[72]

Geranylgeranylaceton increases protein content and heat shock protein 72 expression in skeletal muscle cells.     K. Goto^{1, 2}, S. Morioka², T. Naito², A. Kojima², T. Akema², H. Fujiya³, T. Sugiura⁴, Y. Ohira⁵ and T. Yoshioka^{2, 6}. ¹Lab. of Physiol, Toyohashi SOZO Univ., Toyohashi; Depts. of ²Physiol. and ³Sports Medicine, St. Marianna Univ. Sch. of Med., Kawasaki; ⁴Yamaguchi Univ., Yamaguchi; ⁵Graduate Sch. of Med., Osaka Univ., Toyonaka; ⁶Hirosaki Gakuin Univ., Hirosaki, Japan.

   Heat-stress as well as mechanical stress activate proliferative potential and induce muscle hypertrophy.  Up-regulation of heat shock protein 72 (HSP72) induced by heat stress may be one of the signals for muscle hypertrophy.  HSP72, a stress-inducible HSP70, is one of the best-known endogenous factors protecting cell and tissue injury under pathophysiological conditions.  In skeletal muscles, it has been reported that the preconditioning by heat stress to increase the HSP72 expression could attenuate muscle atrophy induced by unloading.  Antiulcer drug geranylgeranylaceton (GGA) stimulates HSP72 expression in the gastric mucosa, small intestine, and heart in rats.  However, the effects of GGA on protein expressions in skeletal muscle cells are unclear.  The purpose of the present study was to investigate the effects of GGA on HSP72 expression of cultured skeletal muscle cells.  Mouse skeletal muscle cells (C2C12) were plated on collagenized culture dishes.  Contents of HSP72 and total muscular protein were up-regulated by GGA.  Evidences suggest that GGA may be a useful tool for a countermeasure for muscoskeletal deconditioning.

(Supported, in part, by Grant-in-Aid for Scientific Research (C, 17500444, KG), (C, 15500453, TY), and (S, 19100009, YO) from Japan Society for the Promotion of Science, Ground-based Research Program for Space Utilization from Japan Space Forum (KG)).