Project description:Inadequate protein intake initiates an accommodative response with adverse changes in skeletal muscle function and structure. mRNA level changes due to short-term inadequate dietary protein might be an early indicator of accommodation. The aims of this study were to assess the effects of dietary protein and the diet-by-age interaction on the skeletal muscle transcript profile. Self-organizing maps were used to determine expression patterns across protein trials. 958 transcripts were differentially expressed (P<0.05) with diet and 853 had a diet-by-age interaction (P<0.05) using ANOVA. The results for diet alone revealed that P63 was associated with up-regulation of transcripts related to ubiquitin-dependent protein catabolism and muscle contraction and P63 and P94 resulted in up-regulation of transcripts related to apoptosis and down-regulation of transcripts related to cell differentiation; muscle and organ development; extracellular space; and responses to stimuli and stress. The diet-by-age expression patterns demonstrated that across the three protein trials transcripts related to protein metabolism were affected by age. Changes in skeletal muscle mRNA levels in the younger and older males to protein intake near or below the RDA are indicative of an early accommodative response. 5052 transcripts were determined as differentially expressed (P<0.05) between the younger and older males, of which 2556 met the False Discovery Rate correction (P=0.0081). The age-related changes in the transcript profile were consistent with aging skeletal muscle phenotypes including; mitochondrial dysfunction (UP- and DOWN-regulation), RNA splicing (UP), oxidative stress (UP), apoptosis (UP), and energy metabolism (DOWN). Experiment Overall Design: 22 healthy free-living younger (21-43 y, n=12) and older (63-79 y, n=10) males completed three controlled feeding trials with protein intakes of 63% (P63: 0.50 g/kg), 94% (P94: 0.75 g/kg), and 125% (P125: 1.00 g/kg) of the recommended dietary allowance (RDA). A fasting state vastus lateralis biopsy was taken from the dominant leg of each subject on day 12 of each trial following an overnight fast. Total RNA was isolated from the muscle samples using Tri-Reagent and the manufacture's protocol.
Project description:Inadequate dietary protein intake causes adverse changes in the morphology and function of skeletal muscle. These changes may be reflected in early alterations in muscle mRNA levels. Microarray analysis was used to assess whether inadequate protein intake differentially affects skeletal muscle transcript levels and expression profiles in older adults. Experiment Overall Design: 11 older males and females (aged 55-80 y) consumed controlled diets that contained 1.2 g proteinâ¢kg-1â¢d-1 (adequate protein) for one wk and then 0.5 g proteinâ¢kg-1â¢d-1 (inadequate protein; IP group; n=11) for a second wk. RNA was isolated from fasting-state vastus lateralis biopsies obtained at the end of each period and the transcript levels were determined using the Affymetrix U133A array
Project description:Inadequate dietary protein intake causes adverse changes in the morphology and function of skeletal muscle. These changes may be reflected in early alterations in muscle mRNA levels. Microarray analysis was used to assess whether inadequate protein intake differentially affects skeletal muscle transcript levels and expression profiles in older adults. Keywords: dietary intake response
Project description:Inadequate protein intake initiates an accommodative response with adverse changes in skeletal muscle function and structure. mRNA level changes due to short-term inadequate dietary protein might be an early indicator of accommodation. The aims of this study were to assess the effects of dietary protein and the diet-by-age interaction on the skeletal muscle transcript profile. Self-organizing maps were used to determine expression patterns across protein trials. 958 transcripts were differentially expressed (P<0.05) with diet and 853 had a diet-by-age interaction (P<0.05) using ANOVA. The results for diet alone revealed that P63 was associated with up-regulation of transcripts related to ubiquitin-dependent protein catabolism and muscle contraction and P63 and P94 resulted in up-regulation of transcripts related to apoptosis and down-regulation of transcripts related to cell differentiation; muscle and organ development; extracellular space; and responses to stimuli and stress. The diet-by-age expression patterns demonstrated that across the three protein trials transcripts related to protein metabolism were affected by age. Changes in skeletal muscle mRNA levels in the younger and older males to protein intake near or below the RDA are indicative of an early accommodative response. 5052 transcripts were determined as differentially expressed (P<0.05) between the younger and older males, of which 2556 met the False Discovery Rate correction (P=0.0081). The age-related changes in the transcript profile were consistent with aging skeletal muscle phenotypes including; mitochondrial dysfunction (UP- and DOWN-regulation), RNA splicing (UP), oxidative stress (UP), apoptosis (UP), and energy metabolism (DOWN). Keywords: Age and dietary protein response
Project description:Shatavari is a herbal dietary supplement that may increase skeletal muscle strength in younger and older adults. Shatavari contains compounds with both estradiol-like and antioxidant properties, which could enhance muscle function. Postmenopausal women may derive the greatest benefit, as estrogen deficiency adversely impacts skeletal muscle function. However, mechanistic insights are limited and the effects of shatavari on muscle function require further characterization. In this randomised, double-blind trial, 17 young (23 ±5yr) and 22 older (63±5yr) women completed an eight-week leg resistance training programme. They consumed either a placebo or shatavari (1000mg/d, equivalent to 26,500 mg/d fresh weight) supplement throughout. Pre and post training, measures of leg strength, neuromuscular function and vastus lateralis (VL) biopsies were obtained. Tandem-mass-tagged VL proteomic analyses were performed. Additionally, resistance training (RT) is the gold standard intervention for ameliorating sarcopenia. Outstanding mechanistic questions remain regarding the malleability of the molecular determinants of skeletal muscle function in older age. Discovery proteomics can expand such knowledge. We further aimed to compare the effect of RT on the skeletal muscle proteome and neuromuscular function (NMF) in older and younger women.
Project description:Human aging is associated with skeletal muscle atrophy and functional impairment (sarcopenia). Multiple lines of evidence suggest that mitochondrial dysfunction is a major contributor to sarcopenia. We evaluated whether healthy aging was associated with a transcriptional profile reflecting mitochondrial impairment and whether resistance exercise could reverse this signature to that approximating a younger physiological age. Skeletal muscle biopsies from healthy older (N = 25) and younger (N = 26) adult men and women were compared using gene expression profiling, and a subset of these were related to measurements of muscle strength. 14 of the older adults had muscle samples taken before and after a six-month resistance exercise-training program. Before exercise training, older adults were 59% weaker than younger, but after six months of training in older adults, strength improved significantly (P<0.001) such that they were only 38% lower than young adults. As a consequence of age, we found 596 genes differentially expressed using a false discovery rate cut-off of 5%. Prior to the exercise training, the transcriptome profile showed a dramatic enrichment of genes associated with mitochondrial function with age. However, following exercise training the transcriptional signature of aging was markedly reversed back to that of younger levels for most genes that were affected by both age and exercise. We conclude that healthy older adults show evidence of mitochondrial impairment and muscle weakness, but that this can be partially reversed at the phenotypic level, and substantially reversed at the transcriptome level, following six months of resistance exercise training. Keywords: resistance exercise, muscle, aging
Project description:Transcript data from quadriceps skeletal muscle from fasted-state male BXD strains on Quadriceps, Chow or Quadriceps, High fat diet We used microarrays to compare the skeletal muscle expression differences across males in the BXD strain family and across two diverse diets