Temporal Telomere and DNA Damage Responses in the Space Radiation Environment

Telomeres, repetitive terminal features of chromosomes essential for maintaining genome integrity, shorten with cell division, lifestyle factors and stresses, and environmental exposures, and so they provide a robust biomarker of health, aging, and age-related diseases. We assessed telomere length dynamics (changes over time) in three unrelated astronauts before, during, and after 1-year or 6-month missions aboard the International Space Station (ISS). Similar to our results for National Aeronautics and Space Administration’s (NASA’s) One-Year Mission twin astronaut (Garrett-Bakelman et al., 2019), significantly longer telomeres were observed during spaceflight for two 6-month mission astronauts. Furthermore, telomere length shortened rapidly after return to Earth for all three crewmembers and, overall, telomere length tended to be shorter after spaceflight than before spaceflight. Consistent with chronic exposure to the space radiation environment, signatures of persistent DNA damage responses were also detected, including mitochondrial and oxidative stress, inflammation, and telomeric and chromosomal aberrations, which together provide potential mechanistic insight into spaceflight-specific telomere elongation. [Display omitted] •Telomere elongation during spaceflight was observed for two 6-month mission astronauts•Telomere elongation was not dependent on mission duration, sample, or measurement type•Chronic space radiation exposure was associated with persistent DNA damage responses•Telomeres shortened rapidly after return to Earth, and long-term individual differences were observed Consistent with findings first observed for NASA’s One-Year Mission twin astronaut, Luxton et al. report spaceflight-specific telomere elongation in ISS crewmembers on shorter duration missions. Signatures of persistent DNA damage responses in the space radiation environment are also observed, providing potential mechanistic insight into telomere maintenance pathways during spaceflight.