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1.
PLoS Comput Biol ; 16(7): e1008079, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32730244

RESUMO

Exercise training elicits profound metabolic adaptations in skeletal muscle cells. A key molecule in coordinating these adaptations is AMP-activated protein kinase (AMPK), whose activity increases in response to cellular energy demand. AMPK activity dynamics are primarily controlled by the adenine nucleotides ADP and AMP, but how each contributes to its control in skeletal muscle during exercise is unclear. We developed and validated a mathematical model of AMPK signaling dynamics, and then applied global parameter sensitivity analyses with data-informed constraints to predict that AMPK activity dynamics are determined principally by ADP and not AMP. We then used the model to predict the effects of two additional direct-binding activators of AMPK, ZMP and Compound 991, further validating the model and demonstrating its applicability to understanding AMPK pharmacology. The relative effects of direct-binding activators can be understood in terms of four properties, namely their concentrations, binding affinities for AMPK, abilities to enhance AMPK phosphorylation, and the magnitudes of their allosteric activation of AMPK. Despite AMP's favorable values in three of these four properties, ADP is the dominant controller of AMPK activity dynamics in skeletal muscle during exercise by virtue of its higher concentration compared to that of AMP.


Assuntos
Proteínas Quinases Ativadas por AMP , Difosfato de Adenosina , Exercício Físico/fisiologia , Músculo Esquelético , Proteínas Quinases Ativadas por AMP/química , Proteínas Quinases Ativadas por AMP/metabolismo , Difosfato de Adenosina/química , Difosfato de Adenosina/metabolismo , Difosfato de Adenosina/farmacocinética , Animais , Biologia Computacional , Humanos , Camundongos , Modelos Biológicos , Músculo Esquelético/enzimologia , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , Transdução de Sinais/fisiologia
2.
Food Chem ; 330: 127246, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32526647

RESUMO

Previously we purified and characterized a sarcoplasmic serine proteinase (SSP) from the belly muscle of the threadfin bream as a modori-inducing proteinase. In our attempt to clarify the structure and physiological functions of SSP, we successfully cloned the full-length cDNA of SSP (ORF 726 bp). The deduced amino acid sequence of SSP (241 residues) was highly homologous to fish trypsinogen. The distribution of SSP mRNA and the proteinase activity in the tissue indicated that SSP was mainly synthesized and existed in the digestive system under physiological conditions. After ice storage of the threadfin bream without gutting, a high SSP activity was detected only in the belly muscle because of SSP leaked from the viscera. Therefore, it is desirable to use edible proteinase inhibitor to inactivate the leaked SSP during production of surimi-based products or to take effective measures to prevent the proteinase leakage during post-harvest storage.


Assuntos
Serina Proteases/metabolismo , Vísceras/enzimologia , Sequência de Aminoácidos , Animais , Clonagem Molecular , Peixes/metabolismo , Gelo , Músculo Esquelético/enzimologia , Proteólise , Alimentos Marinhos , Distribuição Tecidual
3.
Clin Sci (Lond) ; 134(10): 1167-1180, 2020 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-32458968

RESUMO

In the present study, we evaluated the metabolic effects of green tea polyphenols (GTPs) in high-fat diet (HFD) fed Zucker fatty (ZF) rats, in particular the effects of GTP on skeletal muscle insulin sensitivity. Body weight, visceral fat, glucose tolerance, lipid profiles and whole-body insulin sensitivity were measured in HFD-fed ZF rats after 8-week-treatment with GTP (200 mg/kg of body weight) or saline (5 ml/kg of body weight). Zucker lean rats were studied as controls. Ex vivo insulin-mediated muscle glucose uptake was assessed. Immunoblotting was used to evaluate the expression of key insulin signalling proteins in skeletal muscle. GTP treatment attenuated weight gain (P<0.05) and visceral fat accumulation (27.6%, P<0.05), and significantly reduced fasting serum glucose (P<0.05) and insulin (P<0.01) levels. Homoeostasis model assessment of insulin resistance (HOMA-IR), a measure of insulin resistance, was lower (P<0.01) in GTP-treated animals compared with ZF controls. Moreover, insulin-stimulated glucose uptake by isolated soleus muscle was increased (P<0.05) in GTP-ZF rats compared with ZF-controls. GTP treatment attenuated the accumulation of ectopic lipids (triacyl- and diacyl-glycerols), enhanced the expression and translocation of glucose transporter-4, and decreased pSer612IRS-1 and increased pSer473Akt2 expression in skeletal muscle. These molecular changes were also associated with significantly decreased activation of the inhibitory (muscle-specific) protein kinase (PKC) isoform, PKC-θ. Taken together, the present study has shown that regular ingestion of GTP exerts a number of favourable metabolic and molecular effects in an established animal model of obesity and insulin resistance. The benefits of GTP are mediated in part by inhibiting PKC-θ and improving muscle insulin sensitivity.


