Skeletal muscle proteomics responses in men and women during acute exercise-heat stress and acclimation
Authors: Struder Jeb F. , Szymanski Michael R. , Mahoney Kyle J. , Thornton Staci N. , Edgar Cory M. , Kwon Oh Sung , Huggins Robert A. 
Published: May 2024

Purpose: Our broad aim was to identify targetable mechanisms of improving skeletal muscle function and recovery during exercise-heat stress. In this study, we used proteomics to test the hypothesis that skeletal muscle proteomic changes would correspond to acclimation state. Methods: Healthy men (M: n = 7, 22 ± 2 yo, VO2max 52.86 ± 2.35 ml·kg−1·min−1) and women (F: n = 7, 24 ± 1 yo, VO2max 45.97 ± 2.57 ml·kg−1·min−1) completed a 5-day heat acclimation (HA) (40 °C, 40% rH). Before and after HA, participants completed a heat tolerance test measuring time to reach rectal temperature 39.5°C (HTT39.5) or failure (stoppage). Musculoskeletal biopsies from the vastus lateralis were harvested for protein extraction, quantification, and digestion prior to untargeted UPLC-MS/MS (Q Exactive HF). Peptide identification and label-free quantitation was achieved using Andromeda search engine and MaxQuant (v1.6.10.43), using UniProt reference proteome UP0000005640. All search results were filtered to FDR (false discovery rate) 1% and uploaded to Scaffold v5.1.0 for data visualization and t-test analyses for difference between conditions (p < 0.05). Functional annotation and pathway analysis were conducted (DAVID, Reactome, String). Physiological, perceptual, and performance metrics were statistically analyzed using t-tests (p ≤ 0.05). Results: No significant differences (p = 0.931) were observed between males (mean = 27.21 ± 1.37 minutes) and females (26.91 ± 3.20 minutes) for PREHA HTT39.5. HTT39.5 for F was significantly higher than for men at PREHA (p = 0.001) and POSTHA (p = 0.014). 2741 proteins from 960,731 spectra were detected among our skeletal muscle biopsy samples with 22 and 33 proteins expressed more highly in M and F at PREHA, respectively. 149 and 81 proteins were more highly expressed in M and F, respectively, at POSTHA. Differences between M and F included more highly connected nodes in M at PREHA (average node degree: 3.7, avg. local clustering coeffcient: 0.529, PPI enrichment p-value < 1.11e-16, HIST1H3 (isoforms D, H, and J), HIST1H4F, HIST2H2A (isoforms C, B, and E), HIST2HAC, H2AFX) and at POSTHA (average node degree: 4.26, avg. local clustering coeffcient: 0.455, expected number of edges 110, PPI enrichment p-value < 1.0e-16, GAPDH, RPS13, TPI1, PKM, RPS21). Differences in F and M (more highly expressed) also included GO terms related to DNA, RNA, and protein quality regulation and immune function and metabolism (p < 0.05). Conclusions: Acclimation is associated with different skeletal muscle responses in M and F related to protein synthesis and immune function pathways that are regulated after a bout of exercise-heat stress. Ongoing analysis examines relationships between naïve or acclimated state and individual skeletal muscle proteomic profiles. DoD BA200299. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.