P53-DEPENDENT INDUCED AND DEPRESSED GENES IN SPACE CULTURED CELLS
Researchers previously published the induction of p53 gene products in the muscles and skin of
a space-flown rat. The p53 gene product is understood to control apoptosis, cell cycle, and DNA
repair as a genome guardian that depresses gene instability and induction of mutation,
chromosome aberration, and carcinogenesis. Scientists prepared 2 kinds of human-cultured cell
lines of lymphoblastoid cells bearing wtp53 and mp53 gene statuses. Researchers found many
new kinds of p53-regulated genes induced by space radiations, by microgravity, and the space
environment, though the induction of p53 gene product itself was never understood. In
addition, space radiations synergistically induced 209 genes by microgravity, while 166
synergistic depression genes altered by microgravity.
P53-DEPENDENT INDUCED AND DEPRESSED PROTEINS IN CULTURED CELLS IN SPACE
Scientists also analyzed p53-dependent protein synthesis using protein chips of the space
cultured cells. These reports were the first findings in the world.
P53-DEPENDENT INDUCED AND DEPRESSED GENES THAT WERE EXPOSED TO SPACE RADIATIONS
The flight samples were exposed to space radiations for 133 days in space in a frozen state.
After spaceflight, the cells were cultured on the ground. Researchers analyzed the p53-
dependent gene expression in these cells. Induced and depressed genes were 50 and 94,
respectively. Heat shock protein (HSP) genes were also found and were induced by low doses of
radiations (4).
RADIO-ADAPTIVE RESPONSE IN SPACE-FLOWN CELLS IN A FROZEN STATE
The flight samples were exposed to space radiations for 133 days in space in a frozen state.
After spaceflight, the cells were cultured on the ground and then irradiated by X-rays at 2 Gy.
Thereafter, the cells were cultured again for measurements of a radio-adaptive response of cell
survival, apoptosis, and chromosomal aberration. Scientists detected the radio-adaptive
response in wtp53 cells but not in mp53 cells. These results suggested that the flown cells in
space were exposed to space radiations in the range of 20-100 mSv because reports already
revealed that the radio-adaptive response was found in those specific radiation doses.
PUBLICATION(S)
Takahashi A, Suzuki H, Omori K, et al. Expression of p53-regulated proteins in human cultured
lymphoblastoid TSCE5 and WTK1 cell lines during spaceflight. Journal of Radiation Research.
2012;53(2):168-175. doi: 10.1269/jrr.11140.
Takahashi A, Suzuki H, Omori K, et al. Expression of p53-regulated genes in human cultured
lymphoblastoid TSCE5 and WTK1 cell lines after spaceflight in a frozen state. Advances in Space
Research. March 15, 2011;47(6):1062-1070. doi: 10.1016/j.asr.2010.11.002.
Takahashi A, Nagamatsu A, Su X, et al. The first life science experiments in ISS: Reports of “Rad
Gene” - Space radiation effects on human cultured cells. Biological Sciences in Space.
2010;24(1):17-41.