Docosahexaenoic acid modulates the enterocyte Caco-2 cell expression of MicroRNAs involved in lipid metabolism

Authors: GIL-ZAMORANO, JUDIT - MADRID INSTITUTE FOR ADVANCED STUDIES; MARTIN, ROBERTO - MADRID INSTITUTE FOR ADVANCED STUDIES; DAIMIEL, LIDIA - MADRID INSTITUTE FOR ADVANCED STUDIES; RICHARDSON, KRIS - JEAN MAYER HUMAN NUTRITION RESEARCH CENTER ON AGING AT TUFTS UNIVERSITY; GIORDANO, ELENA - MADRID INSTITUTE FOR ADVANCED STUDIES; NICOD, NATHALIE - MADRID INSTITUTE FOR ADVANCED STUDIES; GARCÍA-CARRASCO, BELEN - MADRID INSTITUTE FOR ADVANCED STUDIES; SOARES, SARA M - MADRID INSTITUTE FOR ADVANCED STUDIES; IGLESIAS-GUTIÉRREZ, EDUARDO - UNIVERSITY OF OVIEDO; LASUNCIÓN, MIGUEL - HOSPITAL RAMON Y CAJAL; SALA-VILA, ALEIX - INSTITUTO DE SALUD CARLOS III; ROSE, EMILIO - INSTITUTO DE SALUD CARLOS III; ORDOVAS, JOSE - JEAN MAYER HUMAN NUTRITION RESEARCH CENTER ON AGING AT TUFTS UNIVERSITY; VISIOLI, FRANCISCO - MADRID INSTITUTE FOR ADVANCED STUDIES; DAVALOS, ALBERTO - MADRID INSTITUTE FOR ADVANCED STUDIES

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2014
Publication Date: 5/1/2014
Citation: Gil-Zamorano, J., Martin, R., Daimiel, L., Richardson, K., Giordano, E., Nicod, N., García-Carrasco, B., Soares, S.A., Iglesias-Gutiérrez, E., Lasunción, M.A., Sala-Vila, A., Rose, E., Ordovas, J.M., Visioli, F., Davalos, A. 2014. Docosahexaenoic acid modulates the enterocyte Caco-2 cell expression of MicroRNAs involved in lipid metabolism. Journal of Nutrition. 144(5):575-585. DOI: 10.3945/JN.113.189050.

Interpretive Summary: Consumption of the long-chain omega-3 (n-3) polyunsaturated fatty acid docosahexaenoic acid (DHA) has been associated with a reduced risk of cardiovascular disease (CVD). However, these findings have not been consistent across studies and it is paramount to learn more about the mechanisms underlying the biological effects of DHA. A novel mechanism of gene regulation involves microRNAs (miRNAs). miRNAs are small non-coding RNA molecules (containing about 22 nucleotides) found in plants, animals, and some viruses, which function in transcriptional and post-transcriptional regulation of gene expression. Therefore, we aimed to define whether the beneficial effects of DHA may be modulated in part through this newly discovered regulatory mechanism involving miRNAs. Some of our previous work suggests that lipoprotein (fat) metabolism is regulated in part by these miRNAs. In this work we observed that several miRNA candidates are differentially modulated by fatty acids. Among the miRNAs modulated by DHA were miR-192 and miR-30c. Overexpression of either miR-192 or miR-30c in intestinal and liver cells suggested an effect on the expression of genes related to lipid (fat) metabolism, some of which were confirmed by internal inhibition of these miRNAs. Our results show in cells in the intestine that DHA exerts its biological effect in part by regulating genes involved in lipid metabolism and cancer. Moreover, we validate novel targets of miR-30c and miR-192 related to lipid metabolism and cancer including nuclear receptor corepressor 2, isocitrate dehydrogenase 1, DICER, caveolin 1, ATP-binding cassette subfamily G (white) member 4, retinoic acid receptor beta, and others. Therefore, we have demonstrated that dietary components, such as DHA modulates the expression of specific miRNAs, resulting in subsequent modulation of genes involved in lipid metabolism. Overall, we have identified novel mechanisms of action relating dietary components with gene expression and disease risk.

Technical Abstract: Consumption of the long-chain omega-3 (n-3) polyunsaturated fatty acid docosahexaenoic acid (DHA) is associated with a reduced risk of cardiovascular disease and greater chemoprevention. However, the mechanisms underlying the biologic effects of DHA remain unknown. It is well known that microRNAs (miRNAs) are versatile regulators of gene expression. Therefore, we aimed to determine if the beneficial effects of DHA may be modulated in part through miRNAs. Loss of dicer 1 ribonuclease type III (DICER) in enterocyte Caco-2 cells supplemented with DHA suggested that several lipid metabolism genes are modulated by miRNAs. Analysis of miRNAs predicted to target these genes revealed several miRNA candidates that are differentially modulated by fatty acids. Among the miRNAs modulated by DHA were miR-192 and miR-30c. Overexpression of either miR-192 or miR-30c in enterocyte and hepatocyte cells suggested an effect on the expression of genes related to lipid metabolism, some of which were confirmed by endogenous inhibition of these miRNAs. Our results show in enterocytes that DHA exerts its biologic effect in part by regulating genes involved in lipid metabolism and cancer. Moreover, this response is mediated through miRNA activity. We validate novel targets of miR-30c and miR-192 related to lipid metabolism and cancer including nuclear receptor corepressor 2, isocitrate dehydrogenase 1, DICER, caveolin 1, ATP-binding cassette subfamily G (white) member 4, retinoic acid receptor beta, and others. We also present evidence that in enterocytes DHA modulates the expression of regulatory factor X6 through these miRNAs. Alteration of miRNA levels by dietary components in support of their pharmacologic modulation might be valuable in adjunct therapy for dyslipidemia and other related diseases.