Telomerase

Definition

Telomerase is an enzyme that adds repetitive nucleotide sequences to the ends of chromosomes, called telomeres, to prevent their shortening during DNA replication. This process is crucial for maintaining genomic stability and allows cells to divide without losing important genetic information. Telomerase plays a significant role in cellular aging, cancer biology, and the overall maintenance of chromosome integrity.

5 Must Know Facts For Your Next Test

1. Telomerase is active in stem cells and germ cells but is typically inactive in somatic cells, leading to progressive telomere shortening with each cell division.
2. In many cancer cells, telomerase is reactivated, allowing them to replicate indefinitely and contribute to tumor growth.
3. The enzyme consists of an RNA component that serves as a template for adding DNA repeats, along with a reverse transcriptase enzyme that synthesizes the new DNA.
4. Shortened telomeres are associated with aging and age-related diseases, making telomerase a potential target for therapies aimed at improving health span.
5. Research into telomerase inhibitors is ongoing as a strategy to combat cancer by limiting the replicative potential of malignant cells.

Review Questions

• How does telomerase contribute to cellular aging and its relationship with senescence?
  • Telomerase helps maintain telomere length, which is critical for preventing cellular aging. In normal somatic cells, telomerase activity is low or absent, resulting in progressive telomere shortening with each division. When telomeres become critically short, cells enter senescence, a state of irreversible growth arrest. Therefore, telomerase's role in maintaining telomere length directly impacts how cells age and when they stop dividing.
• Discuss the implications of telomerase reactivation in cancer cells and how it relates to DNA damage repair mechanisms.
  • In many cancer cells, telomerase is reactivated, which allows these cells to bypass normal limits on cell division imposed by short telomeres. This reactivation contributes to genomic instability because it can lead to unchecked cell proliferation and resistance to DNA damage. As a result, cancer cells can evade apoptosis and accumulate mutations that drive tumorigenesis, demonstrating how telomerase influences both DNA repair processes and cancer progression.
• Evaluate the potential therapeutic strategies targeting telomerase in relation to aging and cancer treatment.
  • Therapeutic strategies targeting telomerase involve either activating it in aging tissues to counteract cellular senescence or inhibiting it in cancer cells to limit their growth. By enhancing telomerase activity in normal cells, researchers hope to extend lifespan and improve health span by preventing age-related deterioration. Conversely, inhibiting telomerase in cancer could prevent tumors from maintaining their replicative immortality. Both approaches highlight the dual role of telomerase in promoting longevity in healthy tissues while also serving as a target for eliminating malignant cell growth.

Related terms

Telomeres: Telomeres are repetitive DNA sequences at the ends of chromosomes that protect them from degradation and fusion with other chromosomes.

DNA Replication: DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule, essential for cell division.

Senescence: Senescence is the process where cells permanently stop dividing and enter a state of growth arrest, often linked to telomere shortening.