Changes in expression of microRNA potentially targeting key regulators of lipid metabolism in primary gilthead sea bream hepatocytes exposed to phthalates or flame retardants

Metabolism disrupting chemicals (MDCs) belong to the group of endocrine-disrupting chemicals (EDCs) and are known to affect endocrine and metabolic functions of liver. There is growing evidence that MDCs may also act modulating the expression levels of micro ribonucleic acids (miRNAs) and thus affecting post-transcriptional expression of hundreds of target genes. Herein, we used a gilthead sea bream in vitro hepatocyte model for analyzing the effects of an exposure to phthalates (i.e. DiDP) or flame retardants (i.e.TMCP) on the expression levels of three miRNAs (i.e. MiR133, MiR29 and MiR199a) selected on the basis of their regulatory roles in signaling pathways related to lipid metabolism. Following computational identification of genes that are regulated by the selected miRNAs, we identified six miRNA targets to be tested in differential gene expression analysis. To determine whether lipid metabolism was altered we have also measured the intracellular total cholesterol and triglyceride levels. The results of our study show that DiDP/TMCP exposure leads to a general decrease in the expression profiles of each miRNA leading to a corresponding upregulation of almost all their putative targets. In addition, these findings were also associated to a corresponding increased hepatocellular lipid content. The present study thus contributes to support the importance of these small molecules in regulating MDC-induced expression of genes associated with hepatic lipid metabolism and highlights the need for more toxicological studies examining miRNAs transcriptional regulatory networks controlling metabolic alterations in fish.