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EERE’s internal newsletter, Amped Up!, is a bimonthly publication that highlights news within EERE, as well as some of our external successes, lessons learned, and best practices.
Welcome to the latest issue of our bimonthly newsletter, Amped Up!, highlighting the initiatives, events and technologies in the Office of Energy Efficiency and Renewable Energy that influence change.
Amped Up! is a bimonthly newsletter that highlights the initiatives, events, and technologies in the Office of Energy Efficiency and Renewable Energy that influence change.
Amped Up! is a bimonthly newsletter that highlights the initiatives, events, and technologies in the Office of Energy Efficiency and Renewable Energy that influence change.
Amped Up! is a bimonthly publication that highlights news within EERE, as well as some of our external successes, lessons learned, and best practices.
Amped Up! is a bimonthly publication that highlights news within EERE, as well as some of our external successes, lessons learned, and best practices.
Amped Up! is a bimonthly publication that highlights news within EERE, as well as some of our external successes, lessons learned, and best practices.
Amped Up! is a bimonthly publication that highlights news within EERE, as well as some of our external successes, lessons learned, and best practices.
Amped Up! is a bimonthly publication that highlights news within EERE, as well as some of our external successes, lessons learned, and best practices.
Amped Up! is a bimonthly publication that highlights news within EERE, as well as some of our external successes, lessons learned, and best practices.
Highlights: {yields} Aspirin-induced AMPK phosphorylation was greater in VSMC from SHR than WKY. {yields} Aspirin-induced AMPK phosphorylation inhibited proliferation of VSMC from SHR. {yields} Low basal AMPK phosphorylation in SHR elicits increased VSMC proliferation. {yields} Inhibition of AMPK restored decreased VSMC proliferation by aspirin in SHR. {yields} Aspirin exerts anti-proliferative effect through AMPK activation in VSMC from SHR. -- Abstract: Acetylsalicylic acid (aspirin), used to reduce risk of cardiovascular disease, plays an important role in the regulation of cellular proliferation. However, mechanisms responsible for aspirin-induced growth inhibition are not fully understood. Here, we investigated whether aspirin may exert therapeutic effects via AMP-activated protein kinase (AMPK) activation in vascular smooth muscle cells (VSMC) from wistar kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Aspirin increased AMPK and acetyl-CoA carboxylase phosphorylation in a time- and dose-dependent manner in VSMCs from WKY and SHR, but with greater efficacy in SHR. In SHR, a low basal phosphorylation status of AMPK resulted in increased VSMC proliferation and aspirin-induced AMPK phosphorylation inhibited proliferation of VSMCs. Compound C, an AMPK inhibitor, and AMPK siRNA reduced the aspirin-mediated inhibition of VSMC proliferation, this effect was more pronounced in SHR than in WKY. In VSMCs from SHR, aspirin increased p53 and p21 expression and inhibited the expression of cell cycle associated proteins, such as p-Rb, cyclin D, and cyclin E. These results indicate that in SHR VSMCs aspirin exerts anti-proliferative effects through the induction of AMPK phosphorylation.
Highlights: • Gomisin N activated AMPK/Akt signaling in C2C12 myotubes. • Gomisin N stimulated glucose uptake in C2C12 myotubes. • Gomisin N promoted mitochondria biogenesis and fatty acid oxidation in C2C12 myotubes. • Gomisin N reduced hyperglycemia and improved glucose tolerance in HFD obese mice. Gomisin N (GN) is a lignan derived from Schisandra chinensis. AMP-activated kinase (AMPK) has gained attention as a therapeutic target for the treatment of metabolic syndrome. Previously, we reported that GN activated the AMPK pathway and ameliorated high-fat diet (HFD)-induced hepatic steatosis. In this study, we investigated the anti-diabetic effects of GN in C2C12 myotubes and HFD obese mice. GN enhanced the phosphorylation of AMPK/acetyl-CoA carboxylase (ACC) and Akt. In addition, GN promoted glucose uptake in C2C12 myotubes, which was accompanied by the translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Treatment with compound C, an AMPK inhibitor, suppressed GN-mediated stimulation of glucose uptake. Furthermore, GN increased the expression of mitochondria biogenesis and fatty acid oxidation genes in C2C12 myotubes. In the in vivo study, administration of GN to HFD mice decreased the levels of fasting blood glucose and insulin, and improved glucose tolerance in HFD obese mice. GN administration rescued the decreased phosphorylation of AMPK and Akt and stimulated the expression of mitochondria biogenesis genes in the skeletal muscle of HFD mice. These findings suggested that GN exerted anti-hyperglycemic effects through AMPK activation.
