Top PDF Glucose and lipid metabolism in human skeletal muscle

Glucose and lipid metabolism in human skeletal muscle

Glucose and lipid metabolism in human skeletal muscle

In the basal state NF-κB is bound to its inhibitory protein I κBα in the cytoplasm. IKKβ phosphorylates IκBα, which subsequently targets IκBα to proteosomal degradation. This results in nuclear translocation of NF κB and transcriptional activation of several proinflammatory genes. In human skeletal muscle, fatty acid-induced insulin resistance is closely associated with DAG accumulation and reduction of IκBα (Itani, Ruderman et al. 2002). Acute hyperlipidemia and HFD have also been reported to decrease I κBα levels in rodent skeletal muscle (Bhatt, Dube et al. 2006). Targetting the IKKβ/NF κB signaling pathway with high doses of salicylate, an inhibitor of IKKβ, prevents insulin resistance in skeletal muscle from rodents (Kim, Kim et al. 2001) and humans (Kim, Kim et al. 2001). IKKβ has also been shown to negatively affect insulin signaling by directly phosphorylating IRS-1 at serine residues (Gao, Hwang et al. 2002). On the other hand, muscle specific IKKβ knockdown mice are not protected against diet-induced insulin resistance (Rohl, Pasparakis et al. 2004). Pharmacological or genetic modification of NFκB does not protect C2C12 myotubes from insulin resistance induced by palmitate (Hommelberg, Plat et al. 2011). The pharmacological approaches, such as treatment with salicylate may actually be IKK-independent. It is known that salicylate is able to inhibit serine kinases, such as JNK and S6K, which interfere with insulin signaling through IRS-1 phosphorylation (Gao, Zuberi et al. 2003). Therefore, IKKβ/NF κB pathway may not play a central role in FFA-induced insulin resistance in skeletal muscle.
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A systems biology approach reveals a link between systemic cytokines and skeletal muscle energy metabolism in a rodent smoking model and human COPD

A systems biology approach reveals a link between systemic cytokines and skeletal muscle energy metabolism in a rodent smoking model and human COPD

Reverse transcription of 1 ug of isolated total RNA from whole-lung tissue (same RNA as were used for the microarray part) was performed using the Tetro cDNA synthesis kit (Bioline) with random hexamer primers fol- lowing the manufacturer’s instructions. The resulting cDNA was diluted 10-fold and 2.5 uL of this was used to perform qPCR in triplicate (25 uL reaction mixture vol- ume) using the Maxima SYBR green (Thermo Scientific) and 300 nM of primers according the manufacturer’s instructions. To adjust for variations in the cDNA synthe- sis, each gene was normalised to that of 18S ribosomal RNA and beta-actin mRNA, respectively. All reactions were run in singleplex on a StepOnePlus Real Time System (Applied Biosystems) at 95°C for 10 min, followed by 40 cy- cles at 95°C for 15 s and 60°C for 1 min. Two-fold dilution series were performed for all primer pairs to verify the lin- earity of the assay. In addition, dissociation curve analysis was performed after each PCR to check for unspecific sig- nals. Quantification was performed using the comparative cycle threshold (2 -ΔΔCt ) method.
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Irisin is expressed and produced by human muscle and adipose tissue in association with obesity and insulin resistance.

Irisin is expressed and produced by human muscle and adipose tissue in association with obesity and insulin resistance.

