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Sample records for modulate protein metabolism

  1. Insulin Stimulates S100B Secretion and These Proteins Antagonistically Modulate Brain Glucose Metabolism.

    PubMed

    Wartchow, Krista Minéia; Tramontina, Ana Carolina; de Souza, Daniela F; Biasibetti, Regina; Bobermin, Larissa D; Gonçalves, Carlos-Alberto

    2016-06-01

    Brain metabolism is highly dependent on glucose, which is derived from the blood circulation and metabolized by the astrocytes and other neural cells via several pathways. Glucose uptake in the brain does not involve insulin-dependent glucose transporters; however, this hormone affects the glucose influx to the brain. Changes in cerebrospinal fluid levels of S100B (an astrocyte-derived protein) have been associated with alterations in glucose metabolism; however, there is no evidence whether insulin modulates glucose metabolism and S100B secretion. Herein, we investigated the effect of S100B on glucose metabolism, measuring D-(3)H-glucose incorporation in two preparations, C6 glioma cells and acute hippocampal slices, and we also investigated the effect of insulin on S100B secretion. Our results showed that: (a) S100B at physiological levels decreases glucose uptake, through the multiligand receptor RAGE and mitogen-activated protein kinase/ERK signaling, and (b) insulin stimulated S100B secretion via PI3K signaling. Our findings indicate the existence of insulin-S100B modulation of glucose utilization in the brain tissue, and may improve our understanding of glucose metabolism in several conditions such as ketosis, streptozotocin-induced dementia and pharmacological exposure to antipsychotics, situations that lead to changes in insulin signaling and extracellular levels of S100B. PMID:26875731

  2. Dengue Virus NS1 Protein Modulates Cellular Energy Metabolism by Increasing Glyceraldehyde-3-Phosphate Dehydrogenase Activity

    PubMed Central

    Allonso, Diego; Andrade, Iamara S.; Conde, Jonas N.; Coelho, Diego R.; Rocha, Daniele C. P.; da Silva, Manuela L.; Ventura, Gustavo T.

    2015-01-01

    ABSTRACT Dengue is one of the main public health concerns worldwide. Recent estimates indicate that over 390 million people are infected annually with the dengue virus (DENV), resulting in thousands of deaths. Among the DENV nonstructural proteins, the NS1 protein is the only one whose function during replication is still unknown. NS1 is a 46- to 55-kDa glycoprotein commonly found as both a membrane-associated homodimer and a soluble hexameric barrel-shaped lipoprotein. Despite its role in the pathogenic process, NS1 is essential for proper RNA accumulation and virus production. In the present study, we identified that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) interacts with intracellular NS1. Molecular docking revealed that this interaction occurs through the hydrophobic protrusion of NS1 and the hydrophobic residues located at the opposite side of the catalytic site. Moreover, addition of purified recombinant NS1 enhanced the glycolytic activity of GAPDH in vitro. Interestingly, we observed that DENV infection promoted the relocalization of GAPDH to the perinuclear region, where NS1 is commonly found. Both DENV infection and expression of NS1 itself resulted in increased GAPDH activity. Our findings indicate that the NS1 protein acts to increase glycolytic flux and, consequently, energy production, which is consistent with the recent finding that DENV induces and requires glycolysis for proper replication. This is the first report to propose that NS1 is an important modulator of cellular energy metabolism. The data presented here provide new insights that may be useful for further drug design and the development of alternative antiviral therapies against DENV. IMPORTANCE Dengue represents a serious public health problem worldwide and is caused by infection with dengue virus (DENV). Estimates indicate that half of the global population is at risk of infection, with almost 400 million cases occurring per year. The NS1 glycoprotein is found in both the

  3. Dynamic Evolution of Nitric Oxide Detoxifying Flavohemoglobins, a Family of Single-Protein Metabolic Modules in Bacteria and Eukaryotes.

    PubMed

    Wisecaver, Jennifer H; Alexander, William G; King, Sean B; Hittinger, Chris Todd; Rokas, Antonis

    2016-08-01

    Due to their functional independence, proteins that comprise standalone metabolic units, which we name single-protein metabolic modules, may be particularly prone to gene duplication (GD) and horizontal gene transfer (HGT). Flavohemoglobins (flavoHbs) are prime examples of single-protein metabolic modules, detoxifying nitric oxide (NO), a ubiquitous toxin whose antimicrobial properties many life forms exploit, to nitrate, a common source of nitrogen for organisms. FlavoHbs appear widespread in bacteria and have been identified in a handful of microbial eukaryotes, but how the distribution of this ecologically and biomedically important protein family evolved remains unknown. Reconstruction of the evolutionary history of 3,318 flavoHb protein sequences covering the family's known diversity showed evidence of recurrent HGT at multiple evolutionary scales including intrabacterial HGT, as well as HGT from bacteria to eukaryotes. One of the most striking examples of HGT is the acquisition of a flavoHb by the dandruff- and eczema-causing fungus Malassezia from Corynebacterium Actinobacteria, a transfer that growth experiments show is capable of mediating NO resistance in fungi. Other flavoHbs arose via GD; for example, many filamentous fungi possess two flavoHbs that are differentially targeted to the cytosol and mitochondria, likely conferring protection against external and internal sources of NO, respectively. Because single-protein metabolic modules such as flavoHb function independently, readily undergo GD and HGT, and are frequently involved in organismal defense and competition, we suggest that they represent "plug-and-play" proteins for ecological arms races. PMID:27189567

  4. Redox modulation of cellular metabolism through targeted degradation of signaling proteins by the proteasome

    SciTech Connect

    Squier, Thomas C.

    2006-02-01

    Under conditions of oxidative stress, the 20S proteasome plays a critical role in maintaining cellular homeostasis through the selective degradation of oxidized and damaged proteins. This adaptive stress response is distinct from ubiquitin-dependent pathways in that oxidized proteins are recognized and degraded in an ATP-independent mechanism, which can involve the molecular chaperone Hsp90. Like the regulatory complexes 19S and 11S REG, Hsp90 tightly associates with the 20S proteasome to mediate the recognition of aberrant proteins for degradation. In the case of the calcium signaling protein calmodulin, proteasomal degradation results from the oxidation of a single surface exposed methionine (i.e., Met145); oxidation of the other eight methionines has a minimal effect on the recognition and degradation of calmodulin by the proteasome. Since cellular concentrations of calmodulin are limiting, the targeted degradation of this critical signaling protein under conditions of oxidative stress will result in the downregulation of cellular metabolism, serving as a feedback regulation to diminish the generation of reactive oxygen species. The targeted degradation of critical signaling proteins, such as calmodulin, can function as sensors of oxidative stress to downregulate global rates of metabolism and enhance cellular survival.

  5. AMP-activated Protein Kinase Signaling Activation by Resveratrol Modulates Amyloid-β Peptide Metabolism*

    PubMed Central

    Vingtdeux, Valérie; Giliberto, Luca; Zhao, Haitian; Chandakkar, Pallavi; Wu, Qingli; Simon, James E.; Janle, Elsa M.; Lobo, Jessica; Ferruzzi, Mario G.; Davies, Peter; Marambaud, Philippe

    2010-01-01

    Alzheimer disease is an age-related neurodegenerative disorder characterized by amyloid-β (Aβ) peptide deposition into cerebral amyloid plaques. The natural polyphenol resveratrol promotes anti-aging pathways via the activation of several metabolic sensors, including the AMP-activated protein kinase (AMPK). Resveratrol also lowers Aβ levels in cell lines; however, the underlying mechanism responsible for this effect is largely unknown. Moreover, the bioavailability of resveratrol in the brain remains uncertain. Here we show that AMPK signaling controls Aβ metabolism and mediates the anti-amyloidogenic effect of resveratrol in non-neuronal and neuronal cells, including in mouse primary neurons. Resveratrol increased cytosolic calcium levels and promoted AMPK activation by the calcium/calmodulin-dependent protein kinase kinase-β. Direct pharmacological and genetic activation of AMPK lowered extracellular Aβ accumulation, whereas AMPK inhibition reduced the effect of resveratrol on Aβ levels. Furthermore, resveratrol inhibited the AMPK target mTOR (mammalian target of rapamycin) to trigger autophagy and lysosomal degradation of Aβ. Finally, orally administered resveratrol in mice was detected in the brain where it activated AMPK and reduced cerebral Aβ levels and deposition in the cortex. These data suggest that resveratrol and pharmacological activation of AMPK have therapeutic potential against Alzheimer disease. PMID:20080969

  6. Redox Modulation of Cellular Signaling and Metabolism Through Reversible Oxidation of Methionine Sensors in Calcium Regulatory Proteins

    SciTech Connect

    Bigelow, Diana J.; Squier, Thomas C.

    2005-01-17

    Adaptive responses associated with environmental stressors are critical to cell survival. These involve the modulation of central signaling protein functions through site-specific and enzymatically reversible oxidative modifications of methionines to coordinate cellular metabolism, energy utilization, and calcium signaling. Under conditions when cellular redox and antioxidant defenses are overwhelmed, the selective oxidation of critical methionines within selected protein sensors functions to down-regulate energy metabolism and the further generation of reactive oxygen species (ROS). Mechanistically, these functional changes within protein sensors take advantage of the helix-breaking character of methionine sulfoxide. Thus, depending on either the ecological niche of the organism or the cellular milieu of different organ systems, cellular metabolism can be fine-tuned to maintain optimal function in the face of variable amounts of collateral oxidative damage. The sensitivity of several calcium regulatory proteins to oxidative modification provides cellular sensors that link oxidative stress to cellular response and recovery. Calmodulin (CaM) is one such critical calcium regulatory protein, which is functionally sensitive to methionine oxidation. Helix destabilization resulting from the oxidation of either Met{sup 144} or Met{sup 145} results in the nonproductive association between CaM and target proteins. The ability of oxidized CaM to stabilize its target proteins in an inhibited state with an affinity similar to that of native (unoxidized) CaM permits this central regulatory protein to function as a cellular rheostat that down-regulates energy metabolism in response to oxidative stress. Likewise, oxidation of a methionine within a critical switch region of the regulatory protein phospholamban is expected to destabilize the phosphorylationdependent helix formation necessary for the release of enzyme inhibition, resulting in a down-regulation of the Ca-ATPase in

  7. Rice bran proteins and their hydrolysates modulate cholesterol metabolism in mice on hypercholesterolemic diets.

    PubMed

    Zhang, Huijuan; Wang, Jing; Liu, Yingli; Gong, Lingxiao; Sun, Baoguo

    2016-06-15

    The hypolipidemic properties of defatted rice bran protein (DRBP), fresh rice bran protein (FRBP), DRBP hydrolysates (DRBPH), and FRBP hydrolysates (FRBPH) were determined in mice on high fat diets for four weeks. Very low-density lipoprotein cholesterol (VLDL-C), low-density lipoprotein cholesterol (LDL-C) contents, and the hepatic total cholesterol content were reduced while fecal total cholesterol and total bile acid (TBA) contents were increased in the FRBPH diet group. The expression levels of hepatic genes for cholesterol biosynthesis HMG-CoAR and SREBP-2 were lowest in the FRBPH diet group. The mRNA level of HMG-CoAR was significantly positively correlated with the hepatic TG content (r = 0.82, P < 0.05). The mRNA levels of genes related to bile acid biosynthesis and cholesterol efflux, CYP7A1, ABCA1, and PPARγ were up-regulated in all test groups. The results suggest that FRBPH regulates cholesterol metabolism in mice fed the high fat and cholesterol diet by increasing fecal steroid excretion and expression levels of genes related to bile acid synthesis and cholesterol efflux, and the down-regulation of the expression levels of genes related to cholesterol biosynthesis. PMID:27216972

  8. Physical exercise and a leucine-rich diet modulate the muscle protein metabolism in Walker tumor-bearing rats.

    PubMed

    Salomão, Emilianne M; Toneto, Aline T; Silva, Gisele O; Gomes-Marcondes, Maria Cristina C

    2010-01-01

    Leucine-supplemented diet can recover lean body mass and preserve muscle protein mass. Additionally, physical exercise can be an excellent alternative to improve the rehabilitation of cancer patients. Knowing these facts, we examined the effects of a leucine-rich diet with or without physical aerobic exercise on muscle protein metabolism in Walker tumor-bearing rats. Young rats were divided into 4 groups that did or did not perform light aerobic exercise (swim training) and were on a leucine-rich diet or a control diet for 2 mo. After this time, these animals were implanted or not with tumors (subcutaneously) following groups for either control diet or leucine-rich diet fed rats: control, trained, tumor-bearing, and trained tumor-bearing. Twenty-one days after implantation, the tumor growth induced a decrease in the muscle protein synthesis and increased the catabolic process, which was associated with an increase in the expression of the ubiquitin-proteasome subunits (20S, 19S, and 11S). In contrast, the exercise program minimized the muscle degradation process and increased muscle myosin content. Additionally, leucine supplementation also modulated proteasome subunits, especially the 19S and 11S. In summary, the exercise has beneficial effects by reducing tumor growth, leading to an improvement in protein turnover especially when in conjunction with a leucine-rich diet. PMID:21058197

  9. Aerobic fitness does not modulate protein metabolism in response to increased exercise: a controlled trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Purpose: This study examined how a sudden increase in exercise energy expenditure affected whole body protein turnover and nitrogen balance in people of differing aerobic fitness. We hypothesized that whole-body protein turnover would be attenuated, and nitrogen balance would be preserved, in aerobi...

  10. Protein metabolism and requirements.

    PubMed

    Biolo, Gianni

    2013-01-01

    Skeletal muscle adaptation to critical illness includes insulin resistance, accelerated proteolysis, and increased release of glutamine and the other amino acids. Such amino acid efflux from skeletal muscle provides precursors for protein synthesis and energy fuel to the liver and to the rapidly dividing cells of the intestinal mucosa and the immune system. From these adaptation mechanisms, severe muscle wasting, glutamine depletion, and hyperglycemia, with increased patient morbidity and mortality, may ensue. Protein/amino acid nutrition, through either enteral or parenteral routes, plays a pivotal role in treatment of metabolic abnormalities in critical illness. In contrast to energy requirement, which can be accurately assessed by indirect calorimetry, methods to determine individual protein/amino acid needs are not currently available. In critical illness, a decreased ability of protein/amino acid intake to promote body protein synthesis is defined as anabolic resistance. This abnormality leads to increased protein/amino acid requirement and relative inefficiency of nutritional interventions. In addition to stress mediators, immobility and physical inactivity are key determinants of anabolic resistance. The development of mobility protocols in the intensive care unit should be encouraged to enhance the efficacy of nutrition. In critical illness, protein/amino acid requirement has been defined as the intake level associated with the lowest rate of catabolism. The optimal protein-sparing effects in patients receiving adequate energy are achieved when protein/amino acids are administered at rates between 1.3 and 1.5 g/kg/day. Extra glutamine supplementation is required in conditions of severe systemic inflammatory response. Protein requirement increases during hypocaloric feeding and in patients with acute renal failure on continuous renal replacement therapy. Evidence suggests that receiving adequate protein/amino acid intake may be more important than achieving

  11. Melatonin ameliorates metabolic risk factors, modulates apoptotic proteins, and protects the rat heart against diabetes-induced apoptosis.

    PubMed

    Amin, Ali H; El-Missiry, Mohamed A; Othman, Azza I

    2015-01-15

    The present study investigated the ability of melatonin in reducing metabolic risk factors and cardiac apoptosis induced by diabetes. Streptozotocin (60 mg/kg, i.p.) was injected into male rats, and after diabetic induction melatonin (10mg/kg i.g.) was administered orally for 21 days. Diabetic hearts showed increased number of apoptotic cells with downregulation of Bcl-2 and activation of p53 and CD95 as well as the caspases 9, 8 and 3. In addition, there was a significant decrease in insulin level, hyperglycemia, elevated HOMA-IR, glycosylated hemoglobin (HbA1c), total lipids, triglycerides, total cholesterol, low and very low-density lipoprotein and decreased high-density lipoprotein. These changes were coupled with a significant increase in the activities of creatin kinase-MB (CK-MB) and lactate dehydrogenase (LDH) in the serum of the diabetic rats indicating myocardium injury. Oral administration of melatonin for 3 weeks after diabetes induction ameliorated the levels of hyperglycemia, insulin, HbA1c, lipids profile and HOMA-IR. The oral melatonin treatment of diabetic rats significantly decreased the number of apoptotic cells in the heart compared to diabetic rats. It enhanced Bcl-2 expression and blocked the activation of CD95 as well as caspases 9, 8 and 3. These changes were accompanied with significant improvement of CK-MB and LDH in the serum indicating the ameliorative effect of melatonin on myocardium injury. Melatonin effectively ameliorated diabetic myocardium injury, apoptosis, reduced the metabolic risk factors and modulated important steps in both extrinsic and intrinsic pathways of apoptosis. Thus, melatonin may be a promising pharmacological agent for ameliorating potential cardiomyopathy associated with diabetes. PMID:25510232

  12. The Copper Metabolism MURR1 Domain Protein 1 (COMMD1) Modulates the Aggregation of Misfolded Protein Species in a Client-Specific Manner

    PubMed Central

    Vonk, Willianne I. M.; Kakkar, Vaishali; Bartuzi, Paulina; Jaarsma, Dick; Berger, Ruud; Hofker, Marten H.; Klomp, Leo W. J.; Wijmenga, Cisca; Kampinga, Harm H.; van de Sluis, Bart

    2014-01-01

    The Copper Metabolism MURR1 domain protein 1 (COMMD1) is a protein involved in multiple cellular pathways, including copper homeostasis, NF-κB and hypoxia signalling. Acting as a scaffold protein, COMMD1 mediates the levels, stability and proteolysis of its substrates (e.g. the copper-transporters ATP7B and ATP7A, RELA and HIF-1α). Recently, we established an interaction between the Cu/Zn superoxide dismutase 1 (SOD1) and COMMD1, resulting in a decreased maturation and activation of SOD1. Mutations in SOD1, associated with the progressive neurodegenerative disorder Amyotrophic Lateral Sclerosis (ALS), cause misfolding and aggregation of the mutant SOD1 (mSOD1) protein. Here, we identify COMMD1 as a novel regulator of misfolded protein aggregation as it enhances the formation of mSOD1 aggregates upon binding. Interestingly, COMMD1 co-localizes to the sites of mSOD1 inclusions and forms high molecular weight complexes in the presence of mSOD1. The effect of COMMD1 on protein aggregation is client-specific as, in contrast to mSOD1, COMMD1 decreases the abundance of mutant Parkin inclusions, associated with Parkinson’s disease. Aggregation of a polyglutamine-expanded Huntingtin, causative of Huntington’s disease, appears unaltered by COMMD1. Altogether, this study offers new research directions to expand our current knowledge on the mechanisms underlying aggregation disease pathologies. PMID:24691167

  13. On functional module detection in metabolic networks.

    PubMed

    Koch, Ina; Ackermann, Jörg

    2013-01-01

    Functional modules of metabolic networks are essential for understanding the metabolism of an organism as a whole. With the vast amount of experimental data and the construction of complex and large-scale, often genome-wide, models, the computer-aided identification of functional modules becomes more and more important. Since steady states play a key role in biology, many methods have been developed in that context, for example, elementary flux modes, extreme pathways, transition invariants and place invariants. Metabolic networks can be studied also from the point of view of graph theory, and algorithms for graph decomposition have been applied for the identification of functional modules. A prominent and currently intensively discussed field of methods in graph theory addresses the Q-modularity. In this paper, we recall known concepts of module detection based on the steady-state assumption, focusing on transition-invariants (elementary modes) and their computation as minimal solutions of systems of Diophantine equations. We present the Fourier-Motzkin algorithm in detail. Afterwards, we introduce the Q-modularity as an example for a useful non-steady-state method and its application to metabolic networks. To illustrate and discuss the concepts of invariants and Q-modularity, we apply a part of the central carbon metabolism in potato tubers (Solanum tuberosum) as running example. The intention of the paper is to give a compact presentation of known steady-state concepts from a graph-theoretical viewpoint in the context of network decomposition and reduction and to introduce the application of Q-modularity to metabolic Petri net models. PMID:24958145

  14. On Functional Module Detection in Metabolic Networks

    PubMed Central

    Koch, Ina; Ackermann, Jörg

    2013-01-01

    Functional modules of metabolic networks are essential for understanding the metabolism of an organism as a whole. With the vast amount of experimental data and the construction of complex and large-scale, often genome-wide, models, the computer-aided identification of functional modules becomes more and more important. Since steady states play a key role in biology, many methods have been developed in that context, for example, elementary flux modes, extreme pathways, transition invariants and place invariants. Metabolic networks can be studied also from the point of view of graph theory, and algorithms for graph decomposition have been applied for the identification of functional modules. A prominent and currently intensively discussed field of methods in graph theory addresses the Q-modularity. In this paper, we recall known concepts of module detection based on the steady-state assumption, focusing on transition-invariants (elementary modes) and their computation as minimal solutions of systems of Diophantine equations. We present the Fourier-Motzkin algorithm in detail. Afterwards, we introduce the Q-modularity as an example for a useful non-steady-state method and its application to metabolic networks. To illustrate and discuss the concepts of invariants and Q-modularity, we apply a part of the central carbon metabolism in potato tubers (Solanum tuberosum) as running example. The intention of the paper is to give a compact presentation of known steady-state concepts from a graph-theoretical viewpoint in the context of network decomposition and reduction and to introduce the application of Q-modularity to metabolic Petri net models. PMID:24958145

  15. SIRTUIN 1 AND SIRTUIN 3: PHYSIOLOGICAL MODULATORS OF METABOLISM

    PubMed Central

    Nogueiras, Ruben; Habegger, Kirk M.; Chaudhary, Nilika; Finan, Brian; Banks, Alexander S.; Dietrich, Marcelo O.; Horvath, Tamas L.; Sinclair, David A.; Pfluger, Paul T.; Tschöop, Matthias H.

    2013-01-01

    The sirtuins are a family of highly conserved NAD+-dependent deacetylases that act as cellular sensors to detect energy availability and modulate metabolic processes. Two sirtuins that are central to the control of metabolic processes are mammalian sirtuin 1 (SIRT1) and sirtuin 3 (SIRT3), which are localized to the nucleus and mitochondria, respectively. Both are activated by high NAD+ levels, a condition caused by low cellular energy status. By deacetylating a variety of proteins that induce catabolic processes while inhibiting anabolic processes, SIRT1 and SIRT3 coordinately increase cellular energy stores and ultimately maintain cellular energy homeostasis. Defects in the pathways controlled by SIRT1 and SIRT3 are known to result in various metabolic disorders. Consequently, activation of sirtuins by genetic or pharmacological means can elicit multiple metabolic benefits that protect mice from diet-induced obesity, type 2 diabetes, and nonalcoholic fatty liver disease. PMID:22811431

  16. Potassium Uptake Modulates Staphylococcus aureus Metabolism.

    PubMed

    Gries, Casey M; Sadykov, Marat R; Bulock, Logan L; Chaudhari, Sujata S; Thomas, Vinai C; Bose, Jeffrey L; Bayles, Kenneth W

    2016-01-01

    As a leading cause of community-associated and nosocomial infections, Staphylococcus aureus requires sophisticated mechanisms that function to maintain cellular homeostasis in response to its exposure to changing environmental conditions. The adaptation to stress and maintenance of homeostasis depend largely on membrane activity, including supporting electrochemical gradients and synthesis of ATP. This is largely achieved through potassium (K(+)) transport, which plays an essential role in maintaining chemiosmotic homeostasis, affects antimicrobial resistance, and contributes to fitness in vivo. Here, we report that S. aureus Ktr-mediated K(+) uptake is necessary for maintaining cytoplasmic pH and the establishment of a proton motive force. Metabolite analyses revealed that K(+) deficiency affects both metabolic and energy states of S. aureus by impairing oxidative phosphorylation and directing carbon flux toward substrate-level phosphorylation. Taken together, these results underline the importance of K(+) uptake in maintaining essential components of S. aureus metabolism. IMPORTANCE Previous studies describing mechanisms for K(+) uptake in S. aureus revealed that the Ktr-mediated K(+) transport system was required for normal growth under alkaline conditions but not under neutral or acidic conditions. This work focuses on the effect of K(+) uptake on S. aureus metabolism, including intracellular pH and carbon flux, and is the first to utilize a pH-dependent green fluorescent protein (GFP) to measure S. aureus cytoplasmic pH. These studies highlight the role of K(+) uptake in supporting proton efflux under alkaline conditions and uncover a critical role for K(+) uptake in establishing efficient carbon utilization. PMID:27340697

  17. Potassium Uptake Modulates Staphylococcus aureus Metabolism

    PubMed Central

    Gries, Casey M.; Sadykov, Marat R.; Bulock, Logan L.; Chaudhari, Sujata S.; Thomas, Vinai C.; Bose, Jeffrey L.

    2016-01-01

    ABSTRACT As a leading cause of community-associated and nosocomial infections, Staphylococcus aureus requires sophisticated mechanisms that function to maintain cellular homeostasis in response to its exposure to changing environmental conditions. The adaptation to stress and maintenance of homeostasis depend largely on membrane activity, including supporting electrochemical gradients and synthesis of ATP. This is largely achieved through potassium (K+) transport, which plays an essential role in maintaining chemiosmotic homeostasis, affects antimicrobial resistance, and contributes to fitness in vivo. Here, we report that S. aureus Ktr-mediated K+ uptake is necessary for maintaining cytoplasmic pH and the establishment of a proton motive force. Metabolite analyses revealed that K+ deficiency affects both metabolic and energy states of S. aureus by impairing oxidative phosphorylation and directing carbon flux toward substrate-level phosphorylation. Taken together, these results underline the importance of K+ uptake in maintaining essential components of S. aureus metabolism. IMPORTANCE Previous studies describing mechanisms for K+ uptake in S. aureus revealed that the Ktr-mediated K+ transport system was required for normal growth under alkaline conditions but not under neutral or acidic conditions. This work focuses on the effect of K+ uptake on S. aureus metabolism, including intracellular pH and carbon flux, and is the first to utilize a pH-dependent green fluorescent protein (GFP) to measure S. aureus cytoplasmic pH. These studies highlight the role of K+ uptake in supporting proton efflux under alkaline conditions and uncover a critical role for K+ uptake in establishing efficient carbon utilization. PMID:27340697

  18. Metabolic Adaptation and Protein Complexes in Prokaryotes

    PubMed Central

    Krüger, Beate; Liang, Chunguang; Prell, Florian; Fieselmann, Astrid; Moya, Andres; Schuster, Stefan; Völker, Uwe; Dandekar, Thomas

    2012-01-01

    Protein complexes are classified and have been charted in several large-scale screening studies in prokaryotes. These complexes are organized in a factory-like fashion to optimize protein production and metabolism. Central components are conserved between different prokaryotes; major complexes involve carbohydrate, amino acid, fatty acid and nucleotide metabolism. Metabolic adaptation changes protein complexes according to environmental conditions. Protein modification depends on specific modifying enzymes. Proteins such as trigger enzymes display condition-dependent adaptation to different functions by participating in several complexes. Several bacterial pathogens adapt rapidly to intracellular survival with concomitant changes in protein complexes in central metabolism and optimize utilization of their favorite available nutrient source. Regulation optimizes protein costs. Master regulators lead to up- and downregulation in specific subnetworks and all involved complexes. Long protein half-life and low level expression detaches protein levels from gene expression levels. However, under optimal growth conditions, metabolite fluxes through central carbohydrate pathways correlate well with gene expression. In a system-wide view, major metabolic changes lead to rapid adaptation of complexes and feedback or feedforward regulation. Finally, prokaryotic enzyme complexes are involved in crowding and substrate channeling. This depends on detailed structural interactions and is verified for specific effects by experiments and simulations. PMID:24957769

  19. Modulation of cardiac metabolism during myocardial ischemia.

    PubMed

    Chagas, Antonio C P; Dourado, Paulo M M; Galvão, Tatiana de Fátima Gonçalves

    2008-01-01

    Metabolic modulation during myocardial ischemia is possible by the use of specific drugs, which may induce a shift from free fatty acid towards predominantly glucose utilization by the myocardium to increase ATP generation per unit oxygen consumption. Three agents (trimetazidine, ranolazine, and perhexiline) have well-documented anti-ischaemic effects. However, perhexiline, the most potent agent currently available, requires plasma-level monitoring to avoid hepato-neuro-toxicity. Besides, the long-term safety of trimetazidine and ranolazine has yet to be established. In addition to their effect in ischemia, the potential use of these drugs in chronic heart failure is gaining recognition as clinical and experimental data are showing the improvement of myocardial function following treatment with several of them, even in the absence of ischemia. Future applications for this line of treatment is promising and deserves additional research. In particular, large, randomised, controlled trials investigating the effects of these agents on mortality and hospitalization rates due to coronary artery disease are needed. PMID:18991673

  20. Snail modulates cell metabolism in MDCK cells

    SciTech Connect

    Haraguchi, Misako; Indo, Hiroko P.; Iwasaki, Yasumasa; Iwashita, Yoichiro; Fukushige, Tomoko; Majima, Hideyuki J.; Izumo, Kimiko; Horiuchi, Masahisa; Kanekura, Takuro; Furukawa, Tatsuhiko; Ozawa, Masayuki

    2013-03-22

    Highlights: ► MDCK/snail cells were more sensitive to glucose deprivation than MDCK/neo cells. ► MDCK/snail cells had decreased oxidative phosphorylation, O{sub 2} consumption and ATP content. ► TCA cycle enzyme activity, but not expression, was lower in MDCK/snail cells. ► MDCK/snail cells showed reduced PDH activity and increased PDK1 expression. ► MDCK/snail cells showed reduced expression of GLS2 and ACLY. -- Abstract: Snail, a repressor of E-cadherin gene transcription, induces epithelial-to-mesenchymal transition and is involved in tumor progression. Snail also mediates resistance to cell death induced by serum depletion. By contrast, we observed that snail-expressing MDCK (MDCK/snail) cells undergo cell death at a higher rate than control (MDCK/neo) cells in low-glucose medium. Therefore, we investigated whether snail expression influences cell metabolism in MDCK cells. Although gylcolysis was not affected in MDCK/snail cells, they did exhibit reduced pyruvate dehydrogenase (PDH) activity, which controls pyruvate entry into the tricarboxylic acid (TCA) cycle. Indeed, the activity of multiple enzymes involved in the TCA cycle was decreased in MDCK/snail cells, including that of mitochondrial NADP{sup +}-dependent isocitrate dehydrogenase (IDH2), succinate dehydrogenase (SDH), and electron transport Complex II and Complex IV. Consequently, lower ATP content, lower oxygen consumption and increased survival under hypoxic conditions was also observed in MDCK/snail cells compared to MDCK/neo cells. In addition, the expression and promoter activity of pyruvate dehydrogenase kinase 1 (PDK1), which phosphorylates and inhibits the activity of PDH, was increased in MDCK/snail cells, while expression levels of glutaminase 2 (GLS2) and ATP-citrate lyase (ACLY), which are involved in glutaminolysis and fatty acid synthesis, were decreased in MDCK/snail cells. These results suggest that snail modulates cell metabolism by altering the expression and activity of

  1. Legionella pneumophila restrains autophagy by modulating the host's sphingolipid metabolism.

    PubMed

    Rolando, Monica; Escoll, Pedro; Buchrieser, Carmen

    2016-06-01

    Sphingolipids are bioactive molecules playing a key role as membrane components, but they are also central regulators of many intracellular processes including macroautophagy/autophagy. In particular, sphingosine-1-phosphate (S1P) is a critical mediator that controls the balance between sphingolipid-induced autophagy and cell death. S1P levels are adjusted via S1P synthesis, dephosphorylation or degradation, catalyzed by SGPL1 (sphingosine-1-phosphate lyase 1). Intracellular pathogens are able to modulate many different host cell pathways to allow their replication. We have found that infection of eukaryotic cells with the human pathogen Legionella pneumophila triggers a change in the host cell sphingolipid metabolism and specifically affects the levels of sphingosine. Indeed, L. pneumophila secretes a protein highly homologous to eukaryotic SGPL1 (named LpSPL). We solved the crystal structure of LpSPL and showed that it encodes lyase activity, targets the host's sphingolipid metabolism, and plays a role in starvation-induced autophagy during L. pneumophila infection to promote intracellular survival. PMID:27191778

  2. Bacterial microcompartments as metabolic modules for plant synthetic biology.

    PubMed

    Gonzalez-Esquer, C Raul; Newnham, Sarah E; Kerfeld, Cheryl A

    2016-07-01

    Bacterial microcompartments (BMCs) are megadalton-sized protein assemblies that enclose segments of metabolic pathways within cells. They increase the catalytic efficiency of the encapsulated enzymes while sequestering volatile or toxic intermediates from the bulk cytosol. The first BMCs discovered were the carboxysomes of cyanobacteria. Carboxysomes compartmentalize the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) with carbonic anhydrase. They enhance the carboxylase activity of RuBisCO by increasing the local concentration of CO2 in the vicinity of the enzyme's active site. As a metabolic module for carbon fixation, carboxysomes could be transferred to eukaryotic organisms (e.g. plants) to increase photosynthetic efficiency. Within the scope of synthetic biology, carboxysomes and other BMCs hold even greater potential when considered a source of building blocks for the development of nanoreactors or three-dimensional scaffolds to increase the efficiency of either native or heterologously expressed enzymes. The carboxysome serves as an ideal model system for testing approaches to engineering BMCs because their expression in cyanobacteria provides a sensitive screen for form (appearance of polyhedral bodies) and function (ability to grow on air). We recount recent progress in the re-engineering of the carboxysome shell and core to offer a conceptual framework for the development of BMC-based architectures for applications in plant synthetic biology. PMID:26991644

  3. Changes in metabolic modules under environmental variations

    NASA Astrophysics Data System (ADS)

    Almaas, Eivind

    2006-03-01

    During the last few years, network approaches have shown great promise as a tool to both analyze and provide understanding of complex systems as disparate as the world-wide web and cellular metabolism. Much effort has been focused on characterizing topological properties of such systems. However, in order to develop detailed descriptions of complex networks, we need to look beyond their topology and incorporate dynamical aspects. The cellular metabolism, where nodes correspond to metabolites and links indicate chemical reactions, is an excellent model system where theoretical predictions can be compared with experimental results. I will present recent insights into the principles governing the modular utilization of the cellular metabolism [1,2,3]. We find that, while most metabolic reactions have small fluxes, the metabolism's activity is dominated by an interconnected sub-network of reactions with very high fluxes [1]. For the bacteria H. pylori and E. coli and the yeast S. cerevisiae, the metabolism responds to changes in growth conditions by reorganizing the rates of select reactions predominantly within this high-flux backbone. Furthermore, these networks are organized around the metabolic core -- a set of reactions that are always in use [2]. Strikingly, the activity of the metabolic core reactions is highly synchronized, and the core reactions are significantly more essential and evolutionary conserved than the non-core ones. [1] E. Almaas, B. Kovacs, T. Vicsek, Z.N. Oltvai and A.-L. Barabasi. Nature 427, 839 (2004). [2] E. Almaas, Z.N. Oltvai and A.-L. Barabasi. PLoS Comput. Biol. In press (2005). 10.1371/journal.pcbi.0010068.eor [3] P.J. Macdonald, E. Almaas and A.-L. Barabasi. Europhys. Lett. 72, 308 (2005).

  4. Module organization and variance in protein-protein interaction networks

    PubMed Central

    Lin, Chun-Yu; Lee, Tsai-Ling; Chiu, Yi-Yuan; Lin, Yi-Wei; Lo, Yu-Shu; Lin, Chih-Ta; Yang, Jinn-Moon

    2015-01-01

    A module is a group of closely related proteins that act in concert to perform specific biological functions through protein–protein interactions (PPIs) that occur in time and space. However, the underlying module organization and variance remain unclear. In this study, we collected module templates to infer respective module families, including 58,041 homologous modules in 1,678 species, and PPI families using searches of complete genomic database. We then derived PPI evolution scores and interface evolution scores to describe the module elements, including core and ring components. Functions of core components were highly correlated with those of essential genes. In comparison with ring components, core proteins/PPIs were conserved across multiple species. Subsequently, protein/module variance of PPI networks confirmed that core components form dynamic network hubs and play key roles in various biological functions. Based on the analyses of gene essentiality, module variance, and gene co-expression, we summarize the observations of module organization and variance as follows: 1) a module consists of core and ring components; 2) core components perform major biological functions and collaborate with ring components to execute certain functions in some cases; 3) core components are more conserved and essential during organizational changes in different biological states or conditions. PMID:25797237

  5. Leishmania infantum modulates host macrophage mitochondrial metabolism by hijacking the SIRT1-AMPK axis.

    PubMed

    Moreira, Diana; Rodrigues, Vasco; Abengozar, Maria; Rivas, Luis; Rial, Eduardo; Laforge, Mireille; Li, Xiaoling; Foretz, Marc; Viollet, Benoit; Estaquier, Jérôme; Cordeiro da Silva, Anabela; Silvestre, Ricardo

    2015-03-01

    Metabolic manipulation of host cells by intracellular pathogens is currently recognized to play an important role in the pathology of infection. Nevertheless, little information is available regarding mitochondrial energy metabolism in Leishmania infected macrophages. Here, we demonstrate that during L. infantum infection, macrophages switch from an early glycolytic metabolism to an oxidative phosphorylation, and this metabolic deviation requires SIRT1 and LKB1/AMPK. SIRT1 or LBK1 deficient macrophages infected with L. infantum failed to activate AMPK and up-regulate its targets such as Slc2a4 and Ppargc1a, which are essential for parasite growth. As a result, impairment of metabolic switch caused by SIRT1 or AMPK deficiency reduces parasite load in vitro and in vivo. Overall, our work demonstrates the importance of SIRT1 and AMPK energetic sensors for parasite intracellular survival and proliferation, highlighting the modulation of these proteins as potential therapeutic targets for the treatment of leishmaniasis. PMID:25738568

  6. Leishmania infantum Modulates Host Macrophage Mitochondrial Metabolism by Hijacking the SIRT1-AMPK Axis

    PubMed Central

    Moreira, Diana; Rodrigues, Vasco; Abengozar, Maria; Rivas, Luis; Rial, Eduardo; Laforge, Mireille; Li, Xiaoling; Foretz, Marc; Viollet, Benoit; Estaquier, Jérôme; Cordeiro da Silva, Anabela; Silvestre, Ricardo

    2015-01-01

    Metabolic manipulation of host cells by intracellular pathogens is currently recognized to play an important role in the pathology of infection. Nevertheless, little information is available regarding mitochondrial energy metabolism in Leishmania infected macrophages. Here, we demonstrate that during L. infantum infection, macrophages switch from an early glycolytic metabolism to an oxidative phosphorylation, and this metabolic deviation requires SIRT1 and LKB1/AMPK. SIRT1 or LBK1 deficient macrophages infected with L. infantum failed to activate AMPK and up-regulate its targets such as Slc2a4 and Ppargc1a, which are essential for parasite growth. As a result, impairment of metabolic switch caused by SIRT1 or AMPK deficiency reduces parasite load in vitro and in vivo. Overall, our work demonstrates the importance of SIRT1 and AMPK energetic sensors for parasite intracellular survival and proliferation, highlighting the modulation of these proteins as potential therapeutic targets for the treatment of leishmaniasis. PMID:25738568

  7. Stress-responsive hydroxycinnamate glycosyltransferase modulates phenylpropanoid metabolism in Populus

    PubMed Central

    Babst, Benjamin A.; Chen, Han-Yi; Wang, Hong-Qiang; Payyavula, Raja S.; Thomas, Tina P.; Harding, Scott A.; Tsai, Chung-Jui

    2014-01-01

    The diversity of phenylpropanoids offers a rich inventory of bioactive chemicals that can be exploited for plant improvement and human health. Recent evidence suggests that glycosylation may play a role in the partitioning of phenylpropanoid precursors for a variety of downstream uses. This work reports the functional characterization of a stress-responsive glycosyltransferase, GT1-316 in Populus. GT1-316 belongs to the UGT84A subfamily of plant glycosyltransferase family 1 and is designated UGT84A17. Recombinant protein analysis showed that UGT84A17 is a hydroxycinnamate glycosyltransferase and able to accept a range of unsubstituted and substituted cinnamic and benzoic acids as substrates in vitro. Overexpression of GT1-316 in transgenic Populus led to plant-wide increases of hydroxycinnamoyl-glucose esters, which were further elevated under N-limiting conditions. Levels of the two most abundant flavonoid glycosides, rutin and kaempferol-3-O-rutinoside, decreased, while levels of other less abundant flavonoid and phenylpropanoid conjugates increased in leaves of the GT1-316-overexpressing plants. Transcript levels of representative phenylpropanoid pathway genes were unchanged in transgenic plants, supporting a glycosylation-mediated redirection of phenylpropanoid carbon flow as opposed to enhanced phenylpropanoid pathway flux. The metabolic response of N-replete transgenic plants overlapped with that of N-stressed wild types, as the majority of phenylpropanoid derivatives significantly affected by GT1-316 overexpression were also significantly changed by N stress in the wild types. These results suggest that UGT84A17 plays an important role in phenylpropanoid metabolism by modulating biosynthesis of hydroxycinnamoyl-glucose esters and their derivatives in response to developmental and environmental cues. PMID:24803501

  8. HDAC Inhibition Modulates Cardiac PPARs and Fatty Acid Metabolism in Diabetic Cardiomyopathy.

    PubMed

    Lee, Ting-I; Kao, Yu-Hsun; Tsai, Wen-Chin; Chung, Cheng-Chih; Chen, Yao-Chang; Chen, Yi-Jen

    2016-01-01

    Peroxisome proliferator-activated receptors (PPARs) regulate cardiac glucose and lipid homeostasis. Histone deacetylase (HDAC) inhibitor has anti-inflammatory effects which may play a key role in modulating PPARs and fatty acid metabolism. The aim of this study was to investigate whether HDAC inhibitor, MPT0E014, can modulate myocardial PPARs, inflammation, and fatty acid metabolism in diabetes mellitus (DM) cardiomyopathy. Electrocardiography, echocardiography, and western blotting were used to evaluate the electrophysiological activity, cardiac structure, fatty acid metabolism, inflammation, and PPAR isoform expressions in the control and streptozotocin-nicotinamide-induced DM rats with or without MPT0E014. Compared to control, DM and MPT0E014-treated DM rats had elevated blood glucose levels and lower body weights. However, MPT0E014-treated DM and control rats had smaller left ventricular end-diastolic diameter and shorter QT interval than DM rats. The control and MPT0E014-treated DM rats had greater cardiac PPAR-α and PPAR-δ protein expressions, but less cardiac PPAR-γ than DM rats. Moreover, control and MPT0E014-treated DM rats had lower concentrations of 5' adenosine monophosphate-activated protein kinase 2α, PPAR-γ coactivator 1α, phosphorylated acetyl CoA carboxylase, cluster of differentiation 36, diacylglycerol acyltransferase 1 (DGAT1), DGAT2, tumor necrosis factor-α, and interleukin-6 protein than DM rats. HDAC inhibition significantly attenuated DM cardiomyopathy through modulation of cardiac PPARS, fatty acid metabolism, and proinflammatory cytokines. PMID:27446205

  9. Effect of acute heat stress on plant nutrient metabolism proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abrupt heating decreased the levels (per unit total root protein) of all but one of the nutrient metabolism proteins examined, and for most of the proteins, effects were greater for severe vs. moderate heat stress. For many of the nutrient metabolism proteins, initial effects of heat (1 d) were r...