Assuntos
Resistência à Insulina , Insulina/metabolismo , Músculo Esquelético/metabolismo , Polifenóis/farmacologia , Transdução de Sinais , Chá/química , Adiposidade/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Glucose/metabolismo , Teste de Tolerância a Glucose , Transportador de Glucose Tipo 4/metabolismo , Gordura Intra-Abdominal/efeitos dos fármacos , Gordura Intra-Abdominal/metabolismo , Isoenzimas/metabolismo , Masculino , Proteínas Musculares/metabolismo , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/enzimologia , Fosforilação/efeitos dos fármacos , Proteína Quinase C/metabolismo , Transporte Proteico/efeitos dos fármacos , Ratos Zucker
4.
Artigo em Inglês | MEDLINE | ID: mdl-32348180

RESUMO

The ubiquitous calpains, calpain-1 and -2, play important roles in Ca2+-dependent membrane repair. Mechanically active tissues like skeletal muscle are particularly reliant on mechanisms to repair and remodel membrane injury, such as those caused by eccentric damage. We demonstrate that calpain-1 and -2 are master effectors of Ca2+-dependent repair of mechanical plasma membrane scrape injuries, although they are dispensable for repair/removal of small wounds caused by pore-forming agents. Using CRISPR gene-edited human embryonic kidney 293 (HEK293) cell lines, we established that loss of both calpains-1 and -2 (CAPNS1-/-) virtually ablates Ca2+-dependent repair of mechanical scrape injuries but does not affect injury or recovery from perforation by streptolysin-O or saponin. In contrast, cells with targeted knockout of either calpain-1 (CAPN1-/-) or -2 (CAPN2-/-) show near-normal repair of mechanical injuries, inferring that both calpain-1 and calpain-2 are equally capable of conducting the cascade of proteolytic cleavage events to reseal a membrane injury, including that of the known membrane repair agent dysferlin. A severe muscular dystrophy in a murine model with skeletal muscle knockout of Capns1 highlights vital roles for calpain-1 and/or -2 for health and viability of skeletal muscles not compensated for by calpain-3 (CAPN3). We propose that the dystrophic phenotype relates to loss of maintenance of plasma membrane/cytoskeletal networks by calpains-1 and -2 in response to directed and dysfunctional Ca2+-signaling, pathways hyperstimulated in the context of membrane injury. With CAPN1 variants associated with spastic paraplegia, a severe dystrophy observed with muscle-specific loss of calpain-1 and -2 activity identifies CAPN2 and CAPNS1 as plausible candidate neuromuscular disease genes.


Assuntos
Calpaína/deficiência , Membrana Celular/enzimologia , Músculo Esquelético/enzimologia , Distrofia Muscular do Cíngulo dos Membros/enzimologia , Distrofia Muscular Animal/enzimologia , Animais , Proteínas de Bactérias/farmacologia , Sinalização do Cálcio , Calpaína/genética , Membrana Celular/efeitos dos fármacos , Membrana Celular/patologia , Modelos Animais de Doenças , Disferlina/deficiência , Disferlina/genética , Feminino , Células HEK293 , Humanos , Masculino , Camundongos Knockout , Músculo Esquelético/patologia , Distrofia Muscular do Cíngulo dos Membros/genética , Distrofia Muscular do Cíngulo dos Membros/patologia , Distrofia Muscular Animal/genética , Distrofia Muscular Animal/patologia , Saponinas/farmacologia , Índice de Gravidade de Doença , Estreptolisinas/farmacologia
5.
Int J Sports Med ; 41(6): 349-359, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32162291

RESUMO

It is universally accepted that resistance training promotes increases in muscle strength and hypertrophy in younger and older populations. Although less investigated, studies largely suggest resistance training results in lower skeletal muscle mitochondrial volume; a phenomenon which has been described as a "dilution of the mitochondrial volume" via resistance training. While this phenomenon is poorly understood, it is likely a result of muscle fiber hypertrophy outpacing mitochondrial biogenesis. Critically, there is no evidence to suggest resistance training promotes a net loss in mitochondria. Further, given the numerous reports suggesting resistance training does not decrease and may even increase VO2max in previously untrained individuals, it is plausible certain aspects of mitochondrial function may be enhanced with resistance training, and this area warrants further research consideration. Finally, there are emerging data suggesting resistance training may affect mitochondrial dynamics. The current review will provide an in-depth discussion of these topics and posit future research directions which can further our understanding of how resistance training may affect skeletal muscle mitochondrial physiology.


Assuntos
Mitocôndrias Musculares/fisiologia , Músculo Esquelético/citologia , Músculo Esquelético/fisiologia , Treinamento de Resistência , Adaptação Fisiológica , Citrato (si)-Sintase/metabolismo , Humanos , Fibras Musculares de Contração Rápida/fisiologia , Fibras Musculares de Contração Lenta/fisiologia , Músculo Esquelético/enzimologia , Biogênese de Organelas
6.
PLoS One ; 15(3): e0229933, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32191723

RESUMO

PURPOSE: Creatine Kinase (CK) reaction plays an important role in energy metabolism and estimate of its reaction rate constant in heart provides important insight into cardiac energetics. Fast saturation transfer method ([Formula: see text] nominal) to measure CK reaction rate constant (kf) was previously demonstrated in open chest swine hearts. The goal of this work is to further develop this method for measuring the kf in human myocardium at 7T. [Formula: see text] approach is combined with 1D-ISIS/2D-CSI for in vivo spatial localization and myocardial CK forward rate constant was then measured in 7 volunteers at 7T. METHODS: [Formula: see text] method uses two partially relaxed saturation transfer (ST) spectra and correction factor to determine CK rate constant. Correction factor is determined by numerical simulation of Bloch McConnell equations using known spin and experimental parameters. Optimal parameters and error estimate in calculation of CK reaction rate constant were determined by simulations. The technique was validated in calf muscles by direct comparison with saturation transfer measurements. [Formula: see text] pulse sequence was incorporated with 1D-image selected in vivo spectroscopy, combined with 2D-chemical shift spectroscopic imaging (1D-ISIS/2D-CSI) for studies in heart. The myocardial CK reaction rate constant was then measured in 7 volunteers. RESULTS: Skeletal muscle kf determined by conventional approach and [Formula: see text] approach were the same 0.31 ± 0.02 s-1 and 0.30 ± 0.04 s-1 demonstrating the validity of the technique. Results are reported as mean ± SD. Myocardial CK reaction rate constant was 0.29 ± 0.05 s-1, consistent with previously reported studies. CONCLUSION: [Formula: see text] method enables acquisition of 31P saturation transfer MRS under partially relaxed conditions and enables 2D-CSI of kf in myocardium. This work enables applications for in vivo CSI imaging of energetics in heart and other organs in clinically relevant acquisition time.


