Specific and sensitive ultra-high performance liquid chromatography-quadrupole time of flight-mass spectroscopy (UPLC-QTOF-MS) methods have been developed for the determination of curcuminoids and ...curcumin metabolites in human blood plasma. The UPLC-QTOF-MS method used a binary solvent delivery system and the chromatographic separation was performed on a C-18 (2.1 × 50 mm; 1.7 µm) column. Mass spectra were obtained on a Waters Xevo G2S Q-TOF mass spectrometer. The developed methods to characterize the pharmacokinetics of curcuminoids and curcumin metabolites in human blood plasma after an oral administration of bioavailable curcumin-Cureit™-were validated. It was found that the complete turmeric matrix enhances the concentration of tetrahydrocurcumin (THC), hexahydrocurcumin (HHC), octahydrocurcumin (OHC), curcumin-
-glucuronide (COG) and curcumin-
-sulfate (COS) in the blood plasma once the product is administrated.
Peroxisome proliferator-activated receptor γ coactivator-1 β (PGC-1β) is known to be a transcriptional coactivator for SREBP-1, the master regulator of hepatic lipogenesis. Here, we evaluated the ...role of PGC-1β in the pathogenesis of fructose-induced insulin resistance by using an antisense oligonucletoide (ASO) to knockdown PGC-1β in liver and adipose tissue. PGC-1β ASO improved the metabolic phenotype induced by fructose feeding by reducing expression of SREBP-1 and downstream lipogenic genes in liver. PGC-1β ASO also reversed hepatic insulin resistance induced by fructose in both basal and insulin-stimulated states. Furthermore, PGC-1β ASO increased insulin-stimulated whole-body glucose disposal due to a threefold increase in glucose uptake in white adipose tissue. These data support an important role for PGC-1β in the pathogenesis of fructose-induced insulin resistance and suggest that PGC-1β inhibition may be a therapeutic target for treatment of NAFLD, hypertriglyceridemia, and insulin resistance associated with increased de novo lipogenesis.
Insulin stimulates glucose uptake in fat and muscle by redistributing GLUT4 glucose transporters from intracellular membranes to the cell surface. We previously proposed that, in 3T3-L1 adipocytes, ...TUG retains GLUT4 within unstimulated cells and insulin mobilizes this retained GLUT4 by stimulating its dissociation from TUG. Yet the relative importance of this action in the overall control of glucose uptake remains uncertain. Here we report that transient, small interfering RNA-mediated depletion of TUG causes GLUT4 translocation and enhances glucose uptake in unstimulated 3T3-L1 adipocytes, similar to insulin. Stable TUG depletion or expression of a dominant negative fragment likewise stimulates GLUT4 redistribution and glucose uptake, and insulin causes a 2-fold further increase. Microscopy shows that TUG governs the accumulation of GLUT4 in perinuclear membranes distinct from endosomes and indicates that it is this pool of GLUT4 that is mobilized by TUG disruption. Interestingly, in addition to translocating GLUT4 and enhancing glucose uptake, TUG disruption appears to accelerate the degradation of GLUT4 in lysosomes. Finally, we find that TUG binds directly and specifically to a large intracellular loop in GLUT4. Together, these findings demonstrate that TUG is required to retain GLUT4 intracellularly in 3T3-L1 adipocytes in the absence of insulin and further implicate the insulin-stimulated dissociation of TUG and GLUT4 as an important action by which insulin stimulates glucose uptake.
Rapidly changing concentrations of substrates frequently occur during large-scale microbial cultivations. These changing conditions, caused by large mixing times, result in a heterogeneous population ...distribution. Here, we present a powerful and efficient modeling approach to predict the influence of varying substrate levels on the transcriptional and translational response of the cell. This approach consists of two parts, a single-cell model to describe transcription and translation for an exemplary operon (
operon) and a second part to characterize cell distribution during the experimental setup. Combination of both models enables prediction of transcriptional patterns for the whole population. In summary, the resulting model is not only able to anticipate the experimentally observed short-term and long-term transcriptional response, it further allows envision of altered protein levels. Our model shows that locally induced stress responses propagate throughout the bioreactor, resulting in temporal, and spatial population heterogeneity. Stress induced transcriptional response leads to a new population steady-state shortly after imposing fluctuating substrate conditions. In contrast, the protein levels take more than 10 h to achieve steady-state conditions.