  10. Play down protein to play up metabolism?

    PubMed Central

    Müller, Timo D.; Tschöp, Matthias H.

    2014-01-01

    Who among us hasn’t fantasized about a diet that allows ingestion of a surfeit of calories that are burned off effortlessly by ramping up energy expenditure? In this issue of the JCI, research led by Christopher Morrison suggests that this dream may become a reality; however, a complete understanding of the molecular interface that connects nutrient choices with our cellular metabolism will be required. Laeger et al. show that the expression and secretion of the weight-reducing hormone fibroblast growth factor 21 (FGF21) is regulated by dietary proteins and not, as has been heretofore assumed, simply triggered by reduced caloric intake. This study not only sheds new light on the role of FGF21 in systems metabolism, but also on the ways our bodies cope with the ever-changing availability of different dietary macronutrients. PMID:25133420

  11. Protein modules and signalling networks

    NASA Astrophysics Data System (ADS)

    Pawson, Tony

    1995-02-01

    Communication between cells assumes particular importance in multicellular organisms. The growth, migration and differentiation of cells in the embryo, and their organization into specific tissues, depend on signals transmitted from one cell to another. In the adult, cell signalling orchestrates normal cellular behaviour and responses to wounding and infection. The consequences of breakdowns in this signalling underlie cancer, diabetes and disorders of the immune and cardiovascular systems. Conserved protein domains that act as key regulatory participants in many of these different signalling pathways are highlighted.

  12. Positive modulator of bone morphogenic protein-2

    DOEpatents

    Zamora, Paul O.; Pena, Louis A.; Lin, Xinhua; Takahashi, Kazuyuki

    2009-01-27

    Compounds of the present invention of formula I and formula II are disclosed in the specification and wherein the compounds are modulators of Bone Morphogenic Protein activity. Compounds are synthetic peptides having a non-growth factor heparin binding region, a linker, and sequences that bind specifically to a receptor for Bone Morphogenic Protein. Uses of compounds of the present invention in the treatment of bone lesions, degenerative joint disease and to enhance bone formation are disclosed.

  13. Chemoprotective activity of boldine: modulation of drug-metabolizing enzymes.

    PubMed

    Kubínová, R; Machala, M; Minksová, K; Neca, J; Suchý, V

    2001-03-01

    Possible chemoprotective effects of the naturally occurring alkaloid boldine, a major alkaloid of boldo (Peumus boldus Mol.) leaves and bark, including in vitro modulations of drug-metabolizing enzymes in mouse hepatoma Hepa-1 cell line and mouse hepatic microsomes, were investigated. Boldine manifested inhibition activity on hepatic microsomal CYP1A-dependent 7-ethoxyresorufin O-deethylase and CYP3A-dependent testosterone 6 beta-hydroxylase activities and stimulated glutathione S-transferase activity in Hepa-1 cells. In addition to the known antioxidant activity, boldine could decrease the metabolic activation of other xenobiotics including chemical mutagens. PMID:11265593

  14. Dysregulation of skeletal muscle protein metabolism by alcohol.

    PubMed

    Steiner, Jennifer L; Lang, Charles H

    2015-05-01

    Alcohol abuse, either by acute intoxication or prolonged excessive consumption, leads to pathological changes in many organs and tissues including skeletal muscle. As muscle protein serves not only a contractile function but also as a metabolic reserve for amino acids, which are used to support the energy needs of other tissues, its content is tightly regulated and dynamic. This review focuses on the etiology by which alcohol perturbs skeletal muscle protein balance and thereby over time produces muscle wasting and weakness. The preponderance of data suggest that alcohol primarily impairs global protein synthesis, under basal conditions as well as in response to several anabolic stimuli including growth factors, nutrients, and muscle contraction. This inhibitory effect of alcohol is mediated, at least in part, by a reduction in mTOR kinase activity via a mechanism that remains poorly defined but likely involves altered protein-protein interactions within mTOR complex 1. Furthermore, alcohol can exacerbate the decrement in mTOR and/or muscle protein synthesis present in other catabolic states. In contrast, alcohol-induced changes in muscle protein degradation, either global or via specific modulation of the ubiquitin-proteasome or autophagy pathways, are relatively inconsistent and may be model dependent. Herein, changes produced by acute intoxication versus chronic ingestion are contrasted in relation to skeletal muscle metabolism, and limitations as well as opportunities for future research are discussed. As the proportion of more economically developed countries ages and chronic illness becomes more prevalent, a better understanding of the etiology of biomedical consequences of alcohol use disorders is warranted. PMID:25759394

  15. Dysregulation of skeletal muscle protein metabolism by alcohol

    PubMed Central

    Steiner, Jennifer L.

    2015-01-01

    Alcohol abuse, either by acute intoxication or prolonged excessive consumption, leads to pathological changes in many organs and tissues including skeletal muscle. As muscle protein serves not only a contractile function but also as a metabolic reserve for amino acids, which are used to support the energy needs of other tissues, its content is tightly regulated and dynamic. This review focuses on the etiology by which alcohol perturbs skeletal muscle protein balance and thereby over time produces muscle wasting and weakness. The preponderance of data suggest that alcohol primarily impairs global protein synthesis, under basal conditions as well as in response to several anabolic stimuli including growth factors, nutrients, and muscle contraction. This inhibitory effect of alcohol is mediated, at least in part, by a reduction in mTOR kinase activity via a mechanism that remains poorly defined but likely involves altered protein-protein interactions within mTOR complex 1. Furthermore, alcohol can exacerbate the decrement in mTOR and/or muscle protein synthesis present in other catabolic states. In contrast, alcohol-induced changes in muscle protein degradation, either global or via specific modulation of the ubiquitin-proteasome or autophagy pathways, are relatively inconsistent and may be model dependent. Herein, changes produced by acute intoxication versus chronic ingestion are contrasted in relation to skeletal muscle metabolism, and limitations as well as opportunities for future research are discussed. As the proportion of more economically developed countries ages and chronic illness becomes more prevalent, a better understanding of the etiology of biomedical consequences of alcohol use disorders is warranted. PMID:25759394

  16. Aging, exercise, and muscle protein metabolism.

    PubMed

    Koopman, René; van Loon, Luc J C

    2009-06-01

    Aging is accompanied by a progressive loss of skeletal muscle mass and strength, leading to the loss of functional capacity and an increased risk of developing chronic metabolic disease. The age-related loss of skeletal muscle mass is attributed to a disruption in the regulation of skeletal muscle protein turnover, resulting in an imbalance between muscle protein synthesis and degradation. As basal (fasting) muscle protein synthesis rates do not seem to differ substantially between the young and elderly, many research groups have started to focus on the muscle protein synthetic response to the main anabolic stimuli, i.e., food intake and physical activity. Recent studies suggest that the muscle protein synthetic response to food intake is blunted in the elderly. The latter is now believed to represent a key factor responsible for the age-related decline in skeletal muscle mass. Physical activity and/or exercise stimulate postexercise muscle protein accretion in both the young and elderly. However, the latter largely depends on the timed administration of amino acids and/or protein before, during, and/or after exercise. Prolonged resistance type exercise training represents an effective therapeutic strategy to augment skeletal muscle mass and improve functional performance in the elderly. The latter shows that the ability of the muscle protein synthetic machinery to respond to anabolic stimuli is preserved up to very old age. Research is warranted to elucidate the interaction between nutrition, exercise, and the skeletal muscle adaptive response. The latter is needed to define more effective strategies that will maximize the therapeutic benefits of lifestyle intervention in the elderly. PMID:19131471

  17. Metabolic Inflammation-Differential Modulation by Dietary Constituents.

    PubMed

    Lyons, Claire L; Kennedy, Elaine B; Roche, Helen M

    2016-01-01

    Obesity arises from a sustained positive energy balance which triggers a pro-inflammatory response, a key contributor to metabolic diseases such as T2D. Recent studies, focused on the emerging area of metabolic-inflammation, highlight that specific metabolites can modulate the functional nature and inflammatory phenotype of immune cells. In obesity, expanding adipose tissue attracts immune cells, creating an inflammatory environment within this fatty acid storage organ. Resident immune cells undergo both a pro-inflammatory and metabolic switch in their function. Inflammatory mediators, such as TNF-α and IL-1β, are induced by saturated fatty acids and disrupt insulin signaling. Conversely, monounsaturated and polyunsaturated fatty acids do not interrupt metabolism and inflammation to the same extent. AMPK links inflammation, metabolism and T2D, with roles to play in all and is influenced negatively by obesity. Lipid spillover results in hepatic lipotoxicity and steatosis. Also in skeletal muscle, excessive FFA can impede insulin's action and promote inflammation. Ectopic fat can also affect pancreatic β-cell function, thereby contributing to insulin resistance. Therapeutics, lifestyle changes, supplements and dietary manipulation are all possible avenues to combat metabolic inflammation and the subsequent insulin resistant state which will be explored in the current review. PMID:27128935

  18. Metabolic Inflammation-Differential Modulation by Dietary Constituents

    PubMed Central

    Lyons, Claire L.; Kennedy, Elaine B.; Roche, Helen M.

    2016-01-01

    Obesity arises from a sustained positive energy balance which triggers a pro-inflammatory response, a key contributor to metabolic diseases such as T2D. Recent studies, focused on the emerging area of metabolic-inflammation, highlight that specific metabolites can modulate the functional nature and inflammatory phenotype of immune cells. In obesity, expanding adipose tissue attracts immune cells, creating an inflammatory environment within this fatty acid storage organ. Resident immune cells undergo both a pro-inflammatory and metabolic switch in their function. Inflammatory mediators, such as TNF-α and IL-1β, are induced by saturated fatty acids and disrupt insulin signaling. Conversely, monounsaturated and polyunsaturated fatty acids do not interrupt metabolism and inflammation to the same extent. AMPK links inflammation, metabolism and T2D, with roles to play in all and is influenced negatively by obesity. Lipid spillover results in hepatic lipotoxicity and steatosis. Also in skeletal muscle, excessive FFA can impede insulin’s action and promote inflammation. Ectopic fat can also affect pancreatic β-cell function, thereby contributing to insulin resistance. Therapeutics, lifestyle changes, supplements and dietary manipulation are all possible avenues to combat metabolic inflammation and the subsequent insulin resistant state which will be explored in the current review. PMID:27128935

  19. Complex Reconstitution from Individual Protein Modules.

    PubMed

    Basquin, Jérôme; Taschner, Michael; Lorentzen, Esben

    2016-01-01

    Cellular function relies on protein complexes that work as nano-machines. The structure and function of protein complexes is an outcome of the specific combination of protein subunits, or modules, within the complex. A major focus of molecular biology is thus to understand how protein subunits assemble to form complexes with distinct biological function. To this end, in vitro reconstitution of complexes from individual subunits to study their assembly, structure and activity is of central importance. With purified individual subunits and sub-modules at hand one can systematically dissect the hierarchical assembly of larger complexes using direct protein-protein interaction assays. Furthermore, activity assays can be carried out with individual subunits or smaller sub-complexes and compared to those of the fully assembled complex to precisely map functional sites and provide a molecular basis for in vivo observations. In this chapter we review methods for protein complex assembly from individual subunits and provide examples of advantages and potential pitfalls to this approach. PMID:27165333

  20. Chemical modulation of glycerolipid signaling and metabolic pathways

    PubMed Central

    Scott, Sarah A.; Mathews, Thomas P.; Ivanova, Pavlina T.; Lindsley, Craig W.; Brown, H. Alex

    2014-01-01

    Thirty years ago, glycerolipids captured the attention of biochemical researchers as novel cellular signaling entities. We now recognize that these biomolecules occupy signaling nodes critical to a number of physiological and pathological processes. Thus, glycerolipid-metabolizing enzymes present attractive targets for new therapies. A number of fields—ranging from neuroscience and cancer to diabetes and obesity—have elucidated the signaling properties of glycerolipids. The biochemical literature teems with newly emerging small molecule inhibitors capable of manipulating glycerolipid metabolism and signaling. This ever-expanding pool of chemical modulators appears daunting to those interested in exploiting glycerolipid-signaling pathways in their model system of choice. This review distills the current body of literature surrounding glycerolipid metabolism into a more approachable format, facilitating the application of small molecule inhibitors to novel systems. PMID:24440821

  1. Metabolic modulation and cellular therapy of cardiac dysfunction and failure

    PubMed Central

    Revenco, Diana; Morgan, James P

    2009-01-01

    Abstract At present the prevalence of heart failure rises along with aging of the population. Current heart failure therapeutic options are directed towards disease prevention via neurohormonal antagonism (β-blockers, angiotensin converting enzyme inhibitors and/or angiotensin receptor blockers and aldosterone antagonists), symptomatic treatment with diuretics and digitalis and use of biventricular pacing and defibrillators in a special subset of patients. Despite these therapies and device interventions heart failure remains a progressive disease with high mortality and morbidity rates. The number of patients who survive to develop advanced heart failure is increasing. These patients require new therapeutic strategies. In this review two of emerging therapies in the treatment of heart failure are discussed: metabolic modulation and cellular therapy. Metabolic modulation aims to optimize the myocardial energy utilization via shifting the substrate utilization from free fatty acids to glucose. Cellular therapy on the other hand has the goal to achieve true cardiac regeneration. We review the experimental data that support these strategies as well as the available pharmacological agents for metabolic modulation and clinical application of cellular therapy. PMID:19382894

  2. Foldons, Protein Structural Modules, and Exons

    NASA Astrophysics Data System (ADS)

    Panchenko, Anna R.; Luthey-Schulten, Zaida; Wolynes, Peter G.

    1996-03-01

    Foldons, which are kinetically competent, quasi-independently folding units of a protein, may be defined using energy landscape analysis. Foldons can be identified by maxima in a scan of the ratio of a contiguous segment's energetic stability gap to the energy variance of that segment's molten globule states, reflecting the requirement of minimal frustration. The predicted foldons are compared with the exons and structural modules for 16 of the 30 proteins studied. Statistical analysis indicates a strong correlation between the energetically determined foldons and Go's geometrically defined structural modules, but there are marked sequence-dependent effects. There is only a weak correlation of foldons to exons. For γ II-crystallin, myoglobin, barnase, α -lactalbumin, and cytochrome c the foldons and some noncontiguous clusters of foldons compare well with intermediates observed in experiment.

  3. Protein acetylation in metabolism - metabolites and cofactors.

    PubMed

    Menzies, Keir J; Zhang, Hongbo; Katsyuba, Elena; Auwerx, Johan

    2016-01-01

    Reversible acetylation was initially described as an epigenetic mechanism regulating DNA accessibility. Since then, this process has emerged as a controller of histone and nonhistone acetylation that integrates key physiological processes such as metabolism, circadian rhythm and cell cycle, along with gene regulation in various organisms. The widespread and reversible nature of acetylation also revitalized interest in the mechanisms that regulate lysine acetyltransferases (KATs) and deacetylases (KDACs) in health and disease. Changes in protein or histone acetylation are especially relevant for many common diseases including obesity, diabetes mellitus, neurodegenerative diseases and cancer, as well as for some rare diseases such as mitochondrial diseases and lipodystrophies. In this Review, we examine the role of reversible acetylation in metabolic control and how changes in levels of metabolites or cofactors, including nicotinamide adenine dinucleotide, nicotinamide, coenzyme A, acetyl coenzyme A, zinc and butyrate and/or β-hydroxybutyrate, directly alter KAT or KDAC activity to link energy status to adaptive cellular and organismal homeostasis. PMID:26503676

  4. Regulation of glutamate metabolism by protein kinases in mycobacteria.

    PubMed

    O'Hare, Helen M; Durán, Rosario; Cerveñansky, Carlos; Bellinzoni, Marco; Wehenkel, Anne Marie; Pritsch, Otto; Obal, Gonzalo; Baumgartner, Jens; Vialaret, Jérome; Johnsson, Kai; Alzari, Pedro M

    2008-12-01

    Protein kinase G of Mycobacterium tuberculosis has been implicated in virulence and in regulation of glutamate metabolism. Here we show that this kinase undergoes a pattern of autophosphorylation that is distinct from that of other M. tuberculosis protein kinases characterized to date and we identify GarA as a substrate for phosphorylation by PknG. Autophosphorylation of PknG has little effect on kinase activity but promotes binding to GarA, an interaction that is also detected in living mycobacteria. PknG phosphorylates GarA at threonine 21, adjacent to the residue phosphorylated by PknB (T22), and these two phosphorylation events are mutually exclusive. Like the homologue OdhI from Corynebacterium glutamicum, the unphosphorylated form of GarA is shown to inhibit alpha-ketoglutarate decarboxylase in the TCA cycle. Additionally GarA is found to bind and modulate the activity of a large NAD(+)-specific glutamate dehydrogenase with an unusually low affinity for glutamate. Previous reports of a defect in glutamate metabolism caused by pknG deletion may thus be explained by the effect of unphosphorylated GarA on these two enzyme activities, which may also contribute to the attenuation of virulence. PMID:19019160

  5. Metabolic effects of milk protein intake strongly depend on pre-existing metabolic and exercise status.

    PubMed

    Melnik, Bodo C; Schmitz, Gerd; John, Swen; Carrera-Bastos, Pedro; Lindeberg, Staffan; Cordain, Loren

    2013-01-01

    Milk protein intake has recently been suggested to improve metabolic health. This Perspective provides evidence that metabolic effects of milk protein intake have to be regarded in the context of the individual's pre-existing metabolic and exercise status. Milk proteins provide abundant branched-chain amino acids (BCAAs) and glutamine. Plasma BCAAs and glutamine are increased in obesity and insulin resistance, but decrease after gastric bypass surgery resulting in weight loss and improved insulin sensitivity. Milk protein consumption results in postprandial hyperinsulinemia in obese subjects, increases body weight of overweight adolescents and may thus deteriorate pre-existing metabolic disturbances of obese, insulin resistant individuals. PMID:24225036

  6. Metabolic effects of milk protein intake strongly depend on pre-existing metabolic and exercise status

    PubMed Central

    2013-01-01

    Milk protein intake has recently been suggested to improve metabolic health. This Perspective provides evidence that metabolic effects of milk protein intake have to be regarded in the context of the individual’s pre-existing metabolic and exercise status. Milk proteins provide abundant branched-chain amino acids (BCAAs) and glutamine. Plasma BCAAs and glutamine are increased in obesity and insulin resistance, but decrease after gastric bypass surgery resulting in weight loss and improved insulin sensitivity. Milk protein consumption results in postprandial hyperinsulinemia in obese subjects, increases body weight of overweight adolescents and may thus deteriorate pre-existing metabolic disturbances of obese, insulin resistant individuals. PMID:24225036

  7. Streptomyces rhizobacteria modulate the secondary metabolism of Eucalyptus plants.

    PubMed

    Salla, Tamiris Daros; da Silva, Ramos; Astarita, Leandro Vieira; Santarém, Eliane Romanato

    2014-12-01

    The genus Eucalyptus comprises economically important species, such as Eucalyptus grandis and Eucalyptus globulus, used especially as a raw material in many industrial sectors. Species of Eucalyptus are very susceptible to pathogens, mainly fungi, which leads to mortality of plant cuttings in rooting phase. One alternative to promote plant health and development is the potential use of microorganisms that act as agents for biological control, such as plant growth-promoting rhizobacteria (PGPR). Rhizobacteria Streptomyces spp have been considered as PGPR. This study aimed at selecting strains of Streptomyces with ability to promote plant growth and modulate secondary metabolism of E. grandis and E. globulus in vitro plants. The experiments assessed the development of plants (root number and length), changes in key enzymes in plant defense (polyphenol oxidase and peroxidase) and induction of secondary compounds(total phenolic and quercetinic flavonoid fraction). The isolate Streptomyces PM9 showed highest production of indol-3-acetic acid and the best potential for root induction. Treatment of Eucalyptus roots with Streptomyces PM9 caused alterations in enzymes activities during the period of co-cultivation (1-15 days), as well as in the levels of phenolic compounds and flavonoids. Shoots also showed alteration in the secondary metabolism, suggesting induced systemic response. The ability of Streptomyces sp. PM9 on promoting root growth, through production of IAA, and possible role on modulation of secondary metabolism of Eucalyptus plants characterizes this isolate as PGPR and indicates its potential use as a biological control in forestry. PMID:25394796

  8. HDAC Inhibition Modulates Cardiac PPARs and Fatty Acid Metabolism in Diabetic Cardiomyopathy

    PubMed Central

    Lee, Ting-I; Tsai, Wen-Chin; Chung, Cheng-Chih; Chen, Yao-Chang; Chen, Yi-Jen

    2016-01-01

    Peroxisome proliferator-activated receptors (PPARs) regulate cardiac glucose and lipid homeostasis. Histone deacetylase (HDAC) inhibitor has anti-inflammatory effects which may play a key role in modulating PPARs and fatty acid metabolism. The aim of this study was to investigate whether HDAC inhibitor, MPT0E014, can modulate myocardial PPARs, inflammation, and fatty acid metabolism in diabetes mellitus (DM) cardiomyopathy. Electrocardiography, echocardiography, and western blotting were used to evaluate the electrophysiological activity, cardiac structure, fatty acid metabolism, inflammation, and PPAR isoform expressions in the control and streptozotocin-nicotinamide-induced DM rats with or without MPT0E014. Compared to control, DM and MPT0E014-treated DM rats had elevated blood glucose levels and lower body weights. However, MPT0E014-treated DM and control rats had smaller left ventricular end-diastolic diameter and shorter QT interval than DM rats. The control and MPT0E014-treated DM rats had greater cardiac PPAR-α and PPAR-δ protein expressions, but less cardiac PPAR-γ than DM rats. Moreover, control and MPT0E014-treated DM rats had lower concentrations of 5′ adenosine monophosphate-activated protein kinase 2α, PPAR-γ coactivator 1α, phosphorylated acetyl CoA carboxylase, cluster of differentiation 36, diacylglycerol acyltransferase 1 (DGAT1), DGAT2, tumor necrosis factor-α, and interleukin-6 protein than DM rats. HDAC inhibition significantly attenuated DM cardiomyopathy through modulation of cardiac PPARS, fatty acid metabolism, and proinflammatory cytokines. PMID:27446205

  9. Relationship between asparagine metabolism and protein concentration in soybean seed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The relationship between asparagine metabolism and protein concentration was investigated in soybean seed. Phenotyping of a population of recombinant inbred lines adapted to Illinois confirmed a positive correlation between free asparagine levels in developing seeds and protein concentration at matu...

  10. Human Skeletal Muscle Protein Metabolism Responses to Amino Acid Nutrition.

    PubMed

    Mitchell, W Kyle; Wilkinson, Daniel J; Phillips, Bethan E; Lund, Jonathan N; Smith, Kenneth; Atherton, Philip J

    2016-07-01

    Healthy individuals maintain remarkably constant skeletal muscle mass across much of adult life, suggesting the existence of robust homeostatic mechanisms. Muscle exists in dynamic equilibrium whereby the influx of amino acids (AAs) and the resulting increases in muscle protein synthesis (MPS) associated with the intake of dietary proteins cancel out the efflux of AAs from muscle protein breakdown that occurs between meals. Dysregulated proteostasis is evident with aging, especially beyond the sixth decade of life. Women and men aged 75 y lose muscle mass at a rate of ∼0.7% and 1%/y, respectively (sarcopenia), and lose strength 2- to 5-fold faster (dynapenia) as muscle "quality" decreases. Factors contributing to the disruption of an otherwise robust proteostatic system represent targets for potential therapies that promote healthy aging. Understanding age-related impairments in anabolic responses to AAs and identifying strategies to mitigate these factors constitute major areas of interest. Numerous studies have aimed to identify 1) the influence of distinct protein sources on absorption kinetics and muscle anabolism, 2) the latency and time course of MPS responses to protein/AAs, 3) the impacts of protein/AA intake on muscle microvascular recruitment, and 4) the role of certain AAs (e.g., leucine) as signaling molecules, which are able to trigger anabolic pathways in tissues. This review aims to discuss these 4 issues listed, to provide historical and modern perspectives of AAs as modulators of human skeletal muscle protein metabolism, to describe how advances in stable isotope/mass spectrometric approaches and instrumentation have underpinned these advances, and to highlight relevant differences between young adults and older individuals. Whenever possible, observations are based on human studies, with additional consideration of relevant nonhuman studies. PMID:27422520

  11. Modulation of lipid metabolic defects rescues cleft palate in Tgfbr2 mutant mice.

    PubMed

    Iwata, Junichi; Suzuki, Akiko; Pelikan, Richard C; Ho, Thach-Vu; Sanchez-Lara, Pedro A; Chai, Yang

    2014-01-01

    Mutations in transforming growth factor beta (TGFβ) receptor type II (TGFBR2) cause Loeys-Dietz syndrome, characterized by craniofacial and cardiovascular abnormalities. Mice with a deletion of Tgfbr2 in cranial neural crest cells (Tgfbr2(fl/fl);Wnt1-Cre mice) develop cleft palate as the result of abnormal TGFβ signaling activation. However, little is known about metabolic processes downstream of TGFβ signaling during palatogenesis. Here, we show that Tgfbr2 mutant palatal mesenchymal cells spontaneously accumulate lipid droplets, resulting from reduced lipolysis activity. Tgfbr2 mutant palatal mesenchymal cells failed to respond to the cell proliferation stimulator sonic hedgehog, derived from the palatal epithelium. Treatment with p38 mitogen-activated protein kinase (MAPK) inhibitor or telmisartan, a modulator of p38 MAPK activation and lipid metabolism, blocked abnormal TGFβ-mediated p38 MAPK activation, restoring lipid metabolism and cell proliferation activity both in vitro and in vivo. Our results highlight the influence of alternative TGFβ signaling on lipid metabolic activities, as well as how lipid metabolic defects can affect cell proliferation and adversely impact palatogenesis. This discovery has broader implications for the understanding of metabolic defects and potential prevention of congenital birth defects. PMID:23975680

  12. Chemical Reporter for Visualizing Metabolic Cross-Talk between Carbohydrate Metabolism and Protein Modification

    PubMed Central

    2015-01-01

    Metabolic chemical reporters have been largely used to study posttranslational modifications. Generally, it was assumed that these reporters entered one biosynthetic pathway, resulting in labeling of one type of modification. However, because they are metabolized by cells before their addition onto proteins, metabolic chemical reporters potentially provide a unique opportunity to read-out on both modifications of interest and cellular metabolism. We report here the development of a metabolic chemical reporter 1-deoxy-N-pentynyl glucosamine (1-deoxy-GlcNAlk). This small-molecule cannot be incorporated into glycans; however, treatment of mammalian cells results in labeling of a variety proteins and enables their visualization and identification. Competition of this labeling with sodium acetate and an acetyltransferase inhibitor suggests that 1-deoxy-GlcNAlk can enter the protein acetylation pathway. These results demonstrate that metabolic chemical reporters have the potential to isolate and potentially discover cross-talk between metabolic pathways in living cells. PMID:25062036

  13. Modulation of opioid receptor function by protein-protein interactions.

    PubMed

    Alfaras-Melainis, Konstantinos; Gomes, Ivone; Rozenfeld, Raphael; Zachariou, Venetia; Devi, Lakshmi

    2009-01-01

    Opioid receptors, MORP, DORP and KORP, belong to the family A of G protein coupled receptors (GPCR), and have been found to modulate a large number of physiological functions, including mood, stress, appetite, nociception and immune responses. Exogenously applied opioid alkaloids produce analgesia, hedonia and addiction. Addiction is linked to alterations in function and responsiveness of all three opioid receptors in the brain. Over the last few years, a large number of studies identified protein-protein interactions that play an essential role in opioid receptor function and responsiveness. Here, we summarize interactions shown to affect receptor biogenesis and trafficking, as well as those affecting signal transduction events following receptor activation. This article also examines protein interactions modulating the rate of receptor endocytosis and degradation, events that play a major role in opiate analgesia. Like several other GPCRs, opioid receptors may form homo or heterodimers. The last part of this review summarizes recent knowledge on proteins known to affect opioid receptor dimerization. PMID:19273296

  14. Protein Quality Control and Metabolism: Bidirectional Control in the Heart

    PubMed Central

    Wang, Zhao V.; Hill, Joseph A.

    2015-01-01

    The prevalence of heart disease, especially heart failure, continues to increase, and cardiovascular disease remains the leading cause of death worldwide. As cardiomyocytes are essentially irreplaceable, protein quality control is pivotal to cellular homeostasis and, ultimately, cardiac performance. Three evolutionarily conserved mechanisms – autophagy, the unfolded protein response, and the ubiquitin-proteasome system– act in concert to degrade misfolded proteins and eliminate defective organelles. Recent advances have revealed that these mechanisms are intimately associated with cellular metabolism. Going forward, comprehensive understanding of the role of protein quality control mechanisms in cardiac pathology will require integration of metabolic pathways and metabolic control. PMID:25651176

  15. Pharmacological Modulators of Endoplasmic Reticulum Stress in Metabolic Diseases

    PubMed Central

    Jung, Tae Woo; Choi, Kyung Mook

    2016-01-01

    The endoplasmic reticulum (ER) is the principal organelle responsible for correct protein folding, a step in protein synthesis that is critical for the functional conformation of proteins. ER stress is a primary feature of secretory cells and is involved in the pathogenesis of numerous human diseases, such as certain neurodegenerative and cardiometabolic disorders. The unfolded protein response (UPR) is a defense mechanism to attenuate ER stress and maintain the homeostasis of the organism. Two major degradation systems, including the proteasome and autophagy, are involved in this defense system. If ER stress overwhelms the capacity of the cell’s defense mechanisms, apoptotic death may result. This review is focused on the various pharmacological modulators that can protect cells from damage induced by ER stress. The possible mechanisms for cytoprotection are also discussed. PMID:26840310

  16. Protein Phosphorylation: A Major Switch Mechanism for Metabolic Regulation.

    PubMed

    Humphrey, Sean J; James, David E; Mann, Matthias

    2015-12-01

    Metabolism research is undergoing a renaissance because many diseases are increasingly recognized as being characterized by perturbations in intracellular metabolic regulation. Metabolic changes can be conferred through changes to the expression of metabolic enzymes, the concentrations of substrates or products that govern reaction kinetics, or post-translational modification (PTM) of the proteins that facilitate these reactions. On the 60th anniversary since its discovery, reversible protein phosphorylation is widely appreciated as an essential PTM regulating metabolism. With the ability to quantitatively measure dynamic changes in protein phosphorylation on a global scale - hereafter referred to as phosphoproteomics - we are now entering a new era in metabolism research, with mass spectrometry (MS)-based proteomics at the helm. PMID:26498855

  17. Patterned optogenetic modulation of neurovascular and metabolic signals

    PubMed Central

    Richner, Thomas J; Baumgartner, Ryan; Brodnick, Sarah K; Azimipour, Mehdi; Krugner-Higby, Lisa A; Eliceiri, Kevin W; Williams, Justin C; Pashaie, Ramin

    2015-01-01

    The hemodynamic and metabolic response of the cortex depends spatially and temporally on the activity of multiple cell types. Optogenetics enables specific cell types to be modulated with high temporal precision and is therefore an emerging method for studying neurovascular and neurometabolic coupling. Going beyond temporal investigations, we developed a microprojection system to apply spatial photostimulus patterns in vivo. We monitored vascular and metabolic fluorescence signals after photostimulation in Thy1-channelrhodopsin-2 mice. Cerebral arteries increased in diameter rapidly after photostimulation, while nearby veins showed a slower smaller response. The amplitude of the arterial response was depended on the area of cortex stimulated. The fluorescence signal emitted at 450/100 nm and excited with ultraviolet is indicative of reduced nicotinamide adenine dinucleotide, an endogenous fluorescent enzyme involved in glycolysis and the citric acid cycle. This fluorescence signal decreased quickly and transiently after optogenetic stimulation, suggesting that glucose metabolism is tightly locked to optogenetic stimulation. To verify optogenetic stimulation of the cortex, we used a transparent substrate microelectrode array to map cortical potentials resulting from optogenetic stimulation. Spatial optogenetic stimulation is a new tool for studying neurovascular and neurometabolic coupling. PMID:25388678

  18. Network integration of parallel metabolic and transcriptional data reveals metabolic modules that regulate macrophage polarization.

    PubMed

    Jha, Abhishek K; Huang, Stanley Ching-Cheng; Sergushichev, Alexey; Lampropoulou, Vicky; Ivanova, Yulia; Loginicheva, Ekaterina; Chmielewski, Karina; Stewart, Kelly M; Ashall, Juliet; Everts, Bart; Pearce, Edward J; Driggers, Edward M; Artyomov, Maxim N

    2015-03-17

    Macrophage polarization involves a coordinated metabolic and transcriptional rewiring that is only partially understood. By using an integrated high-throughput transcriptional-metabolic profiling and analysis pipeline, we characterized systemic changes during murine macrophage M1 and M2 polarization. M2 polarization was found to activate glutamine catabolism and UDP-GlcNAc-associated modules. Correspondingly, glutamine deprivation or inhibition of N-glycosylation decreased M2 polarization and production of chemokine CCL22. In M1 macrophages, we identified a metabolic break at Idh, the enzyme that converts isocitrate to alpha-ketoglutarate, providing mechanistic explanation for TCA cycle fragmentation. (13)C-tracer studies suggested the presence of an active variant of the aspartate-arginosuccinate shunt that compensated for this break. Consistently, inhibition of aspartate-aminotransferase, a key enzyme of the shunt, inhibited nitric oxide and interleukin-6 production in M1 macrophages, while promoting mitochondrial respiration. This systems approach provides a highly integrated picture of the physiological modules supporting macrophage polarization, identifying potential pharmacologic control points for both macrophage phenotypes. PMID:25786174

  19. Type IV Pilin Proteins: Versatile Molecular Modules

    PubMed Central

    Giltner, Carmen L.; Nguyen, Ylan

    2012-01-01

    Summary: Type IV pili (T4P) are multifunctional protein fibers produced on the surfaces of a wide variety of bacteria and archaea. The major subunit of T4P is the type IV pilin, and structurally related proteins are found as components of the type II secretion (T2S) system, where they are called pseudopilins; of DNA uptake/competence systems in both Gram-negative and Gram-positive species; and of flagella, pili, and sugar-binding systems in the archaea. This broad distribution of a single protein family implies both a common evolutionary origin and a highly adaptable functional plan. The type IV pilin is a remarkably versatile architectural module that has been adopted widely for a variety of functions, including motility, attachment to chemically diverse surfaces, electrical conductance, acquisition of DNA, and secretion of a broad range of structurally distinct protein substrates. In this review, we consider recent advances in this research area, from structural revelations to insights into diversity, posttranslational modifications, regulation, and function. PMID:23204365

  20. GABAAergic stimulation modulates intracellular protein arginine methylation.

    PubMed

    Denman, Robert B; Xie, Wen; Merz, George; Sung, Ying-Ju

    2014-06-20

    Changes in cytoplasmic pH are known to regulate diverse cellular processes and influence neuronal activities. In neurons, the intracellular alkalization is shown to occur after stimulating several channels and receptors. For example, it has previously demonstrated in P19 neurons that a sustained intracellular alkalinization can be mediated by the Na(+)/H(+) antiporter. In addition, the benzodiazepine binding subtypes of the γ-amino butyric acid type A (GABAA) receptor mediate a transient intracellular alkalinization when they are stimulated. Because the activities of many enzymes are sensitive to pH shift, here we investigate the effects of intracellular pH modulation resulted from stimulating GABAA receptor on the protein arginine methyltransferases (PRMT) activities. We show that the major benzodiazepine subtype (2α1, 2β2, 1γ2) is constitutively expressed in both undifferentiated P19 cells and retinoic acid (RA) differentiated P19 neurons. Furthermore stimulation with diazepam and, diazepam plus muscimol produce an intracellular alkalinization that can be detected ex vivo with the fluorescence dye. The alkalinization results in significant perturbation in protein arginine methylation activity as measured in methylation assays with specific protein substrates. Altered protein arginine methylation is also observed when cells are treated with the GABAA agonist muscimol but not an antagonist, bicuculline. These data suggest that pH-dependent and pH-independent methylation pathways can be activated by GABAAergic stimulation, which we verified using hippocampal slice preparations from a mouse model of fragile X syndrome. PMID:24793772

  1. BCL-2 family proteins as regulators of mitochondria metabolism.

    PubMed

    Gross, Atan

    2016-08-01

    The BCL-2 family proteins are major regulators of apoptosis, and one of their major sites of action are the mitochondria. Mitochondria are the cellular hubs for metabolism and indeed selected BCL-2 family proteins also possess roles related to mitochondria metabolism and dynamics. Here we discuss the link between mitochondrial metabolism/dynamics and the fate of stem cells, with an emphasis on the role of the BID-MTCH2 pair in regulating this link. We also discuss the possibility that BCL-2 family proteins act as metabolic sensors/messengers coming on and off of mitochondria to "sample" the cytosol and provide the mitochondria with up-to-date metabolic information. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi. PMID:26827940

  2. Modulation of metabolic syndrome-related inflammation by cocoa.

    PubMed

    Gu, Yeyi; Lambert, Joshua D

    2013-06-01

    Cocoa (Theobroma cacao L., Sterculiaceae) is a widely consumed food ingredient. Although typically found in high-fat, high-sugar foods such as chocolate, cocoa is rich in polyphenols, methylxanthines, and monounsaturated fatty acids. There is increasing evidence that moderate consumption of cocoa and cocoa-containing foods may have beneficial effects on the health including vasodilatory, antioxidant, and anti-inflammatory effects. Polyphenols in cocoa, including monomeric flavanols, as well as polymeric proanthocyanidins, may play a role in these observed beneficial effects. Chronic inflammation represents a potential mechanistic link between obesity and its related pathologies: insulin resistance, dyslipidemia, and hypertension, which comprise the metabolic syndrome. In the present review, we discuss the available data regarding the modulation of metabolic syndrome-related inflammation by cocoa and cocoa-derived compounds. We emphasize studies using laboratory animals or human subjects since such studies often represent the strongest available evidence for biological effects. In vitro studies are included to provide some mechanistic context, but are critically interpreted. Although the available data seem to support the anti-inflammatory effects of cocoa, further studies are needed with regard to the dose-response relationship as well as the underlying mechanisms of action. We hope this review will stimulate further research on cocoa and its anti-inflammatory activities. PMID:23637048

  3. Inflammation, oxidative stress and metabolic syndrome: dietary modulation.

    PubMed

    Fernández-García, José C; Cardona, Fernando; Tinahones, Francisco J

    2013-11-01

    The metabolic syndrome (MetS) is a cluster of risk factors for the development of cardiovascular disease and type 2 diabetes mellitus. These risk factors include raised blood pressure, dyslipidemia (raised triglycerides and lowered high-density lipoprotein cholesterol), raised fasting glucose, and central obesity. MetS has become a serious public health and clinical problem whose prevalence and incidence are increasing along with the worldwide rise in rates of obesity and sedentary lifestyles. A number of studies have shown that MetS is associated with a state of low-grade inflammation, characterized by abnormal pro-inflammatory cytokine production, increased acute-phase reactants, and activation of a network of inflammatory signalling pathways. Moreover, MetS has also been linked to oxidative stress, a consequence of a reduction in the antioxidant systems and an increase in the production of reactive oxygen species. Nevertheless, agreement exists that dietary intervention may modulate the pro-inflammatory state and lessen oxidative stress related to MetS, thereby decreasing the cardiovascular risk. In this review we address the current available evidence regarding dietary modulation of inflammation and oxidative stress associated with MetS. PMID:24168441

  4. Protein and amino acid metabolism and requirements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteins are the major structural and functional components of all cells of the body. Enzymes, membrane carriers, blood transport molecules, intracellular matrix, and even hair and fingernails are proteins, as are many hormones. Proteins also constitute a major portion of all membranes, and the cons...

  5. Radioactive Lysine in Protein Metabolism Studies

    DOE R&D Accomplishments Database

    Miller, L. L.; Bale, W. F.; Yuile, C. L.; Masters, R. E.; Tishkoff, G. H.; Whipple,, G. H.

    1950-01-09

    Studies of incorporation of DL-lysine in various body proteins of the dog; the time course of labeled blood proteins; and apparent rate of disappearance of labeled plasma proteins for comparison of behavior of the plasma albumin and globulin fractions; shows more rapid turn over of globulin fraction.

  6. Leucine and protein metabolism in obese zucker rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Branched-chain amino acids (BCAAs) are circulating nutrient signals for protein accretion, however they increase in obesity and appear to prognosticate diabetes onset. To understand the mechanisms whereby obesity affects BCAAs and protein metabolism, we employed metabolomics and measured rates of [1...

  7. Modulation of phosphoinositide metabolism in aortic smooth muscle cells by allylamine

    SciTech Connect

    Cox, L.R.; Murphy, S.K.; Ramos, K. )

    1990-08-01

    Aortic smooth muscle cells (SMC) modulate from a contractile to a proliferative phenotype upon subchronic exposure to allylamine. The present studies were designed to determine if this phenotypic modulation is associated with alterations in the metabolism of membrane phosphoinositides. 32P incorporation into phosphatidylinositol 4-phosphate (PIP), phosphatidylinositol 4,5-bisphosphate (PIP2), and phosphatidic acid (PA) was lower by 31, 35, and 22%, respectively, in SMC from allylamine-treated animals relative to controls. In contrast, incorporation of (3H)myoinositol into inositol phosphates did not differ in allylamine cells relative to control cells. Exposure to dibutyryl (db) cAMP (0.2 mM) and theophylline (0.1 mM) reduced 32P incorporation into PIP and PIP2 in SMC from both experimental groups. Under these conditions, a decrease in (3H)myoinositol incorporation into inositol 1-phosphate was only observed in allylamine cells. The effects of db cAMP and theophylline in allylamine and control SMC correlated with a marked decrease in cellular proliferation. These results suggest that alterations in phosphoinositide synthesis and/or degradation contribute to the enhanced proliferation of SMC induced by allylamine. To further examine this concept, the effects of agents which modulate protein kinase C (PKC) activity were evaluated. Sphingosine (125-500 ng/ml), a PKC inhibitor, decreased SMC proliferation in allylamine, but not control cells. 12-O-Tetradecanoylphorbol-13-acetate (1-100 ng/ml), a PKC agonist, stimulated proliferation in control cells, but inhibited proliferation in cells from allylamine-treated animals. We conclude that allylamine-induced phenotypic modulation of SMC is associated with alterations in phosphoinositide metabolism.

  8. Can We Prevent Obesity-Related Metabolic Diseases by Dietary Modulation of the Gut Microbiota?

    PubMed

    Brahe, Lena K; Astrup, Arne; Larsen, Lesli H

    2016-01-01

    Obesity increases the risk of type 2 diabetes, cardiovascular diseases, and certain cancers, which are among the leading causes of death worldwide. Obesity and obesity-related metabolic diseases are characterized by specific alterations in the human gut microbiota. Experimental studies with gut microbiota transplantations in mice and in humans indicate that a specific gut microbiota composition can be the cause and not just the consequence of the obese state and metabolic disease, which suggests a potential for gut microbiota modulation in prevention and treatment of obesity-related metabolic diseases. In addition, dietary intervention studies have suggested that modulation of the gut microbiota can improve metabolic risk markers in humans, but a causal role of the gut microbiota in such studies has not yet been established. Here, we review and discuss the role of the gut microbiota in obesity-related metabolic diseases and the potential of dietary modulation of the gut microbiota in metabolic disease prevention and treatment. PMID:26773017

  9. The low density lipoprotein receptor modulates the effects of hypogonadism on diet-induced obesity and related metabolic perturbations

    PubMed Central

    Constantinou, Caterina; Mpatsoulis, Diogenis; Natsos, Anastasios; Petropoulou, Peristera-Ioanna; Zvintzou, Evangelia; Traish, Abdulmaged M.; Voshol, Peter J.; Karagiannides, Iordanes; Kypreos, Kyriakos E.

