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Transcriptional events in human skeletal muscle at the outset of concentric resistance exercise training

ABSTRACT: We sought to ascertain the time-course of transcriptional events that occur in human skeletal muscle at the outset of resistance exercise (RE) training in RE naïve individuals, and determine if the magnitude of any response was associated with exercise induced muscle damage. Sixteen RE naïve males were recruited, 8 underwent 2 sessions of 5x30 maximum, isokinetic knee extensions (180°.s-1) separated by 48 hrs. Muscle biopsies of the vastus lateralis were taken at baseline and 24 hrs after each exercise bout. Eight individuals acted as non-exercise controls with biopsies obtained at the same time intervals. Transcriptional changes were assessed by microarray, and binding of HSP27 and αB-crystallin to insoluble proteins by immunohistochemistry as a measure of muscle damage. In control subjects, no probesets were significantly altered (FDR<0.05) and HSP27 and αB-crystallin binding remained unchanged throughout the study. In exercised subjects, significant inter-subject variability following the initial bout of RE was observed in the muscle transcriptome, with greatest changes occurring when HSP27 and αB-crystallin binding was elevated. Following the second bout of RE, the transcriptome response was more consistent among subjects revealing a cohort of probesets associated with immune activation, the suppression of oxidative metabolism and protein ubiquitination as differentially regulated. The results reveal that the initial transcriptional response to RE is highly variable in RE naïve volunteers, is associated with muscle damage, and unlikely to reflect longer-term adaptations to RE training. These results highlight the importance of considering multiple time-points when determining the transcriptional response to RE and associated physiological adaptation.

ORGANISM(S): Homo sapiens

PROVIDER: GSE45426 | GEO | 2013/11/15

SECONDARY ACCESSION(S): PRJNA193700

REPOSITORIES: GEO

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Project description:We sought to ascertain the time-course of transcriptional events that occur in human skeletal muscle at the outset of resistance exercise (RE) training in RE naïve individuals, and determine if the magnitude of any response was associated with exercise induced muscle damage. Sixteen RE naïve males were recruited, 8 underwent 2 sessions of 5x30 maximum, isokinetic knee extensions (180°.s-1) separated by 48 hrs. Muscle biopsies of the vastus lateralis were taken at baseline and 24 hrs after each exercise bout. Eight individuals acted as non-exercise controls with biopsies obtained at the same time intervals. Transcriptional changes were assessed by microarray, and binding of HSP27 and αB-crystallin to insoluble proteins by immunohistochemistry as a measure of muscle damage. In control subjects, no probesets were significantly altered (FDR<0.05) and HSP27 and αB-crystallin binding remained unchanged throughout the study. In exercised subjects, significant inter-subject variability following the initial bout of RE was observed in the muscle transcriptome, with greatest changes occurring when HSP27 and αB-crystallin binding was elevated. Following the second bout of RE, the transcriptome response was more consistent among subjects revealing a cohort of probesets associated with immune activation, the suppression of oxidative metabolism and protein ubiquitination as differentially regulated. The results reveal that the initial transcriptional response to RE is highly variable in RE naïve volunteers, is associated with muscle damage, and unlikely to reflect longer-term adaptations to RE training. These results highlight the importance of considering multiple time-points when determining the transcriptional response to RE and associated physiological adaptation. 16 healthy male subjects were recruited and attended the laboratory fasted on 4 consecutive days. Biopsies from the vastus lateralis muscle were obtained on Days 0, 1 and 3, with total RNA extracted for gene expression analysis by microarray. During this period, 8 subjects performed isokinetic leg extension exercise using an isokinetic dynamometer (180 degrees per second; maximum intensity) on two occassions (days 0 and 2). Data for 7 exercise subjects presented in this study. 8 further subjects acted as non-exercised controls and did not participate in any exercise during the study period. A number of technical replicates were included and are identified in the sample list. Insufficient muscle biopsy sample or inadequate RNA quality accounted for 8 missing data points (TechRep1 N=40 as opposed to 48).

Project description:Massage therapy is commonly used for the physical rehabilitation of skeletal muscle to ameliorate pain and promote recovery from injury. While there is some evidence that massage may relieve pain in injured muscle, the cellular effects remain unknown. To assess the effects of massage, we administered either massage therapy or no treatment to separate quadriceps of eleven young, male participants after exercised-induced muscle damage. Muscle biopsies were acquired from the quadriceps (vastus lateralis) at baseline (rest), immediately after 10 minutes of massage treatment (0h), and after a 2.5 hour period of recovery. We found that massage activated the mechanotransduction signaling pathways FAK and Erk1/2, potentiated mitochondrial biogenesis signaling (nuclear PGC-1α), and mitigated the rise in NFkB (p65) nuclear accumulation caused by muscle trauma. Moreover, in spite of having no effect on muscle metabolites (glycogen, lactate), massage attenuated the production of the inflammatory cytokines TNF-α and IL-6 and reduced HSP27 phosphorylation, effectively mitigating cellular stress resulting from myofiber injury. In summary, massage therapy appears to be clinically beneficial when administered to acutely damaged skeletal muscle by reducing inflammation and promoting mitochondrial biogenesis. 55 muscle biopsies were used in this study as material to evaluate the effects of massage on gene expression. These biopsies were taken from the vastus lateralis of eleven healthy recreationally active males with full ethical approval at McMaster's university. Each individual had an initial biopsy at rest (baseline), followed by exercist testing for peak aerobic capacity. On a second visit, the individual performed a bout of exhaustive aerobic exercise, prior to recieving a randomized massage treatment to one leg. Immediatley following the exercise, subjects were allowed to recover for 10 minutes, while massage oil was lightly applied to both quadriceps. Then a single leg was randomized to recieve massage treatment for 10 minutes. Subjects then rested for 10 minutes, and one additional biopsies were carried out (on each leg). Two and half hours later (3 hours after the cessation of the exercise bout), 2 more biopsies were taken (one from each leg). This amounted to 5 biopsies from each individual.

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Transcriptional events in human skeletal muscle at the outset of concentric resistance exercise training

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