Physical exercise-associated gene expression signatures in peripheral blood

Effect of 8-week of dietary micronutrient supplementation on gene expression in elite handball athletes

Purpose

A study was made of the changes in gene expression in elite handball athletes, comparing gene modulation before, after and in the absence of an 8-week nutritional intervention with multivitamin/mineral supplements.

Methods

Thirteen elite handball athletes (aged 22.9 ± 2.7 years) and 13 sedentary controls (aged 20.9 ± 2.8 years) were included. Three timepoints were established: T0 (baseline conditions); T8 (after 8 weeks of supplementation with a multivitamin/mineral complex); and T16 (after 8 weeks in the absence of supplementation). The expressions of a total 112 of genes were evaluated by RT-qPCR analysis with the QuantStudioTM 12K Flex Real-Time PCR System.

Results

The analysis revealed different gene regulation profiles of genes implicated in cell communication, cell energy metabolism, inflammation and the immune system, oxidative stress and muscle function in athletes compared to sedentary controls under resting conditions (upregulated genes: effect size = large, ƞ2 = 1.011 to 1.398, p < 0.05; downregulated genes: effect size = large, ƞ2 = 0.846 and 1.070, p < 0.05, respectively). The nutritional intervention encouraged gene upregulation in elite athletes (p < 0.05). In a follow-up investigation, the IRAK1, CD81, ITGB1, ACADS PDHA2 and GPX1 genes were downregulated in athletes, with a moderate main effect for time-by-group interaction (ηP2 = 0.099 to 0.133; p < 0.05). Additionally, nutritional genes such as MTHFR and THTPA revealed a moderate effect over all the timepoints and group interaction in the study (ηP2 = 0.070 to 0.092; p < 0.05).

Conclusions

Elite handball athletes showed a different expression profile in reference to key genes implicated in several sports performance-related functions compared to the sedentary controls, in addition to modulation of gene expression after multivitamin/mineral supplementation.

The Genetics of Physical Activity

PURPOSE OF REVIEW

Physical activity (PA) is a well-established modifiable lifestyle determinant for multiple cardio-metabolic outcomes. While many psychosocial and environmental correlates of PA have been identified, current understanding of the genetic architecture that contributes to PA is still very limited, especially when compared to other phenotypes such as obesity and diabetes.

RECENT FINDINGS

This review systematically and comprehensively assesses available evidence from animal experiments, family studies, population-based candidate gene analyses, and genome-wide association studies (GWAS) studying the genetics of physical activity patterns. It discusses the scientific evolution in the field of PA genetics, including the recognition of increased sample sizes, the shift from early family-based approaches to association-based design, and the rapidly advancement of enabling genotyping and sequencing technologies. In addition, this review points to the gaps in the current knowledge base, including the general lack of GWAS and whole-genome sequence analyses particularly understudied populations, and the need for large-scale collaborative effort in both observational and experimental settings. In this review, we also call for research utilizing systems biology strategies for PA genetic research and accounting for complex gene-environment interactions that may vary by race/ethnicity. The epidemic of physical inactivity has been a public health nemesis, encompassing a large burden of diseases and high societal costs. A better understanding of the genetic basis of PA can inform public health policies for the prevention, control, and treatment of many chronic diseases related to physical inactivity.

Transcription of LINE-derived sequences in exercise-induced stress in horses

A large proportion of mammalian genomes is represented by transposable elements (TE), most of them being long interspersed nuclear elements 1 (LINE-1 or L1). An increased expression of LINE-1 elements may play an important role in cellular stress-related conditions exerting drastic effects on the mammalian transcriptome. To understand the impact of TE on the known horse transcriptome, we masked the horse EST database, pointing out that the amount is consistent with other major vertebrates. A previously developed transcript-derived fragments (TDFs) dataset, deriving from exercise-stimulated horse peripheral blood mononuclear cells (PBMCs), was found to be enriched with L1 (26.8% in terms of bp). We investigated the involvement of TDFs in exercise-induced stress through bioinformatics and gene expression analysis. Results indicate that LINE-derived sequences are not only highly but also differentially expressed during physical effort, hinting at interesting scenarios in the regulation of gene expression in relation to exercise.

