HP1 Controls Telomere Capping, Telomere Elongation, and Telomere Silencing by Two Different Mechanisms in Drosophila

Perrini, Barbara; Piacentini, Lucia; Fanti, Laura; Altieri, Fabio; Chichiarelli, Silvia; Berloco, Maria; Turano, Carlo; Ferraro, Anna; Pimpinelli, Sergio

doi:10.1016/j.molcel.2004.06.036

Cited by 158 publications

(186 citation statements)

References 59 publications

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“…This protein also appears to provide a capping function at the very ends of chromosomes (Fanti et al 1998;Perrini et al 2004). The depletion of HP1 that occurs in stocks heterozygous for a Su(var)205 mutation allows retrotransposons to attach frequently to chromosome ends (Savitsky et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Cytotype Regulation by TelomericPElements inDrosophila melanogaster: Evidence for Involvement of an RNA Interference Gene

et al. 2007

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P elements inserted at the left telomere of the X chromosome evoke the P cytotype, a maternally inherited condition that regulates the P-element family in the Drosophila germline. This regulation is completely disrupted in stocks heterozygous for mutations in aubergine, a gene whose protein product is involved in RNA interference. However, cytotype is not disrupted in stocks heterozygous for mutations in two other RNAi genes, piwi and homeless (spindle-E ), or in a stock heterozygous for a mutation in the chromatin protein gene Enhancer of zeste. aubergine mutations exert their effects in the female germline, where the P cytotype is normally established and through which it is maintained. These effects are transmitted maternally to offspring of both sexes independently of the mutations themselves. Lines derived from mutant aubergine stocks reestablish the P cytotype quickly, unlike lines derived from stocks heterozygous for a mutation in Suppressor of variegation 205, the gene that encodes the telomere-capping protein HP1. Cytotype regulation by telomeric P elements may be tied to a system that uses RNAi to regulate the activities of telomeric retrotransposons in Drosophila.

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Section: Discussionmentioning

confidence: 99%

Cytotype Regulation by TelomericPElements inDrosophila melanogaster: Evidence for Involvement of an RNA Interference Gene

et al. 2007

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“…The HP1 protein has been reported to play a role in telomere capping, elongation, and HeT-A transcription (Savitsky et al 2002;Perrini et al 2004). The mechanism by which HP1 might act to promote HeT-A transcription and elongation is unclear, as it is not possible to estimate the number of transcripts per genomic HeT-A copy number, because both increase in the presence of a mutation in Su(var)205.…”

Section: Discussionmentioning

confidence: 99%

Two Distinct Domains in Drosophila melanogaster Telomeres

et al. 2005

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Telomeres are generally considered heterochromatic. On the basis of DNA composition, the telomeric region of Drosophila melanogaster contains two distinct subdomains: a subtelomeric region of repetitive DNA, termed TAS, and a terminal array of retrotransposons, which perform the elongation function instead of telomerase. We have identified several P-element insertions into this retrotransposon array and compared expression levels of transgenes with similar integrations into TAS and euchromatic regions. In contrast to insertions in TAS, which are silenced, reporter genes in the terminal HeT-A, TAHRE, or TART retroelements did not exhibit repressed expression in comparison with the same transgene construct in euchromatin. These data, in combination with cytological studies, provide evidence that the subtelomeric TAS region exhibits features resembling heterochromatin, while the terminal retrotransposon array exhibits euchromatic characteristics. D NA sequences at the ends of eukaryotic chromosomes are the products of a telomere elongation process. In most eukaryotes, these sequences are simple repeating units that are synthesized by telomerase, but in Drosophila melanogaster they are tandem head-to-tail arrays of three non-long terminal repeat retrotransposons, HeT-A, TAHRE, and TART ( Despite these differences, a common feature of eukaryotic chromosomes is a region of complex repeats located adjacent to the terminal sequences. These complex repeats are referred to as subtelomeric regions, or telomere-associated sequences (TAS), and differ in sequence, structure, and length among species and among telomeres within an individual (Pryde et al. 1997). The repetitive nature and the high density of transposable elements in these subtelomeric regions (Mefford and Trask 2002) are reminiscent of heterochromatin. In D. melanogaster, TAS consist of several kilobases of complex repeats, which exhibit similarities between the different chromosome ends. Sequences of the 2L and X TAS regions have been described in detail (Karpen and Spradling 1992;Walter et al. 1995), and in situ hybridizations to polytene chromosomes showed that 2L TAS share homology with 3L TAS, while X TAS share homology with 2R and 3R TAS. The 2L TAS appear to be 15 kb in length and composed of relatively simple

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“…On one hand, su(var)2-5 mutants show much stronger effects than either woc or row mutants (Fanti et al 1998;Raffa et al 2005). Furthermore, both telomere length and expression of the telomeric retrotransposons Het-A and TART are increased in su-(var)2-5 mutants, but they are not affected in woc-null mutants (Perrini et al 2004;Raffa et al 2005). In addition, expression profiling data show that, in hp1c RNAi , woc RNAi , and row RNAi mutants, expression of Het-A and TART is not significantly affected (data not shown).…”

Section: Hp1c and Telomere Functionmentioning

confidence: 96%

Drosophila HP1c isoform interacts with the zinc-finger proteins WOC and Relative-of-WOC to regulate gene expression

Font-Burgada¹,

Rossell²,

Auer³

et al. 2008

Genes Dev.

129

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Heterochromatin protein 1 (HP1) proteins are conserved in eukaryotes, with most species containing several isoforms. Based on the properties of Drosophila HP1a, it was proposed that HP1s bind H3K9me2,3 and recruit factors involved in heterochromatin assembly and silencing. Yet, it is unclear whether this general picture applies to all HP1 isoforms and functional contexts. Here, we report that Drosophila HP1c regulates gene expression, as (1) it localizes to active chromatin domains, where it extensively colocalizes with the poised form of RNApolymerase II (RNApol II), Pol IIo ser5 , and H3K4me3, suggesting a contribution to transcriptional regulation; (2) its targeting to a reporter gene does not induce silencing but, on the contrary, increases its expression, and (3) it interacts with the zinc-finger proteins WOC (without children) and Relative-of-WOC (ROW), which are putative transcription factors. Here, we also show that, although HP1c efficiently binds H3K9me2,3 in vitro, its binding to chromatin strictly depends on both WOC and ROW. Moreover, expression profiling indicates that HP1c, WOC, and ROW regulate a common gene expression program that, in part, is executed in the context of the nervous system. From this study, which unveils the essential contribution of DNA-binding proteins to HP1c functionality and recruitment, HP1 proteins emerge as an increasingly diverse family of chromatin regulators.[Keywords: HP1; WOC; ROW/CG8092; chromatin; Drosophila] Supplemental material is available at http://www.genesdev.org.

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HP1 Controls Telomere Capping, Telomere Elongation, and Telomere Silencing by Two Different Mechanisms in Drosophila

Cited by 158 publications

References 59 publications

Cytotype Regulation by TelomericPElements inDrosophila melanogaster: Evidence for Involvement of an RNA Interference Gene

Cytotype Regulation by TelomericPElements inDrosophila melanogaster: Evidence for Involvement of an RNA Interference Gene

Two Distinct Domains in Drosophila melanogaster Telomeres

Drosophila HP1c isoform interacts with the zinc-finger proteins WOC and Relative-of-WOC to regulate gene expression

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