Oxidative stress induces the expression of telomeric repeat-containing RNA

A. M. CABANILLAS; G. PIWIEN PILIPUK; N.M. GALIGNIANA; N. CHARÓ

Turku

Congreso; The 8th International Congress on Stress Proteins in Biology and Medicine; 2017

International Cell Stress Society

Telomeres are nucleoprotein complexes at the end of linear chromosomes essential for chromosome stability, and they can be transcribed in response to developmental changes and in tumor cells. These transcripts are known as telomeric repeat-containing RNA (TERRA). Increasing oxidative stress and inflammation enhance the process of erosion of telomeres with each cycle of replication. In fact, the G-rich telomeric sequence is more susceptible to acute oxidative damage, compared with genomic DNA. However, little is known about how this affects TERRA levels. Since oxidative stress is known to disrupt cytoskeleton integrity and mechanical cues are important regulators of transcriptional programs, our objective was to characterize TERRA levels using different oxidizing agents and to evaluate the possible role of microtubules in this process. We found that human embryonic kidney HEK-293T cells undergo induction of TERRAs after 4h treatment with H2O2, sodium arsenite or buthionine-sulfoximine, which is prevented by antioxidant treatment with N-acetyl-L-cysteine. TERRA induction is mimicked by microtubule disruption using colcemid. Interestingly, microtubule stabilization using taxol also resulted in TERRA induction, suggesting that a delicate mechanotransduction mechanism is involved in TERRA regulation. Cell fractionation experiments showed that TERRAs localize in both nuclear and cytosolic compartments, contrary to classical belief. Nevertheless, TERRA induction was only observed in the nuclear fraction, implying that only the nucleus seems to harbor the newly transcribed TERRAs in response to H2O2 treatment. These results indicate that the nuclear functions of TERRAs may be essential in the response of HEK-293T cells to oxidative stress caused by H2O2 exposure, possibly in order to contribute to telomere integrity and, hence, genome stability.