Biology subjects

Hiam, D.

Publications and source records attributed to Hiam, D..

5 recordsLinked to original sources

bioRxiv2023

Single-session measures of quadriceps neuromuscular function are reliable in healthy females and unaffected by age

ObjectiveThe inter-session reliability of a wide range of measures used to characterize the aging neuromuscular system is unknown, particularly in females. The aim of this study was to determine the inter-session reliability of quadriceps neuromuscular function assessed via maximal voluntary and evoked force and electromyography responses in healthy young and older females. MethodsTwenty-six females aged 19 - 74 years completed two identical testing sessions 9 {+/-} 7 days apart. Quadriceps neuromuscular function measurements included isometric maximal voluntary force (MVC), high and low frequency twitch force, voluntary and evoked electromyography (EMG) in superficial quadriceps (RMS, M-wave and H-reflex), and maximal torque (T0), velocity (V0) and power (PMAX) derived from torque-velocity and power-velocity relationships. Intra-class correlation coefficients (ICC), coefficients of variation (CoV) and Bland-Altman plots were used to assess inter-session reliability. The effect of participant age on inter-session reliability was assessed by linear regression. ResultsExcellent reliability (ICC > 0.8) was shown for all voluntary and evoked mechanical outcomes and systematic bias was essentially absent. Similarly, all vastus lateralis EMG outcomes showed excellent reliability (ICC > 0.8) with CoVs < 12%, which were better than vastus medialis and rectus femoris outcomes. Participant age was not associated with inter-session reliability (P > 0.05). ConclusionExcellent reliability of voluntary and evoked force and vastus lateralis EMG outcomes measured in healthy females can be attained in one testing session, irrespective of age, increasing feasibility for future research. The random error should however be considered when quantifying age-related differences and/or adaptation to exercise in female neuromuscular function. New and NoteworthyThe test-retest reliability of a diverse range of measures used to quantify neuromuscular function were assessed in younger and older females for the first time. We show that reliable measures of maximal voluntary and evoked quadriceps force and electromyography outcomes can be obtained in one testing session, irrespective of participant age. Thus, neuromuscular function can be accurately assessed across the female lifespan with minimal inconvenience imposed on participants, increasing feasibility for future research.

physiology↗

bioRxiv2023

The influence of Sex on microRNA expression in Human Skeletal Muscle

IntroductionSex differences in microRNA (miRNA) expression profiles have been found across multiple tissues. Skeletal muscle is one of the top tissues that underpin sex-based differences, yet there is limited research into whether there are sex differences in miRNA expression in skeletal muscle. Further, there is limited literature investigating potential differences between males and females in skeletal muscle miRNA expression following exercise, a well-known modulator of miRNA expression. Therefore, the aim of this study was to investigate the effect of sex on miRNA expression in skeletal muscle at baseline and after an acute bout of exercise. MethodsMiRNAs were measured using Taqman(R)miRNA arrays in skeletal muscle of 42 healthy participants from the GeneSMART study (24 males and 20 females aged 18-45 yrs). Differentially expressed miRNAs were identified using mixed linear models adjusted for age. Experimentally validated miRNA gene targets enriched in skeletal muscle were identified in-silico. Over representation analysis was conducted to identify enriched pathways. TransmiR V.2 was used to identify transcription factor (TF)-miR regulatory networks using CHIP-derived data. We further profiled the effects of two sex-biased miRNAs overexpressed in human primary muscle cells lines derived from male and female donors to understand the transcriptome targeted by these miRNAs and investigate and potential sex-specific effects. ResultsA total of 80 miRNAs were differentially expressed in skeletal muscle between the sexes, with 61 miRNAs responding differently to the exercise between the sexes. Sex-biased miRNA gene targets were enriched for muscle-related processes including proliferation and differentiation of the muscle cells and numerous metabolic pathways, suggesting that miRNAs are playing a role in programming sex differences in skeletal muscle. Over-expression of sex-biased miRNAs miRNA-30a and miRNA-30c resulted in profound changes to gene expression profiles that were partly specific to the sex of the cell donor in human primary skeletal muscle cells. ConclusionWe found sex-differences in the expression profile of skeletal muscle miRNAs at baseline and in response to exercise. These miRNAs target regulatory pathways essential to skeletal muscle development and metabolism, suggesting that miRNAs play a profound but highly complex role in programming sex-differences in the skeletal muscle phenotype.

physiology↗

bioRxiv2022

The effect of the menstrual cycle on the circulating microRNA pool in human plasma: a pilot study