Highlights: • Compound 991 (C991) activates AMPK signaling in osteoblast cells. • C991 attenuates dexamethasone (Dex)-induced osteoblast cell death. • AMPK activation is required for C991-mediated osteoblast protection against Dex. • C991 inhibits Dex-induced oxidative stress in osteoblasts. • Genetic AMPK inhibition reverses C991's anti-oxidant actions in osteoblasts. Dexamethasone (Dex) induces direct cytotoxicity to cultured osteoblasts. The benzimidazole derivative compound 991 (“C991”) is a novel and highly-efficient AMP-activated protein kinase (AMPK) activator. Here, in both MC3T3-E1 osteoblastic cells and primary murine osteoblasts, treatment with C991 activated AMPK signaling, and significantly attenuated Dex-induced apoptotic and non-apoptotic cell death. AMPKα1 knockdown (by shRNA), complete knockout (by CRISPR/Cas9 method) or dominant negative mutation (T172A) not only blocked C991-mediated AMPK activation, but also abolished its pro-survival effect against Dex in osteoblasts. Further studies showed that C991 boosted nicotinamide adenine dinucleotide phosphate (NADPH) activity and induced mRNA expression of NF-E2-related factor 2 (Nrf2)-regulated genes (heme oxygenase-1 and NADPH quinone oxidoreductase 1). Additionally, C991 alleviated Dex-induced reactive oxygen species (ROS) production in osteoblasts. Notably, genetic AMPK inhibition reversed the anti-oxidant actions by C991 in Dex-treated osteoblasts. Together, we conclude that C991 activates AMPK signaling to protect osteoblasts from Dex.
Highlights: • Ogt deletion enhances exercise-dependent glucose utilization in skeletal muscle. • Ogt depletion enhances glucose uptake and oxidation in C2C12 myotubes. • Lack of O-GlcNAcylation increases AMPKα protein expression both in vivo and in vitro. • Ogt deletion in skeletal muscle reverses HFD-induced obesity and insulin resistance. O-GlcNAcylation is a post-translational modification that is characterized by the addition of N-acetylglucosamine (GlcNAc) to proteins by O-GlcNAc transferase (Ogt). The degree of O-GlcNAcylation is thought to be associated with glucotoxicity and diabetic complications, because GlcNAc is produced by a branch of the glycolytic pathway. However, its role in skeletal muscle has not been fully elucidated. In this study, we created skeletal muscle-specific Ogt knockout (Ogt-MKO) mice and analyzed their glucose metabolism. During an intraperitoneal glucose tolerance test, blood glucose was slightly lower in Ogt-MKO mice than in control Ogt-flox mice. High fat diet-induced obesity and insulin resistance were reversed in Ogt-MKO mice. In addition, 12-month-old Ogt-MKO mice had lower adipose and body mass. A single bout of exercise significantly reduced blood glucose in Ogt-MKO mice, probably because of higher AMP-activated protein kinase α (AMPKα) protein expression. Furthermore, intraperitoneal injection of 5-aminoimidazole-4-carboxamide ribonucleotide, an AMPK activator, resulted in a more marked decrease in blood glucose levels in Ogt-MKO mice than in controls. Finally, Ogt knockdown by siRNA in C2C12 myotubes significantly increased protein expression of AMPKα, glucose uptake and oxidation. In conclusion, loss of O-GlcNAcylation facilitates glucose utilization in skeletal muscle, potentially through AMPK activation. The inhibition of O-GlcNAcylation in skeletal muscle may have an anti-diabetic effect, through an enhancement of glucose utilization during exercise.
