Sirtuins and cellular metabolic stress in two gilthead sea bream strains with different growth performance

Abstract

Sirtuins (SIRTs) are conserved deacetylases that couple metabolism with the energy status of cells. This feature makes them putative tools for marker assisted selection of traits such as energy utilization in fish. The aim of this study was to evaluate sirts as indicators of metabolic capacities by assessing their co-expression with markers of intermediary metabolism and intestine function in two gilthead sea bream strains with known differences in growth performance. The fast growing fish strain (strain 1) exhibited higher feed intake, feed efficiency and plasma IGF-I levels, in combination with higher hepatosomatic and lower mesenteric fat indexes. This may reflect an increased flux of fatty acids (FAs) from adipose tissue to liver. Low sirt1 expression in the liver of strain 1 indicated reduced energy demand and oxidative stress, sustained by low expression of genes related with oxidative metabolism. High influx of FAs from diet and adipose tissue in this fish strain was counteracted by antisteatosic mechanisms such as lower lipogenesis, higher long-chain polyunsaturated FA synthesis, and higher lipid disposal to other tissues. Lower adiposity of strain 1 fish was accompanied by up-regulation of sirt5 and sirt6 in the adipose tissue. The white skeletal muscle of the fast growing fish showed an increased expression of sirt2 and genes involved in FA oxidation, metabolic efficiency, and control of reactive oxygen species. Gene profiling indicated that improved intestinal health and functionality allow fish to sustain high ingestion rates and fast growth. Several sirtuins (sirt2, sirt3, sirt5, sirt7) were up-regulated at the posterior intestine of the fast growing strain, and they may perform antiinflammatory actions. This study identified metabolic features linked with a fast growth and lean phenotype, including a tissue specific SIRTs expression pattern that may assist in the metabolic phenotyping of fish.