RESUMEN

The loss of estrogen during menopause causes changes in the female body, with wide-ranging effects on health. Estrogen-containing hormone replacement therapy (HRT) leads to a relief of typical menopausal symptoms, benefits bone and muscle health, and is associated with tissue-specific gene expression profiles. As gene expression is controlled by epigenetic factors (including DNA methylation), many of which are environmentally sensitive, it is plausible that at least part of the HRT-associated gene expression is due to changes in DNA methylation profile. We investigated genome-wide DNA methylation and gene expression patterns of white blood cells (WBCs) and their associations with body composition, including muscle and bone measures of monozygotic (MZ) female twin pairs discordant for HRT. We identified 7,855 nominally significant differentially methylated regions (DMRs) associated with 4,044 genes. Of the genes with DMRs, five (ACBA1, CCL5, FASLG, PPP2R2B, and UHRF1) were also differentially expressed. All have been previously associated with HRT or estrogenic regulation, but not with HRT-associated DNA methylation. All five genes were associated with bone mineral content (BMC), and ABCA1, FASLG, and UHRF1 were also associated with body adiposity. Our study is the first to show that HRT associates with genome-wide DNA methylation alterations in WBCs. Moreover, we show that five differentially expressed genes with DMRs associate with clinical measures, including body fat percentage, lean body mass, bone mass, and blood lipids. Our results indicate that at least part of the known beneficial HRT effects on body composition and bone mass may be regulated by DNA methylation associated alterations in gene expression in circulating WBCs.

Asunto(s)

Adiposidad/genética , Índice de Masa Corporal , Densidad Ósea , Metilación de ADN , Expresión Génica , Terapia de Reemplazo de Hormonas , Leucocitos , Posmenopausia/genética , Femenino , Estudio de Asociación del Genoma Completo , Humanos

RESUMEN

AIM: This study aimed to determine whether Cannabinoid receptor 1 (CB1) is involved in mammalian target of rapamycin (mTOR) signaling and skeletal muscle protein synthesis. METHODS: This study used human vastus lateralis skeletal muscle biopsies obtained before and after a resistance exercise (RE) bout in young men (n=18). The signaling mechanisms were studied in vitro in human myotubes. Protein expression was determined by Western blot and confocal microscopy, and gene expression by quantitative PCR. Protein synthesis was measured in vitro using puromycin-based SuNSET technique. RESULTS: In human skeletal muscle, an anabolic stimulus in the form of RE down-regulated CB1 expression. The negative change in CB1 expression was associated with increased phosphorylation of mTOR signaling proteins. In vitro, CB1 antagonist AM251 induced phosphorylation of mTOR downstream targets, ribosomal protein S6 kinase (S6K1), S6 and eukaryotic initiation factor 4E binding protein (4E-BP1) in human myotubes. These effects were ERK1/2-dependent and insensitive to mTOR inhibitor, rapamycin. Compared to AM251 treatment alone, inhibition of ERK1/2 by UO126 in the presence of AM251 decreased phosphorylation of S6K1, S6 and and 4E-BP1 at Thr(37/46). AM251 increased protein synthesis in cultured human myotubes, which was not rapamycin-sensitive but was ERK1/2-dependent. CONCLUSIONS: Our results indicate that RE down-regulates CB1 expression. Inhibition of CB1 signaling increases skeletal muscle anabolic signaling down-stream of mTOR and protein synthesis through ERK1/2. Our study may provide base for the development of CB1-blocking drugs to treat or prevent muscle wasting.

Asunto(s)

Músculo Esquelético/fisiología , Receptor Cannabinoide CB1/metabolismo , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas de Ciclo Celular , Línea Celular , Expresión Génica , Humanos , Sistema de Señalización de MAP Quinasas , Masculino , Fibras Musculares Esqueléticas/metabolismo , Fosfoproteínas/metabolismo , Fosforilación , Piperidinas/farmacología , Biosíntesis de Proteínas , Procesamiento Proteico-Postraduccional , Pirazoles/farmacología , Receptor Cannabinoide CB1/antagonistas & inhibidores , Entrenamiento de Fuerza , Proteínas Quinasas S6 Ribosómicas 70-kDa/metabolismo , Adulto Joven

RESUMEN

Estrogen (E2 )-responsive peripheral tissues, such as skeletal muscle, may suffer from hormone deficiency after menopause potentially contributing to the aging of muscle. However, recently E2 was shown to be synthesized by muscle and its systemic and intramuscular hormone levels are unequal. The objective of the study was to examine the association between intramuscular steroid hormones and muscle characteristics in premenopausal women (n = 8) and in postmenopausal monozygotic twin sister pairs (n = 16 co-twins from eight pairs) discordant for the use of E2 -based hormone replacement. Isometric skeletal muscle strength was assessed by measuring knee extension strength. Explosive lower body muscle power was assessed as vertical jump height. Due to sequential nature of enzymatic conversion of biologically inactive dehydroepiandrosterone (DHEA) to testosterone (T) and subsequently to E2 or dihydrotestosterone (DHT), separate linear regression models were used to estimate the association of each hormone with muscle characteristics. Intramuscular E2 , T, DHT, and DHEA proved to be significant, independent predictors of strength and power explaining 59-64% of the variation in knee extension strength and 80-83% of the variation of vertical jumping height in women (P < 0.005 for all models). The models were adjusted for age, systemic E2 , and total body fat mass. The statistics used took into account the lack of statistical independence of twin sisters. Furthermore, muscle cells were shown to take up and actively synthesize hormones. Present study suggests intramuscular sex steroids to associate with strength and power regulation in female muscle providing novel insight to the field of muscle aging.

