Centromeres from telomeres? The centromeric region of the Y chromosome of Drosophila melanogaster contains a tandem array of telomeric HeT-A- and TART-related sequences

Agudo, Marta; Losada, Ana; Abad, José Pascual; Pimpinelli, Sergio; Ripóll, Pedro; Villasanté, Alfredo

doi:10.1093/nar/27.16.3318

Cited by 58 publications

(72 citation statements)

References 43 publications

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“…HeT-A, TAHRE, and TART sequences are predominantly found at telomeres, but tandem arrays of relatively short HeT-A segments also occur in autosomal centromeric heterochromatin and in interstitial regions of the heterochromatic Y chromosome (Young et al 1983;Traverse and Pardue 1989;Agudo et al 1999). Thus, isolation of HeT-A sequences from genomic DNA libraries does not ensure that the cloned fragments originated from a telomere (Biessmann et al 1993).…”

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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Section: Discussionmentioning

confidence: 99%

Two Distinct Domains in Drosophila melanogaster Telomeres

et al. 2005

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“…However, arrays of telomeric elements, decayed by numerous in/del mutations, have been found in centromeric and pericentromeric heterochromatin. [37][38][39][40][41][42][43] TART and TAHRE have the two open reading frames typical of non-LTR retrotransposons; the ORF1 encodes a putative RNA binding protein and the ORF2 encodes a protein with domains related to both reverse transcriptase (RT) and endonuclease. 31,32 Per contra, HeT-A is an atypical element because it lacks ORF2, so the RT for its transposition must be produced in trans.…”

Section: Three Retrotransposons Maintain Telomeres In Drosophila Melamentioning

confidence: 99%

Telomere maintenance in Drosophila: Rapid transposon evolution at chromosome ends

Villasanté

Pablos²,

Méndez-Lago³

et al. 2008

Cell Cycle

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The maintenance of terminal sequences is an important role of the telomere, since it prevents the loss of internal regions that encode essential genes. In most eukaryotes, this is accomplished by the telomerase. However, telomere length can also be maintained by other mechanisms, such as homologous recombination and transposition of telomeric retrotransposons to the chromosome ends. A remarkable situation is the case of Drosophila, where telomerase was lost, and thus telomeres managed to be maintained by occasional retrotransposition of telomeric elements to the receding ends. In the recent analysis of 12 Drosophila genomes, the multiplicity of autonomous and non-autonomous telomere-specific retrotransposons has revealed extensive and rapid evolution of telomeric DNA. The phylogenetic relationship among these telomeric retrotransposons is congruent with the species phylogeny, suggesting that they have been vertically transmitted from a common ancestor. In this review, we also suggest that the formation of a non-canonical DNA structure at Drosophila telomeres could be the way to protect the ends.

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“…In the Drosophila melanogaster genome, each centromeric region seems to contain different sets of satellite DNA sequences (Abad et al 1992(Abad et al , 2000Lohe et al 1993;Sun et al 1997;Agudo et al 1999;Lamb and Birchler 2003). The X chromosome contains a large block of complex 1.688 satellite DNA (359-bp repeat unit), located in the centromeric region and in the adjacent 1 pericentromeric heterochromatin (Lohe et al 1993;Abad et al 2000) (Figure 1A), and large autosomes contain arrays of different subfamilies of 1.688 satellite DNA in the pericentromeric heterochromatin.…”

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Transcription of the 1.688 Satellite DNA Family Is Under the Control of RNA Interference Machinery inDrosophila melanogasterOvaries

et al. 2007

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Here we show that RNA interference (RNAi) machinery operates in Drosophila melanogaster 1.688 satellite transcription. Mutation in the spn-E gene, known to be involved in RNAi in the oocytes, causes an increase of satellite transcript abundance. Transcripts of both strands of 1.688 satellite repeats in germinal tissues were detected. The strength of the effects of the spn-E mutation differs for 1.688 satellite DNA subfamilies and is more pronounced for autosomal pericentromeric satellites compared to the X-linked centromeric ones. The spn-E 1 mutation causes an increase of the H3-AcK9 mark and TAF1 (a component of the polymerase II transcriptional complex) occupancy in the chromatin of autosomal pericentromeric repeats. Thus, we revealed that RNAi operates in ovaries to maintain the silenced state of centromeric and pericentromeric 1.688 repeats.

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Centromeres from telomeres? The centromeric region of the Y chromosome of Drosophila melanogaster contains a tandem array of telomeric HeT-A- and TART-related sequences

Cited by 58 publications

References 43 publications

Two Distinct Domains in Drosophila melanogaster Telomeres

Two Distinct Domains in Drosophila melanogaster Telomeres

Telomere maintenance in Drosophila: Rapid transposon evolution at chromosome ends

Transcription of the 1.688 Satellite DNA Family Is Under the Control of RNA Interference Machinery inDrosophila melanogasterOvaries

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