Assuntos
Creatina Quinase/isolamento & purificação , Creatina/metabolismo , Coração/diagnóstico por imagem , Músculo Esquelético/enzimologia , Trifosfato de Adenosina/metabolismo , Adulto , Creatina Quinase/metabolismo , Metabolismo Energético/fisiologia , Feminino , Coração/fisiologia , Humanos , Cinética , Imagem por Ressonância Magnética/métodos , Espectroscopia de Ressonância Magnética , Masculino , Músculo Esquelético/metabolismo , Miocárdio/enzimologia , Miocárdio/patologia , Isótopos de Fósforo/química
7.
Am J Physiol Renal Physiol ; 318(4): F1030-F1040, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32150446

RESUMO

Manipulation of circulating histidine-containing dipeptides (HCD) has been shown to affect the development of diabetes and early-stage diabetic nephropathy (DN). The aim of the present study was to investigate whether such interventions, which potentially alter levels of circulating HCD, also affect the development of advanced-stage DN. Two interventions, aerobic exercise training and overexpression of the human carnosinase-1 (hCN1) enzyme, were tested. BTBR ob/ob mice were either subjected to aerobic exercise training (20 wk) or genetically manipulated to overexpress hCN1, and different diabetes- and DN-related markers were compared with control ob/ob and healthy (wild-type) mice. An acute exercise study was performed to elucidate the effect of obesity, acute running, and hCN1 overexpression on plasma HCD levels. Chronic aerobic exercise training did not affect the development of diabetes or DN, but hCN1 overexpression accelerated hyperlipidemia and aggravated the development of albuminuria, mesangial matrix expansion, and glomerular hypertrophy of ob/ob mice. In line, plasma, kidney, and muscle HCD were markedly lower in ob/ob versus wild-type mice, and plasma and kidney HCD in particular were lower in ob/ob hCN1 versus ob/ob mice but were unaffected by aerobic exercise. In conclusion, advanced glomerular damage is accelerated in mice overexpressing the hCN1 enzyme but not protected by chronic exercise training. Interestingly, we showed, for the first time, that the development of DN is closely linked to renal HCD availability. Further research will have to elucidate whether the stimulation of renal HCD levels can be a therapeutic strategy to reduce the risk for developing DN.


Assuntos
Nefropatias Diabéticas/enzimologia , Dipeptidases/biossíntese , Terapia por Exercício , Glomérulos Renais/enzimologia , Músculo Esquelético/enzimologia , Obesidade/enzimologia , Animais , Nefropatias Diabéticas/genética , Nefropatias Diabéticas/patologia , Dipeptidases/genética , Dipeptídeos/metabolismo , Modelos Animais de Doenças , Indução Enzimática , Histidina/análogos & derivados , Histidina/metabolismo , Humanos , Glomérulos Renais/patologia , Camundongos Transgênicos , Músculo Esquelético/patologia , Obesidade/complicações , Obesidade/genética , Obesidade/patologia , Fatores de Tempo
8.
Sud Med Ekspert ; 63(1): 31-35, 2020.
Artigo em Russo | MEDLINE | ID: mdl-32040085

RESUMO

Aim of the study is to identify patterns of variations of the fluorescence intensity of NADH (reduced nicotinamide adenine dinucleotide) and FAD (oxidized flavin adenine dinucleotide) in the skeletal muscle depending on the time since death. For the evaluation of fluorescence intensity of the studied coenzymes, laser-induced spectroscopy in situ was used. We revealed the dynamic of the fluorescence intensity of NADH and FAD in the skeletal muscle of a rat at different times during the post-mortem period, and theoretically justified the observed phenomena. The results obtained allow us to consider the studied indicators as a potential criterion for determining the post-mortem interval.


Assuntos
Flavina-Adenina Dinucleotídeo/análise , Fluorescência , Músculo Esquelético/enzimologia , NAD/análise , Mudanças Depois da Morte , Animais , Autopsia , Ratos
9.
Nature ; 578(7796): 605-609, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32051584

