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1.
Nutrients ; 12(2)2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32023931

RESUMO

Cooking changes the texture and tenderness of red meat, which may influence its digestibility, circulatory amino acids (AA) and gastrointestinal (GI) hormonal responses in consumers. In a randomised crossover intervention, healthy males (n = 12) consumed a beef steak sandwich, in which the beef was cooked by either a pan-fried (PF) or sous-vide (SV) method. Plasma AA were measured by ultrahigh performance liquid chromatography (UPLC), while plasma GI hormones were measured using a flow cytometric multiplex array. Following meat ingestion, the circulatory concentrations of some of the essential AA (all the branched-chain AA: leucine, isoleucine and valine; and threonine), some of the nonessential AA (glycine, alanine, tyrosine and proline) and some of the nonproteogenic AA (taurine, citrulline and ornithine) were increased from fasting levels by 120 or 180 min (p < 0.05). There were no differences in circulating AA concentrations between cooking methods. Likewise, of the measured GI hormones, glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1) concentrations increased from fasting levels after consumption of the steak sandwich (p < 0.05), with no differences between the cooking methods. In the healthy male adults, protein digestion and circulating GI hormone responses to a beef-steak breakfast were unaltered by the different cooking methods.

2.
Nutrients ; 11(12)2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31795162

RESUMO

B-vitamin deficiency is common in ageing populations either due to altered dietary habits or altered digestive and metabolic functions. There is limited data on the acute circulating concentrations of B-vitamins and their various forms (vitamers), following ingestion of realistic meals. This study compared the acute circulating B-vitamin and vitamer responses to either an energy-dense (ED) or a nutrient-dense (ND) breakfast meal, consumed in a randomized cross-over sequence, in older and younger adults (n = 15 and 15, aged 67.3 ± 1.5 and 22.7 ± 0.5 years (mean ± SEM), respectively). Eleven differing B-vitamins and vitamers were determined in plasma samples by ultra-high-performance liquid chromatography-tandem mass spectrometry, in the fasting and postprandial state (hourly for 5 h). While postprandial thiamine concentration increased following both meals, riboflavin increased only following a ND meal in both age groups. Many vitamins including nicotinic acid, pantothenic acid, pyridoxal, pyridoxamine, pyridoxal-5'phosphate, and 4-pyridoxic acid remained unaltered, and flavin mononucleotide (FMN), nicotinamide and nicotinuric acid concentrations reduced following both meals. Biological age and food composition had minimal impact on postprandial B-vitamin concentrations, yet the differences between the ED and ND meals for riboflavin highlight the importance of riboflavin intake to achieve adequacy.

3.
Int J Sport Nutr Exerc Metab ; : 1-7, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31592623

RESUMO

PURPOSE: To determine the acute effects of carbohydrate (CHO) ingestion following a bout of maximal eccentric resistance exercise on key anabolic kinases of mammalian target of rapamycin and extracellular signal-regulated kinase (ERK) pathways. The authors' hypothesis was that the activation of anabolic signaling pathways known to be upregulated by resistance exercise would be further stimulated by the physiological hyperinsulinemia resulting from CHO supplementation. METHODS: Ten resistance-trained men were randomized in a crossover, double-blind, placebo (PLA)-controlled manner to ingest either a noncaloric PLA or 3 g/kg of CHO beverage throughout recovery from resistance exercise. Muscle biopsies were collected at rest, immediately after a single bout of intense lower body resistance exercise, and after 3 hr of recovery. RESULTS: CHO ingestion elevated plasma glucose and insulin concentrations throughout recovery compared with PLA ingestion. The ERK pathway (phosphorylation of ERK1/2 [Thr202/Tyr204], RSK [Ser380], and p70S6K [Thr421/Ser424]) was markedly activated immediately after resistance exercise, without any effect of CHO supplementation. The phosphorylation state of AKT (Thr308) was unchanged postexercise in the PLA trial and increased at 3 hr of recovery above resting with ingestion of CHO compared with PLA. Despite stimulating-marked phosphorylation of AKT, CHO ingestion did not enhance resistance exercise-induced phosphorylation of p70S6K (Thr389) and rpS6 (Ser235/236 and Ser240/244). CONCLUSION: CHO supplementation after resistance exercise and hyperinsulinemia does not influence the ERK pathway nor the mTORC1 target p70S6K and its downstream proteins, despite the increased AKT phosphorylation.