To promote glucose uptake into fat and muscle cells, insulin causes the translocation of GLUT4 glucose transporters from intracellular vesicles to the cell surface. Previous data support a model in ...which TUG traps GLUT4-containing vesicles and tethers them intracellularly in unstimulated cells and in which insulin mobilizes this pool of vesicles by releasing this tether. Here we show that TUG undergoes site-specific endoproteolytic cleavage, which separates a GLUT4-binding, N-terminal region of TUG from a C-terminal region previously suggested to bind an intracellular anchor. Cleavage is accelerated by insulin stimulation in 3T3-L1 adipocytes and is highly dependent upon adipocyte differentiation. The N-terminal TUG cleavage product has properties of a novel 18-kDa ubiquitin-like modifier, which we call TUGUL. The C-terminal product is observed at the expected size of 42 kDa and also as a 54-kDa form that is released from membranes into the cytosol. In transfected cells, intact TUG links GLUT4 to PIST and also binds Golgin-160 through its C-terminal region. PIST is an effector of TC10α, a GTPase previously shown to transmit an insulin signal required for GLUT4 translocation, and we show using RNAi that TC10α is required for TUG proteolytic processing. Finally, we demonstrate that a cleavage-resistant form of TUG does not support highly insulin-responsive GLUT4 translocation or glucose uptake in 3T3-L1 adipocytes. Together with previous results, these data support a model whereby insulin stimulates TUG cleavage to liberate GLUT4 storage vesicles from the Golgi matrix, which promotes GLUT4 translocation to the cell surface and enhances glucose uptake.
Background: GLUT4 glucose transporters are trapped and sequestered intracellularly in adipocytes by TUG.
Results: Insulin stimulates TUG cleavage, which separates regions of TUG that bind GLUT4 and Golgi matrix proteins. Cleavage is required for highly insulin-responsive GLUT4 translocation.
Conclusion: TUG proteolysis liberates GLUT4 trapped at the Golgi matrix.
Significance: Endoproteolytic cleavage is a novel biochemical mechanism for insulin action to regulate glucose uptake.
In adipose and muscle cells, insulin stimulates the exocytic translocation of vesicles containing GLUT4, a glucose transporter, and insulin-regulated aminopeptidase (IRAP), a transmembrane ...aminopeptidase. A substrate of IRAP is vasopressin, which controls water homeostasis. The physiological importance of IRAP translocation to inactivate vasopressin remains uncertain. We previously showed that in skeletal muscle, insulin stimulates proteolytic processing of the GLUT4 retention protein, TUG, to promote GLUT4 translocation and glucose uptake. Here we show that TUG proteolysis also controls IRAP targeting and regulates vasopressin action in vivo. Transgenic mice with constitutive TUG proteolysis in muscle consumed much more water than wild-type control mice. The transgenic mice lost more body weight during water restriction, and the abundance of renal AQP2 water channels was reduced, implying that vasopressin activity is decreased. To compensate for accelerated vasopressin degradation, vasopressin secretion was increased, as assessed by the cosecreted protein copeptin. IRAP abundance was increased in T-tubule fractions of fasting transgenic mice, when compared with controls. Recombinant IRAP bound to TUG, and this interaction was mapped to a short peptide in IRAP that was previously shown to be critical for GLUT4 intracellular retention. In cultured 3T3-L1 adipocytes, IRAP was present in TUG-bound membranes and was released by insulin stimulation. Together with previous results, these data support a model in which TUG controls vesicle translocation by interacting with IRAP as well as GLUT4. Furthermore, the effect of IRAP to reduce vasopressin activity is a physiologically important consequence of vesicle translocation, which is coordinated with the stimulation of glucose uptake.
Background: Insulin stimulates the exocytic translocation of vesicles containing GLUT4 glucose transporters and insulin-regulated aminopeptidase (IRAP).
Results: Insulin acts through TUG proteins to control IRAP targeting, similar to GLUT4; the activity of vasopressin, an IRAP substrate, is reduced in mice with disrupted TUG action in muscle.
Conclusion: TUG regulates vasopressin action.
Significance: Exocytic translocation of vesicles in muscle coordinates vasopressin inactivation with glucose uptake.
The Machine Age of Customer Insightdemonstrates the impact of machine learning and data analytics, combining an academic state-of-the-art overview of machine learning with cases from well-known ...companies. These cases show the opportunities and challenges of the transformation process for business and for customer insights more specifically.
