Promoting transcription of chromosome ends

Farnung, Benjamin O.; Giulotto, Elena; Azzalin, Claus M.

doi:10.4161/trns.1.3.13191

Cited by 18 publications

(17 citation statements)

References 28 publications

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“…In mammals, TERRA transcripts originating from regulated promoters consist of UUAGGG repeated sequence and a subtelomeric sequence [46]. TERRA are proposed to take part in heterochromatinization of telomere regions by RNAi mechanism and to form quadruplex structures that stabilize telomere.…”

Section: Discussionmentioning

confidence: 99%

Cytological maps of lampbrush chromosomes of European water frogs (Pelophylax esculentuscomplex) from the Eastern Ukraine

et al. 2013

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BackgroundHybridogenesis (hemiclonal inheritance) is a kind of clonal reproduction in which hybrids between parental species are reproduced by crossing with one of the parental species. European water frogs (Pelophylax esculentus complex) represent an appropriate model for studying interspecies hybridization, processes of hemiclonal inheritance and polyploidization. P. esculentus complex consists of two parental species, P. ridibundus (the lake frog) and P. lessonae (the pool frog), and their hybridogenetic hybrid – P. esculentus (the edible frog). Parental and hybrid frogs can reproduce syntopically and form hemiclonal population systems. For studying mechanisms underlying the maintenance of water frog population systems it is required to characterize the karyotypes transmitted in gametes of parental and different hybrid animals of both sexes.ResultsIn order to obtain an instrument for characterization of oocyte karyotypes in hybrid female frogs, we constructed cytological maps of lampbrush chromosomes from oocytes of both parental species originating in Eastern Ukraine. We further identified certain molecular components of chromosomal marker structures and mapped coilin-rich spheres and granules, chromosome associated nucleoli and special loops accumulating splicing factors. We recorded the dissimilarities between P. ridibundus and P. lessonae lampbrush chromosomes in the length of orthologous chromosomes, number and location of marker structures and interstitial (TTAGGG)n-repeat sites as well as activity of nucleolus organizer. Satellite repeat RrS1 was mapped in centromere regions of lampbrush chromosomes of the both species. Additionally, we discovered transcripts of RrS1 repeat in oocytes of P. ridibundus and P. lessonae. Moreover, G-rich transcripts of telomere repeat were revealed in association with terminal regions of P. ridibundus and P. lessonae lampbrush chromosomes.ConclusionsThe constructed cytological maps of lampbrush chromosomes of P. ridibundus and P. lessonae provide basis to define the type of genome transmitted within individual oocytes of P. esculentus females with different ploidy and from various population systems.

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Section: Discussionmentioning

confidence: 99%

Cytological maps of lampbrush chromosomes of European water frogs (Pelophylax esculentuscomplex) from the Eastern Ukraine

et al. 2013

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“…29–37 repeats are preceded by tandemly repeated 61 bp units that are dispensable for promoter activity and of so far uncharacterized function [8], [9]. CpG dinucleotides within TERRA promoters are heavily methylated in different cancer and primary cells [9].…”

Section: Introductionmentioning

confidence: 99%

Telomerase Efficiently Elongates Highly Transcribing Telomeres in Human Cancer Cells

et al. 2012

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RNA polymerase II transcribes the physical ends of linear eukaryotic chromosomes into a variety of long non-coding RNA molecules including telomeric repeat-containing RNA (TERRA). Since TERRA discovery, advances have been made in the characterization of TERRA biogenesis and regulation; on the contrary its associated functions remain elusive. Most of the biological roles so far proposed for TERRA are indeed based on in vitro experiments carried out using short TERRA-like RNA oligonucleotides. In particular, it has been suggested that TERRA inhibits telomerase activity. We have exploited two alternative cellular systems to test whether TERRA and/or telomere transcription influence telomerase-mediated telomere elongation in human cancer cells. In cells lacking the two DNA methyltransferases DNMT1 and DNMT3b, TERRA transcription and steady-state levels are greatly increased while telomerase is able to elongate telomeres normally. Similarly, telomerase can efficiently elongate transgenic inducible telomeres whose transcription has been experimentally augmented. Our data challenge the current hypothesis that TERRA functions as a general inhibitor of telomerase and suggest that telomere length homeostasis is maintained independently of TERRA and telomere transcription.

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“…In human cells, TERRA is transcribed from CpG-island promoters whose methylation levels influence TERRA expression; such promoters are located on 20 subtelomeres (Nergadze et al, 2009; Farnung et al, 2010). Although these observations suggest that TERRA may play a role, specific functions still remain to be assigned to this non-coding RNA fraction.…”

Section: Introductionmentioning

confidence: 99%

TERRA Expression Levels Do Not Correlate with Telomere Length and Radiation Sensitivity in Human Cancer Cell Lines

Smirnova¹,

Gamba²,

Khoriauli³

et al. 2013

Front. Oncol.

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Mammalian telomeres are transcribed into long non-coding telomeric repeat-containing RNA (TERRA) molecules that seem to play a role in the maintenance of telomere stability. In human cells, CpG-island promoters drive TERRA transcription and are regulated by methylation. It was suggested that the amount of TERRA may be related to telomere length. To test this hypothesis we measured telomere length and TERRA levels in single clones isolated from five human cell lines: HeLa (cervical carcinoma), BRC-230 (breast cancer), AKG and GK2 (gastric cancers), and GM847 (SV40 immortalized skin fibroblasts). However, these two parameters did not correlate with each other. Moreover, cell survival to γ-rays did not show a significant variation among the clones, suggesting that, in this cellular system, the intra-population variability in telomere length and TERRA levels does not influence sensitivity to ionizing radiation. This conclusion was supported by the observation that in a cell line in which telomeres were greatly elongated by the ectopic expression of telomerase, TERRA expression levels and radiation sensitivity were similar to the parental HeLa cell line.

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Promoting transcription of chromosome ends

Cited by 18 publications

References 28 publications

Cytological maps of lampbrush chromosomes of European water frogs (Pelophylax esculentuscomplex) from the Eastern Ukraine

Cytological maps of lampbrush chromosomes of European water frogs (Pelophylax esculentuscomplex) from the Eastern Ukraine

Telomerase Efficiently Elongates Highly Transcribing Telomeres in Human Cancer Cells

TERRA Expression Levels Do Not Correlate with Telomere Length and Radiation Sensitivity in Human Cancer Cell Lines

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