    2014-01-01

    Here, we investigated how LDL receptor deficiency (Ldlr−/−) modulates the effects of testosterone on obesity and related metabolic dysfunctions. Though sham-operated Ldlr−/− mice fed Western-type diet for 12 weeks became obese and showed disturbed plasma glucose metabolism and plasma cholesterol and TG profiles, castrated mice were resistant to diet-induced obesity and had improved glucose metabolism and reduced plasma TG levels, despite a further deterioration in their plasma cholesterol profile. The effect of hypogonadism on diet-induced weight gain of Ldlr−/− mice was independent of ApoE and Lrp1. Indirect calorimetry analysis indicated that hypogonadism in Ldlr−/− mice was associated with increased metabolic rate. Indeed, mitochondrial cytochrome c and uncoupling protein 1 expression were elevated, primarily in white adipose tissue, confirming increased mitochondrial metabolic activity due to thermogenesis. Testosterone replacement in castrated Ldlr−/− mice for a period of 8 weeks promoted diet-induced obesity, indicating a direct role of testosterone in the observed phenotype. Treatment of sham-operated Ldlr−/− mice with the aromatase inhibitor exemestane for 8 weeks showed that the obesity of castrated Ldlr−/− mice is independent of estrogens. Overall, our data reveal a novel role of Ldlr as functional modulator of metabolic alterations associated with hypogonadism. PMID:24837748

  10. Adjustments of Protein Metabolism in Fasting Arctic Charr, Salvelinus alpinus

    PubMed Central

    Cassidy, Alicia A.; Saulnier, Roxanne J.; Lamarre, Simon G.

    2016-01-01

    Protein metabolism, including the interrelated processes of synthesis and degradation, mediates the growth of an animal. In ectothermic animals, protein metabolism is responsive to changes in both biotic and abiotic conditions. This study aimed to characterise responses of protein metabolism to food deprivation that occur in the coldwater salmonid, Arctic charr, Salvelinus alpinus. We compared two groups of Arctic charr: one fed continuously and the other deprived of food for 36 days. We measured the fractional rate of protein synthesis (KS) in individuals from the fed and fasted groups using a flooding dose technique modified for the use of deuterium-labelled phenylalanine. The enzyme activities of the three major protein degradation pathways (ubiquitin proteasome, lysosomal cathepsins and the calpain systems) were measured in the same fish. This study is the first to measure both KS and the enzymatic activity of protein degradation in the same fish, allowing us to examine the apparent contribution of different protein degradation pathways to protein turnover in various tissues (red and white muscle, liver, heart and gills). KS was lower in the white muscle and in liver of the fasted fish compared to the fed fish. There were no observable effects of food deprivation on the protease activities in any of the tissues with the exception of liver, where the ubiquitin proteasome pathway seemed to be activated during fasting conditions. Lysosomal proteolysis appears to be the primary degradation pathway for muscle protein, while the ubiquitin proteasome pathway seems to predominate in the liver. We speculate that Arctic charr regulate protein metabolism during food deprivation to conserve proteins. PMID:27096948

  11. Co-evolution of metabolism and protein sequences.

    PubMed

    Schütte, Moritz; Klitgord, Niels; Segrè, Daniel; Ebenhöh, Oliver

    2010-01-01

    The set of chemicals producible and usable by metabolic pathways must have evolved in parallel with the enzymes that catalyze them. One implication of this common historical path should be a correspondence between the innovation steps that gradually added new metabolic reactions to the biosphere-level biochemical toolkit, and the gradual sequence changes that must have slowly shaped the corresponding enzyme structures. However, global signatures of a long-term co-evolution have not been identified. Here we search for such signatures by computing correlations between inter-reaction distances on a metabolic network, and sequence distances of the corresponding enzyme proteins. We perform our calculations using the set of all known metabolic reactions, available from the KEGG database. Reaction-reaction distance on the metabolic network is computed as the length of the shortest path on a projection of the metabolic network, in which nodes are reactions and edges indicate whether two reactions share a common metabolite, after removal of cofactors. Estimating the distance between enzyme sequences in a meaningful way requires some special care: for each enzyme commission (EC) number, we select from KEGG a consensus set of protein sequences using the cluster of orthologous groups of proteins (COG) database. We define the evolutionary distance between protein sequences as an asymmetric transition probability between two enzymes, derived from the corresponding pair-wise BLAST scores. By comparing the distances between sequences to the minimal distances on the metabolic reaction graph, we find a small but statistically significant correlation between the two measures. This suggests that the evolutionary walk in enzyme sequence space has locally mirrored, to some extent, the gradual expansion of metabolism. PMID:20238426

  12. Glucocorticoids and 11β-HSD1 are major regulators of intramyocellular protein metabolism.

    PubMed

    Morgan, Stuart A; Hassan-Smith, Zaki K; Doig, Craig L; Sherlock, Mark; Stewart, Paul M; Lavery, Gareth G

    2016-06-01

    The adverse metabolic effects of prescribed and endogenous glucocorticoid excess, 'Cushing's syndrome', create a significant health burden. While skeletal muscle atrophy and resultant myopathy is a clinical feature, the molecular mechanisms underpinning these changes are not fully defined. We have characterized the impact of glucocorticoids upon key metabolic pathways and processes regulating muscle size and mass including: protein synthesis, protein degradation, and myoblast proliferation in both murine C2C12 and human primary myotube cultures. Furthermore, we have investigated the role of pre-receptor modulation of glucocorticoid availability by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in these processes. Corticosterone (CORT) decreased myotube area, decreased protein synthesis, and increased protein degradation in murine myotubes. This was supported by decreased mRNA expression of insulin-like growth factor (IGF1), decreased activating phosphorylation of mammalian target of rapamycin (mTOR), decreased phosphorylation of 4E binding protein 1 (4E-BP1), and increased mRNA expression of key atrophy markers including: atrogin-1, forkhead box O3a (FOXO3a), myostatin (MSTN), and muscle-ring finger protein-1 (MuRF1). These findings were endorsed in human primary myotubes, where cortisol also decreased protein synthesis and increased protein degradation. The effects of 11-dehydrocorticosterone (11DHC) (in murine myotubes) and cortisone (in human myotubes) on protein metabolism were indistinguishable from that of CORT/cortisol treatments. Selective 11β-HSD1 inhibition blocked the decrease in protein synthesis, increase in protein degradation, and reduction in myotube area induced by 11DHC/cortisone. Furthermore, CORT/cortisol, but not 11DHC/cortisone, decreased murine and human myoblast proliferative capacity. Glucocorticoids are potent regulators of skeletal muscle protein homeostasis and myoblast proliferation. Our data underscores the potential use of

  13. Protein-dependent regulation of feeding and metabolism.

    PubMed

    Morrison, Christopher D; Laeger, Thomas

    2015-05-01

    Free-feeding animals often face complex nutritional choices that require the balancing of competing nutrients, but the mechanisms driving macronutrient-specific food intake are poorly defined. A large number of behavioral studies indicate that both the quantity and quality of dietary protein can markedly influence food intake and metabolism, and that dietary protein intake may be prioritized over energy intake. This review focuses on recent progress in defining the mechanisms underlying protein-specific feeding. Considering the evidence that protein powerfully regulates both food intake and metabolism, uncovering these protein-specific mechanisms may reveal new molecular targets for the treatment of obesity and diabetes while also offering a more complete understanding of how dietary factors shape both food intake and food choice. PMID:25771038

  14. Postexercise recovery period: carbohydrate and protein metabolism.

    PubMed

    Viru, A

    1996-02-01

    The essence of the postexercise recovery period is normalization of function and homeostatic equilibrium, and replenishment of energy resources and accomplishment of the reconstructive function. The repletion of energy stores is actualized in a certain sequence and followed by a transitory supercompensation. The main substrate for repletion of the muscle glycogen store is blood glucose derived from hepatic glucose output as well as from consumption of carbohydrates during the postexercise period. The repletion of liver glycogen is realized less rapidly. It depends to a certain extent on hepatic gluconeogenesis but mainly on supply with exogenous carbohydrates. The constructive function is founded on elevated protein turnover and adaptive protein synthesis. Whereas during and shortly after endurance exercise intensive protein breakdown was found in less active fast-twitch glycolytic fibers, during the later course of the recovery period the protein degradation rate increased together with intensification of protein synthesis rate in more active fast-twitch glycolytic oxidative and slow-twitch oxidative fibers. PMID:8680938

  15. Circadian Clocks as Modulators of Metabolic Comorbidity in Psychiatric Disorders.

    PubMed

    Barandas, Rita; Landgraf, Dominic; McCarthy, Michael J; Welsh, David K

    2015-12-01

    Psychiatric disorders such as schizophrenia, bipolar disorder, and major depressive disorder are often accompanied by metabolic dysfunction symptoms, including obesity and diabetes. Since the circadian system controls important brain systems that regulate affective, cognitive, and metabolic functions, and neuropsychiatric and metabolic diseases are often correlated with disturbances of circadian rhythms, we hypothesize that dysregulation of circadian clocks plays a central role in metabolic comorbidity in psychiatric disorders. In this review paper, we highlight the role of circadian clocks in glucocorticoid, dopamine, and orexin/melanin-concentrating hormone systems and describe how a dysfunction of these clocks may contribute to the simultaneous development of psychiatric and metabolic symptoms. PMID:26483181

  16. Root carbon and protein metabolism associated with heat tolerance.

    PubMed

    Huang, Bingru; Rachmilevitch, Shimon; Xu, Jichen

    2012-05-01

    Extensive past efforts have been taken toward understanding heat tolerance mechanisms of the aboveground organs. Root systems play critical roles in whole-plant adaptation to heat stress, but are less studied. This review discusses recent research results revealing some critical physiological and metabolic factors underlying root thermotolerance, with a focus on temperate perennial grass species. Comparative analysis of differential root responses to supraoptimal temperatures by a heat-adapted temperate C3 species, Agrostis scabra, which can survive high soil temperatures up to 45 °C in geothermal areas in Yellow Stone National Park, and a heat-sensitive cogeneric species, Agrostis stolonifera, suggested that efficient carbon and protein metabolism is critical for root thermotolerance. Superior root thermotolerance in a perennial grass was associated with a greater capacity to control respiratory costs through respiratory acclimation, lowering carbon investment in maintenance for protein turnover, and efficiently partitioning carbon into different metabolic pools and alternative respiration pathways. Proteomic analysis demonstrated that root thermotolerance was associated with an increased maintenance of stability and less degradation of proteins, particularly those important for metabolism and energy production. In addition, thermotolerant roots are better able to maintain growth and activity during heat stress by activating stress defence proteins such as those participating in antioxidant defence (i.e. superoxide dismutase, peroxidase, glutathione S-transferase) and chaperoning protection (i.e. heat shock protein). PMID:22328905

  17. Mutant p53 exerts oncogenic functions by modulating cancer cell metabolism

    PubMed Central

    Zhou, Ge; Myers, Jeffrey N

    2014-01-01

    The metabolic function of p53 is important for its oncosuppressive function. Mutant p53 (mutp53) with gain of oncogenic function can regulate cell metabolism. Our recent study revealed a novel transcription-independent mechanism for a gain-of-function mutp53 that directly inhibits activation of adenosine monophosphate-activated protein kinase (AMPK) to promote cancer cell metabolism. PMID:27308343

  18. Protein Acetylation and Acetyl Coenzyme A Metabolism in Budding Yeast

    PubMed Central

    Galdieri, Luciano; Zhang, Tiantian; Rogerson, Daniella; Lleshi, Rron

    2014-01-01

    Cells sense and appropriately respond to the physical conditions and availability of nutrients in their environment. This sensing of the environment and consequent cellular responses are orchestrated by a multitude of signaling pathways and typically involve changes in transcription and metabolism. Recent discoveries suggest that the signaling and transcription machineries are regulated by signals which are derived from metabolism and reflect the metabolic state of the cell. Acetyl coenzyme A (CoA) is a key metabolite that links metabolism with signaling, chromatin structure, and transcription. Acetyl-CoA is produced by glycolysis as well as other catabolic pathways and used as a substrate for the citric acid cycle and as a precursor in synthesis of fatty acids and steroids and in other anabolic pathways. This central position in metabolism endows acetyl-CoA with an important regulatory role. Acetyl-CoA serves as a substrate for lysine acetyltransferases (KATs), which catalyze the transfer of acetyl groups to the epsilon-amino groups of lysines in histones and many other proteins. Fluctuations in the concentration of acetyl-CoA, reflecting the metabolic state of the cell, are translated into dynamic protein acetylations that regulate a variety of cell functions, including transcription, replication, DNA repair, cell cycle progression, and aging. This review highlights the synthesis and homeostasis of acetyl-CoA and the regulation of transcriptional and signaling machineries in yeast by acetylation. PMID:25326522

  19. Impaired protein metabolism: interlinks between obesity, insulin resistance and inflammation.

    PubMed

    Guillet, C; Masgrau, A; Walrand, S; Boirie, Y

    2012-12-01

    Metabolic and structural changes in skeletal muscle that accompany obesity are often associated with the development of insulin resistance. The first events in the pathogenesis of this disorder are considered as an accumulation of lipids within skeletal muscle due to blunted muscle capacity to oxidize fatty acids. Fat infiltration is also associated with muscle fibre typology modification, decrease in muscle mass and impairments in muscle strength. Thus, as a result of obesity, mobility and quality of life are affected, and this is in part due to quantitative and qualitative impairments in skeletal muscle. In addition, the insulin resistance related to obesity results not only in defective insulin-stimulated glucose disposal but has also detrimental consequences on protein metabolism at the skeletal muscle level and whole-body level. This review highlights the involvement of fat accumulation and insulin resistance in metabolic disorders occurring in skeletal muscle during the development of obesity, and the impairments in the regulation of protein metabolism and protein turnover in the links between obesity, metabolic inflammation and insulin resistance. PMID:23107259

  20. The metabolically-modulated stem cell niche: a dynamic scenario regulating cancer cell phenotype and resistance to therapy

    PubMed Central

    Rovida, Elisabetta; Peppicelli, Silvia; Bono, Silvia; Bianchini, Francesca; Tusa, Ignazia; Cheloni, Giulia; Marzi, Ilaria; Cipolleschi, Maria Grazia; Calorini, Lido; Sbarba, Persio Dello

    2014-01-01

    This Perspective addresses the interactions of cancer stem cells (CSC) with environment which result in the modulation of CSC metabolism, and thereby of CSC phenotype and resistance to therapy. We considered first as a model disease chronic myeloid leukemia (CML), which is triggered by a well-identified oncogenetic protein (BCR/Abl) and brilliantly treated with tyrosine kinase inhibitors (TKi). However, TKi are extremely effective in inducing remission of disease, but unable, in most cases, to prevent relapse. We demonstrated that the interference with cell metabolism (oxygen/glucose shortage) enriches cells exhibiting the leukemia stem cell (LSC) phenotype and, at the same time, suppresses BCR/Abl protein expression. These LSC are therefore refractory to the TKi Imatinib-mesylate, pointing to cell metabolism as an important factor controlling the onset of TKi-resistant minimal residual disease (MRD) of CML and the related relapse. Studies of solid neoplasias brought another player into the control of MRD, low tissue pH, which often parallels cancer growth and progression. Thus, a 3-party scenario emerged for the regulation of CSC/LSC maintenance, MRD induction and disease relapse: the “hypoxic” versus the “ischemic” vs. the “acidic” environment. As these environments are unlikely constrained within rigid borders, we named this model the “metabolically-modulated stem cell niche.” PMID:25485495

  1. Vinpocetine modulates metabolic activity and function during retinal ischemia.

    PubMed

    Nivison-Smith, Lisa; O'Brien, Brendan J; Truong, Mai; Guo, Cindy X; Kalloniatis, Michael; Acosta, Monica L

    2015-05-01

    Vinpocetine protects against a range of degenerative conditions and insults of the central nervous system via multiple modes of action. Little is known, however, of its effects on metabolism. This may be highly relevant, as vinpocetine is highly protective against ischemia, a process that inhibits normal metabolic function. This study uses the ischemic retina as a model to characterize vinpocetine's effects on metabolism. Vinpocetine reduced the metabolic demand of the retina following ex vivo hypoxia and ischemia to normal levels based on lactate dehydrogenase activity. Vinpocetine delivered similar effects in an in vivo model of retinal ischemia-reperfusion, possibly through increasing glucose availability. Vinpocetine's effects on glucose also appeared to improve glutamate homeostasis in ischemic Müller cells. Other actions of vinpocetine following ischemia-reperfusion, such as reduced cell death and improved retinal function, were possibly a combination of the drug's actions on metabolism and other retinal pathways. Vinpocetine's metabolic effects appeared independent of its other known actions in ischemia, as it recovered retinal function in a separate metabolic model where the glutamate-to-glutamine metabolic pathway was inhibited in Müller cells. The results of this study indicate that vinpocetine mediates ischemic damage partly through altered metabolism and has potential beneficial effects as a treatment for ischemia of neuronal tissues. PMID:25696811

  2. Protein-Tyrosine Phosphatase 1B Substrates and Metabolic Regulation

    PubMed Central

    Bakke, Jesse; Haj, Fawaz G.

    2014-01-01

    Metabolic homeostasis requires integration of complex signaling networks which, when deregulated, contribute to metabolic syndrome and related disorders. Protein-tyrosine phosphatase 1B (PTP1B) has emerged as a key regulator of signaling networks that are implicated in metabolic diseases such as obesity and type 2 diabetes. In this review, we examine mechanisms that regulate PTP1B-substrate interaction, enzymatic activity and experimental approaches to identify PTP1B substrates. We then highlight findings that implicate PTP1B in metabolic regulation. In particular, insulin and leptin signaling are discussed as well as recently identified PTP1B substrates that are involved in endoplasmic reticulum stress response, cell-cell communication, energy balance and vesicle trafficking. In summary, PTP1B exhibits exquisite substrate specificity and is an outstanding pharmaceutical target for obesity and type 2 diabetes. PMID:25263014

  3. Modulating the gut flora alters amino acid metabolism in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Intestinal microbes consume and produce amino acids (AA). This may impact intestinal threonine (THR) metabolism necessary for adequate gut function. We hypothesized that modulating the gut flora results in an alteration of intestinal THR utilization and hence whole body AA metabolism. Neonatal pigs ...

  4. Protein and amino acid metabolism in the human newborn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Birth and adaptation to extrauterine life involve major shifts in the protein and energy metabolism of the human newborn. These include a shift from a state of continuous supply of nutrients including amino acids from the mother to cyclic periodic oral intake, a change in the redox state of organs, ...

  5. Towards Co-Evolution of Membrane Proteins and Metabolism

    NASA Astrophysics Data System (ADS)

    Wilson, Michael A.; Wei, Chenyu; Pohorille, Andrew

    2014-12-01

    Primordial metabolism co-evolved with the earliest membrane peptides to produce more environmentally fit progeny. Here, we map a continuous, evolutionary path that connects nascent biochemistry with simple, membrane-bound oligopeptides, ion channels and, further, membrane proteins capable of energy transduction and utilization of energy for active transport.

  6. Discovering Distinct Functional Modules of Specific Cancer Types Using Protein-Protein Interaction Networks

    PubMed Central

    Shen, Ru; Wang, Xiaosheng; Guda, Chittibabu

    2015-01-01

    Background. The molecular profiles exhibited in different cancer types are very different; hence, discovering distinct functional modules associated with specific cancer types is very important to understand the distinct functions associated with them. Protein-protein interaction networks carry vital information about molecular interactions in cellular systems, and identification of functional modules (subgraphs) in these networks is one of the most important applications of biological network analysis. Results. In this study, we developed a new graph theory based method to identify distinct functional modules from nine different cancer protein-protein interaction networks. The method is composed of three major steps: (i) extracting modules from protein-protein interaction networks using network clustering algorithms; (ii) identifying distinct subgraphs from the derived modules; and (iii) identifying distinct subgraph patterns from distinct subgraphs. The subgraph patterns were evaluated using experimentally determined cancer-specific protein-protein interaction data from the Ingenuity knowledgebase, to identify distinct functional modules that are specific to each cancer type. Conclusion. We identified cancer-type specific subgraph patterns that may represent the functional modules involved in the molecular pathogenesis of different cancer types. Our method can serve as an effective tool to discover cancer-type specific functional modules from large protein-protein interaction networks. PMID:26495282

  7. Processing incommensurately modulated protein diffraction data with Eval15

    SciTech Connect

    Porta, Jason; Lovelace, Jeffrey J.; Schreurs, Antoine M. M.; Kroon-Batenburg, Loes M. J.; Borgstahl, Gloria E. O.

    2011-07-01

    Data processing of an incommensurately modulated profilin–actin crystal is described. Recent challenges in biological X-ray crystallography include the processing of modulated diffraction data. A modulated crystal has lost its three-dimensional translational symmetry but retains long-range order that can be restored by refining a periodic modulation function. The presence of a crystal modulation is indicated by an X-ray diffraction pattern with periodic main reflections flanked by off-lattice satellite reflections. While the periodic main reflections can easily be indexed using three reciprocal-lattice vectors a*, b*, c*, the satellite reflections have a non-integral relationship to the main lattice and require a q vector for indexing. While methods for the processing of diffraction intensities from modulated small-molecule crystals are well developed, they have not been applied in protein crystallography. A recipe is presented here for processing incommensurately modulated data from a macromolecular crystal using the Eval program suite. The diffraction data are from an incommensurately modulated crystal of profilin–actin with single-order satellites parallel to b*. The steps taken in this report can be used as a guide for protein crystallographers when encountering crystal modulations. To our knowledge, this is the first report of the processing of data from an incommensurately modulated macromolecular crystal.

  8. Diet-Induced Metabolic Disturbances As Modulators of Brain Homeostasis

    PubMed Central

    Zhang, Le; Bruce-Keller, Annadora J.; Dasuri, Kalavathi; Nguyen, AnhThao; Liu, Dr Ying; Keller, Jeffrey N.

    2009-01-01

    A number of metabolic disturbances occur in response to the consumption of a high fat Western diet. Such metabolic disturbances can include the progressive development of hyperglycemia, hyperinsulemia, obesity, metabolic syndrome, and diabetes. Cumulatively, diet-induced disturbance in metabolism are known to promote increased morbidity and negatively impact life expectancy through a variety of mechanisms. While the impact of metabolic disturbances on the hepatic, endocrine, and cardiovascular systems are well established there remains a noticeable void in understanding the basis by which the central nervous system (CNS) becomes altered in response to diet-induced metabolic dysfunction. In particular, it remains to be fully elucidated which established features of diet-induced pathogenesis (observed in non-CNS tissues) are recapitulated in the brain, and identification as to whether the observed changes in the brain are a direct or indirect effect of peripheral metabolic disturbances. This review will focus on each of these key issues and identify some critical experimental questions which remain to be elucidated experimentally, as well as provide an outline of our current understanding for how diet-induced alterations in metabolism may impact the brain during aging and age-related diseases of the nervous system. PMID:18926905

  9. Transmitter and receiver modules in bacterial signaling proteins.

    PubMed Central

    Kofoid, E C; Parkinson, J S

    1988-01-01

    Prokaryotes are capable of sophisticated sensory behaviors. We have detected sequence motifs in bacterial signaling proteins that may act as transmitter or receiver modules in mediating protein-protein communication. These modules appear to retain their functional identities in many protein hosts, implying that they are structurally independent elements. We propose that the fundamental activity characterizing these domains is specific recognition and association of matched modules, accompanied by conformational changes in one or both of the interacting elements. Signal propagation is a natural consequence of this behavior. The versatility of this information-processing strategy is evident in the chemotaxis machinery of Escherichia coli, where proteins containing transmitters or receivers are linked in "dyadic relays" to form complex signaling networks. Images PMID:3293046

  10. Functional module identification in protein interaction networks by interaction patterns

    PubMed Central

    Wang, Yijie; Qian, Xiaoning

    2014-01-01

    Motivation: Identifying functional modules in protein–protein interaction (PPI) networks may shed light on cellular functional organization and thereafter underlying cellular mechanisms. Many existing module identification algorithms aim to detect densely connected groups of proteins as potential modules. However, based on this simple topological criterion of ‘higher than expected connectivity’, those algorithms may miss biologically meaningful modules of functional significance, in which proteins have similar interaction patterns to other proteins in networks but may not be densely connected to each other. A few blockmodel module identification algorithms have been proposed to address the problem but the lack of global optimum guarantee and the prohibitive computational complexity have been the bottleneck of their applications in real-world large-scale PPI networks. Results: In this article, we propose a novel optimization formulation LCP2 (low two-hop conductance sets) using the concept of Markov random walk on graphs, which enables simultaneous identification of both dense and sparse modules based on protein interaction patterns in given networks through searching for LCP2 by random walk. A spectral approximate algorithm SLCP2 is derived to identify non-overlapping functional modules. Based on a bottom-up greedy strategy, we further extend LCP2 to a new algorithm (greedy algorithm for LCP2) GLCP2 to identify overlapping functional modules. We compare SLCP2 and GLCP2 with a range of state-of-the-art algorithms on synthetic networks and real-world PPI networks. The performance evaluation based on several criteria with respect to protein complex prediction, high level Gene Ontology term prediction and especially sparse module detection, has demonstrated that our algorithms based on searching for LCP2 outperform all other compared algorithms. Availability and implementation: All data and code are available at http://www.cse.usf.edu/∼xqian/fmi/slcp2hop

  11. EFFECTS OF CONTINUOUS-WAVE, PULSED, AND SINUSOIDAL-AMPLITUDE-MODULATED MICROWAVES ON BRAIN ENERGY METABOLISM

    EPA Science Inventory

    A comparison of the effects of continuous wave, sinusoidal-amplitude modulated, and pulsed square-wave-modulated 591-MHz microwave exposures on brain energy metabolism was made in male Sprague Dawley rats (175-225g). Brain NADH fluorescence, adensine triphosphate (ATP) concentrat...

  12. Proteomic detection of proteins involved in perchlorate and chlorate metabolism.

    PubMed

    Bansal, Reema; Deobald, Lee A; Crawford, Ronald L; Paszczynski, Andrzej J

    2009-09-01

    Mass spectrometry and a time-course cell lysis method were used to study proteins involved in perchlorate and chlorate metabolism in pure bacterial cultures and environmental samples. The bacterial cultures used included Dechlorosoma sp. KJ, Dechloromonas hortensis, Pseudomonas chloritidismutans ASK-1, and Pseudomonas stutzeri. The environmental samples included an anaerobic sludge enrichment culture from a sewage treatment plant, a sample of a biomass-covered activated carbon matrix from a bioreactor used for treating perchlorate-contaminated drinking water, and a waste water effluent sample from a paper mill. The approach focused on detection of perchlorate (and chlorate) reductase and chlorite dismutase proteins, which are the two central enzymes in the perchlorate (or chlorate) reduction pathways. In addition, acetate-metabolizing enzymes in pure bacterial samples and housekeeping proteins from perchlorate (or chlorate)-reducing microorganisms in environmental samples were also identified. PMID:19199051

  13. [Review: plant polyphenols modulate lipid metabolism and related molecular mechanism].

    PubMed

    Dai, Yan-li; Zou, Yu-xiao; Liu, Fan; Li, Hong-zhi

    2015-11-01

    Lipid metabolism disorder is an important risk factor to obesity, hyperlipidemia and type 2 diabetes as well as other chronic metabolic disease. It is also a key target in preventing metabolic syndrome, chronic disease prevention. Plant polyphenol plays an important role in maintaining or improving lipid profile in a variety of ways. including regulating cholesterol absorption, inhibiting synthesis and secretion of triglyceride, and lowering plasma low density lipoprotein oxidation, etc. The purpose of this article is to review the lipid regulation effects of plant polyphenols and its related mechanisms. PMID:27071245

  14. Low Concentrations of Nitric Oxide Modulate Streptococcus pneumoniae Biofilm Metabolism and Antibiotic Tolerance.

    PubMed

    Allan, Raymond N; Morgan, Samantha; Brito-Mutunayagam, Sanjita; Skipp, Paul; Feelisch, Martin; Hayes, Stephen M; Hellier, William; Clarke, Stuart C; Stoodley, Paul; Burgess, Andrea; Ismail-Koch, Hasnaa; Salib, Rami J; Webb, Jeremy S; Faust, Saul N; Hall-Stoodley, Luanne

    2016-04-01

    Streptococcus pneumoniaeis one of the key pathogens responsible for otitis media (OM), the most common infection in children and the largest cause of childhood antibiotic prescription. Novel therapeutic strategies that reduce the overall antibiotic consumption due to OM are required because, although widespread pneumococcal conjugate immunization has controlled invasive pneumococcal disease, overall OM incidence has not decreased. Biofilm formation represents an important phenotype contributing to the antibiotic tolerance and persistence ofS. pneumoniaein chronic or recurrent OM. We investigated the treatment of pneumococcal biofilms with nitric oxide (NO), an endogenous signaling molecule and therapeutic agent that has been demonstrated to trigger biofilm dispersal in other bacterial species. We hypothesized that addition of low concentrations of NO to pneumococcal biofilms would improve antibiotic efficacy and that higher concentrations exert direct antibacterial effects. Unlike in many other bacterial species, low concentrations of NO did not result inS. pneumoniaebiofilm dispersal. Instead, treatment of bothin vitrobiofilms andex vivoadenoid tissue samples (a reservoir forS. pneumoniaebiofilms) with low concentrations of NO enhanced pneumococcal killing when combined with amoxicillin-clavulanic acid, an antibiotic commonly used to treat chronic OM. Quantitative proteomic analysis using iTRAQ (isobaric tag for relative and absolute quantitation) identified 13 proteins that were differentially expressed following low-concentration NO treatment, 85% of which function in metabolism or translation. Treatment with low-concentration NO, therefore, appears to modulate pneumococcal metabolism and may represent a novel therapeutic approach to reduce antibiotic tolerance in pneumococcal biofilms. PMID:26856845

  15. Uric acid as a modulator of glucose and lipid metabolism.

    PubMed

    Lima, William Gustavo; Martins-Santos, Maria Emília Soares; Chaves, Valéria Ernestânia

    2015-09-01

    In humans, uric acid is the final oxidation product of purine catabolism. The serum uric acid level is based on the balance between the absorption, production and excretion of purine. Uric acid is similarly produced in the liver, adipose tissue and muscle and is primarily excreted through the urinary tract. Several factors, including a high-fructose diet and the use of xenobiotics and alcohol, contribute to hyperuricaemia. Hyperuricaemia belongs to a cluster of metabolic and haemodynamic abnormalities, called metabolic syndrome, characterised by abdominal obesity, glucose intolerance, insulin resistance, dyslipidaemia and hypertension. Hyperuricaemia reduction in the Pound mouse or fructose-fed rats, as well as hyperuricaemia induction by uricase inhibition in rodents and studies using cell culture have suggested that uric acid plays an important role in the development of metabolic syndrome. These studies have shown that high uric acid levels regulate the oxidative stress, inflammation and enzymes associated with glucose and lipid metabolism, suggesting a mechanism for the impairment of metabolic homeostasis. Humans lacking uricase, the enzyme responsible for uric acid degradation, are susceptible to these effects. In this review, we summarise the current knowledge of the effects of uric acid on the regulation of metabolism, primarily focusing on liver, adipose tissue and skeletal muscle. PMID:26133655

  16. Metabolic Adaptation in Transplastomic Plants Massively Accumulating Recombinant Proteins

    PubMed Central

    Bally, Julia; Job, Claudette; Belghazi, Maya; Job, Dominique

    2011-01-01

    Background Recombinant chloroplasts are endowed with an astonishing capacity to accumulate foreign proteins. However, knowledge about the impact on resident proteins of such high levels of recombinant protein accumulation is lacking. Methodology/Principal Findings Here we used proteomics to characterize tobacco (Nicotiana tabacum) plastid transformants massively accumulating a p-hydroxyphenyl pyruvate dioxygenase (HPPD) or a green fluorescent protein (GFP). While under the conditions used no obvious modifications in plant phenotype could be observed, these proteins accumulated to even higher levels than ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), the most abundant protein on the planet. This accumulation occurred at the expense of a limited number of leaf proteins including Rubisco. In particular, enzymes involved in CO2 metabolism such as nuclear-encoded plastidial Calvin cycle enzymes and mitochondrial glycine decarboxylase were found to adjust their accumulation level to these novel physiological conditions. Conclusions/Significance The results document how protein synthetic capacity is limited in plant cells. They may provide new avenues to evaluate possible bottlenecks in recombinant protein technology and to maintain plant fitness in future studies aiming at producing recombinant proteins of interest through chloroplast transformation. PMID:21966485

  17. Myocardial Reloading After Extracorporeal Membrane Oxygenation Alters Substrate Metabolism While Promoting Protein Synthesis

    PubMed Central

    Kajimoto, Masaki; O'Kelly Priddy, Colleen M.; Ledee, Dolena R.; Xu, Chun; Isern, Nancy; Olson, Aaron K.; Rosiers, Christine Des; Portman, Michael A.

    2013-01-01

    Background Extracorporeal membrane oxygenation (ECMO) unloads the heart, providing a bridge to recovery in children after myocardial stunning. ECMO also induces stress which can adversely affect the ability to reload or wean the heart from the circuit. Metabolic impairments induced by altered loading and/or stress conditions may impact weaning. However, cardiac substrate and amino acid requirements upon weaning are unknown. We assessed the hypothesis that ventricular reloading with ECMO modulates both substrate entry into the citric acid cycle (CAC) and myocardial protein synthesis. Methods and Results Sixteen immature piglets (7.8 to 15.6 kg) were separated into 2 groups based on ventricular loading status: 8‐hour ECMO (UNLOAD) and postwean from ECMO (RELOAD). We infused into the coronary artery [2‐13C]‐pyruvate as an oxidative substrate and [13C6]‐L‐leucine as an indicator for amino acid oxidation and protein synthesis. Upon RELOAD, each functional parameter, which were decreased substantially by ECMO, recovered to near‐baseline level with the exclusion of minimum dP/dt. Accordingly, myocardial oxygen consumption was also increased, indicating that overall mitochondrial metabolism was reestablished. At the metabolic level, when compared to UNLOAD, RELOAD altered the contribution of various substrates/pathways to tissue pyruvate formation, favoring exogenous pyruvate versus glycolysis, and acetyl‐CoA formation, shifting away from pyruvate decarboxylation to endogenous substrate, presumably fatty acids. Furthermore, there was also a significant increase of tissue concentrations for all CAC intermediates (≈80%), suggesting enhanced anaplerosis, and of fractional protein synthesis rates (>70%). Conclusions RELOAD alters both cytosolic and mitochondrial energy substrate metabolism, while favoring leucine incorporation into protein synthesis rather than oxidation in the CAC. Improved understanding of factors governing these metabolic perturbations may

  18. Protein and leucine metabolism in maple syrup urine disease

    SciTech Connect

    Thompson, G.N.; Bresson, J.L.; Pacy, P.J.; Bonnefont, J.P.; Walter, J.H.; Leonard, J.V.; Saudubray, J.M.; Halliday, D. )

    1990-04-01

    Constant infusions of (13C)leucine and (2H5)phenylalanine were used to trace leucine and protein kinetics, respectively, in seven children with maple syrup urine disease (MSUD) and eleven controls matched for age and dietary protein intake. Despite significant elevations of plasma leucine (mean 351 mumol/l, range 224-477) in MSUD subjects, mean whole body protein synthesis (3.78 +/- 0.42 (SD) g.kg-1. 24 h-1) and catabolism (4.07 +/- 0.46) were similar to control values (3.69 +/- 0.50 and 4.09 +/- 0.50, respectively). The relationship between phenylalanine and leucine fluxes was also similar in MSUD subjects (mean phenylalanine-leucine flux ratio 0.35 +/- 0.07) and previously reported adult controls (0.33 +/- 0.02). Leucine oxidation was undetectable in four of the MSUD subjects and very low in the other three (less than 4 mumol.kg-1.h-1; controls 13-20). These results show that persistent elevation in leucine concentration has no effect on protein synthesis. The marked disturbance in leucine metabolism in MSUD did not alter the relationship between rates of catabolism of protein to phenylalanine and leucine, which provides further support for the validity of the use of a single amino acid to trace whole body protein metabolism. The minimal leucine oxidation in MSUD differs from findings in other inborn metabolic errors and indicates that in patients with classical MSUD there is no significant route of leucine disposal other than through protein synthesis.

  19. Alterations in protein metabolism during space flight and inactivity.

    PubMed

    Ferrando, Arny A; Paddon-Jones, Doug; Wolfe, Robert R

    2002-10-01

    Space flight and the accompanying diminished muscular activity lead to a loss of body nitrogen and muscle function. These losses may affect crew capabilities and health in long-duration missions. Space flight alters protein metabolism such that the body is unable to maintain protein synthetic rates. A concomitant hypocaloric intake and altered anabolic/catabolic hormonal profiles may contribute to or exacerbate this problem. The inactivity associated with bedrest also reduces muscle and whole-body protein synthesis. For this reason, bedrest provides a good model for the investigation of potential exercise and nutritional countermeasures to restore muscle protein synthesis. We have demonstrated that minimal resistance exercise preserves muscle protein synthesis throughout bedrest. In addition, ongoing work indicates that an essential amino acid and carbohydrate supplement may ameliorate the loss of lean body mass and muscle strength associated with 28 d of bedrest. The investigation of inactivity-induced alterations in protein metabolism, during space flight or prolonged bedrest, is applicable to clinical populations and, in a more general sense, to the problems associated with the decreased activity that occur with aging. PMID:12361775

  20. Alterations in protein metabolism during space flight and inactivity

    NASA Technical Reports Server (NTRS)

    Ferrando, Arny A.; Paddon-Jones, Doug; Wolfe, Robert R.

    2002-01-01

    Space flight and the accompanying diminished muscular activity lead to a loss of body nitrogen and muscle function. These losses may affect crew capabilities and health in long-duration missions. Space flight alters protein metabolism such that the body is unable to maintain protein synthetic rates. A concomitant hypocaloric intake and altered anabolic/catabolic hormonal profiles may contribute to or exacerbate this problem. The inactivity associated with bedrest also reduces muscle and whole-body protein synthesis. For this reason, bedrest provides a good model for the investigation of potential exercise and nutritional countermeasures to restore muscle protein synthesis. We have demonstrated that minimal resistance exercise preserves muscle protein synthesis throughout bedrest. In addition, ongoing work indicates that an essential amino acid and carbohydrate supplement may ameliorate the loss of lean body mass and muscle strength associated with 28 d of bedrest. The investigation of inactivity-induced alterations in protein metabolism, during space flight or prolonged bedrest, is applicable to clinical populations and, in a more general sense, to the problems associated with the decreased activity that occur with aging.

  1. Thyroid hormone’s role in regulating brain glucose metabolism and potentially modulating hippocampal cognitive processes

    PubMed Central

    Jahagirdar, V; McNay, EC

    2012-01-01

    Cognitive performance is dependent on adequate glucose supply to the brain. Insulin, which regulates systemic glucose metabolism, has been recently shown both to regulate hippocampal metabolism and to be a mandatory component of hippocampally-mediated cognitive performance. Thyroid hormones (TH) regulate systemic glucose metabolism and may also be involved in regulation of brain glucose metabolism. Here we review potential mechanisms for such regulation. Importantly, TH imbalance is often encountered in combination with metabolic disorders, such as diabetes, and may cause additional metabolic dysregulation and hence worsening of disease states. TH’s potential as a regulator of brain glucose metabolism is heightened by interactions with insulin signaling, but there have been relatively few studies on this topic or on the actions of TH in a mature brain. This review discusses evidence for mechanistic links between TH, insulin, cognitive function, and brain glucose metabolism, and suggests that TH is a good candidate to be a modulator of memory processes, likely at least in part by modulation of central insulin signaling and glucose metabolism. PMID:22437199

  2. Serotonin modulation of cerebral glucose metabolism: sex and age effects.

    PubMed

    Munro, Cynthia A; Workman, Clifford I; Kramer, Elisse; Hermann, Carol; Ma, Yilong; Dhawan, Vijay; Chaly, Thomas; Eidelberg, David; Smith, Gwenn S

    2012-11-01

    The serotonin system is implicated in a variety of psychiatric disorders whose clinical presentation and response to treatment differ between males and females, as well as with aging. However, human neurobiological studies are limited. Sex differences in the cerebral metabolic response to an increase in serotonin concentrations were measured, as well as the effect of aging, in men compared to women. Thirty-three normal healthy individuals (14 men/19 women, age range 20-79 years) underwent two resting positron emission tomography studies with the radiotracer [18F]-2-deoxy-2-fluoro-D-glucose ([(18)F]-FDG) after placebo and selective serotonin reuptake inhibitor (SSRI, citalopram) infusions on two separate days. Results indicated that women demonstrated widespread areas of increased cortical glucose metabolism with fewer areas of decrease in metabolism in response to citalopram. Men, in contrast, demonstrated several regions of decreased cortical metabolism, but no regions of increased metabolism. Age was associated with greater increases in women and greater decreases in men in most brain regions. These results support prior studies indicating that serotonin function differs in men and women across the lifespan. Future studies aimed at characterizing the influences of age and sex on the serotonin system in patients with psychiatric disorders are needed to elucidate the relationship between sex and age differences in brain chemistry and associated differences in symptom presentation and treatment response. PMID:22836227

  3. Retinoblastoma Protein Knockdown Favors Oxidative Metabolism and Glucose and Fatty Acid Disposal in Muscle Cells.

    PubMed

    Petrov, Petar D; Ribot, Joan; López-Mejía, Isabel C; Fajas, Lluís; Palou, Andreu; Bonet, M Luisa

    2016-03-01

    Deficiency in the retinoblastoma protein (Rb) favors leanness and a healthy metabolic profile in mice largely attributed to activation of oxidative metabolism in white and brown adipose tissues. Less is known about Rb modulation of skeletal muscle metabolism. This was studied here by transiently knocking down Rb expression in differentiated C2C12 myotubes using small interfering RNAs. Compared with control cells transfected with non-targeting RNAs, myotubes silenced for Rb (by 80-90%) had increased expression of genes related to fatty acid uptake and oxidation such as Cd36 and Cpt1b (by 61% and 42%, respectively), increased Mitofusin 2 protein content (∼2.5-fold increase), increased mitochondrial to nuclear DNA ratio (by 48%), increased oxygen consumption (by 65%) and decreased intracellular lipid accumulation. Rb silenced myotubes also displayed up-regulated levels of glucose transporter type 4 expression (∼5-fold increase), increased basal glucose uptake, and enhanced insulin-induced Akt phosphorylation. Interestingly, exercise in mice led to increased Rb phosphorylation (inactivation) in skeletal muscle as evidenced by immunohistochemistry analysis. In conclusion, the silencing of Rb enhances mitochondrial oxidative metabolism and fatty acid and glucose disposal in skeletal myotubes, and changes in Rb status may contribute to muscle physiological adaptation to exercise. PMID:26241807

  4. Module-based functional pathway enrichment analysis of a protein-protein interaction network to study the effects of intestinal microbiota depletion in mice

    PubMed Central

    JIA, ZHEN-YI; XIA, YANG; TONG, DANIAN; YAO, JING; CHEN, HONG-QI; YANG, JUN

    2014-01-01

    Complex communities of microorganisms play important roles in human health, and alterations in the intestinal microbiota may induce intestinal inflammation and numerous diseases. The purpose of this study was to identify the key genes and processes affected by depletion of the intestinal microbiota in a murine model. The Affymetrix microarray dataset GSE22648 was downloaded from the Gene Expression Omnibus database, and differentially expressed genes (DEGs) were identified using the limma package in R. A protein-protein interaction (PPI) network was constructed for the DEGs using the Cytoscape software, and the network was divided into several modules using the MCODE plugin. Furthermore, the modules were functionally annotated using the PiNGO plugin, and DEG-related pathways were retrieved and analyzed using the GenMAPP software. A total of 53 DEGs were identified, of which 26 were upregulated and 27 were downregulated. The PPI network of these DEGs comprised 3 modules. The most significant module-related DEGs were the cytochrome P450 (CYP) 4B1 isozyme gene (CYP4B1) in module 1, CYP4F14 in module 2 and the tachykinin precursor 1 gene (TAC1) in module 3. The majority of enriched pathways of module 1 and 2 were oxidation reduction pathways (metabolism of xenobiotics by CYPs) and lipid metabolism-related pathways, including linoleic acid and arachidonic acid metabolism. The neuropeptide signaling pathway was the most significantly enriched functional pathway of module 3. In conclusion, our findings strongly suggest that intestinal microbiota depletion affects cellular metabolism and oxidation reduction pathways. In addition, this is the first time, to the best of our knowledge, that the neuropeptide signaling pathway is reported to be affected by intestinal microbiota depletion in mice. The present study provides a list of candidate genes and processes related to the interaction of microbiota with the intestinal tract. PMID:24718810

  5. Module-based functional pathway enrichment analysis of a protein-protein interaction network to study the effects of intestinal microbiota depletion in mice.

