric HP1-Polycomb (Pc) protein to bind both to heterochromatin and to euchromatic sites of Pc protein binding was exploited to detect stable protein-protein interactions in vivo. Previously, we showed that endogenous Pc protein was recruited to ectopic heterochromatic binding sites by the chimeric protein. Here, we examine the association of other Pc group (Pc-G) proteins. We show that Posterior sex combs (Psc) protein also is recruited to heterochromatin by the chimeric protein, demonstrating that Psc protein participates in direct protein-protein interaction with Pc protein or Pc-associated protein. In flies carrying temperature-sensitive alleles of Enhancer of zeste[E(z)] the general decondensation of polytene chromosomes that occurs at the restrictive temperature is associated with loss of binding of endogenous Pc and chimeric HP1-Polycomb protein to euchromatin, but binding of HP1 and chimeric HP1-Polycomb protein to the heterochromatin is maintained. The E(z) mutation also results in the loss of chimera-dependent binding to heterochromatin by endogenous Pc and Psc proteins at the restrictive temperature, suggesting that interaction of these proteins is mediated by E(z) protein. A myc-tagged full-length Suppressor 2 of zeste [Su(z)2] protein interacts poorly or not at all with ectopic Pc-G complexes, but a truncated Su(z)2 protein is strongly recruited to all sites of chimeric protein binding. Trithorax protein is not recruited to the heterochromatin by the chimeric HP1-Polycomb protein, suggesting either that this protein does not interact directly with Pc-G complexes or that such interactions are regulated. Ectopic binding of chimeric chromosomal proteins provides a useful tool for distinguishing specific protein-protein interactions from specific protein-DNA interactions important for complex assembly in vivo. 相似文献
7.
8.
9.
Silvia Bongiorni Margherita Pugnali Silvia Volpi Davide Bizzaro Prim B. Singh Giorgio Prantera 《Chromosoma》2009,118(4):501-512
The establishment of sex-specific epigenetic marks during gametogenesis is one of the key feature of genomic imprinting. By
immunocytological analysis, we thoroughly characterized the chromatin remodeling events that take place during gametogenesis
in the mealybug Planococcus citri, in which an entire haploid set of (imprinted) chromosomes undergoes facultative heterochromatinization in male embryos.
Building on our previous work, we have investigated the interplay of several epigenetic marks in the regulation of this genome-wide
phenomenon. We characterized the germline patterns of histone modifications, Me(3)K9H3, Me(2)K9H3, and Me(3)K20H4, and of
heterochromatic proteins, PCHET2 (HP1-like) and HP2-like during male and female gametogenesis. We found that at all stages
in oogenesis chromatin is devoid of any detectable epigenetic marks. On the other hand, spermatogenesis is accompanied by
a complex pattern of redistribution of epigenetic marks from euchromatin to heterochromatin, and vice versa. At the end of
spermatogenesis, sperm heads are decorated by all the molecules we tested, except for PCHET2. However, only Me(3)K9H3 and
Me(2)K9H3 are still detectable in the male pronucleus. We suggest that the histone H3 lysine 9 methylation is the signal used
to establish the male-specific imprinting on the paternal genome, thus allowing it to be distinguished from the maternal genome
in the developing embryo.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
Heterochromatin Protein 1 (HP1a) Positively Regulates Euchromatic Gene Expression through RNA Transcript Association and Interaction with hnRNPs in Drosophila
下载免费PDF全文
![点击此处可从《PLoS genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lucia Piacentini Laura Fanti Rodolfo Negri Valerio Del Vescovo Alessandro Fatica Fabio Altieri Sergio Pimpinelli 《PLoS genetics》2009,5(10)
11.