PBMCs express a transcriptome signature predictor of oxygen uptake responsiveness to endurance exercise training in men

Peripheral blood cells are an accessible environment in which to visualize exercise-induced alterations in global gene expression patterns. We aimed to identify a peripheral blood mononuclear cell (PBMC) signature represented by alterations in gene expression, in response to a standardized endurance exercise training protocol. In addition, we searched for molecular classifiers of the variability in oxygen uptake (V̇o2). Healthy untrained policemen recruits (n = 13, 25 ± 3 yr) were selected. Peak V̇o2 (measured by cardiopulmonary exercise testing) and total RNA from PBMCs were obtained before and after 18 wk of running endurance training (3 times/wk, 60 min). Total RNA was used for whole genome expression analysis using Affymetrix GeneChip Human Gene 1.0 ST. Data were normalized by the robust multiarray average algorithm. Principal component analysis was used to perform correlations between baseline gene expression and V̇o2peak. A set of 211 transcripts was differentially expressed (ANOVA, P < 0.05 and fold change > 1.3). Functional enrichment analysis revealed that transcripts were mainly related to immune function, cell cycle processes, development, and growth. Baseline expression of 98 and 53 transcripts was associated with the absolute and relative V̇o2peak response, respectively, with a strong correlation (r > 0.75, P < 0.01), and this panel was able to classify the 13 individuals according to their potential to improve oxygen uptake. A subset of 10 transcripts represented these signatures to a similar extent. PBMCs reveal a transcriptional signature responsive to endurance training. Additionally, a baseline transcriptional signature was associated with changes in V̇o2peak. Results might illustrate the possibility of obtaining molecular classifiers of endurance capacity changes through a minimally invasive blood sampling procedure.

Dexamethasone stimulated gene expression in peripheral blood indicates glucocorticoid-receptor hypersensitivity in job-related exhaustion

Work-related stress can lead to various health problems ranging from job-related exhaustion to psychiatric and somatic diseases. Biomarkers of job-related exhaustion could help to improve our understanding of the biological mechanisms and might be useful to guide prevention and treatment strategies. The present study included 12 male cases suffering from job-related exhaustion and 12 matched healthy controls. Severity of exhaustion was assessed with the Maslach Burnout Inventory (MBI) and the Shirom-Melamed Burnout Measure (SMBM). Whole genome expression profiles derived from whole blood cells (baseline and following glucocorticoid-receptor (GR) stimulation with 1.5mg dexamethasone p.o.) and corresponding plasma cortisol levels were analyzed. All cases participated in regular aerobic exercise for 12 consecutive weeks and were then re-assessed at follow-up for exhaustion symptoms as well as for cortisol levels and gene expression profiles. At baseline, we found increased basal cortisol levels and an enhanced suppression of plasma cortisol concentrations following dexamethasone in cases suffering from job-related exhaustion. Gene expression analysis revealed that 1.6-fold more transcripts were significantly regulated by dexamethasone in cases as compared to controls. At follow-up after 12 weeks of regular exercise training which was accompanied by significantly improved exhaustion severity scores, cortisol levels and gene expression profiles of cases normalized to the levels observed in controls. In conclusion, we detected GR-induced neuroendocrine and gene expression changes in cases suffering from job-related exhaustion which are in line with an increased sensitivity of GR function. This GR dysregulation normalized with symptom recovery.