Irisin is a novel myokine, proteolytically processed from the product of the FNDC5 gene prior to being re- leased into the circulation (10). Irisin is regulated by per- oxisome proliferator-activated receptor- ␥ coactivator-1 (PGC1)- ␣ , and it has been proposed to mediate the ben- eficial effects of exercise on metabolism, inducing the browning of sc adipocytes and thermogenesis by increas- ing uncoupling protein 1 (UCP1) levels (10). In mice, irisin causes a significant increase in total body energy expen- diture and resistance to obesity-associated insulin resis- tance. In humans, contradictory effects of physical exer- cise on irisin production have been reported (11–13). Timmons et al (11), using gene expression arrays, detected an exercise-induced increase of FNDC5 mRNA in human muscle biopsies from old but not from young subjects. On the other hand, 2 recent studies found an association of FNDC5 gene expression and irisin levels with physical exercise and PGC1- ␣ mRNA level (12, 13). In human tissues, the distribution of FNDC5 expression was strongly increased in muscle in comparison with adipose tissue, similar to the findings described in mice (12). In fact, age-related muscle loss correlated to decreased cir- culating irisin concentration, muscle mass being the main predictor of this in humans (12). In this latter study, cir- culating irisin concentration levels were inversely corre- lated with adiponectin and positively correlated with body mass index (BMI), fasting glucose, and total cholesterol. Furthermore, after bariatric surgery-induced weight loss, circulating irisin levels as well as muscle FNDC5 gene expression were significantly down-regulated. According to these authors, these correlations may suggest a com- pensatory role for irisin in response to deterioration of insulin sensitivity and glucose/lipid metabolism (12).
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Genetic engineering of the skeletal muscle to counteract insulin resistance and obesity

Genetic engineering of the skeletal muscle to counteract insulin resistance and obesity

animals insulin sensitive during a HFD. Animals treated with the higher dose of AAVGck achieved a higher expression of Gck during the experiment, as evidenced by the northern blot. AAVGck-injected animals decreased their body weight gain by a 10% compared to HFD-fed control animals. During a high fat diet, the majority of weight gained is composed of lipids accumulating in different tissues. In agreement with the reduced body weight gain, AAVGck- treated animals presented a trend to show reduced epididymal fat pad mass and a reduction in hepatic lipid accumulation. Despite that no differences in lipid muscular accumulation were detected between groups, the fact that Cpt1 expression was increased in AAVGck-treated muscles indicates that fatty acid oxidation was probably enhanced in this tissue, providing an explanation to the observed reduction in the HFD-induced body weight gain. This is in agreement with the transgenic mouse model expressing Gck in the skeletal muscle that was literally protected against obesity (Otaegui et al., 2003). These mice overexpressed Ucp3 in the skeletal muscle, a protein suggested to increase fatty acid oxidation (Wang et al., 2003a). The fact that Ucp3 and Cpt1 are induced by the activation of AMPK, suggests a possible involvement of this protein in the activation of fatty acid metabolism by Gck (Li et al., 2007; Stoppani et al., 2002). Furthermore, as indicated in the insulin tolerance test, animals treated with the higher dose of AAVGck kept being as insulin sensitive as chow-fed control animals. Thus, increasing the dose of AAVGck resulted in a mild reduction in body weight gain, probably due to an increased fatty acid oxidation in the skeletal muscle, while preventing high fat diet-induced insulin resistance. This suggests that further increasing the dose of AAVGck might result in higher reductions in body weight gain.
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TítuloCentral ghrelin regulates peripheral lipid metabolism in a growth hormone independent fashion

TítuloCentral ghrelin regulates peripheral lipid metabolism in a growth hormone independent fashion

