Telomere Position Effect-Over Long Distances Acts as a Genome-Wide Epigenetic Regulator Through a Common Alu Element.

Among epigenetic modifiers, telomeres represent attractive modulators of the genome in part through position effects. Telomere Position Effect-Over Long Distances (TPE-OLD) modulates gene expression by changes in telomere-dependent long-distance loops. To gain insights into the molecular mechanisms of TPE-OLD, we performed a genome-wide transcriptome and methylome analysis in proliferative fibroblasts and myoblasts or differentiated myotubes with controlled telomere lengths. By integrating omics data, we identified a common TPE-OLD dependent cis-acting motif that behaves as an insulator or enhancer. Next, we uncovered trans partners that regulate these activities and observed the consistent depletion of one candidate factor, RBPJ, at TPE-OLD associated loci upon telomere shortening. Importantly, we confirmed our findings by unbiased comparisons to recent Human transcriptomic studies, including those from the Genotype-Tissue Expression (GTEx) project. We concluded that TPE-OLD acts at the genome-wide level and can be relayed by RBPJ bridging Alu-like elements to telomeres. In response to physiological (i.e., aging) or pathological cues, TPE-OLD might coordinate the genome-wide impact of telomeres through recently evolved Alu elements acting as enhancers in association with RBPJ.