Abstract
The space environment contains two main biologically important factors, i.e. space radiations and microgravity. Space radiations are well known to contain heavy particles which induce serious damage in organisms with high relative biological effectiveness as compared with low LET radiations such as X-rays and gamma-rays. The tumor suppressor gene product p53 is generally thought to contribute to the genetic stability of DNA-damaged cells through p53-centered signal transduction pathways. We have already found the accumulation of p53 in the muscle and skin of rats after spaceflight. For the next stage, in the present study we propose to investigate the gene expression of p53-regulated genes in mammalian cultured cells after exposure to space environment. Cells carrying wild-type p53, human lymphoblastoid cells TK6 and cells carrying mutant p53, human lymphoblastoid cells WTK1 (a sub-clone of TK6) are frozen until launching. The cells are molten and then cultured under 0 or 1 g at 37oC during 5 days in International Space Station. After re-freezing, the cells return on the Earth. The data obtained with flight samples will be compared with those of ground control samples. Finally, the experimental results from flight samples might clarify the role of p53-regulated or unknown genes in the genetic instability induced by space stressors. We expect that the data from this proposal will be useful for providing physiological protection against the serious effects of space radiation during long stays in space.
