Nuclear induction of telomeric repeat containing RNA depends on microtubule stability under oxidative stress conditions

CHARO, N; GALIGNIANA, N; PIWIEN-PILIPUK, G; CABANILLAS, ANA MARIA

Mar del Plata

Congreso; Reunion anual SAIC SAI SAFE 2016; 2016

SAIC SAI SAFE

Telomeres are nucleoprotein complexes at the end of linear chromosomes essential forchromosome stability, and they can be transcribed in response to developmental changes andcellular stress conditions. These transcripts are known as telomeric repeat-containing RNA(TERRA). Increasing oxidative stress and inflammation enhance the process of erosion oftelomeres with each cycle of replication. In fact, the G-rich telomeric sequence is more susceptibleto acute oxidative damage, compared with genomic DNA. However, little is known about how thisaffects TERRA levels. Since oxidative stress is known to disrupt cytoskeleton integrity andmechanical cues are important regulators of transcriptional programs, our objective was tocharacterize TERRA levels using different oxidizing agents and to evaluate the possible role ofmicrotubules in this process. We previously found that human embryonic kidney HEK-293T cellsundergo induction of TERRAs after 4h treatment with H2O2, sodium arsenite or buthioninesulfoximine,which is prevented by antioxidant treatment with N-acetyl-L-cysteine. In the presentstudy, we show that TERRA induction is mimicked by microtubule disruption using colcemid.Interestingly, microtubule stabilization using taxol also resulted in TERRA induction, suggesting thata delicate mechanotransduction mechanism is involved in TERRA regulation. Cell fractionationexperiments 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.