RESUMO

The activation of adenosine monophosphate-activated protein kinase (AMPK) in skeletal muscle coordinates systemic metabolic responses to exercise1. Autophagy-a lysosomal degradation pathway that maintains cellular homeostasis2-is upregulated during exercise, and a core autophagy protein, beclin 1, is required for AMPK activation in skeletal muscle3. Here we describe a role for the innate immune-sensing molecule Toll-like receptor 9 (TLR9)4, and its interaction with beclin 1, in exercise-induced activation of AMPK in skeletal muscle. Mice that lack TLR9 are deficient in both exercise-induced activation of AMPK and plasma membrane localization of the GLUT4 glucose transporter in skeletal muscle, but are not deficient in autophagy. TLR9 binds beclin 1, and this interaction is increased by energy stress (glucose starvation and endurance exercise) and decreased by a BCL2 mutation3,5 that blocks the disruption of BCL2-beclin 1 binding. TLR9 regulates the assembly of the endolysosomal phosphatidylinositol 3-kinase complex (PI3KC3-C2)-which contains beclin 1 and UVRAG-in skeletal muscle during exercise, and knockout of beclin 1 or UVRAG inhibits the cellular AMPK activation induced by glucose starvation. Moreover, TLR9 functions in a muscle-autonomous fashion in ex vivo contraction-induced AMPK activation, glucose uptake and beclin 1-UVRAG complex assembly. These findings reveal a heretofore undescribed role for a Toll-like receptor in skeletal-muscle AMPK activation and glucose metabolism during exercise, as well as unexpected crosstalk between this innate immune sensor and autophagy proteins.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Proteína Beclina-1/metabolismo , Músculo Esquelético/metabolismo , Condicionamento Físico Animal/fisiologia , Receptor Toll-Like 9/metabolismo , Animais , Autofagia , Ativação Enzimática , Exercício Físico , Glucose/metabolismo , Humanos , Masculino , Camundongos , Modelos Animais , Músculo Esquelético/enzimologia , Fosfatidilinositol 3-Quinase/metabolismo , Receptor Toll-Like 9/deficiência , Receptor Toll-Like 9/genética , Proteínas Supressoras de Tumor/metabolismo
10.
Am J Clin Nutr ; 111(3): 570-579, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31968072

RESUMO

BACKGROUND: Cancer cachexia is characterized by weight loss, especially ongoing skeletal muscle loss, and is associated with poor patient outcomes. However, the molecular mechanism of skeletal muscle wasting is not fully understood. OBJECTIVES: We aimed to investigate muscle fiber morphology and proteolysis system activity changes that may account for cancer cachexia and to relate these changes to patients' clinical phenotypes. METHODS: We divided 39 patients with resectable gastric cancer into 4 groups based on the presence of cachexia (weight loss) and/or sarcopenia (low muscularity), including a noncachexia/nonsarcopenia group (N, n = 10), a cachexia/sarcopenia group (CS, n = 13), a cachexia/nonsarcopenia group (C, n = 9), and a noncachexia/sarcopenia group (S, n = 7). Rectus abdominis muscle biopsy specimens were obtained intraoperatively. Muscle fiber size, ultrastructural architecture, and the expression of autophagic-lysosomal system (ALS) and ubiquitin proteasome system (UPS) markers were assayed. RESULTS: Mean ± SD muscle fiber cross-sectional areas were significantly decreased in the CS (460 ± 120 µm2) and S groups (480 ± 135 µm2) compared with the N (1615 ± 388 µm2, both P < 0.05) and C groups (1219 ± 302 µm2, both P < 0.05). In the C, S, and CS groups, the muscle exhibited tissue disorganization and autophagosome formation to different degrees. The levels of ALS and UPS markers were significantly increased in the CS, C, and S groups compared with the N group. Alterations in muscle fiber morphology and increased ALS and UPS activity were related to severe muscle loss, but not weight loss. CONCLUSIONS: The ALS and UPS are simultaneously activated in cancer cachexia and may play coordinated roles in cachexia-induced muscle loss.


Assuntos
Autofagia , Caquexia/enzimologia , Lisossomos/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Sarcopenia/enzimologia , Neoplasias Gástricas/enzimologia , Adulto , Idoso , Caquexia/genética , Caquexia/patologia , Caquexia/fisiopatologia , Feminino , Humanos , Lisossomos/enzimologia , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/citologia , Músculo Esquelético/enzimologia , Músculo Esquelético/patologia , Complexo de Endopeptidases do Proteassoma/genética , Sarcopenia/metabolismo , Sarcopenia/patologia , Sarcopenia/fisiopatologia , Neoplasias Gástricas/genética , Neoplasias Gástricas/patologia , Neoplasias Gástricas/fisiopatologia , Ubiquitina/metabolismo
11.
Food Chem ; 314: 126203, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31978718

RESUMO

The activity, expression and S-nitrosylation of glycogen phosphorylase (GP), phosphofructokinase (PFK) and pyruvate kinase (PK) was compared between pale, soft and exudative (PSE) and red, firm and non-exudative (RFN) pork. The nitric oxide synthase (NOS) activity of RFN pork was higher than PSE pork (P < 0.05). Glycogen and lactic acid content were significantly different between PSE and RFN samples at 1 h postmortem (P < 0.05). Compared to PSE pork, RFN pork had lower activities and higher S-nitrosylation levels of GP, PFK and PK (P < 0.05). Moreover, GP expression in RFN pork was lower (P < 0.05) while no significant differences of PFK and PK expression were observed between these two groups. These data suggest that protein S-nitrosylation can presumably regulate glycolysis by modulating glycolytic enzymes activities and then regulate the development of PSE pork.