Study questionDo ovarian hormones levels influence cf-miRNA expression across the menstrual cycle? Summary answerMeasures of ovarian hormones should be rigorously included in future studies assessing cf-miRNA expression in females and used as time-varying confounders. This exploratory study suggests that cf-miRNAs may play an active role in the regulation of the female cycle in various target tissues. What is known alreadyCell-free or "circulating" miRNAs (cf-miRNAs) are secreted from tissues into most physiological fluids, including plasma, where they play a role in cross-tissue communication. Endogenous and exogenous factors, including sex hormones, regulate cellular miRNA expression levels. Plasma cf-miRNA levels vary with numerous pathological and physiological conditions, including in females. Participants/materials, setting, methodsWe conducted an exploratory study where blood samples were collected from sixteen eumenorrheic females in the early follicular phase, the ovulation phase and the mid-luteal phase of the menstrual cycle. Ovarian hormones oestrogen, progesterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured in serum by electrochemiluminescence. The expression levels of 179 plasma-enriched miRNAs were profiled using a PCR-based panel, including stringent internal and external controls to account for the potential differences in RNA extraction and reverse-transcription stemming from low-RNA input samples. Study design, size, durationThis was a prospective monocentric study conducted between March and November 2021. Main results and the role of chanceThis exploratory study suggests that cf-miRNAs may play an active role in the regulation of the female cycle in various target tissues. Linear mixed-models adjusted for the relevant variables showed numerous associations between phases of the menstrual cycle, ovarian hormones and plasma cf-miRNA levels. Validated gene targets of the cf-miRNAs varying with the menstrual cycle were enriched within the female reproductive tissues and primarily involved in cell proliferation and apoptosis. Wider implications of the findingsMeasures of ovarian hormones should be rigorously included in future studies assessing cf-miRNA expression in females and used as time-varying confounders. Limitations, reasons for cautionOur study was conducted on a relatively small cohort of patients. However, it was tightly controlled for endogenous and exogenous confounders, which is critical to ensure robust and reproducible cf-miRNA research. Wider implications of the findingsOur results reinforce the importance of accounting for female-specific biological processes in physiology research by implementing practical or statistical mitigation strategies during data collection and analysis. Study funding/competing interest(s)This study was supported by the clinique romande de readaptation, Sion, Switzerland. Prof. Severine Lamon, is supported by an Australian Research Council Future Fellowship (FT10100278). The authors declare no competing interest Trial registration numberN/A.

physiology↗

bioRxiv2022

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.

molecular biology↗

bioRxiv2021

Genome-wide DNA methylation and transcriptome integration reveal distinct sex differences in skeletal muscle.

Nearly all human complex traits and diseases exhibit some degree of sex differences, with epigenetics being one of the main contributing factors. Various tissues display sex differences in DNA methylation, however this has not yet been explored in skeletal muscle, despite skeletal muscle being among the tissues with the most transcriptomic sex differences. For the first time, we investigated the effect of sex on autosomal DNA methylation in human skeletal muscle across three independent cohorts (Gene SMART, FUSION, and GSE38291) using a meta-analysis approach, totalling 369 human muscle samples (222 males, 147 females), and integrated this with known sex-biased transcriptomics. We found 10,240 differentially methylated regions (DMRs) at FDR < 0.005, 94% of which were hypomethylated in males, and gene set enrichment analysis revealed that differentially methylated genes were involved in muscle contraction and substrate metabolism. We then investigated biological factors underlying DNA methylation sex differences and found that circulating hormones were not associated with differential methylation at sex-biased DNA methylation loci, however these sex-specific loci were enriched for binding sites of hormone-related transcription factors (with top TFs including androgen (AR), estrogen (ESR1), and glucocorticoid (NR3C1) receptors). Fibre type proportions were associated with differential methylation across the genome, as well as across 16 % of sex-biased DNA methylation loci (FDR < 0.005). Integration of DNA methylomic results with transcriptomic data from the GTEx database and the FUSION cohort revealed 326 autosomal genes that display sex differences at both the epigenome and transcriptome levels. Importantly, transcriptional sex-biased genes were overrepresented among epigenetic sex-biased genes (p-value = 4.6e-13), suggesting differential DNA methylation and gene expression between male and female muscle are functionally linked. Finally, we validated expression of three genes with large effect sizes (FOXO3A, ALDH1A1, and GGT7) in the Gene SMART cohort with qPCR. GGT7, involved in antioxidant metabolism, displays male-biased expression as well as lower methylation in males across the three cohorts. In conclusion, we uncovered 8,420 genes that exhibit DNA methylation differences between males and females in human skeletal muscle that may modulate mechanisms controlling muscle metabolism and health. SignificanceThe importance of uncovering biological sex differences and their translation to physiology has become increasingly evident. Using a large-scale meta-analysis of three cohorts, we perform the first comparison of genome-wide skeletal muscle DNA methylation between males and females, and identify thousands of genes that display sex-differential methylation. We then explore intrinsic biological factors that may be underlying the DNA methylation sex differences, such as fibre type proportions and sex hormones. Leveraging the GTEx database, we identify hundreds of genes with both sex-differential expression and DNA methylation in skeletal muscle. We further confirm the sex-biased genes with gene expression data from two cohorts included in the methylation meta-analysis. Our study integrates genomewide sex-biased DNA methylation and expression in skeletal muscle, shedding light on distinct sex differences in skeletal muscle.

genomics↗