    PubMed

    Jia, Zhen-Yi; Xia, Yang; Tong, Danian; Yao, Jing; Chen, Hong-Qi; Yang, Jun

    2014-06-01

    Complex communities of microorganisms play important roles in human health, and alterations in the intestinal microbiota may induce intestinal inflammation and numerous diseases. The purpose of this study was to identify the key genes and processes affected by depletion of the intestinal microbiota in a murine model. The Affymetrix microarray dataset GSE22648 was downloaded from the Gene Expression Omnibus database, and differentially expressed genes (DEGs) were identified using the limma package in R. A protein-protein interaction (PPI) network was constructed for the DEGs using the Cytoscape software, and the network was divided into several modules using the MCODE plugin. Furthermore, the modules were functionally annotated using the PiNGO plugin, and DEG-related pathways were retrieved and analyzed using the GenMAPP software. A total of 53 DEGs were identified, of which 26 were upregulated and 27 were downregulated. The PPI network of these DEGs comprised 3 modules. The most significant module-related DEGs were the cytochrome P450 (CYP) 4B1 isozyme gene (CYP4B1) in module 1, CYP4F14 in module 2 and the tachykinin precursor 1 gene (TAC1) in module 3. The majority of enriched pathways of module 1 and 2 were oxidation reduction pathways (metabolism of xenobiotics by CYPs) and lipid metabolism-related pathways, including linoleic acid and arachidonic acid metabolism. The neuropeptide signaling pathway was the most significantly enriched functional pathway of module 3. In conclusion, our findings strongly suggest that intestinal microbiota depletion affects cellular metabolism and oxidation reduction pathways. In addition, this is the first time, to the best of our knowledge, that the neuropeptide signaling pathway is reported to be affected by intestinal microbiota depletion in mice. The present study provides a list of candidate genes and processes related to the interaction of microbiota with the intestinal tract. PMID:24718810

  6. The Involvement of Transport Proteins in Transcriptional and Metabolic Regulation

    PubMed Central

    Västermark, Åke; Saier, Milton H.

    2014-01-01

    Transport proteins have sometimes gained secondary regulatory functions that influence gene expression and metabolism. These functions allow communication with the external world via mechanistically distinctive signal transduction pathways. In this brief review we focus on three transport systems in Escherichia coli that control and coordinate carbon, exogenous hexose-phosphate and phosphorous metabolism. The transport proteins that play central roles in these processes are (1) the phosphoenolpyruvate (PEP)-dependent phosphotransferase system, PTS, (2) the glucose-6-phosphate receptor, UhpC, and (3) the phosphate-specific transporter, PstSABC, respectively. While the PTS participates in multiple complex regulatory processes, three of which are discussed here, UhpC and the Pst transporters exemplify differing strategies. PMID:24513656

  7. Expression data on liver metabolic pathway genes and proteins

    PubMed Central

    Raja Gopal Reddy, Mooli; Pavan Kumar, Chodisetti; Mahesh, Malleswarapu; Sravan Kumar, Manchiryala; Jeyakumar, Shanmugam M.

    2016-01-01

    Here, we present the expression data on various metabolic pathways of liver with special emphasize on lipid and carbohydrate metabolism and long chain polyunsaturated fatty acid (PUFA) synthesis, both at gene and protein levels. The data were obtained to understand the effect of vitamin A deficiency on the expression status (both gene and protein levels) of some of the key factors involved in lipogenesis, fatty acid oxidation, triglyceride secretion, long chain PUFA, resolvin D1 synthesis, glucose transport and glycogen synthesis of liver, using modern biology tools, such as quantitative real-time PCR (RT-PCR) and immunoblotting techniques. This data article provides the supporting evidence to the article “Vitamin A deficiency suppresses high fructose-induced triglyceride synthesis and elevates resolvin D1 levels” [1] and therefore, these data may be referred back, for comprehensive understanding and interpretations and for future studies. PMID:26909377

  8. Role of acetylcholinesterase inhibitors in the metabolism of amyloid precursor protein.

    PubMed

    Pakaski, M; Kasa, P

    2003-06-01

    Potentiation of central cholinergic activity has been proposed as a therapeutic approach for improving the cognitive function in patients with Alzheimer's disease (AD). Increasing the acetylcholine concentration in the brain by modulating acetylcholine-sterase (AChE) activity is among the most promising therapeutic strategies. Efforts to treat the underlying pathology based on the modulation of amyloid precursor protein (APP) processing in order to decrease the accumulation of beta-amyloid are also very important. Alterations in APP metabolism have recently been proposed to play a key role in the long-lasting effects of AChE inhibitors. This review surveys recent data from in vivo and in vitro studies that have contributed to our understanding of the role of AChE inhibitors in APP processing. The regulatory mechanisms relating to the muscarinic agonist effect, protein kinase C activation and mitogen-activated protein kinase phosphorylation, involving the alpha-secretase or the 5 -UTR region of the APP gene, are also discussed. Further work is warranted to elucidate the exact roles in APP metabolism of the AChE inhibitors used in AD therapy at present. PMID:12769797

  9. Dimethyl fumarate modulates antioxidant and lipid metabolism in oligodendrocytes.

    PubMed

    Huang, He; Taraboletti, Alexandra; Shriver, Leah P

    2015-08-01

    Oxidative stress contributes to pathology associated with inflammatory brain disorders and therapies that upregulate antioxidant pathways may be neuroprotective in diseases such as multiple sclerosis. Dimethyl fumarate, a small molecule therapeutic for multiple sclerosis, activates cellular antioxidant signaling pathways and may promote myelin preservation. However, it is still unclear what mechanisms may underlie this neuroprotection and whether dimethyl fumarate affects oligodendrocyte responses to oxidative stress. Here, we examine metabolic alterations in oligodendrocytes treated with dimethyl fumarate by using a global metabolomic platform that employs both hydrophilic interaction liquid chromatography-mass spectrometry and shotgun lipidomics. Prolonged treatment of oligodendrocytes with dimethyl fumarate induces changes in citric acid cycle intermediates, glutathione, and lipids, indicating that this compound can directly impact oligodendrocyte metabolism. These metabolic alterations are also associated with protection from oxidant challenge. This study provides insight into the mechanisms by which dimethyl fumarate could preserve myelin integrity in patients with multiple sclerosis. PMID:25967672

  10. Size matters: plasticity in metabolic scaling shows body-size may modulate responses to climate change.

    PubMed

    Carey, Nicholas; Sigwart, Julia D

    2014-08-01

    Variability in metabolic scaling in animals, the relationship between metabolic rate ( R: ) and body mass ( M: ), has been a source of debate and controversy for decades. R: is proportional to MB: , the precise value of B: much debated, but historically considered equal in all organisms. Recent metabolic theory, however, predicts B: to vary among species with ecology and metabolic level, and may also vary within species under different abiotic conditions. Under climate change, most species will experience increased temperatures, and marine organisms will experience the additional stressor of decreased seawater pH ('ocean acidification'). Responses to these environmental changes are modulated by myriad species-specific factors. Body-size is a fundamental biological parameter, but its modulating role is relatively unexplored. Here, we show that changes to metabolic scaling reveal asymmetric responses to stressors across body-size ranges; B: is systematically decreased under increasing temperature in three grazing molluscs, indicating smaller individuals were more responsive to warming. Larger individuals were, however, more responsive to reduced seawater pH in low temperatures. These alterations to the allometry of metabolism highlight abiotic control of metabolic scaling, and indicate that responses to climate warming and ocean acidification may be modulated by body-size. PMID:25122741

  11. Total Cellular RNA Modulates Protein Activity.

    PubMed

    Majumder, Subhabrata; DeMott, Christopher M; Reverdatto, Sergey; Burz, David S; Shekhtman, Alexander

    2016-08-16

    RNA constitutes up to 20% of a cell's dry weight, corresponding to ∼20 mg/mL. This high concentration of RNA facilitates low-affinity protein-RNA quinary interactions, which may play an important role in facilitating and regulating biological processes. In the yeast Pichia pastoris, the level of ubiquitin-RNA colocalization increases when cells are grown in the presence of dextrose and methanol instead of methanol as the sole carbon source. Total RNA isolated from cells grown in methanol increases β-galactosidase activity relative to that seen with RNA isolated from cells grown in the presence of dextrose and methanol. Because the total cellular RNA content changes with growth medium, protein-RNA quinary interactions can alter in-cell protein biochemistry and may play an important role in cell adaptation, critical to many physiological and pathological states. PMID:27456029

  12. Modulation of lipoprotein metabolism by antisense technology: preclinical drug discovery methodology.

    PubMed

    Crooke, Rosanne M; Graham, Mark J

    2013-01-01

    Antisense oligonucleotides (ASOs) are a new class of specific therapeutic agents that alter the intermediary metabolism of mRNA, resulting in the suppression of disease-associated gene products. ASOs exert their pharmacological effects after hybridizing, via Watson-Crick base pairing, to a specific target RNA. If appropriately designed, this event results in the recruitment of RNase H, the degradation of targeted mRNA or pre-mRNA, and subsequent inhibition of the synthesis of a specific protein. A key advantage of the technology is the ability to selectively inhibit targets that cannot be modulated by traditional therapeutics such as structural proteins, transcription factors, and, of topical interest, lipoproteins. In this chapter, we will first provide an overview of antisense technology, then more specifically describe the status of lipoprotein-related genes that have been studied using the antisense platform, and finally, outline the general methodology required to design and evaluate the in vitro and in vivo efficacy of those drugs. PMID:23912993

  13. Perilipin-related protein regulates lipid metabolism in C. elegans

    PubMed Central

    Chughtai, Ahmed Ali; Kaššák, Filip; Kostrouchová, Markéta; Novotný, Jan Philipp; Krause, Michael W.; Kostrouch, Zdenek

    2015-01-01

    Perilipins are lipid droplet surface proteins that contribute to fat metabolism by controlling the access of lipids to lipolytic enzymes. Perilipins have been identified in organisms as diverse as metazoa, fungi, and amoebas but strikingly not in nematodes. Here we identify the protein encoded by the W01A8.1 gene in Caenorhabditis elegans as the closest homologue and likely orthologue of metazoan perilipin. We demonstrate that nematode W01A8.1 is a cytoplasmic protein residing on lipid droplets similarly as human perilipins 1 and 2. Downregulation or elimination of W01A8.1 affects the appearance of lipid droplets resulting in the formation of large lipid droplets localized around the dividing nucleus during the early zygotic divisions. Visualization of lipid containing structures by CARS microscopy in vivo showed that lipid-containing structures become gradually enlarged during oogenesis and relocate during the first zygotic division around the dividing nucleus. In mutant embryos, the lipid containing structures show defective intracellular distribution in subsequent embryonic divisions and become gradually smaller during further development. In contrast to embryos, lipid-containing structures in enterocytes and in epidermal cells of adult animals are smaller in mutants than in wild type animals. Our results demonstrate the existence of a perilipin-related regulation of fat metabolism in nematodes and provide new possibilities for functional studies of lipid metabolism. PMID:26357594

  14. Myocardial Reloading after Extracorporeal Membrane Oxygenation Alters Substrate Metabolism While Promoting Protein Synthesis

    SciTech Connect

    Kajimoto, Masaki; Priddy, Colleen M.; Ledee, Dolena; Xu, Chun; Isern, Nancy G.; Olson, Aaron; Des Rosiers, Christine; Portman, Michael A.

    2013-08-19

    Extracorporeal membrane oxygenation (ECMO) unloads the heart providing a bridge to recovery in children after myocardial stunning. Mortality after ECMO remains high.Cardiac substrate and amino acid requirements upon weaning are unknown and may impact recovery. We assessed the hypothesis that ventricular reloading modulates both substrate entry into the citric acid cycle (CAC) and myocardial protein synthesis. Fourteen immature piglets (7.8-15.6 kg) were separated into 2 groups based on ventricular loading status: 8 hour-ECMO (UNLOAD) and post-wean from ECMO (RELOAD). We infused [2-13C]-pyruvate as an oxidative substrate and [13C6]-L-leucine, as a tracer of amino acid oxidation and protein synthesis into the coronary artery. RELOAD showed marked elevations in myocardial oxygen consumption above baseline and UNLOAD. Pyruvate uptake was markedly increased though RELOAD decreased pyruvate contribution to oxidative CAC metabolism.RELOAD also increased absolute concentrations of all CAC intermediates, while maintaining or increasing 13C-molar percent enrichment. RELOAD also significantly increased cardiac fractional protein synthesis rates by >70% over UNLOAD. Conclusions: RELOAD produced high energy metabolic requirement and rebound protein synthesis. Relative pyruvate decarboxylation decreased with RELOAD while promoting anaplerotic pyruvate carboxylation and amino acid incorporation into protein rather than to the CAC for oxidation. These perturbations may serve as therapeutic targets to improve contractile function after ECMO.

  15. Ethanol impairs post-prandial hepatic protein metabolism.

    PubMed Central

    De Feo, P; Volpi, E; Lucidi, P; Cruciani, G; Monacchia, F; Reboldi, G; Santeusanio, F; Bolli, G B; Brunetti, P

    1995-01-01

    The effects of acute ethanol ingestion on whole body and hepatic protein metabolism in humans are not known. To simulate social drinking, we compared the effects of the association of a mixed meal (632 kcal, 17% amino acids, 50% glucose, 33% lipids) with a bottle of either table wine (ethanol content 71 g) or water on the estimates ([1-14C]-leucine infusion) of whole body protein breakdown, oxidation, and synthesis, and on the intravascular fractional secretory rates (FSR) of hepatically (albumin, fibrinogen) and extrahepatically (IgG) synthesized plasma proteins in two randomized groups (ethanol n = 7, water n = 7) of healthy nonalcoholic volunteers. Each study was carried out for 8 h. Protein kinetics were measured in the overnight post-absorptive state, over the first 4 h, and during a meal infusion (via a nasogastric feeding tube at constant rate) combined with the oral ingestion of wine or water, over the last 4 h. When compared with water, wine ingestion during the meal reduced (P < 0.03) by 24% the rate of leucine oxidation, did not modify the estimates of whole body protein breakdown and synthesis, reduced (P < 0.01) by approximately 30% the FSR of albumin and fibrinogen, but did not affect IgG FSR. In conclusion, 70 g of ethanol, an amount usual among social drinkers, impairs hepatic protein metabolism. The habitual consumption of such amounts by reducing the synthesis and/or secretion of hepatic proteins might lead to the progressive development of liver injury and to hypoalbuminemia also in the absence of protein malnutrition. PMID:7706451

  16. Metabolism and mis-metabolism of the neuropathological signature protein TDP-43.

    PubMed

    Huang, Chi-Chen; Bose, Jayarama Krishnan; Majumder, Pritha; Lee, Kuen-Haur; Huang, Jen-Tse Joseph; Huang, Jeffrey K; Shen, Che-Kun James

    2014-07-15

    TDP-43 (also known as TARDBP) is a pathological signature protein of neurodegenerative diseases, with TDP-43 proteinopathies including frontotemporal lobar degeneration (FTLD)-TDP and amyotrophic lateral sclerosis (ALS)-TDP. These TDP-43 proteinopathies are characterized by cytoplasmic insoluble TDP-43-positive aggregates in the diseased cells, the formation of which requires the seeding of TDP-25 fragment generated by caspase cleavage of TDP-43. We have investigated the metabolism and mis-metabolism of TDP-43 in cultured cells and found that endogenous and exogenously overexpressed TDP-43 is degraded not only by the ubiquitin proteasome system (UPS) and macroautophagy, but also by the chaperone-mediated autophagy (CMA) mediated through an interaction between Hsc70 (also known as HSPA8) and ubiquitylated TDP-43. Furthermore, proteolytic cleavage of TDP-43 by caspase(s) is a necessary intermediate step for degradation of the majority of the TDP-43 protein, with the TDP-25 and TDP-35 fragments being the main substrates. Finally, we have determined the threshold level of the TDP-25 fragment that is necessary for formation of the cytosolic TDP-43-positive aggregates in cells containing the full-length TDP-43 at an elevated level close to that found in patients with TDP-43 proteinopathies. A comprehensive model of the metabolism and mis-metabolism of TDP-43 in relation to these findings is presented. PMID:24860144

  17. Tumor microenvironment derived exosomes pleiotropically modulate cancer cell metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cancer-associated fibroblasts (CAFs) are a major cellular component of tumor microenvironment in most solid cancers. Altered cellular metabolism is a hallmark of cancer, and much of the published literature has focused on neoplastic cell-autonomous processes for these adaptations. We demonstrate tha...

  18. Dopamine Modulates Metabolic Rate and Temperature Sensitivity in Drosophila melanogaster

    PubMed Central

    Ueno, Taro; Tomita, Jun; Kume, Shoen; Kume, Kazuhiko

    2012-01-01

    Homeothermal animals, such as mammals, maintain their body temperature by heat generation and heat dissipation, while poikilothermal animals, such as insects, accomplish it by relocating to an environment of their favored temperature. Catecholamines are known to regulate thermogenesis and metabolic rate in mammals, but their roles in other animals are poorly understood. The fruit fly, Drosophila melanogaster, has been used as a model system for the genetic studies of temperature preference behavior. Here, we demonstrate that metabolic rate and temperature sensitivity of some temperature sensitive behaviors are regulated by dopamine in Drosophila. Temperature-sensitive molecules like dTrpA1 and shits induce temperature-dependent behavioral changes, and the temperature at which the changes are induced were lowered in the dopamine transporter-defective mutant, fumin. The mutant also displays a preference for lower temperatures. This thermophobic phenotype was rescued by the genetic recovery of the dopamine transporter in dopamine neurons. Flies fed with a dopamine biosynthesis inhibitor (3-iodo-L-tyrosine), which diminishes dopamine signaling, exhibited preference for a higher temperature. Furthermore, we found that the metabolic rate is up-regulated in the fumin mutant. Taken together, dopamine has functions in the temperature sensitivity of behavioral changes and metabolic rate regulation in Drosophila, as well as its previously reported functions in arousal/sleep regulation. PMID:22347491

  19. Engineering and Assembly of Protein Modules into Functional Molecular Systems.

    PubMed

    Hirschi, Stephan; Stauffer, Mirko; Harder, Daniel; Müller, Daniel J; Meier, Wolfgang; Fotiadis, Dimitrios

    2016-01-01

    Synthetic biology approaches range from the introduction of unique features into organisms to the assembly of isolated biomacromolecules or synthetic building blocks into artificial biological systems with biomimetic or completely novel functionalities. Simple molecular systems can be based on containers on the nanoscale that are equipped with tailored functional modules for various applications in healthcare, industry or biological and medical research. The concept, or vision, of assembling native or engineered proteins and/or synthetic components as functional modules into molecular systems is discussed. The main focus is laid on the engineering of energizing modules generating chemical energy, transport modules using this energy to translocate molecules between compartments of a molecular system, and catalytic modules (bio-)chemically processing the molecules. Further key aspects of this discourse are possible approaches for the assembly of simple nanofactories and their applications in biotechnology and medical health. PMID:27363367

  20. Bofu-tsu-shosan, an oriental herbal medicine, exerts a combinatorial favorable metabolic modulation including antihypertensive effect on a mouse model of human metabolic disorders with visceral obesity.

    PubMed

    Azushima, Kengo; Tamura, Kouichi; Wakui, Hiromichi; Maeda, Akinobu; Ohsawa, Masato; Uneda, Kazushi; Kobayashi, Ryu; Kanaoka, Tomohiko; Dejima, Toru; Fujikawa, Tetsuya; Yamashita, Akio; Toya, Yoshiyuki; Umemura, Satoshi

    2013-01-01

    Accumulating evidence indicates that metabolic dysfunction with visceral obesity is a major medical problem associated with the development of hypertension, type 2 diabetes (T2DM) and dyslipidemia, and ultimately severe cardiovascular and renal disease. Therefore, an effective anti-obesity treatment with a concomitant improvement in metabolic profile is important for the treatment of metabolic dysfunction with visceral obesity. Bofu-tsu-shosan (BOF) is one of oriental herbal medicine and is clinically available to treat obesity in Japan. Although BOF is a candidate as a novel therapeutic strategy to improve metabolic dysfunction with obesity, the mechanism of its beneficial effect is not fully elucidated. Here, we investigated mechanism of therapeutic effects of BOF on KKAy mice, a model of human metabolic disorders with obesity. Chronic treatment of KKAy mice with BOF persistently decreased food intake, body weight gain, low-density lipoprotein cholesterol and systolic blood pressure. In addition, both tissue weight and cell size of white adipose tissue (WAT) were decreased, with concomitant increases in the expression of adiponectin and peroxisome proliferator-activated receptors genes in WAT as well as the circulating adiponectin level by BOF treatment. Furthermore, gene expression of uncoupling protein-1, a thermogenesis factor, in brown adipose tissue and rectal temperature were both elevated by BOF. Intriguingly, plasma acylated-ghrelin, an active form of orexigenic hormone, and short-term food intake were significantly decreased by single bolus administration of BOF. These results indicate that BOF exerts a combinatorial favorable metabolic modulation including antihypertensive effect, at least partially, via its beneficial effect on adipose tissue function and its appetite-inhibitory property through suppression on the ghrelin system. PMID:24130717

  1. New insights on hormones and factors that modulate Sertoli cell metabolism.

    PubMed

    Rato, Luís; Meneses, Maria João; Silva, Branca M; Sousa, Mário; Alves, Marco G; Oliveira, Pedro F

    2016-05-01

    Sertoli cells (SCs) play a key role in spermatogenesis by providing the physical support for developing germ cells and ensuring them the appropriate nutrients, energy sources, hormones, and growth factors. The control of SCs metabolism has been in the spotlight for reproductive biologists, since it may be crucial to determine germ cells' fate. Indeed, the maintenance of spermatogenesis is highly dependent on the metabolic cooperation established between SCs and germ cells, though this event has been overlooked. It depends on the orchestration of various metabolic pathways and an intricate network of signals. Several factors and/or hormones modulate the metabolic activity of SCs, which are major targets for the hormonal signalling that regulates spermatogenesis. Any alteration in the regulation of these cells' metabolic behaviour may compromise the normal development of spermatogenesis and consequently, male fertility. In this context, SC metabolism arises as a key regulation point for spermatogenesis. Herein, we present an up-to-date overview on the impact of hormones and factors that modulate SC metabolism, with special focus on glycolytic metabolism, highlighting their relevance in determining male reproductive potential. PMID:26711246

  2. SIZ1-Dependent Post-Translational Modification by SUMO Modulates Sugar Signaling and Metabolism in Arabidopsis thaliana.

    PubMed

    Castro, Pedro Humberto; Verde, Nuno; Lourenço, Tiago; Magalhães, Alexandre Papadopoulos; Tavares, Rui Manuel; Bejarano, Eduardo Rodríguez; Azevedo, Herlânder

    2015-12-01

    Post-translational modification mechanisms function as switches that mediate the balance between optimum growth and the response to environmental stimuli, by regulating the activity of key proteins. SUMO (small ubiquitin-like modifier) attachment, or sumoylation, is a post-translational modification that is essential for the plant stress response, also modulating hormonal circuits to co-ordinate developmental processes. The Arabidopsis SUMO E3 ligase SAP and Miz 1 (SIZ1) is the major SUMO conjugation enhancer in response to stress, and is implicated in several aspects of plant development. Here we report that known SUMO targets are over-represented in multiple carbohydrate-related proteins, suggesting a functional link between sumoylation and sugar metabolism and signaling in plants. We subsequently observed that SUMO-conjugated proteins accumulate in response to high doses of sugar in a SIZ1-dependent manner, and that the null siz1 mutant displays increased expression of sucrose and starch catabolic genes and shows reduced starch levels. We demonstrated that SIZ1 controls germination time and post-germination growth via osmotic and sugar-dependent signaling, respectively. Glucose was specifically linked to SUMO-sugar interplay, with high levels inducing root growth inhibition and aberrant root hair morphology in siz1. The use of sugar analogs and sugar marker gene expression analysis allowed us to implicate SIZ1 in a signaling pathway dependent on glucose metabolism, probably involving modulation of SNF1-related kinase 1 (SnRK1) activity. PMID:26468507

  3. Mixed - Lineage Protein kinases (MLKs) in inflammation, metabolism, and other disease states.

    PubMed

    Craige, Siobhan M; Reif, Michaella M; Kant, Shashi

    2016-09-01

    Mixed lineage kinases, or MLKs, are members of the MAP kinase kinase kinase (MAP3K) family, which were originally identified among the activators of the major stress-dependent mitogen activated protein kinases (MAPKs), JNK and p38. During stress, the activation of JNK and p38 kinases targets several essential downstream substrates that react in a specific manner to the unique stressor and thus determine the fate of the cell in response to a particular challenge. Recently, the MLK family was identified as a specific modulator of JNK and p38 signaling in metabolic syndrome. Moreover, the MLK family of kinases appears to be involved in a very wide spectrum of disorders. This review discusses the newly identified functions of MLKs in multiple diseases including metabolic disorders, inflammation, cancer, and neurological diseases. PMID:27259981

  4. Genetic ablation of carotene oxygenases and consumption of lycopene or tomato powder diets modulates carotenoid and lipid metabolism in mice

    PubMed Central

    Ford, Nikki A.; Elsen, Amy C.; Erdman, John W.

    2013-01-01

    Carotene-15,15'-monooxygenase (CMO-I) cleaves β-carotene to form vitamin A while carotene-9’,10’-monooxygenase (CMO-II) preferentially cleaves non-provitamin A carotenoids. Recent reports indicate that beta-carotene metabolites regulate dietary lipid uptake while lycopene regulates peroxisome-proliferated activator receptor (PPAR) expression. To determine the physiologic consequences of carotenoids and their interactions with CMO-I and CMO-II, we characterized mammalian carotenoid metabolism, metabolic perturbations and lipid metabolism in female CMO-I−/− and CMO-II−/− mice fed lycopene or tomato-containing diets for 30 days. We hypothesized that there would be significant interactions between diet and genotype on carotenoid accumulation and lipid parameters. CMO-I−/− mice had higher levels of leptin, insulin and hepatic lipidosis, but lower levels of serum cholesterol. CMO-II−/− mice had increased tissue lycopene and phytofluene accumulation, reduced IGF-1 levels and cholesterol levels, but elevated liver lipids and cholesterol compared with WT mice. The diets did not modulate these genotypic perturbations, but lycopene and tomato powder did significantly decrease serum insulin-like growth factor-I. Tomato powder also reduced hepatic PPAR expression, independent of genotype. These data point to the pleiotropic actions of CMO-I and CMO-II supporting a strong role of these proteins in regulating tissue carotenoid accumulation and the lipid metabolic phenotype, as well as tomato carotenoid-independent regulation of lipid metabolism. PMID:24034573

  5. Genetic ablation of carotene oxygenases and consumption of lycopene or tomato powder diets modulate carotenoid and lipid metabolism in mice.

    PubMed

    Ford, Nikki A; Elsen, Amy C; Erdman, John W

    2013-09-01

    Carotene-15,15'-monooxygenase (CMO-I) cleaves β-carotene to form vitamin A, whereas carotene-9',10'-monooxygenase (CMO-II) preferentially cleaves non-provitamin A carotenoids. Recent reports indicate that β-carotene metabolites regulate dietary lipid uptake, whereas lycopene regulates peroxisome proliferator-activated receptor expression. To determine the physiologic consequences of carotenoids and their interactions with CMO-I and CMO-II, we characterized mammalian carotenoid metabolism, metabolic perturbations, and lipid metabolism in female CMO-I(-/-) and CMO-II(-/-) mice fed lycopene or tomato-containing diets for 30 days. We hypothesized that there would be significant interactions between diet and genotype on carotenoid accumulation and lipid parameters. CMO-I(-/-) mice had higher levels of leptin, insulin, and hepatic lipidosis but lower levels of serum cholesterol. CMO-II(-/-) mice had increased tissue lycopene and phytofluene accumulation, reduced insulin-like growth factor 1 levels and cholesterol levels, but elevated liver lipids and cholesterol compared with wild-type mice. The diets did not modulate these genotypic perturbations, but lycopene and tomato powder significantly decreased serum insulin-like growth factor 1. Tomato powder also increased hepatic peroxisome proliferator-activated receptor expression, independent of genotype. These data point to the pleiotropic actions of CMO-I and CMO-II supporting a strong role of these proteins in regulating tissue carotenoid accumulation and the lipid metabolic phenotype as well as tomato carotenoid-independent regulation of lipid metabolism. PMID:24034573

  6. Mammalian alpha beta hydrolase domain (ABHD) proteins: lipid metabolizing enzymes at the interface of cell signaling and energy metabolism

    PubMed Central

    Brown, J. Mark

    2016-01-01

    Dysregulation of lipid metabolism underlies many chronic diseases such as obesity, diabetes, cardiovascular disease, and cancer. Therefore, understanding enzymatic mechanisms controlling lipid synthesis and degradation is imperative for successful drug discovery for these human diseases. Genes encoding α/β hydrolase fold domain (ABHD) proteins are present in virtually all reported genomes, and conserved structural motifs shared by these proteins predict common roles in lipid synthesis and degradation. However, the physiological substrates and products for these lipid metabolizing enzymes and their broader role in metabolic pathways remain largely uncharacterized. Recently, mutations in several members of the ABHD protein family have been implicated in inherited inborn errors of lipid metabolism. Furthermore, studies in cell and animal models have revealed important roles for ABHD proteins in lipid metabolism, lipid signal transduction, and metabolic disease. The purpose of this review is to provide a comprehensive summary surrounding the current state of knowledge regarding mammalian ABHD protein family members. In particular, we will discuss how ABHD proteins are ideally suited to act at the interface of lipid metabolism and signal transduction. Although, the current state of knowledge regarding mammalian ABHD proteins is still in its infancy, this review highlights the potential for the ABHD enzymes as being attractive targets for novel therapies targeting metabolic disease. PMID:23328280

  7. Coordinated Metabolic Changes and Modulation of Autophagy during Myogenesis.

    PubMed

    Fortini, Paola; Iorio, Egidio; Dogliotti, Eugenia; Isidoro, Ciro

    2016-01-01

    Autophagy undergoes a fine tuning during tissue differentiation and organ remodeling in order to meet the dynamic changes in the metabolic needs. While the involvement of autophagy in the homeostasis of mature muscle tissues has been intensively studied, no study has so far addressed the regulation of autophagy in relation to the metabolic state during the myogenic differentiation. In our recently published study (Fortini et al., 2016) we investigated the metabolic profile and regulation of autophagy that accompany the differentiation process of mouse skeletal muscle satellite cells (MSC)-derived myoblasts into myotubes. Here, we briefly present these findings also in the light of similar studies conducted by other authors. We show that during myogenic differentiation mitochondrial function and activity are greatly increased, and the activation of autophagy accompanies the transition from myoblasts to myotube. Autophagy is mTORC1 inactivation-independent and, remarkably, is required to allow the myocyte fusion process, as shown by impaired cell fusion when the autophagic flux is inhibited either by genetic or drug manipulation. Further, we found that myoblasts derived from p53 null mice show defective terminal differentiation into myotubes and reduced activation of basal autophagy. Of note, glycolysis prevails and mitochondrial biogenesis is strongly impaired in p53-null myoblasts. Thus, autophagy, mitochondrial homeostasis, and differentiation are finely tuned in a coordinate manner during muscle biogenesis. PMID:27378945

  8. Coordinated Metabolic Changes and Modulation of Autophagy during Myogenesis

    PubMed Central

    Fortini, Paola; Iorio, Egidio; Dogliotti, Eugenia; Isidoro, Ciro

    2016-01-01

    Autophagy undergoes a fine tuning during tissue differentiation and organ remodeling in order to meet the dynamic changes in the metabolic needs. While the involvement of autophagy in the homeostasis of mature muscle tissues has been intensively studied, no study has so far addressed the regulation of autophagy in relation to the metabolic state during the myogenic differentiation. In our recently published study (Fortini et al., 2016) we investigated the metabolic profile and regulation of autophagy that accompany the differentiation process of mouse skeletal muscle satellite cells (MSC)-derived myoblasts into myotubes. Here, we briefly present these findings also in the light of similar studies conducted by other authors. We show that during myogenic differentiation mitochondrial function and activity are greatly increased, and the activation of autophagy accompanies the transition from myoblasts to myotube. Autophagy is mTORC1 inactivation-independent and, remarkably, is required to allow the myocyte fusion process, as shown by impaired cell fusion when the autophagic flux is inhibited either by genetic or drug manipulation. Further, we found that myoblasts derived from p53 null mice show defective terminal differentiation into myotubes and reduced activation of basal autophagy. Of note, glycolysis prevails and mitochondrial biogenesis is strongly impaired in p53-null myoblasts. Thus, autophagy, mitochondrial homeostasis, and differentiation are finely tuned in a coordinate manner during muscle biogenesis. PMID:27378945

  9. Tumor microenvironment derived exosomes pleiotropically modulate cancer cell metabolism

    PubMed Central

    Zhao, Hongyun; Yang, Lifeng; Baddour, Joelle; Achreja, Abhinav; Bernard, Vincent; Moss, Tyler; Marini, Juan C; Tudawe, Thavisha; Seviour, Elena G; San Lucas, F Anthony; Alvarez, Hector; Gupta, Sonal; Maiti, Sourindra N; Cooper, Laurence; Peehl, Donna; Ram, Prahlad T; Maitra, Anirban; Nagrath, Deepak

    2016-01-01

    Cancer-associated fibroblasts (CAFs) are a major cellular component of tumor microenvironment in most solid cancers. Altered cellular metabolism is a hallmark of cancer, and much of the published literature has focused on neoplastic cell-autonomous processes for these adaptations. We demonstrate that exosomes secreted by patient-derived CAFs can strikingly reprogram the metabolic machinery following their uptake by cancer cells. We find that CAF-derived exosomes (CDEs) inhibit mitochondrial oxidative phosphorylation, thereby increasing glycolysis and glutamine-dependent reductive carboxylation in cancer cells. Through 13C-labeled isotope labeling experiments we elucidate that exosomes supply amino acids to nutrient-deprived cancer cells in a mechanism similar to macropinocytosis, albeit without the previously described dependence on oncogenic-Kras signaling. Using intra-exosomal metabolomics, we provide compelling evidence that CDEs contain intact metabolites, including amino acids, lipids, and TCA-cycle intermediates that are avidly utilized by cancer cells for central carbon metabolism and promoting tumor growth under nutrient deprivation or nutrient stressed conditions. DOI: http://dx.doi.org/10.7554/eLife.10250.001 PMID:26920219

  10. A sterol binding protein integrates endosomal lipid metabolism with TOR signaling and nitrogen sensing

    PubMed Central

    Mousley, Carl J.; Yuan, Peihua; Gaur, Naseem A.; Trettin, Kyle D.; Nile, Aaron H.; Deminoff, Stephen J.; Dewar, Brian J.; Wolpert, Max; Macdonald, Jeffrey M.; Herman, Paul K.; Hinnebusch, Alan G.; Bankaitis, Vytas A.

    2012-01-01

    SUMMARY Kes1, and other oxysterol binding protein (OSBP) superfamily members, are involved in membrane and lipid trafficking through trans-Golgi network (TGN) and endosomal systems. We demonstrate that Kes1 represents a sterol-regulated antagonist of TGN/endosomal phosphatidylinositol-4-phosphate signaling. This regulation modulates TOR activation by amino acids, and dampens gene expression driven by Gcn4; the primary transcriptional activator of the general amino acid control regulon. Kes1-mediated repression of Gcn4 transcription factor activity is characterized by nonproductive Gcn4 binding to its target sequences, involves TGN/endosome-derived sphingolipid signaling, and requires activity of the cyclin-dependent kinase 8 (CDK8) module of the enigmatic ‘large Mediator’ complex. These data describe a pathway by which Kes1 integrates lipid metabolism with TORC1 signaling and nitrogen sensing. PMID:22341443

  11. MAPK14/p38α-dependent modulation of glucose metabolism affects ROS levels and autophagy during starvation

    PubMed Central

    Desideri, Enrico; Vegliante, Rolando; Cardaci, Simone; Nepravishta, Ridvan; Paci, Maurizio; Ciriolo, Maria Rosa

    2014-01-01

    Increased glycolytic flux is a common feature of many cancer cells, which have adapted their metabolism to maximize glucose incorporation and catabolism to generate ATP and substrates for biosynthetic reactions. Indeed, glycolysis allows a rapid production of ATP and provides metabolic intermediates required for cancer cells growth. Moreover, it makes cancer cells less sensitive to fluctuations of oxygen tension, a condition usually occurring in a newly established tumor environment. Here, we provide evidence for a dual role of MAPK14 in driving a rearrangement of glucose metabolism that contributes to limiting reactive oxygen species (ROS) production and autophagy activation in condition of nutrient deprivation. We demonstrate that MAPK14 is phosphoactivated during nutrient deprivation and affects glucose metabolism at 2 different levels: on the one hand, it increases SLC2A3 mRNA and protein levels, resulting in a higher incorporation of glucose within the cell. This event involves the MAPK14-mediated enhancement of HIF1A protein stability. On the other hand, MAPK14 mediates a metabolic shift from glycolysis to the pentose phosphate pathway (PPP) through the modulation of PFKFB3 (6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase 3) degradation by the proteasome. This event requires the presence of 2 distinct degradation sequences, KEN box and DSG motif Ser273, which are recognized by 2 different E3 ligase complexes. The mutation of either motif increases PFKFB3 resistance to starvation-induced degradation. The MAPK14-driven metabolic reprogramming sustains the production of NADPH, an important cofactor for many reduction reactions and for the maintenance of the proper intracellular redox environment, resulting in reduced levels of ROS. The final effect is a reduced activation of autophagy and an increased resistance to nutrient deprivation. PMID:25046111

  12. Amino acid metabolism and protein synthesis in malarial parasites*

    PubMed Central

    Sherman, I. W.

    1977-01-01

    Malaria-infected red cells and free parasites have limited capabilities for the biosynthesis of amino acids. Therefore, the principal amino acid sources for parasite protein synthesis are the plasma free amino acids and host cell haemoglobin. Infected cells and plasmodia incorporate exogenously supplied amino acids into protein. However, the hypothesis that amino acid utilization (from an external source) is related to availability of that amino acid in haemoglobin is without universal support: it is true for isoleucine and for Plasmodium knowlesi and P. falciparum, but not for methionine, cysteine, and other amino acids, and it does not apply to P. lophurae. More by default than by direct evidence, haemoglobin is believed to be the main amino acid reservoir available to the intraerythrocytic plasmodium. Haemoglobin, ingested via the cytostome, is held in food vacuoles where auto-oxidation takes place. As a consequence, haem is released and accumulates in the vacuole as particulate haemozoin (= malaria pigment). Current evidence favours the view that haemozoin is mainly haematin. Acid and alkaline proteases (identified in crude extracts from mammalian and avian malarias) are presumably secreted directly into the food vacuole. They then digest the denatured globin and the resulting amino acids are incorporated into parasite protein. Cell-free protein synthesizing systems have been developed using P. knowlesi and P. lophurae ribosomes. In the main these systems are typically eukaryotic. Studies of amino acid metabolism are exceedingly limited. Arginine, lysine, methionine, and proline are incorporated into protein, whereas glutamic acid is metabolized via an NADP-specific glutamic dehydrogenase. Glutamate oxidation generates NADPH and auxiliary energy (in the form of α-ketoglutarate). The role of red cell glutathione in the economy of the parasite remains obscure. Important goals for future research should be: quantitative assessment of the relative importance of

  13. The role of leucine and its metabolites in protein and energy metabolism.

    PubMed

    Duan, Yehui; Li, Fengna; Li, Yinghui; Tang, Yulong; Kong, Xiangfeng; Feng, Zemeng; Anthony, Tracy G; Watford, Malcolm; Hou, Yongqing; Wu, Guoyao; Yin, Yulong

    2016-01-01

    Leucine (Leu) is a nutritionally essential branched-chain amino acid (BCAA) in animal nutrition. It is usually one of the most abundant amino acids in high-quality protein foods. Leu increases protein synthesis through activation of the mammalian target of rapamycin (mTOR) signaling pathway in skeletal muscle, adipose tissue and placental cells. Leu promotes energy metabolism (glucose uptake, mitochondrial biogenesis, and fatty acid oxidation) to provide energy for protein synthesis, while inhibiting protein degradation. Approximately 80 % of Leu is normally used for protein synthesis, while the remainder is converted to α-ketoisocaproate (α-KIC) and β-hydroxy-β-methylbutyrate (HMB) in skeletal muscle. Therefore, it has been hypothesized that some of the functions of Leu are modulated by its metabolites. Both α-KIC and HMB have recently received considerable attention as nutritional supplements used to increase protein synthesis, inhibit protein degradation, and regulate energy homeostasis in a variety of in vitro and in vivo models. Leu and its metabolites hold great promise to enhance the growth and health of animals (including humans, birds and fish). PMID:26255285

  14. Modulation of Alloimmunity by Heat Shock Proteins

    PubMed Central

    Borges, Thiago J.; Lang, Benjamin J.; Lopes, Rafael L.; Bonorino, Cristina

    2016-01-01

    The immunological mechanisms that evolved for host defense against pathogens and injury are also responsible for transplant rejection. Host rejection of foreign tissue was originally thought to be mediated mainly by T cell recognition of foreign MHC alleles. Management of solid organ transplant rejection has thus focused mainly on inhibition of T cell function and matching MHC alleles between donor and host. Recently, however, it has been demonstrated that the magnitude of the initial innate immune responses upon transplantation has a decisive impact on rejection. The exact mechanisms underlying this phenomenon have yet to be characterized. Ischemic cell death and inflammation that occur upon transplantation are synonymous with extracellular release of various heat shock proteins (Hsps), many of which have been shown to have immune-modulatory properties. Here, we review the impact of Hsps upon alloimmunity and discuss the potential use of Hsps as accessory agents to improve solid organ transplant outcomes. PMID:27555846

  15. The gut microbiota modulates host amino acid and glutathione metabolism in mice.

    PubMed

    Mardinoglu, Adil; Shoaie, Saeed; Bergentall, Mattias; Ghaffari, Pouyan; Zhang, Cheng; Larsson, Erik; Bäckhed, Fredrik; Nielsen, Jens

    2015-10-01

    The gut microbiota has been proposed as an environmental factor that promotes the progression of metabolic diseases. Here, we investigated how the gut microbiota modulates the global metabolic differences in duodenum, jejunum, ileum, colon, liver, and two white adipose tissue depots obtained from conventionally raised (CONV-R) and germ-free (GF) mice using gene expression data and tissue-specific genome-scale metabolic models (GEMs). We created a generic mouse metabolic reaction (MMR) GEM, reconstructed 28 tissue-specific GEMs based on proteomics data, and manually curated GEMs for small intestine, colon, liver, and adipose tissues. We used these functional models to determine the global metabolic differences between CONV-R and GF mice. Based on gene expression data, we found that the gut microbiota affects the host amino acid (AA) metabolism, which leads to modifications in glutathione metabolism. To validate our predictions, we measured the level of AAs and N-acetylated AAs in the hepatic portal vein of CONV-R and GF mice. Finally, we simulated the metabolic differences between the small intestine of the CONV-R and GF mice accounting for the content of the diet and relative gene expression differences. Our analyses revealed that the gut microbiota influences host amino acid and glutathione metabolism in mice. PMID:26475342

  16. The gut microbiota modulates host amino acid and glutathione metabolism in mice

    PubMed Central

    Mardinoglu, Adil; Shoaie, Saeed; Bergentall, Mattias; Ghaffari, Pouyan; Zhang, Cheng; Larsson, Erik; Bäckhed, Fredrik; Nielsen, Jens

    2015-01-01

    The gut microbiota has been proposed as an environmental factor that promotes the progression of metabolic diseases. Here, we investigated how the gut microbiota modulates the global metabolic differences in duodenum, jejunum, ileum, colon, liver, and two white adipose tissue depots obtained from conventionally raised (CONV-R) and germ-free (GF) mice using gene expression data and tissue-specific genome-scale metabolic models (GEMs). We created a generic mouse metabolic reaction (MMR) GEM, reconstructed 28 tissue-specific GEMs based on proteomics data, and manually curated GEMs for small intestine, colon, liver, and adipose tissues. We used these functional models to determine the global metabolic differences between CONV-R and GF mice. Based on gene expression data, we found that the gut microbiota affects the host amino acid (AA) metabolism, which leads to modifications in glutathione metabolism. To validate our predictions, we measured the level of AAs and N-acetylated AAs in the hepatic portal vein of CONV-R and GF mice. Finally, we simulated the metabolic differences between the small intestine of the CONV-R and GF mice accounting for the content of the diet and relative gene expression differences. Our analyses revealed that the gut microbiota influences host amino acid and glutathione metabolism in mice. PMID:26475342

  17. Black tea polyphenols modulate xenobiotic-metabolizing enzymes, oxidative stress and adduct formation in a rat hepatocarcinogenesis model.

