Nuclear factor E2-related factor 2 (NRF2) deficiency accelerates fast fibre type transition in soleus muscle during space flight

Microgravity induces skeletal muscle atrophy, particularly in the soleus muscle, which is predominantly composed of slow-twitch myofibre (type I) and is sensitive to disuse. Muscle atrophy is commonly known to be associated with increased production of reactive oxygen species. However, the role of NRF2, a master regulator of antioxidative response, in skeletal muscle plasticity during microgravity-induced atrophy, is not known. To investigate the role of NRF2 in skeletal muscle within a microgravity environment, wild-type and Nrf2-knockout (KO) mice were housed in the International Space Station for 31 days. Gene expression and histological analyses demonstrated that, under microgravity conditions, the transition of type I (oxidative) muscle fibres to type IIa (glycolytic) was accelerated in Nrf2-KO mice without affecting skeletal muscle mass. Therefore, our results suggest that NRF2 affects myofibre type transition during space flight. Hayashi et al. report on the effect of space flight on muscle mass, fibre size and type, composition and gene signalling of muscle in WT and Nrf2-KO mice. Their results demonstrate a key role of NRF2 in maintaining the slow-type fibres of soleus muscle during space flight and in microgravity environments.

Automated summary

The study shows that NRF2 plays a key role in maintaining slow-type muscle fibers in the soleus muscle during space flight, impacting the transition of muscle fiber types. These findings provide important insights into the mechanism of skeletal muscle atrophy in microgravity environments.