Asunto(s)

Hormonas Esteroides Gonadales/fisiología , Músculo Esquelético/fisiología , Adulto , Factores de Edad , Envejecimiento/fisiología , Estudios de Casos y Controles , Estudios Transversales , Terapia de Reemplazo de Estrógeno , Femenino , Humanos , Recién Nacido , Persona de Mediana Edad , Posmenopausia/fisiología , Premenopausia/fisiología , Factores Sexuales

RESUMEN

OBJECTIVE: This study aimed at establishing bacterial flagellin-recognizing toll-like receptor 5 (TLR5) as a novel link between gut microbiota composition, adipose tissue inflammation, and obesity. METHODS: An adipose tissue microarray database was used to compare women having the highest (n = 4, H-TLR) and lowest (n = 4, L-TLR) expression levels of TLR5-signaling pathway genes. Gut microbiota composition was profiled using flow cytometry and FISH. Standard laboratory techniques were used to determine anthropometric and clinical variables. In vivo results were verified using cultured human adipocytes. RESULTS: The H-TLR group had higher flagellated Clostridium cluster XIV abundance and Firmicutes-to-Bacteroides ratio. H-TLR subjects had obese phenotype characterized by greater waist circumference, fat %, and blood pressure (P < 0.05 for all). They also had higher leptin and lower adiponectin levels (P < 0.05 for both). Six hundred and sixty-eight metabolism- and inflammation-related adipose tissue genes were differentially expressed between the groups. In vitro studies confirmed that flagellin activated TLR5 inflammatory pathways, decreased insulin signaling, and increased glycerol secretion. CONCLUSIONS: The in vivo findings suggest that flagellated Clostridium cluster XIV bacteria contribute to the development of obesity through distorted adipose tissue metabolism and inflammation. The in vitro studies in adipocytes show that the underlying mechanisms of the human findings may be due to flagellin-activated TLR5 signaling.

Asunto(s)

Intestinos/microbiología , Microbiota/fisiología , Obesidad/genética , Paniculitis/genética , Paniculitis/microbiología , Receptor Toll-Like 5/fisiología , Tejido Adiposo/metabolismo , Tejido Adiposo/patología , Adolescente , Adulto , Células Cultivadas , Niño , Preescolar , Clostridium/fisiología , Femenino , Humanos , Inflamación/metabolismo , Persona de Mediana Edad , Obesidad/metabolismo , Obesidad/microbiología , Paniculitis/inmunología , Paniculitis/patología , Fenotipo , Transducción de Señal , Adulto Joven

RESUMEN

Biological aging is associated with physiological deteriorations, which are partly due to changes in the hormonal profile. MicroRNAs regulate various processes associated with cell senescence; differentiation, replication and apoptosis. Serum microRNAs have potential to serve as noninvasive markers for diagnostics/prognostics and therapeutic targets. We analysed the association of estrogen-based hormone replacement therapy (HRT) with selected microRNAs and inflammation markers from the serum, leukocytes and muscle biopsy samples from 54 to 62 year-old postmenopausal monozygotic twins (n=11 pairs) discordant for HRT usage. Premenopausal 30-35 year-old women (n=8) were used as young controls. We focused on the hormonal aging and on the interaction between HRT use and the modulation of miR-21, miR-146a and classical inflammation markers. Fas-ligand was analysed since it functions in both apoptosis and inflammation. The inflammatory profile was healthier among the premenopausal women compared to the postmenopausal twins. Serum miR-21 and miR-146a levels and FasL concentrations were lower in HRT users compared to their non-using co-twins, demonstrating their responsiveness to HRT. Based on the pairwise FasL analysis, FasL concentration is likely to be genetically controlled. Overall, we suggest that postmenopausal estrogen deficiency sustains the development of "inflamm-aging". Estrogen sensitive, specific circulating microRNAs could be potential, early biomarkers for age-associated physiological deteriorations.

Asunto(s)

Envejecimiento , Senescencia Celular , Estrógenos/administración & dosificación , Proteína Ligando Fas/sangre , MicroARNs , Posmenopausia , Adulto , Envejecimiento/genética , Envejecimiento/fisiología , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , Biomarcadores , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/fisiología , Senescencia Celular/genética , Senescencia Celular/fisiología , Terapia de Reemplazo de Estrógeno/métodos , Femenino , Humanos , Inflamación/sangre , MicroARNs/sangre , MicroARNs/genética , Persona de Mediana Edad , Músculo Esquelético/patología , Posmenopausia/sangre , Posmenopausia/genética , Posmenopausia/fisiología , Gemelos Monocigóticos

