[Myo Lab]
Cbl-Mediated Protein Ubiquitination Downregulates the Response of Skeletal Muscle Cells to Growth Factors in Space

RESEARCH OVERVIEW

• A gene modified cell line from rat muscle cell (L-6) which can be grown as an attached culture in the MeasExp culture chamber, will be launched at ambient temperature using a “MeasExp CO₂ bag,” which maintains an adequate concentration of CO₂.
• After medium exchange (5 +/- 1 day) using “MeasExp Solution Exchanger” by a crewmember, the cells are cultivated using the Cell Biology Experiment Facility (CBEF) at 37 degrees Celsius for 12 days.
• After 10 days (+/-2 days) of incubation, another medium exchange, including IGF-1 for half of the chambers, incubation should be carried out for one day.
• After a total of 11 days (+/-2 days) of incubation, all chambers are washed by a PBS (Phosphate Buffered Saline) solution, exchanged by RNAlater^TM for preserving RNA, and frozen to recover (in MELFI and STS freezer).
• After recovery, cells are analyzed for microgravity effects using RT-PCR (Reverse Transcription-Polymerase Chain Reaction - the most sensitive technique for mRNA detection and quantitation currently available) assay, DNA microaray and western blotting techniques.

DESCRIPTION

The number of bedridden elderly people in Japan is remarkably increasing, which can be considered as a serious social problem. However, there is no effective countermeasure for muscle atrophy (decrease in muscle mass), which is a main cause for bedridden conditions. The few countermeasures for unloading mediated muscle atrophy include: rehabilitation, diet and drugs. The MyoLab payload will focus on the inhibition of Cbl-b-mediated ubiquitination (enzyme found in humans) to improve IGF-1 (insulin-like growth hormone) resistance of skeletal muscle cells. Ubiquitin ligase Cbl-b is inhibited by focusing on the competitively inhibitory function of oligopeptides (molecules containing a small number of peptides).

NIKAWA Takeshi [University of Tokushima]