title: The effectiveness of RNAi in Caenorhabditis elegans is maintained during spaceflight.
abstract: BACKGROUND
  Overcoming spaceflight-induced (patho)physiologic adaptations is a major challenge preventing long-term deep space exploration. RNA interference (RNAi) has emerged as a promising therapeutic for combating diseases on Earth; however the efficacy of RNAi in space is currently unknown.
  
  
  METHODS
  Caenorhabditis elegans were prepared in liquid media on Earth using standard techniques and treated acutely with RNAi or a vector control upon arrival in Low Earth Orbit. After culturing during 4 and 8 d spaceflight, experiments were stopped by freezing at -80°C until analysis by mRNA and microRNA array chips, microscopy and Western blot on return to Earth. Ground controls (GC) on Earth were simultaneously grown under identical conditions.
  
  
  RESULTS
  After 8 d spaceflight, mRNA expression levels of components of the RNAi machinery were not different from that in GC (e.g., Dicer, Argonaute, Piwi; P>0.05). The expression of 228 microRNAs, of the 232 analysed, were also unaffected during 4 and 8 d spaceflight (P>0.05). In spaceflight, RNAi against green fluorescent protein (gfp) reduced chromosomal gfp expression in gonad tissue, which was not different from GC. RNAi against rbx-1 also induced abnormal chromosome segregation in the gonad during spaceflight as on Earth. Finally, culture in RNAi against lysosomal cathepsins prevented degradation of the muscle-specific α-actin protein in both spaceflight and GC conditions.
  
  
  CONCLUSIONS
  Treatment with RNAi works as effectively in the space environment as on Earth within multiple tissues, suggesting RNAi may provide an effective tool for combating spaceflight-induced pathologies aboard future long-duration space missions. Furthermore, this is the first demonstration that RNAi can be utilised to block muscle protein degradation, both on Earth and in space.
authors.affiliation: Division of Clinical Physiology, Royal Derby Hospital, University of Nottingham, Derby, England.
authors.forename: Timothy
authors.initials: T
authors.lastname: Etheridge
authors.forename: Kanako
authors.initials: K
authors.lastname: Nemoto
authors.forename: Toko
authors.initials: T
authors.lastname: Hashizume
authors.forename: Chihiro
authors.initials: C
authors.lastname: Mori
authors.forename: Tomoko
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Hiromi
authors.initials: H
authors.lastname: Suzuki
authors.forename: Keiji
authors.initials: K
authors.lastname: Fukui
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Akira
authors.initials: A
authors.lastname: Higashibata
authors.forename: Nathaniel J
authors.initials: NJ
authors.lastname: Szewczyk
authors.forename: Atsushi
authors.initials: A
authors.lastname: Higashitani
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000201:enzymology / Q000235:genetics* / Q000528:radiation effects; D018534:Earth, Planet; D005786:Gene Expression Regulation / Q000235:genetics / Q000528:radiation effects; D008247:Lysosomes / Q000201:enzymology / Q000528:radiation effects; D035683:MicroRNAs / Q000235:genetics; D009124:Muscle Proteins / Q000378:metabolism; D010447:Peptide Hydrolases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000235:genetics / Q000528:radiation effects; D034622:RNA Interference / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics; D013026:Space Flight; D013997:Time Factors
chemical_list: D035683:MicroRNAs; D009124:Muscle Proteins; D012333:RNA, Messenger; D010447:Peptide Hydrolases