Oligonucleotide Models of Telomeric DNA and RNA Form a Hybrid G-quadruplex Structure as a Potential Component of Telomeres

Yan Xu,Takumi Ishizuka,Jie Yang,Kenichiro Ito,Hitoshi Katada,Makoto Komiyama,Tetsuya Hayashi

doi:10.1074/jbc.m112.342030

Yan Xu, Takumi Ishizuka + Show 5 more

Open Access

https://doi.org/10.1074/jbc.m112.342030

Copy DOI

Abstract

Telomeric repeat-containing RNA, a non-coding RNA molecule, has recently been found in mammalian cells. The detailed structural features and functions of the telomeric RNA at human chromosome ends remain unclear, although this RNA molecule may be a key component of the telomere machinery. In this study, using model human telomeric DNA and RNA sequences, we demonstrated that human telomeric RNA and DNA oligonucleotides form a DNA-RNA G-quadruplex. We next employed chemistry-based oligonucleotide probes to mimic the naturally formed telomeric DNA-RNA G-quadruplexes in living cells, suggesting that the process of DNA-RNA G-quadruplex formation with oligonucleotide models of telomeric DNA and RNA could occur in cells. Furthermore, we investigated the possible roles of this DNA-RNA G-quadruplex. The formation of the DNA-RNA G-quadruplex causes a significant increase in the clonogenic capacity of cells and has an effect on inhibition of cellular senescence. Here, we have used a model system to provide evidence about the formation of G-quadruplex structures involving telomeric DNA and RNA sequences that have the potential to provide a protective capping structure for telomere ends.

Highlights

Telomeric repeat-containing RNA has recently been found in mammalian cells
In this study, using model human telomeric DNA and RNA sequences, we demonstrated that human telomeric RNA and DNA oligonucleotides form a DNA-RNA G-quadruplex
We found that the human telomeric DNA-RNA G-quadruplex causes a significant increase in the clonogenic capacity of cells when exposed to an oligonucleotide (T-oligo) homologous to the telomeric 3Ј single-stranded overhang to activate DNA damage signals and induce senescence in cells

Summary

Background

Telomeric repeat-containing RNA has recently been found in mammalian cells. Results: Oligonucleotide models of telomeric DNA and RNA form a hybrid G-quadruplex structure. A profluorophore probe that resulted in a strong fluorescence by eliminating its fluorescence quenching was used to detect DNA-RNA G-quadruplex structures Using this probe, we found that the process of DNA-RNA G-quadruplex formation by oligonucleotide models of telomeric DNA and RNA could occur in cells. We demonstrated that the DNA-RNA G-quadruplex inhibits chromosome end fusions and has an effect on the inhibition of cellular senescence using the inhibition of telomeric repeat binding factor (TRF 2) by inducing a dominant negative allele of TRF 2 (TRF 2⌬B⌬M) These results suggest that the formation of the DNA-RNA G-quadruplex by telomeric RNA and DNA contributes to telomere end protection, providing valuable information for understanding the structure and function of human telomere DNA and RNA

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION