Resistance Exercise Modifies Extracellular Vesicle Mirnas Targeting Gene Pathways Associated With Muscle Protein Metabolism

Extracellular vesicles (EV) function in cell-cell communication by delivering molecular cargo, such as miRNA, to target cells. miRNA are short, non-coding RNAs that regulate gene expression post-transcriptionally. Resistance exercise is known to promote skeletal muscle hypertrophy and alters EV characteristics and gene expression. The role of EV miRNA in altering resistance exercise-related gene expression remains elusive. PURPOSE: This pilot study aimed to examine the effect of resistance exercise on circulating EV miRNA. METHODS: We collected fasted blood from 10 participants (5 men, 5 women; age: 26.9 ± 5.5 y, height: 1.73 ± 0.11 m, body mass: 74.0 ± 11.1 kg, body fat: 25.7 ± 11.6 %) before (PRE) and immediately after (POST) resistance exercise consisting of six sets of 10 repetitions of back squat using 75% 1RM. We isolated EVs from plasma using size exclusion chromatography and extracted total RNA from EVs using commercially available kits. Illumina NextSeq was used to conduct RNA sequencing. To predict target mRNAs and perform functional analyses, we used Ingenuity Pathway Analysis (IPA) Suite on differentially expressed (DE) miRNAs between PRE- vs POST-EVs (total and by sex). Significance was set at p < 0.05 for DE and p ≤ 0.01 for IPA. RESULTS: We observed 19 DE miRNAs in the total sample from PRE to POST (p < 0.05). IPA revealed 144 gene expression pathways targeted by DE miRNAs, including insulin-like growth factor-I (p = 8.5e-7; gene targets = 31), growth hormone (p = 0.001; gene targets = 18), and androgen signaling (p = 0.002; gene targets = 34) pathways. Examination by sex revealed 29 DE miRNAs in men and 8 in women (p < 0.05 for all), with no overlap between sexes. Fifty gene expression pathways were targeted in men and 4 pathways targeted in women (p < 0.01 for all). mTOR signaling was altered in men (p = 0.01; gene targets = 21) but not in women. CONCLUSION: These data demonstrate that an acute bout of resistance exercise alters EV miRNA that target pathways related to muscle protein turnover. Comparison by sex revealed distinct EV miRNA profiles and targeted pathways. Future work should investigate the mechanistic actions of circulating EV miRNAs in response to resistance exercise and whether these response patterns influence sex-specific phenotypic adaptations.Supported by UK MOD Grant WGCC 5.5.6 - Task 0107