Central ghrelin effects are particularly intriguing in the case of AMPK, CPT1, and malonyl-CoA levels. Preceding studies demonstrated that peripheral and central administration of ghrelin to rats affects AMPK activity in a tissue-specific manner. AMPKα is activated in the brain and heart, whereas it is inhibited in liver and adipose tissue, and no effect is detected on skeletal muscle (17, 54, 60–63). Our data show for first time that chronic ghrelin treatment enhanced protein levels of AMPKα and pAMPKα. ACC activity was enhanced after central ghrelin infusion in liver and WAT, but the levels of its product, malonyl-CoA, were decreased in both tissues of wild-type Lewis rats. A reasonable explanation for this is that central ghrelin treatment increased the activities of FAS (liver and WAT) and MCD (only in WAT), leading to an increase of malonyl-CoA turnover. Malonyl-CoA acts as negative mediator of fatty acid oxidation by inhibiting CPT-1 and blocking entry of fatty acids into the mitochondria for β-oxidation (64). Interestingly, our results suggest that hepatic CPT1 is regulated in a GH-dependent manner because we observed that chronic infusion of ghrelin directly into the CNS decreased protein and activity levels of CPT1 only in the liver of wild-type Lewis rats and not in dwarf rats. This result suggests that the potential of central ghrelin to promote hepatic lipids storage is higher in a GH-dependent- (favoring lipid deposition and decreasing lipid mobilization) than in a GH-independent manner (favoring only lipid deposition). Contrary to what happens in liver, central ghrelin infusion increased CPT1 protein and activity levels in WAT, independent of GH levels. Nevertheless, activation of the central ghrelin system may increase lipid oxidation in WAT, and our data indicate that fat mass and fat storage enzymes were also stimulated by ghrelin. Thereby, our data suggest that the enhanced β-oxidation in WAT after central ghrelin infusion might be a compensatory mechanism and is a GH-independent effect.
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Intestinal fructose and glucose metabolism in health and disease

Intestinal fructose and glucose metabolism in health and disease

Fructose may cause insulin resistance by accumulation of triglycerides in the liver. There are two metabolic pathways to increased hepatic lipid content, i.e., lipogenesis and/or reduced mitochondrial fatty acid oxidation. Hepatic fructolysis leads to increased gluconeogenic sources resulting in elevated rates of lipogenesis [16,45,46]. Hepatic accumulation of toxic intermediary lipid metabolites, such as diacylglycerol (DAG) results in PKC ε activation that impairs hepatic insulin signaling through phosphorylation of serine residues on the insulin receptor substrate 1 and 2 (IRS1/2). When hepatic insulin signaling is impaired, gluconeogenesis and glycogenolysis are unleashed, contributing to hyperglycemia and hyperinsulinemia. Under these circumstances, hepatic lipid synthesis is enhanced due to hyperinsulinemia [241,242]. Likewise, reduced fatty acid oxidation leads to hepatic triglycerides accumulation. Of note, Ohashi et al. demonstrated that excessive amounts of fructose consumption lead to epigenetic modifications, such as DNA hypermethylation of promoter regions of peroxisome proliferator-activated receptor alpha (PPAR α ) and carnitine palmitoyl transferase 1A (CPT1A) that results in lower amounts of mRNA levels [243]. Hepatic triglyceride accumulation results in augmented secretion of very low-density lipoprotein (VLDL) leading to increased lipid uptake in skeletal muscle and peripheral tissues. Similarly to what happens in the liver, intramyocellular lipid accumulation (particularly DAG) activates the PKC θ isoform that phosphorylates and inactivates IRS1 resulting in impaired insulin-stimulated glucose uptake, contributing to hyperglycemia, increased delivery of glucose to the liver, and hyperinsulinemia [241,242].
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Altered lipid metabolism in a Drosophila model of Friedreich’s ataxia

Altered lipid metabolism in a Drosophila model of Friedreich’s ataxia

The FA accumulation observed in the Drosophila FRDA model is in good agreement with the lipid inclusions found previously in the cardiac muscle of FRDA conditional mouse models (33) and with the increased intracellular lipid content present in the striated muscle fibers and Schwann cells of inherited a-tocopherol deficiency patients (21), a disease that appears to be clinically indistinguishable from FRDA. Moreover, up to 40% of FRDA patients manifest different glucose metabolism problems (53) such as diabetes or insulin resistance, and remarkably type 2 diabetes patients also present an altered lipid status attributable to a mitochon- drial dysfunction (54,55). However, the link between increased lipid amounts and FRDA is not completely clear. On the one hand, depletion of frataxin generates different scenarios that can lead to the inhibition of mitochondrial b-oxidation. For example, mitochondrial respiration defects induce a reduction of NAD + /NADH ratios compromising the b-oxidation pathway (22,56). Alternatively, impairment of aconitase activity increases citrate levels (57), and citrate is an allosteric activator of malonyl-CoA production, which in turn is a potent inhibitor of the mitochondrial b-oxidation (reviewed in 58). Furthermore, downregulation of peroxisome proliferator-activated receptor gamma (PPARg) pathway has been observed in FRDA mice models, suggesting a reduction of lipid catabolism (59). Moreover, on the other hand, frataxin deficiency has been suggested to increase lipogenesis via hyperactivation of mitochondrial acyl-CoA thioesterase (60) or upregulating the expression of the sterol-responsive element-binding protein 1 (Srebp1) (59). Thus, derangement of lipid homeostasis in FRDA could be produced by either blocking the main degradation pathway of FAs or increasing their synthesis. In addition, lipid imbalance could be a critical event in FRDA progression since lipid metabolism is the main fuel source of the cell.
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Molecular regulators of glucose and lipid metabolism in skeletal muscle

