P1.56 Wednesday, Jan. 4 Effects of molting on expression of FKBP12, an inhibitor of mTOR-regulated protein synthesis, in crustacean skeletal muscle ROBINSON, AM*; MACLEA, KS; CHANG, ES; MYKLES, DL; Colorado State Univ.; Colorado State Univ.; UC Davis Bodega Marine Lab; Colorado State Univ. email@example.com
During premolt, the claw muscle in crustaceans must atrophy to successfully withdraw the claws from the old exoskeleton. In the blackback land crab, Gecarcinus lateralis, the rate of global protein synthesis in atrophic claw muscles is correlated with hemolymph ecdysteroid titers. This increased protein turnover is associated with extensive remodeling of the contractile structure as muscle fibers are reduced in size. These data suggest that ecdysteroids, either directly or indirectly, stimulate metazoan Target Of Rapamycin (mTOR), a protein kinase complex that promotes translation. We hypothesize that FKBP12 (FK506-binding protein, 12 kDa), an inhibitor of mTOR, is down-regulated in atrophic claw muscle. cDNAs encoding G. lateralis and green shore crab (Carcinus maenas) FKBP12 were cloned. Real-time PCR was used to quantify the effects of eyestalk ablation (ESA) on FKBP12 expression in claw and thoracic muscles of C. maenas (green and red morphs). Both morphs were refractory to ESA, causing only a small increase in hemolymph ecdysteroid level. ESA had a transient effect on FKBP12 expression in green morphs, but not red morphs. There was no correlation of FKBP12 mRNA with hemolymph ecdysteroid titer. We will quantify the effects of molting on FKBP12 expression in G. lateralis muscles. Supported by NSF (IBN-0618203).