Telomere shortening

Definition

Telomere shortening refers to the progressive loss of repetitive nucleotide sequences at the ends of chromosomes during cell division. This process is a natural part of cellular aging and is linked to the regulation of the cell cycle, impacting growth control and ultimately influencing cellular lifespan and senescence.

5 Must Know Facts For Your Next Test

1. Every time a somatic cell divides, telomeres shorten, typically by about 50-200 base pairs per division.
2. When telomeres become critically short, they trigger DNA damage responses that can lead to cell cycle arrest or apoptosis.
3. In normal somatic cells, telomerase is usually inactive, leading to progressive telomere shortening, while in stem cells and many cancer cells, telomerase activity helps maintain telomere length.
4. Telomere shortening has been linked to age-related diseases, including cardiovascular disease and various forms of cancer.
5. Research suggests that lifestyle factors such as stress, diet, and exercise can influence the rate of telomere shortening.

Review Questions

• How does telomere shortening affect the cell cycle and what implications does this have for cellular aging?
  • Telomere shortening affects the cell cycle by triggering checkpoints that can halt cell division once telomeres reach a critical length. This leads to cell senescence or apoptosis, which plays a significant role in cellular aging. As cells accumulate damage over time and their telomeres shorten, this process contributes to tissue dysfunction and age-related diseases.
• Discuss the role of telomerase in maintaining telomere length and its relevance to both stem cells and cancer.
  • Telomerase plays a vital role in extending telomeres by adding repetitive nucleotide sequences back onto chromosome ends. In stem cells, this allows for continuous division and regeneration of tissues. Conversely, many cancer cells reactivate telomerase, enabling them to bypass normal cellular aging processes and proliferate uncontrollably, contributing to tumor growth.
• Evaluate the potential therapeutic implications of targeting telomere shortening in age-related diseases and cancer treatment.
  • Targeting telomere shortening presents promising therapeutic avenues for age-related diseases and cancer treatment. By enhancing telomerase activity or developing agents that protect against telomere loss, researchers aim to improve cellular health and longevity. However, caution is needed as manipulating telomerase in cancer cells could inadvertently promote tumor growth; therefore, strategies must be refined to balance benefits with risks.

Related terms

Telomeres: Telomeres are protective caps made of repetitive DNA sequences located at the ends of chromosomes, preventing degradation and fusion with neighboring chromosomes.

Cell Senescence: Cell senescence is a state of stable cell cycle arrest that occurs when cells reach a critical level of telomere shortening, contributing to aging and tissue dysfunction.

Telomerase: Telomerase is an enzyme that adds nucleotide sequences to the ends of telomeres, counteracting the shortening process and playing a crucial role in stem cell maintenance and cancer biology.