Molecular regulators of glucose and lipid metabolism in skeletal muscle

The 5’-nucleotidases are a family of enzymes that catalyze the dephosphorylation of nucleoside monophosphates and regulate cellular nucleoside and nucleotide levels (Bianchi and Spychala, 2003). The 5’-nucleotidase was first studied in vitro using a semi-purified enzymes extracted from rat and guinea pig skeletal muscle (Cozzani et al., 1969). There are various biochemical pathways that govern purine and pyrimidine nucleotide metabolism. These pathways maintain the levels of purine and pyrimidine nucleotide triphosphates vital to support various cellular processes. 5’-nucleotidases catabolize nucleoside monophosphates and change their abundance. Therefore they are components of cellular energy homeostasis. Besides maintaining balanced ribo and deoxyribonucleotide pools, nucleotidase activities are likely to regulate the activation of nucleoside analogues, a class of anti-cancer and anti-viral agents that rely on the nucleoside kinases for phosphorylation to convert to their phosphorylated active forms (Hunsucker et al., 2005). Early studies on 5’-nucleotidases have revealed a membrane bound ecto-enzyme and soluble form cytosolic enzymes. In humans, seven 5’- nucleotidases have been isolated and characterized that vary in subcellular localization. Out of the seven known 5’-nucleotidases, five are of the soluble form and they are localized to cytosol, one is localized to the mitochondrial matrix (NT5M) and one is bound to the extracellular portion of the plasma membrane (the ecto 5’-nucleotidase or E5’N) (Hunsucker et al., 2005). These enzymes have similar functions in that they hydrolyze 5’ nucleoside monophosphates, but they differ in their specificity towards their substrate. Some of these enzymes are ubiquitously distributed and some are tissue- specific. Differences in subcellular localization, specificity towards their substrate and tissue specific distribution allow regulation of nucleotide pools to meet the energy balance and cellular homeostasis. This thesis will focus on two of the soluble 5’- nucleotidases enzymes, namely NT5C1A and NT5C2.
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Protective effects of epoxypukalide on pancreatic b-cells and glucose metabolism in STZ-induced diabetic mice

Protective effects of epoxypukalide on pancreatic b-cells and glucose metabolism in STZ-induced diabetic mice

b -cell mass can be increased by augmented proliferation and/ or decreased b-cell death. To understand how b-cell number was increased in Epoxy treated mice we quantified both. b-cell death was detected by TUNEL staining, and proliferation by measur- ing BrdU incorporation in insulin-positive cells. Our results showed a 50% decrease in b-cell death in Epoxy treated b-cells (Fig. 3A-B), and a 2-fold increase in b-cell proliferation (Fig. 3C-D). Interestingly, this proliferative effect is specific on pancreatic b -cells, since other endocrine cells as a -cells showed similar proliferation in both conditions (0.04 § 0.03 % vs. 0.09 § 0.05 %; p D 0.49). These results support the view that Epoxy is an inhibitor of b -cell apoptosis under STZ toxicity, and it enhances b -cell proliferation in vivo.
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The prevalence and clinical characteristics of glucose metabolism disorders in patients with liver cirrhosis  A prospective study