4.
Physiol Rep ; 7(13): e14108, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31257737

RESUMO

Lipid mediators including classical arachidonic acid-derived eicosanoids (e.g. prostaglandins and leukotrienes) and more recently identified specialized pro-resolving-mediator metabolites of the omega-3 fatty acids play essential roles in initiation, self-limitation, and active resolution of acute inflammatory responses. In this study, we examined the bioactive lipid mediator profile of human skeletal muscle at rest and following acute resistance exercise. Twelve male subjects completed a single bout of maximal isokinetic unilateral knee extension exercise and muscle biopsies were taken from the m.vastus lateralis before and at 2, 4, and 24 h of recovery. Muscle tissue lipid mediator profile was analyzed via liquid chromatography-mass spectrometry (LC-MS)-based targeted lipidomics. At 2 h postexercise, there was an increased intramuscular abundance of cyclooxygenase (COX)-derived thromboxanes (TXB2 : 3.33 fold) and prostaglandins (PGE2 : 2.52 fold and PGF2α : 1.77 fold). Resistance exercise also transiently increased muscle concentrations of lipoxygenase (LOX) pathway-derived leukotrienes (12-Oxo LTB4 : 1.49 fold and 20-COOH LTB4 : 2.91 fold), monohydroxy-eicosatetraenoic acids (5-HETE: 2.66 fold, 12-HETE: 2.83 fold, and 15-HETE: 1.69 fold) and monohydroxy-docosahexaenoic acids (4-HDoHE: 1.69 fold, 7-HDoHE: 1.58 fold and 14-HDoHE: 2.35 fold). Furthermore, the abundance of CYP pathway-derived epoxy- and dihydroxy-eicosatrienoic acids was increased in 2 h postexercise biopsies (5,6-EpETrE: 2.48 fold, 11,12-DiHETrE: 1.66 fold and 14,15-DiHETrE: 2.23 fold). These data reveal a range of bioactive lipid mediators as present within human skeletal muscle tissue and demonstrate that acute resistance exercise transiently stimulates the local production of both proinflammatory eicosanoids and pathway markers in specialized proresolving mediator biosynthesis circuits.

5.
Front Nutr ; 6: 91, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31249834

RESUMO

Progressive muscle loss with aging results in decreased physical function, frailty, and impaired metabolic health. Deficits in anabolic signaling contribute to an impaired ability for aged skeletal muscle to adapt in response to exercise and protein feeding. One potential contributing mechanism could be exerted by dysregulation of microRNAs (miRNAs). Therefore, the aim of this study was to determine if graded protein doses consumed after resistance exercise altered muscle miRNA expression in elderly men. Twenty-three senior men (67.9 ± 0.9 years) performed a bout of resistance exercise and were randomized to consume either a placebo, 20 or 40 g of whey protein (n = 8, n = 7, and n = 8, respectively). Vastus lateralis biopsies were collected before, 2 and 4 h after exercise. Expression of 19 miRNAs, previously identified to influence muscle phenotype, were measured via RT-PCR. Of these, miR-16-5p was altered with exercise in all groups (p = 0.032). Expression of miR-15a and-499a increased only in the placebo group 4 h after exercise and miR-451a expression increased following exercise only in the 40 g whey supplementation group. Changes in p-P70S6KThr389 and p-AktSer473 following exercise were correlated with alterations in miR-208a and-499a and-206 expression, irrespective of protein dose, suggesting a possible role for miRNA in the regulation of acute phosphorylation events during early hours of exercise recovery.

6.
Eur J Nutr ; 58(3): 1047-1054, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29445912

RESUMO

PURPOSE: Elemental deficiencies are highly prevalent and have a significant impact on health. However, clinical monitoring of plasma elemental responses to foods remains largely unexplored. Data from in vitro studies show that red meat (beef) is a highly bioavailable source of several key elements, but cooking method may influence this bioavailability. We therefore studied the postprandial responses to beef steak, and the effects of two different cooking methods, in healthy young males. METHODS: In a randomized cross-over controlled trial, healthy males (n = 12, 18-25 years) were fed a breakfast of beef steak (270 ± 20 g) in which the meat was either pan-fried (PF) or sous-vide (SV) cooked. Baseline and postprandial blood samples were collected and the plasma concentrations of 15 elements measured by inductively coupled plasma-mass spectrometry (ICP-MS). RESULTS: Concentrations of Fe and Zn changed after meal ingestion, with plasma Fe increasing (p < 0.001) and plasma Zn decreasing (p < 0.05) in response to both cooking methods. The only potential treatment effect was seen for Zn, where the postprandial area under the curve was lower in response to the SV meal (2965 ± 357) compared to the PF meal (3190 ± 310; p < 0.05). CONCLUSIONS: This multi-element approach demonstrated postprandial responsiveness to a steak meal, and an effect of the cooking method used. This suggests the method would provide insight in future elemental metabolic studies to evaluate responses to meat-based meals, including longer-term interventions in more specifically defined cohorts to clearly establish the role of red meat as an important source of elements.


