Project description:Muscle mass and strength reduce during ageing with a steeper decline in women around the age of 50, which suggests that the menopausal transition is one of the mechanisms for age-induced neuromuscular deteriorations. At the moment, there is no clear explanation for the decline in muscle properties although both physical exercise and maintaining near premenopausal estrogen levels by hormonal replacement have been helpful in their preservation. However, the molecular consequences of both treatments in skeletal muscle are mostly unknown. The goal of this genome-wide study was to investigate the transcriptional networks through which power training (PT) comprising of jumping activities and estrogen containing hormone replacement therapy (HRT) may aid in the prevention of functional limitation ensued from insufficient muscle mass and physical performance after menopause. We used m. vastus lateralis samples obtained from postmenopausal women participating in a yearlong randomized double-blinded placebo-controlled trial with PT and HRT interventions. Muscle samples were available from eight PT, ten HRT and nine control women. Women in the PT group participated in a progressive PT program comprising mostly of jumping exercises for lower limbs with additional resistance exercises for the upper body. HRT intervention was double-blinded. All participants used either estradiol/noretisterone acetate preparation or placebo. Using statistical threshold p-value <0.05 and |fold change| >1.2 we identified 665 genes being differentially expressed among the studied 50-57-yr-old postmenopausal women. We used the hierarchical clustering method with extensive enrichment analysis in order to reveal enrichment of known GO or KEGG functional categories among co-regulated gene-clusters. In the enrichment analysis false discovery rate was set to be less than 15%. Transcription of “response to contraction”-, “insulin signaling”- and “adipocytokine signaling”-genes were upregulated by PT. Both PT and HRT were similarly effective on transcriptional regulation of glycolytic energy metabolism and calcium signaling. The HRT specifically affected “mitochondrion”-genes. In addition, we identified functional categories, such as “muscle development”, which were changed during the trial in all study groups. Our study revealed transcriptional changes in several functional categories in thigh muscle tissue of early postmenopausal women. The results emphasize that during the first years of the postmenopausal period, muscle properties are under transcriptional modulation, which both PT and HRT partially counteract leading to preservation of muscle mass and performance. More specifically, our findings indicate that PT and HRT may function through improving energy metabolism, improving the response to contraction, preserving functionality of mitochondria and reducing reorganization of muscle tissue. Therefore these treatments are recommended for preservation of adequate muscle mass and function. 54 samples, which formed 3 study groups with 2 timepoints, i.e., 8 power training subjects, 10 hormone replacement subjects and 9 controls. 6 control subjects had replicated samples resulting in a total of 60 hybridizations.

Project description:Muscle mass and strength reduce during ageing with a steeper decline in women around the age of 50, which suggests that the menopausal transition is one of the mechanisms for age-induced neuromuscular deteriorations. At the moment, there is no clear explanation for the decline in muscle properties although both physical exercise and maintaining near premenopausal estrogen levels by hormonal replacement have been helpful in their preservation. However, the molecular consequences of both treatments in skeletal muscle are mostly unknown. The goal of this genome-wide study was to investigate the transcriptional networks through which power training (PT) comprising of jumping activities and estrogen containing hormone replacement therapy (HRT) may aid in the prevention of functional limitation ensued from insufficient muscle mass and physical performance after menopause. We used m. vastus lateralis samples obtained from postmenopausal women participating in a yearlong randomized double-blinded placebo-controlled trial with PT and HRT interventions. Muscle samples were available from eight PT, ten HRT and nine control women. Women in the PT group participated in a progressive PT program comprising mostly of jumping exercises for lower limbs with additional resistance exercises for the upper body. HRT intervention was double-blinded. All participants used either estradiol/noretisterone acetate preparation or placebo. Using statistical threshold p-value <0.05 and |fold change| >1.2 we identified 665 genes being differentially expressed among the studied 50-57-yr-old postmenopausal women. We used the hierarchical clustering method with extensive enrichment analysis in order to reveal enrichment of known GO or KEGG functional categories among co-regulated gene-clusters. In the enrichment analysis false discovery rate was set to be less than 15%. Transcription of “response to contraction”-, “insulin signaling”- and “adipocytokine signaling”-genes were upregulated by PT. Both PT and HRT were similarly effective on transcriptional regulation of glycolytic energy metabolism and calcium signaling. The HRT specifically affected “mitochondrion”-genes. In addition, we identified functional categories, such as “muscle development”, which were changed during the trial in all study groups. Our study revealed transcriptional changes in several functional categories in thigh muscle tissue of early postmenopausal women. The results emphasize that during the first years of the postmenopausal period, muscle properties are under transcriptional modulation, which both PT and HRT partially counteract leading to preservation of muscle mass and performance. More specifically, our findings indicate that PT and HRT may function through improving energy metabolism, improving the response to contraction, preserving functionality of mitochondria and reducing reorganization of muscle tissue. Therefore these treatments are recommended for preservation of adequate muscle mass and function.

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Expression data of skeletal muscle from HRT users and non-users

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