It is known that our muscles and bones become atrophic under the weightless condition in space, due to the reduction of physical load on the skeletal muscles. Besides, manned Mars exploration and long stay in a space station carry some risks of cataract or DNA damage by space radiation. It is essential for us to overcome these space environment risks when we stay and work in space for a long time, and it is important even in our daily life for bedridden people and patients of adult diseases, such as cancer.

 RNA inference (RNAi) is a phenomenon that messenger RNA (mRNA), which is complementary to the double-stranded RNA, is specifically degraded. RNAi inhibits specific gene expression selectively. This system was discovered by American scientists in 1998, using nematode, which is one of the model organisms. After that, similar systems were found in mammal cells, including human cells. The Nobel Prize in Physiology or Medicine was presented to the two discoverers in 2006. From today, the RNAi method has been developed as one of gene therapies for carcinogenesis and ocular diseases.

 Our research group was inspired by the revolutionary research paper in 1998, and in the same year, we reported that RNAi enables us to analyze functions of the genes related to repair of damaged DNA in nematode. In addition, we participated in International Caenorhabditis elegans Experiment (ICE-First) in 2004, and revealed that spaceflight decreases muscle protein of nematode. Through these researches, we presented “RNA interference and protein phosphorylation in space environment using the nematode Caenorhabditis elegans” to the Fifth International Life Science Solicitation for space experiment in 2005, and it was adopted. However, because of the accident investigation of the space shuttle Columbia, the experiments started in 2009, when Kibo laboratory of the International Space Station was completed. The experimental materials were loaded on the STS-129 Space shuttle Atlantis in November 2009, and the experiments had been conducted in Kibo laboratory within 8 days from November 19, 2011. Samples were frozen in space and returned to Earth by STS-130 the Space shuttle Endeavour in February 2010.

 These samples have been analyzed by Tohoku University, Japan Aerospace Exploration Agency (JAXA), and University of Nottingham. As a result, even under the weightless condition in space, selective RNAi effect has been observed, targeting each of the three different genes (nematode recombinant GFP, protein for cell proliferation, and enzyme degrading α-actin which composes muscles). In the future, the present study is expected to be applied for a measure against muscle atrophy under the weightless condition in space.

 The research result was accepted in the Apil 21 issue of PLos One, and will be published online soon. The paper’s title is “The Effectiveness of RNAi in Caenorhabditis elegans is Maintained During Spaceflight”.

More information (Japanese)  

[Contact]

Professor Atsushi Higashitani

Graduate School of Life Sciences, Tohoku University

Tel: +81-22-217-5715, +81-22-217-5745

E-mail: ahigashi*ige.tohoku.ac.jp (Replace * with @)

Related URL:

http://kibo.jaxa.jp/experiment/theme/first/cerise/

http://kibo.jaxa.jp/experiment/theme/first/cerise/report.html