Assuntos
Culinária/métodos , Temperatura Alta , Ferro na Dieta/sangue , Carne Vermelha , Zinco/sangue , Adolescente , Adulto , Disponibilidade Biológica , Estudos Cross-Over , Humanos , Masculino , Período Pós-Prandial , Valores de Referência , Adulto Jovem
7.
Free Radic Biol Med ; 124: 241-248, 2018 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-29909291

RESUMO

Extended periods of skeletal muscle disuse result in muscle atrophy. Following limb immobilization, increased mitochondrial reactive oxygen species (ROS) production may contribute to atrophy through increases in skeletal muscle protein degradation. However, the effect of skeletal muscle disuse on mitochondrial ROS production remains unclear. This study investigated the effect of immobilization, followed by two subsequent periods of restored physical activity, on mitochondrial H2O2 emissions in adult male skeletal muscle. Middle-aged men (n = 30, 49.7 ±â€¯3.84 y) completed two weeks of unilateral lower-limb immobilization, followed by two weeks of baseline-matched activity, consisting of 10,000 steps a day, then completed two weeks of three times weekly supervised resistance training. Vastus lateralis biopsies were taken at baseline, post-immobilization, post-ambulatory recovery, and post-resistance-training. High-resolution respirometry was used simultaneously with fluorometry to determine mitochondrial respiration and hydrogen peroxide (H2O2) production in permeabilized muscle fibres. Mitochondrial H2O2 emission with complex I and II substrates, in the absence of ADP, was greater following immobilization, however, there was no effect on mitochondrial respiration. Both ambulatory recovery and resistance training, following the period of immobilization, increased in mitochondrial H2O2 emissions. These data demonstrated that 2 weeks of immobilization increases mitochondrial H2O2 emissions, but subsequent retraining periods of ambulatory recovery and resistance training also led to in robust increases in mitochondrial H2O2 emissions in skeletal muscle.


Assuntos
Exercício/fisiologia , Peróxido de Hidrogênio/metabolismo , Mitocôndrias/metabolismo , Músculo Esquelético/metabolismo , Restrição Física/fisiologia , Respiração Celular/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Treinamento de Resistência
8.
J Appl Physiol (1985) ; 125(2): 271-286, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29698111

RESUMO

Strenuous exercise can result in skeletal muscle damage, leading to the systemic mobilization, activation, and intramuscular accumulation of blood leukocytes. Eicosanoid metabolites of arachidonic acid (ARA) are potent inflammatory mediators, but whether changes in dietary ARA intake influence exercise-induced inflammation is not known. This study investigated the effect of 4 wk of dietary supplementation with 1.5 g/day ARA ( n = 9, 24 ± 1.5 yr) or corn-soy oil placebo ( n = 10, 26 ± 1.3 yr) on systemic and intramuscular inflammatory responses to an acute bout of resistance exercise (8 sets each of leg press and extension at 80% one-repetition maximum) in previously trained men. Whole EDTA blood, serum, peripheral blood mononuclear cells (PMBCs), and skeletal muscle biopsies were collected before exercise, immediately postexercise, and at 2, 4, and 48 h of recovery. ARA supplementation resulted in higher exercise-stimulated serum creatine kinase activity [incremental area under the curve (iAUC) P = 0.046] and blood leukocyte counts (iAUC for total white cells, P < 0.001; neutrophils: P = 0.007; monocytes: P = 0.015). The exercise-induced fold change in peripheral blood mononuclear cell mRNA expression of interleukin-1ß ( IL1B), CD11b ( ITGAM), and neutrophil elastase ( ELANE), as well as muscle mRNA expression of the chemokines interleukin-8 ( CXCL8) and monocyte chemoattractant protein 1 ( CCL2) was also greater in the ARA group than placebo. Despite this, ARA supplementation did not influence the histological presence of leukocytes within muscle, perceived muscle soreness, or the extent and duration of muscle force loss. These data show that ARA supplementation transiently increased the inflammatory response to acute resistance exercise but did not impair recovery. NEW & NOTEWORTHY Daily arachidonic acid supplementation for 4 wk in trained men augmented the acute systemic and intramuscular inflammatory response to a subsequent bout of resistance exercise. Greater exercise-induced inflammatory responses in men receiving arachidonic acid supplementation were not accompanied by increased symptoms of exercise-induced muscle damage. Although increased dietary arachidonic acid intake does not appear to influence basal inflammation in humans, the acute inflammatory response to exercise stress is transiently increased following arachidonic acid supplementation.


