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Metformin reduces liver glucose production by inhibition of fructose-1-6-bisphosphatase.
Hunter RW, Hughey CC, Lantier L, Sundelin EI, Peggie M, Zeqiraj E, Sicheri F, Jessen N, Wasserman DH, Sakamoto K
(2018) Nat Med 24: 1395-1406
MeSH Terms: Adenosine Monophosphate, Aminoimidazole Carboxamide, Animals, Base Sequence, Chickens, Disease Models, Animal, Fructose-Bisphosphatase, Glucose, Glucose Intolerance, Homeostasis, Humans, Hypoglycemia, Liver, Metformin, Mice, Inbred C57BL, Mutation, Obesity, Prodrugs, Ribonucleotides
Show Abstract · Added March 26, 2019
Metformin is a first-line drug for the treatment of individuals with type 2 diabetes, yet its precise mechanism of action remains unclear. Metformin exerts its antihyperglycemic action primarily through lowering hepatic glucose production (HGP). This suppression is thought to be mediated through inhibition of mitochondrial respiratory complex I, and thus elevation of 5'-adenosine monophosphate (AMP) levels and the activation of AMP-activated protein kinase (AMPK), though this proposition has been challenged given results in mice lacking hepatic AMPK. Here we report that the AMP-inhibited enzyme fructose-1,6-bisphosphatase-1 (FBP1), a rate-controlling enzyme in gluconeogenesis, functions as a major contributor to the therapeutic action of metformin. We identified a point mutation in FBP1 that renders it insensitive to AMP while sparing regulation by fructose-2,6-bisphosphate (F-2,6-P), and knock-in (KI) of this mutant in mice significantly reduces their response to metformin treatment. We observe this during a metformin tolerance test and in a metformin-euglycemic clamp that we have developed. The antihyperglycemic effect of metformin in high-fat diet-fed diabetic FBP1-KI mice was also significantly blunted compared to wild-type controls. Collectively, we show a new mechanism of action for metformin and provide further evidence that molecular targeting of FBP1 can have antihyperglycemic effects.
1 Communities
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19 MeSH Terms
The TLR4 Agonist Monophosphoryl Lipid A Drives Broad Resistance to Infection via Dynamic Reprogramming of Macrophage Metabolism.
Fensterheim BA, Young JD, Luan L, Kleinbard RR, Stothers CL, Patil NK, McAtee-Pereira AG, Guo Y, Trenary I, Hernandez A, Fults JB, Williams DL, Sherwood ER, Bohannon JK
(2018) J Immunol 200: 3777-3789
MeSH Terms: Adenosine Triphosphate, Animals, Candida albicans, Candidiasis, Glycolysis, Lipid A, Macrophages, Male, Mice, Mice, Inbred C57BL, Myeloid Differentiation Factor 88, Signal Transduction, Staphylococcal Infections, Staphylococcus aureus, TOR Serine-Threonine Kinases, Toll-Like Receptor 4
Show Abstract · Added March 28, 2019
Monophosphoryl lipid A (MPLA) is a clinically used TLR4 agonist that has been found to drive nonspecific resistance to infection for up to 2 wk. However, the molecular mechanisms conferring protection are not well understood. In this study, we found that MPLA prompts resistance to infection, in part, by inducing a sustained and dynamic metabolic program in macrophages that supports improved pathogen clearance. Mice treated with MPLA had enhanced resistance to infection with and that was associated with augmented microbial clearance and organ protection. Tissue macrophages, which exhibited augmented phagocytosis and respiratory burst after MPLA treatment, were required for the beneficial effects of MPLA. Further analysis of the macrophage phenotype revealed that early TLR4-driven aerobic glycolysis was later coupled with mitochondrial biogenesis, enhanced malate shuttling, and increased mitochondrial ATP production. This metabolic program was initiated by overlapping and redundant contributions of MyD88- and TRIF-dependent signaling pathways as well as downstream mTOR activation. Blockade of mTOR signaling inhibited the development of the metabolic and functional macrophage phenotype and ablated MPLA-induced resistance to infection in vivo. Our findings reveal that MPLA drives macrophage metabolic reprogramming that evolves over a period of days to support a macrophage phenotype highly effective at mediating microbe clearance and that this results in nonspecific resistance to infection.