The prevalence and clinical characteristics of glucose metabolism disorders in patients with liver cirrhosis A prospective study

Aims. To define the prevalence and clinical characteristics of glucose metabolism disorders (GMD) in pa- tients with compensated liver cirrhosis (LC). Material and methods. Fasting plasma glucose (FPG) levels were measured to 130 patients with clinically stable LC. Oral glucose tolerance tests (OGTT) and fasting plasma insulin determinations were performed to patients with normal FPG. Insulin resistance (IR) was calculated with HOMA2-IR index. GMD were classified according to FPG and OGTT tests results and to the chronologic relation between diagnosis of diabetes mellitus (DM) and LC as follows: type-2 DM (T2DM), hepatogenous diabetes (HD) and impaired glucose tolerance. Patients from all groups were compared. Results. The prevalence of GMD were as follows: T2DM in 25 patients (19.2%, 95% CI 12.5-25.9), HD in 28 (21.5%, 95% CI 14.5-28.5) and IGT in 36 (38.5%, 95% CI 30.1-46.7). The total of patients with GMD was 79.2% (95% CI 72.3-86.1). In 41% of cases GMD were subclinical and 48.7% of patients had IR. Patients with T2DM had a higher number of variables with significant differences compared with the other groups (more mar- ked compared to the patients without GMD). The only differences between the patients with T2DM and HD were hypercreatininemia: 1.14 ± 0.53 vs. 0.84 ± 0.22 mg/dL (p = 0.005) and family history of DM: 8 (32%) vs. 2 (7%) (p = 0.02). Conclusion. Almost 80% of patients with compensated LC had GMD. Half of them were subclinical. The patients with T2DM had marked clinical differences compared to patients from the other groups, particularly renal impairment.
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Regional differences in prostaglandin E₂ metabolism in human colorectal cancer liver metastases

Regional differences in prostaglandin E₂ metabolism in human colorectal cancer liver metastases

and metastasis [6]. Recently, PGE 2 has been implicated in promotion of EMT in vitro [8]. PG G/H synthase (also known as cyclooxygenase [COX]) controls the rate-limiting step in PGE 2 synthesis, upstream of PGE synthases [6]. There are two COX isoforms; the consti- tutive isoform COX-1 and the inducible isoform COX-2, which is up-regulated in CRC and is a putative target for anti-CRC therapy [9,10]. Nicotinamide adenine di- nucleotide (NAD+)-linked 15-hydroxyprostaglandin de- hydrogenase (15-PGDH) controls the rate-limiting step in PGE 2 catabolism by conversion of PGE 2 to 15-keto- PGE 2 coupled to the reduction of NAD+ to NADH [11]. Initial studies suggested that 15-PGDH expression is reduced in bladder cancer, lung cancer and CRC compared with paired normal tissue and has tumour suppressor properties [12]. However, subsequent reports have highlighted elevated 15-PGDH expression in breast and ovarian cancer [12]. Moreover, there are conflicting data on 15-PGDH expression in gastric cancer [12]. Het- erogeneity of 15-PGDH expression in human cancers may reflect tissue-specific differences in regulatory pathways upstream of 15-PGDH [12], but may also be related to sampling variation secondary to intra-tumoral genetic and micro-environmental influences on 15- PGDH expression [13,14].
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Andrographolide attenuates skeletal muscle dystrophy in mdx mice and increases efficiency of cell therapy by reducing fibrosis

Andrographolide attenuates skeletal muscle dystrophy in mdx mice and increases efficiency of cell therapy by reducing fibrosis