Assuntos
Ácido Araquidônico/administração & dosagem , Exercício/fisiologia , Inflamação/tratamento farmacológico , Treinamento de Resistência/efeitos adversos , Adolescente , Adulto , Antígeno CD11b/metabolismo , Quimiocina CCL2/metabolismo , Creatina Quinase/metabolismo , Suplementos Nutricionais , Humanos , Inflamação/metabolismo , Interleucina-1beta/metabolismo , Interleucina-8/metabolismo , Elastase de Leucócito/metabolismo , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/metabolismo , Masculino , Força Muscular/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Mialgia/tratamento farmacológico , Mialgia/metabolismo , RNA Mensageiro/metabolismo , Adulto Jovem
9.
J Appl Physiol (1985) ; 124(4): 1080-1091, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29389245

RESUMO

Arachidonic acid (ARA), a polyunsaturated ω-6 fatty acid, acts as precursor to a number of prostaglandins with potential roles in muscle anabolism. It was hypothesized that ARA supplementation might enhance the early anabolic response to resistance exercise (RE) by increasing muscle protein synthesis (MPS) via mammalian target of rapamycin (mTOR) pathway activation and/or the late anabolic response by modulating ribosome biogenesis and satellite cell expansion. Nineteen men with ≥1 yr of resistance-training experience were randomized to consume either 1.5 g daily ARA or a corn-soy-oil placebo in a double-blind manner for 4 wk. Participants then undertook fasted RE (8 sets each of leg press and extension at 80% 1-repetition maximum), with vastus lateralis biopsies obtained before exercise, immediately postexercise, and at 2, 4, and 48 h of recovery. MPS (measured via stable isotope infusion) was not different between groups ( P = 0.212) over the 4-h recovery period. mTOR pathway members p70 S6 kinase and S6 ribosomal protein were phosphorylated postexercise ( P < 0.05), with no difference between groups. 45S preribosomal RNA increased 48 h after exercise only in ARA ( P = 0.012). Neural cell adhesion molecule-positive satellite cells per fiber increased 48 h after exercise ( P = 0.013), with no difference between groups ( P = 0.331). Prior ARA supplementation did not alter the acute anabolic response to RE in previously resistance-trained men; however, at 48 h of recovery, ribosome biogenesis was stimulated only in the ARA group. The findings do not support a mechanistic link between ARA and short-term anabolism, but ARA supplementation in conjunction with resistance training may stimulate increases in translational capacity. NEW & NOTEWORTHY Four weeks of daily arachidonic acid supplementation in trained men did not alter their acute muscle protein synthetic or anabolic signaling response to resistance exercise. However, 48 h after exercise, men supplemented with arachidonic acid showed greater ribosome biogenesis and a trend toward greater change in satellite cell content. Chronic arachidonic acid supplementation does not appear to regulate the acute anabolic response to resistance exercise but may augment muscle adaptation in the following days of recovery.


Assuntos
Ácido Araquidônico/administração & dosagem , Proteínas Musculares/biossíntese , Músculo Esquelético/efeitos dos fármacos , Treinamento de Resistência , Adulto , Suplementos Nutricionais , Humanos , Sistema de Sinalização das MAP Quinases , Masculino , Ribossomos/metabolismo , Células Satélites de Músculo Esquelético , Adulto Jovem
10.
Artigo em Inglês | MEDLINE | ID: mdl-29413364

RESUMO

Arachidonic acid (ARA), an omega-6 polyunsaturated fatty acid (PUFA), is the metabolic precursor to the eicosanoid family of lipid mediators. Eicosanoids have potent pro-inflammatory actions, but also act as important autocrine/paracrine signaling molecules in skeletal muscle growth and development. Whether dietary ARA is incorporated into skeletal muscle phospholipids and the resulting impact on intramuscular inflammatory and adaptive processes in-vivo is not known. In the current study, resistance trained men (≥1 year) received dietary supplementation with 1.5g/day ARA (n=9, 24 ± 1.5 years) or placebo (n=10, 26 ± 1.3 years) for 4-weeks while continuing their normal training regimen. Plasma and vastus lateralis muscle biopsies were collected in an overnight fasted state at baseline and week 4. ARA supplementation increased plasma content of ARA and gamma-linolenic acid, while decreasing relative abundance of linoleic acid, eicosapentaenoic acid, and dihomo-gamma-linolenic acid. In skeletal muscle, ARA and dihomo-gamma-linolenic acid content increased, whereas alpha-linolenic-acid was reduced. Compared to placebo, ARA supplementation reduced circulating platelet and monocyte number, and decreased the mRNA expression of the immune cell surface markers; neutrophil elastase/CD66b and interleukin 1-beta, in peripheral blood mononuclear cells. In muscle, ARA supplementation increased mRNA expression of the myogenic regulatory factors; MyoD and myogenin, but had no effect on a range of immune cell markers or inflammatory cytokines. These data show that dietary ARA supplementation can rapidly and safely modulate plasma and muscle fatty acid profile and promote myogenic gene expression in resistance trained men, without a risk of increasing basal systemic or intramuscular inflammation.


