Analysis of porcine miRNA-33b expression in liver and longissimus dorsi muscle and its role in fatty acid metabolism

Resumen del póster presentado a la 37th International Conference on Animal Genetics (ISAG), celebrada en Lleida (España) del 7 al 12 de julio de 2019.

miRNAs are small RNA molecules that are involved in post-transcriptional gene regulation and play important roles in diverse regulatory pathways of many cellular processes. In humans, the miRNA-33 family, which is composed of miRNA-33a and miRNA-33b, was reported to be co-transcribed with SREBP transcription factors and was involved in the regulation of lipid metabolism genes. miRNA-33b was the only member of the family studied in pigs and it was suggested that regulates fatty acid oxidation in adipose tissue. The aim of this work was to study the expression of porcine miRNA-33b in liver and longissimus dorsi muscle, to better understand its biological role in lipid metabolism. The expression of pig miRNA-33b was analyzed in 41 animals from an Iberian × Landrace cross in liver and muscle. RT-qPCR for miRNA-33b was performed with Taqman MicroRNA Assays, using miRNA-let7a and miRNA-26a as porcine reference miRNAs. TargetScan and miRGate algorithms were used to identify potential miRNA-33b targets. Liver and muscle mRNA expression of 44 lipid metabolism-related genes was analyzed in the same set of animals by Fluidigm Real-Time PCR. miRNA-33b expression levels were higher in muscle (mean = 5.01, SD = 0.64) than in liver (mean = 2.49, SD = 3.26) and a moderate correlation (r = 0.34, p-value = 3.5x10−02) was found between them, suggesting different regulatory mechanisms of miRNA-33b in both tissues. Overall, small correlations were found among the expression of miRNA-33b and lipid-related genes in liver (r = −0.26 to 0.31) and muscle (r = −0.35 to 0.37) tissues. In fact, no correlation was found between SREBPF1 and miRNA-33b. In liver, miR-NA-33b showed a negative correlation with CPT1A gene (r = −0.26, p-value = 9x10−02), which was previously described in human as a target gene for mitochondrial β-oxidation. The obtained results suggest that miRNA-33b is involved in the regulation of the b-oxidation pathway in liver but not in muscle. Further analysis will be performed to study the regulatory role of miRNA-33b in adipose tissue and miRNA-33a in liver, adipose tissue and muscle to better understand the miRNA-33 family role in lipid metabolism.