DNA methylation and proteomics integration uncover dose-dependent group and individual responses to exercise in human skeletal muscle

ObjectiveExercise is a major regulator of muscle metabolism, and health benefits acquired by exercise are a result of molecular shifts occurring across multiple OMIC levels (i.e. epigenome, transcriptome, proteome). Identifying robust targets associated with exercise response, at both group and individual levels, is therefore important to develop health guidelines and targeted health interventions. MethodsTwenty, apparently healthy, moderately trained (VO2 max= 51.0{+/-}10.6 mL{middle dot}min-1{middle dot}kg-1) males (age range= 18-45yrs) from the Gene SMART (Skeletal Muscle Adaptive Responses to Training) study completed a 12-week High-Intensity Interval Training (HIIT) intervention. Muscle biopsies were collected at baseline and after 4, 8, and 12 weeks of HIIT. High throughput DNA methylation ([~]850 CpG sites), and proteomic ([~]3000 proteins) analyses were conducted at all-time points. Mixed-models were applied to estimate group and individual changes, and methylome and proteome integration was conducted using a holistic multilevel approach with the mixOmics package. ResultsSignificant shifts in the methylome (residual analysis) and proteome profiles were observed after 12 weeks of HIIT. 461 proteins significantly changed over time (at 4, 8, and 12 weeks), whilst only one differentially methylated position (DMP) was changed (adj.p-value <0.05). K-means analysis revealed clear protein clustering exhibiting similar changes over time. Individual responses to training were observed in 101 proteins. Seven proteins had a large effect-sizes >0.5, among them are two novel exercise-related proteins, LYRM7 and EPN1. Integration analysis uncovered bidirectional relationships between the methylome and proteome. ConclusionsWe showed a significant influence of HIIT on the epigenome and proteome in human muscle, and uncovered groups of proteins clustering according to similar patterns across the exercise intervention. Individual responses to exercise were observed in the proteome with novel mitochondrial and metabolic proteins consistently changed across individuals. Future work is required to elucidate the role of such proteins in response to exercise as well as to investigate the mechanisms associating genes and proteins in response to exercise.