Copyright © 2018 by The American Association of Immunologists, Inc.
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16 MeSH Terms
Regional differences in brain glucose metabolism determined by imaging mass spectrometry.
Kleinridders A, Ferris HA, Reyzer ML, Rath M, Soto M, Manier ML, Spraggins J, Yang Z, Stanton RC, Caprioli RM, Kahn CR
(2018) Mol Metab 12: 113-121
MeSH Terms: Adenosine Triphosphate, Animals, Basal Metabolism, Brain, Fasting, Glucose, Glycolysis, Male, Mass Spectrometry, Mice, Mice, Inbred C57BL, Organ Specificity, Pentose Phosphate Pathway
Show Abstract · Added March 26, 2019
OBJECTIVE - Glucose is the major energy substrate of the brain and crucial for normal brain function. In diabetes, the brain is subject to episodes of hypo- and hyperglycemia resulting in acute outcomes ranging from confusion to seizures, while chronic metabolic dysregulation puts patients at increased risk for depression and Alzheimer's disease. In the present study, we aimed to determine how glucose is metabolized in different regions of the brain using imaging mass spectrometry (IMS).
METHODS - To examine the relative abundance of glucose and other metabolites in the brain, mouse brain sections were subjected to imaging mass spectrometry at a resolution of 100 μm. This was correlated with immunohistochemistry, qPCR, western blotting and enzyme assays of dissected brain regions to determine the relative contributions of the glycolytic and pentose phosphate pathways to regional glucose metabolism.
RESULTS - In brain, there are significant regional differences in glucose metabolism, with low levels of hexose bisphosphate (a glycolytic intermediate) and high levels of the pentose phosphate pathway (PPP) enzyme glucose-6-phosphate dehydrogenase (G6PD) and PPP metabolite hexose phosphate in thalamus compared to cortex. The ratio of ATP to ADP is significantly higher in white matter tracts, such as corpus callosum, compared to less myelinated areas. While the brain is able to maintain normal ratios of hexose phosphate, hexose bisphosphate, ATP, and ADP during fasting, fasting causes a large increase in cortical and hippocampal lactate.
CONCLUSION - These data demonstrate the importance of direct measurement of metabolic intermediates to determine regional differences in brain glucose metabolism and illustrate the strength of imaging mass spectrometry for investigating the impact of changing metabolic states on brain function at a regional level with high resolution.
Copyright © 2018 The Authors. Published by Elsevier GmbH.. All rights reserved.
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13 MeSH Terms
Pyruvate induces torpor in obese mice.
Soto M, Orliaguet L, Reyzer ML, Manier ML, Caprioli RM, Kahn CR
(2018) Proc Natl Acad Sci U S A 115: 810-815
MeSH Terms: Adenosine, Adipose Tissue, Brown, Animals, Brain, Insulin Resistance, Male, Mice, Inbred C57BL, Mice, Obese, Obesity, Pyruvic Acid, Torpor, Uncoupling Protein 1
Show Abstract · Added March 22, 2018
Mice subjected to cold or caloric deprivation can reduce body temperature and metabolic rate and enter a state of torpor. Here we show that administration of pyruvate, an energy-rich metabolic intermediate, can induce torpor in mice with diet-induced or genetic obesity. This is associated with marked hypothermia, decreased activity, and decreased metabolic rate. The drop in body temperature correlates with the degree of obesity and is blunted by housing mice at thermoneutrality. Induction of torpor by pyruvate in obese mice relies on adenosine signaling and is accompanied by changes in brain levels of hexose bisphosphate and GABA as detected by mass spectroscopy-based imaging. Pyruvate does not induce torpor in lean mice but results in the activation of brown adipose tissue (BAT) with an increase in the level of uncoupling protein-1 (UCP1). Denervation of BAT in lean mice blocks this increase in UCP1 and allows the pyruvate-induced torpor phenotype. Thus, pyruvate administration induces torpor in obese mice by pathways involving adenosine and GABA signaling and a failure of normal activation of BAT.
