Tampere study finds secret to ageing in cells
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An international team of researchers says that it has found incontrovertible evidence that the ageing process is connected with the DNA of the mitochondria of cells, and its mutations.
Mitochondria are cell organelles which perform a number of key tasks, including energy production.
Results of a working group headed by Howy Jacobs, Professor of molecular biology at the University of Tampere, are contained in an article in the British science magazine Nature, which appeared on Thursday.
The DNA of mitochondria is separate from that of a cell’s nucleus, which contains the genetic code of the organism itself.
Mitochondrial DNA contains instructions for cell respiration, which is perhaps the body’s most important mechanism for turning nutrition into energy for the use of the body.
Jacobs compares the cell respiration mechanism with the engine of a car; a well-tuned engine consumes a minimum amount of fuel, operates efficiently, and produces little exhaust.
Biologists have long suspected that a mitochondrial engine in poor condition produces toxic by-products which damage the cell. The faulty function can be attributed to mistakes in the instructions - the mitochondrial DNA.
The working group developed a strain of mice, whose mitochondria have five to ten times as many mutations as those in the cells of normal mice.
The mice in the experiment would age prematurely: they lost weight, their muscles atrophied, their fat tissue decreased, their spines curved, their fur fell out, and the heart muscles and nervous systems deteriorated.
The experimental mice died at the age of about 11 months, compared with normal mice, which would live for about three years.
The experimental mice were bred at the Karoliniska Institute in Stockholm. The Tampere group analysed the DNA mutations.
The number of mutations in mitochondrial DNA appears to be directly proportional to the emergence of oxygen radicals - the harmful by-products of the mitochondrial engine.
The amount of oxygen radicals would appear to determine the rate at which a body loses living cells, and presumably also stem cells, which are vital for the regeneration and viability of the body.
When the body runs out of stem cells, it undergoes the final processes of ageing, and dies.
Professor Jacobs says that he always doubted the theory, but now the experiments have demonstrated it to be right.
Jacobs says that the mutations in mitochondrial DNA are caused by factors such as chemicals and radiation.
He adds that even though the biological basis of the ageing process can now be understood, it could take some time before the ageing process can actually be slowed down.
Helsingin Sanomat
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| 27.5.2004 - TODAY |
 Tampere study finds secret to ageing in cells |
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