Submitted on February 28, 2008
Accepted on April 19, 2008
An in vivo and in vitro assessment of TOR signalling cascade in rainbow trout (Oncorhynchus mykiss)
Iban Seiliez1*, Jean-Charles Gabillard2, Sandrine Skiba-Cassy3, Daniel Garcia-Serrana4, Joaquim Gutierrez5, Sadasivam Kaushik1, Stephane Panserat6, and Sophie Tesseraud7
1 UMR1067 Nutrition Aquaculture et Genomique, INRA, Saint-Pee-sur-Nivelle, F-64310 , France
2 Croissance et qualite de la chair, Institut National de la Recherche Agronomique, Rennes, France
3 NuAGe, INRA, Saint Pee sur Nivelle, France
4 Departament de Fisiologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, E-08071, Spain
5 Fisiologia, Universitat de Barcelona, Barcelona, Barcelona, Spain
6 Lab Fish Nutr Aquaculture & Genom, INRA-IFREMER, St Pee Sur Nivelle, France
7 UR83 Recherches Avicoles, INRA, Nouzilly, France
* To whom correspondence should be addressed. E-mail: seiliez{at}st-pee.inra.fr.
In mammals, feeding promotes protein accretion in skeletal muscle through a stimulation of the insulin- and amino acid- sensitive mammalian target of rapamycin (mTOR) signaling pathway, leading to induction of mRNA translation. The purpose of the present study was to characterize both in vivo and in vitro the activation of several major kinases involved in the mTOR pathway in the muscle of the carnivorous rainbow trout. Our results showed that meal feeding enhanced the phosphorylation of the Target Of Rapamycin (TOR), the Protein kinase B (PKB), p70 S6 kinase (S6K1) and eIF4E-binding protein-1 (4EBP1), suggesting that the mechanisms involved in the regulation of mRNA translation are well conserved between lower and higher vertebrates. Our in vitro studies on primary culture of trout muscle cells indicate that insulin and amino acids regulate TOR signaling and thus may be involved in meal feeding effect in this species as in mammals. In conclusion, we report here for the first time in a fish species, the existence and the nutritional regulation of several major kinases involved in the TOR pathway, opening a new area of research on the molecular bases of amino acid utilization in teleosts.
