TOKYO - Researchers around the world are turning their attention to mitochondria, the energy-producing structures inside cells, as new discoveries suggest they may hold important clues to slowing aging, preventing disease and extending healthy life.
Mitochondria are widely known from biology classes as the parts of cells that generate energy. Often described as the power plants of life, they use nutrients from food and oxygen from breathing to produce adenosine triphosphate, or ATP, a chemical that functions like a tiny battery for the body. The energy released when ATP breaks down supports virtually every activity needed to sustain life.
Shigeru Yanagi, a professor in the Department of Life Science at Gakushuin University’s Faculty of Science, has been studying mitochondria and their role in aging. Yanagi says mitochondria are both old and new as a subject of research: long known to science, but now attracting fresh global attention as researchers uncover functions that challenge conventional understanding.
One of mitochondria’s most important roles is energy production. Yanagi explained that the human body produces and uses an amount of ATP roughly equivalent to its own body weight each day. A person weighing 78 kilograms, for example, would generate and consume about 78 kilograms of ATP in a day through continuous metabolism.
Mitochondria are found in nearly all cells, ranging from several hundred in some cells to several thousand in others. They are especially abundant in organs and tissues that require large amounts of energy, including the heart, brain and skeletal muscles. Yanagi said about one-third of the cells in heart muscle consists of mitochondria, while mitochondria account for about 10% of total body weight. In a person weighing 78 kilograms, that would amount to about 7.8 kilograms of mitochondria.
Because the heart and brain depend heavily on mitochondrial energy production, damage to mitochondria is most likely to produce serious effects in those areas, as well as in skeletal muscles. When energy supply declines, symptoms and disease can emerge.
Although school textbooks often depict mitochondria as a few green bean-shaped structures inside cells, Yanagi said that image is misleading. In reality, mitochondria exist in far greater numbers and are not naturally green. They appear brownish because they contain iron, which is involved in the flow of electrons used to generate energy.
Images captured by Yanagi’s research group show cells filled with mitochondria. In nerve cells, mitochondria can be seen moving through the cell as long, thread-like structures. Yanagi said mitochondria often become elongated when they are actively producing energy, while they may break into smaller fragments when less energy production is needed. Thread-like connections can improve the efficiency of energy generation, making elongated mitochondria a sign of healthy activity.
Recent research has also revealed that mitochondria may move between cells, a finding that overturns earlier assumptions. Yanagi said mitochondria have been observed appearing to push through the cell membrane and move from one cell to another. He said the phenomenon was first identified in the brain, where glial cells may transfer healthy mitochondria to damaged nerve cells in an apparent effort to help them recover.
Unlike most cellular organelles, which normally remain inside their own cells, mitochondria appear capable of moving between cells and supporting them. This suggests that cells may help one another through the exchange of mitochondria.
Mitochondria also play a key role in cell death. Yanagi said they can trigger programmed cell death, a necessary process that allows the body to remove cells that are no longer needed or have become damaged. This process is essential for normal cell turnover and tissue maintenance.
At the same time, deterioration of mitochondria can accelerate aging. When mitochondria decline in function, they can produce more reactive oxygen species, damaging cells and contributing to age-related changes. Yanagi said if mitochondria deteriorate too early, people may develop various diseases in their 50s or 60s, but if mitochondrial function can be properly controlled, it may become possible to live healthily to 100.
Yanagi has discovered an enzyme called MITOL, which helps maintain normal mitochondrial function. By activating MITOL, his research has indicated the possibility of slowing or preventing aging-related conditions, including disease and skin deterioration.
Yanagi has also identified a substance called mitorubrin, which activates MITOL. In some cells, mitorubrin increased energy production by about threefold. Experiments in mice showed effects including improved motor ability and better cognitive function. These findings suggest that drug development targeting mitochondrial function could one day help prevent a range of diseases linked to aging.
Research into mitochondria may also have implications for cancer treatment. Yanagi said some cancer cells do not depend heavily on mitochondria, and this weakness could be used against them. By forcing mitochondria to operate in a certain way, it may be possible to trigger mechanisms inside the cell that help kill cancer cells.
The potential applications of mitochondrial research extend beyond medicine. Yanagi said the findings could eventually be applied to livestock and agriculture, raising the possibility of wider use in health, food production and longevity science.
Mitochondria have also played a central role in the evolution of life. As scientists continue to uncover their functions, the structures found inside every person’s cells are emerging as a possible key to a new future of healthy longevity.
Source: テレ東BIZ
