Abstract
Telomeric repeat-containing RNAs (TERRAs) are long noncoding RNAs transcribed from subtelomeres toward telomeric repeat tracts, which have been implicated in telomere protection and heterochromatin formation. Genotoxic stress leads to upregulation of TERRAs. However, the mechanism of DNA damage-mediated TERRA induction remains elusive. Here, we treated HeLa cells with etoposide, a DNA double-strand break-generating agent, for various times and monitored the levels of TERRAs. Etoposide treatment led to a gradual time-dependent increase in TERRAs. Etoposide-mediated induction was evident in many TERRAs arising from various chromosome loci, including 20q and XpYp. Chromatin immunoprecipitation assays revealed no significant changes in the occupancy of RNA polymerase II at telomeres upon etoposide treatment. Interestingly, TERRAs arising from 20q, XpYp, 10q, and 13q degraded at slower rates in cells treated with etoposide, while degradation rates of TERRAs from many loci tested were nearly identical in both etoposide- and mock-treated cells. Telomere damage occurred from early time points of etoposide treatment, but telomere lengths and abundance of telomeric repeat-binding factor 2 (TRF2) at telomeres remained unchanged. In summary, etoposide treatment led to telomere damage and TERRA accumulation, but telomere lengths and TRF2-mediated telomere integrity were maintained. Etoposide-mediated TERRA accumulation could be attributed partly to RNA stabilization. These findings may provide insight into the post-transcriptional regulation of TERRAs in response to DNA damage.
Highlights
Telomeres protect chromosome ends from DNA damage [1]
We examined the stability of Telomeric repeat-containing RNAs (TERRAs) and the telomerebinding activity of RNA polymerase II (RNAPII), which revealed that RNA stabilization accounted partly for the accumulation of TERRAs
We measured the levels of TERRAs using Reverse transcription quantitative polymerase chain reaction (RT–qPCR) and found that exposure of cells to etoposide led to progressive time-dependent increases in the levels of TERRAs
Summary
Telomeres protect chromosome ends from DNA damage [1]. Human telomeres are composed of tandem 50–TTAGGG–30 repeats and are bound by shelterin complexes composed of six proteins [2]. Telomeric repeat-binding factor 2 (TRF2), a component of shelterin, binds directly. TERRA accumulation and DNA damage data collection and analysis, decision to publish, or preparation of the manuscript
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