Poster abstracts

Poster number 84 submitted by Guido Rossi

Characterization of lipoprotein-bound microRNAs

Guido Rossi-Herring (Bellaterra Campus, Universitat Autnoma de Barcelona, Cerdanyola del Valls, 08041 Barcelona, Spain), David de Gonzalo-Calvo (Institute of Biochemical Research of Barcelona IIBB-Spanish National Research Council CSIC, Barcelona, Spain; Lipids and Cardiovascular Pathology Group, Biomedical Research Institute Sant Pau IIB), Jose Luis Snchez-Quesada (Cardiovascular Biochemistry Group, Research Institute of the Hospital de la Santa Creu i Sant Pau IIB Sant Pau, 08041 Barcelona, Spain)

Abstract:
MicroRNAs (miRNAs) are small non-coding RNAs that control gene expression at posttranscriptional level through targeting of messenger RNA (mRNA) and play an important role in physiological and pathological processes such as cancer, cardiovascular disease and other metabolic diseases. miRNAs have been described in extracellular space and blood transported by extracellular vesicles and proteins. Extracellular miRNAs are also carried by lipoproteins, HDL and LDL; however, technical issues limited their evaluation. Here, we describe the optimal methodology to analyze miRNAs expression in lipoprotein fractions. Additionally, we explored the HDL, LDL and VLDL-miRNA signatures in pure fractions of each lipoprotein. Lipoproteins were isolated from serum by ultracentrifugation and subsequent purification using fast protein liquid chromatography (FPLC). First, the amount of protein needed for RNA isolation in lipoproteins was determined from three serum pools (n=3). 300 μg of protein resulted in the optimal amount of protein for miRNAs expression profiling in lipoproteins. Second, a total of 179 miRNAs were evaluated in the three lipoprotein fractions isolated from serum pools (n=6). A high correlation was observed between VLDL and HDL-miRNA signatures. The LDL-miRNA signature was clustered in a distinctive group. VLDL and HDL shared loaded miRNAs, as well as carried specific miRNAs. Otherwise, LDL did not transport specific miRNAs. Three miRNAs resulted to be highly-expressed in the three lipoproteins (miR-125a-5p, miR-1260a and miR-335-3p). Pathway analysis showed common molecular pathways regulated by the miRNAs expressed in the lipoprotein fractions. Two sequence motifs were detected in HDL-miRNAs, suggesting a possible sorting mechanism for miRNAs. Collectively, these findings support the idea that lipoproteins are carriers of circulating miRNAs. Of note, we show for the first time the miRNA signature of the VLDL fraction. In addition, we describe a new standardization method for miRNA detection in lipoproteins.

References:
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Keywords: miRNAs, lipoprotein, signature