    PubMed

    Murugan, Ramalingam Senthil; Uchida, Koji; Hara, Yukihiko; Nagini, Siddavaram

    2008-10-01

    The present study was designed to investigate the modulatory effects of black tea polyphenols (Polyphenon-B) on phase I and phase II xenobiotic-metabolizing enzymes and oxidative stress in a rat model of hepatocellular carcinoma (HCC). Liver tumours induced in male Sprague-Dawley rats by dietary administration of rho-dimethylaminoazobenzene (DAB) increased cytochrome P450 (total and CYP1A1, 1A2 and 2B isoforms), cytochrome b(5), cytochrome b(5) reductase, glutathione S-transferase (GST total and GST-P isoform) and gamma-glutamyltranspeptidase (GGT) with decrease in quinone reductase (QR). This was accompanied by enhanced lipid and protein oxidation and compromised antioxidant defences associated with increased expression of the oxidative stress markers 4-hydroxynonenal (4-HNE), anti-hexanoyl lysine (HEL), dibromotyrosine (DiBrY) and 8-hydroxy 2-deoxyguanosine (8-OHdG). Dietary administration of Polyphenon-B effectively suppressed DAB-induced hepatocarcinogenesis, as evidenced by reduced preneoplastic and neoplastic lesions, modulation of xenobiotic-metabolizing enzymes and amelioration of oxidative stress. Thus, it can be concluded that Polyphenon-B acts as an effective chemopreventive agent by modulating xenobiotic-metabolizing enzymes and mitigating oxidative stress in an in vivo model of hepatocarcinogenesis. PMID:18985486

  18. Protein S-glutathionlyation links energy metabolism to redox signaling in mitochondria.

    PubMed

    Mailloux, Ryan J; Treberg, Jason R

    2016-08-01

    At its core mitochondrial function relies on redox reactions. Electrons stripped from nutrients are used to form NADH and NADPH, electron carriers that are similar in structure but support different functions. NADH supports ATP production but also generates reactive oxygen species (ROS), superoxide (O2(·-)) and hydrogen peroxide (H2O2). NADH-driven ROS production is counterbalanced by NADPH which maintains antioxidants in an active state. Mitochondria rely on a redox buffering network composed of reduced glutathione (GSH) and peroxiredoxins (Prx) to quench ROS generated by nutrient metabolism. As H2O2 is quenched, NADPH is expended to reactivate antioxidant networks and reset the redox environment. Thus, the mitochondrial redox environment is in a constant state of flux reflecting changes in nutrient and ROS metabolism. Changes in redox environment can modulate protein function through oxidation of protein cysteine thiols. Typically cysteine oxidation is considered to be mediated by H2O2 which oxidizes protein thiols (SH) forming sulfenic acid (SOH). However, problems begin to emerge when one critically evaluates the regulatory function of SOH. Indeed SOH formation is slow, non-specific, and once formed SOH reacts rapidly with a variety of molecules. By contrast, protein S-glutathionylation (PGlu) reactions involve the conjugation and removal of glutathione moieties from modifiable cysteine residues. PGlu reactions are driven by fluctuations in the availability of GSH and oxidized glutathione (GSSG) and thus should be exquisitely sensitive to changes ROS flux due to shifts in the glutathione pool in response to varying H2O2 availability. Here, we propose that energy metabolism-linked redox signals originating from mitochondria are mediated indirectly by H2O2 through the GSH redox buffering network in and outside mitochondria. This proposal is based on several observations that have shown that unlike other redox modifications PGlu reactions fulfill the requisite

  19. Protein S-glutathionlyation links energy metabolism to redox signaling in mitochondria

    PubMed Central

    Mailloux, Ryan J.; Treberg, Jason R.

    2015-01-01

    At its core mitochondrial function relies on redox reactions. Electrons stripped from nutrients are used to form NADH and NADPH, electron carriers that are similar in structure but support different functions. NADH supports ATP production but also generates reactive oxygen species (ROS), superoxide (O2·-) and hydrogen peroxide (H2O2). NADH-driven ROS production is counterbalanced by NADPH which maintains antioxidants in an active state. Mitochondria rely on a redox buffering network composed of reduced glutathione (GSH) and peroxiredoxins (Prx) to quench ROS generated by nutrient metabolism. As H2O2 is quenched, NADPH is expended to reactivate antioxidant networks and reset the redox environment. Thus, the mitochondrial redox environment is in a constant state of flux reflecting changes in nutrient and ROS metabolism. Changes in redox environment can modulate protein function through oxidation of protein cysteine thiols. Typically cysteine oxidation is considered to be mediated by H2O2 which oxidizes protein thiols (SH) forming sulfenic acid (SOH). However, problems begin to emerge when one critically evaluates the regulatory function of SOH. Indeed SOH formation is slow, non-specific, and once formed SOH reacts rapidly with a variety of molecules. By contrast, protein S-glutathionylation (PGlu) reactions involve the conjugation and removal of glutathione moieties from modifiable cysteine residues. PGlu reactions are driven by fluctuations in the availability of GSH and oxidized glutathione (GSSG) and thus should be exquisitely sensitive to changes ROS flux due to shifts in the glutathione pool in response to varying H2O2 availability. Here, we propose that energy metabolism-linked redox signals originating from mitochondria are mediated indirectly by H2O2 through the GSH redox buffering network in and outside mitochondria. This proposal is based on several observations that have shown that unlike other redox modifications PGlu reactions fulfill the requisite

  20. Modulation of fructokinase activity of potato (Solanum tuberosum) results in substantial shifts in tuber metabolism.

    PubMed

    Davies, Howard V; Shepherd, Louise V T; Burrell, Michael M; Carrari, Fernando; Urbanczyk-Wochniak, Ewa; Leisse, Andrea; Hancock, Robert D; Taylor, Mark; Viola, Roberto; Ross, Heather; McRae, Diane; Willmitzer, Lothar; Fernie, Alisdair R

    2005-07-01

    Potato plants (Solanum tuberosum L. cvs Desiree and Record) transformed with sense and antisense constructs of a cDNA encoding the potato fructokinase StFK1 exhibited altered transcription of this gene, altered amount of protein and altered enzyme activities. Measurement of the maximal catalytic activity of fructokinase revealed a 2-fold variation in leaf (from 90 to 180% of wild type activity) and either a 10- or 30-fold variation in tuber (from 10 or 30% to 300% in Record and Desiree, respectively) activity. The comparative effect of the antisense construct in leaf and tuber tissue suggests that this isoform is only a minor contributor to the total fructokinase activity in the leaf but the predominant isoform in the tuber. Antisense inhibition of the fructokinase resulted in a reduced tuber yield; however, its overexpression had no impact on this parameter. The modulation of fructokinase activity had few, consistent effects on carbohydrate levels, with the exception of a general increase in glucose content in the antisense lines, suggesting that this enzyme is not important for the control of starch synthesis. However, when metabolic fluxes were estimated, it became apparent that the transgenic lines display a marked shift in metabolism, with the rate of redistribution of radiolabel to sucrose markedly affected by the activity of fructokinase. These data suggest an important role for fructokinase, acting in concert with sucrose synthase, in maintaining a balance between sucrose synthesis and degradation by a mechanism independent of that controlled by the hexose phosphate-mediated activation of sucrose phosphate synthase. PMID:15890680

  1. The metabolic modulator trimetazidine triggers autophagy and counteracts stress-induced atrophy in skeletal muscle myotubes.

    PubMed

    Ferraro, Elisabetta; Giammarioli, Anna Maria; Caldarola, Sara; Lista, Pasquale; Feraco, Alessandra; Tinari, Antonella; Salvatore, Anna Maria; Malorni, Walter; Berghella, Libera; Rosano, Giuseppe

    2013-10-01

    It has recently been demonstrated that trimetazidine (TMZ), an anti-ischemic antianginal agent, is also able to improve exercise performance in patients with peripheral arterial disease. TMZ is a metabolic modulator, and the mechanisms underlying its cytoprotective anti-ischemic activity could be ascribed, at least in cardiomyocytes, to optimization of metabolism. However, regarding the cytoprotection exerted by TMZ on skeletal muscle and allowing the improvement of exercise performance, no information is yet available. In the present study, we investigated in detail the protective effects of this drug on in vitro skeletal muscle models of atrophy. Experiments carried out with murine C2C12 myotubes treated with TMZ revealed that this drug could efficiently counteract the cytopathic effects induced by the proinflammatory cytokine tumor necrosis factor-α and by the withdrawal of growth factors. Indeed, TMZ significantly counteracted the reduction in myotube size induced by these treatments. TMZ also increased myosin heavy chain expression and induced hypertrophy in C2C12 myotubes, both effects strongly suggesting a role of TMZ in counteracting atrophy in vitro. In particular, we found that TMZ was able to activate the phosphoinositide 3-kinase-Akt-mammalian target of rapamycin 2 pathway and to reduce the stress-induced transcriptional upregulation of atrogin-1, muscle ring finger protein 1, and myostatin, all of which are key molecules involved in muscle wasting. Moreover, this is the first demonstration that TMZ induces autophagy, a key mechanism involved in muscle mass regulation. On the basis of these results, it can be hypothesized that the improvement in exercise performance previously observed in patients could be ascribed to a cytoprotective mechanism exerted by TMZ on skeletal muscle integrity. PMID:23953053

  2. Whole body protein metabolism in children with cancer.

    PubMed Central

    Daley, S E; Pearson, A D; Craft, A W; Kernahan, J; Wyllie, R A; Price, L; Brock, C; Hetherington, C; Halliday, D; Bartlett, K

    1996-01-01

    Whole body protein synthesis and catabolism were measured using the [ring-2H5]phenylalanine and [1-13C]leucine primed constant infusion technique in 32 paediatric patients with cancer at different stages of treatment. Rates of synthesis (S) and catabolism (C) derived from the [ring-2H5]phenylalanine and [1-13C]leucine models were 4.7 (SD 1.3) (S) and 6.0 (1.5) (C) g/d/kg, and 5.5 (0.8) (S) and 6.8 (1.2) (C) g/d/kg, respectively. These results show that these two tracer techniques give similar results in this study population. Comparison of these values with results previously reported for groups of control children using the [ring-2H5]phenylalanine model (S = 3.69 and 3.93; C = 4.09 and 4.28 g/d/kg) and the [1-13C]leucine model (S = 4.32; C = 4.85 g/d/kg) show that rates of synthesis and catabolism were higher in cancer patients than in controls. Thus whole body protein turnover is increased in children under treatment for cancer. Other indices of metabolism such as plasma amino acids and intermediary metabolites were also measured and showed that, although subjects were in isotopic steady state, there were significant metabolic changes during the course of the primed constant infusions used to measure protein turnover. PMID:8984910

  3. Arabidopsis ribosomal proteins control vacuole trafficking and developmental programs through the regulation of lipid metabolism

    PubMed Central

    Li, Ruixi; Sun, Ruobai; Hicks, Glenn R.; Raikhel, Natasha V.

    2015-01-01

    The vacuole is the most prominent compartment in plant cells and is important for ion and protein storage. In our effort to search for key regulators in the plant vacuole sorting pathway, ribosomal large subunit 4 (rpl4d) was identified as a translational mutant defective in both vacuole trafficking and normal development. Polysome profiling of the rpl4d mutant showed reduction in polysome-bound mRNA compared with wild-type, but no significant change in the general mRNA distribution pattern. Ribsomal profiling data indicated that genes in the lipid metabolism pathways were translationally down-regulated in the rpl4d mutant. Live imaging studies by Nile red staining suggested that both polar and nonpolar lipid accumulation was reduced in meristem tissues of rpl4d mutants. Pharmacological evidence showed that sterol and sphingolipid biosynthetic inhibitors can phenocopy the defects of the rpl4d mutant, including an altered vacuole trafficking pattern. Genetic evidence from lipid biosynthetic mutants indicates that alteration in the metabolism of either sterol or sphingolipid biosynthesis resulted in vacuole trafficking defects, similar to the rpl4d mutant. Tissue-specific complementation with key enzymes from lipid biosynthesis pathways can partially rescue both vacuole trafficking and auxin-related developmental defects in the rpl4d mutant. These results indicate that lipid metabolism modulates auxin-mediated tissue differentiation and endomembrane trafficking pathways downstream of ribosomal protein function. PMID:25535344

  4. Lipid metabolizing enzyme activities modulated by phospholipid substrate lateral distribution.

    PubMed

    Salinas, Dino G; Reyes, Juan G; De la Fuente, Milton

    2011-09-01

    Biological membranes contain many domains enriched in phospholipid lipids and there is not yet clear explanation about how these domains can control the activity of phospholipid metabolizing enzymes. Here we used the surface dilution kinetic theory to derive general equations describing how complex substrate distributions affect the activity of enzymes following either the phospholipid binding kinetic model (which assumes that the enzyme molecules directly bind the phospholipid substrate molecules), or the surface-binding kinetic model (which assumes that the enzyme molecules bind to the membrane before binding the phospholipid substrate). Our results strongly suggest that, if the enzyme follows the phospholipid binding kinetic model, any substrate redistribution would increase the enzyme activity over than observed for a homogeneous distribution of substrate. Besides, enzymes following the surface-binding model would be independent of the substrate distribution. Given that the distribution of substrate in a population of micelles (each of them a lipid domain) should follow a Poisson law, we demonstrate that the general equations give an excellent fit to experimental data of lipases acting on micelles, providing reasonable values for kinetic parameters--without invoking special effects such as cooperative phenomena. Our theory will allow a better understanding of the cellular-metabolism control in membranes, as well as a more simple analysis of the mechanisms of membrane acting enzymes. PMID:21108012

  5. Modulation of apoptosis by V protein mumps virus

    PubMed Central

    2011-01-01

    Background The Urabe AM9 vaccine strain of mumps virus contains two variants of V protein: VWT (of HN-A1081 viral population) and VGly (of HN-G1081). The V protein is a promoting factor of viral replication by blocking the IFN antiviral pathway. Findings We studied the relationship between V protein variants and IFN-α2b-induced apoptosis. V proteins decrease activation of the extrinsic IFN-α2b-induced apoptotic pathway monitored by the caspase 8 activity, being the effect greater with the VWT protein. Both V proteins decrease the activity of caspase 9 of the intrinsic apoptotic pathway. In a system without IFN, the VWT and VGly proteins expression promotes activation of caspases 3 and 7. However, when the cellular system was stimulated with IFN-α, this activity decreased partially. TUNEL assay shows that for treatment with IFN-α and ibuprofen of cervical adenocarcinoma cells there is nuclear DNA fragmentation but the V protein expression reduces this process. Conclusions The reduction in the levels of caspases and DNA fragmentation, suggesting that V protein, particularly VWT protein of Urabe AM9 vaccine strain, modulates apoptosis. In addition, the VWT protein shows a protective role for cell proliferation in the presence of antiproliferative signals. PMID:21569530

  6. Leucine and Protein Metabolism in Obese Zucker Rats

    PubMed Central

    She, Pengxiang; Olson, Kristine C.; Kadota, Yoshihiro; Inukai, Ayami; Shimomura, Yoshiharu; Hoppel, Charles L.; Adams, Sean H.; Kawamata, Yasuko; Matsumoto, Hideki; Sakai, Ryosei; Lang, Charles H.; Lynch, Christopher J.

    2013-01-01

    Branched-chain amino acids (BCAAs) are circulating nutrient signals for protein accretion, however, they increase in obesity and elevations appear to be prognostic of diabetes. To understand the mechanisms whereby obesity affects BCAAs and protein metabolism, we employed metabolomics and measured rates of [1-14C]-leucine metabolism, tissue-specific protein synthesis and branched-chain keto-acid (BCKA) dehydrogenase complex (BCKDC) activities. Male obese Zucker rats (11-weeks old) had increased body weight (BW, 53%), liver (107%) and fat (∼300%), but lower plantaris and gastrocnemius masses (−21–24%). Plasma BCAAs and BCKAs were elevated 45–69% and ∼100%, respectively, in obese rats. Processes facilitating these rises appeared to include increased dietary intake (23%), leucine (Leu) turnover and proteolysis [35% per g fat free mass (FFM), urinary markers of proteolysis: 3-methylhistidine (183%) and 4-hydroxyproline (766%)] and decreased BCKDC per g kidney, heart, gastrocnemius and liver (−47–66%). A process disposing of circulating BCAAs, protein synthesis, was increased 23–29% by obesity in whole-body (FFM corrected), gastrocnemius and liver. Despite the observed decreases in BCKDC activities per gm tissue, rates of whole-body Leu oxidation in obese rats were 22% and 59% higher normalized to BW and FFM, respectively. Consistently, urinary concentrations of eight BCAA catabolism-derived acylcarnitines were also elevated. The unexpected increase in BCAA oxidation may be due to a substrate effect in liver. Supporting this idea, BCKAs were elevated more in liver (193–418%) than plasma or muscle, and per g losses of hepatic BCKDC activities were completely offset by increased liver mass, in contrast to other tissues. In summary, our results indicate that plasma BCKAs may represent a more sensitive metabolic signature for obesity than BCAAs. Processes supporting elevated BCAA]BCKAs in the obese Zucker rat include increased dietary intake, Leu and

  7. Concerted modulation of alanine and glutamate metabolism in young Medicago truncatula seedlings under hypoxic stress

    PubMed Central

    Limami, Anis M.; Glévarec, Gaëlle; Ricoult, Claudie; Cliquet, Jean-Bernard; Planchet, Elisabeth

    2008-01-01

    The modulation of primary nitrogen metabolism by hypoxic stress was studied in young Medicago truncatula seedlings. Hypoxic seedlings were characterized by the up-regulation of glutamate dehydrogenase 1 (GDH1) and mitochondrial alanine aminotransferase (mAlaAT), and down-regulation of glutamine synthetase 1b (GS1b), NADH-glutamate synthase (NADH-GOGAT), glutamate dehydrogenase 3 (GDH3), and isocitrate dehydrogenase (ICDH) gene expression. Hypoxic stress severely inhibited GS activity and stimulated NADH-GOGAT activity. GDH activity was lower in hypoxic seedlings than in the control, however, under either normoxia or hypoxia, the in vivo activity was directed towards glutamate deamination. 15NH4 labelling showed for the first time that the adaptive reaction of the plant to hypoxia consisted of a concerted modulation of nitrogen flux through the pathways of both alanine and glutamate synthesis. In hypoxic seedlings, newly synthesized 15N-alanine increased and accumulated as the major amino acid, asparagine synthesis was inhibited, while 15N-glutamate was synthesized at a similar rate to that in the control. A discrepancy between the up-regulation of GDH1 expression and the down-regulation of GDH activity by hypoxic stress highlighted for the first time the complex regulation of this enzyme by hypoxia. Higher rates of glycolysis and ethanol fermentation are known to cause the fast depletion of sugar stores and carbon stress. It is proposed that the expression of GDH1 was stimulated by hypoxia-induced carbon stress, while the enzyme protein might be involved during post-hypoxic stress contributing to the regeneration of 2-oxoglutarate via the GDH shunt. PMID:18508812

  8. Ruminant Nutrition Symposium: Modulation of metabolism through nutrition and management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The primary role of the dairy cow is to help provide high-quality protein and other nutrients through lactation to the human diet. It is clear that these high-producing and long lactations are stressful on the cows, and minor changes in nutrition and management can have significant impacts on profi...

  9. Metabolic Flux Ratio Analysis of Genetic and Environmental Modulations of Escherichia coli Central Carbon Metabolism

    PubMed Central

    Sauer, Uwe; Lasko, Daniel R.; Fiaux, Jocelyne; Hochuli, Michel; Glaser, Ralf; Szyperski, Thomas; Wüthrich, Kurt; Bailey, James E.

    1999-01-01

    The response of Escherichia coli central carbon metabolism to genetic and environmental manipulation has been studied by use of a recently developed methodology for metabolic flux ratio (METAFoR) analysis; this methodology can also directly reveal active metabolic pathways. Generation of fluxome data arrays by use of the METAFoR approach is based on two-dimensional 13C-1H correlation nuclear magnetic resonance spectroscopy with fractionally labeled biomass and, in contrast to metabolic flux analysis, does not require measurements of extracellular substrate and metabolite concentrations. METAFoR analyses of E. coli strains that moderately overexpress phosphofructokinase, pyruvate kinase, pyruvate decarboxylase, or alcohol dehydrogenase revealed that only a few flux ratios change in concert with the overexpression of these enzymes. Disruption of both pyruvate kinase isoenzymes resulted in altered flux ratios for reactions connecting the phosphoenolpyruvate (PEP) and pyruvate pools but did not significantly alter central metabolism. These data indicate remarkable robustness and rigidity in central carbon metabolism in the presence of genetic variation. More significant physiological changes and flux ratio differences were seen in response to altered environmental conditions. For example, in ammonia-limited chemostat cultures, compared to glucose-limited chemostat cultures, a reduced fraction of PEP molecules was derived through at least one transketolase reaction, and there was a higher relative contribution of anaplerotic PEP carboxylation than of the tricarboxylic acid (TCA) cycle for oxaloacetate synthesis. These two parameters also showed significant variation between aerobic and anaerobic batch cultures. Finally, two reactions catalyzed by PEP carboxykinase and malic enzyme were identified by METAFoR analysis; these had previously been considered absent in E. coli cells grown in glucose-containing media. Backward flux from the TCA cycle to glycolysis, as

  10. Protein complexes and functional modules in molecular networks

    NASA Astrophysics Data System (ADS)

    Spirin, Victor; Mirny, Leonid A.

    2003-10-01

    Proteins, nucleic acids, and small molecules form a dense network of molecular interactions in a cell. Molecules are nodes of this network, and the interactions between them are edges. The architecture of molecular networks can reveal important principles of cellular organization and function, similarly to the way that protein structure tells us about the function and organization of a protein. Computational analysis of molecular networks has been primarily concerned with node degree [Wagner, A. & Fell, D. A. (2001) Proc. R. Soc. London Ser. B 268, 1803-1810; Jeong, H., Tombor, B., Albert, R., Oltvai, Z. N. & Barabasi, A. L. (2000) Nature 407, 651-654] or degree correlation [Maslov, S. & Sneppen, K. (2002) Science 296, 910-913], and hence focused on single/two-body properties of these networks. Here, by analyzing the multibody structure of the network of protein-protein interactions, we discovered molecular modules that are densely connected within themselves but sparsely connected with the rest of the network. Comparison with experimental data and functional annotation of genes showed two types of modules: (i) protein complexes (splicing machinery, transcription factors, etc.) and (ii) dynamic functional units (signaling cascades, cell-cycle regulation, etc.). Discovered modules are highly statistically significant, as is evident from comparison with random graphs, and are robust to noise in the data. Our results provide strong support for the network modularity principle introduced by Hartwell et al. [Hartwell, L. H., Hopfield, J. J., Leibler, S. & Murray, A. W. (1999) Nature 402, C47-C52], suggesting that found modules constitute the "building blocks" of molecular networks.

  11. The modulation of leaf metabolism plays a role in salt tolerance of Cymodocea nodosa exposed to hypersaline stress in mesocosms

    PubMed Central

    Piro, Amalia; Marín-Guirao, Lázaro; Serra, Ilia A.; Spadafora, Antonia; Sandoval-Gil, José M.; Bernardeau-Esteller, Jaime; Fernandez, Juan M. R.; Mazzuca, Silvia

    2015-01-01

    Applying proteomics, we tested the physiological responses of the euryhaline seagrass Cymodocea nodosa to deliberate manipulation of salinity in a mesocosm system. Plants were subjected to a chronic hypersaline condition (43 psu) to compare protein expression and plant photochemistry responses after 15 and 30 days of exposure with those of plants cultured under normal/ambient saline conditions (37 psu). Results showed a general decline in the expression level of leaf proteins in hypersaline stressed plants, with more intense reductions after long-lasting exposure. Specifically, the carbon-fixing enzyme RuBisCo displayed a lower accumulation level in stressed plants relative to controls. In contrast, the key enzymes involved in the regulation of glycolysis, cytosolic glyceraldehyde-3-phosphate dehydrogenase, enolase 2 and triose-phosphate isomerase, showed significantly higher accumulation levels. These responses suggested a shift in carbon metabolism in stressed plants. Hypersaline stress also induced a significant alteration of the photosynthetic physiology of C. nodosa by means of a down-regulation in structural proteins and enzymes of both PSII and PSI. However we found an over-expression of the cytochrome b559 alpha subunit of the PSII initial complex, which is a receptor for the PSII core proteins involved in biogenesis or repair processes and therefore potentially involved in the absence of effects at the photochemical level of stressed plants. As expected hypersalinity also affects vacuolar metabolism by increasing the leaf cell turgor pressure and enhancing the up-take of Na+ by over-accumulating the tonoplast specific intrinsic protein pyrophosphate-energized inorganic pyrophosphatase (H(+)-PPase) coupled to the Na+/H+-antiporter. The modulation of carbon metabolism and the enhancement of vacuole capacity in Na+ sequestration and osmolarity changes are discussed in relation to salt tolerance of C. nodosa. PMID:26167167

  12. Multidomain Carbohydrate-binding Proteins Involved in Bacteroides thetaiotaomicron Starch Metabolism*

    PubMed Central

    Cameron, Elizabeth A.; Maynard, Mallory A.; Smith, Christopher J.; Smith, Thomas J.; Koropatkin, Nicole M.; Martens, Eric C.

    2012-01-01

    Human colonic bacteria are necessary for the digestion of many dietary polysaccharides. The intestinal symbiont Bacteroides thetaiotaomicron uses five outer membrane proteins to bind and degrade starch. Here, we report the x-ray crystallographic structures of SusE and SusF, two outer membrane proteins composed of tandem starch specific carbohydrate-binding modules (CBMs) with no enzymatic activity. Examination of the two CBMs in SusE and three CBMs in SusF reveals subtle differences in the way each binds starch and is reflected in their Kd values for both high molecular weight starch and small maltooligosaccharides. Thus, each site seems to have a unique starch preference that may enable these proteins to interact with different regions of starch or its breakdown products. Proteins similar to SusE and SusF are encoded in many other polysaccharide utilization loci that are possessed by human gut bacteria in the phylum Bacteroidetes. Thus, these proteins are likely to play an important role in carbohydrate metabolism in these abundant symbiotic species. Understanding structural changes that diversify and adapt related proteins in the human gut microbial community will be critical to understanding the detailed mechanistic roles that they perform in the complex digestive ecosystem. PMID:22910908

  13. Transcriptional Profiles of Drought-Related Genes in Modulating Metabolic Processes and Antioxidant Defenses in Lolium multiflorum

    PubMed Central

    Pan, Ling; Zhang, Xinquan; Wang, Jianping; Ma, Xiao; Zhou, Meiliang; Huang, LinKai; Nie, Gang; Wang, Pengxi; Yang, Zhongfu; Li, Ji

    2016-01-01

    Drought is a major environmental stress that limits growth and development of cool-season annual grasses. Drought transcriptional profiles of resistant and susceptible lines were studied to understand the molecular mechanisms of drought tolerance in annual ryegrass (Lolium multiflorum L.). A total of 4718 genes exhibited significantly differential expression in two L. multiflorum lines. Additionally, up-regulated genes associated with drought response in the resistant lines were compared with susceptible lines. Gene ontology enrichment and pathway analyses revealed that genes partially encoding drought-responsive proteins as key regulators were significantly involved in carbon metabolism, lipid metabolism, and signal transduction. Comparable gene expression was used to identify the genes that contribute to the high drought tolerance in resistant lines of annual ryegrass. Moreover, we proposed the hypothesis that short-term drought have a beneficial effect on oxidation stress, which may be ascribed to a direct effect on the drought tolerance of annual ryegrass. Evidence suggests that some of the genes encoding antioxidants (HPTs, GGT, AP, 6-PGD, and G6PDH) function as antioxidant in lipid metabolism and signal transduction pathways, which have indispensable and promoting roles in drought resistance. This study provides the first transcriptome data on the induction of drought-related gene expression in annual ryegrass, especially via modulation of metabolic homeostasis, signal transduction, and antioxidant defenses to improve drought tolerance response to short-term drought stress. PMID:27200005

  14. Physiological and Pathogenic Roles of Prolyl Isomerase Pin1 in Metabolic Regulations via Multiple Signal Transduction Pathway Modulations.

    PubMed

    Nakatsu, Yusuke; Matsunaga, Yasuka; Yamamotoya, Takeshi; Ueda, Koji; Inoue, Yuki; Mori, Keiichi; Sakoda, Hideyuki; Fujishiro, Midori; Ono, Hiraku; Kushiyama, Akifumi; Asano, Tomoichiro

    2016-01-01

    Prolyl isomerases are divided into three groups, the FKBP family, Cyclophilin and the Parvulin family (Pin1 and Par14). Among these isomerases, Pin1 is a unique prolyl isomerase binding to the motif including pSer/pThr-Pro that is phosphorylated by kinases. Once bound, Pin1 modulates the enzymatic activity, protein stability or subcellular localization of target proteins by changing the cis- and trans-formations of proline. Several studies have examined the roles of Pin1 in the pathogenesis of cancers and Alzheimer's disease. On the other hand, recent studies have newly demonstrated Pin1 to be involved in regulating glucose and lipid metabolism. Interestingly, while Pin1 expression is markedly increased by high-fat diet feeding, Pin1 KO mice are resistant to diet-induced obesity, non-alcoholic steatohepatitis and diabetic vascular dysfunction. These phenomena result from the binding of Pin1 to several key factors regulating metabolic functions, which include insulin receptor substrate-1, AMPK, Crtc2 and NF-κB p65. In this review, we focus on recent advances in elucidating the physiological roles of Pin1 as well as the pathogenesis of disorders involving this isomerase, from the viewpoint of the relationships between signal transductions and metabolic functions. PMID:27618008

  15. Text mining for metabolic pathways, signaling cascades, and protein networks.

    PubMed

    Hoffmann, Robert; Krallinger, Martin; Andres, Eduardo; Tamames, Javier; Blaschke, Christian; Valencia, Alfonso

    2005-05-10

    The complexity of the information stored in databases and publications on metabolic and signaling pathways, the high throughput of experimental data, and the growing number of publications make it imperative to provide systems to help the researcher navigate through these interrelated information resources. Text-mining methods have started to play a key role in the creation and maintenance of links between the information stored in biological databases and its original sources in the literature. These links will be extremely useful for database updating and curation, especially if a number of technical problems can be solved satisfactorily, including the identification of protein and gene names (entities in general) and the characterization of their types of interactions. The first generation of openly accessible text-mining systems, such as iHOP (Information Hyperlinked over Proteins), provides additional functions to facilitate the reconstruction of protein interaction networks, combine database and text information, and support the scientist in the formulation of novel hypotheses. The next challenge is the generation of comprehensive information regarding the general function of signaling pathways and protein interaction networks. PMID:15886388

  16. Changes in contralateral protein metabolism following unilateral sciatic nerve section

    SciTech Connect

    Menendez, J.A.; Cubas, S.C.

    1990-03-01

    Changes in nerve biochemistry, anatomy, and function following injuries to the contralateral nerve have been repeatedly reported, though their significance is unknown. The most likely mechanisms for their development are either substances carried by axoplasmic flow or electrically transmitted signals. This study analyzes which mechanism underlies the development of a contralateral change in protein metabolism. The incorporation of labelled amino acids (AA) into proteins of both sciatic nerves was assessed by liquid scintillation after an unilateral section. AA were offered locally for 30 min to the distal stump of the sectioned nerves and at homologous levels of the intact contralateral nerves. At various times, from 1 to 24 h, both sciatic nerves were removed and the proteins extracted with trichloroacetic acid (TCA). An increase in incorporation was found in both nerves 14-24 h after section. No difference existed between sectioned and intact nerves, which is consistent with the contralateral effect. Lidocaine, but not colchicine, when applied previously to the nerves midway between the sectioning site and the spinal cord, inhibited the contralateral increase in AA incorporation. It is concluded that electrical signals, crossing through the spinal cord, are responsible for the development of the contralateral effect. Both the nature of the proteins and the significance of the contralateral effect are matters for speculation.

  17. Acute responses of muscle protein metabolism to reduced blood flow reflect metabolic priorities for homeostasis.

    PubMed

    Zhang, Xiao-Jun; Irtun, Oivind; Chinkes, David L; Wolfe, Robert R

    2008-03-01

    The present experiment was designed to measure the synthetic and breakdown rates of muscle protein in the hindlimb of rabbits with or without clamping the femoral artery. l-[ring-(13)C(6)]phenylalanine was infused as a tracer for measurement of muscle protein kinetics by means of an arteriovenous model, tracer incorporation, and tracee release methods. The ultrasonic flowmeter, dye dilution, and microsphere methods were used to determine the flow rates in the femoral artery, in the leg, and in muscle capillary, respectively. The femoral artery flow accounted for 65% of leg flow. A 50% reduction in the femoral artery flow reduced leg flow by 28% and nutritive flow by 26%, which did not change protein synthetic or breakdown rate in leg muscle. Full clamp of the femoral artery reduced leg flow by 42% and nutritive flow by 59%, which decreased (P < 0.05) both the fractional synthetic rate from 0.19 +/- 0.05 to 0.14 +/- 0.03%/day and fractional breakdown rate from 0.28 +/- 0.07 to 0.23 +/- 0.09%/day of muscle protein. Neither the partial nor full clamp reduced (P = 0.27-0.39) the intracellular phenylalanine concentration or net protein balance in leg muscle. We conclude that the flow threshold to cause a fall of protein turnover rate in leg muscle was a reduction of 30-40% of the leg flow. The acute responses of muscle protein kinetics to the reductions in blood flow reflected the metabolic priorities to maintain muscle homeostasis. These findings cannot be extrapolated to more chronic conditions without experimental validation. PMID:18089763

  18. Photonic cancer therapy: modulating cellular metabolism with light

    NASA Astrophysics Data System (ADS)

    Coutinho, Isabel; Correia, Manuel; Viruthachalam, Thiagarajan; Gajula, Gnana Prakash; Petersen, Steffen B.; Neves-Petersen, Maria Teresa

    2013-03-01

    The epidermal growth factor receptor (EGFR) belongs to the ErbB family of receptor tyrosine kinases. EGFR activation upon binding of ligands (such as EGF and TGF-α) results in cell signaling cascades that promote cell proliferation, survival and apoptosis inhibition. As reported for many solid tumors, EGFR overactivation is associated with tumor development and progression, resistance to cancer therapies and poor prognosis. Therefore, inhibition of EGFR function is a rational cancer therapy approach. We have shown previously that 280 nm UV illumination of two cancer cell lines overexpressing EGFR could prevent phosphorylation of EGFR and of its downstream signalling molecules despite the presence of EGF. Our earlier studies demonstrated that UV illumination of aromatic residues in proteins leads to the disruption of nearby disulphide bridges. Since human EGFR is rich in disulphide bridges and aromatic residues, it is likely that structural changes can be induced upon UV excitation of its pool of aromatic residues (Trp, Tyr and Phe). Such changes may impair the correct binding of ligands to EGFR which will halt the process of tumor growth. In this paper we report structural changes induced by UV light on the extracellular domain of human EGFR. Steady state fluorescence spectroscopy and binding immunoassays were carried out. Our goal is to gain insight at the protein structure level that explains the way the new photonic cancer therapy works. This technology can be applicable to the treatment of various forms of cancer, alone or in combination with other therapies to improve treatment outcome.

  19. Salacia oblonga root improves cardiac lipid metabolism in Zucker diabetic fatty rats: Modulation of cardiac PPAR-{alpha}-mediated transcription of fatty acid metabolic genes

    SciTech Connect

    Huang, Tom H.-W.; Yang Qinglin; Harada, Masaki; Uberai, Jasna; Radford, Jane; Li, George Q.; Yamahara, Johji; Roufogalis, Basil D.; Li Yuhao . E-mail: yuhao@pharm.usyd.edu.au

    2006-01-15

    Excess cardiac triglyceride accumulation in diabetes and obesity induces lipotoxicity, which predisposes the myocytes to death. On the other hand, increased cardiac fatty acid (FA) oxidation plays a role in the development of myocardial dysfunction in diabetes. PPAR-{alpha} plays an important role in maintaining homeostasis of lipid metabolism. We have previously demonstrated that the extract from Salacia oblonga root (SOE), an Ayurvedic anti-diabetic and anti-obesity medicine, improves hyperlipidemia in Zucker diabetic fatty (ZDF) rats (a genetic model of type 2 diabetes and obesity) and possesses PPAR-{alpha} activating properties. Here we demonstrate that chronic oral administration of SOE reduces cardiac triglyceride and FA contents and decreases the Oil red O-stained area in the myocardium of ZDF rats, which parallels the effects on plasma triglyceride and FA levels. Furthermore, the treatment suppressed cardiac overexpression of both FA transporter protein-1 mRNA and protein in ZDF rats, suggesting inhibition of increased cardiac FA uptake as the basis for decreased cardiac FA levels. Additionally, the treatment also inhibited overexpression in ZDF rat heart of PPAR-{alpha} mRNA and protein and carnitine palmitoyltransferase-1, acyl-CoA oxidase and 5'-AMP-activated protein kinase mRNAs and restored the downregulated acetyl-CoA carboxylase mRNA. These results suggest that SOE inhibits cardiac FA oxidation in ZDF rats. Thus, our findings suggest that improvement by SOE of excess cardiac lipid accumulation and increased cardiac FA oxidation in diabetes and obesity occurs by reduction of cardiac FA uptake, thereby modulating cardiac PPAR-{alpha}-mediated FA metabolic gene transcription.

  20. Polyamine acetylation modulates polyamine metabolic flux, a prelude to broader metabolic consequences.

    PubMed

    Kramer, Debora L; Diegelman, Paula; Jell, Jason; Vujcic, Slavoljub; Merali, Salim; Porter, Carl W

    2008-02-15

    Recent studies suggest that overexpression of the polyamine-acetylating enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) significantly increases metabolic flux through the polyamine pathway. The concept derives from the observation that SSAT-induced acetylation of polyamines gives rise to a compensatory increase in biosynthesis and presumably to increased flow through the pathway. Despite the strength of this deduction, the existence of heightened polyamine flux has not yet been experimentally demonstrated. Here, we use the artificial polyamine precursor 4-fluoro-ornithine to measure polyamine flux by tracking fluorine unit permeation of polyamine pools in human prostate carcinoma LNCaP cells. Conditional overexpression of SSAT was accompanied by a massive increase in intracellular and extracellular acetylated spermidine and by a 6-20-fold increase in biosynthetic enzyme activities. In the presence of 300 microM 4-fluoro-ornithine, SSAT overexpression led to the sequential appearance of fluorinated putrescine, spermidine, acetylated spermidine, and spermine. As fluorinated polyamines increased, endogenous polyamines decreased, so that the total polyamine pool size remained relatively constant. At 24 h, 56% of the spermine pool in the induced SSAT cells was fluorine-labeled compared with only 12% in uninduced cells. Thus, SSAT induction increased metabolic flux by approximately 5-fold. Flux could be interrupted by inhibition of polyamine biosynthesis but not by inhibition of polyamine oxidation. Overall, the findings are consistent with a paradigm whereby flux is initiated by SSAT acetylation of spermine and particularly spermidine followed by a marked increase in key biosynthetic enzymes. The latter sustains the flux cycle by providing a constant supply of polyamines for subsequent acetylation by SSAT. The broader metabolic implications of this futile metabolic cycling are discussed in detail. PMID:18089555

  1. Light quality modulates metabolic synchronization over the diel phases of crassulacean acid metabolism.

    PubMed

    Ceusters, Johan; Borland, Anne M; Taybi, Tahar; Frans, Mario; Godts, Christof; De Proft, Maurice P

    2014-07-01

    Temporal compartmentation of carboxylation processes is a defining feature of crassulacean acid metabolism and involves circadian control of key metabolic and transport steps that regulate the supply and demand for carbon over a 24h cycle. Recent insights on the molecular workings of the circadian clock and its connection with environmental inputs raise new questions on the importance of light quality and, by analogy, certain photoreceptors for synchronizing the metabolic components of CAM. The present work tested the hypothesis that optimal coupling of stomatal conductance, net CO2 uptake, and the reciprocal turnover of carbohydrates and organic acids over the diel CAM cycle requires both blue and red light input signals. Contrasting monochromatic wavelengths of blue, green, and red light (i.e. 475, 530, 630nm) with low fluence rates (10 μmol m(-2) s(-1)) were administered for 16 hours each diel cycle for a total treatment time of 48 hours to the obligate CAM bromeliad, Aechmea 'Maya'. Of the light treatments imposed, low-fluence blue light was a key determinant in regulating stomatal responses, organic acid mobilization from the vacuole, and daytime decarboxylation. However, the reciprocal relationship between starch and organic acid turnover that is typical for CAM was uncoupled under low-fluence blue light. Under low-fluence red or green light, the diel turnover of storage carbohydrates was orchestrated in line with the requirements of CAM, but a consistent delay in acid consumption at dawn compared with plants under white or low-fluence blue light was noted. Consistent with the acknowledged influences of both red and blue light as input signals for the circadian clock, the data stress the importance of both red and blue-light signalling pathways for synchronizing the metabolic and physiological components of CAM over the day/night cycle. PMID:24803500

  2. Light quality modulates metabolic synchronization over the diel phases of crassulacean acid metabolism

    PubMed Central

    Ceusters, Johan; Borland, Anne M.; Taybi, Tahar; Frans, Mario; Godts, Christof; De Proft, Maurice P.