RESUMEN

MiRNAs are fine-tuning modifiers of skeletal muscle regulation, but knowledge of their hormonal control is lacking. We used a co-twin case-control study design, that is, monozygotic postmenopausal twin pairs discordant for estrogen-based hormone replacement therapy (HRT) to explore estrogen-dependent skeletal muscle regulation via miRNAs. MiRNA profiles were determined from vastus lateralis muscle of nine healthy 54-62-years-old monozygotic female twin pairs discordant for HRT (median 7 years). MCF-7 cells, human myoblast cultures and mouse muscle experiments were used to confirm estrogen's causal role on the expression of specific miRNAs, their target mRNAs and proteins and finally the activation of related signaling pathway. Of the 230 miRNAs expressed at detectable levels in muscle samples, qPCR confirmed significantly lower miR-182, miR-223 and miR-142-3p expressions in HRT using than in their nonusing co-twins. Insulin/IGF-1 signaling emerged one common pathway targeted by these miRNAs. IGF-1R and FOXO3A mRNA and protein were more abundantly expressed in muscle samples of HRT users than nonusers. In vitro assays confirmed effective targeting of miR-182 and miR-223 on IGF-1R and FOXO3A mRNA as well as a dose-dependent miR-182 and miR-223 down-regulations concomitantly with up-regulation of FOXO3A and IGF-1R expression. Novel finding is the postmenopausal HRT-reduced miRs-182, miR-223 and miR-142-3p expression in female skeletal muscle. The observed miRNA-mediated enhancement of the target genes' IGF-1R and FOXO3A expression as well as the activation of insulin/IGF-1 pathway signaling via phosphorylation of AKT and mTOR is an important mechanism for positive estrogen impact on skeletal muscle of postmenopausal women.

Asunto(s)

Terapia de Reemplazo de Hormonas/métodos , Factor I del Crecimiento Similar a la Insulina/metabolismo , MicroARNs/biosíntesis , Músculo Esquelético/metabolismo , Posmenopausia/metabolismo , Gemelos Monocigóticos , Factores de Edad , Anciano , Animales , Estudios de Casos y Controles , Femenino , Humanos , Células MCF-7 , Masculino , Ratones , MicroARNs/antagonistas & inhibidores , Persona de Mediana Edad , Posmenopausia/efectos de los fármacos , Posmenopausia/genética , Transducción de Señal

RESUMEN

Protein glycosylation via O-linked N-acetylglucosaminylation (O-GlcNAcylation) is an important post-translational regulatory mechanism mediated by O-GlcNAc transferase (OGT) and responsive to nutrients and stress. OGT attaches an O-GlcNAc moiety to proteins, while O-GlcNAcase (OGA) catalyzes O-GlcNAc removal. In skeletal muscle of experimental animals, prolonged increase in O-GlcNAcylation associates with age and muscle atrophy. Here we examined the effects of hormone replacement therapy (HRT) and power training (PT) on muscle OGT and OGA gene expression in postmenopausal women generally prone to age-related muscle weakness. In addition, the associations of OGT and OGA gene expressions with muscle phenotype were analyzed. Twenty-seven 50-57-year-old women participated in a yearlong randomized placebo-controlled trial: HRT (n=10), PT (n=8) and control (n=9). OGT and OGA mRNA levels were measured from muscle samples obtained at baseline and after one year. Knee extensor muscle cross-sectional area (CSA), knee extension force, running speed and vertical jumping height were measured. During the yearlong intervention, HRT suppressed the aging-associated upregulation of OGT mRNA that occurred in the controls. The effects of PT were similar but weaker. HRT also tended to increase the OGA mRNA level compared to the controls. The change in the ratio of OGT to OGA gene expressions correlated negatively with the change in muscle CSA. Our results suggest that OGT and OGA gene expressions are associated with muscle size during the critical postmenopausal period. HRT and PT influence muscle OGT and OGA gene expression, which may be one of the mechanisms by which HRT and PT prevent aging-related loss of muscle mass.

Asunto(s)

Terapia de Reemplazo de Estrógeno , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/enzimología , N-Acetilglucosaminiltransferasas/metabolismo , Ejercicio Pliométrico , Posmenopausia/metabolismo , beta-N-Acetilhexosaminidasas/metabolismo , Factores de Edad , Femenino , Finlandia , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Glicosilación , Humanos , Persona de Mediana Edad , Contracción Muscular , Fuerza Muscular , Músculo Esquelético/anatomía & histología , N-Acetilglucosaminiltransferasas/genética , Fenotipo , Posmenopausia/genética , Procesamiento Proteico-Postraduccional/efectos de los fármacos , ARN Mensajero/metabolismo , Factores de Tiempo , Resultado del Tratamiento , beta-N-Acetilhexosaminidasas/genética

