Why do astronauts’ bodies waste away in space? Part of the answer could be provided by space travelling worms. An international collaborative research group sent microscopic worms and human cells aboard the International Space Station where exposure to microgravity caused their mitochondria – the “power plants” within each cell – to produce fewer proteins. This change may help explain the accelerated aging observed in animal cells in space. The findings could point to new ways to slow aging, both during long space missions and here on Earth.
Key messages:
- Microgravity reduces mitochondrial protein production. In human cells and C. elegans worms aboard the International Space Station, mitochondria made significantly fewer proteins under microgravity, slowing a process called mitochondrial translation.
- Mitochondria use gravity as an activation signal. Researchers discovered that mitochondria rely on gravity to trigger their protein-synthesis machinery – a previously unknown biological mechanism.
- The effect is driven by disrupted cell adhesion. Microgravity weakens cells' ability to stick together via surface proteins, and this loss signals mitochondria to reduce protein output.
- The same pathway responds to mechanical stress on Earth, not just in space. Using mouse models, researchers found that exercise and other mechanical stress activates the identical gravity-sensing pathway, increasing mitochondrial protein synthesis.
- The findings could explain astronaut bone and muscle loss and inform aging research. This gravity– mitochondria link may help explain why astronauts lose bone and muscle mass in space, while also offering insight into aging, muscle atrophy, and stress-related diseases on Earth.
Microgravity can change every cell in the body
Life on earth has evolved to grow under the constant pull of gravity. Weakening this force can have detrimental and long-lasting effects. Microgravity, a condition where gravity is extremely weak and objects become almost weightless, can cause a range of health problems in astronauts, including bone loss, muscle weakness, face puffiness, and heart changes. Even after they return to Earth, astronauts’ bodies don’t fully return to normal. Studying how cells, organs and tissues respond to microgravity has helped scientists better understand – and address – these harmful changes to the body.
Since the 1950s, when the first dog was launched into orbit, biological and medical researchers have explored the unique ways life responds to space. Radiation and microgravity can both affect cells during spaceflight. They can trigger oxidative stress – a kind of cellular wear and tear – and cause mitochondria to stop working properly. They can also alter which genes are switched on or off. Over time, these changes can add up to serious, long-term effects on organisms sent to space.
Because spaceflight experiments are difficult and expensive to run, scientists still don't have the full picture of how cells respond to microgravity. Researchers have long suspected that gravity plays a key role in controlling gene activity, but the molecular details remained unclear.
Space-station study uncovers the mitochondrial mechanism
When researchers sent human cells and C. elegans nematode worms to the International Space Station's Japanese Experiment Module, known as "Kibo", they discovered that mitochondria actually use gravity as a cue to ramp up protein production. In microgravity, mitochondria in both human cells and worms made far fewer proteins. Mitochondrial translation – the process by which proteins are formed – slowed down dramatically.
The effect seems to be caused by a disruption to cell adhesion – cells’ ability to use surface proteins to stick together. Microgravity appears to loosen that grip. Researchers traced how this loss of grip sends a signal that changes mitochondrial activity. In doing so, they uncovered a previously unknown pathway that converts an external, physical force – gravity – into an internal cellular response.
Back down to earth
There's a good reason mitochondria have evolved to sense pressure and gravity: muscles on Earth are constantly under mechanical stress, from simply standing upright to walking and exercising.
Using mouse models, researchers found that the gravity-sensing pathway also controls protein production in mitochondria during mechanical stress, such as exercise. In other words, the body has a built-in system for adjusting energy production based on physical demand: more mechanical stress leads to more mitochondrial protein-building, which in turn boosts the cell’s overall function.
These findings could help explain why astronauts lose bone and muscle mass during time in space. But their relevance goes further: understanding this pathway may also shed light on diseases linked to aging, muscle wasting, and mechanical stress here on Earth – not just for astronauts.
Source : Wakigawa, T., Kimura, Y., Mito, M. et al. Gravitational and mechanical forces shape mitochondrial translation. Nat Commun 17, 5552 (2026). https://doi.org/10.1038/s41467-026-74493-z
Frequently asked questions
Does gravity affect gene expression?
Yes. Researchers found that gravity acts as a signal that influences protein production inside mitochondria, the energy-producing structures within cells. Under microgravity, this signalling brings mitochondria to produce far fewer proteins.
Why do astronauts lose bone and muscle mass in space?
Astronaut bone and muscle loss may be linked to reduced mitochondrial protein production caused by microgravity. Without gravity's normal mechanical pull, mitochondria, the energy-producing structures within cells, make fewer proteins, which can affect how muscle and other tissues maintain themselves over time.
Why were worms sent to the International Space Station?
Among other reasons, researchers sent human cells and C. elegans worms to the ISS's Kibo module and found that mitochondria in both species produced significantly fewer proteins under microgravity.
How does microgravity affect mitochondria?
Microgravity weakens cell adhesion — the ability of cells to stick together using surface proteins. This loss of adhesion sends a signal that reduces mitochondrial protein production, revealing a previously unknown pathway linking physical force to cellular activity.
Does this gravity-sensing pathway matter for life on Earth, not just in space?
Yes. Using mouse models, researchers showed that the same gravity-sensing pathway responds to mechanical stress, such as exercise, on Earth, increasing mitochondrial protein production. This suggests relevance to aging, muscle wasting, and stress-related diseases beyond spaceflight.
Last edited: 15 September 2026 10:56
