Posts Tagged ‘telomeres’
Who wants to live forever? Some flatworms do, even if it means no sex.
British scientists have found that a species of flatworm can overcome the process of ageing to become potentially immortal and say their work sheds light on possibilities of alleviating ageing and age-related characteristics in human cells.
…The researchers found that the flatworms, known as planarian worms, can continuously maintain the length of a crucial part of their DNA, known as telomeres, during regeneration.
“Our data satisfy one of the predictions about what it would take for an animal to be potentially immortal,” said Aziz Aboobaker, who led the research at Britain’s University of Nottingham. “The next goals for us are to understand the mechanisms in more detail and to understand more about how you evolve an immortal animal…”
Aboobaker’s team studied two types of planarian – those that reproduce sexually, like humans, and those that reproduce asexually by simply dividing in two.
Both types appear to regenerate indefinitely by growing new muscles, skin, guts and even entire brains again and again, Aboobaker explained in a statement about the work, but the asexual ones also renew their stocks of a key enzyme which may mean they can be immortal.
Scientists know that one of the key factors associated with ageing cells is telomere length. Telomeres are sections of DNA that cap the ends of chromosomes, protecting them from damage and the loss of cell functions linked to ageing. Shorter telomeres are thought to be an indicator of faster ageing…
In most sexually reproducing organisms the enzyme is most active during early development, but Aboobaker’s team found that in the asexual worms, the planarian version of the enzyme is dramatically increased during regeneration – a factor that allows stem cells to maintain their telomeres as they divide to replace missing tissues…
Now, if they can just sort out the cause-and-effect relationship. We don’t want immortality gained by no sex. We don’t want no sex resulting from immortality.
By now, most people are probably aware of the therapeutic value of stem cells, as they can become any other type of cell in the human body. One of their main duties, in fact, is to replace those other cells as they degrade.
Once people reach an advanced age, however, even the stem cells themselves start to get old and nonfunctional – when the cells that are supposed to replace the other cells can’t do their job anymore, age-related tissue problems start occurring. A team of researchers from the Buck Institute for Research on Aging in collaboration with the Georgia Institute of Technology, however, may be on the way to solving that problem. They have succeeded in reversing the aging process in human adult stem cells.
When regular cells become aged, the caps on the end of their chromosomes (known as telomeres) get shorter. It is therefore hypothesized that many age-related problems are due to the shortening of these telomeres. Given that adult stem cells retain their full telomeres, however, the scientists had to find some other discernible way in which they age.
To do so, they compared the DNA of freshly-isolated adult stem cells from young donors, with that of stem cells from the same donors, but that had undergone an accelerated aging process in the lab. It turned out that most of the DNA damage in the older cells was due to the activity of parts of the cell genome known as retrotransposons. While young cells are able to limit this activity and deal with the damage it causes, older cells are not.
By suppressing the “accumulation of toxic transcripts” from the retrotransposons, however, the researchers were able to reverse the aging process in the older stem cells. They were, in fact, even able to regress them to an earlier stage of development.
The Buck Institute/Georgia Tech team is now looking at how suitable the rejuvenated stem cells may be for treating degenerative disorders such as arthritis, osteoporosis and metabolic syndromes.