Assuntos
Ácido Araquidônico/farmacologia , Inflamação/dietoterapia , Lipídeos/análise , Músculo Esquelético/efeitos dos fármacos , Adolescente , Adulto , Ácido Araquidônico/administração & dosagem , Análise Química do Sangue , Composição Corporal/efeitos dos fármacos , Suplementos Nutricionais , Ácidos Graxos/análise , Ácidos Graxos/sangue , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Leucócitos Mononucleares/efeitos dos fármacos , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipídeos/sangue , Masculino , Músculo Esquelético/metabolismo
12.
Am J Physiol Regul Integr Comp Physiol ; 314(6): R824-R833, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29466686

RESUMO

Resistance training (RT) increases muscle fiber size and induces angiogenesis to maintain capillary density. Cold water immersion (CWI), a common postexercise recovery modality, may improve acute recovery, but it attenuates muscle hypertrophy compared with active recovery (ACT). It is unknown if CWI following RT alters muscle fiber type expression or angiogenesis. Twenty-one men strength trained for 12 wk, with either 10 min of CWI ( n = 11) or ACT ( n = 10) performed following each session. Vastus lateralis biopsies were collected at rest before and after training. Type IIx myofiber percent decreased ( P = 0.013) and type IIa myofiber percent increased with training ( P = 0.012), with no difference between groups. The number of capillaries per fiber increased from pretraining in the CWI group ( P = 0.004) but not the ACT group ( P = 0.955). Expression of myosin heavy chain genes ( MYH1 and MYH2), encoding type IIx and IIa fibers, respectively, decreased in the ACT group, whereas MYH7 (encoding type I fibers) increased in the ACT group versus CWI ( P = 0.004). Myosin heavy chain IIa protein increased with training ( P = 0.012) with no difference between groups. The proangiogenic vascular endothelial growth factor protein decreased posttraining in the ACT group versus CWI ( P < 0.001), whereas antiangiogenic Sprouty-related, EVH1 domain-containing protein 1 protein increased with training in both groups ( P = 0.015). Expression of microRNAs that regulate muscle fiber type (miR-208b and -499a) and angiogenesis (miR-15a, -16, and -126) increased only in the ACT group ( P < 0.05). CWI recovery after each training session altered the angiogenic and fiber type-specific response to RT through regulation at the levels of microRNA, gene, and protein expression.


Assuntos
Temperatura Baixa , Imersão , Fibras Musculares Esqueléticas/fisiologia , Neovascularização Fisiológica/fisiologia , Treinamento de Resistência , Capilares/fisiologia , Miosinas Cardíacas/biossíntese , Humanos , Masculino , MicroRNAs/biossíntese , Força Muscular/fisiologia , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/citologia , Cadeias Pesadas de Miosina/biossíntese , Fluxo Sanguíneo Regional/fisiologia , Fator A de Crescimento do Endotélio Vascular/biossíntese , Adulto Jovem
13.
Mol Nutr Food Res ; 62(7): e1701028, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29377592

RESUMO

Limb immobilization results in a rapid loss of muscle size and strength. The resultant alterations in signaling pathways governing myogenesis, catabolism, and mitochondrial biogenesis are likely to include posttranscriptional regulation mediated by altered microRNAs (miRNAs). Given that protein ingestion exerts an anabolic action and may act as a countermeasure to mitigate muscle loss with immobilization, it is important to examine miRNA in this context. The objective of the study is therefore to characterize the vastus lateralis miRNA response to 14 days of disuse in males (45-60 years) randomized to receive supplementation with 20 g d-1 of dairy protein (n = 12) or isocaloric carbohydrate placebo (n = 13). Biopsies are collected before and after a 2-week immobilization period. Of the 24 miRNAs previously identified in myogenic regulation, seven (miR-133a, -206, -15a, -451a, -126, -208b, and let-7e) are increased with immobilization irrespective of group; five (miR-16, -494, let-7a, -7c, and 7d) increased only in the carbohydrate group; and eight (miR-1, -486, -23a, -23b, -26a, -148b, let-7b, and -7g) are divergently expressed between groups (suppressed with protein). The ability of protein supplementation to differentially regulate miRNAs involved in key muscle regulatory pathways following short-term limb immobilization reflects potential protective function in mitigating muscle loss during limb immobilization.