    2014-01-01

    Temporal compartmentation of carboxylation processes is a defining feature of crassulacean acid metabolism and involves circadian control of key metabolic and transport steps that regulate the supply and demand for carbon over a 24h cycle. Recent insights on the molecular workings of the circadian clock and its connection with environmental inputs raise new questions on the importance of light quality and, by analogy, certain photoreceptors for synchronizing the metabolic components of CAM. The present work tested the hypothesis that optimal coupling of stomatal conductance, net CO2 uptake, and the reciprocal turnover of carbohydrates and organic acids over the diel CAM cycle requires both blue and red light input signals. Contrasting monochromatic wavelengths of blue, green, and red light (i.e. 475, 530, 630nm) with low fluence rates (10 μmol m–2 s–1) were administered for 16 hours each diel cycle for a total treatment time of 48 hours to the obligate CAM bromeliad, Aechmea ‘Maya’. Of the light treatments imposed, low-fluence blue light was a key determinant in regulating stomatal responses, organic acid mobilization from the vacuole, and daytime decarboxylation. However, the reciprocal relationship between starch and organic acid turnover that is typical for CAM was uncoupled under low-fluence blue light. Under low-fluence red or green light, the diel turnover of storage carbohydrates was orchestrated in line with the requirements of CAM, but a consistent delay in acid consumption at dawn compared with plants under white or low-fluence blue light was noted. Consistent with the acknowledged influences of both red and blue light as input signals for the circadian clock, the data stress the importance of both red and blue-light signalling pathways for synchronizing the metabolic and physiological components of CAM over the day/night cycle. PMID:24803500

  3. Alternative modulation of protein–protein interactions by small molecules

    PubMed Central

    Fischer, Gerhard; Rossmann, Maxim; Hyvönen, Marko

    2015-01-01

    Protein–protein interactions (PPI) have become increasingly popular drug targets, with a number of promising compounds currently in clinical trials. Recent research shows, that PPIs can be modulated in more ways than direct inhibition, where novel non-competitive modes of action promise a solution for the difficult nature of PPI drug discovery. Here, we review recently discovered PPI modulators in light of their mode of action and categorise them as disrupting versus stabilising, orthosteric versus allosteric and by their ability to affect the proteins’ dynamics. We also give recent examples of compounds successful in the clinic, analyse their physicochemical properties and discuss how to overcome the hurdles in discovering alternative modes of modulation. PMID:25935873

  4. Ecology Drives the Distribution of Specialized Tyrosine Metabolism Modules in Fungi

    PubMed Central

    Greene, George H.; McGary, Kriston L.; Rokas, Antonis; Slot, Jason C.

    2014-01-01

    Gene clusters encoding accessory or environmentally specialized metabolic pathways likely play a significant role in the evolution of fungal genomes. Two such gene clusters encoding enzymes associated with the tyrosine metabolism pathway (KEGG #00350) have been identified in the filamentous fungus Aspergillus fumigatus. The l-tyrosine degradation (TD) gene cluster encodes a functional module that facilitates breakdown of the phenolic amino acid, l-tyrosine through a homogentisate intermediate, but is also involved in the production of pyomelanin, a fungal pathogenicity factor. The gentisate catabolism (GC) gene cluster encodes a functional module likely involved in phenolic compound degradation, which may enable metabolism of biphenolic stilbenes in multiple lineages. Our investigation of the evolution of the TD and GC gene clusters in 214 fungal genomes revealed spotty distributions partially shaped by gene cluster loss and horizontal gene transfer (HGT). Specifically, a TD gene cluster shows evidence of HGT between the extremophilic, melanized fungi Exophiala dermatitidis and Baudoinia compniacensis, and a GC gene cluster shows evidence of HGT between Sordariomycete and Dothideomycete grass pathogens. These results suggest that the distribution of specialized tyrosine metabolism modules is influenced by both the ecology and phylogeny of fungal species. PMID:24391152

  5. Modulators of Hepatic Lipoprotein Metabolism Identified in a Search for Small-Molecule Inducers of Tribbles Pseudokinase 1 Expression

    PubMed Central

    Nagiec, Marek M.; Skepner, Adam P.; Negri, Joseph; Eichhorn, Michelle; Kuperwasser, Nicolas; Comer, Eamon; Muncipinto, Giovanni; Subramanian, Aravind; Clish, Clary; Musunuru, Kiran; Duvall, Jeremy R.; Foley, Michael; Perez, Jose R.; Palmer, Michelle A. J.

    2015-01-01

    Recent genome wide association studies have linked tribbles pseudokinase 1 (TRIB1) to the risk of coronary artery disease (CAD). Based on the observations that increased expression of TRIB1 reduces secretion of VLDL and is associated with lower plasma levels of LDL cholesterol and triglycerides, higher plasma levels of HDL cholesterol and reduced risk for myocardial infarction, we carried out a high throughput phenotypic screen based on quantitative RT-PCR assay to identify compounds that induce TRIB1 expression in human HepG2 hepatoma cells. In a screen of a collection of diversity-oriented synthesis (DOS)-derived compounds, we identified a series of benzofuran-based compounds that upregulate TRIB1 expression and phenocopy the effects of TRIB1 cDNA overexpression, as they inhibit triglyceride synthesis and apoB secretion in cells. In addition, the compounds downregulate expression of MTTP and APOC3, key components of the lipoprotein assembly pathway. However, CRISPR-Cas9 induced chromosomal disruption of the TRIB1 locus in HepG2 cells, while confirming its regulatory role in lipoprotein metabolism, demonstrated that the effects of benzofurans persist in TRIB1-null cells indicating that TRIB1 is sufficient but not necessary to transmit the effects of the drug. Remarkably, active benzofurans, as well as natural products capable of TRIB1 upregulation, also modulate hepatic cell cholesterol metabolism by elevating the expression of LDLR transcript and LDL receptor protein, while reducing the levels of PCSK9 transcript and secreted PCSK9 protein and stimulating LDL uptake. The effects of benzofurans are not masked by cholesterol depletion and are independent of the SREBP-2 regulatory circuit, indicating that these compounds represent a novel class of chemically tractable small-molecule modulators that shift cellular lipoprotein metabolism in HepG2 cells from lipogenesis to scavenging. PMID:25811180

  6. The variable C-terminus of cysteine string proteins modulates exocytosis and protein-protein interactions.

    PubMed

    Boal, Frédéric; Zhang, Hui; Tessier, Céline; Scotti, Pier; Lang, Jochen

    2004-12-28

    Cysteine string proteins (Csps) are vesicle proteins involved in neurotransmission and hormone exocytosis. They are composed of distinct domains: a variable N-terminus, a J-domain followed by a linker region, a cysteine-rich string, and a C-terminus which diverges among isoforms. Their precise function and interactions are not fully understood. Using insulin exocytosis as a model, we show that the linker region and the C-terminus, but not the variable N-terminus, regulate overall secretion. Moreover, endogenous Csp1 binds in a calcium-dependent manner to monomeric VAMP2, and this interaction requires the C-terminus of Csp. The interaction is isoform specific as recombinant Csp1 binds VAMP1 and VAMP7, but not VAMP3. Cross-linking in permeabilized clonal beta-cells revealed homodimerization of Csp which is stimulated by Ca(2+) and again modulated by the variant C-terminus. Our data suggest that both interactions of Csp occur during exocytosis and may explain the effect of the variant C-terminus of this chaperon protein on peptide hormone secretion. PMID:15610015

  7. Molecular tweezers modulate 14-3-3 protein-protein interactions.

    PubMed

    Bier, David; Rose, Rolf; Bravo-Rodriguez, Kenny; Bartel, Maria; Ramirez-Anguita, Juan Manuel; Dutt, Som; Wilch, Constanze; Klärner, Frank-Gerrit; Sanchez-Garcia, Elsa; Schrader, Thomas; Ottmann, Christian

    2013-03-01

    Supramolecular chemistry has recently emerged as a promising way to modulate protein functions, but devising molecules that will interact with a protein in the desired manner is difficult as many competing interactions exist in a biological environment (with solvents, salts or different sites for the target biomolecule). We now show that lysine-specific molecular tweezers bind to a 14-3-3 adapter protein and modulate its interaction with partner proteins. The tweezers inhibit binding between the 14-3-3 protein and two partner proteins--a phosphorylated (C-Raf) protein and an unphosphorylated one (ExoS)--in a concentration-dependent manner. Protein crystallography shows that this effect arises from the binding of the tweezers to a single surface-exposed lysine (Lys214) of the 14-3-3 protein in the proximity of its central channel, which normally binds the partner proteins. A combination of structural analysis and computer simulations provides rules for the tweezers' binding preferences, thus allowing us to predict their influence on this type of protein-protein interactions. PMID:23422566

  8. Non-Genomic Origins of Proteins and Metabolism

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew

    2003-01-01

    It is proposed that evolution of inanimate matter to cells endowed with a nucleic acid- based coding of genetic information was preceded by an evolutionary phase, in which peptides not coded by nucleic acids were able to self-organize into networks capable of evolution towards increasing metabolic complexity. Recent findings that truly different, simple peptides (Keefe and Szostak, 2001) can perform the same function (such as ATP binding) provide experimental support for this mechanism of early protobiological evolution. The central concept underlying this mechanism is that the reproduction of cellular functions alone was sufficient for self-maintenance of protocells, and that self- replication of macromolecules was not required at this stage of evolution. The precise transfer of information between successive generations of the earliest protocells was unnecessary and, possibly, undesirable. The key requirement in the initial stage of protocellular evolution was an ability to rapidly explore a large number of protein sequences in order to discover a set of molecules capable of supporting self- maintenance and growth of protocells. Undoubtedly, the essential protocellular functions were carried out by molecules not nearly as efficient or as specific as contemporary proteins. Many, potentially unrelated sequences could have performed each of these functions at an evolutionarily acceptable level. As evolution progressed, however proteins must have performed their functions with increasing efficiency and specificity. This, in turn, put additional constraints on protein sequences and the fraction of proteins capable of performing their functions at the required level decreased. At some point, the likelihood of generating a sufficiently efficient set of proteins through a non-coded synthesis was so small that further evolution was not possible without storing information about the sequences of these proteins. Beyond this point, further evolution required coupling between

  9. The Bladder Tumor Suppressor Protein TERE1 (UBIAD1)Modulates Cell Cholesterol: Implications for Tumor Progression

    PubMed Central

    McGarvey, Terry; Wang, Huiyi; Lal, Priti; Puthiyaveettil, Raghunath; Tomaszewski, John; Sepulveda, Jorge; Labelle, Ed; Weiss, Jayne S.; Nickerson, Michael L.; Kruth, Howard S.; Brandt, Wolfgang; Wessjohann, Ludger A.; Malkowicz, S. Bruce

    2011-01-01

    Convergent evidence implicates the TERE1 protein in human bladder tumor progression and lipid metabolism. Previously, reduced TERE1 expression was found in invasive urologic cancers and inhibited cell growth upon re-expression. A role in lipid metabolism was suggested by TERE1 binding to APOE, a cholesterol carrier, and to TBL2, a candidate protein in triglyceride disorders. Natural TERE1 mutations associate with Schnyder's corneal dystrophy, characterized by lipid accumulation. TERE1 catalyzes menaquinone synthesis, known to affect cholesterol homeostasis. To explore this relationship, we altered TERE1 and TBL2 dosage via ectopic expression and interfering RNA and measured cholesterol by Amplex red. Protein interactions of wild-type and mutant TERE1 with GST-APOE were evaluated by binding assays and molecular modeling. We conducted a bladder tumor microarray TERE1 expression analysis and assayed tumorigenicity of J82 cells ectopically expressing TERE1. TERE1 expression was reduced in a third of invasive specimens. Ectopic TERE1 expression in J82 bladder cancer cells dramatically inhibited nude mouse tumorigenesis. TERE1 and TBL2 proteins inversely modulated cellular cholesterol in HEK293 and bladder cancer cells from 20% to 50%. TERE1 point mutations affected APOE interactions, and resulted in cholesterol levels that differed from wild type. Elevated tumor cell cholesterol is known to affect apoptosis and growth signaling; thus, loss of TERE1 in invasive bladder cancer may represent a defect in menaquinone-mediated cholesterol homeostasis that contributes to progression. PMID:21740188

  10. Modulation of Rab GTPase function by a protein phosphocholine transferase.

    PubMed

    Mukherjee, Shaeri; Liu, Xiaoyun; Arasaki, Kohei; McDonough, Justin; Galán, Jorge E; Roy, Craig R

    2011-09-01

    The intracellular pathogen Legionella pneumophila modulates the activity of host GTPases to direct the transport and assembly of the membrane-bound compartment in which it resides. In vitro studies have indicated that the Legionella protein DrrA post-translationally modifies the GTPase Rab1 by a process called AMPylation. Here we used mass spectrometry to investigate post-translational modifications to Rab1 that occur during infection of host cells by Legionella. Consistent with in vitro studies, DrrA-mediated AMPylation of a conserved tyrosine residue in the switch II region of Rab1 was detected during infection. In addition, a modification to an adjacent serine residue in Rab1 was discovered, which was independent of DrrA. The Legionella effector protein AnkX was required for this modification. Biochemical studies determined that AnkX directly mediates the covalent attachment of a phosphocholine moiety to Rab1. This phosphocholine transferase activity used CDP-choline as a substrate and required a conserved histidine residue located in the FIC domain of the AnkX protein. During infection, AnkX modified both Rab1 and Rab35, which explains how this protein modulates membrane transport through both the endocytic and exocytic pathways of the host cell. Thus, phosphocholination of Rab GTPases represents a mechanism by which bacterial FIC-domain-containing proteins can alter host-cell functions. PMID:21822290

  11. Red wine polyphenols modulate fecal microbiota and reduce markers of the metabolic syndrome in obese patients.

    PubMed

    Moreno-Indias, Isabel; Sánchez-Alcoholado, Lidia; Pérez-Martínez, Pablo; Andrés-Lacueva, Cristina; Cardona, Fernando; Tinahones, Francisco; Queipo-Ortuño, María Isabel

    2016-04-01

    This study evaluated the possible prebiotic effect of a moderate intake of red wine polyphenols on the modulation of the gut microbiota composition and the improvement in the risk factors for the metabolic syndrome in obese patients. Ten metabolic syndrome patients and ten healthy subjects were included in a randomized, crossover, controlled intervention study. After a washout period, the subjects consumed red wine and de-alcoholized red wine over a 30 day period for each. The dominant bacterial composition did not differ significantly between the study groups after the two red wine intake periods. In the metabolic syndrome patients, red wine polyphenols significantly increased the number of fecal bifidobacteria and Lactobacillus (intestinal barrier protectors) and butyrate-producing bacteria (Faecalibacterium prausnitzii and Roseburia) at the expense of less desirable groups of bacteria such as LPS producers (Escherichia coli and Enterobacter cloacae). The changes in gut microbiota in these patients could be responsible for the improvement in the metabolic syndrome markers. Modulation of the gut microbiota by using red wine could be an effective strategy for managing metabolic diseases associated with obesity. PMID:26599039

  12. Experimental study on trace chemical contaminant generation rates of human metabolism in spacecraft crew module

    NASA Astrophysics Data System (ADS)

    Lihua, Guo; Xinxing, He; Guoxin, Xu; Xin, Qi

    2012-12-01

    Trace chemical contaminants generated by human metabolism is a major source of contamination in spacecraft crew module. In this research, types and generation rates of pollutants from human metabolism were determined in the Chinese diets. Expired air, skin gas, and sweat of 20 subjects were analyzed at different exercise states in a simulated module. The exercise states were designed according to the basic activities in the orbit of astronauts. Qualitative and quantitative analyses of contaminants generated by human metabolic were performed with gas chromatography/mass spectrometry, gas chromatography and UV spectrophotometer. Sixteen chemical compounds from metabolic sources were found. With the increase in physical load, the concentrations of chemical compounds from human skin and expired air correspondingly increased. The species and the offgassing rates of pollutants from human metabolism are different among the Chinese, Americans and the Russians due to differences in ethnicity and dietary customs. This research provides data to aid in the design, development and operation of China's long duration space mission.

  13. Unwinding activity of cold shock proteins and RNA metabolism.

    PubMed

    Phadtare, Sangita

    2011-01-01

    Temperature downshift from 37 °C to 15 °C results in the exertion of cold shock response in Escherichia coli, which induces cold shock proteins, such as CsdA. Previously, we showed that the helicase activity of CsdA is critical for its function in the cold acclimation of cells and its primary role is mRNA degradation. Only RhlE (helicase), CspA (RNA chaperone) and RNase R (exoribonuclease) were found to complement the cold shock function of CsdA. RNase R has two independent activities, helicase and ribonuclease, only helicase being essential for the functional complementation of CsdA. Here, we discuss the significance of above findings as these emphasize the importance of the unwinding activity of cold-shock-inducible proteins in the RNA metabolism at low temperature, which may be different than that at 37 °C. It requires assistance of proteins to destabilize the secondary structures in mRNAs that are stabilized upon temperature downshift, hindering the activity of ribonucleases. PMID:21445001

  14. Molecular tweezers modulate 14-3-3 protein-protein interactions

    NASA Astrophysics Data System (ADS)

    Bier, David; Rose, Rolf; Bravo-Rodriguez, Kenny; Bartel, Maria; Ramirez-Anguita, Juan Manuel; Dutt, Som; Wilch, Constanze; Klärner, Frank-Gerrit; Sanchez-Garcia, Elsa; Schrader, Thomas; Ottmann, Christian

    2013-03-01

    Supramolecular chemistry has recently emerged as a promising way to modulate protein functions, but devising molecules that will interact with a protein in the desired manner is difficult as many competing interactions exist in a biological environment (with solvents, salts or different sites for the target biomolecule). We now show that lysine-specific molecular tweezers bind to a 14-3-3 adapter protein and modulate its interaction with partner proteins. The tweezers inhibit binding between the 14-3-3 protein and two partner proteins—a phosphorylated (C-Raf) protein and an unphosphorylated one (ExoS)—in a concentration-dependent manner. Protein crystallography shows that this effect arises from the binding of the tweezers to a single surface-exposed lysine (Lys214) of the 14-3-3 protein in the proximity of its central channel, which normally binds the partner proteins. A combination of structural analysis and computer simulations provides rules for the tweezers' binding preferences, thus allowing us to predict their influence on this type of protein-protein interactions.

  15. Modulation of arachidonic acid metabolism by Rous sarcoma virus

    SciTech Connect

    Barker, K.; Aderem, A.; Hanafusa, H. )

    1989-07-01

    Arachidonic acid (C{sub 20:4}) metabolites were released constitutively from wild-type Rous sarcoma virus-transformed chicken embryo fibroblasts (CEF). {sup 3}H-labeled C{sub 20:4} and its metabolites were released from unstimulated and uninfected CEF only in response to stimuli such as serum, phorbol ester, or the calcium ionophore A23187. High-pressure liquid chromatography analysis showed that the radioactivity released from ({sup 3}H)arachidonate-labeled transformed cells was contained in free arachidonate and in the cyclooxygenase products prostaglandin E{sub 2} and prostaglandin F{sub 2} alpha; no lipoxygenase products were identified. The release of C{sub 20:4} and its metabolites from CEF infected with pp60{sup src} deletion mutants was correlated with serum-independent DNA synthesis and with the expression of the mRNA for 9E3, a gene expressed in Rous sarcoma virus-transformed cells which has homology with several mitogenic and inflammatory peptides. {sup 3}H-labeled C{sub 20:4} release was not correlated with p36 phosphorylation, which argues against a role for this protein as a phospholipase A{sub 2} inhibitor. CEF infected with other oncogenic viruses encoding a tyrosine kinase also released C{sub 20:4}, as did CEF infected with viruses that contained mos and ras; however, infection with a crk-containing virus did not result in stimulation of {sup 3}H-labeled C{sub 20:4} release, suggesting that utilization of this signaling pathway is specific for particular transformation stimuli.

  16. Exosome engineering for efficient intracellular delivery of soluble proteins using optically reversible protein-protein interaction module.

    PubMed

    Yim, Nambin; Ryu, Seung-Wook; Choi, Kyungsun; Lee, Kwang Ryeol; Lee, Seunghee; Choi, Hojun; Kim, Jeongjin; Shaker, Mohammed R; Sun, Woong; Park, Ji-Ho; Kim, Daesoo; Heo, Won Do; Choi, Chulhee

    2016-01-01

    Nanoparticle-mediated delivery of functional macromolecules is a promising method for treating a variety of human diseases. Among nanoparticles, cell-derived exosomes have recently been highlighted as a new therapeutic strategy for the in vivo delivery of nucleotides and chemical drugs. Here we describe a new tool for intracellular delivery of target proteins, named 'exosomes for protein loading via optically reversible protein-protein interactions' (EXPLORs). By integrating a reversible protein-protein interaction module controlled by blue light with the endogenous process of exosome biogenesis, we are able to successfully load cargo proteins into newly generated exosomes. Treatment with protein-loaded EXPLORs is shown to significantly increase intracellular levels of cargo proteins and their function in recipient cells in vitro and in vivo. These results clearly indicate the potential of EXPLORs as a mechanism for the efficient intracellular transfer of protein-based therapeutics into recipient cells and tissues. PMID:27447450

  17. Protein dynamics modulated electron transfer kinetics in early stage photosynthesis

    NASA Astrophysics Data System (ADS)

    Kundu, Prasanta; Dua, Arti

    2013-01-01

    A recent experiment has probed the electron transfer kinetics in the early stage of photosynthesis in Rhodobacter sphaeroides for the reaction center of wild type and different mutants [Science 316, 747 (2007)]. By monitoring the changes in the transient absorption of the donor-acceptor pair at 280 and 930 nm, both of which show non-exponential temporal decay, the experiment has provided a strong evidence that the initial electron transfer kinetics is modulated by the dynamics of protein backbone. In this work, we present a model where the electron transfer kinetics of the donor-acceptor pair is described along the reaction coordinate associated with the distance fluctuations in a protein backbone. The stochastic evolution of the reaction coordinate is described in terms of a non-Markovian generalized Langevin equation with a memory kernel and Gaussian colored noise, both of which are completely described in terms of the microscopics of the protein normal modes. This model provides excellent fits to the transient absorption signals at 280 and 930 nm associated with protein distance fluctuations and protein dynamics modulated electron transfer reaction, respectively. In contrast to previous models, the present work explains the microscopic origins of the non-exponential decay of the transient absorption curve at 280 nm in terms of multiple time scales of relaxation of the protein normal modes. Dynamic disorder in the reaction pathway due to protein conformational fluctuations which occur on time scales slower than or comparable to the electron transfer kinetics explains the microscopic origin of the non-exponential nature of the transient absorption decay at 930 nm. The theoretical estimates for the relative driving force for five different mutants are in close agreement with the experimental estimates obtained using electrochemical measurements.

  18. Protein dynamics modulated electron transfer kinetics in early stage photosynthesis.

    PubMed

    Kundu, Prasanta; Dua, Arti

    2013-01-28

    A recent experiment has probed the electron transfer kinetics in the early stage of photosynthesis in Rhodobacter sphaeroides for the reaction center of wild type and different mutants [Science 316, 747 (2007)]. By monitoring the changes in the transient absorption of the donor-acceptor pair at 280 and 930 nm, both of which show non-exponential temporal decay, the experiment has provided a strong evidence that the initial electron transfer kinetics is modulated by the dynamics of protein backbone. In this work, we present a model where the electron transfer kinetics of the donor-acceptor pair is described along the reaction coordinate associated with the distance fluctuations in a protein backbone. The stochastic evolution of the reaction coordinate is described in terms of a non-Markovian generalized Langevin equation with a memory kernel and Gaussian colored noise, both of which are completely described in terms of the microscopics of the protein normal modes. This model provides excellent fits to the transient absorption signals at 280 and 930 nm associated with protein distance fluctuations and protein dynamics modulated electron transfer reaction, respectively. In contrast to previous models, the present work explains the microscopic origins of the non-exponential decay of the transient absorption curve at 280 nm in terms of multiple time scales of relaxation of the protein normal modes. Dynamic disorder in the reaction pathway due to protein conformational fluctuations which occur on time scales slower than or comparable to the electron transfer kinetics explains the microscopic origin of the non-exponential nature of the transient absorption decay at 930 nm. The theoretical estimates for the relative driving force for five different mutants are in close agreement with the experimental estimates obtained using electrochemical measurements. PMID:23387626

  19. Contact sensitizers modulate the arachidonic acid metabolism of PMA-differentiated U-937 monocytic cells activated by LPS.

    PubMed

    Del Bufalo, Aurélia; Bernad, José; Dardenne, Christophe; Verda, Denis; Meunier, Jean Roch; Rousset, Françoise; Martinozzi-Teissier, Silvia; Pipy, Bernard

    2011-10-01

    For the effective induction of a hapten-specific T cell immune response toward contact sensitizers, in addition to covalent-modification of skin proteins, the redox and inflammatory statuses of activated dendritic cells are crucial. The aim of this study was to better understand how sensitizers modulate an inflammatory response through cytokines production and COX metabolism cascade. To address this purpose, we used the human monocytic-like U-937 cell line differentiated by phorbol myristate acetate (PMA) and investigated the effect of 6 contact sensitizers (DNCB, PPD, hydroquinone, propyl gallate, cinnamaldehyde and eugenol) and 3 non sensitizers (lactic acid, glycerol and tween 20) on the production of pro-inflammatory cytokines (IL-1β and TNF-α) and on the arachidonic acid metabolic profile after bacterial lipopolysaccharide (LPS) stimulation. Our results showed that among the tested molecules, all sensitizers specifically prevent the production of PMA/LPS-induced COX-2 metabolites (PGE(2,) TxB(2) and PGD(2)), eugenol and cinnamaldehyde inhibiting also the production of IL-1β and TNF-α. We further demonstrated that there is no unique PGE(2) inhibition mechanism: while the release of arachidonic acid (AA) from membrane phospholipids does not appear do be a target of modulation, COX-2 expression and/or COX-2 enzymatic activity are the major steps of prostaglandin synthesis that are inhibited by sensitizers. Altogether these results add a new insight into the multiple biochemical effects described for sensitizers. PMID:21807015

  20. Role of forkhead box protein A3 in age-associated metabolic decline

    PubMed Central

    Ma, Xinran; Xu, Lingyan; Gavrilova, Oksana; Mueller, Elisabetta

    2014-01-01

    Aging is associated with increased adiposity and diminished thermogenesis, but the critical transcription factors influencing these metabolic changes late in life are poorly understood. We recently demonstrated that the winged helix factor forkhead box protein A3 (Foxa3) regulates the expansion of visceral adipose tissue in high-fat diet regimens; however, whether Foxa3 also contributes to the increase in adiposity and the decrease in brown fat activity observed during the normal aging process is currently unknown. Here we report that during aging, levels of Foxa3 are significantly and selectively up-regulated in brown and inguinal white fat depots, and that midage Foxa3-null mice have increased white fat browning and thermogenic capacity, decreased adipose tissue expansion, improved insulin sensitivity, and increased longevity. Foxa3 gain-of-function and loss-of-function studies in inguinal adipose depots demonstrated a cell-autonomous function for Foxa3 in white fat tissue browning. Furthermore, our analysis revealed that the mechanisms of Foxa3 modulation of brown fat gene programs involve the suppression of peroxisome proliferator activated receptor γ coactivtor 1 α (PGC1α) levels through interference with cAMP responsive element binding protein 1-mediated transcriptional regulation of the PGC1α promoter. Overall, our data demonstrate a role for Foxa3 in energy expenditure and in age-associated metabolic disorders. PMID:25225406

  1. Deciphering the biological effects of acupuncture treatment modulating multiple metabolism pathways

    PubMed Central

    Zhang, Aihua; Yan, Guangli; Sun, Hui; Cheng, Weiping; Meng, Xiangcai; Liu, Li; Xie, Ning; Wang, Xijun

    2016-01-01

    Acupuncture is an alternative therapy that is widely used to treat various diseases. However, detailed biological interpretation of the acupuncture stimulations is limited. We here used metabolomics and proteomics technology, thereby identifying the serum small molecular metabolites into the effect and mechanism pathways of standardized acupuncture treatments at ‘Zusanli’ acupoint which was the most often used acupoint in previous reports. Comprehensive overview of serum metabolic profiles during acupuncture stimulation was investigated. Thirty-four differential metabolites were identified in serum metabolome and associated with ten metabolism pathways. Importantly, we have found that high impact glycerophospholipid metabolism, fatty acid metabolism, ether lipid metabolism were acutely perturbed by acupuncture stimulation. As such, these alterations may be useful to clarify the biological mechanism of acupuncture stimulation. A series of differentially expressed proteins were identified and such effects of acupuncture stimulation were found to play a role in transport, enzymatic activity, signaling pathway or receptor interaction. Pathway analysis further revealed that most of these proteins were found to play a pivotal role in the regulation of multiple metabolism pathways. It demonstrated that the metabolomics coupled with proteomics as a powerful approach for potential applications in understanding the biological effects of acupuncture stimulation. PMID:26879284

  2. Modulator of Apoptosis 1 (MOAP-1) Is a Tumor Suppressor Protein Linked to the RASSF1A Protein*

    PubMed Central

    Law, Jennifer; Salla, Mohamed; Zare, Alaa; Wong, Yoke; Luong, Le; Volodko, Natalia; Svystun, Orysya; Flood, Kayla; Lim, Jonathan; Sung, Miranda; Dyck, Jason R. B.; Tan, Chong Teik; Su, Yu-Chin; Yu, Victor C.; Mackey, John; Baksh, Shairaz

    2015-01-01

    Modulator of apoptosis 1 (MOAP-1) is a BH3-like protein that plays key roles in cell death or apoptosis. It is an integral partner to the tumor suppressor protein, Ras association domain family 1A (RASSF1A), and functions to activate the Bcl-2 family pro-apoptotic protein Bax. Although RASSF1A is now considered a bona fide tumor suppressor protein, the role of MOAP-1 as a tumor suppressor protein has yet to be determined. In this study, we present several lines of evidence from cancer databases, immunoblotting of cancer cells, proliferation, and xenograft assays as well as DNA microarray analysis to demonstrate the role of MOAP-1 as a tumor suppressor protein. Frequent loss of MOAP-1 expression, in at least some cancers, appears to be attributed to mRNA down-regulation and the rapid proteasomal degradation of MOAP-1 that could be reversed utilizing the proteasome inhibitor MG132. Overexpression of MOAP-1 in several cancer cell lines resulted in reduced tumorigenesis and up-regulation of genes involved in cancer regulatory pathways that include apoptosis (p53, Fas, and MST1), DNA damage control (poly(ADP)-ribose polymerase and ataxia telangiectasia mutated), those within the cell metabolism (IR-α, IR-β, and AMP-activated protein kinase), and a stabilizing effect on microtubules. The loss of RASSF1A (an upstream regulator of MOAP-1) is one of the earliest detectable epigenetically silenced tumor suppressor proteins in cancer, and we speculate that the additional loss of function of MOAP-1 may be a second hit to functionally compromise the RASSF1A/MOAP-1 death receptor-dependent pathway and drive tumorigenesis. PMID:26269600

  3. Integrated pathway modules using time-course metabolic profiles and EST data from Milnesium tardigradum

    PubMed Central

    2012-01-01

    Background Tardigrades are multicellular organisms, resistant to extreme environmental changes such as heat, drought, radiation and freezing. They outlast these conditions in an inactive form (tun) to escape damage to cellular structures and cell death. Tardigrades are apparently able to prevent or repair such damage and are therefore a crucial model organism for stress tolerance. Cultures of the tardigrade Milnesium tardigradum were dehydrated by removing the surrounding water to induce tun formation. During this process and the subsequent rehydration, metabolites were measured in a time series by GC-MS. Additionally expressed sequence tags are available, especially libraries generated from the active and inactive state. The aim of this integrated analysis is to trace changes in tardigrade metabolism and identify pathways responsible for their extreme resistance against physical stress. Results In this study we propose a novel integrative approach for the analysis of metabolic networks to identify modules of joint shifts on the transcriptomic and metabolic levels. We derive a tardigrade-specific metabolic network represented as an undirected graph with 3,658 nodes (metabolites) and 4,378 edges (reactions). Time course metabolite profiles are used to score the network nodes showing a significant change over time. The edges are scored according to information on enzymes from the EST data. Using this combined information, we identify a key subnetwork (functional module) of concerted changes in metabolic pathways, specific for de- and rehydration. The module is enriched in reactions showing significant changes in metabolite levels and enzyme abundance during the transition. It resembles the cessation of a measurable metabolism (e.g. glycolysis and amino acid anabolism) during the tun formation, the production of storage metabolites and bioprotectants, such as DNA stabilizers, and the generation of amino acids and cellular components from monosaccharides as carbon and

  4. Reconstituted high-density lipoprotein infusion modulates fatty acid metabolism in patients with type 2 diabetes mellitus

    PubMed Central

    Drew, Brian G.; Carey, Andrew L.; Natoli, Alaina K.; Formosa, Melissa F.; Vizi, Donna; Reddy-Luthmoodoo, Medini; Weir, Jacquelyn M.; Barlow, Christopher K.; van Hall, Gerrit; Meikle, Peter J.; Duffy, Stephen J.; Kingwell, Bronwyn A.

    2011-01-01

    We recently demonstrated that reconstituted high-density lipoprotein (rHDL) modulates glucose metabolism in humans via both AMP-activated protein kinase (AMPK) in muscle and by increasing plasma insulin. Given the key roles of both AMPK and insulin in fatty acid metabolism, the current study investigated the effect of rHDL infusion on fatty acid oxidation and lipolysis. Thirteen patients with type 2 diabetes received separate infusions of rHDL and placebo in a randomized, cross-over study. Fatty acid metabolism was assessed using steady-state tracer methodology, and plasma lipids were measured by mass spectrometry (lipidomics). In vitro studies were undertaken in 3T3-L1 adipocytes. rHDL infusion inhibited fasting-induced lipolysis (P = 0.03), fatty acid oxidation (P < 0.01), and circulating glycerol (P = 0.04). In vitro, HDL inhibited adipocyte lipolysis in part via activation of AMPK, providing a possible mechanistic link for the apparent reductions in lipolysis observed in vivo. In contrast, circulating NEFA increased after rHDL infusion (P < 0.01). Lipidomic analyses implicated phospholipase hydrolysis of rHDL-associated phosphatidylcholine as the cause, rather than lipolysis of endogenous fat stores. rHDL infusion inhibits fasting-induced lipolysis and oxidation in patients with type 2 diabetes, potentially through both AMPK activation in adipose tissue and elevation of plasma insulin. The phospholipid component of rHDL also has the potentially undesirable effect of increasing circulating NEFA. PMID:21224289

  5. Andrographis paniculata Extract and Andrographolide Modulate the Hepatic Drug Metabolism System and Plasma Tolbutamide Concentrations in Rats

    PubMed Central

    Chen, Haw-Wen; Huang, Chin-Shiu; Liu, Pei-Fen; Li, Chien-Chun; Liu, Cheng-Tzu; Chiang, Jia-Rong; Yao, Hsien-Tsung; Lii, Chong-Kuei

    2013-01-01

    Andrographolide is the most abundant terpenoid of A. paniculata which is used in the treatment of diabetes. In this study, we investigated the effects of A. paniculata extract (APE) and andrographolide on the expression of drug-metabolizing enzymes in rat liver and determined whether modulation of these enzymes changed the pharmacokinetics of tolbutamide. Rats were intragastrically dosed with 2 g/kg/day APE or 50 mg/kg/day andrographolide for 5 days before a dose of 20 mg/kg tolbutamide was given. APE and andrographolide reduced the AUC0–12 h of tolbutamide by 37% and 18%, respectively, compared with that in controls. The protein and mRNA levels and enzyme activities of CYP2C6/11, CYP1A1/2, and CYP3A1/2 were increased by APE and andrographolide. To evaluate whether APE or andrographolide affected the hypoglycemic action of tolbutamide, high-fat diet-induced obese mice were used and treated in the same manner as the rats. APE and andrographolide increased CYP2C6/11 expression and decreased plasma tolbutamide levels. In a glucose tolerance test, however, the hypoglycemic effect of tolbutamide was not changed by APE or andrographolide. These results suggest that APE and andrographolide accelerate the metabolism rate of tolbutamide through increased expression and activity of drug-metabolizing enzymes. APE and andrographolide, however, do not impair the hypoglycemic effect of tolbutamide. PMID:23997806

  6. A Flavonoid Compound Promotes Neuronal Differentiation of Embryonic Stem Cells via PPAR-β Modulating Mitochondrial Energy Metabolism

    PubMed Central

    Mei, Yu-qin; Pan, Zong-fu; Chen, Wen-teng; Xu, Min-hua; Zhu, Dan-yan; Yu, Yong-ping; Lou, Yi-jia

    2016-01-01

    Relatively little is known regarding mitochondrial metabolism in neuronal differentiation of embryonic stem (ES) cells. By using a small molecule, present research has investigated the pattern of cellular energy metabolism in neural progenitor cells derived from mouse ES cells. Flavonoid compound 4a faithfully facilitated ES cells to differentiate into neurons morphologically and functionally. The expression and localization of peroxisome proliferator-activated receptors (PPARs) were examined in neural progenitor cells. PPAR-β expression showed robust upregulation compared to solvent control. Treatment with PPAR-β agonist L165041 alone or together with compound 4a significantly promoted neuronal differentiation, while antagonist GSK0660 blocked the neurogenesis-promoting effect of compound 4a. Consistently, knockdown of PPAR-β in ES cells abolished compound 4a-induced neuronal differentiation. Interestingly, we found that mitochondrial fusion protein Mfn2 was also abolished by sh-PPAR-β, resulting in abnormal mitochondrial Ca2+ ([Ca2+]M) transients as well as impaired mitochondrial bioenergetics. In conclusion, we demonstrated that by modulating mitochondrial energy metabolism through Mfn2 and mitochondrial Ca2+, PPAR-β took an important role in neuronal differentiation induced by flavonoid compound 4a. PMID:27315062

  7. A Flavonoid Compound Promotes Neuronal Differentiation of Embryonic Stem Cells via PPAR-β Modulating Mitochondrial Energy Metabolism.

    PubMed

    Mei, Yu-Qin; Pan, Zong-Fu; Chen, Wen-Teng; Xu, Min-Hua; Zhu, Dan-Yan; Yu, Yong-Ping; Lou, Yi-Jia

    2016-01-01

    Relatively little is known regarding mitochondrial metabolism in neuronal differentiation of embryonic stem (ES) cells. By using a small molecule, present research has investigated the pattern of cellular energy metabolism in neural progenitor cells derived from mouse ES cells. Flavonoid compound 4a faithfully facilitated ES cells to differentiate into neurons morphologically and functionally. The expression and localization of peroxisome proliferator-activated receptors (PPARs) were examined in neural progenitor cells. PPAR-β expression showed robust upregulation compared to solvent control. Treatment with PPAR-β agonist L165041 alone or together with compound 4a significantly promoted neuronal differentiation, while antagonist GSK0660 blocked the neurogenesis-promoting effect of compound 4a. Consistently, knockdown of PPAR-β in ES cells abolished compound 4a-induced neuronal differentiation. Interestingly, we found that mitochondrial fusion protein Mfn2 was also abolished by sh-PPAR-β, resulting in abnormal mitochondrial Ca2+ ([Ca2+]M) transients as well as impaired mitochondrial bioenergetics. In conclusion, we demonstrated that by modulating mitochondrial energy metabolism through Mfn2 and mitochondrial Ca2+, PPAR-β took an important role in neuronal differentiation induced by flavonoid compound 4a. PMID:27315062

  8. Altered surfactant protein A gene expression and protein metabolism associated with repeat exposure to inhaled endotoxin.