Heat engines transfer high-temperature heat into mechanical and electrical energy using the Clausius Rankine Cycle (CRC). Low temperature applications primarily use the Organic Rankine Cycle, in ...which mainly waste heat, geothermal heat and solar heat are transferred into mechanical energy. The exergy of a low temperature heat source can be transferred into electricity in so-called triangle (or trilateral) cycles. By applying batch processes in heat engines, it is possible to reach an exceptionally high approximation to triangle cycles and thus to build up high exergy-efficient heat engines. In an example case the calculated exergy efficiency is 71% higher compared to a CRC. The proposed process is not limited to specific working media and can therefore be adapted to a wide range of temperatures. The required setup is rather simple and is derived from setups ranging from basic to more and more advanced. The thermodynamic performance of an example plant is derived from T-s-diagrams.
•Batch processes in heat engines lead to a drastically increased electrical output.•The setup contains preheater, superheater, desuperheater.•The examination is carried out using T-s-diagrams and discretisation.•Thermal input, and electrical output are calculated and aggregated.•Energy efficiency and exergy efficiency is calculated, compared, and discussed.
Insulin stimulates glucose uptake in 3T3-L1 adipocytes in part by causing endoproteolytic cleavage of TUG (tether containing a ubiquitin regulatory X (UBX) domain for glucose transporter 4 (GLUT4)). ...Cleavage liberates intracellularly sequestered GLUT4 glucose transporters for translocation to the cell surface. To test the role of this regulation in muscle, we used mice with muscle-specific transgenic expression of a truncated TUG fragment, UBX-Cter. This fragment causes GLUT4 translocation in unstimulated 3T3-L1 adipocytes. We predicted that transgenic mice would have GLUT4 translocation in muscle during fasting. UBX-Cter expression caused depletion of PIST (PDZ domain protein interacting specifically with TC10), which transmits an insulin signal to TUG. Whereas insulin stimulated TUG proteolysis in control muscles, proteolysis was constitutive in transgenic muscles. Fasting transgenic mice had decreased plasma glucose and insulin concentrations compared with controls. Whole-body glucose turnover was increased during fasting but not during hyperinsulinemic clamp studies. In muscles with the greatest UBX-Cter expression, 2-deoxyglucose uptake during fasting was similar to that in control muscles during hyperinsulinemic clamp studies. Fasting transgenic mice had increased muscle glycogen, and GLUT4 targeting to T-tubule fractions was increased 5.7-fold. Whole-body oxygen consumption (VO2), carbon dioxide production (VCO2), and energy expenditure were increased by 12–13%. After 3 weeks on a high fat diet, the decreased fasting plasma glucose in transgenic mice compared with controls was more marked, and increased glucose turnover was not observed; the transgenic mice continued to have an increased metabolic rate. We conclude that insulin stimulates TUG proteolysis to translocate GLUT4 in muscle, that this pathway impacts systemic glucose homeostasis and energy metabolism, and that the effects of activating this pathway are maintained during high fat diet-induced insulin resistance in mice.
Background: Insulin stimulates endoproteolytic cleavage of TUG proteins to promote glucose uptake in cultured adipocytes, but the role of this pathway in muscle is uncharacterized.
Results: Transgenic mice with constitutive and unregulated TUG cleavage in muscle had increased whole-body and muscle-specific glucose uptake during fasting.
Conclusion: Insulin acts through TUG to control glucose uptake in muscle.
Significance: Understanding insulin action will elucidate diabetes pathogenesis.
A Triangle Cycle with a piston engine expansion unit is used to convert low temperature heat into electrical energy. In this process, the isentropic efficiency of the expansion unit is considered to ...be unknown, and a theoretical approach for the calculation of isentropic efficiency is presented. A number of influences are taken into account – dead volume, residual mass, liquid injection performance and wall heat transfer. Various working fluids are investigated in a wide range of temperatures (333K–573K), engine speeds (5 Hz–30 Hz) and stroke volumes (0.1 L–50 L). The isentropic efficiency of water as working fluid is in the range of 0.75–0.88 and drops significantly for high stroke volumes and engine speeds. In general, injection mass has the most impact on isentropic efficiency because it influences dead volume and injection performance. The injection mass increases with vapor density and therefore is significantly influenced by working fluid and temperatures. The Triangle Cycle is compared with Organic Rankine Cycles by using determined isentropic efficiency. The exergetic efficiency of the Triangle Cycle using water is up to 35–70% higher than that of supercritical Organic Rankine Cycles in situations with a heat source temperature of up to 450K.
•The technical realization of a new Triangle Cycle with flash evaporation in a piston engine is described.•A thermodynamic model of the isentropic efficiency with different impacts is presented.•Dead volume, residual mass, injection valve performance and wall heat transfer have been taken into account.•The efficiency of the expansion unit significantly depends on temperature, stroke volume and engine speed.•The Triangle Cycle has a significantly higher efficiency than the Organic Rankine Cycle for heat sources below 450K.
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