title: Mechanistic target of rapamycin (mTOR) signaling genes in decapod crustaceans: cloning and tissue expression of mTOR, Akt, Rheb, and p70 S6 kinase in the green crab, Carcinus maenas, and blackback land crab, Gecarcinus lateralis.
abstract: Mechanistic target of rapamycin (mTOR) controls global translation of mRNA into protein by phosphorylating p70 S6 kinase (S6K) and eIF4E-binding protein-1. Akt and Rheb, a GTP-binding protein, regulate mTOR protein kinase activity. Molting in crustaceans is regulated by ecdysteroids synthesized by a pair of molting glands, or Y-organs (YOs), located in the cephalothorax. During premolt, the YOs hypertrophy and increase production of ecdysteroids. Rapamycin (1μM) inhibited ecdysteroid secretion in Carcinus maenas and Gecarcinus lateralis YOs in vitro, indicating that ecdysteroidogenesis requires mTOR-dependent protein synthesis. The effects of molting on the expression of four key mTOR signaling genes (mTOR, Akt, Rheb, and S6K) in the YO was investigated. Partial cDNAs encoding green crab (C. maenas) mTOR (4031bp), Akt (855bp), and S6K (918bp) were obtained from expressed sequence tags. Identity/similarity of the deduced amino acid sequence of the C. maenas cDNAs to human orthologs were 72%/81% for Cm-mTOR, 58%/73% for Cm-Akt, and 77%/88% for Cm-S6K. mTOR, Akt, S6K, and elongation factor 2 (EF2) in C. maenas and blackback land crab (G. lateralis) were expressed in all tissues examined. The two species differed in the effects of molting on gene expression in the YO. In G. lateralis, Gl-mTOR, Gl-Akt, and Gl-EF2 mRNA levels were increased during premolt. By contrast, molting had no effect on the expression of Cm-mTOR, Cm-Akt, Cm-S6K, Cm-Rheb, and Cm-EF2. These data suggest that YO activation during premolt involves up regulation of mTOR signaling genes in G. lateralis, but is not required in C. maenas.
authors.affiliation: Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Ali M
authors.initials: AM
authors.lastname: Abuhagr
authors.affiliation: Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Kyle S
authors.initials: KS
authors.lastname: Maclea
authors.affiliation: Bodega Marine Laboratory, University of California-Davis, Bodega Bay, CA 94923, USA.
authors.forename: Ernest S
authors.initials: ES
authors.lastname: Chang
authors.affiliation: Department of Biology, Colorado State University, Fort Collins, CO 80523, USA. Electronic address: Donald.Mykles@ColoState.edu.
authors.forename: Donald L
authors.initials: DL
authors.lastname: Mykles
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003386:Brachyura / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D003001:Cloning, Molecular; D026461:Ecdysteroids / Q000097:blood / Q000378:metabolism; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D008297:Male; D008969:Molecular Sequence Data; D018978:Molting; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D009928:Organ Specificity; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics* / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D046509:Tissue Culture Techniques
chemical_list: D060829:Arthropod Proteins; D026461:Ecdysteroids; D009479:Neuropeptides; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus
keywords: Akt; Crustacea; Ecdysteroid; Molting; Rheb; Target of rapamycin; Y-organ; p70 S6 kinase