An antioxidative stress regulator protects muscle tissue in space, mouse
study shows
Researchers find that a master regulator of the oxidative stress response affects muscle composition during space flight

Date:
July 8, 2021
Source:
University of Tsukuba
Summary:
Researchers have found that nuclear factor E2-related factor 2, a
master regulator of the oxidative stress response, affects muscle
composition in microgravity. Targeting this protein could help
protect against muscle changes during space flight, and could also
have implications for muscle wasting in conditions such as cancer
and aging.



FULL STORY ==========================================================================
Most kids dream of growing up to be astronauts; but the downside of
spending extended amounts of time in low gravity is that astronauts'
muscles tend to shrink and weaken through disuse. Now, researchers from
Japan have identified a protein that affects how muscles respond to
space flight.


==========================================================================
In a study published in June 2021 in Communications Biology, researchers
from the University of Tsukuba have revealed that nuclear factor
E2-related factor 2, or NRF2, helps keep muscles from becoming weak in
low gravity.

Muscle atrophy, or weakening, is a common feature of disease and aging. It
can also occur after a long period of inactivity, such as during space
flight, when astronauts don't need to use their muscles as much as they do
on Earth to support their weight or move around. When muscles atrophy in
space, they not only decrease in size, but they also tend to lose a type
of fiber called "slow- twitch" and gain more fibers called "fast-twitch."
"This conversion from slow- to fast-twitch muscle fibers is closely
associated with an increase in oxidative stress," explains Professor
Satoru Takahashi, the senior author of the study. "Thus, we expected that removing factors that protect against oxidative stress would accelerate
muscle atrophy under microgravity conditions." To explore this, the researchers deleted the gene encoding NRF2, which helps controls the
body's response to oxidative stress, in mice. The mice were then sent
to live on the International Space Station for a month. When the mice
returned, the researchers compared their calf muscles with those from
mice who had spent the same month on Earth.

"We were surprised to find that the Nrf2-knockout mice did not lose any
more muscle mass than the control mice under a microgravity environment,"
says Professor Takahashi. "However, they did show a significantly
accelerated rate of slow-to-fast fiber type transition." In addition
to this change in muscle composition, there were also noticeable changes
in the way that the muscle tissue used energy and nutrients. This shift
in energy metabolism is a common feature of fiber type transition.

"Our findings suggest that NFR2 alters skeletal muscle composition
during space flight by regulating oxidative and metabolic responses,"
states Professor Takahashi.

Given this newly discovered role for NFR2, finding treatments that
target this protein could be useful for helping prevent muscle changes in astronauts during space flight. Targeting NFR2 could also be a promising
avenue for addressing muscle wasting in diseases like cancer or during
the aging process.

The article, "Nuclear factor E2-related factor 2 (NRF2) deficiency
accelerates fast fibre type transition in soleus muscle during space
flight," was published in Communications Biology.

This work was supported by a Grant-in-Aid for the Japan Aerospace
Exploration Agency (14YPTK-005512; S.T.), and a Grant-in-Aid for
Scientific Research on Innovative Areas from MEXT (18H04965; S.T.). The
authors declare no competing interests.

========================================================================== Story Source: Materials provided by University_of_Tsukuba. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Takuto Hayashi, Takashi Kudo, Ryo Fujita, Shin-ichiro Fujita, Hirona
Tsubouchi, Sayaka Fuseya, Riku Suzuki, Michito Hamada, Risa Okada,
Masafumi Muratani, Dai Shiba, Takafumi Suzuki, Eiji Warabi, Masayuki
Yamamoto, Satoru Takahashi. Nuclear factor E2-related factor 2
(NRF2) deficiency accelerates fast fibre type transition in soleus
muscle during space flight. Communications Biology, 2021; 4 (1)
DOI: 10.1038/s42003- 021-02334-4 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210708111457.htm

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