Telomeres are regions of repetitive DNA located at each end of a chromatid and function to prevent chromosomal deterioration
During DNA replication, the extreme ends of the telomere cannot be copied and so the telomere gets marginally shorter
- This occurs because the terminal RNA primer on the lagging strand cannot be replaced (no 3’-attachment point for DNA pol I)
The progressive shortening of telomeres is associated with ageing (senescence), age-related diseases and mortalilty
- Cells have a limited capacity for cellular division (Hayflick limit = ~ 40 – 60 divisions for a typical human cell)
- Telomeric shortening is suggested to be a reason for this limit, as cells may stop dividing when too much telomere DNA is lost
Telomeres can be lengthened by the enzyme telomerase, allowing for continued cell division past the Hayflick limit
- Permanent activation of telomerase can cause cells to become immortal and leads to cancer (uncontrolled cell division)
- Many cancer researchers are currently investigating the viability of telomerase inhibitor drugs as a treatment for cancers
Telomere Shortening