Single myofiber isolation and satellite cell grafting Single myofibers were isolated essentially as described previously [6,36]. Briefly, extensor digitorum longus (EDL) and soleus muscles from six-week-old C57-BL10 mice were dissected and digested in 0.2% (w/v) collagenase type 1 (Sigma, St. Louis, MO, USA) in DMEM (Gibco, Grand Island, NY, USA) with 4 mM L-glutamine (Sigma, St. Louis, MO, USA) and 1% penicillin and streptomycin solu- tion (Sigma, St. Louis, MO, USA) for 90 minutes in a 37°C water bath. Satellite cells were separated from the myo- fibers by physical trituration using the method of Collins et al. [36]. The isolated intact fibers were suspended in 10 ml of complete medium and triturated with a 19 G needle mounted on a 1 ml syringe. The suspension was sequen- tially passed through a 70-μm and 40-μm cell sieve (BD Biosciences, San Jose, CA, USA) to remove debris. The satellite cell suspension was centrifuged for 15 minutes at 450 × g. The pellet was resuspended in physiologic serum (0.9% NaCl). An aliquot was stained with 1 μg/ml Hoechst and 1 μg/ml cholera toxin subunit B conjugated to Alexa Fluor 488 (Invitrogen, Carlsbad, CA, USA) for five mi- nutes, washed with PBS and incubated with trypan blue. Cells were counted using a hemocytometer. Double- stained cells that exclude trypan blue were counted as vi- able cells and the concentration of cells was adjusted to 25 cells/μl. To confirm the purity of the isolated satellite cells, an aliquot was seeded onto Matrigel (1 mg/ml) (Sigma, St. Louis, MO, USA) and cultured overnight in complete medium for 18 hours before immunocytochemistry for myogenic markers. For grafting, 500 satellite cells were grafted into both TA muscles of seven-month-old mdx mice in a C57-BL10 background under anesthesia using an 8-mm 30 G needle under microscopic observation.The number of dystrophin positive fibers was determined as de- scribed previously [6].
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Phosphoethanolamine transferases in Haemophilus ducreyi modify lipid A and contribute to human defensin resistance

Phosphoethanolamine transferases in Haemophilus ducreyi modify lipid A and contribute to human defensin resistance

The Sap transporter is an influx pump and belongs to the family of oligopeptide (Opp)–dipeptide (Dpp) peptide and metal ion–uptake ATP binding cassette (ABC) transporters (136-138). Structurally, the Sap transporter has five main components: SapA, SapB, SapC, SapD, and SapF (Figure 1A). SapB and SapC are permease proteins found in the inner membrane and form a pore. SapD and SapF are ATPase subunits that use the energy from converting ATP to ADP to power the influx pump. SapA is a periplasmic binding protein that binds to specific peptides and shuttles them through SapBC by the energy provided from SapDF (136, 138). In Haemophilus influenzae, the Sap transporter has been shown to play a role in cellular homeostasis by conferring uptake of heme, and SapD specifically is involved in potassium uptake (138, 139). The Sap transporter also confers resistance to both LL-37 and the β-defensin HBD-3 by directly binding to the APs and shuttling them into the cytoplasm before they can attach to the inner membrane, the lethal target for APs (138, 140, 141). Once inside the cytoplasm, the APs are degraded by cytoplasmic peptidases (137). In addition to H. influenzae, the Sap transporter has been found to confer resistance to APs in Salmonella enterica, Erwinia chrysanthemi, and Proteus mirabilis (136, 142, 143).
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Glypican 1 regulates myoblast response to HGF via Met in a lipid raft dependent mechanism: Effect on migration of skeletal muscle precursor cells

Glypican 1 regulates myoblast response to HGF via Met in a lipid raft dependent mechanism: Effect on migration of skeletal muscle precursor cells