    PubMed

    George, Caroline L S; White, Misty L; O'Neill, Marsha E; Thorne, Peter S; Schwartz, David A; Snyder, Jeanne M

    2003-12-01

    Chronically inhaled endotoxin, which is ubiquitous in many occupational and domestic environments, can adversely affect the respiratory system resulting in an inflammatory response and decreased lung function. Surfactant-associated protein A (SP-A) is part of the lung innate immune system and may attenuate the inflammatory response in various types of lung injury. Using a murine model to mimic occupational exposures to endotoxin, we hypothesized that SP-A gene expression and protein would be elevated in response to repeat exposure to inhaled grain dust and to purified lipopolysaccharide (LPS). Our results demonstrate that repeat exposure to inhaled endotoxin, either in the form of grain dust or purified LPS, results in increased whole lung SP-A gene expression and type II alveolar epithelial cell hyperplasia, whereas SP-A protein levels in lung lavage fluid are decreased. Furthermore, these alterations in SP-A gene activity and protein metabolism are dependent on an intact endotoxin signaling system. PMID:12922979

  9. Viral and host proteins that modulate filovirus budding

    PubMed Central

    Liu, Yuliang; Harty, Ronald N

    2010-01-01

    The filoviruses, Ebola and Marburg, utilize a multifaceted mechanism for assembly and budding of infectious virions from mammalian cells. Growing evidence not only demonstrates the importance of multiple viral proteins for efficient assembly and budding, but also the exploitation of various host proteins/pathways by the virus during this late stage of filovirus replication, including endocytic compartments, vacuolar protein sorting pathways, ubiquitination machinery, lipid rafts and cytoskeletal components. Continued elucidation of these complex and orchestrated virus-host interactions will provide a fundamental understanding of the molecular mechanisms of filovirus assembly/budding and ultimately lead to the development of novel viral- and/or host-oriented therapeutics to inhibit filovirus egress and spread. This article will focus on the most recent studies on host interactions and modulation of filovirus budding and summarize the key findings from these investigations. PMID:20730024

  10. Mitochondria-targeted antioxidants and metabolic modulators as pharmacological interventions to slow ageing.

    PubMed

    Gruber, Jan; Fong, Sheng; Chen, Ce-Belle; Yoong, Sialee; Pastorin, Giorgia; Schaffer, Sebastian; Cheah, Irwin; Halliwell, Barry

    2013-01-01

    Populations in many nations today are rapidly ageing. This unprecedented demographic change represents one of the main challenges of our time. A defining property of the ageing process is a marked increase in the risk of mortality and morbidity with age. The incidence of cancer, cardiovascular and neurodegenerative diseases increases non-linearly, sometimes exponentially with age. One of the most important tasks in biogerontology is to develop interventions leading to an increase in healthy lifespan (health span), and a better understanding of basic mechanisms underlying the ageing process itself may lead to interventions able to delay or prevent many or even all age-dependent conditions. One of the putative basic mechanisms of ageing is age-dependent mitochondrial deterioration, closely associated with damage mediated by reactive oxygen species (ROS). Given the central role that mitochondria and mitochondrial dysfunction play not only in ageing but also in apoptosis, cancer, neurodegeneration and other age-related diseases there is great interest in approaches to protect mitochondria from ROS-mediated damage. In this review, we explore strategies of targeting mitochondria to reduce mitochondrial oxidative damage with the aim of preventing or delaying age-dependent decline in mitochondrial function and some of the resulting pathologies. We discuss mitochondria-targeted and -localized antioxidants (e.g.: MitoQ, SkQ, ergothioneine), mitochondrial metabolic modulators (e.g. dichloroacetic acid), and uncouplers (e.g.: uncoupling proteins, dinitrophenol) as well as some alternative future approaches for targeting compounds to the mitochondria, including advances from nanotechnology. PMID:23022622

  11. Yeast product supplementation modulated feeding behavior and metabolism in transition dairy cows.

    PubMed

    Yuan, K; Liang, T; Muckey, M B; Mendonça, L G D; Hulbert, L E; Elrod, C C; Bradford, B J

    2015-01-01

    Yeast supplementation has been shown to increase feed intake and production in some studies with early lactation dairy cows, but the mechanisms underlying such an effect remain unknown. The objective of this study was to assess the effects of supplementing a yeast product derived from Saccharomyces cerevisiae on production, feeding behavior, and metabolism in cows during the transition to lactation. Forty multiparous Holstein cows were blocked by expected calving date and randomly assigned within block to 1 of 4 treatments (n=10) from 21 d before expected calving to 42 d postpartum. Rations were top-dressed with a yeast culture plus enzymatically hydrolyzed yeast (YC-EHY; Celmanax, Vi-COR Inc., Mason City, IA) at the rate of 0, 30, 60, or 90g/d throughout the experiment. Dry matter and water intake, feeding behavior, and milk production were monitored. Plasma samples collected on -21, -7, 1, 4, 7, 14, 21, and 35 d relative to calving were analyzed for glucose, β-hydroxybutyrate, and nonesterified fatty acids. Data were analyzed using mixed models with repeated measures over time. Pre- or postpartum dry matter intake and water intake did not differ among treatments. Quadratic dose effects were observed for prepartum feeding behavior, reflecting decreased meal size, meal length, and intermeal interval, and increased meal frequency for cows received 30 and 60g/d of YC-EHY. Postpartum feeding behavior was unaffected by treatments. Milk yields were not affected (45.3, 42.6, 47.8, and 46.7kg/d for 0, 30, 60, and 90g/d, respectively) by treatments. Tendencies for increased percentages of milk fat, protein, and lactose were detected for cows receiving YC-EHY. Supplementing YC-EHY increased plasma β-hydroxybutyrate and tended to decrease (quadratic dose effect) glucose but did not affect nonesterified fatty acids. Yeast product supplementation during the transition period did not affect milk production and dry matter intake but modulated feeding behavior and metabolism

  12. Cell-specific modulation of surfactant proteins by ambroxol treatment.

    PubMed

    Seifart, Carola; Clostermann, Ursula; Seifart, Ulf; Müller, Bernd; Vogelmeier, Claus; von Wichert, Peter; Fehrenbach, Heinz

    2005-02-15

    Ambroxol [trans-4-(2-amino-3,5-dibromobenzylamino)-cyclohexanole hydrochloride], a mucolytic agent, was postulated to provide surfactant stimulatory properties and was previously used to prevent surfactant deficiency. Currently, the underlying mechanisms are not exactly clear. Because surfactant homeostasis is regulated by surfactant-specific proteins (SP), we analyzed protein amount and mRNA expression in whole lung tissue, isolated type II pneumocytes and bronchoalveolar lavage of Sprague-Dawley rats treated with ambroxol i.p. (75 mg/kg body weight, twice a day [every 12 h]). The methods used included competitive polymerase chain reaction (RT-PCR), Northern blotting, Western immunoblotting, and immunohistochemistry. In isolated type II pneumocytes of ambroxol-treated animals, SP-C protein and mRNA content were increased, whereas SP-A, -B and -D protein, mRNA, and immunoreactivity remained unaffected. However, ambroxol treatment resulted in a significant increase of SP-B and in a decrease of SP-D in whole lung tissue with enhanced immunostaining for SP-B in Clara Cells. SP-A and SP-D were significantly decreased in BAL fluid of ambroxol-treated animals. The data suggest that surfactant protein expression is modulated in a cell-specific manner by ambroxol, as type II pneumocytes exhibited an increase in SP-C, whereas Clara cells exhibited an increase in the immunoreactivity for SP-B accounting for the increased SP-B content of whole lung tissue. The results indicate that ambroxol may exert its positive effects, observed in the treatment of diseases related to surfactant deficiency, via modulation of surfactant protein expression. PMID:15694461

  13. Cell-specific modulation of surfactant proteins by ambroxol treatment

    SciTech Connect

    Seifart, Carola . E-mail: zwiebel@mailer.uni-marburg.de; Clostermann, Ursula; Seifart, Ulf

    2005-02-15

    Ambroxol [trans-4-(2-amino-3,5-dibromobenzylamino)-cyclohexanole hydrochloride], a mucolytic agent, was postulated to provide surfactant stimulatory properties and was previously used to prevent surfactant deficiency. Currently, the underlying mechanisms are not exactly clear. Because surfactant homeostasis is regulated by surfactant-specific proteins (SP), we analyzed protein amount and mRNA expression in whole lung tissue, isolated type II pneumocytes and bronchoalveolar lavage of Sprague-Dawley rats treated with ambroxol i.p. (75 mg/kg body weight, twice a day [every 12 h]). The methods used included competitive polymerase chain reaction (RT-PCR), Northern blotting, Western immunoblotting, and immunohistochemistry. In isolated type II pneumocytes of ambroxol-treated animals, SP-C protein and mRNA content were increased, whereas SP-A, -B and -D protein, mRNA, and immunoreactivity remained unaffected. However, ambroxol treatment resulted in a significant increase of SP-B and in a decrease of SP-D in whole lung tissue with enhanced immunostaining for SP-B in Clara Cells. SP-A and SP-D were significantly decreased in BAL fluid of ambroxol-treated animals. The data suggest that surfactant protein expression is modulated in a cell-specific manner by ambroxol, as type II pneumocytes exhibited an increase in SP-C, whereas Clara cells exhibited an increase in the immunoreactivity for SP-B accounting for the increased SP-B content of whole lung tissue. The results indicate that ambroxol may exert its positive effects, observed in the treatment of diseases related to surfactant deficiency, via modulation of surfactant protein expression.

  14. Functional modulation of G-protein coupled receptors during Parkinson disease-like neurodegeneration.

    PubMed

    Jenkins, Bruce G; Zhu, Aijun; Poutiainen, Pekka; Choi, Ji-Kyung; Kil, Kun-Eek; Zhang, Zhaoda; Kuruppu, Darshini; Aytan, Nurgul; Dedeoglu, Alpaslan; Brownell, Anna-Liisa

    2016-09-01

    G-protein coupled dopamine and metabotropic glutamate receptors (mGlu) can modulate neurotransmission during Parkinson's disease (PD)-like neurodegeneration. PET imaging studies in a unilateral dopamine denervation model (6-OHDA) showed a significant inverse correlation of presynaptic mGlu4 and postsynaptic mGlu5 expression in the striatum and rapidly declining mGlu4 and enhanced mGlu5 expression in the hippocampus during progressive degeneration over time. Immunohistochemical studies verified the decreased mGlu4 expression in the hippocampus on the lesion side but did not show difference in mGlu5 expression between lesion and control side. Pharmacological MRI studies showed enhanced hemodynamic response in several brain areas on the lesion side compared to the control side after challenge with mGlu4 positive allosteric modulator or mGlu5 negative allosteric modulator. However, mGlu4 response was biphasic having short enhancement followed by negative response on both sides of brain. Studies in mGlu4 expressing cells demonstrated that glutamate induces cooperative increase in binding of mGlu4 ligands - especially at high glutamate levels consistent with in vivo concentration. This suggests that mGlu allosteric modulators as drug candidates will be highly sensitive to changes in glutamate concentration and hence metabolic state. These experiments demonstrate the importance of the longitudinal imaging studies to investigate temporal changes in receptor functions to obtain individual response for experimental drugs. PMID:26581500

  15. Dietary Isoflavones as Modulators of Drug Metabolizing Enzymes and Transporters: Effect on Prescription Medicines.

    PubMed

    Taneja, Isha; Raju, Kanumuri Siva Rama; Wahajuddin, Muhammad

    2016-07-29

    Isoflavones are the most widely consumed phytoestrogens. Besides being a dietary constituent, their consumption has been increasing in the form of herbal supplements and as promising alternatives to hormonal replacement therapy, in conjunction with prescription medicines. Isoflavones are extensively metabolized by phase I and II enzymes and are substrates of drug transporters. At high concentrations isoflavones may interact with drug metabolizing enzymes and drug transporters and modulate their activity, thus, altering the absorption, metabolism, distribution, excretion and toxicity profile of the co-administered drugs. This review summarizes the up-to-date literature of isoflavone-drug interactions giving insight into the possible mechanisms of interactions, in vitro-in vivo correlation and their implications on clinical outcomes. PMID:26561312

  16. Enhancer-specific modulation of E protein activity.

    PubMed

    Markus, Maurice; Du, Zhimei; Benezra, Robert

    2002-02-22

    Homodimeric complexes of members of the E protein family of basic helix-loop-helix (bHLH) transcription factors are important for tissue-specific activation of genes in B lymphocytes (Bain, G., Gruenwald, S., and Murre, C. (1993) Mol. Cell Biol. 13, 3522-3529; Shen, C. P., and Kadesch, T. (1995) Mol. Cell Biol. 15, 4518-4524; Jacobs, Y., et al. (1994) Mol. Cell Biol. 14, 4087-4096; Wilson, R. B., et al. (1991) Mol. Cell Biol. 11, 6185-6191). These homodimers, however, have little activity on myogenic enhancers (Weintraub, H., Genetta, T., and Kadesch, T. (1994) Genes Dev. 8, 2203-2211). We report here the identification of a novel cis-acting transcriptional repression domain in the E protein family of bHLH transcription factors. This domain, the Rep domain, is present in each of the known vertebrate E proteins. Extensive mapping analysis demonstrates that this domain is an acidic region of 30 amino acids with a predicted loop structure. Fusion studies indicate that the Rep domain can repress both of the E protein transactivation domains (AD1 and AD2). Physiologically, the Rep domain plays a key role in maintaining E protein homodimers in an inactive state on myogenic enhancers. In addition, we demonstrate that Rep domain mediated repression of AD1 is a necessary for the function of MyoD-E protein heterodimeric complexes. These studies demonstrate that the Rep domain is important for modulating the transcriptional activity of E proteins and provide key insights into both the selectivity and mechanism of action of E protein containing bHLH protein complexes. PMID:11724804

  17. A new level of regulation in gluconeogenesis: metabolic state modulates the intracellular localization of aldolase B and its interaction with liver fructose-1,6-bisphosphatase.

    PubMed

    Droppelmann, Cristian A; Sáez, Doris E; Asenjo, Joel L; Yáñez, Alejandro J; García-Rocha, Mar; Concha, Ilona I; Grez, Manuel; Guinovart, Joan J; Slebe, Juan C

    2015-12-01

    Understanding how glucose metabolism is finely regulated at molecular and cellular levels in the liver is critical for knowing its relationship to related pathologies, such as diabetes. In order to gain insight into the regulation of glucose metabolism, we studied the liver-expressed isoforms aldolase B and fructose-1,6-bisphosphatase-1 (FBPase-1), key enzymes in gluconeogenesis, analysing their cellular localization in hepatocytes under different metabolic conditions and their protein-protein interaction in vitro and in vivo. We observed that glucose, insulin, glucagon and adrenaline differentially modulate the intracellular distribution of aldolase B and FBPase-1. Interestingly, the in vitro protein-protein interaction analysis between aldolase B and FBPase-1 showed a specific and regulable interaction between them, whereas aldolase A (muscle isozyme) and FBPase-1 showed no interaction. The affinity of the aldolase B and FBPase-1 complex was modulated by intermediate metabolites, but only in the presence of K(+). We observed a decreased association constant in the presence of adenosine monophosphate, fructose-2,6-bisphosphate, fructose-6-phosphate and inhibitory concentrations of fructose-1,6-bisphosphate. Conversely, the association constant of the complex increased in the presence of dihydroxyacetone phosphate (DHAP) and non-inhibitory concentrations of fructose-1,6-bisphosphate. Notably, in vivo FRET studies confirmed the interaction between aldolase B and FBPase-1. Also, the co-expression of aldolase B and FBPase-1 in cultured cells suggested that FBPase-1 guides the cellular localization of aldolase B. Our results provide further evidence that metabolic conditions modulate aldolase B and FBPase-1 activity at the cellular level through the regulation of their interaction, suggesting that their association confers a catalytic advantage for both enzymes. PMID:26417114

  18. A novel functional module detection algorithm for protein-protein interaction networks

    PubMed Central

    Hwang, Woochang; Cho, Young-Rae; Zhang, Aidong; Ramanathan, Murali

    2006-01-01

    Background The sparse connectivity of protein-protein interaction data sets makes identification of functional modules challenging. The purpose of this study is to critically evaluate a novel clustering technique for clustering and detecting functional modules in protein-protein interaction networks, termed STM. Results STM selects representative proteins for each cluster and iteratively refines clusters based on a combination of the signal transduced and graph topology. STM is found to be effective at detecting clusters with a diverse range of interaction structures that are significant on measures of biological relevance. The STM approach is compared to six competing approaches including the maximum clique, quasi-clique, minimum cut, betweeness cut and Markov Clustering (MCL) algorithms. The clusters obtained by each technique are compared for enrichment of biological function. STM generates larger clusters and the clusters identified have p-values that are approximately 125-fold better than the other methods on biological function. An important strength of STM is that the percentage of proteins that are discarded to create clusters is much lower than the other approaches. Conclusion STM outperforms competing approaches and is capable of effectively detecting both densely and sparsely connected, biologically relevant functional modules with fewer discards. PMID:17147822

  19. Contact sensitizers modulate the arachidonic acid metabolism of PMA-differentiated U-937 monocytic cells activated by LPS

    SciTech Connect

    Del Bufalo, Aurelia; Bernad, Jose; Dardenne, Christophe; Verda, Denis; Meunier, Jean Roch; Rousset, Francoise; Martinozzi-Teissier, Silvia; Pipy, Bernard

    2011-10-01

    For the effective induction of a hapten-specific T cell immune response toward contact sensitizers, in addition to covalent-modification of skin proteins, the redox and inflammatory statuses of activated dendritic cells are crucial. The aim of this study was to better understand how sensitizers modulate an inflammatory response through cytokines production and COX metabolism cascade. To address this purpose, we used the human monocytic-like U-937 cell line differentiated by phorbol myristate acetate (PMA) and investigated the effect of 6 contact sensitizers (DNCB, PPD, hydroquinone, propyl gallate, cinnamaldehyde and eugenol) and 3 non sensitizers (lactic acid, glycerol and tween 20) on the production of pro-inflammatory cytokines (IL-1{beta} and TNF-{alpha}) and on the arachidonic acid metabolic profile after bacterial lipopolysaccharide (LPS) stimulation. Our results showed that among the tested molecules, all sensitizers specifically prevent the production of PMA/LPS-induced COX-2 metabolites (PGE{sub 2,} TxB{sub 2} and PGD{sub 2}), eugenol and cinnamaldehyde inhibiting also the production of IL-1{beta} and TNF-{alpha}. We further demonstrated that there is no unique PGE{sub 2} inhibition mechanism: while the release of arachidonic acid (AA) from membrane phospholipids does not appear do be a target of modulation, COX-2 expression and/or COX-2 enzymatic activity are the major steps of prostaglandin synthesis that are inhibited by sensitizers. Altogether these results add a new insight into the multiple biochemical effects described for sensitizers. - Highlights: > We investigated how contact sensitizers modulate an inflammatory response. > We used macrophage-differentiated cell line, U-937 treated with PMA/LPS. > Sensitizers specifically inhibit the production of COX metabolites (PGE2, TxB2). > Several mechanisms of inhibition: COX-2 expression/enzymatic activity, isomerases. > New insight in the biochemical properties of sensitizers.

  20. Periodic and stochastic thermal modulation of protein folding kinetics

    SciTech Connect

    Platkov, Max; Gruebele, Martin

    2014-07-21

    Chemical reactions are usually observed either by relaxation of a bulk sample after applying a sudden external perturbation, or by intrinsic fluctuations of a few molecules. Here we show that the two ideas can be combined to measure protein folding kinetics, either by periodic thermal modulation, or by creating artificial thermal noise that greatly exceeds natural thermal fluctuations. We study the folding reaction of the enzyme phosphoglycerate kinase driven by periodic temperature waveforms. As the temperature waveform unfolds and refolds the protein, its fluorescence color changes due to FRET (Förster resonant Energy Transfer) of two donor/acceptor fluorophores labeling the protein. We adapt a simple model of periodically driven kinetics that nicely fits the data at all temperatures and driving frequencies: The phase shifts of the periodic donor and acceptor fluorescence signals as a function of driving frequency reveal reaction rates. We also drive the reaction with stochastic temperature waveforms that produce thermal fluctuations much greater than natural fluctuations in the bulk. Such artificial thermal noise allows the recovery of weak underlying signals due to protein folding kinetics. This opens up the possibility for future detection of a stochastic resonance for protein folding subject to noise with controllable amplitude.

  1. Periodic and stochastic thermal modulation of protein folding kinetics.

    PubMed

    Platkov, Max; Gruebele, Martin

    2014-07-21

    Chemical reactions are usually observed either by relaxation of a bulk sample after applying a sudden external perturbation, or by intrinsic fluctuations of a few molecules. Here we show that the two ideas can be combined to measure protein folding kinetics, either by periodic thermal modulation, or by creating artificial thermal noise that greatly exceeds natural thermal fluctuations. We study the folding reaction of the enzyme phosphoglycerate kinase driven by periodic temperature waveforms. As the temperature waveform unfolds and refolds the protein, its fluorescence color changes due to FRET (Förster resonant Energy Transfer) of two donor/acceptor fluorophores labeling the protein. We adapt a simple model of periodically driven kinetics that nicely fits the data at all temperatures and driving frequencies: The phase shifts of the periodic donor and acceptor fluorescence signals as a function of driving frequency reveal reaction rates. We also drive the reaction with stochastic temperature waveforms that produce thermal fluctuations much greater than natural fluctuations in the bulk. Such artificial thermal noise allows the recovery of weak underlying signals due to protein folding kinetics. This opens up the possibility for future detection of a stochastic resonance for protein folding subject to noise with controllable amplitude. PMID:25053342

  2. Periodic and stochastic thermal modulation of protein folding kinetics

    PubMed Central

    Platkov, Max; Gruebele, Martin

    2014-01-01

    Chemical reactions are usually observed either by relaxation of a bulk sample after applying a sudden external perturbation, or by intrinsic fluctuations of a few molecules. Here we show that the two ideas can be combined to measure protein folding kinetics, either by periodic thermal modulation, or by creating artificial thermal noise that greatly exceeds natural thermal fluctuations. We study the folding reaction of the enzyme phosphoglycerate kinase driven by periodic temperature waveforms. As the temperature waveform unfolds and refolds the protein, its fluorescence color changes due to FRET (Förster resonant Energy Transfer) of two donor/acceptor fluorophores labeling the protein. We adapt a simple model of periodically driven kinetics that nicely fits the data at all temperatures and driving frequencies: The phase shifts of the periodic donor and acceptor fluorescence signals as a function of driving frequency reveal reaction rates. We also drive the reaction with stochastic temperature waveforms that produce thermal fluctuations much greater than natural fluctuations in the bulk. Such artificial thermal noise allows the recovery of weak underlying signals due to protein folding kinetics. This opens up the possibility for future detection of a stochastic resonance for protein folding subject to noise with controllable amplitude. PMID:25053342

  3. Periodic and stochastic thermal modulation of protein folding kinetics

    NASA Astrophysics Data System (ADS)

    Platkov, Max; Gruebele, Martin

    2014-07-01

    Chemical reactions are usually observed either by relaxation of a bulk sample after applying a sudden external perturbation, or by intrinsic fluctuations of a few molecules. Here we show that the two ideas can be combined to measure protein folding kinetics, either by periodic thermal modulation, or by creating artificial thermal noise that greatly exceeds natural thermal fluctuations. We study the folding reaction of the enzyme phosphoglycerate kinase driven by periodic temperature waveforms. As the temperature waveform unfolds and refolds the protein, its fluorescence color changes due to FRET (Förster resonant Energy Transfer) of two donor/acceptor fluorophores labeling the protein. We adapt a simple model of periodically driven kinetics that nicely fits the data at all temperatures and driving frequencies: The phase shifts of the periodic donor and acceptor fluorescence signals as a function of driving frequency reveal reaction rates. We also drive the reaction with stochastic temperature waveforms that produce thermal fluctuations much greater than natural fluctuations in the bulk. Such artificial thermal noise allows the recovery of weak underlying signals due to protein folding kinetics. This opens up the possibility for future detection of a stochastic resonance for protein folding subject to noise with controllable amplitude.

  4. Testosterone Replacement Modulates Cardiac Metabolic Remodeling after Myocardial Infarction by Upregulating PPARα

    PubMed Central

    Yang, Jing

    2016-01-01

    Despite the importance of testosterone as a metabolic hormone, its effects on myocardial metabolism in the ischemic heart remain unclear. Myocardial ischemia leads to metabolic remodeling, ultimately resulting in ATP deficiency and cardiac dysfunction. In the present study, the effects of testosterone replacement on the ischemic heart were assessed in a castrated rat myocardial infarction model established by ligating the left anterior descending coronary artery 2 weeks after castration. The results of real-time PCR and Western blot analyses showed that peroxisome proliferator-activated receptor α (PPARα) decreased in the ischemic myocardium of castrated rats, compared with the sham-castration group, and the mRNA expression of genes involved in fatty acid metabolism (the fatty acid translocase CD36, carnitine palmitoyltransferase I, and medium-chain acyl-CoA dehydrogenase) and glucose transporter-4 also decreased. A decline in ATP levels in the castrated rats was accompanied by increased cardiomyocyte apoptosis and fibrosis and impaired cardiac function, compared with the sham-castration group, and these detrimental effects were reversed by testosterone replacement. Taken together, our findings suggest that testosterone can modulate myocardial metabolic remodeling by upregulating PPARα after myocardial infarction, exerting a protective effect on cardiac function. PMID:27413362

  5. miR-182 Regulates Metabolic Homeostasis by Modulating Glucose Utilization in Muscle.

    PubMed

    Zhang, Duo; Li, Yan; Yao, Xuan; Wang, Hui; Zhao, Lei; Jiang, Haowen; Yao, Xiaohan; Zhang, Shengjie; Ye, Cheng; Liu, Wei; Cao, Hongchao; Yu, Shuxian; Wang, Yu-Cheng; Li, Qiong; Jiang, Jingjing; Liu, Yi; Zhang, Ling; Liu, Yun; Iwai, Naoharu; Wang, Hui; Li, Jingya; Li, Jia; Li, Xihua; Jin, Zi-Bing; Ying, Hao

    2016-07-19

    Understanding the fiber-type specification and metabolic switch in skeletal muscle provides insights into energy metabolism in physiology and diseases. Here, we show that miR-182 is highly expressed in fast-twitch muscle and negatively correlates with blood glucose level. miR-182 knockout mice display muscle loss, fast-to-slow fiber-type switching, and impaired glucose metabolism. Mechanistic studies reveal that miR-182 modulates glucose utilization in muscle by targeting FoxO1 and PDK4, which control fuel selection via the pyruvate dehydrogenase complex (PDHC). Short-term high-fat diet (HFD) feeding reduces muscle miR-182 levels by tumor necrosis factor α (TNFα), which contributes to the upregulation of FoxO1/PDK4. Restoration of miR-182 expression in HFD-fed mice induces a faster muscle phenotype, decreases muscle FoxO1/PDK4 levels, and improves glucose metabolism. Together, our work establishes miR-182 as a critical regulator that confers robust and precise controls on fuel usage and glucose homeostasis. Our study suggests that a metabolic shift toward a faster and more glycolytic phenotype is beneficial for glucose control. PMID:27396327

  6. Introns regulate the production of ribosomal proteins by modulating splicing of duplicated ribosomal protein genes.

    PubMed

    Petibon, Cyrielle; Parenteau, Julie; Catala, Mathieu; Elela, Sherif Abou

    2016-05-01

    Most budding yeast introns exist in the many duplicated ribosomal protein genes (RPGs) and it has been posited that they remain there to modulate the expression of RPGs and cell growth in response to stress. However, the mechanism by which introns regulate the expression of RPGs and their impact on the synthesis of ribosomal proteins remain unclear. In this study, we show that introns determine the ratio of ribosomal protein isoforms through asymmetric paralog-specific regulation of splicing. Exchanging the introns and 3' untranslated regions of the duplicated RPS9 genes altered the splicing efficiency and changed the ratio of the ribosomal protein isoforms. Mutational analysis of the RPS9 genes indicated that splicing is regulated by variations in the intron structure and the 3' untranslated region. Together these data suggest that preferential splicing of duplicated RPGs provides a means for adjusting the ratio of different ribosomal protein isoforms, while maintaining the overall expression level of each ribosomal protein. PMID:26945043

  7. Effects of Tamarindus indica fruit pulp extract on abundance of HepG2 cell lysate proteins and their possible consequential impact on metabolism and inflammation.

    PubMed

    Chong, Ursula R W; Abdul-Rahman, Puteri S; Abdul-Aziz, Azlina; Hashim, Onn H; Mat-Junit, Sarni

    2013-01-01

    The fruit pulp extract of Tamarindus indica has been reported for its antioxidant and hypolipidemic properties. In this study, the methanol extract of T. indica fruit pulp was investigated for its effects on the abundance of HepG2 cell lysate proteins. Cell lysate was extracted from HepG2 cells grown in the absence and presence of the methanol extract of T. indica fruit pulp. Approximately 2500 spots were resolved using two-dimensional gel electrophoresis and the abundance of 20 cellular proteins was found to be significantly reduced. Among the proteins of reduced abundance, fourteen, including six proteins involved in metabolism (including ethanolamine phosphate cytidylyltransferase), four mitochondrial proteins (including prohibitin and respiratory chain proteins), and four proteins involved in translation and splicing, were positively identified by mass spectrometry and database search. The identified HepG2 altered abundance proteins, when taken together and analyzed by Ingenuity Pathways Analysis (IPA) software, are suggestive of the effects of T. indica fruit pulp extract on metabolism and inflammation, which are modulated by LXR/RXR. In conclusion, the methanol fruit pulp extract of T. indica was shown to cause reduced abundance of HepG2 mitochondrial, metabolic, and regulatory proteins involved in oxidative phosphorylation, protein synthesis, and cellular metabolism. PMID:24455694

  8. Effects of Tamarindus indica Fruit Pulp Extract on Abundance of HepG2 Cell Lysate Proteins and Their Possible Consequential Impact on Metabolism and Inflammation

    PubMed Central

    Chong, Ursula R. W.; Abdul-Rahman, Puteri S.; Abdul-Aziz, Azlina; Hashim, Onn H.; Mat-Junit, Sarni

    2013-01-01

    The fruit pulp extract of Tamarindus indica has been reported for its antioxidant and hypolipidemic properties. In this study, the methanol extract of T. indica fruit pulp was investigated for its effects on the abundance of HepG2 cell lysate proteins. Cell lysate was extracted from HepG2 cells grown in the absence and presence of the methanol extract of T. indica fruit pulp. Approximately 2500 spots were resolved using two-dimensional gel electrophoresis and the abundance of 20 cellular proteins was found to be significantly reduced. Among the proteins of reduced abundance, fourteen, including six proteins involved in metabolism (including ethanolamine phosphate cytidylyltransferase), four mitochondrial proteins (including prohibitin and respiratory chain proteins), and four proteins involved in translation and splicing, were positively identified by mass spectrometry and database search. The identified HepG2 altered abundance proteins, when taken together and analyzed by Ingenuity Pathways Analysis (IPA) software, are suggestive of the effects of T. indica fruit pulp extract on metabolism and inflammation, which are modulated by LXR/RXR. In conclusion, the methanol fruit pulp extract of T. indica was shown to cause reduced abundance of HepG2 mitochondrial, metabolic, and regulatory proteins involved in oxidative phosphorylation, protein synthesis, and cellular metabolism. PMID:24455694

  9. A principal mechanism for the cancer chemopreventive activity of phenethyl isothiocyanate is modulation of carcinogen metabolism.

    PubMed

    Ioannides, Costas; Konsue, Nattaya

    2015-08-01

    Isothiocyanates are small molecules characterized by high chemical reactivity that allows them to interact readily with cellular constituents eliciting a plethora of biological activities. They are present exclusively in cruciferous vegetables, as glucosinolates, the intake of which has been associated with cancer chemoprevention. When the physical structure of these vegetables is disturbed, e.g. during mastication, the enzyme myrosinase is released and converts the glucosinolates to isothiocyanates (R-N=C=S), where R can be aliphatic or aromatic. Although sulforaphane, an aliphatic isothiocyanate, has received most attention worldwide, the most extensively studied aromatic isothiocyanate is phenethyl isothiocyanate (PEITC), and there are substantial differences in biological activity between the two sub-classes. In animal cancer models, PEITC effectively antagonized the carcinogenicity of chemicals, especially nitrosocompounds. A principal mechanism of their action is to protect the integrity of DNA by decreasing the levels of the genotoxic metabolites of chemical carcinogens. Extensive studies established that PEITC modulates the metabolism of the tobacco-specific carcinogenic nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) by inhibiting its cytochrome P450-mediated bioactivation. Moreover, PEITC is a potent inducer of detoxification enzymes such as quinone reductase, glutathione S-transferase and glucuronosyl transferase. PEITC is rapidly absorbed and is characterized by a large bioavailability; Cmax concentrations achieved in plasma after dietary intake are sufficient to modulate carcinogen metabolism. PEITC is primarily metabolized by glutathione conjugation and is excreted in the urine and bile as the mercapturate. The ability of PEITC to perturb carcinogen metabolism through modulation of cytochrome P450 and phase II detoxification enzymes is comprehensively and critically reviewed. PMID:26119477

  10. Quantitative Proteomics Analysis Reveals the Min System of Escherichia coli Modulates Reversible Protein Association with the Inner Membrane.

    PubMed

    Lee, Hsiao-Lin; Chiang, I-Chen; Liang, Suh-Yuen; Lee, Der-Yen; Chang, Geen-Dong; Wang, Kwan-Yu; Lin, Shu-Yu; Shih, Yu-Ling

    2016-05-01

    The Min system of Escherichia coli mediates placement of the division septum at the midcell. It oscillates from pole to pole to establish a concentration gradient of the division inhibition that is high at the poles but low at the midcell; the cell middle thereby becomes the most favorable site for division. Although Min oscillation is well studied from molecular and biophysical perspectives, it is still an enigma as to whether such a continuous, energy-consuming, and organized movement of the Min proteins would affect cellular processes other than the division site selection. To tackle this question, we compared the inner membrane proteome of the wild-type and Δmin strains using a quantitative approach. Forty proteins that showed differential abundance on the inner membrane of the mutant cells were identified and defined as proteins of interest (POIs). More than half of the POIs were peripheral membrane proteins, suggesting that the Min system affects mainly reversible protein association with the inner membrane. In addition, 6 out of 10 selected POIs directly interacted with at least one of the Min proteins, confirming the correlation between POIs and the Min system.Further analysis revealed a functional relationship between metabolism and the Min system. Metabolic enzymes accounted for 45% of the POIs, and there was a change of metabolites in the related reactions. We hypothesize that the Min system could alter the membrane location of proteins to modulate their enzymatic activity. Thus, the metabolic modulation in the Δmin mutant is likely an adaptive phenotype in cells of abnormal size and chromosome number due to an imbalanced abundance of proteins on the inner membrane. Taken together, the current work reports novel interactions of the Min system and reveals a global physiological impact of the Min system in addition to the division site placement. PMID:26889046

  11. Impact of Dietary Carbohydrate and Protein Levels on Carbohydrate Metabolism

    ERIC Educational Resources Information Center

    Lasker, Denise Ann

    2009-01-01

    The goal of this dissertation was to investigate the impact of changing dietary carbohydrate (CARB) intakes within recommended dietary guidelines on metabolic outcomes specifically associated with glycemic regulations and carbohydrate metabolism. This research utilized both human and animal studies to examine changes in metabolism across a wide…

  12. Amyloid Precursor Protein Expression Modulates Intestine Immune Phenotype

    PubMed Central

    Puig, Kendra L.; Swigost, Adam J.; Zhou, Xudong; Sens, MaryAnn; Combs, Colin K.

    2014-01-01

    Amyloid precursor protein (APP) is widely expressed across many tissue and cell types. Proteolytic processing of the protein gives rise to a plethora of protein fragments with varied biological activities. Although a large amount of data has been generated describing the metabolism of the protein in neurons, its role in regulating the phenotype of other cells remains unclear. Based upon prior work demonstrating that APP regulates the activation phenotype of monocytic lineage cells, we hypothesized that APP can regulate macrophage activation phenotype in tissues other than brain. Ileums of the small intestines from C57BL6/J wild type and APP−/− mice were compared as a representative tissue normally associated with abundant macrophage infiltration. APP−/− intestines demonstrated diminished CD68 immunoreactivity compared to wild type mice. This correlated with significantly less cycloxygenase-2 (cox-2), CD68, CD40, CD11c, and βIII-tubulin protein levels. Peritoneal macrophage from APP−/− mice demonstrated decreased in vitro migratory ability compared to wild type cells and diminished basal KC cytokine secretion. Whereas, APP−/− intestinal macrophage had an increase in basal KC cytokine secretion compared to wild type cells. Conversely, there was a significant decrease in multiple cytokine levels in APP−/− compared to wild type ileums. Finally, APP−/− mice demonstrated impaired absorption and increased motility compared to wild type mice. These data demonstrate the APP expression regulates immune cell secretions and phenotype and intestinal function. This data set describes a novel function for this protein or its metabolites that may be relevant not only for Alzheimer’s disease but a range of immune-related disorders. PMID:22124967

  13. Starch Granule Re-Structuring by Starch Branching Enzyme and Glucan Water Dikinase Modulation Affects Caryopsis Physiology and Metabolism

    PubMed Central

    Shaik, Shahnoor S.; Obata, Toshihiro; Hebelstrup, Kim H.; Schwahn, Kevin; Fernie, Alisdair R.; Mateiu, Ramona V.; Blennow, Andreas

    2016-01-01

    Starch is of fundamental importance for plant development and reproduction and its optimized molecular assembly is potentially necessary for correct starch metabolism. Re-structuring of starch granules in-planta can therefore potentially affect plant metabolism. Modulation of granule micro-structure was achieved by decreasing starch branching and increasing starch-bound phosphate content in the barley caryopsis starch by RNAi suppression of all three Starch Branching Enzyme (SBE) isoforms or overexpression of potato Glucan Water Dikinase (GWD). The resulting lines displayed Amylose-Only (AO) and Hyper-Phosphorylated (HP) starch chemotypes, respectively. We studied the influence of these alterations on primary metabolism, grain composition, starch structural features and starch granule morphology over caryopsis development at 10, 20 and 30 days after pollination (DAP) and at grain maturity. While HP showed relatively little effect, AO showed significant reduction in starch accumulation with re-direction to protein and β-glucan (BG) accumulation. Metabolite profiling indicated significantly higher sugar accumulation in AO, with re-partitioning of carbon to accumulate amino acids, and interestingly it also had high levels of some important stress-related metabolites and potentially protective metabolites, possibly to elude deleterious effects. Investigations on starch molecular structure revealed significant increase in starch phosphate and amylose content in HP and AO respectively with obvious differences in starch granule morphology at maturity. The results demonstrate that decreasing the storage starch branching resulted in metabolic adjustments and re-directions, tuning to evade deleterious effects on caryopsis physiology and plant performance while only little effect was evident by increasing starch-bound phosphate as a result of overexpressing GWD. PMID:26891365

  14. Starch Granule Re-Structuring by Starch Branching Enzyme and Glucan Water Dikinase Modulation Affects Caryopsis Physiology and Metabolism.

    PubMed

    Shaik, Shahnoor S; Obata, Toshihiro; Hebelstrup, Kim H; Schwahn, Kevin; Fernie, Alisdair R; Mateiu, Ramona V; Blennow, Andreas

    2016-01-01

    Starch is of fundamental importance for plant development and reproduction and its optimized molecular assembly is potentially necessary for correct starch metabolism. Re-structuring of starch granules in-planta can therefore potentially affect plant metabolism. Modulation of granule micro-structure was achieved by decreasing starch branching and increasing starch-bound phosphate content in the barley caryopsis starch by RNAi suppression of all three Starch Branching Enzyme (SBE) isoforms or overexpression of potato Glucan Water Dikinase (GWD). The resulting lines displayed Amylose-Only (AO) and Hyper-Phosphorylated (HP) starch chemotypes, respectively. We studied the influence of these alterations on primary metabolism, grain composition, starch structural features and starch granule morphology over caryopsis development at 10, 20 and 30 days after pollination (DAP) and at grain maturity. While HP showed relatively little effect, AO showed significant reduction in starch accumulation with re-direction to protein and β-glucan (BG) accumulation. Metabolite profiling indicated significantly higher sugar accumulation in AO, with re-partitioning of carbon to accumulate amino acids, and interestingly it also had high levels of some important stress-related metabolites and potentially protective metabolites, possibly to elude deleterious effects. Investigations on starch molecular structure revealed significant increase in starch phosphate and amylose content in HP and AO respectively with obvious differences in starch granule morphology at maturity. The results demonstrate that decreasing the storage starch branching resulted in metabolic adjustments and re-directions, tuning to evade deleterious effects on caryopsis physiology and plant performance while only little effect was evident by increasing starch-bound phosphate as a result of overexpressing GWD. PMID:26891365

  15. Insulin sensitivity of muscle protein metabolism is altered in patients with chronic kidney disease and metabolic acidosis

    PubMed Central

    Garibotto, Giacomo; Sofia, Antonella; Russo, Rodolfo; Paoletti, Ernesto; Bonanni, Alice; Parodi, Emanuele L; Viazzi, Francesca; Verzola, Daniela

    2015-01-01

    An emergent hypothesis is that a resistance to the anabolic drive by insulin may contribute to loss of strength and muscle mass in patients with chronic kidney disease (CKD). We tested whether insulin resistance extends to protein metabolism using the forearm perfusion method with arterial insulin infusion in 7 patients with CKD and metabolic acidosis (bicarbonate 19 mmol/l) and 7 control individuals. Forearm glucose balance and protein turnover (2H-phenylalanine kinetics) were measured basally and in response to insulin infused at different rates for 2 h to increase local forearm plasma insulin concentration by approximately 20 and 50 μU/ml. In response to insulin, forearm glucose uptake was significantly increased to a lesser extent (−40%) in patients with CKD than controls. In addition, whereas in the controls net muscle protein balance and protein degradation were decreased by both insulin infusion rates, in patients with CKD net protein balance and protein degradation were sensitive to the high (0.035 mU/kg per min) but not the low (0.01 mU/kg per min) insulin infusion. Besides blunting muscle glucose uptake, CKD and acidosis interfere with the normal suppression of protein degradation in response to a moderate rise in plasma insulin. Thus, alteration of protein metabolism by insulin may lead to changes in body tissue composition which may become clinically evident in conditions characterized by low insulinemia. PMID:26308671

  16. Nur77 modulates hepatic lipid metabolism through suppression of SREBP1c activity

    SciTech Connect

    Pols, Thijs W.H.; Ottenhoff, Roelof; Vos, Mariska; Levels, Johannes H.M.; Quax, Paul H.A.; Meijers, Joost C.M.; Pannekoek, Hans; Groen, Albert K.; Vries, Carlie J.M. de

    2008-02-22

    NR4A nuclear receptors are induced in the liver upon fasting and regulate hepatic gluconeogenesis. Here, we studied the role of nuclear receptor Nur77 (NR4A1) in hepatic lipid metabolism. We generated mice expressing hepatic Nur77 using adenoviral vectors, and demonstrate that these mice exhibit a modulation of the plasma lipid profile and a reduction in hepatic triglyceride. Expression analysis of >25 key genes involved in lipid metabolism revealed that Nur77 inhibits SREBP1c expression. This results in decreased SREBP1c activity as is illustrated by reduced expression of its target genes stearoyl-coA desaturase-1, mitochondrial glycerol-3-phosphate acyltransferase, fatty acid synthase and the LDL receptor, and provides a mechanism for the physiological changes observed in response to Nur77. Expression of LXR target genes Abcg5 and Abcg8 is reduced by Nur77, and may suggest involvement of LXR in the inhibitory action of Nur77 on SREBP1c expression. Taken together, our study demonstrates that Nur77 modulates hepatic lipid metabolism through suppression of SREBP1c activity.

  17. System-wide assembly of pathways and modules hierarchically reveal metabolic mechanism of cerebral ischemia

    PubMed Central

    Zhu, Yan; Guo, Zhili; Zhang, Liangxiao; Zhang, Yingying; Chen, Yinying; Nan, Jingyi; Zhao, Buchang; Xiao, Hongbin; Wang, Zhong; Wang, Yongyan

    2015-01-01

    The relationship between cerebral ischemia and metabolic disorders is poorly understood, which is partly due to the lack of comparative fusing data for larger complete systems and to the complexity of metabolic cascade reactions. Based on the fusing maps of comprehensive serum metabolome, fatty acid and amino acid profiling, we identified 35 potential metabolic biomarkers for ischemic stroke. Our analyses revealed 8 significantly altered pathways by MetPA (Metabolomics Pathway Analysis, impact score >0.10) and 15 significantly rewired modules in a complex ischemic network using the Markov clustering (MCL) method; all of these pathways became more homologous as the number of overlapping nodes was increased. We then detected 24 extensive pathways based on the total modular nodes from the network analysis, 12 of which were new discovery pathways. We provided a new perspective from the viewpoint of abnormal metabolites for the overall study of ischemic stroke as well as a new method to simplify the network analysis by selecting the more closely connected edges and nodes to build a module map of stroke. PMID:26621314

  18. Assessing the Metabolic Diversity of Streptococcus from a Protein Domain Point of View

    PubMed Central

    Koehorst, Jasper J.; Martins dos Santos, Vitor A. P.; Schaap, Peter J.

    2015-01-01

    Understanding the diversity and robustness of the metabolism of bacteria is fundamental for understanding how bacteria evolve and adapt to different environments. In this study, we characterised 121 Streptococcus strains and studied metabolic diversity from a protein domain perspective. Metabolic pathways were described in terms of the promiscuity of domains participating in metabolic pathways that were inferred to be functional. Promiscuity was defined by adapting existing measures based on domain abundance and versatility. The approach proved to be successful in capturing bacterial metabolic flexibility and species diversity, indicating that it can be described in terms of reuse and sharing functional domains in different proteins involved in metabolic activity. Additionally, we showed striking differences among metabolic organisation of the pathogenic serotype 2 Streptococcus suis and other strains. PMID:26366735

  19. Discovery, Synthesis and Biological Evaluation of Novel SMN Protein Modulators

    PubMed Central

    Xiao, Jingbo; Marugan, Juan J.; Zheng, Wei; Titus, Steve; Southall, Noel; Cherry, Jonathan J.; Evans, Matthew; Androphy, Elliot J.; Austin, Christopher P.