Assuntos
Glicólise , Músculo Esquelético/metabolismo , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico/metabolismo , Carne de Porco/análise , Animais , Cor , Glicogênio/metabolismo , Glicogênio Fosforilase/metabolismo , Músculo Esquelético/enzimologia , Fosfofrutoquinases/metabolismo , Piruvato Quinase/metabolismo , Suínos
12.
Molecules ; 25(1)2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31906305

RESUMO

Lipid metabolism dysfunction and obesity are serious health issues to human beings. The current study investigated the effects of hyperbaric oxygen (HBO) against high fat diet (HFD)-induced lipid metabolism dysfunction and the roles of L-carnitine. C57/B6 mice were fed with HFD or normal chew diet, with or without HBO treatment. Histopathological methods were used to assess the adipose tissues, serum free fatty acid (FFA) levels were assessed with enzymatic methods, and the endogenous circulation and skeletal muscle L-carnitine levels were assessed with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Additionally, western blotting was used to assess the expression levels of PPARα, CPT1b, pHSL/HSL, and UCP1. HFD treatment increased body/adipose tissue weight, serum FFA levels, circulation L-carnitines and decreased skeletal muscle L-carnitine levels, while HBO treatment alleviated such changes. Moreover, HFD treatment increased fatty acid deposition in adipose tissues and decreased the expression of HSL, while HBO treatment alleviated such changes. Additionally, HFD treatment decreased the expression levels of PPARα and increased those of CPT1b in skeletal muscle, while HBO treatment effectively reverted such changes as well. In brown adipose tissues, HFD increased the expression of UCP1 and the phosphorylation of HSL, which was abolished by HBO treatment as well. In summary, HBO treatment may alleviate HFD-induced fatty acid metabolism dysfunction in C57/B6 mice, which seems to be associated with circulation and skeletal muscle L-carnitine levels and PPARα expression.


Assuntos
Tecido Adiposo/metabolismo , Carnitina/metabolismo , Dieta Hiperlipídica/efeitos adversos , Ácidos Graxos/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Tecido Adiposo/citologia , Animais , Carnitina/sangue , Carnitina/química , Carnitina O-Palmitoiltransferase/metabolismo , Cromatografia Líquida , Oxigenação Hiperbárica , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético/enzimologia , Músculo Esquelético/metabolismo , Obesidade/tratamento farmacológico , PPAR alfa/metabolismo , Fosforilação , Esterol Esterase/química , Esterol Esterase/metabolismo , Espectrometria de Massas em Tandem , Proteína Desacopladora 1/metabolismo
13.
J Dairy Sci ; 103(3): 2847-2863, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31928756

RESUMO

Branched-chain amino acids (BCAA) are major components of milk protein and important precursors for nonessential AA. Thus, the BCAA transport and break-down play a key role in the metabolic adaptation to the high nutrient demands in lactation. However, in monogastrics, increased BCAA levels have been linked with obesity and certain metabolic disorders such as impaired insulin sensitivity. Our objective was to study the effect of over-conditioning at calving on plasma BCAA levels as well as the tissue abundance of the most relevant BCAA transporters and degrading enzymes in dairy cows during late pregnancy and early lactation. Thirty-eight Holstein cows were allocated 15 wk antepartum to either a normal- (NBCS) or over-conditioned (HBCS) group, receiving 6.8 or 7.2 MJ of NEL/kg of DM, respectively, during late lactation to reach the targeted differences in body condition score (BCS) and back fat thickness (BFT; NBCS: BCS <3.5, BFT <1.2 cm; HBCS: BCS >3.75, BFT >1.4 cm) until dry-off. During the dry period and next lactation, cows were fed the same diets, whereby differences in BCS and BFT were maintained: prepartum means were 3.16 ± 0.06 and 1.03 ± 0.07 cm (NBCS) vs. 3.77 ± 0.08 and 1.89 ± 0.11 cm (HBCS), postpartum means were 2.89 ± 0.06 and 0.81 ± 0.05 cm (NBCS) vs. 3.30 ± 0.06 and 1.38 ± 0.08 cm (HBCS). Blood and biopsies from liver, semitendinosus muscle, and subcutaneous adipose tissue (scAT) were sampled at d 49 antepartum, 3, 21, and 84 postpartum. Free BCAA were analyzed and the mRNA abundance of solute carrier family 1 member 5 (SLC1A5), SLC7A5, and SLC38A2 as well as branched-chain aminotransferase 2 (BCAT2), branched-chain α-keto acid dehydrogenase E1α (BCKDHA), and branched-chain α-keto acid dehydrogenase E1ß (BCKDHB) as well as the protein abundance of BCKDHA were assessed. Concentrations of all BCAA changed with time, most markedly in HBCS cows, with a nadir around calving. Apart from Ile, neither individual nor total BCAA differed between groups. The HBCS group had greater BCKDHA mRNA as well as higher prepartum BCKDHA protein abundance in scAT than NBCS cows, pointing to a greater oxidative capacity for the irreversible degradation of BCAA transamination products in scAT of over-conditioned cows. Prepartum hepatic BCKDHA protein abundance was lower in HBCS than in NBCS cows. In both groups, SLC1A5, SLC7A5, and BCAT2 mRNA were most abundant in scAT, whereas SLC38A2 was higher in scAT and muscle compared with liver, and BCKDHA and BCKDHB mRNA were greatest in liver and muscle, respectively. Our results indicate that scAT may be a major site of BCAA uptake and initial catabolism, with the former, however, being independent of BCS and time relative to calving in dairy cows.