Hepatocyte growth factor affinity labeling and binding assay Carrier-free HFG was radiolabeled with Na 125 I using the chloramine T method as previously described for FGF-2 [38]. The biological activity of the radiolabeled HGF was determined by its ability to induce phosphorylation of ERK1/2 compared to unlabeled HGF as described above. The binding of [ 125 I]HGF to cell surfaces was performed as described previously with some modifications [46]. Briefly, subconfluent myoblasts were incubated for 2 hours at 4°C in DMEM containing 0.2% BSA, 25 mM 2-[4-(2- hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES), pH 7.4, and 10 ng/ml [ 125 I]HGF. To determine nonspecific binding, parallel cultures were incubated under the same conditions with the addition of a 200-fold excess of un- labeled HGF. After several washes in binding buffer and once with phosphate-buffered saline to remove unbound ligand, the cells were sequentially washed twice with 2 M NaCl in 20 mM HEPES, pH 7.4, for 5 minutes (low affinity binding) and twice with 2 M NaCl in 20 mM NaAc, pH 4.0, for 5 minutes (high-affinity binding) [47-49]. The cells were extracted, and the protein content was deter- mined as indicated below. The amount of radioactivity present in the low- and high-affinity washes and cell ex- tracts was determined using a γ scintillation counter. The counts per minute (cpm) values were corrected for the protein content in the cell extracts.
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Greater basal skeletal muscle AMPKalpha phosphorylation in men than in women: associations with anaerobic performance

Greater basal skeletal muscle AMPKalpha phosphorylation in men than in women: associations with anaerobic performance

In agreement with previous studies, men had a higher percent of type IIa fibres and MHC IIa (Richter & Ruderman, 2009; Roepstorff et al., 2006). Greater basal AMPK α Thr 172 phosphoryl- ation has been reported in type IIa muscle fibres from the vastus lateralis in five men using immuno- fluorescence (Lee-Young, Canny, Myers, & McCo- nell, 2009). Thus, in agreement with the immunohistochemistry-based study of Lee-Young et al. (2009), men had greater basal Thr 172 AMPK phosphorylation than women, partly because men had a higher proportion of type IIa fibres. However, when only men were included in our statistical analy- sis, basal AMPK phosphorylation was positively associated with MHC I, which is reasonable, due to the fact that muscle AMPK signalling governs fibre switching to a more oxidative phenotype, in conjunc- tion with PGC-1 α , PPAR δ , and SIRT1, among other transcription factors (Steinberg & Jorgensen, 2007). In accordance, pharmacologically activation of AMPK has been associated with a shift from fibre type b to IIa/x in rodents (Narkar et al., 2008). This view is further supported by the fact that caloric restriction increases basal Thr 172 AMPK α phos- phorylation and fast to slow muscle fibre type tran- sitions potentially acting through SIRT1 and PGC- 1 α (Speakman & Mitchell, 2011). The observed linear positive association between Thr 172 AMPK α phosphorylation and MHC I in the present investi- gation may seem at odds with the findings of Lee- Young et al. (2009). This discrepancy may be due to methodological differences (5 men and immuno- histochemistry in Lee-Young et al. study and 25 men and Western blot in the present study). More- over, Mortensen et al. (2009) observed significant between-sex differences in AMPK γ 3 mRNA, protein levels, and activity after adjustment for MHC mRNA proportions, indicating that sex differ- ences in AMPK γ 3 expression and activity are, at least in part, independent of skeletal muscle fibre type (Mortensen et al., 2009). It should be highlighted that most AMPK heterotrimers contain the γ 3 isoform in human skeletal muscle, implying that the increased AMPK γ 3 activity reported by this investi- gation should account for most of the AMPK α activity.
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Role of proteoglycans in the regulation of the skeletal muscle fibrotic response

Role of proteoglycans in the regulation of the skeletal muscle fibrotic response

The fact that decorin binds CTGF and TGF- b at dif- ferent decorin LRR domains, modulating their biologi- cal activity, opens a new avenue of research, with unexpected results. CTGF is able to interact with receptors located on the cell surface, including inte- grins [88], LRP-1 [97], and HSPGs [49,50]. In addition, CTGF binds TGF-b, stimulating its biological activity [84]. The role of CTGF in regulating the complex interactions of TGF- b signaling is poorly understood. We speculate that decorin could be a regulatory pro- tein for both profibrotic factors, through the interac- tion with one of the common receptors, LRP-1 [51,74 – 76,86]. b -Glycan and/or other HSPGs could also form part of this complex of common elements. As men- tioned, b -glycan binds TGF- b via its core protein, but also can bind CTGF via its heparan sulfate GAG chains [49], and at the same time, can bind to the hep- aran sulfate-binding domains of LRP-1 [98] (Fig. 1). These complex and interesting interactions among these two profibrotic growth factors, together with sev- eral common elements, could be essential for revealing critical steps in signaling followed by triggering of fibrotic responses, and could eventually lead to the development of specific inhibitors against these profib- rotic factors with potential use in therapy.
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TítuloTrophic relationships between Saccharomyces cerevisiae and Lactobacillus plantarum and their metabolism of glucose and citrate