Assuntos
Suplementos Nutricionais , Regulação da Expressão Gênica , MicroRNAs/metabolismo , Proteínas do Leite/uso terapêutico , Músculo Esquelético/metabolismo , Atrofia Muscular/prevenção & controle , Restrição Física/efeitos adversos , Bebidas , Biópsia por Agulha , Desjejum , Estudos de Coortes , Perfilação da Expressão Gênica , Humanos , Joelho , Extremidade Inferior , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/patologia , Atrofia Muscular/etiologia , Atrofia Muscular/metabolismo , Atrofia Muscular/patologia , Músculo Quadríceps
14.
Am J Physiol Cell Physiol ; 314(4): C389-C403, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29341790

RESUMO

Platelet-derived growth factor receptor (PDGFR) signaling plays an important role in the fundamental biological activities of many cells that compose musculoskeletal tissues. However, little is known about the role of PDGFR signaling during tendon growth and remodeling in adult animals. Using the hindlimb synergist ablation model of tendon growth, our objectives were to determine the role of PDGFR signaling in the adaptation of tendons subjected to a mechanical growth stimulus, as well as to investigate the biological mechanisms behind this response. We demonstrate that both PDGFRs, PDGFRα and PDGFRß, are expressed in tendon fibroblasts and that the inhibition of PDGFR signaling suppresses the normal growth of tendon tissue in response to mechanical growth cues due to defects in fibroblast proliferation and migration. We also identify membrane type-1 matrix metalloproteinase (MT1-MMP) as an essential proteinase for the migration of tendon fibroblasts through their extracellular matrix. Furthermore, we report that MT1-MMP translation is regulated by phosphoinositide 3-kinase/Akt signaling, while ERK1/2 controls posttranslational trafficking of MT1-MMP to the plasma membrane of tendon fibroblasts. Taken together, these findings demonstrate that PDGFR signaling is necessary for postnatal tendon growth and remodeling and that MT1-MMP is a critical mediator of tendon fibroblast migration and a potential target for the treatment of tendon injuries and diseases.


Assuntos
Fibroblastos/enzimologia , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Transdução de Sinais , Traumatismos dos Tendões/enzimologia , Tendões/enzimologia , Tendões/crescimento & desenvolvimento , Animais , Becaplermina/farmacologia , Benzimidazóis/farmacologia , Movimento Celular , Proliferação de Células , Modelos Animais de Doenças , Matriz Extracelular/enzimologia , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fibroblastos/efeitos dos fármacos , Fibroblastos/patologia , Masculino , Metaloproteinase 14 da Matriz/genética , Metaloproteinase 14 da Matriz/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fosfatidilinositol 3-Quinase/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Quinolinas/farmacologia , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/antagonistas & inibidores , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Receptor beta de Fator de Crescimento Derivado de Plaquetas/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacos , Traumatismos dos Tendões/genética , Traumatismos dos Tendões/patologia , Tendões/efeitos dos fármacos , Tendões/patologia
15.
Physiol Rep ; 5(24)2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29263116

RESUMO

Sestrins (1, 2, 3) are a family of stress-inducible proteins capable of attenuating oxidative stress, regulating metabolism, and stimulating autophagy. Sequestosome1 (p62) is also a stress-inducible multifunctional protein acting as a signaling hub for oxidative stress and selective autophagy. It is unclear whether Sestrin and p62Ser403 are regulated acutely or chronically by resistance exercise (RE) or training (RT) in human skeletal muscle. Therefore, the acute and chronic effects of RE on Sestrin and p62 in human skeletal muscle were examined through two studies. In Study 1, nine active men (22.1 ± 2.2 years) performed a bout of single-leg strength exercises and muscle biopsies were collected before, 2, 24, and 48 h after exercise. In Study 2, 10 active men (21.3 ± 1.9 years) strength trained for 12 weeks (2 days per week) and biopsies were collected pre- and post-training. Acutely, 2 h postexercise, phosphorylation of p62Ser403 was downregulated, while there was a mobility shift of Sestrin2, indicative of increased phosphorylation. Forty-eight hours postexercise, the protein expression of both Sestrin1 and total p62 increased. Chronic exercise had no impact on the gene or protein expression of Sestrin2/3 or p62, but Sestrin1 protein was upregulated. These findings demonstrated an inverse relationship between Sestrin2 and p62 phosphorylation after a single bout of RE, indicating they are transiently regulated. Contrarily, 12 weeks of RT increased protein expression of Sestrin1, suggesting that despite the strong sequence homology of the Sestrin family, they are differentially regulated in response to acute RE and chronic RT.