RESUMEN

Recently, contradictory findings have been reported concerning the function of irisin and its precursor gene, skeletal muscle FNDC5, in energy homeostasis, and the associated regulatory role of exercise and PGC-1α. We therefore evaluated whether muscle FNDC5 mRNA and serum irisin are exercise responsive and whether PGC-1α expression is associated with FNDC5 expression. The male subjects in the study performed single exercises: (1) 1 h low-intensity aerobic exercise (AE) (middle-aged, n = 17), (2) a heavy-intensity resistance exercise (RE) bout (young n = 10, older n = 11) (27 vs. 62 years), (3) long-term 21 weeks endurance exercise (EE) training alone (twice a week, middle-aged, n = 9), or (4) combined EE and RE training (both twice a week, middle-aged, n = 9). Skeletal muscle mRNA expression was analysed by quantitative PCR and serum irisin by ELISA. No significant changes were observed in skeletal muscle PGC-1α, FNDC5 and serum irisin after AE, EE training or combined EE + RE training. However, a single RE bout increased PGC-1α by 4-fold in young and by 2-fold in older men, while FNDC5 mRNA only increased in young men post-RE, by 1.4-fold. Changes in PGC-1α or serum irisin were not consistently accompanied by changes in FNDC5. In conclusion, for the most part, neither longer-term nor single exercise markedly increases skeletal muscle FNDC5 expression or serum irisin. Therefore their changes in response to exercise are probably random and not consistent excluding the confirmation of any definitive link between exercise and FNDC5 expression and irisin release in humans. Moreover, irisin and FNDC5 were not associated with glucose tolerance and being overweight, or with metabolic disturbances, respectively. Finally, factor(s) other than PGC-1α and transcription may regulate FNDC5 expression.

Asunto(s)

Fibronectinas/metabolismo , Músculo Esquelético/metabolismo , Resistencia Física , Entrenamiento de Fuerza , Transcripción Genética , Adulto , Factores de Edad , Anciano , Estudios de Casos y Controles , Fibronectinas/sangre , Fibronectinas/genética , Humanos , Masculino , Persona de Mediana Edad , Músculo Esquelético/fisiología , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , ARN Mensajero/genética , ARN Mensajero/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo

RESUMEN

Human ageing is accompanied with deterioration in endocrine functions the most notable and well characterized of which being the decrease in the production of sex hormones. Current research literature suggests that low sex hormone concentration may be among the key mechanism for sarcopenia and muscle weakness. Within the European large scale MYOAGE project, the role of sex hormones, estrogens and testosterone, in causing the aging-related loss of muscle mass and function was further investigated. Hormone replacement therapy (HRT) in women is shown to diminish age-associated muscle loss, loss in fast muscle function (power), and accumulation of fat in skeletal muscle. Further HRT raises the protein synthesis rate in skeletal muscle after resistance training, and has an anabolic effect upon connective tissue in both skeletal muscle and tendon, which influences matrix structure and mechanical properties. HRT influences gene expression in e.g. cytoskeletal and cell-matrix proteins, has a stimulating effect upon IGF-I, and a role in IL-6 and adipokine regulation. Despite low circulating steroid-hormone level, postmenopausal women have a high local concentration of steroidogenic enzymes in skeletal muscle.

Asunto(s)

Hormonas Esteroides Gonadales/fisiología , Debilidad Muscular/fisiopatología , Músculo Esquelético/fisiopatología , Envejecimiento/fisiología , Estrógenos/fisiología , Femenino , Terapia de Reemplazo de Hormonas , Humanos , Masculino , Debilidad Muscular/prevención & control , Testosterona/fisiología

RESUMEN

Ageing is associated with a decline in muscle mass and strength leading to increased physical dependency in old age. Postmenopausal women experience a greater decline than men of similar age in parallel with the decrease in female sex steroid hormone production. We recruited six monozygous female twin pairs (55-59 years old) where only one twin pair was on hormone replacement therapy (HRT use = 7.8 ± 4.3 years) to investigate the association of HRT with the cytoplasmic volume supported by individual myonuclei (myonuclear domain (MND) size,) together with specific force at the single fibre level. HRT use was associated with a significantly smaller (∼27%; P < 0.05) mean MND size in muscle fibres expressing the type I but not the IIa myosin heavy chain (MyHC) isoform. In comparison to non-users, higher specific force was recorded in HRT users both in muscle fibres expressing type I (∼27%; P < 0.05) and type IIa (∼23%; P < 0.05) MyHC isoforms. These differences were fibre-type dependent, i.e. the higher specific force in fast-twitch muscle fibres was primarily caused by higher force per cross-bridge while slow-twitch fibres relied on both a higher number and force per cross-bridge. HRT use had no effect on fibre cross-sectional area (CSA), velocity of unloaded shortening (V0) and relative proportion of MyHC isoforms. In conclusion, HRT appears to have significant positive effects on both regulation of muscle contraction and myonuclei organization in postmenopausal women.

Asunto(s)

Estradiol/farmacología , Terapia de Reemplazo de Hormonas , Fibras Musculares Esqueléticas/efectos de los fármacos , Progesterona/farmacología , Gemelos Monocigóticos , Anciano , Anciano de 80 o más Años , Composición Corporal , Núcleo Celular , Femenino , Humanos , Masculino , Persona de Mediana Edad , Contracción Muscular/efectos de los fármacos , Fibras Musculares Esqueléticas/citología , Fibras Musculares Esqueléticas/fisiología , Cadenas Pesadas de Miosina/metabolismo , Posmenopausia , Isoformas de Proteínas/metabolismo

