The Effects Of Short-term Altitude Resistance Exercise On Skeletal Muscle And The Construction Of Biomolecular Regulatory Networks

Purpose:To explore the effect of short-term altitude resistance exercise on skeletal muscle and further understand of the molecular mechanisms, we used the technology of microarray and bioinformatics to investigate the genes differentially expressed after altitude resistance exercise and the construct biomolecular regulatory networks.Methods:Nine participants had a 10-day normoxic resistance exercise at sea level to confirm the effectiveness of the training program, which was refered to ACSM’S Guidelines for Exercise Testing and Prescriptio. Twelve male volunteers participated in this study, which were randomly divided into the control group (C, n=6) and the resistance exercise group (HR, n=6) stayed at 3,700 m above sea level for a period of 10 days. The exercise program was same as the one that performed at sea level. Magnetic Resonance Imaging, dual-energy X-ray absorptiometry and IOSMED2000 muscle strength testing system were used to measure the cross-sectional area (CSA) of thigh, body composition and muscle strength respectively. Muscle samples were obtained from the vastus’lateralis by biopsies and Agilent mRNA Array was used to analysis the differentially expressed genes. Bioinformatics methods were used in function annotation, pathway analysis, transcription factors forecast and construction of biomolecular regulatory networks. The validation of microarray was analyzed by real-time fluorescence quantitative RT-PCR assay and the protein expression of the crucial proteins in biomolecular regulatory networks were examined by WB analysis.Results:(1) Total lean mass and muscle strength significantly increased after 10 days’ resistance exercise. (2) Total lean mass, leg lean mass and leg muscle CSA significantly decreased in C group. (3) The results of gene array (≥1.5 fold, p<0.05):the differential expression of 192 up-regulated and 240 down-regulated mRNAs reached statistical significance after altitude resistance exercise. The differentially expressed genes involved in cell cycle, hormone stimulus, response to oxi dative stress, muscle growth and protein metabolic process. (4) FOXO, insulin and ErbB pathways were found by KEGG, which were associated with skeletal muscle size. (5) The effect of altitude exposure on skeletal muscle might have a relationship with transcription factor Nkx2-5, which was crucial to the network. (6) MYC, SMAD3, MAPK1 and ERBB2, which were vital for the surveillance of the PPI network. (7) In gene co-expression network, nine genes (MARK13, ACAT1, NDUFS1, TM0D4, MYOT, TUSC2, PTP4A1, GLI3 and EIF4B) possessed important regulatory ability involved in the biological process of muscle development, respiratory chain in mitochondrial and muscle contraction, which could be associated with anti atrophy.Conclusion:(1) Altitude resistance exercise could be an effective countermeasure against muscle wasting caused by altitude exposure; (2) The molecular mechanism of anti atrophy after altitude resistance could be related to FOXO, ErbB pathway and down regulated genes of FOXO1, SMAD3; (3) In regulatory networks, Nkx2-5, SMAD3, MAPK1, MYC, ERBB2, MAPK13, MYOT, EIF4B, TM0D4, GLI3, ACAT1, TUSC2, PTP4A1 and NDUFS1 played an important role in maintaining skeletal muscle after altitude resistance exercise.