Assuntos
3-Metil-2-Oxobutanoato Desidrogenase (Lipoamida)/metabolismo , Aminoácidos de Cadeia Ramificada/metabolismo , Bovinos/fisiologia , Leite/química , 3-Metil-2-Oxobutanoato Desidrogenase (Lipoamida)/genética , Sistemas de Transporte de Aminoácidos/genética , Sistemas de Transporte de Aminoácidos/metabolismo , Aminoácidos de Cadeia Ramificada/sangue , Animais , Bovinos/genética , Dieta/veterinária , Feminino , Lactação , Fígado/metabolismo , Músculo Esquelético/enzimologia , Período Pós-Parto , Gravidez , RNA Mensageiro/genética , Gordura Subcutânea/enzimologia
14.
Mar Biotechnol (NY) ; 22(1): 81-93, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31965438

RESUMO

The autophagic lysosomal protein degradation pathway is an evolutionarily conserved pathway, which utilizes lysosomes to degrade and to circulate cell components. Autophagy has been observed in many different types of cells, but its role in skeletal muscle protein degradation has not been thoroughly studied, especially in aquatic species. This study assessed the expression of antioxidant-related signaling genes and the effects of starvation on antioxidant capacity, reactive oxygen species (ROS) content, autophagy-related gene, and autophagosome formation in the skeletal muscle of juvenile Chinese perch after short-term starvation. The results indicated that after starvation for 2 days, the expression of antioxidant-related signaling genes, such as Nrf2 and S6K, was upregulated, while Keap1 was downregulated in the muscle of juvenile Chinese perch. The amounts of antioxidant enzymes ROS, MDA, AHRFR, and ASA and the activities of SOD, CAT, GPx, and GST were increased, and the mRNA levels of GPx, GSTA, GST4A, GSTT1, MnSOD, ZnSOD, and CAT were upregulated. Meanwhile, there was no significant change in the level of LC3-II protein. When starvation was prolonged to 5 days, Nrf2 and S6K1 continued to increase and mTOR and Keap1 significantly decreased; ROS and ASA content continued to be significantly increased, but the MDA and AHRFR content and the SOD, CAT GR, and GPx activities all decreased. The expression of MnSOD, ZnSOD, and GR decreased significantly, and GST4A, GSTT1, and CAT tended to decrease to levels consistent with normal feeding. The expression of all autophagy-related genes except Ulk1 significantly increased, the formation of autophagosomes and autolysosomes was enhanced in muscle, and LC3 protein levels in muscle increased significantly. Our data suggested that the autophagy that occurs in the skeletal muscle tissue of Chinese perch due to dietary deprivation is involved in a series of molecular and physiological responses, including changes in antioxidant signaling molecules, in antioxidant capacity and in autophagy and autophagy-related gene expression.


Assuntos
Autofagia , Privação de Alimentos/fisiologia , Músculo Esquelético/metabolismo , Estresse Oxidativo , Percas/metabolismo , Animais , Antioxidantes/metabolismo , Regulação da Expressão Gênica , Músculo Esquelético/enzimologia , Percas/genética , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais
15.
J Pharmacol Exp Ther ; 372(3): 256-263, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31900320

RESUMO

Excess intramyocellular lipid (IMCL) deposition in skeletal muscle is closely associated with insulin resistance. Pharmacological inhibition of acetyl-CoA carboxylase (ACC) 2 offers a promising approach to treat insulin resistance through stimulation of mitochondrial fatty acid oxidation (FAO) and reduction of IMCL deposition. Previously reported experimental ACC2 inhibitors exhibited plasma glucose-lowering effects in diabetic rodents. However, their antidiabetic action may be potentially biased by off-target effects on triglyceride metabolism or by neurologic side effects. In this study, we investigated a safety profile, target dependency of its action, and antidiabetic efficacy of compound 2e, a novel olefin derivative potent ACC2 selective inhibitor. Four-day administration of suprapharmacological dose of compound 2e did not exhibit any obvious side effects in Sprague-Dawley rats. In db/db mice, single administration of compound 2e led to significantly elevated FAO and reduced IMCL deposition in skeletal muscle. In ACC2 knockout mice, treatment with pharmacological doses of compound 2e did not reduce plasma triglyceride levels, whereas A-908292, a previously reported ACC2 inhibitor, caused a significant triglyceride reduction, showing that compound 2e was devoid of off-target triglyceride-lowering activity. Chronic treatment of db/db mice with compound 2e improved hyperglycemia but did not decrease plasma triglyceride levels. Additionally, compound 2e showed significant improvements of whole-body insulin resistance in the clamp study and insulin tolerance test. Collectively, compound 2e demonstrated a good safety profile and significant antidiabetic effects through inhibition of ACC2-dependent pathways. These findings provide further evidence that selective inhibition of ACC2 is an attractive strategy against insulin resistance and type 2 diabetes. SIGNIFICANCE STATEMENT: This study shows that pharmacological inhibition of acetyl-CoA carboxylase (ACC) 2 leads to significant improvements in whole-body glucose homeostasis, independently of off-target metabolic pathways and toxicity, which were observed in previously reported ACC2 inhibitors. These findings support the concept that ACC2-selective inhibitors will be a novel remedy for treatment of type 2 diabetes.