cis-Acting determinants of heterochromatin formation on Drosophila melanogaster chromosome four
下载免费PDF全文
![点击此处可从《Molecular and cellular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sun FL Haynes K Simpson CL Lee SD Collins L Wuller J Eissenberg JC Elgin SC 《Molecular and cellular biology》2004,24(18):8210-8220
The heterochromatic domains of Drosophila melanogaster (pericentric heterochromatin, telomeres, and the fourth chromosome) are characterized by histone hypoacetylation, high levels of histone H3 methylated on lysine 9 (H3-mK9), and association with heterochromatin protein 1 (HP1). While the specific interaction of HP1 with both H3-mK9 and histone methyltransferases suggests a mechanism for the maintenance of heterochromatin, it leaves open the question of how heterochromatin formation is targeted to specific domains. Expression characteristics of reporter transgenes inserted at different sites in the fourth chromosome define a minimum of three euchromatic and three heterochromatic domains, interspersed. Here we searched for cis-acting DNA sequence determinants that specify heterochromatic domains. Genetic screens for a switch in phenotype demonstrate that local deletions or duplications of 5 to 80 kb of DNA flanking a transposon reporter can lead to the loss or acquisition of variegation, pointing to short-range cis-acting determinants for silencing. This silencing is dependent on HP1. A switch in transgene expression correlates with a switch in chromatin structure, judged by nuclease accessibility. Mapping data implicate the 1360 transposon as a target for heterochromatin formation. We propose that heterochromatin formation is initiated at dispersed repetitive elements along the fourth chromosome and spreads for approximately 10 kb or until encountering competition from a euchromatic determinant. 相似文献
12.
Heterochromatin protein 1 binds transgene arrays 总被引:7,自引:0,他引:7
Laura Fanti Douglas R. Dorer Maria Berloco Steven Henikoff Sergio Pimpinelli 《Chromosoma》1998,107(5):286-292
Heterochromatin protein 1 (HP1) of Drosophila and its homologs in vertebrates are key components of constitutive heterochromatin. Here we provide cytological evidence
for the presence of heterochromatin within a euchromatic chromosome arm by immunolocalization of HP1 to the site of a silenced
transgene repeat array. The amount of HP1 associated with arrays in polytene chromosomes is correlated with the array size.
Inverted transposons within an array or increased proximity of an array to blocks of naturally occurring heterochromatin may
increase transgene silencing without increasing HP1 labeling. Less dense anti-HP1 labeling is found at transposon arrays in
which there is no transgene silencing. The results indicate that HP1 targets the chromatin of transposon insertions and binds
more densely at a site with repeated sequences susceptible to heterochromatin formation.
Received: 26 June 1998; in revised form: 6 July 1998 / Accepted: 12 July 1998 相似文献
13.
14.
Li Y Danzer JR Alvarez P Belmont AS Wallrath LL 《Development (Cambridge, England)》2003,130(9):1817-1824
Heterochromatin protein 1 (HP1) is a conserved non-histone chromosomal protein enriched in heterochromatin. On Drosophila polytene chromosomes, HP1 localizes to centric and telomeric regions, along the fourth chromosome, and to specific sites within euchromatin. HP1 associates with centric regions through an interaction with methylated lysine nine of histone H3, a modification generated by the histone methyltransferase SU(VAR)3-9. This association correlates with a closed chromatin configuration and silencing of euchromatic genes positioned near heterochromatin. To determine whether HP1 is sufficient to nucleate the formation of silent chromatin at non-centric locations, HP1 was tethered to sites within euchromatic regions of Drosophila chromosomes. At 25 out of 26 sites tested, tethered HP1 caused silencing of a nearby reporter gene. The site that did not support silencing was upstream of an active gene, suggesting that the local chromatin environment did not support the formation of silent chromatin. Silencing correlated with the formation of ectopic fibers between the site of tethered HP1 and other chromosomal sites, some containing HP1. The ability of HP1 to bring distant chromosomal sites into proximity with each other suggests a mechanism for chromatin packaging. Silencing was not dependent on SU(VAR)3-9 dosage, suggesting a bypass of the requirement for histone methylation. 相似文献
15.
Jiří Bu Irma Ebert Monica Ruffini-Castiglione Jiří Široký Boris Vyskot Johann Greilhuber 《Planta》1998,204(4):506-514
Pentaploid endosperm nuclei in certain Gagea species exhibit large masses of sticky and dense chromatin, not observed in somatic nuclei. These heterochromatin masses
most probably stem from the triploid chalasal polar nucleus of the embryo sac, thus representing an example of facultative
heterochromatinisation in plants. In the present investigation, we studied the nuclei in Gagea lutea (L.) Ker-Gawl. endosperm tissue. The position of the heterochromatin in interphase nuclei was observed by confocal laser scanning
microscopy (CLSM) and the DNA methylation status of the euchromatin and heterochromatin was analysed by immunolabelling with
an antibody raised against 5-methylcytosine (anti-5-mC). In young endosperms, heterochromatin was relatively dispersed, occupying
some peripheral and inner parts of the nuclei. In a later endosperm development, the nuclei became smaller and more pycnotic,
and the heterochromatin masses were placed predominantly near the nuclear periphery. The distribution of anti-5-mC labelling
on the heterochromatic regions was unequal: some parts appeared hypermethylated while other parts were, like the euchromatin,
not labelled. During mitosis, the labelling intensity of all the chromosomes was approximately the same, thus indicating that
there are no cytologically detectable methylation differences among the individual sets of chromosomes. However, differences
in the anti-5-mC signal intensity along individual chromosomes were observed, resulting in banding patterns with highly positive
bands apparently representing constitutive heterochromatic regions. From these results it is obvious that facultative heterochromatinisation,
in contrast to constitutive heterochromatinisation, need not be strictly accompanied by a prominent DNA hypermethylation.
