Cellular content of p53 protein in rat skin after exposure to the space environment

The effects of stress in space, microgravity and space radiation, on living organisms are still unknown. We have examined the cellular content of p53 protein, a tumor-suppressor gene product, in skin from rats by the Western blot method using a blotting-amplification system. Three groups of rats were used. The first group was kept on Earth normally and showed hardly any detectable p53 protein. The second group made a 14-day flight into space on the second Spacelab Life Sciences-2 mission (F). The last group was subjected to the same kinds of stress as the rats in the second group except for spaceflight (SC). The F and the SC rats were killed on day zero (F-0 and SC-0 groups) and day nine (F-9 and SC-9 groups) after return. F-0 rats showed marked accumulation of p53 protein, whereas SC-0 rats showed a slight decrease. F-9 and SC-9 rats showed almost the same amount of p53 protein, but F-9 rats showed a slightly higher expression. From these results, it is suggested that the accumulation of cellular p53 protein is induced in rat skin cells by exposure to the space environment.