Histone modifications and the expression of genes related to epigenetic regulatory mechanisms in european sea bass (Dicentrarchus labrax) fed a diet supplemented with sodium butyrate

Abstract

The short-chain fatty acid butyrate has positive effects on the health of the intestinal tract and peripheral tissues. The mechanisms of action of butyrate are related to its potent regulatory effect on gene expression since butyrate is a histone deacetylase inhibitor. We investigated in sea bass the effects of buty rate used as a feed additive on fish epigenetics as well as its regulatory role on gene expression. Seven target genes related to inflammatory response and reinforcement of the epithelial defense barrier (tnf interleukin 1beta, il-6, il-8, il-10, muc2) and five target genes related to epigenetic modifications (dicer1, ehmt2, pcgf2, hdac11, jarid2a) were analyzed in fish intestine and liver. We also investigated the effect of dietary butyrate on histone acetylation, by performing an immunoblotting analysis on liver core histone extracts. Results of the 8-week-long feeding trial showed no significant differences in weight gain of sea bass that received 0.2% Na-butyrate in the diet in comparison to control fish that received a diet without Na-butyrate. Butyrate led to a threefold increase in the acetylation level of histone H4 at lysine 8, but showed no effect on the histone H3 at Lys9. Moreover, two different isoforms of histone H3 that might correspond to the H3.1 and H3.2 isoforms found in terrestrial animals were separated on the immunoblots. The expression of four out of seven analyzed genes related to mucosal protection and inflammatory response was significantly different between the two analyzed tissues but only il10 showed differences in expression due to the interaction between tissue and butyrate treatment. In addition, butyrate caused significant changes in vivo in the expression of genes related to epigenetic regulatory mechanisms such as hdac11, ehmt2, and dicer1. Statistical analysis by 2-way ANOVA for these genes showed significant differences due to butyrate treatment, and to the interaction between tissue and treatment