Assuntos
Acetil-CoA Carboxilase/antagonistas & inibidores , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Tipo 2/tratamento farmacológico , Hiperglicemia/prevenção & controle , Hipoglicemiantes/uso terapêutico , Resistência à Insulina , Acetil-CoA Carboxilase/genética , Animais , Glicemia/análise , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Tipo 2/sangue , Hipoglicemiantes/farmacocinética , Hipoglicemiantes/farmacologia , Hipoglicemiantes/toxicidade , Insulina/metabolismo , Camundongos Knockout , Músculo Esquelético/enzimologia , Pâncreas/efeitos dos fármacos , Pâncreas/metabolismo , Ratos Sprague-Dawley , Testes de Toxicidade , Triglicerídeos/sangue
16.
Lasers Med Sci ; 35(8): 1689-1694, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31925594

RESUMO

High-intensity resistance exercise (RE) increases oxidative stress leading to deleterious effects on muscle performance and recovery. The aim of this study was to assess the effect of applying low-level laser therapy (LLLT) prior to a RE session on muscle oxidative stress and to determine the possible influence of the dosimetric parameters. Female Wistar rats were assigned to non-LLLT (Ctr: non-exercised control; RNI: RE) or LLLT groups subjected to RE (radiant energy: 4 J, 8 J, and 12 J, respectively). RE consisted of four maximum load climbs. An 830-nm DMC Lase Photon III was used to irradiate three points in gastrocnemius muscles (two limbs) before exercise. Animals were euthanized after 60 min after the end of the exercise, and muscle tissue was removed for analysis of oxidative stress markers. All doses resulted in the prevention of increased lipoperoxidation; however, LLLT prevented protein oxidation only in rats that were pretreated with 8 J and 12 J of energy by LLLT. RE and LLLT did not change catalase activity. However, RE resulted in lower superoxide dismutase activity, and the opposite was observed in the LLLT group. These data indicate that LLLT prior to RE can prevent muscle oxidative stress. This study is the first to evaluate the impact of dosimetric LLLT parameters on the oxidative stress induced by RE, wherein both 8 J and 12 J of energy afforded significant protection.


Assuntos
Terapia com Luz de Baixa Intensidade , Músculo Esquelético/patologia , Estresse Oxidativo , Condicionamento Físico Animal , Treinamento de Resistência , Animais , Catalase/metabolismo , Feminino , Peroxidação de Lipídeos , Músculo Esquelético/enzimologia , Oxirredução , Ratos Wistar , Superóxido Dismutase/metabolismo
17.
Int J Sports Med ; 41(1): 36-43, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31747699

RESUMO

Subconcussive head impacts (SHI), defined as impacts to the cranium that do not result in concussion symptoms, are gaining traction as a major public health concern. The contribution of physiological factors such as physical exertion and muscle damage to SHI-dependent changes in neurological measures remains unknown. A prospective longitudinal study examined the association between physiological factors and SHI kinematics in 15 high school American football players over one season. Players wore a sensor-installed mouthguard for all practices and games, recording frequency and magnitude of all head impacts. Serum samples were collected at 12 time points (pre-season, pre- and post-game for five in-season games, and post-season) and were assessed for an isoenzyme of creatine kinase (CK-MM) primarily found in skeletal muscle. Physical exertion was estimated in the form of excess post-exercise oxygen consumption (EPOC) from heart rate data captured during the five games. Mixed-effect regression models indicated that head impact kinematics were significantly and positively associated with change in CK-MM but not EPOC. There was a significant and positive association between CK-MM and EPOC. These data suggest that when examining SHI, effects of skeletal muscle damage should be considered when using outcome measures that may have an interaction with muscle damage.


Assuntos
Futebol Americano/lesões , Cabeça/fisiopatologia , Músculo Esquelético/lesões , Esforço Físico/fisiologia , Adolescente , Fenômenos Biomecânicos , Concussão Encefálica/fisiopatologia , Creatina Quinase Forma MM/sangue , Futebol Americano/fisiologia , Humanos , Estudos Longitudinais , Masculino , Músculo Esquelético/enzimologia , Consumo de Oxigênio/fisiologia , Estudos Prospectivos , Estados Unidos
18.
J Clin Endocrinol Metab ; 105(3)2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31652310

RESUMO

CONTEXT: Obesity-related insulin resistance (OIR) is one of the main contributors to type 2 diabetes and other metabolic diseases. Protein kinases are implicated in insulin signaling and glucose metabolism. Molecular mechanisms underlying OIR involving global kinase activities remain incompletely understood. OBJECTIVE: To investigate abnormal kinase activity associated with OIR in human skeletal muscle. DESIGN: Utilization of stable isotopic labeling-based quantitative proteomics combined with affinity-based active enzyme probes to profile in vivo kinase activity in skeletal muscle from lean control (Lean) and OIR participants. PARTICIPANTS: A total of 16 nondiabetic adults, 8 Lean and 8 with OIR, underwent hyperinsulinemic-euglycemic clamp with muscle biopsy. RESULTS: We identified the first active kinome, comprising 54 active protein kinases, in human skeletal muscle. The activities of 23 kinases were different in OIR muscle compared with Lean muscle (11 hyper- and 12 hypo-active), while their protein abundance was the same between the 2 groups. The activities of multiple kinases involved in adenosine monophosphate-activated protein kinase (AMPK) and p38 signaling were lower in OIR compared with Lean. On the contrary, multiple kinases in the c-Jun N-terminal kinase (JNK) signaling pathway exhibited higher activity in OIR vs Lean. The kinase-substrate-prediction based on experimental data further confirmed a potential downregulation of insulin signaling (eg, inhibited phosphorylation of insulin receptor substrate-1 and AKT1/2). CONCLUSIONS: These findings provide a global view of the kinome activity in OIR and Lean muscle, pinpoint novel specific impairment in kinase activities in signaling pathways important for skeletal muscle insulin resistance, and may provide potential drug targets (ie, abnormal kinase activities) to prevent and/or reverse skeletal muscle insulin resistance in humans.


