Telomeres and Aging (links)
Many scientists previously thought that aging might arise primarily due to clock-like shortening of telomeres, DNA-protein complexes at the end of each of our chromosomes, with every cell division. This was primarily based upon in vitro experiments wherein the lifespan of cell cultures could be extended past the Hayflick limit (roughly 50 cell divisions) via the addition of telomerase, an enzyme that elongates telomeres. They postulated that telomeres served to prevent cancer cells from dividing indefinitely by cutting off their proliferation at the Hayflick sequence. However, this view appears to be very much overly-simplistic. Telomeres also appear to serve as a sort of "sink" for free radicals, such these molecules as well as other forms of cellular stress can result in shortening of the telomeres, possibly as a signal that damage has occurred. Additionally, if telomeres are regarded as an "aging clock" then neurons should never senesce, because they never divide! So, while research on telomeres and telomerase may prove extremely useful for addressing some forms of cancer and possibly some instances of cellular senesence, this research by no means appears to be any sort of holy grail for the development of life-extension therapies.
Check back soon for more info on telomeres and aging!
Telomere Links (let us know if any are broken!)
- History of telomeres and senescence - 2003, innovita research foundation
- All about telomeres: good page with diagrams - 2003
- All about telomeres - 2001
- All about telomeres: infoaging.org - 2001, American Federation for Aging Research
- Telomere/telomerase basics - University of Texas Southwestern Medical Center at Dallas
- "Turning Back the Strands of Time" - Scientific American article on telomeres, 1998
- GenLink Multimedia Telomere Resource - Washington University, updated 1999, What are telomeres? subpage, and End Relpication subpage
- Outline of telomere topics 2003
- Human fibroblast replicative senescence can occur in the absence of extensive cell division and short telomeres - 2001 (journal subscription required)
- "Implication of telomerase activity and telomere stability for replicative aging and cellular immortality - pubmed article, 1998
- telomeres in mitochondria - research project investigating telomeres in mitochondria
- history of telomeres - The Scientist, 1996
- telomere/telomerase function, transcription factor influence on telomerase, t-loops - lab investigating telomere function and maintenance
- Hayflick, his limit, and cellular ageing
- telomerase inhibition for cancer treatment - Geron page
- targeting telomerase-concentrated cells w/adenovirus - Geron page
- linearization of circular chromosomes in bacterial evolution - pubmed article, 2000
- eukaryotic DNA replication - Oregon State University
- plant genome and longevity: plants lacking telomeres live long w/genomic abuse, not correlated in animals - National Science Foundation, 2001
- p53 somewhat compensates for telomere shortening - pubmed article, 1999
- telomere detection kits - The Scientist, 1998
- evolution of somatic differentiation was the necessary condition for the evolution of senescence. Somatic cells appear to lack mechanisms to prevent the shortening of telomeres; perhaps an evolved trait to limit the proliferative potential of somatic cells in multicellular organisms Research at Pamona, 1997
- "The Paradox of Immortality" - University of Texas Southwestern Medical Center at Dallas, 1996
- "Scientists extend the life span of human cells" University of Texas Southwestern Medical Center at Dallas, 1998