TítuloTrophic relationships between Saccharomyces cerevisiae and Lactobacillus plantarum and their metabolism of glucose and citrate

Vol 57, No 4APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Apr 1991, p 1046 1051 0099 2240/91/041046 06$02 00/0 Copyright ? 1991, American Society for Microbiology Trophic Relationships between Saccharomyces[.]

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Post-exercise effects of graduated compression garment use on skeletal muscle recovery and delayed onset muscle soreness: a systematic review

Post-exercise effects of graduated compression garment use on skeletal muscle recovery and delayed onset muscle soreness: a systematic review

The use of graduated compression garments (GCGs) has shown to be efficient in the prevention and treatment of lymphatic and venous diseases (Kelechi, Johnson & WOCN Society, 2012; Nelson & Bell-Syer, 2012), pathologies which affect the population in general due to prolonged standing or sitting positions (Fernandes, Rodrigues & Vianna, 2011; França & Tavares, 2003). The use of these compression accessories aims to reduce inflammatory mediators, promote drainage of metabolites, increase venous return and decrease edema (swelling), favoring the transport of oxygen to the skin and subcutaneous tissue in order to accelerate the healing of venous ulcers (Partsch, Flour & Smith, 2008; Figueiredo, Filho & Cabral, 2004). The advantages derived from the use of GCGs have created a demand for the industry to improve the quality and increase the quantity of GCGs (Gill, Beaven & Cook, 2006) in order to meet the demands ranging from medical
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Lipid biomarkers in Lake Enol (Asturias, Northern Spain): Coupled natural and human induced environmental history

Lipid biomarkers in Lake Enol (Asturias, Northern Spain): Coupled natural and human induced environmental history

1695 AD to the water body, although the uppermost cm revealed a predominance of organic matter (üM) derived from algae, as the most abundant alkane was C 17• Three units revealing differ[r]

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Human Choroid Plexus Papilloma Cells Efficiently Transport Glucose and Vitamin C

Human Choroid Plexus Papilloma Cells Efficiently Transport Glucose and Vitamin C

Magnetic resonance image (MRI) revealed a lobular and irregular mass located at the left lateral ventricle that distorted the shape of its horn in a 22-year-old patient, which was subsequently diagnosed as HCPP (Fig. 2a). Resected tissue sections were stained using Gallego’s stain to analyze tumor tissue architecture and cell morphology (Fig. 2b and c). As expected, the HCPP showed an extensive papillary growth (Fig. 2b), with multiple papillae covered by single layer of tumor epithelial cells protruding to the center of the lateral ventricle (Fig. 2c). Immunofluorescence anal- ysis of TTR, (Fig. 1d–f) revealed its cytoplasmic localization within tumor epithelial cells (Fig. 2f). In parallel, analysis of GLUT1 – 5, SVCT1 and SVCT2 expression in HCPP tissues by immunohistochemistry revealed positive immunostaining for only GLUT1 and SVCT2 (data not shown). To gain insight into the cellular distribution of GLUT1 and SVCT2 in HCPP tissues, expression of these proteins was analyzed using immunohistochemistry (Fig. 2g–i). Whereas GLUT1 was preferentially localized to the plasma membrane and the cytoplasm of HCPP cells (Fig. 2g), SVCT2 was primarily observed in the cytoplasm of HCPP cells (Fig. 2h). Co- localization of both proteins was evident (Fig. 2i, yellow immunostaining). These results indicated that HCPP cells have the potential to incorporate and metabolize glucose as well as AA and DHA.
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