One major concern regarding long-term manned space missions is the effect of accumulative doses of space radiation (the mean daily dose is 0.2 ∼ 1 mSv). Such missions will inevitably expose astronauts to significant doses, and thus are expected to increase the risks of radiation-related carcinogenicity, neurotoxicity, and lifespan changes. These effects occur by nuclear and cytosol dysfunction, mitochondrial damage, and particular changes in signal transduction or protein synthesis. In addition, microgravity may affect cellular metabolisms, signal transduction, etc., and might lead to synergistic effects with space radiation, which could result in further risk. Because these effects will almost certainly involve cellular signaling, transcriptomics and proteomics will be powerful tools in their analysis. In order to suitably respond to all these risks, both protective measures based on physical and biological principles, and effective intra-flight assessment of the levels of radiation exposure will be required. In this article, the categories of cell death-i.e., apoptosis, necrosis and autophagy-and the recent studies on these mechanisms are reviewed.
2009 by Japanese Society for Biological Sciences in Space