Highlights: • Effects of fluvastatin in human hepatocytes via SIRT6 activation were investigated. • Fluvastatin plays the role of an SIRT6 activator. • Fluvastatin can be used as a new drug for patients with liver steatosis. • Fluvastatin inhibited lipid synthesis by regulating SREBP1 via LKB1/AMPK pathway. Sirtuins, a family of NAD{sup +}-dependent deacetylase enzymes, have been identified as mammalian homologs of yeast silent information regulator 2 (SIR2). Sirtuin 6 (SIRT6) plays important roles in cell homeostasis, DNA damage repair, cancer suppression, and aging. SIRT6 overexpression improves metabolic diseases, such as hypercholesterolemia, cholesterol-related disease, and type 2 diabetes via AMP-activated protein kinase (AMPK) activation. SIRT6 is abundant in the liver and is a crucial target for patients with liver steatosis. Compounds for drug repositioning were screened to identify potential SIRT6 activators, and fluvastatin, a synthetic inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase that reduces cholesterol synthesis, was identified to activate SIRT6. When HepG2 cells were treated with fluvastatin, the expression of SIRT6 and phosphorylation of sterol regulatory element-binding protein (SREBP)-1 and AMPKα, which is regulated by SIRT6, increased. In this study, we examined the mechanism underlying cholesterol regulation by fluvastatin via SREBP-1 and AMPKα pathway and suggested that fluvastatin is an SIRT6 activator that regulates cholesterol homeostasis and fatty liver disease.
Previous studies have shown that AMP-activated protein kinase (AMPK), a crucial regulator of energy homeostasis, plays important roles in osteoblast differentiation and mineralization. However, little is known about in vivo roles of osteoblastic AMPK in glucose metabolism and bone mass regulation in adult mice. Here, we used the inducible Cre system to control the onset of Ampk disruption after birth by removing doxycycline supplementation. We conditionally inactivated Ampk in osterix (Osx)-expressing cells in 3-week-old Ampk{sup −/−} mice. After 6 months of Ampk inactivation, the Ampk{sup −/−} mice displayed lower serum osteocalcin levels as well as glucose intolerance and insulin resistance, as indicated by glucose tolerance and insulin tolerance tests, respectively, when compared with wild-type mice. After 18 months of Ampk inactivation, micro computed tomography showed significant reductions in trabecular bone volume and cortical bone thickness in the femur of Ampk{sup −/−} mice when compared with wild-type mice. Moreover, bone stiffness was significantly lower in Ampk{sup −/−} mice than in wild-type mice. This is the first study to show that osteoblast AMPK plays an important roles in glucose metabolism and in maintaining trabecular bone volume, cortical thickness, and bone strength in adult mice.
The proton detector (PD) measures 3 MeV proton yield distributions from deuterium-deuterium fusion reactions within the Mega Amp Spherical Tokamak (MAST). The PD’s compact four-channel system of collimated and individually oriented silicon detectors probes different regions of the plasma, detecting protons (with gyro radii large enough to be unconfined) leaving the plasma on curved trajectories during neutral beam injection. From first PD data obtained during plasma operation in 2013, proton production rates (up to several hundred kHz and 1 ms time resolution) during sawtooth events were compared to the corresponding MAST neutron camera data. Fitted proton emission profiles in the poloidal plane demonstrate the capabilities of this new system.
A new coherence imaging Doppler spectroscopy diagnostic has been deployed on the UK’s Mega Amp Spherical Tokamak for scrape-off-layer and divertor impurity flow measurements. The system has successfully obtained 2D images of C III, C II, and He II line-of-sight flows, in both the lower divertor and main scrape-off-layer. Flow imaging has been obtained at frame rates up to 1 kHz, with flow resolution of around 1 km/s and spatial resolution better than 1 cm, over a 40° field of view. C III data have been tomographically inverted to obtain poloidal profiles of the parallel impurity flow in the divertor under various conditions. In this paper we present the details of the instrument design, operation, calibration, and data analysis as well as a selection of flow imaging results which demonstrate the diagnostic's capabilities.