Apolipoprotein E determines the hepatic transcriptional profile of dietary maslinic acid in mice

Abstract 

The hypothesis that the maslinic acid (MA) of olive oil (OO) dramatically influences hepatic gene expression was tested in mice. Two OOs only differing in the presence of MA were prepared. Using DNA microarrays, we analyzed hepatic gene expression in apolipoprotein E (apoE)-deficient mice with a C57BL/6J genetic background that were fed with isocaloric, isonitrogenous diets containing either 10% (w/w) OO or 10% MA-enriched OO. As an initial screening of potential candidate genes involved in a differential response, this study further considered only genes with remarkably modified expression (signal log₂ ratio higher than1.5 or lower than −1.5). The nine genes fulfilling these prerequisites were confirmed by quantitative reverse transcriptase polymerase chain reaction and analyzed in C57BL/6J wild-type mice. Only Cyp2b9, Cyp2b13 and Dbp expressions appeared significantly increased, and Marco was significantly decreased in apoE-deficient mice receiving the MA-enriched diet. Dbp was up-regulated to an extent depending on the genetic background of the mice and negatively associated with the expression of Marco, a gene strongly up-regulated by the absence of apoE. These expression changes could be used as markers of the intake of the MA-enriched OO and are influenced by genetic background generated by the absence or the presence of apoE. Overall, these results (a) indicate that MA in virgin OO is highly active in controlling hepatic gene expression and (b) highlight the important interaction between the response to MA and the presence of apoE. They also confirm that virgin OO cannot be simplistically classified as monounsaturated fatty-enriched oil without paying attention to its active minor components.

Abbreviations: ALAT, alanine aminotransferase, ANOVA, analysis of variance, apoE, apolipoprotein E, ASAT, aspartate aminotransferase, BSA, bovine serum albumin, EVOO, extra virgin olive oil, IL-6, interleukin 6, MA, maslinic acid, MA-OO, maslinic acid-enriched olive oil, OO, olive oil, PBS, phosphate-buffered saline, qRT-PCR, quantitative reverse transcriptase polymerase chain reaction, ROS, reactive oxygen species, TG, triglyceride

Keywords: Apolipoprotein E-deficient mice, Olive oil, Maslinic acid