    2011-01-01

    Spinal Muscular Atrophy (SMA) is an autosomal recessive disorder affecting the expression or function of survival motor neuron protein (SMN) due to the homozygous deletion or rare point mutations in the survival motor neuron gene 1 (SMN1). The human genome includes a second nearly identical gene called SMN2 that is retained in SMA. SMN2 transcripts undergo alternative splicing with reduced levels of SMN. Up-regulation of SMN2 expression, modification of its splicing, or inhibition of proteolysis of the truncated protein derived from SMN2 have been discussed as potential therapeutic strategies for SMA. In this manuscript, we detail the discovery of a series of arylpiperidines as novel modulators of SMN protein. Systematic hit-to-lead efforts significantly improved potency and efficacy of the series in the primary and orthogonal assays. Structure property relationships including microsomal stability, cell permeability and in vivo pharmacokinetics (PK) studies were also investigated. We anticipate that a lead candidate chosen from this series may serve as a useful probe for exploring the therapeutic benefits of SMN protein up-regulation in SMA animal models, and a starting point for clinical development. PMID:21819082

  20. Capacitance-modulated transistor detects odorant binding protein chiral interactions.

    PubMed

    Mulla, Mohammad Yusuf; Tuccori, Elena; Magliulo, Maria; Lattanzi, Gianluca; Palazzo, Gerardo; Persaud, Krishna; Torsi, Luisa

    2015-01-01

    Peripheral events in olfaction involve odorant binding proteins (OBPs) whose role in the recognition of different volatile chemicals is yet unclear. Here we report on the sensitive and quantitative measurement of the weak interactions associated with neutral enantiomers differentially binding to OBPs immobilized through a self-assembled monolayer to the gate of an organic bio-electronic transistor. The transduction is remarkably sensitive as the transistor output current is governed by the small capacitance of the protein layer undergoing minute changes as the ligand-protein complex is formed. Accurate determination of the free-energy balances and of the capacitance changes associated with the binding process allows derivation of the free-energy components as well as of the occurrence of conformational events associated with OBP ligand binding. Capacitance-modulated transistors open a new pathway for the study of ultra-weak molecular interactions in surface-bound protein-ligand complexes through an approach that combines bio-chemical and electronic thermodynamic parameters. PMID:25591754

  1. Capacitance-modulated transistor detects odorant binding protein chiral interactions

    NASA Astrophysics Data System (ADS)

    Mulla, Mohammad Yusuf; Tuccori, Elena; Magliulo, Maria; Lattanzi, Gianluca; Palazzo, Gerardo; Persaud, Krishna; Torsi, Luisa

    2015-01-01

    Peripheral events in olfaction involve odorant binding proteins (OBPs) whose role in the recognition of different volatile chemicals is yet unclear. Here we report on the sensitive and quantitative measurement of the weak interactions associated with neutral enantiomers differentially binding to OBPs immobilized through a self-assembled monolayer to the gate of an organic bio-electronic transistor. The transduction is remarkably sensitive as the transistor output current is governed by the small capacitance of the protein layer undergoing minute changes as the ligand-protein complex is formed. Accurate determination of the free-energy balances and of the capacitance changes associated with the binding process allows derivation of the free-energy components as well as of the occurrence of conformational events associated with OBP ligand binding. Capacitance-modulated transistors open a new pathway for the study of ultra-weak molecular interactions in surface-bound protein-ligand complexes through an approach that combines bio-chemical and electronic thermodynamic parameters.

  2. Metabolic syndrome and C-reactive protein in bank employees

    PubMed Central

    Cattafesta, Monica; Bissoli, Nazaré Souza; Salaroli, Luciane Bresciani

    2016-01-01

    Background The ultrasensitive C-reactive protein (us-CRP) is used for the diagnosis of cardiovascular disease, but it is not well described as a marker for the diagnosis of metabolic syndrome (MS). Methods An observational and transversal study of bank employees evaluated anthropometric, hemodynamic, and biochemical data. CRP values were determined using commercial kits from Roche Diagnostics Ltd, and MS criteria were analyzed according to National Cholesterol Education Program’s – Adult Treatment Panel III (NCEP/ATP III). Results A total of 88 individuals had MS, and 77.3% (n=68) of these showed alterations of us-CRP (P=0.0001, confidence interval [CI] 0.11–0.34). Individuals with MS had higher mean values of us-CRP in global measures (P=0.0001) and stratified by sex (P=0.004) than individuals without the syndrome. This marker exhibited significant differences with varying criteria for MS, such as waist circumference (P=0.0001), triglycerides (P=0.002), and diastolic blood pressure (P=0.007), and the highest levels of us-CRP were found in individuals with more MS criteria. Conclusion us-CRP was strongly associated with the presence of MS and MS criteria in this group of workers. us-CRP is a useful and effective marker for identifying the development of MS and may be used as a reference in routine care. PMID:27274294

  3. Analysis of Candida albicans Mutants Defective in the Cdk8 Module of Mediator Reveal Links between Metabolism and Biofilm Formation

    PubMed Central

    Lindsay, Allia K.; Morales, Diana K.; Liu, Zhongle; Grahl, Nora; Zhang, Anda; Willger, Sven D.; Myers, Lawrence C.; Hogan, Deborah A.

    2014-01-01

    Candida albicans biofilm formation is a key virulence trait that involves hyphal growth and adhesin expression. Pyocyanin (PYO), a phenazine secreted by Pseudomonas aeruginosa, inhibits both C. albicans biofilm formation and development of wrinkled colonies. Using a genetic screen, we identified two mutants, ssn3Δ/Δ and ssn8Δ/Δ, which continued to wrinkle in the presence of PYO. Ssn8 is a cyclin-like protein and Ssn3 is similar to cyclin-dependent kinases; both proteins are part of the heterotetrameric Cdk8 module that forms a complex with the transcriptional co-regulator, Mediator. Ssn3 kinase activity was also required for PYO sensitivity as a kinase dead mutant maintained a wrinkled colony morphology in the presence of PYO. Furthermore, similar phenotypes were observed in mutants lacking the other two components of the Cdk8 module—Srb8 and Srb9. Through metabolomics analyses and biochemical assays, we showed that a compromised Cdk8 module led to increases in glucose consumption, glycolysis-related transcripts, oxidative metabolism and ATP levels even in the presence of PYO. In the mutant, inhibition of respiration to levels comparable to the PYO-treated wild type inhibited wrinkled colony development. Several lines of evidence suggest that PYO does not act through Cdk8. Lastly, the ssn3 mutant was a hyperbiofilm former, and maintained higher biofilm formation in the presence of PYO than the wild type. Together these data provide novel insights into the role of the Cdk8 module of Mediator in regulation of C. albicans physiology and the links between respiratory activity and both wrinkled colony and biofilm development. PMID:25275466

  4. Comparative Proteomics Provides Insights into Metabolic Responses in Rat Liver to Isolated Soy and Meat Proteins.

    PubMed

    Song, Shangxin; Hooiveld, Guido J; Zhang, Wei; Li, Mengjie; Zhao, Fan; Zhu, Jing; Xu, Xinglian; Muller, Michael; Li, Chunbao; Zhou, Guanghong

    2016-04-01

    It has been reported that isolated dietary soy and meat proteins have distinct effects on physiology and liver gene expression, but the impact on protein expression responses are unknown. Because these may differ from gene expression responses, we investigated dietary protein-induced changes in liver proteome. Rats were fed for 1 week semisynthetic diets that differed only regarding protein source; casein (reference) was fully replaced by isolated soy, chicken, fish, or pork protein. Changes in liver proteome were measured by iTRAQ labeling and LC-ESI-MS/MS. A robust set totaling 1437 unique proteins was identified and subjected to differential protein analysis and biological interpretation. Compared with casein, all other protein sources reduced the abundance of proteins involved in fatty acid metabolism and Pparα signaling pathway. All dietary proteins, except chicken, increased oxidoreductive transformation reactions but reduced energy and essential amino acid metabolic pathways. Only soy protein increased the metabolism of sulfur-containing and nonessential amino acids. Soy and fish proteins increased translation and mRNA processing, whereas only chicken protein increased TCA cycle but reduced immune responses. These findings were partially in line with previously reported transcriptome results. This study further shows the distinct effects of soy and meat proteins on liver metabolism in rats. PMID:26886706

  5. Endogenous heparan sulfate and heparin modulate bone morphogenetic protein-4 signaling and activity.

    PubMed

    Khan, Shaukat A; Nelson, Matthew S; Pan, Chendong; Gaffney, Patrick M; Gupta, Pankaj

    2008-06-01

    Bone morphogenetic proteins (BMPs) and their endogenous antagonists are important for brain and bone development and tumor initiation and progression. Heparan sulfate (HS) proteoglycans (HSPG) modulate the activities of BMPs and their antagonists. How glycosaminoglycans (GAGs) influence BMP activity in various malignancies and in inherited abnormalities of GAG metabolism, and the structural features of GAGs essential for modulation of BMP signaling, remain incompletely defined. We examined whether chemically modified soluble heparins, the endogenous HS in malignant cells and the HS accumulated in Hurler syndrome cells influence BMP-4 signaling and activity. We show that both exogenous (soluble) and endogenous GAGs modulate BMP-4 signaling and activity, and that this effect is dependent on specific sulfate residues of GAGs. Our studies suggest that endogenous sulfated GAGs promote the proliferation and impair differentiation of malignant human cells, providing the rationale for investigating whether pharmacological agents that inhibit GAG synthesis or function might reverse this effect. Our demonstration of impairment of BMP-4 signaling by GAGs in multipotent stem cells in human Hurler syndrome identifies a mechanism that might contribute to the progressive neurological and skeletal abnormalities in Hurler syndrome and related mucopolysaccharidoses. PMID:18385288

  6. Acetylation of glucokinase regulatory protein decreases glucose metabolism by suppressing glucokinase activity

    PubMed Central

    Park, Joo-Man; Kim, Tae-Hyun; Jo, Seong-Ho; Kim, Mi-Young; Ahn, Yong-Ho

    2015-01-01

    Glucokinase (GK), mainly expressed in the liver and pancreatic β-cells, is critical for maintaining glucose homeostasis. GK expression and kinase activity, respectively, are both modulated at the transcriptional and post-translational levels. Post-translationally, GK is regulated by binding the glucokinase regulatory protein (GKRP), resulting in GK retention in the nucleus and its inability to participate in cytosolic glycolysis. Although hepatic GKRP is known to be regulated by allosteric mechanisms, the precise details of modulation of GKRP activity, by post-translational modification, are not well known. Here, we demonstrate that GKRP is acetylated at Lys5 by the acetyltransferase p300. Acetylated GKRP is resistant to degradation by the ubiquitin-dependent proteasome pathway, suggesting that acetylation increases GKRP stability and binding to GK, further inhibiting GK nuclear export. Deacetylation of GKRP is effected by the NAD+-dependent, class III histone deacetylase SIRT2, which is inhibited by nicotinamide. Moreover, the livers of db/db obese, diabetic mice also show elevated GKRP acetylation, suggesting a broader, critical role in regulating blood glucose. Given that acetylated GKRP may affiliate with type-2 diabetes mellitus (T2DM), understanding the mechanism of GKRP acetylation in the liver could reveal novel targets within the GK-GKRP pathway, for treating T2DM and other metabolic pathologies. PMID:26620281

  7. Metabolic syndrome-related hepatocellular carcinoma treated by volumetric modulated arc therapy.

    PubMed

    Klein, J; Dawson, L A; Tran, T H; Adeyi, O; Purdie, T; Sherman, M; Brade, A

    2014-04-01

    Hepatocellular carcinoma (hcc) is a leading cause of cancer mortality, and its incidence is increasing in developed countries. Risk factors include cirrhosis from viral hepatitis or alcohol abuse. Metabolic syndrome is a newly recognized, but important, risk factor that is likely contributing to the increased incidence of hcc. Surgery is the therapy of choice for hcc, but local therapies are often contraindicated, usually because of advanced disease or comorbid conditions such as cardiac disease (which is associated with metabolic syndrome). Current radiation therapy techniques such as stereotactic body radiotherapy allow for treatment plans that highly conform to the target and provide excellent sparing of normal structures. Radiation therapy is emerging as a viable option in patients not eligible for surgery or other locoregional therapies. Here, we report a case of a large hcc presenting in a patient with metabolic syndrome without significant alcohol history or biochemical liver dysfunction. The patient was not a candidate for locoregional therapies because of cardiac and renal comorbidities typical of patients experiencing the long-term sequelae of metabolic syndrome. Treatment using an arc-based volumetric-modulated arc therapy technique allowed for the highest dose of radiation to be delivered to the tumour while the peripheral radiation dose was minimized. A complete local response was confirmed by computed tomography imaging 21 months after treatment completion. PMID:24764717

  8. Insulin Is a Key Modulator of Fetoplacental Endothelium Metabolic Disturbances in Gestational Diabetes Mellitus

    PubMed Central

    Sobrevia, Luis; Salsoso, Rocío; Fuenzalida, Bárbara; Barros, Eric; Toledo, Lilian; Silva, Luis; Pizarro, Carolina; Subiabre, Mario; Villalobos, Roberto; Araos, Joaquín; Toledo, Fernando; González, Marcelo; Gutiérrez, Jaime; Farías, Marcelo; Chiarello, Delia I.; Pardo, Fabián; Leiva, Andrea

    2016-01-01

    Gestational diabetes mellitus (GDM) is a disease of the mother that associates with altered fetoplacental vascular function. GDM-associated maternal hyperglycaemia result in fetal hyperglycaemia, a condition that leads to fetal hyperinsulinemia and altered L-arginine transport and synthesis of nitric oxide, i.e., endothelial dysfunction. These alterations in the fetoplacental endothelial function are present in women with GDM that were under diet or insulin therapy. Since these women and their newborn show normal glycaemia at term, other factors or conditions could be altered and/or not resolved by restoring normal level of circulating D-glucose. GDM associates with metabolic disturbances, such as abnormal handling of the locally released vasodilator adenosine, and biosynthesis and metabolism of cholesterol lipoproteins, or metabolic diseases resulting in endoplasmic reticulum stress and altered angiogenesis. Insulin acts as a potent modulator of all these phenomena under normal conditions as reported in primary cultures of cells obtained from the human placenta; however, GDM and the role of insulin regarding these alterations in this disease are poorly understood. This review focuses on the potential link between insulin and endoplasmic reticulum stress, hypercholesterolemia, and angiogenesis in GDM in the human fetoplacental vasculature. Based in reports in primary culture placental endothelium we propose that insulin is a factor restoring endothelial function in GDM by reversing ERS, hypercholesterolaemia and angiogenesis to a physiological state involving insulin activation of insulin receptor isoforms and adenosine receptors and metabolism in the human placenta from GDM pregnancies. PMID:27065887

  9. Modulation of Glucose Transporter Protein by Dietary Flavonoids in Type 2 Diabetes Mellitus

    PubMed Central

    Hajiaghaalipour, Fatemeh; Khalilpourfarshbafi, Manizheh; Arya, Aditya

    2015-01-01

    Diabetes mellitus (DM) is a metabolic diseases characterized by hyperglycemia due to insufficient or inefficient insulin secretory response. This chronic disease is a global problem and there is a need for greater emphasis on therapeutic strategies in the health system. Phytochemicals such as flavonoids have recently attracted attention as source materials for the development of new antidiabetic drugs or alternative therapy for the management of diabetes and its related complications. The antidiabetic potential of flavonoids are mainly through their modulatory effects on glucose transporter by enhancing GLUT-2 expression in pancreatic β cells and increasing expression and promoting translocation of GLUT-4 via PI3K/AKT, CAP/Cb1/TC10 and AMPK pathways. This review highlights the recent findings on beneficial effects of flavonoids in the management of diabetes with particular emphasis on the investigations that explore the role of these compounds in modulating glucose transporter proteins at cellular and molecular level. PMID:25892959

  10. Synergistic effects between catalase inhibitors and modulators of nitric oxide metabolism on tumor cell apoptosis.

    PubMed

    Scheit, Katrin; Bauer, Georg

    2014-10-01

    Inhibitors of catalase (such as ascorbate, methyldopa, salicylic acid and neutralizing antibodies) synergize with modulators of nitric oxide (NO) metabolism (such as arginine, arginase inhibitor, NO synthase-inducing interferons and NO dioxygenase inhibitors) in the singlet oxygen-mediated inactivation of tumor cell protective catalase. This is followed by reactive oxygen species (ROS)-dependent apoptosis induction. TGF-beta, NADPH oxidase-1, NO synthase, dual oxidase-1 and caspase-9 are characterized as essential catalysts in this process. The FAS receptor and caspase-8 are required for amplification of ROS signaling triggered by individual compounds, but are dispensable when the synergistic effect is established. Our findings explain the antitumor effects of catalase inhibitors and of compounds that target NO metabolism, as well as their synergy. These data may have an impact on epidemiological studies related to secondary plant compounds and open new perspectives for the establishment of novel antitumor drugs and for the improvement of established chemotherapeutics. PMID:25275027

  11. Metabolic Enzymes Enjoying New Partnerships as RNA-Binding Proteins

    PubMed Central

    Castello, Alfredo; Hentze, Matthias W.; Preiss, Thomas

    2015-01-01

    In the past century, few areas of biology advanced as much as our understanding of the pathways of intermediary metabolism. Initially considered unimportant in terms of gene regulation, crucial cellular fate changes, cell differentiation, or malignant transformation are now known to involve ‘metabolic remodeling’ with profound changes in the expression of many metabolic enzyme genes. This review focuses on the recent identification of RNA-binding activity of numerous metabolic enzymes. We discuss possible roles of this unexpected second activity in feedback gene regulation (‘moonlighting’) and/or in the control of enzymatic function. We also consider how metabolism-driven post-translational modifications could regulate enzyme–RNA interactions. Thus, RNA emerges as a new partner of metabolic enzymes with far-reaching possible consequences to be unraveled in the future. PMID:26520658

  12. Murine Gut Microbiota Is Defined by Host Genetics and Modulates Variation of Metabolic Traits

    PubMed Central

    Lu, Lu; Williams, Evan G.; Brewer, Simon; Andreux, Pénélope A.; Bastiaansen, John W. M.; Wang, Xusheng; Kachman, Stephen D.; Auwerx, Johan; Williams, Robert W.; Benson, Andrew K.; Peterson, Daniel A.; Ciobanu, Daniel C.

    2012-01-01

    The gastrointestinal tract harbors a complex and diverse microbiota that has an important role in host metabolism. Microbial diversity is influenced by a combination of environmental and host genetic factors and is associated with several polygenic diseases. In this study we combined next-generation sequencing, genetic mapping, and a set of physiological traits of the BXD mouse population to explore genetic factors that explain differences in gut microbiota and its impact on metabolic traits. Molecular profiling of the gut microbiota revealed important quantitative differences in microbial composition among BXD strains. These differences in gut microbial composition are influenced by host-genetics, which is complex and involves many loci. Linkage analysis defined Quantitative Trait Loci (QTLs) restricted to a particular taxon, branch or that influenced the variation of taxa across phyla. Gene expression within the gastrointestinal tract and sequence analysis of the parental genomes in the QTL regions uncovered candidate genes with potential to alter gut immunological profiles and impact the balance between gut microbial communities. A QTL region on Chr 4 that overlaps several interferon genes modulates the population of Bacteroides, and potentially Bacteroidetes and Firmicutes–the predominant BXD gut phyla. Irak4, a signaling molecule in the Toll-like receptor pathways is a candidate for the QTL on Chr15 that modulates Rikenellaceae, whereas Tgfb3, a cytokine modulating the barrier function of the intestine and tolerance to commensal bacteria, overlaps a QTL on Chr 12 that influence Prevotellaceae. Relationships between gut microflora, morphological and metabolic traits were uncovered, some potentially a result of common genetic sources of variation. PMID:22723961

  13. Modulation of bryostatin 1 muscle toxicity by nifedipine: effects on muscle metabolism and oxygen supply.

    PubMed Central

    Thompson, C. H.; Macaulay, V. M.; O'Byrne, K. J.; Kemp, G. J.; Wilner, S. M.; Talbot, D. C.; Harris, A. L.; Radda, G. K.

    1996-01-01

    Bryostatin 1, an anti-neoplastic agent and protein kinase C activator, has dose-limiting toxicity manifesting as myalgia. Studies in vivo have suggested that this myalgia may be caused by impairment of oxidative metabolism as mitochondrial capacity, muscle reoxygenation and proton washout from muscle are reduced by bryostatin, possibly as a result of vasoconstriction. To investigate these mechanisms further, and to enable use of bryostatin for prolonged periods, the effect of a vasodilator on the established effects of bryostatin on calf metabolism was studied using 31P magnetic resonance spectroscopy and near infrared spectroscopy. Six patients with disseminated melanoma were examined on four occasions: before and 1 week after initiation of long-term nifedipine (10 mg twice daily) treatment and then 4 and 48 h after bryostatin infusion (25 micrograms m(-2)). Nifedipine impaired muscle oxidative metabolism but had no effect on proton efflux or muscle reoxygenation rate. In the presence of nifedipine, two of the effects of bryostatin, impaired reoxygenation rate and reduced proton efflux, were abolished, but the impaired mitochondrial activity remained. These results show that nifedipine counteracted the vasoconstrictive effect of bryostatin 1. However, because nifedipine itself had an unexpected effect on mitochondrial metabolism, it was not possible to assess whether nifedipine modified bryostatin's effect on this variable. There was no additive detrimental effect of bryostatin on mitochondrial metabolism and nifedipine did not reduce the clinical toxicity of bryostatin 1, which cannot therefore be due to vasoconstriction. PMID:8630272

  14. Metabolic Turnover of Synaptic Proteins: Kinetics, Interdependencies and Implications for Synaptic Maintenance

    PubMed Central

    Cohen, Laurie D.; Zuchman, Rina; Sorokina, Oksana; Müller, Anke; Dieterich, Daniela C.; Armstrong, J. Douglas; Ziv, Tamar; Ziv, Noam E.

    2013-01-01

    Chemical synapses contain multitudes of proteins, which in common with all proteins, have finite lifetimes and therefore need to be continuously replaced. Given the huge numbers of synaptic connections typical neurons form, the demand to maintain the protein contents of these connections might be expected to place considerable metabolic demands on each neuron. Moreover, synaptic proteostasis might differ according to distance from global protein synthesis sites, the availability of distributed protein synthesis facilities, trafficking rates and synaptic protein dynamics. To date, the turnover kinetics of synaptic proteins have not been studied or analyzed systematically, and thus metabolic demands or the aforementioned relationships remain largely unknown. In the current study we used dynamic Stable Isotope Labeling with Amino acids in Cell culture (SILAC), mass spectrometry (MS), Fluorescent Non–Canonical Amino acid Tagging (FUNCAT), quantitative immunohistochemistry and bioinformatics to systematically measure the metabolic half-lives of hundreds of synaptic proteins, examine how these depend on their pre/postsynaptic affiliation or their association with particular molecular complexes, and assess the metabolic load of synaptic proteostasis. We found that nearly all synaptic proteins identified here exhibited half-lifetimes in the range of 2–5 days. Unexpectedly, metabolic turnover rates were not significantly different for presynaptic and postsynaptic proteins, or for proteins for which mRNAs are consistently found in dendrites. Some functionally or structurally related proteins exhibited very similar turnover rates, indicating that their biogenesis and degradation might be coupled, a possibility further supported by bioinformatics-based analyses. The relatively low turnover rates measured here (∼0.7% of synaptic protein content per hour) are in good agreement with imaging-based studies of synaptic protein trafficking, yet indicate that the metabolic load

  15. Metabolic turnover of synaptic proteins: kinetics, interdependencies and implications for synaptic maintenance.

    PubMed

    Cohen, Laurie D; Zuchman, Rina; Sorokina, Oksana; Müller, Anke; Dieterich, Daniela C; Armstrong, J Douglas; Ziv, Tamar; Ziv, Noam E

    2013-01-01

    Chemical synapses contain multitudes of proteins, which in common with all proteins, have finite lifetimes and therefore need to be continuously replaced. Given the huge numbers of synaptic connections typical neurons form, the demand to maintain the protein contents of these connections might be expected to place considerable metabolic demands on each neuron. Moreover, synaptic proteostasis might differ according to distance from global protein synthesis sites, the availability of distributed protein synthesis facilities, trafficking rates and synaptic protein dynamics. To date, the turnover kinetics of synaptic proteins have not been studied or analyzed systematically, and thus metabolic demands or the aforementioned relationships remain largely unknown. In the current study we used dynamic Stable Isotope Labeling with Amino acids in Cell culture (SILAC), mass spectrometry (MS), Fluorescent Non-Canonical Amino acid Tagging (FUNCAT), quantitative immunohistochemistry and bioinformatics to systematically measure the metabolic half-lives of hundreds of synaptic proteins, examine how these depend on their pre/postsynaptic affiliation or their association with particular molecular complexes, and assess the metabolic load of synaptic proteostasis. We found that nearly all synaptic proteins identified here exhibited half-lifetimes in the range of 2-5 days. Unexpectedly, metabolic turnover rates were not significantly different for presynaptic and postsynaptic proteins, or for proteins for which mRNAs are consistently found in dendrites. Some functionally or structurally related proteins exhibited very similar turnover rates, indicating that their biogenesis and degradation might be coupled, a possibility further supported by bioinformatics-based analyses. The relatively low turnover rates measured here (∼0.7% of synaptic protein content per hour) are in good agreement with imaging-based studies of synaptic protein trafficking, yet indicate that the metabolic load

  16. DELLA proteins modulate Arabidopsis defences induced in response to caterpillar herbivory

    PubMed Central

    Bede, Jacqueline C.

    2014-01-01

    Upon insect herbivory, many plant species change the direction of metabolic flux from growth into defence. Two key pathways modulating these processes are the gibberellin (GA)/DELLA pathway and the jasmonate pathway. In this study, the effect of caterpillar herbivory on plant-induced responses was compared between wild-type Arabidopsis thaliana (L.) Heynh. and quad-della mutants that have constitutively elevated GA responses. The labial saliva (LS) of caterpillars of the beet armyworm, Spodoptera exigua, is known to influence induced plant defence responses. To determine the role of this herbivore cue in determining metabolic shifts, plants were subject to herbivory by caterpillars with intact or impaired LS secretions. In both wild-type and quad-della plants, a jasmonate burst is an early response to caterpillar herbivory. Negative growth regulator DELLA proteins are required for the LS-mediated suppression of hormone levels. Jasmonate-dependent marker genes are induced in response to herbivory independently of LS, with the exception of AtPDF1.2 that showed LS-dependent expression in the quad-della mutant. Early expression of the salicylic acid (SA)-marker gene, AtPR1, was not affected by herbivory which also reflected SA hormone levels; however, this gene showed LS-dependent expression in the quad-della mutant. DELLA proteins may positively regulate glucosinolate levels and suppress laccase-like multicopper oxidase activity in response to herbivory. The present results show a link between DELLA proteins and early, induced plant defences in response to insect herbivory; in particular, these proteins are necessary for caterpillar LS-associated attenuation of defence hormones. PMID:24399173

  17. The Modulation of the Symbiont/Host Interaction between Wolbachia pipientis and Aedes fluviatilis Embryos by Glycogen Metabolism

    PubMed Central

    da Rocha Fernandes, Mariana; Martins, Renato; Pessoa Costa, Evenilton; Casagrande Pacidônio, Etiene; Araujo de Abreu, Leonardo; da Silva Vaz, Itabajara; Moreira, Luciano A.; da Fonseca, Rodrigo Nunes; Logullo, Carlos

    2014-01-01

    Wolbachia pipientis, a maternally transmitted bacterium that colonizes arthropods, may affect the general aspects of insect physiology, particularly reproduction. Wolbachia is a natural endosymbiont of Aedes fluviatilis, whose effects in embryogenesis and reproduction have not been addressed so far. In this context, we investigated the correlation between glucose metabolism and morphological alterations during A. fluviatilis embryo development in Wolbachia-positive (W+) and Wolbachia-negative (W−) mosquito strains. While both strains do not display significant morphological and larval hatching differences, larger differences were observed in hexokinase activity and glycogen contents during early and mid-stages of embryogenesis, respectively. To investigate if glycogen would be required for parasite-host interaction, we reduced Glycogen Synthase Kinase-3 (GSK-3) levels in adult females and their eggs by RNAi. GSK-3 knock-down leads to embryonic lethality, lower levels of glycogen and total protein and Wolbachia reduction. Therefore, our results suggest that the relationship between A. fluviatilis and Wolbachia may be modulated by glycogen metabolism. PMID:24926801

  18. Effect of SO/sub 2/ on light modulation of plant metabolism. Progress report

    SciTech Connect

    Anderson, L.E.

    1985-01-01

    This progress report briefly notes conclusions of work done on SO/sub 2/ effect on light modulation of plant metabolism. Conclusions include: effect of light activation on kinetic parameters of fructosebisphosphatase - for this enzyme K/sub m/ decreases and V/sub max/ increases as a result of light activation; and the effect of sulfite and arsenite on light activation in 2 Pisum cultivars - the differences in sensitivity to SO/sub 2/ is directly reflected in differences in a thylakoid bound factor (LEM) to SO/sub 2/.

  19. Protein engineering for metabolic engineering: Current and next-generation tools

    SciTech Connect

    Marcheschi, RJ; Gronenberg, LS; Liao, JC

    2013-04-16

    Protein engineering in the context of metabolic engineering is increasingly important to the field of industrial biotechnology. As the demand for biologically produced food, fuels, chemicals, food additives, and pharmaceuticals continues to grow, the ability to design and modify proteins to accomplish new functions will be required to meet the high productivity demands for the metabolism of engineered organisms. We review advances in selecting, modeling, and engineering proteins to improve or alter their activity. Some of the methods have only recently been developed for general use and are just beginning to find greater application in the metabolic engineering community. We also discuss methods of generating random and targeted diversity in proteins to generate mutant libraries for analysis. Recent uses of these techniques to alter cofactor use; produce non-natural amino acids, alcohols, and carboxylic acids; and alter organism phenotypes are presented and discussed as examples of the successful engineering of proteins for metabolic engineering purposes.

  20. Protein engineering for metabolic engineering: current and next-generation tools

    PubMed Central

    Marcheschi, Ryan J.; Gronenberg, Luisa S.; Liao, James C.

    2014-01-01

    Protein engineering in the context of metabolic engineering is increasingly important to the field of industrial biotechnology. As the demand for biologically-produced food, fuels, chemicals, food additives, and pharmaceuticals continues to grow, the ability to design and modify proteins to accomplish new functions will be required to meet the high productivity demands for the metabolism of engineered organisms. This article reviews advances of selecting, modeling, and engineering proteins to improve or alter their activity. Some of the methods have only recently been developed for general use and are just beginning to find greater application in the metabolic engineering community. We also discuss methods of generating random and targeted diversity in proteins to generate mutant libraries for analysis. Recent uses of these techniques to alter cofactor use, produce non-natural amino acids, alcohols, and carboxylic acids, and alter organism phenotypes are presented and discussed as examples of the successful engineering of proteins for metabolic engineering purposes. PMID:23589443

  1. Dietary, Metabolic, and Potentially Environmental Modulation of the Lysine Acetylation Machinery

    PubMed Central

    Kim, Go-Woon; Gocevski, Goran; Wu, Chao-Jung; Yang, Xiang-Jiao

    2010-01-01

    Healthy lifestyles and environment produce a good state of health. A number of scientific studies support the notion that external stimuli regulate an individual's epigenomic profile. Epigenetic changes play a key role in defining gene expression patterns under both normal and pathological conditions. As a major posttranslational modification, lysine (K) acetylation has received much attention, owing largely to its significant effects on chromatin dynamics and other cellular processes across species. Lysine acetyltransferases and deacetylases, two opposing families of enzymes governing K-acetylation, have been intimately linked to cancer and other diseases. These enzymes have been pursued by vigorous efforts for therapeutic development in the past 15 years or so. Interestingly, certain dietary components have been found to modulate acetylation levels in vivo. Here we review dietary, metabolic, and environmental modulators of the K-acetylation machinery and discuss how they may be of potential value in the context of disease prevention. PMID:20976254

  2. Three Peptides from Soy Glycinin Modulate Glucose Metabolism in Human Hepatic HepG2 Cells.

    PubMed

    Lammi, Carmen; Zanoni, Chiara; Arnoldi, Anna

    2015-01-01

    Ile-Ala-Val-Pro-Gly-Glu-Val-Ala (IAVPGEVA), Ile-Ala-Val-Pro-Thr-Gly-Val-Ala (IAVPTGVA) and Leu-Pro-Tyr-Pro (LPYP), three peptides deriving from soy glycinin hydrolysis, are known to regulate cholesterol metabolism in human hepatic HepG2 cells. We have recently demonstrated that the mechanism of action involves the activation of adenosine monophosphate-activated protein kinase (AMPK). This fact suggested a potential activity of the same peptides on glucose metabolism that prompted us to also investigate this aspect in the same cells. After treatment with IAVPGEVA, IAVPTGVA and LPYP, HepG2 cells were analyzed using a combination of molecular techniques, including western blot analysis, glucose uptake experiments and fluorescence microscopy evaluation. The results showed that these peptides are indeed able to enhance the capacity of HepG2 cells to uptake glucose, via glucose transporter 1 GLUT1 and glucose transporter 4 GLUT4 activation, through the stimulation of protein kinase B Akt and adenosine monophosphate-activated protein kinase AMPK pathways, both involved in glucose metabolism. PMID:26580610

  3. Three Peptides from Soy Glycinin Modulate Glucose Metabolism in Human Hepatic HepG2 Cells

    PubMed Central

    Lammi, Carmen; Zanoni, Chiara; Arnoldi, Anna

    2015-01-01

    Ile-Ala-Val-Pro-Gly-Glu-Val-Ala (IAVPGEVA), Ile-Ala-Val-Pro-Thr-Gly-Val-Ala (IAVPTGVA) and Leu-Pro-Tyr-Pro (LPYP), three peptides deriving from soy glycinin hydrolysis, are known to regulate cholesterol metabolism in human hepatic HepG2 cells. We have recently demonstrated that the mechanism of action involves the activation of adenosine monophosphate-activated protein kinase (AMPK). This fact suggested a potential activity of the same peptides on glucose metabolism that prompted us to also investigate this aspect in the same cells. After treatment with IAVPGEVA, IAVPTGVA and LPYP, HepG2 cells were analyzed using a combination of molecular techniques, including western blot analysis, glucose uptake experiments and fluorescence microscopy evaluation. The results showed that these peptides are indeed able to enhance the capacity of HepG2 cells to uptake glucose, via glucose transporter 1 GLUT1 and glucose transporter 4 GLUT4 activation, through the stimulation of protein kinase B Akt and adenosine monophosphate-activated protein kinase AMPK pathways, both involved in glucose metabolism. PMID:26580610

  4. Deep Proteomics of Mouse Skeletal Muscle Enables Quantitation of Protein Isoforms, Metabolic Pathways, and Transcription Factors*

    PubMed Central

    Deshmukh, Atul S.; Murgia, Marta; Nagaraj, Nagarjuna; Treebak, Jonas T.; Cox, Jürgen; Mann, Matthias

    2015-01-01

    Skeletal muscle constitutes 40% of individual body mass and plays vital roles in locomotion and whole-body metabolism. Proteomics of skeletal muscle is challenging because of highly abundant contractile proteins that interfere with detection of regulatory proteins. Using a state-of-the art MS workflow and a strategy to map identifications from the C2C12 cell line model to tissues, we identified a total of 10,218 proteins, including skeletal muscle specific transcription factors like myod1 and myogenin and circadian clock proteins. We obtain absolute abundances for proteins expressed in a muscle cell line and skeletal muscle, which should serve as a valuable resource. Quantitation of protein isoforms of glucose uptake signaling pathways and in glucose and lipid metabolic pathways provides a detailed metabolic map of the cell line compared with tissue. This revealed unexpectedly complex regulation of AMP-activated protein kinase and insulin signaling in muscle tissue at the level of enzyme isoforms. PMID:25616865

  5. Flexible Linker Modulates Glycosaminoglycan Affinity of Decorin Binding Protein A.

    PubMed

    Morgan, Ashli; Sepuru, Krishna Mohan; Feng, Wei; Rajarathnam, Krishna; Wang, Xu

    2015-08-18

    Decorin binding protein A (DBPA) is a glycosaminoglycan (GAG)-binding adhesin found on the surface of the bacterium Borrelia burgdorferi (B. burgdorferi), the causative agent of Lyme disease. DBPA facilitates bacterial adherence to extracellular matrices of human tissues and is crucial during the early stage of the infection process. Interestingly, DBPA from different strains (B31, N40, and PBr) show significant differences in GAG affinities, but the structural basis for the differences is not clear. In this study, we show that GAG affinity of N40 DBPA is modulated in part by flexible segments that control access to the GAG binding site, such that shortening of the linker leads to higher GAG affinity when analyzed using ELISA, gel mobility shift assay, solution NMR, and isothermal titration calorimetry. Our observation that GAG affinity differences among different B. burgdorferi strains can be attributed to a flexible linker domain regulating access to the GAG-binding domain is novel. It also provides a rare example of how neutral amino acids and dynamic segments in GAG binding proteins can have a large influence on GAG affinity and provides insights into why the number of basic amino acids in the GAG-binding site may not be the only factor determining GAG affinity of proteins. PMID:26223367

  6. Capacitance-modulated transistor detects odorant binding protein chiral interactions

    PubMed Central

    Mulla, Mohammad Yusuf; Tuccori, Elena; Magliulo, Maria; Lattanzi, Gianluca; Palazzo, Gerardo; Persaud, Krishna; Torsi, Luisa

    2015-01-01

    Peripheral events in olfaction involve odorant binding proteins (OBPs) whose role in the recognition of different volatile chemicals is yet unclear. Here we report on the sensitive and quantitative measurement of the weak interactions associated with neutral enantiomers differentially binding to OBPs immobilized through a self-assembled monolayer to the gate of an organic bio-electronic transistor. The transduction is remarkably sensitive as the transistor output current is governed by the small capacitance of the protein layer undergoing minute changes as the ligand–protein complex is formed. Accurate determination of the free-energy balances and of the capacitance changes associated with the binding process allows derivation of the free-energy components as well as of the occurrence of conformational events associated with OBP ligand binding. Capacitance-modulated transistors open a new pathway for the study of ultra-weak molecular interactions in surface-bound protein–ligand complexes through an approach that combines bio-chemical and electronic thermodynamic parameters. PMID:25591754

  7. Metabolic phenotype modulation by caloric restriction in a lifelong dog study.

    PubMed

    Richards, Selena E; Wang, Yulan; Claus, Sandrine P; Lawler, Dennis; Kochhar, Sunil; Holmes, Elaine; Nicholson, Jeremy K

    2013-07-01

    profiles enabled an unbiased evaluation of the metabolic markers modulated by a lifetime of caloric restriction and showed differences in the metabolic phenotype of aging due to caloric restriction, which contributes to longevity studies in caloric-restricted animals. Furthermore, OPLS-DA provided a framework such that significant metabolites relating to life extension could be differentiated and integrated with aging processes. PMID:23713866

  8. Age-related changes in retinoic, docosahexaenoic and arachidonic acid modulation in nuclear lipid metabolism.

    PubMed

    Gaveglio, Virginia L; Pascual, Ana C; Giusto, Norma M; Pasquaré, Susana J

    2016-08-15

    The aim of this work was to study how age-related changes could modify several enzymatic activities that regulate lipid mediator levels in nuclei from rat cerebellum and how these changes are modulated by all-trans retinoic acid (RA), docosahexaenoic acid (DHA) and arachidonic acid (AA). The higher phosphatidate phosphohydrolase activity and lower diacylglycerol lipase (DAGL) activity observed in aged animals compared with adults could augment diacylglycerol (DAG) availability in the former. Additionally, monoacylglycerol (MAG) availability could be high due to an increase in lysophosphatidate phosphohydrolase (LPAPase) activity and a decrease in monocylglycerol lipase activity. Interestingly, RA, DHA and AA were observed to modulate these enzymatic activities and this modulation was found to change in aged rats. In adult nuclei, whereas RA led to high DAG and MAG production through inhibition of their hydrolytic enzymes, DHA and AA promoted high MAG production by LPAPase and DAGL stimulation. In contrast, in aged nuclei RA caused high MAG generation whereas DHA and AA diminished it through LPAPase activity modulation. These results demonstrate that aging promotes a different nuclear lipid metabolism as well as a different type of non-genomic regulation by RA, DHA and AA, which could be involved in nuclear signaling events. PMID:27355428

  9. Proteomic analysis of Clostridium thermocellum core metabolism: relative protein expression profiles and growth phase-dependent changes in protein expression

    PubMed Central

    2012-01-01

    Background Clostridium thermocellum produces H2 and ethanol, as well as CO2, acetate, formate, and lactate, directly from cellulosic biomass. It is therefore an attractive model for biofuel production via consolidated bioprocessing. Optimization of end-product yields and titres is crucial for making biofuel production economically feasible. Relative protein expression profiles may provide targets for metabolic engineering, while understanding changes in protein expression and metabolism in response to carbon limitation, pH, and growth phase may aid in reactor optimization. We performed shotgun 2D-HPLC-MS/MS on closed-batch cellobiose-grown exponential phase C. thermocellum cell-free extracts to determine relative protein expression profiles of core metabolic proteins involved carbohydrate utilization, energy conservation, and end-product synthesis. iTRAQ (isobaric tag for relative and absolute quantitation) based protein quantitation was used to determine changes in core metabolic proteins in response to growth phase. Results Relative abundance profiles revealed differential levels of putative enzymes capable of catalyzing parallel pathways. The majority of proteins involved in pyruvate catabolism and end-product synthesis were detected with high abundance, with the exception of aldehyde dehydrogenase, ferredoxin-dependent Ech-type [NiFe]-hydrogenase, and RNF-type NADH:ferredoxin oxidoreductase. Using 4-plex 2D-HPLC-MS/MS, 24% of the 144 core metabolism proteins detected demonstrated moderate changes in expression during transition from exponential to stationary phase. Notably, proteins involved in pyruvate synthesis decreased in stationary phase, whereas proteins involved in glycogen metabolism, pyruvate catabolism, and end-product synthesis increased in stationary phase. Several proteins that may directly dictate end-product synthesis patterns, including pyruvate:ferredoxin oxidoreductases, alcohol dehydrogenases, and a putative bifurcating hydrogenase

  10. Natural Modulators of Amyloid-Beta Precursor Protein Processing

    PubMed Central

    Zhang, Can; Tanzi, Rudolph E.

    2013-01-01

    Alzheimer’s disease (AD) is a devastating neurodegenerative disease and the primary cause of dementia, with no cure currently available. The pathogenesis of AD is believed to be primarily driven by Aβ, the principal component of senile plaques. Aβ is an ~4 kDa peptide generated from the amyloid-β precursor protein (APP) through proteolytic secretases. Natural products, particularly those utilized in traditional Chinese medicine (TCM), have a long history alleviating common clinical disorders, including dementia. However, the cell/molecular pathways mediated by these natural products are largely unknown until recently when the underlying molecular mechanisms of the disorders begin to be elucidated. Here, the mechanisms with which natural products modulate the pathogenesis of AD are discussed, in particular, by focusing on their roles in the processing of APP. PMID:22998566