Brussels, 13 Jul 2006
European researchers have identified the protein which they say plays a crucial role in the ageing process and conditions such as Parkinson's disease.
Mitochondria organelles are found in their thousands in any one cell, occupying up to 25 per cent of the cell's cytoplasm. While the primary function of mitochondria is to act as 'cellular power plants,' converting oxygen into energy, they also play a role in initiating apoptosis, a process in which damaged cells that cannot be repaired are destroyed in a controlled manner. Ageing, and the process of deterioration that goes with it, is largely attributable to this programmed cell death.
Given their role in this process, researchers at the Flanders Interuniversity Institute for Biotechnology (VIB) and the Italian Dulbecco-Telethon Institute decided to take a closer look at the functioning of mitochondria, and in particular, one of its proteins: PARL. Previous studies on the protein had provided clues as to its functioning. For example, one study showed how it interacts with the Presenilin gene, which when mutated can cause a form of Alzheimer's disease.
To obtain further insight to PARL's functioning, the Belgian and Italian team observed 'knock-out' mice, mice that were no longer able to produce the protein. They saw that these mice deteriorated very rapidly, losing muscular strength after only four weeks, which greatly reduced their capacity for breathing. After eight to 12 weeks, they died.
Although the mitochondria in the mice functioned normally, converting oxygen into energy, they had apparently lost their protection from apoptosis, and so the cells died more quickly. From this the scientists deduced that PARL plays a crucial role in stalling the death of cells, the lack of which can lead to weakening of (muscle) cells, a phenomenon that also occurs in the normal ageing process.
The study, which was published in the scientific journal 'Cell', is part of APOPIS, an Integrated Project funded under the 'Life sciences for health' section of Sixth Framework Programme (FP6). The project team is investigating abnormal proteins in the pathogenesis of neurodegenerative disorders. The aim is foster better understanding of disease mechanisms and to translate the results into clinically useful products. APOPIS, which runs until December, brings together 39 research groups from 12 countries.