Another "closure" in gerontology
An article published a few months ago in the journal Nature by Chinese researchers Mitoflash frequency in early adulthood predicts lifespan in Caenorhabditis elegans (for a popular summary, see the article "Mitochondrial beacons predict life expectancy") became a minor sensation: it seemed that they managed to find the cause of aging of living organisms. However, an international group of scientists has refuted the basic assumption on which this work was based, and the true cause of aging has again eluded specialists.
The publication of Chinese authors caused a significant resonance in the scientific community. Using a simple measurement method, they were able to predict the life expectancy of young nematode individuals.
Mitochondria are the energy centers of the cell, the normal functioning of which is the key to the flow of all cellular processes. Many experts consider mitochondria to be a kind of biological clock that triggers the aging process. It is believed that this mechanism is based on free radicals – highly reactive molecules that are a byproduct of the breakdown of nutrients for energy. These molecules can damage cellular structures, which eventually reduces the functionality of the cell and leads to its death.
The free radical theory of aging was first proposed almost 40 years ago. However, no convincing evidence has yet been obtained for the existence of a relationship between mitochondrial activity, free radical formation and aging.
It seemed that En-Ji Shen and his colleagues had finally managed to solve this problem. Their proposed approach was to introduce a fluorescent probe cpYFP (circularly permuted Yellow Fluorescent Protein, circularly moving yellow fluorescent protein) into the mitochondria of young nematode cells as a free radical detector. And indeed: the more often the probe emitted a glow, that is, the more free radicals the mitochondria produced, the shorter the lifespan of the worms.
However, as a study by an international team working under the leadership of Dr. Markus Schwarzlander from the University of Bonn showed, the underlying assumption of this work turned out to be incorrect. In fact, the cpYFP probe does not allow us to estimate the amount of free radicals. Instead, the signals it emits indicate a change in the level of acidity (pH) inside the mitochondria.
According to Dr. Schwarzlander, based on the results obtained by Chinese scientists, it is impossible to conclude that the activity of the release of free radicals determines life expectancy, since the cpYFP fluorescent probe is not suitable for these purposes. However, he adds that the demonstrated relationship between the frequency of the probe glow and the lifespan of nematodes is of great interest. Currently, his group is trying to figure out the true causes of this phenomenon.
Article by Markus Schwarzlaender et al. The ‘mitoflash’ probe cpYFP does not respond to superoxide is published in the journal Nature.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of Bonn: Cause of Aging Remains Elusive.
24.10.2014