Received: 24 April 1997 / Accepted: 28 July 1997 相似文献
16.
Slawson EE Shaffer CD Malone CD Leung W Kellmann E Shevchek RB Craig CA Bloom SM Bogenpohl J Dee J Morimoto ET Myoung J Nett AS Ozsolak F Tittiger ME Zeug A Pardue ML Buhler J Mardis ER Elgin SC 《Genome biology》2006,7(2):R15-18
Background
Chromosome four of Drosophila melanogaster, known as the dot chromosome, is largely heterochromatic, as shown by immunofluorescent staining with antibodies to heterochromatin protein 1 (HP1) and histone H3K9me. In contrast, the absence of HP1 and H3K9me from the dot chromosome in D. virilis suggests that this region is euchromatic. D. virilis diverged from D. melanogaster 40 to 60 million years ago.Results
Here we describe finished sequencing and analysis of 11 fosmids hybridizing to the dot chromosome of D. virilis (372,650 base-pairs) and seven fosmids from major euchromatic chromosome arms (273,110 base-pairs). Most genes from the dot chromosome of D. melanogaster remain on the dot chromosome in D. virilis, but many inversions have occurred. The dot chromosomes of both species are similar to the major chromosome arms in gene density and coding density, but the dot chromosome genes of both species have larger introns. The D. virilis dot chromosome fosmids have a high repeat density (22.8%), similar to homologous regions of D. melanogaster (26.5%). There are, however, major differences in the representation of repetitive elements. Remnants of DNA transposons make up only 6.3% of the D. virilis dot chromosome fosmids, but 18.4% of the homologous regions from D. melanogaster; DINE-1 and 1360 elements are particularly enriched in D. melanogaster. Euchromatic domains on the major chromosomes in both species have very few DNA transposons (less than 0.4 %).Conclusion
Combining these results with recent findings about RNAi, we suggest that specific repetitive elements, as well as density, play a role in determining higher-order chromatin packaging. 相似文献17.
18.
The Genetic Identification of a Heterochromatic Segment on the X Chromosome of DROSOPHILA MELANOGASTER 总被引:8,自引:6,他引:2
下载免费PDF全文
![点击此处可从《Genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An autosomal euchromatic maternal-effect mutant, abo (= abnormal oocyte), interacts with, or regulates the activity of, the heterochromatin of the sex chromosomes of Drosophila melanogaster. It is shown that this interaction or regulation with the X chromosome involves a specific heterochromatic locus or small region that maps to the distal penultimate one-eighth of the basal X-chromosome heterochromatic segment. 相似文献
19.
The Drosophila melanogasterspecies subgroup is a closely-knit collection of eight sibling species whose relationships are well defined. These species
are too close for most evolutionary studies of euchromatic genes but are ideal to investigate the major changes that occur
to DNA in heterochromatin over short periods during evolution. For example, it is not known whether the locations of genes
in heterochromatin are conserved over this time. The 18S and 28S ribosomal RNA genes can be considered as genuine heterochromatic
genes. In D. melanogasterthe rRNA genes are located at two sites, one each on the X and Y chromosome. In the other seven sibling species, rRNA genes
are also located on the sex chromosomes but the positions often vary significantly, particularly on the Y. Furthermore, rDNA
has been lost from the Y chromosome of both D. simulansand D. sechellia, presumably after separation of the line leading to present-day D. mauritiana.We conclude that changes to chromosomal position and copy number of rDNA arrays occur over much shorter evolutionary timespans
than previously thought. In these respects the rDNA behaves more like the tandemly repeated satellite DNAs than euchromatic
genes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.