Telomerase and Regeneration: A Mini-Review

Telomerase is a specialized enzyme that plays a crucial role in maintaining the stability and integrity of chromosomes. It is a ribonucleoprotein composed of a protein component with reverse transcriptase activity (TERT – Telomerase Reverse Transcriptase) and an RNA component (TERC), which serves as a template for adding repetitive DNA sequences. Telomerase primarily functions to elongate telomeres, the protective repetitive DNA sequences (TTAGGG in humans) located at the ends of linear chromosomes. Each time a cell divides, normal DNA replication machinery cannot fully replicate the ends of chromosomes, leading to progressive telomere shortening, which is associated with cellular aging and eventual senescence. Telomerase counteracts this shortening by adding telomeric repeats, thereby extending the lifespan of cells and maintaining genomic stability. Telomerase activity is typically high in germline cells, stem cells, and certain immune cells, allowing them to divide many times without losing vital genetic information. In contrast, most somatic (body) cells have very low or absent telomerase activity, which contributes to aging. Importantly, telomerase is also reactivated in most cancer cells, enabling them to bypass normal senescence and divide uncontrollably, which makes it a target for cancer research and therapeutic interventions.