[Ribosome Profiling]
Genome-wide survey of translational control in microgravity

RESEARCH OVERVIEW

• Although the control of protein synthesis has been recognized as a pivotal layer of gene regulation, translational regulation occurring in the microgravity environment has not been studied.
• In the Genome-wide Survey of Translational Control in Microgravity (Ribosome Profiling) investigation, the “ribosome profiling” technique is used to evaluate translational changes under the microgravity in a genome-wide manner. A comprehensive survey of the data will focus on the genes regulated in space, particularly at the translation level.
• Because spaceflight often causes aging-related changes, such as muscle loss in astronauts, the results of this study contribute to why such phenomena occur, and to provide a better understanding on how to diagnose and treat.

DESCRIPTION

Living organisms on the Earth have evolved in a form suitable for gravity. Although the important role of gravity in gene expression has been suggested, the molecular details how mammalian cells utilize gravity remain unclear. In the Genome-wide Survey of Translational Control in Microgravity (Ribosome Profiling) investigation, the main focus is to understand whether, and how, the microgravity environment of space affects translational regulation in mammalian cells. To this end, changes are monitored comprehensively by genome-wide ribosome profiling. HEK293 cells are cultured aboard the International Space Station (ISS), chemically fixed, and returned to a laboratory on Earth to prepare the library of ribosome profiling. This work is expected to reveal a unique layer of mechanism for gene expression regulation controlled the mechanical property of gravity.

SPACE APPLICATIONS

This investigation provides a comprehensive view of protein synthesis, and insight into its regulation in space. Moreover, the data available by this work provides an important resource for the study of trans-omics in microgravity.

EARTH APPLICATIONS

Investigating gene changes in space may help identify specific genes that contribute to aging. This could contribute to understanding why aging occurs, how to diagnose it, and help develop treatments to slow aging.

OPERATIONAL REQUIREMENTS AND PROTOCOLS

Mammalian cells (HEK293) in enclosed cell culture chambers (Disposable Cultivation Chamber: DCC) are launched under frozen conditions (-95°C) and stored frozen in the Minus Eighty Laboratory Freezer for ISS (MELFI) until the start of the investigation. Cells are thawed, and the liquid inside DCCs is replaced with cell culture medium using JAXA’s Pre Fixation Kit (PFK). After the incubation for 24 hours under 1G conditions in the JAXA Cell Biology Experiment Facility (CBEF), the DCCs are maintained at 37°C under microG or 1G conditions in the CBEF for 24 or 48 hours. Thereafter, the cell culture medium is replaced with the fixation solution for recovery on Earth. The fixed samples need to be stored at -95°C in MELFI until undocking of the SpaceX Dragon Cargo Vehicle. For return, the fixed samples are recovered in frozen (-95°C) conditions.