Meeting Abstract
P2.93 Wednesday, Jan. 5 Cloning of FKBP12, an inhibitor of mTOR-regulated protein synthesis, and its expression in crustacean skeletal muscle ROBINSON, A.M.*; MACLEA, K.S.; CHO, I.G.; CHANG, E.S.; MYKLES, D.L.; Colorado State U.; UC Davis Bodega Marine Lab amr0125@gmail.com
During premolt, the claw muscle 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. The purpose of this study was to investigate the cellular mechanisms responsible for this muscle atrophy. We hypothesize that FKBP12 (FK506-binding protein, 12 kDa), a known inhibitor of mTOR, is down regulated in atrophic claw muscle. A cDNA encoding G. lateralis FKBP12 was cloned using RT-PCR and 5’- and 3’-RACE. ESTs encoding FKBP12 from Carcinus maenas and Homarus americanus were sequenced. The deduced amino acid sequences were highly conserved between species. Real-time PCR was used to quantify the effects of eyestalk ablation (ESA) on FKBP12 expression in claw and thoracic muscles of G. lateralis and the green and red color morphs of C. maenas. The two species differed in response to ESA. Both color morphs of C. maenas were refractory to ESA and remained in intermolt. By contrast, G. lateralis entered premolt and proceeded through to ecdysis. ESA had a transient effect on FKBP12 expression in green morph, but not red morph, C. maenas skeletal muscles. FKBP12 mRNA levels increased at 7 days post-ESA and then decreased at 14 days post-ESA in both claw and thoracic muscles. Studies on the effects of ESA and multiple limb autotomy on FKBP12 expression in C. maenas and G. lateraliswill be reported. Supported by an REU supplement to NSF grant IBN-0618203.
