2 research outputs found
Methylation of subtelomeric chromatin modifies the expression of the lncRNA TERRA, disturbing telomere homeostasis
The long noncoding RNA (lncRNA) telomeric repeat-containing RNA (TERRA) has been associated with telomeric homeostasis, telomerase recruitment, and the process of chromosome healing; nevertheless, the impact of this association has not been investigated during the carcinogenic process. Determining whether changes in TERRA expression are a cause or a consequence of cell transformation is a complex task because studies are usually carried out using either cancerous cells or tumor samples. To determine the role of this lncRNA in cellular aging and chromosome healing, we evaluated telomeric integrity and TERRA expression during the establishment of a clone of untransformed myeloid cells. We found that reduced expression of TERRA disturbed the telomeric homeostasis of certain loci, but the expression of the lncRNA was affected only when the methylation of subtelomeric bivalent chromatin domains was compromised. We conclude that the disruption in TERRA homeostasis is a consequence of cellular transformation and that changes in its expression profile can lead to telomeric and genomic instability
Proteasome inhibition alters mitotic progression through the upregulation of centromeric α-Satellite RNAs
Cell cycle progression requires control of the abundance of several proteins and RNAs over space and time to properly transit from one phase to the next and to ensure faithful genomic inheritance in daughter cells. The proteasome, the main protein degradation system of the cell, facilitates the establishment of a proteome specific to each phase of the cell cycle. Its activity also strongly influences transcription. Here, we detected the upregulation of repetitive RNAs upon proteasome inhibition in human cancer cells using RNAâseq. The effect of proteasome inhibition on centromeres was remarkable, especially on αâSatellite RNAs. We showed that αâSatellite RNAs fluctuate along the cell cycle and interact with members of the cohesin ring, suggesting that these transcripts may take part in the regulation of mitotic progression. Next, we forced exogenous overexpression and used gapmer oligonucleotide targeting to demonstrate that αâSat RNAs have regulatory roles in mitosis. Finally, we explored the transcriptional regulation of αâSatellite DNA. Through inâsilico analyses, we detected the presence of CCAAT transcription factorâbinding motifs within αâSatellite centromeric arrays. Using highâresolution threeâdimensional immunoâFISH and ChIPâqPCR, we showed an association between the αâSatellite upregulation and the recruitment of the transcription factor NFYâA to the centromere upon MG132âinduced proteasome inhibition. Together, our results show that the proteasome controls αâSatellite RNAs associated with the regulation of mitosis