RESUMEN

OBJECTIVE: The aim of this study was to evaluate the possibility of preventing the metabolic health consequences of postmenopausal hypogonadism with the use of long-term hormone therapy (HT). METHODS: We used a monozygotic co-twin control design including 10 twin pairs (aged 56-62 y) discordant for HT (duration of HT, 2-10 y). In addition, 14 premenopausal women (aged 29-35 y) who did not use HT were studied to evaluate the differences in metabolic health between the premenopausal and postmenopausal states. Body composition was determined, and waist-to-hip ratio was used as an estimate for fat distribution. Serum sex steroids, sex hormone-binding globulin, and serum lipid and glucose profiles were analyzed. The serum levels of adiponectin, monocyte chemotactic protein-1, and leptin, as well as their local transcript levels in adipose tissue, skeletal muscle, and leukocytes, were measured. RESULTS: Long-term HT was associated with a healthier amount and distribution of body fat. No difference was seen in serum lipid concentrations between HT users and their nonusing identical twin sisters, but fasting serum glucose and glycated hemoglobin levels were 5% and 3% lower in HT users than in nonusers, respectively. Among the adipokines analyzed, the most notable finding was a 15% lower level of monocyte chemotactic protein-1 in HT users, particularly with respect to its suggested mediator role between obesity and insulin resistance. CONCLUSIONS: Long-term HT is associated with healthier amount and distribution of body fat and better adipocytokine profile, with concomitant signs of improved insulin sensitivity.

Asunto(s)

Adipoquinas/sangre , Glucemia/análisis , Composición Corporal , Terapia de Reemplazo de Estrógeno , Posmenopausia/fisiología , Adipoquinas/genética , Tejido Adiposo/química , Adulto , Estudios de Casos y Controles , Quimiocina CCL2/sangre , Femenino , Hormonas Esteroides Gonadales/sangre , Humanos , Resistencia a la Insulina , Leucocitos/química , Lípidos/sangre , Persona de Mediana Edad , Músculo Esquelético/química , Premenopausia , ARN Mensajero/análisis , Globulina de Unión a Hormona Sexual/análisis , Gemelos Monocigóticos , Relación Cintura-Cadera

RESUMEN

A thorough understanding of the role of estrogens on aging-related muscle weakness is lacking. To clarify the molecular mechanisms underlying the effects of hormone replacement therapy (HRT) on skeletal muscle, we analyzed systemic protein and local mRNA levels of factors related to interleukin 6 (IL-6) and insulin-like growth factor 1 (IGF-1) pathways in 30- to 35-year-old (n = 14) women (without hormonal contraceptives) and in 54- to 62-year-old monozygotic female twin pairs discordant for HRT (n = 11 pairs, mean duration of HRT 7.3 ± 3.7 years). Biopsies were taken from vastus lateralis muscle and from abdominal adipose tissue. We found, first, that the systemic levels of IL-6 receptors sIL-6R and sgp130 are sensitive to both age and HRT concomitant with the changes in body composition. The serum levels of sgp130 and sIL-6R were 16% and 52% (p ≤ 0.001 for both variables) higher in postmenopausal women than in premenopausal women, and 10% and 9% lower (p = 0.033 and p < 0.001, respectively) in the HRT using than in their non using co-twins. After adjustment for body fat amount, the differences were no more significant. Second, the transcript analyses emphasize the impact of adipose tissue on systemic levels of IL-6, sgp130 and sIL6R, both at pre- and postmenopausal age. In muscle, the most notable changes were 28% lower gene expression of IGF-1 splice variant Ea (IGF-1Ea) and 40% lower expression of splice variant Ec (IGF-1Ec) in the postmenopausal non-users than in premenopausal women (p = 0.016 and 0.019, respectively), and 28% higher expression of IGF1-receptor in HRT users than in non-users (p = 0.060). The results tend to demonstrate that HRT has positive anti-catabolic effect on aging skeletal muscle.

Asunto(s)

Tejido Adiposo/metabolismo , Envejecimiento/genética , Terapia de Reemplazo de Estrógeno , Expresión Génica , Interleucina-6/genética , Músculo Esquelético/metabolismo , ARN/genética , Adulto , Femenino , Humanos , Interleucina-6/metabolismo , Leucocitos/metabolismo , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , ARN/biosíntesis , Receptor IGF Tipo 1/metabolismo

RESUMEN

INTRODUCTION: Postmenopausal monozygotic twin pairs discordant for hormone replacement therapy (HRT) provide an advantageous study design controlling for genetic background for elucidating the relationships between aging, sex hormone levels, muscle strength, contractile capacity, and fatigability. METHODS: Thirteen postmenopausal monozygotic twin pairs discordant for HRT were measured for maximal voluntary torque (MVC) and twitch characteristics using electrical stimulation before and after intermittent dynamic plantarflexor exercise until exhaustion. RESULTS: Peak twitch torque was 32% higher in HRT users than in their non-HRT, genetically identical sisters (P = 0.002), but MVC did not differ. There were no differences in the activation level or twitch time characteristics between the co-twins. Fatigue caused decreases in MVC (P = 0.001), twitch torque (P = 0.001), time to peak (P = 0.013), and half-relaxation time (P = 0.001) similarly in HRT users and non-HRT users. CONCLUSION: In early postmenopausal women, involuntary but not voluntary force-generating mechanisms of the plantarflexors are augmented by the use of HRT.