Whole blood transcriptomics and urinary metabolomics to define adaptive biochemical pathways of high-intensity exercise in 50-60 year old masters athletes

Exercise is beneficial for a variety of age-related disorders. However, the molecular mechanisms mediating the beneficial adaptations to exercise in older adults are not well understood. The aim of the current study was to utilize a dual approach to characterize the genetic and metabolic adaptive pathways altered by exercise in veteran athletes and age-matched untrained individuals. Two groups of 50–60 year old males: competitive cyclists (athletes, n = 9; VO_2peak 59.1±5.2 ml·kg⁻¹·min⁻¹; peak aerobic power 383±39 W) and untrained, minimally active individuals (controls, n = 8; VO_2peak 35.9±9.7 ml·kg⁻¹·min⁻¹; peak aerobic power 230±57 W) were examined. All participants completed an acute bout of submaximal endurance exercise, and blood and urine samples pre- and post-exercise were analyzed for gene expression and metabolic changes utilizing genome-wide DNA microarray analysis and NMR spectroscopy-based metabolomics, respectively. Our results indicate distinct differences in gene and metabolite expression involving energy metabolism, lipids, insulin signaling and cardiovascular function between the two groups. These findings may lead to new insights into beneficial signaling pathways of healthy aging and help identify surrogate markers for monitoring exercise and training load.

Genome-wide association study of exercise behavior in Dutch and American adults

INTRODUCTION

The objective of this study was to identify genetic variants that are associated with adult leisure time exercise behavior using genome-wide association (GWA) in two independent samples.

METHODS

Exercise behavior was measured in 1644 unrelated Dutch and 978 unrelated American adults of European ancestry with detailed questions about type, frequency, and duration of exercise. Individuals were classified into regular exercisers or nonexercisers using a threshold of 4 MET·h (metabolic equivalents-hours per week). GWA analyses of ∼1.6 million observed and imputed Single Nucleotide Polymorphism (SNP) were conducted in both samples independently using logistic regression in SNPTEST, including sex, age, and body mass index as covariates. A meta-analysis of the results was performed using the weighted inverse variance method in METAL.

RESULTS

Thirty-seven novel SNPs in the PAPSS2 gene and in two intergenic regions on chromosomes 2q33.1 and 18p11.32 were associated with exercise participation (pooled P values <1.0 × 10(-5)). Previously reported associations (ACE, CASR, CYP19A1, DRD2, LEPR, and MC4R genes) or linkage findings (2p22.3, 4q28, 4q31.21 7p13, 9q31, 11p15, 13q22, 15q13, 18q12.2, 18q21.1, 19p13.3, and 20q12) were not replicated, although suggestive evidence was found for association to rs12405556 in the LEPR gene (pooled P value 9.7 × 10(-4); American sample, P value 9.8 × 10(-5)) and for association to rs8036270 in the GABRG3 gene (pooled P value 4.6 × 10(-5)) in the linkage region 15q12-13.

CONCLUSIONS

The heritability of leisure time exercise behavior is likely to be accounted for by many genetic variants with small effect size. These can be detected by GWA as was shown here for the PAPSS2 gene, but larger samples with genome-wide genotypes and high-quality exercise data are needed for further progress.

Assessing the human immune system through blood transcriptomics

Blood is the pipeline of the immune system. Assessing changes in transcript abundance in blood on a genome-wide scale affords a comprehensive view of the status of the immune system in health and disease. This review summarizes the work that has used this approach to identify therapeutic targets and biomarker signatures in the field of autoimmunity and infectious disease. Recent technological and methodological advances that will carry the blood transcriptome research field forward are also discussed.

Effect of exercise on gene expression profile in unfractionated peripheral blood leukocytes

A 4-h bout of exercise induces immunomodulatory effects. Peripheral blood was withdrawn before, and at 4, 8 and 24h after the start of exercise. RNA from the unfractionated white blood cells was analyzed using Agilent human 44K microarray. The expression profiles were sorted into seven clusters based on their unique time-dependent kinetics. In a separate experiment, cell-specific markers were collected and compared among the members in each cluster. Two clusters were assigned as representing neutrophils, one as NK cells, and another mostly as T cells. Three clusters seemed to be mixtures of several cell types. Extension of this approach to other systems is discussed.