Energy sensing in gilthead sea bream. Molecular and functional characterization of sirtuins

Abstract

Seven nucleotide sequences were unequivocally annotated as sirtuins (SIRTs) 1-7 after extensive searches in the Nutrigroup cDNA database of gilthead sea bream (www.nutrigroup.iat-org/seabreamdb). All isoforms conserved a characteristic enzymatic core domain and phylogenetic analysis showed three major clades according to the accepted classification of SIRTs and the present hierarchy of vertebrate species. Transcriptional studies revealed a ubiquitous SIRT gene expression that was tissuespecific for each SIRT isoform. This was evidenced by multivariate analyses, which established two main clusters corresponding to SIRT isoforms with relatively high (SIRT1, 2 and 5) and low (SIRT3, 4, 6 and 7) expression levels. A nutritional regulation was also evidenced in 10-days fasted fish, and SIRT2, 3 and 4 exhibited an overall down-regulated expression. The opposite trend was reported for SIRT1, 5, 6 and 7, although clustering analyses evidenced a tissue-specific response according to the different tissue metabolic capabilities.