Assuntos
Músculo Esquelético/metabolismo , Proteínas Nucleares/metabolismo , Processamento de Proteína Pós-Traducional , Treinamento de Resistência , Proteína Sequestossoma-1/metabolismo , Humanos , Masculino , Músculo Esquelético/fisiologia , Fosforilação , Adulto Jovem
16.
PLoS One ; 12(7): e0181594, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28750051

RESUMO

A subset of short non-coding RNAs, microRNAs (miRs), have been identified in the regulation of skeletal muscle hypertrophy and atrophy. Expressed within cells, miRs are also present in circulation (c-miR) and have a putative role in cross-tissue signalling. The aim of this study was to examine the impact of a single bout of high intensity resistance exercise (RE) on skeletal muscle and circulatory miRs harvested simultaneously. Resistance trained males (n = 9, 24.6 ± 4.9 years) undertook a single bout of high volume RE with venous blood and muscle biopsies collected before, 2 and 4hr post-exercise. Real time polymerase chain reaction (Rt-PCR) analyses was performed on 30 miRs that have previously been shown to be required for skeletal muscle function. Of these, 6 miRs were significantly altered within muscle following exercise; miR-23a, -133a, -146a, -206, -378b and 486. Analysis of these same miRs in circulation demonstrated minimal alterations with exercise, although c-miR-133a (~4 fold, p = 0.049) and c-miR-149 (~2.4 fold; p = 0.006) were increased 4hr post-exercise. Thus a single bout of RE results in the increased abundance of a subset of miRs within the skeletal muscle, which was not evident in plasma. The lack a qualitative agreement in the response pattern of intramuscular and circulating miR expression suggests the analysis of circulatory miRs is not reflective of the miR responses within skeletal muscle after exercise.


Assuntos
Exercício/fisiologia , Perfilação da Expressão Gênica , MicroRNAs/sangue , MicroRNAs/genética , Músculo Esquelético/metabolismo , Treinamento de Resistência , Humanos , Masculino , Adulto Jovem
17.
Skelet Muscle ; 7(1): 5, 2017 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-28381300

RESUMO

BACKGROUND: The spatial organization of eukaryotic genomes facilitates and reflects the underlying nuclear processes that are occurring in the cell. As such, the spatial organization of a genome represents a window on the genome biology that enables analysis of the nuclear regulatory processes that contribute to mammalian development. METHODS: In this study, Hi-C and RNA-seq were used to capture the genome organization and transcriptome in mouse muscle progenitor cells (C2C12 myoblasts) before and after differentiation to myotubes, in the presence or absence of the cytidine analogue AraC. RESULTS: We observed significant local and global developmental changes despite high levels of correlation between the myotubes and myoblast genomes. Notably, the genes that exhibited the greatest variation in transcript levels between the different developmental stages were predominately within the euchromatic compartment. There was significant re-structuring and changes in the expression of replication-dependent histone variants within the HIST1 locus. Finally, treating terminally differentiated myotubes with AraC resulted in additional changes to the transcriptome and 3D genome organization of sets of genes that were all involved in pyroptosis. CONCLUSIONS: Collectively, our results provide evidence for muscle cell-specific responses to developmental and environmental stimuli mediated through a chromatin structure mechanism.


Assuntos
Diferenciação Celular , Cromatina/química , Genoma , Fibras Musculares Esqueléticas/metabolismo , Mioblastos Esqueléticos/metabolismo , Animais , Linhagem Celular , Cromatina/genética , Cromatina/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Código das Histonas , Camundongos , Fibras Musculares Esqueléticas/citologia , Mioblastos Esqueléticos/citologia , Transcriptoma
18.
Nutrients ; 9(4)2017 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-28368340

RESUMO

Postprandial inflammation and endotoxaemia are determinants of cardiovascular and metabolic disease risk which are amplified by high fat meals. We aimed to examine the determinants of postprandial inflammation and endotoxaemia in older and younger adults following a high fat mixed meal. In a randomised cross-over trial, healthy participants aged 20-25 and 60-75 years (n = 15/group) consumed a high-fat breakfast and a low-fat breakfast. Plasma taken at baseline and post-meal for 5 h was analysed for circulating endotoxin, cytokines (monocyte chemotactic protein-1 (MCP-1), interleukin (IL)-1ß, IL-6, and tumour necrosis factor-alpha (TNF-α)), lipopolysaccharide binding protein (LBP), and inflammatory gene expression in peripheral blood mononuclear cells (PBMC). Older subjects had lower baseline PBMC expression of Glutathione peroxidase 1 (GPX-1) but greater insulin-like growth factor-binding protein 3 (IGFBP3) and circulating MCP-1 compared to younger subjects. After either meal, there were no age differences in plasma, chylomicron endotoxin, or plasma LBP concentrations, nor in inflammatory cytokine gene and protein expression (MCP-1, IL-1ß, and TNF-α). Unlike younger participants, the older group had decreased superoxide dismutase (SOD)-2 expression after the meals. After a high-fat meal, older adults have no increased inflammatory or endotoxin response, but an altered oxidative stress gene response compared with younger adults. Healthy older adults, without apparent metabolic dysfunction, have a comparable postprandial inflammatory and endotoxaemia response to younger adults.


