Hormonal Status As Determinant Of Serum Exosomal MicroRNA Content In Pre- And Postmenopausal Women

Abstract

PURPOSE:This study investigates the effect of systemic sex steroid status on microRNA content of circulating exosomes (exomiRs) among adult women who differ in menopausal status and use of hormone replacement therapy. Exosomes are small vesicles secreted from various cell types. They function in the intercellular communication as carriers for genetic material, such as mRNAs and microRNAs. We have previously shown that there are specific freely circulating microRNAs which are sensitive for systemic sex steroid status. Therefore, we hypothesized that also the systemic exomiR content might vary according to the circulating estrogen levels. METHODS:We analysed the exomiR content from serum samples of premenopausal women (n=8, 30-40 yrs) and from genetically identical postmenopausal female twin pairs (n=10 pairs, 54-62 yrs) discordant for the use of estrogen based hormone replacement therapy (HRT). Serum exosomes were extracted with precipitation solution followed by RNA extraction by Trisure reagent. Library preparation was performed by TruSeq Small RNA sample preparation protocol (Illumina) and microRNAs were sequenced by MiSeq Desktop Sequencer (Illumina). Data analysis was performed using a customized work-flow including miRDeep2 for microRNA identification and the edgeR R-package for identification of differentially expressed (DE) exomiRs. RESULTS:In total, 241 different exomiRs were detected on the basis of sequencing. The most commonly expressed exomiRs included mir-486-5p, -92a-3p, -16-5p, -451a and -22-3p. In the DE analysis 11 miRs were up- and 20 miRs downregulated significantly in HRT non-users when comparing them to premenopausal women (nominal p