Exercise Intensity Is A Key Driver Of Differential Smrna Expression In Skeletal Muscle

BACKGROUND: Exercise results in differential small RNA (smRNA/s) expression. smRNAs are a class of non-coding RNAs 15-35 nt in length, generally acting to suppress gene expression. smRNA associated gene silencing may be one of many mechanisms underpinning adaptation to exercise. We evaluated the effects of amount and intensity of aerobic exercise on smRNA expression quantified through smRNA sequencing. Additionally, we sought to identify signaling pathways associated with smRNA expression patterns. METHODS: RNA isolated from PRE and POST skeletal muscle samples (n = 120 [57 female, 63 male]; mean age: 51 ± 8) collected during the STRRIDE trials underwent smRNA sequencing. Resultant FASTQ files were preprocessed using the Qiagen GeneGlobe platform. Raw reads were filtered for low expressors then TMM normalized followed by analysis using a custom-built linear model applying Benjamini-Hochberg adjustment (FDR) to correct for multiple testing. We controlled for baseline smRNA expression, amount and intensity of exercise, age, race, sex, BMIBaseline, and %Δbody weight. RESULTS: Modeling exercise amount, yielded 65 smRNAs predictors (p ≤ 0.05); with intensity in the model, we identified 90 smRNA predictors of amount that were independent of intensity (p ≤ 0.05). Neither model identified smRNAs that passed FDR ≤ 0.05. Intensity yielded 189 smRNAs (p ≤ 0.05); 29 of these smRNAs passed FDR ≤ 0.05. Accounting for amount, we identified 225 smRNA predictors of intensity that were independent of amount (p ≤ 0.05); 28 of these smRNAs passed FDR ≤ 0.05. Differentially expressed (DE) smRNAs were involved in pathways associated with muscle cell regulation and regeneration, metabolism, and inflammation. Interestingly, we identified 57 smRNAs (22.1%) that overlap between the amount and intensity models. CONCLUSIONS: Collectively, these data show that amount but especially intensity of exercise regulate smRNAs in skeletal muscle. Amount and intensity of aerobic exercise resulted in regulation of different smRNAs. DE smRNAs in response to intensity were involved in proteolysis, regeneration, and neural/cognitive function; DE smRNAs in response to amount were involved in pathways related to cell cycle and translational response Supported by NIH Grants R01AG054840 and R01HL153497