Assuntos
Resistência à Insulina , Músculo Esquelético/enzimologia , Obesidade/metabolismo , Proteínas Quinases/fisiologia , Proteoma , Proteínas Quinases Ativadas por AMP/fisiologia , Adulto , Feminino , Humanos , Masculino , Transdução de Sinais/fisiologia , Proteínas Quinases p38 Ativadas por Mitógeno/fisiologia
19.
J Ethnopharmacol ; 246: 112222, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31505213

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: The dried root of Paeonia lactiflora Pall. (Radix Paeoniae) has been traditionally used to treat various inflammatory diseases in many Asian countries. AIM OF THE STUDY: Cancer cachexia is a catabolic syndrome driven by inflammation and characterised by a loss of skeletal muscle. This study aimed to assess the effects of an ethanolic extract of Radix Paeoniae (RP) on cancer cachexia and elucidate its mechanism of action. MATERIAL AND METHODS: The anti-cachexic effect and mechanism of RP were examined in mouse models of cancer cachexia established in C57BL/6 mice by subcutaneously injecting Lewis lung carcinoma or MC38 colon carcinoma cells. Skeletal muscle tissues were analysed by RNAseq, real-time quantitative reverse transcription PCR, western blotting, and immunofluorescence microscopy. Megestrol acetate, which is recommended for the treatment of cachexia in cancer patients, was used as the comparator treatment in this study. RESULTS: In lung and colon cancer-bearing mice, RP significantly restored food intake and muscle mass, along with muscle function measured by grip strength and treadmill running time. In the skeletal muscle tissue of the cancer-bearing mice, RP suppressed NF-κB signalling and reduced inflammatory cytokines, including TNF-α, IL-6, and IL-1ß; it also down-regulated the muscle-specific E3 ubiquitin ligases MuRF1 and MAFbx. CONCLUSION: RP restored skeletal muscle function and mass in cancer-bearing mice by down-regulating the muscular NF-κB signalling pathway and muscle-specific E3 ubiquitin ligases. Our study indicates that RP is a potential candidate for development as a therapeutic agent against cancer cachexia.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Caquexia/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Paeonia/química , Extratos Vegetais/farmacologia , Raízes de Plantas/química , Ubiquitina-Proteína Ligases/metabolismo , Animais , Antineoplásicos Fitogênicos/química , Regulação da Expressão Gênica/efeitos dos fármacos , Camundongos , Músculo Esquelético/enzimologia , NF-kappa B , Fitoterapia , Extratos Vegetais/química , Transdução de Sinais , Ubiquitina-Proteína Ligases/química
20.
Artigo em Inglês | MEDLINE | ID: mdl-31465878

RESUMO

This study was conducted to characterise the muscle-specific gene expression, energy metabolism level and growth rates of Atlantic salmon Salmo salar L. reared under different photoperiod regimes. The effects of two photoperiod regimes - LD 16:8 (16 h light:8 h dark) and LD 24:0 (24 h light:0 h dark) over a period of 3 months (August to October) on growth, energy metabolism enzyme activities (cytochrome c oxidase, COX; lactate dehydrogenase, LDH; and aldolase) and the gene expression levels of myogenic regulatory factors (MRFs - MyoD1 paralogues (MyoD1a, MyoD1b, MyoD1c), Myf5, MyoG), myostatin paralogues (MSTN-1a, MSTN-1b, MSTN-2a) and the fast skeletal myosin heavy chain (MyHC) in the muscles of Atlantic salmon underyearling fry (0+) were investigated. The experiment was conducted in a fish hatchery with natural variations in water temperature. The results were compared with those obtained in salmon reared under the lighting conditions of a fish hatchery (HL, hatchery lighting). The results revealed that the fry reared under constant light (LD 24:0) grew faster and were bigger at the end of the experiment. Fishes reared within the photoperiod regime LD 16:8 had a lower growth rate. COX activity was lower in fish under the LD 16:8 regime compared with the LD 24:0 group. The LDH and aldolase enzyme activities were higher in the group with constant light in comparison to control in the beginning of September. The expression level for all of the genes studied variated during the duration of the experiment, and MyHC, MyoG, MyoD1a and Myf5 expression depended on the light regime as well. The more noticeable changes in gene expression occurred in October. The MyHC and MyoG mRNA levels increased, accompanied by MyD1c gene expression, in both groups that had additional lighting (LD 16:8 and LD24:0) at the beginning of October and were higher than the HL group. In the HL group, the elevation of MyHC and MyoG mRNA was gradual during October, but there was a sharp increase in Myf5 expression at the beginning of October. MyoD1 paralogues differently expressed during the experiment. The MyoD1a mRNA level was elevated at the end of October along with MyHC and MyoG expression, but MyoD1b and MyoD1c mRNA levels decreased along with Myf5 gene expression. The expression of MSTN paralogues were elevated with increases in MyHC and MRFs transcripts. These findings show that constant light has a positive effect on the growth rate of salmon, affecting the aerobic and anaerobic capacity in their muscles. The alterations in muscle-specific gene expression between the groups with different light indicated that the mechanisms for regulating muscle growth processes in fish depend on photoperiod duration.


Assuntos
Proteínas de Peixes/biossíntese , Regulação Enzimológica da Expressão Gênica/fisiologia , Proteínas Musculares/biossíntese , Músculo Esquelético/enzimologia , Salmo salar/metabolismo , Animais
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