Telomeric Repeat-Containing RNA (TERRA) and Human Diseases

Telomeres are the physical ends of linear chromosomes that maintain chromosomal stability. Loss of telomere function can lead to decrease in replication capacity, cellular senescence and progeria syndromes. In addition, cancer can be developed as a result of the genomic instability associated with telomere dysfunction. Till now, two types of telomere maintenance mechanism (TMM) have been known. The only two telomere maintenance mechanisms that have been described in mammalian cells are an enzymatic method that employs telomerase and recombination-based alternative lengthening of telomeres (ALT). In neoplasia, telomere maintenance mechanisms can be prognostic and may direct therapy in the future. Recently, a class of noncoding telomeric repeat-containing RNA (TERRA or TelRNA) transcripts has been transcribed from telomeres. Generally, increased TERRA transcription is associated with telomere shortening. In this review, we briefly evaluated the general principles behind telomere dysfunction. Moreover, the relationship between TERRA and disease has been described. Finally, TERRA potential in therapeutic approaches associated with defects in telomere function is studied.