Asunto(s)

Terapia de Reemplazo de Estrógeno , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Gemelos Monocigóticos , Electromiografía/métodos , Estradiol/sangre , Estradiol/uso terapéutico , Terapia de Reemplazo de Estrógeno/métodos , Femenino , Humanos , Persona de Mediana Edad , Contracción Muscular/efectos de los fármacos , Fatiga Muscular/efectos de los fármacos , Fuerza Muscular/efectos de los fármacos , Fuerza Muscular/fisiología , Músculo Esquelético/efectos de los fármacos , Gemelos Monocigóticos/genética

RESUMEN

Aging is associated with gradual decline of skeletal muscle strength and mass often leading to diminished muscle quality. This phenomenon is known as sarcopenia and affects about 30% of the over 60-year-old population. Androgens act as anabolic agents regulating muscle mass and improving muscle performance. The role of female sex steroids as well as the ability of skeletal muscle tissue to locally produce sex steroids has been less extensively studied. We show that despite the extensive systemic deficit of sex steroid hormones in postmenopausal compared to premenopausal women, the hormone content of skeletal muscle does not follow the same trend. In contrast to the systemic levels, muscle tissue of post- and premenopausal women had similar concentrations of dehydroepiandrosterone and androstenedione, while the concentrations of estradiol and testosterone were significantly higher in muscle of the postmenopausal women. The presence of steroidogenetic enzymes in muscle tissue indicates that the elevated postmenopausal steroid levels in skeletal muscle are because of local steroidogenesis. The circulating sex steroids were associated with better muscle quality while the muscle concentrations reflected the amount of infiltrated fat within muscle tissue. We conclude that systemically delivered and peripherally produced sex steroids have distinct roles in the regulation of neuromuscular characteristics during aging.

Asunto(s)

Envejecimiento/fisiología , Hormonas Esteroides Gonadales/metabolismo , Músculo Esquelético/fisiología , Adulto , Anciano , Androstenodiona/metabolismo , Androstenodiona/farmacología , Antropometría , Estudios de Cohortes , Deshidroepiandrosterona/metabolismo , Deshidroepiandrosterona/farmacología , Femenino , Expresión Génica , Hormonas Esteroides Gonadales/farmacología , Humanos , Persona de Mediana Edad , Músculo Esquelético/anatomía & histología , Músculo Esquelético/efectos de los fármacos , Posmenopausia , Premenopausia

RESUMEN

Aging is accompanied by inexorable loss of muscle tissue. One of the underlying causes for this is the massive change in the hormonal milieu of the body. The role of a female sex steroid - estrogen - in these processes is frequently neglected, although the rapid decline in its production coincides with a steep deterioration in muscle performance. We recruited 54- to 62-year-old monozygotic female twin pairs discordant for postmenopausal hormone replacement therapy (HRT, n=11 pairs; HRT use 7.3 ± 3.7 years) from the Finnish Twin Cohort to investigate the association of long-term, estrogen-based HRT with skeletal muscle transcriptome. Pathway analysis of muscle transcript profiles revealed significant HRT-induced up-regulation of a biological process related to regulation of cell structure and down-regulation of processes concerning, for example, cell-matrix interactions, energy metabolism and utilization of nutrients (false discovery rate < 0.15). Lending clinical relevance to the findings, these processes explained a significant fraction of the differences observed in relative proportion of muscle within thigh and in muscle performance (R(2) =0.180-0.257, P=0.001-0.023). Although energy metabolism was affected through down-regulation of the transcripts related to succinate dehydrogenase complex in mitochondria, no differences were observed in mtDNA copy number or oxidative capacity per muscle cross section. In conclusion, long-term use of HRT was associated with subtle, but significant, differences in muscle transcript profiles. The better muscle composition and performance among the HRT users appeared to be orchestrated by improved regulatory actions on cytoskeleton, preservation of muscle quality via regulation of intramuscular extracellular matrix and a switch from glucose-oriented metabolism to utilization of fatty acids.

Asunto(s)

Terapia de Reemplazo de Estrógeno/métodos , Perfilación de la Expresión Génica , Músculo Esquelético/metabolismo , Gemelos Monocigóticos/genética , Estudios de Cohortes , Variaciones en el Número de Copia de ADN , ADN Mitocondrial/genética , Regulación hacia Abajo , Femenino , Humanos , Persona de Mediana Edad , Succinato Deshidrogenasa/genética

RESUMEN

High physical activity/aerobic fitness predicts low morbidity and mortality. Our aim was to identify the most up-regulated gene sets related to long-term physical activity vs. inactivity in skeletal muscle and adipose tissues and to obtain further information about their link with cardio-metabolic risk factors. We studied ten same-sex twin pairs (age range 50-74 years) who had been discordant for leisure-time physical activity for 30 years. The examinations included biopsies from m. vastus lateralis and abdominal subcutaneous adipose tissue. RNA was analyzed with the genome-wide Illumina Human WG-6 v3.0 Expression BeadChip. For pathway analysis we used Gene Set Enrichment Analysis utilizing active vs. inactive co-twin gene expression ratios. Our findings showed that among the physically active members of twin pairs, as compared to their inactive co-twins, gene expression in the muscle tissue samples was chronically up-regulated for the central pathways related to energy metabolism, including oxidative phosphorylation, lipid metabolism and supportive metabolic pathways. Up-regulation of these pathways was associated in particular with aerobic fitness and high HDL cholesterol levels. In fat tissue we found physical activity-associated increases in the expression of polyunsaturated fatty acid metabolism and branched-chain amino acid degradation gene sets both of which associated with decreased 'high-risk' ectopic body fat and plasma glucose levels. Consistent with other findings, plasma lipidomics analysis showed up-regulation of the triacylglycerols containing the polyunsaturated fatty acids. Our findings identified skeletal muscle and fat tissue pathways which are associated with the long-term physical activity and reduced cardio-metabolic disease risk, including increased aerobic fitness. In particular, improved skeletal muscle oxidative energy and lipid metabolism as well as changes in adipocyte function and redistribution of body fat are associated with reduced cardio-metabolic risk.

