Type I muscle atrophy caused by microgravity-induced decrease of myocyte enhancer factor 2C (MEF2C) protein expression

To investigate the molecular mechanisms of muscle atrophy under microgravit y, the paraspinal muscles of rats after 14 days spaceflight and those of gr ound-based controls were examined. In the microgravitational environment, e xpressions of 42 genes changed, and the expressions of heat shock protein 7 0 and t complex polypeptide 1 increased. In Northern blotting, myocyte-spec ific enhancer binding factor 2C (MEF2C) and MEF2C-related genes including a ldolase A and muscle ankyrin decreased. After 9 days ground recovery, expre ssion of MEF2C increased and it was located mainly on the satellite cells i n the muscle regeneration state. MEP2C could be a key transcriptional facto r for skeletal muscle atrophy and regeneration under microgravity, (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Scienc e B.V.d All rights reserved.