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First published online August 3, 2006
Journal of Experimental Biology 209, 3209-3218 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02365
Decreased expression of myogenic transcription factors and myosin heavy chains in Caenorhabditis elegans muscles developed during spaceflight

1 Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba, Ibaraki
305-8505, Japan
2 Ames Research Center, National Aeronautics and Space Administration, M/S
239-11, Moffett Field, CA 94035-1000, USA
3 Advanced Engineering Services Co. Ltd., Tsukuba Mitsui Building, 1-6-1,
Takezono, Tsukuba, Ibaraki 305-0032, Japan
4 Graduate School of Life Sciences, Tohoku University, Sendai 980-8577,
Japan
* Author for correspondence (e-mail: higashibata.akira{at}jaxa.jp)
Accepted 5 June 2006
The molecular mechanisms underlying muscle atrophy during spaceflight are not well understood. We have analyzed the effects of a 10-day spaceflight on Caenorhabditis elegans muscle development. DNA microarray, real-time quantitative PCR, and quantitative western blot analyses revealed that the amount of MHC in both body-wall and pharyngeal muscle decrease in response to spaceflight. Decreased transcription of the body-wall myogenic transcription factor HLH-1 (CeMyoD) and of the three pharyngeal myogenic transcription factors, PEB-1, CEH-22 and PHA-4 were also observed. Upon return to Earth animals displayed reduced rates of movement, indicating a functional defect. These results demonstrate that C. elegans muscle development is altered in response to spaceflight. This altered development occurs at the level of gene transcription and was observed in the presence of innervation, not simply in isolated cells. This important finding coupled with past observations of decreased levels of the same myogenic transcription factions in vertebrates after spaceflight raises the possibility that altered muscle development is a contributing factor to spaceflight-induced muscle atrophy in vertebrates.
Key words: spaceflight, muscle remodeling, Caenorhabditis elegans, myosin heavy chain, development