Asunto(s)

Tejido Adiposo/metabolismo , Regulación de la Expresión Génica , Cardiopatías/genética , Cardiopatías/metabolismo , Actividad Motora , Músculo Esquelético/metabolismo , Gemelos/genética , Anciano , HDL-Colesterol/metabolismo , Estudios de Cohortes , Metabolismo Energético , Femenino , Finlandia , Cardiopatías/epidemiología , Cardiopatías/fisiopatología , Humanos , Metabolismo de los Lípidos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Gemelos/metabolismo

RESUMEN

OBJECTIVES: To investigate the effects of combined hormone replacement therapy (HRT) and its effective agents on the IGF-1 signaling pathway. DESIGN AND METHODS: To examine the effects of HRT on skeletal muscle in vivo, we utilized pre- and post-intervention samples from a randomized double blinded trial with 50-57-year-old women. The intervention included the year-long use of either HRT preparation (2 mg 17ß-estradiol, E2; 1mg norethisterone acetate, NETA, n=10) or placebo (CO, n=9). Microarray technology and quantitative PCR (qPCR) were used to study the expression of insulin-like growth factor I (IGF-1) and its splice variants as well as IGF-1 receptor, Akt1, mTOR, FOXO1, FOXO3, atrogin, estrogen receptors and androgen receptor in muscle samples. Serum concentrations of IGF-1, E(2) and testosterone were measured. C2C12 myotubes were fed with E2 or NETA followed by analyzing the expression of essentially the same gene transcripts as in human samples by qPCR and phosphorylation of Akt and mTOR by Western blotting. RESULTS: The gene expression of IGF-1 and its splice variant, IGF-1Ec (also known as the mechano growth factor or MGF), mTOR, FOXO3, and AR was up-regulated among the HRT users compared to the CO (P<0.05), while Akt1 was down-regulated (P<0.05). The change in the level of IGF-1Ec transcript correlated positively with muscle size at post-intervention (r=0.5, P<0.05). In C2C12 myotubes, no statistically significant effects of either E2 or NETA at the level of gene transcripts studied were identified. The amount of phosphorylated Akt appeared to respond to NETA, albeit the response was not statistically significant. Phosphorylation of mTOR did not respond to either of the treatments. CONCLUSION: Year-long postmenopausal HRT was found to affect the expression of the genes along the IGF-1 signaling cascade reflecting the higher muscle mass compared to the CO women. By using cell culture model we were, however, unable to confirm the possible differential role of E2 and NETA. It appears that the synchronous presence of both effective agents of the HRT or the presence of yet unidentified microenvironmental factors providing proper paracrine signals naturally existing in the intact muscle tissue is critical for appropriate signaling via sex steroid-IGF-1 axis to occur.

Asunto(s)

Estradiol/uso terapéutico , Terapia de Reemplazo de Estrógeno , Factor I del Crecimiento Similar a la Insulina/biosíntesis , Músculo Esquelético/efectos de los fármacos , Noretindrona/análogos & derivados , Estradiol/sangre , Femenino , Proteína Forkhead Box O1 , Proteína Forkhead Box O3 , Factores de Transcripción Forkhead/biosíntesis , Factores de Transcripción Forkhead/genética , Humanos , Factor I del Crecimiento Similar a la Insulina/análisis , Factor I del Crecimiento Similar a la Insulina/genética , Persona de Mediana Edad , Fibras Musculares Esqueléticas/química , Fibras Musculares Esqueléticas/efectos de los fármacos , Proteínas Musculares/biosíntesis , Proteínas Musculares/genética , Músculo Esquelético/química , Noretindrona/uso terapéutico , Acetato de Noretindrona , Isoformas de Proteínas/biosíntesis , Isoformas de Proteínas/genética , Proteínas Proto-Oncogénicas c-akt/biosíntesis , Proteínas Proto-Oncogénicas c-akt/genética , Ensayos Clínicos Controlados Aleatorios como Asunto , Receptor IGF Tipo 1/biosíntesis , Receptor IGF Tipo 1/genética , Receptores Androgénicos/biosíntesis , Receptores Androgénicos/genética , Receptores de Estrógenos/biosíntesis , Receptores de Estrógenos/genética , Proteínas Ligasas SKP Cullina F-box/biosíntesis , Proteínas Ligasas SKP Cullina F-box/genética , Serina-Treonina Quinasas TOR/biosíntesis , Serina-Treonina Quinasas TOR/genética , Testosterona/sangre , Transcripción Genética/efectos de los fármacos

