Date of Award

2018

Document Type

Open Access Thesis

Department

Exercise Science

Sub-Department

The Norman J. Arnold School of Public Health

First Advisor

Mark Sarzynski

Abstract

PURPOSE: MicroRNAs (miRNAs) are small regulatory RNAs that post transcriptionally modify mRNAs and control gene expression. Circulating miRNAs are significantly altered following a single session of exercise, however the effects of exercise training on the circulating miRNA profile is unclear. Therefore, the purpose of the present study was to determine the effects of endurance exercise training on the abundance of targeted circulating miRNAs and the association of changes in miRNA levels with concomitant changes in cardiometabolic traits, in a subsample of adults from the HERITAGE Family Study.

METHODS: This exploratory analysis examined 20 previously sedentary adults from the HERITAGE Family Study who completed 20 weeks of endurance exercise training. miRNAs were isolated from serum samples taken at baseline and post-training. The expression of 84 miRNAs related to cardiovascular disease and development was measured at both time points by performing RT-qPCR on the Human Cardiovascular Disease miScript miRNA PCR array (Qiagen, Hilden, Germany). Fold change was calculated as 2-ΔΔCt using the global geometric mean signal of all detected microRNAs as the normalizer value. Paired t-tests were used to examine the effects of exercise training on individual miRNA levels.

RESULTS: Exercise training resulted in nominally significant down-regulation of five miRNAs (miR-155-5p, let-7b-5p, let-7e-5p, miR-486-5p, and miR-7-5p) compared to baseline (Fold change: 0.33-0.76, p=0.01-0.04). Change in miR-486-5p expression was iii moderately correlated with change in small high-density lipoprotein particle concentration (r = -0.55, p=0.01) and change in low-density lipoprotein particle size (r=0.53, p=0.01). Additionally, change in miR-7-5p was correlated with change in very low-density lipoprotein particle concentrations (r = -0.47, p=0.04).

CONCLUSIONS: Exercise training altered the expression of specific miRNAs associated with cardiovascular disease, which was related to concomitant changes in the plasma lipoprotein profile. MiRNAs therefore represent a potential mechanism that partially mediates the beneficial effects of exercise on cardiometabolic traits. Further research is needed to understand the complete effects of exercise on the circulating miRNA profile.

Rights

© 2018, Jacob Luther Barber

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