Assuntos
Doenças Cardiovasculares/etiologia , Dieta Hiperlipídica/efeitos adversos , Fenômenos Fisiológicos da Nutrição do Idoso , Regulação da Expressão Gênica no Desenvolvimento , Leucócitos Mononucleares/metabolismo , Doenças Metabólicas/etiologia , Vasculite/etiologia , Adulto , Idoso , Biomarcadores/sangue , Biomarcadores/metabolismo , Desjejum , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/imunologia , Doenças Cardiovasculares/metabolismo , Estudos de Coortes , Estudos Cross-Over , Feminino , Humanos , Mediadores da Inflamação/sangue , Mediadores da Inflamação/metabolismo , Leucócitos Mononucleares/imunologia , Masculino , Doenças Metabólicas/epidemiologia , Doenças Metabólicas/imunologia , Doenças Metabólicas/metabolismo , Pessoa de Meia-Idade , Nova Zelândia/epidemiologia , Período Pós-Prandial , Fatores de Risco , Vasculite/imunologia , Vasculite/metabolismo , Vasculite/fisiopatologia , Adulto Jovem
19.
Cell Mol Life Sci ; 74(14): 2537-2545, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28220207

RESUMO

The mammalian target of rapamycin (mTOR) complex exerts a pivotal role in protein anabolism and cell growth. Despite its importance, few studies adequately address the complexity of phosphorylation of the mTOR protein itself to enable conclusions to be drawn on the extent of kinase activation following this event. In particular, a large number of studies in the skeletal muscle biology field have measured Serine 2448 (Ser2448) phosphorylation as a proxy of mTOR kinase activity. However, the evidence to be described is that Ser2448 is not a measure of mTOR kinase activity nor is a target of AKT activity and instead has inhibitory effects on the kinase that is targeted by the downstream effector p70S6K in a negative feedback loop mechanism, which is evident when revisiting muscle research studies. It is proposed that this residue modification acts as a fine-tuning mechanism that has been gained during vertebrate evolution. In conclusion, it is recommended that Ser2448 is an inadequate measure and that preferential analysis of mTORC1 activation should focus on the downstream and effector proteins, including p70S6K and 4E-BP1, along mTOR protein partners that bind to mTOR protein to form the active complexes 1 and 2.


Assuntos
Músculos/metabolismo , Serina/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Animais , Biomarcadores/metabolismo , Exercício , Humanos , Fosforilação
20.
Nutr Metab (Lond) ; 14: 9, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28127382

RESUMO

BACKGROUND: The milk fat globule membrane (MFGM) is primarily composed of polar phospho- and sphingolipids, which have established biological effects on neuroplasticity. The present study aimed to investigate the effect of dietary MFGM supplementation on the neuromuscular system during post-natal development. METHODS: Growing rats received dietary supplementation with bovine-derived MFGM mixtures consisting of complex milk lipids (CML), beta serum concentrate (BSC) or a complex milk lipid concentrate (CMLc) (which lacks MFGM proteins) from post-natal day 10 to day 70. RESULTS: Supplementation with MFGM mixtures enriched in polar lipids (BSC and CMLc, but not CML) increased the plasma phosphatidylcholine (PC) concentration, with no effect on plasma phosphatidylinositol (PI), phosphatidylethanolamine (PE), phosphatidylserine (PS) or sphingomyelin (SM). In contrast, muscle PC was reduced in rats receiving supplementation with both BSC and CMLc, whereas muscle PI, PE, PS and SM remained unchanged. Rats receiving BSC and CMLc (but not CML) displayed a slow-to-fast muscle fibre type profile shift (MyHCI → MyHCIIa) that was associated with elevated expression of genes involved in myogenic differentiation (myogenic regulatory factors) and relatively fast fibre type specialisation (Myh2 and Nfatc4). Expression of neuromuscular development genes, including nerve cell markers, components of the synaptogenic agrin-LRP4 pathway and acetylcholine receptor subunits, was also increased in muscle of rats supplemented with BSC and CMLc (but not CML). CONCLUSIONS: These findings demonstrate that dietary supplementation with bovine-derived MFGM mixtures enriched in polar lipids can promote neuromuscular development during post-natal growth in rats, leading to shifts in adult muscle phenotype.

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