RESUMEN

At the moment, there is no clear molecular explanation for the steeper decline in muscle performance after menopause or the mechanisms of counteractive treatments. The goal of this genome-wide study was to identify the genes and gene clusters through which power training (PT) comprising jumping activities or estrogen containing hormone replacement therapy (HRT) may affect skeletal muscle properties after menopause. We used musculus vastus lateralis samples from early stage postmenopausal (50-57 years old) women participating in a yearlong randomized double-blind placebo-controlled trial with PT and HRT interventions. Using microarray platform with over 24,000 probes, we identified 665 differentially expressed genes. The hierarchical clustering method was used to assort the genes. Additionally, enrichment analysis of gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways was carried out to clarify whether assorted gene clusters are enriched with particular functional categories. The analysis revealed transcriptional regulation of 49 GO/KEGG categories. PT upregulated transcription in "response to contraction"-category revealing novel candidate genes for contraction-related regulation of muscle function while HRT upregulated gene expression related to functionality of mitochondria. Moreover, several functional categories tightly related to muscle energy metabolism, development, and function were affected regardless of the treatment. Our results emphasize that during the early stages of the postmenopause, muscle properties are under transcriptional modulation, which both PT and HRT partially counteract leading to preservation of muscle power and potentially reducing the risk for aging-related muscle weakness. More specifically, PT and HRT may function through improving energy metabolism, response to contraction as well as by preserving functionality of the mitochondria.

Asunto(s)

Terapia de Reemplazo de Estrógeno , Músculo Esquelético/metabolismo , Posmenopausia , Transcripción Genética/efectos de los fármacos , Ejercicio Físico , Femenino , Humanos , Persona de Mediana Edad , Músculo Esquelético/efectos de los fármacos

RESUMEN

According to the classical ABC model, B-function genes are involved in determining petal and stamen development. Most core eudicot species have B class genes belonging to three different lineages: the PI, euAP3, and TM6 lineages, although both Arabidopsis and Antirrhinum appear to have lost their TM6-like gene. Functional studies were performed for three gerbera (Gerbera hybrida) B class MADS-box genes--PI/GLO-like GGLO1, euAP3 class GDEF2, and TM6-like GDEF1--and data are shown for a second euAP3-like gene, GDEF3. In phylogenetic analysis, GDEF3 is a closely related paralogue of GDEF2, and apparently stems from a duplication common to all Asteraceae. Expression analysis and transgenic phenotypes confirm that GGLO1 and GDEF2 mediate the classical B-function since they determine petal and stamen identities. However, based on assays in yeast, three B class heterodimer combinations are possible in gerbera. In addition to the interaction of GGLO1 and GDEF2 proteins, GGLO1 also pairs with GDEF1 and GDEF3. This analysis of GDEF1 represents the first functional characterization of a TM6-like gene in a core eudicot species outside Solanaceae. Similarly to its relatives in petunia and tomato, the expression pattern and transgenic phenotypes indicate that GDEF1 is not involved in determination of petal identity, but has a redundant role in regulating stamen development.

Asunto(s)

Asteraceae/metabolismo , Proteínas de Dominio MADS/metabolismo , Asteraceae/genética , Regulación hacia Abajo/genética , Flores/genética , Flores/ultraestructura , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Genes de Plantas/genética , Proteínas de Dominio MADS/genética , Especificidad de Órganos , Fenotipo , Filogenia , Epidermis de la Planta/citología , Epidermis de la Planta/ultraestructura , Plantas Modificadas Genéticamente , Unión Proteica

RESUMEN

We investigated whether long-term hormone replacement therapy (HRT) is associated with mobility and lower limb muscle performance and composition in postmenopausal women. Fifteen 54- to 62-yr-old monozygotic female twin pairs discordant for HRT were recruited from the Finnish Twin Cohort. Habitual (HWS) and maximal (MWS) walking speeds over 10 m, thigh muscle composition, lower body muscle power assessed as vertical jumping height, and maximal isometric hand grip and knee extension strengths were measured. Intrapair differences (IPD%) with 95% confidence intervals (CI) were calculated. The mean duration of HRT use was 6.9 +/- 4.1 yr. MWS was on average 7% (0.9 to 13.1%, P = 0.019) and muscle power 16% (-0.8 to 32.8%, P = 0.023) greater in HRT users than in their cotwins. Thigh muscle cross-sectional area tended to be larger (IPD% = 6%, 95% CI: -0.07 to 12.1%, P = 0.065), relative muscle area greater (IPD% = 8%, CI: 0.8 to 15.0%, P = 0.047), and relative fat area smaller (IPD% = -5%, CI: -11.3 to 1.2%, P = 0.047) in HRT users than in their sisters. There were no significant differences in maximal isometric strengths or HWS between users and nonusers. Subgroup analyses revealed that estrogen-containing therapies (11 pairs) significantly decreased total body and thigh fat content, whereas tibolone (4 pairs) tended to increase muscle cross-sectional area. This study showed that long-term HRT was associated with better mobility, greater muscle power, and favorable body and muscle composition among 54- to 62-yr-old women. The results indicate that HRT is a potential agent in preventing muscle weakness and mobility limitation in older women.

Asunto(s)

Terapia de Reemplazo de Estrógeno , Estrógenos/farmacología , Menopausia/fisiología , Contracción Muscular/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Estrógenos/sangre , Femenino , Fuerza de la Mano/fisiología , Humanos , Contracción Isométrica/fisiología , Persona de Mediana Edad , Contracción Muscular/fisiología , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/fisiología , Tomografía Computarizada por Rayos X , Estudios en Gemelos como Asunto , Gemelos Monocigóticos , Caminata/fisiología