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12 MeSH Terms
Programmable base editing of A•T to G•C in genomic DNA without DNA cleavage.
Gaudelli NM, Komor AC, Rees HA, Packer MS, Badran AH, Bryson DI, Liu DR
(2017) Nature 551: 464-471
MeSH Terms: Adenosine Deaminase, Base Pairing, CRISPR-Associated Proteins, Cell Line, Tumor, DNA, DNA Cleavage, Gene Editing, Genome, Human, HEK293 Cells, Humans, Models, Molecular, Polymorphism, Single Nucleotide
Show Abstract · Added March 13, 2018
The spontaneous deamination of cytosine is a major source of transitions from C•G to T•A base pairs, which account for half of known pathogenic point mutations in humans. The ability to efficiently convert targeted A•T base pairs to G•C could therefore advance the study and treatment of genetic diseases. The deamination of adenine yields inosine, which is treated as guanine by polymerases, but no enzymes are known to deaminate adenine in DNA. Here we describe adenine base editors (ABEs) that mediate the conversion of A•T to G•C in genomic DNA. We evolved a transfer RNA adenosine deaminase to operate on DNA when fused to a catalytically impaired CRISPR-Cas9 mutant. Extensive directed evolution and protein engineering resulted in seventh-generation ABEs that convert targeted A•T base pairs efficiently to G•C (approximately 50% efficiency in human cells) with high product purity (typically at least 99.9%) and low rates of indels (typically no more than 0.1%). ABEs introduce point mutations more efficiently and cleanly, and with less off-target genome modification, than a current Cas9 nuclease-based method, and can install disease-correcting or disease-suppressing mutations in human cells. Together with previous base editors, ABEs enable the direct, programmable introduction of all four transition mutations without double-stranded DNA cleavage.
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12 MeSH Terms
Regulation of ATP utilization during metastatic cell migration by collagen architecture.
Zanotelli MR, Goldblatt ZE, Miller JP, Bordeleau F, Li J, VanderBurgh JA, Lampi MC, King MR, Reinhart-King CA
(2018) Mol Biol Cell 29: 1-9
MeSH Terms: Adenosine Diphosphate, Adenosine Triphosphate, Animals, Breast Neoplasms, Cell Line, Tumor, Cell Movement, Collagen, Extracellular Matrix, Female, Glucose, HEK293 Cells, Humans, Intracellular Space, Neoplasm Metastasis, Rats, Serum
Show Abstract · Added April 10, 2019
Cell migration in a three-dimensional matrix requires that cells either remodel the surrounding matrix fibers and/or squeeze between the fibers to move. Matrix degradation, matrix remodeling, and changes in cell shape each require cells to expend energy. While significant research has been performed to understand the cellular and molecular mechanisms guiding metastatic migration, less is known about cellular energy regulation and utilization during three-dimensional cancer cell migration. Here we introduce the use of the genetically encoded fluorescent biomarkers, PercevalHR and pHRed, to quantitatively assess ATP, ADP, and pH levels in MDA-MB-231 metastatic cancer cells as a function of the local collagen microenvironment. We find that the use of the probe is an effective tool for exploring the thermodynamics of cancer cell migration and invasion. Specifically, we find that the ATP:ADP ratio increases in cells in denser matrices, where migration is impaired, and it decreases in cells in aligned collagen matrices, where migration is facilitated. When migration is pharmacologically inhibited, the ATP:ADP ratio decreases. Together, our data indicate that matrix architecture alters cellular energetics and that intracellular ATP:ADP ratio is related to the ability of cancer cells to effectively migrate.
© 2018 Zanotelli, Goldblatt, Miller, et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).
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MeSH Terms
Using two-site binding models to analyze microscale thermophoresis data.
Tso SC, Chen Q, Vishnivetskiy SA, Gurevich VV, Iverson TM, Brautigam CA
(2018) Anal Biochem 540-541: 64-75
MeSH Terms: Adenosine Monophosphate, Algorithms, Animals, Aptamers, Nucleotide, Binding Sites, Cattle, Kinetics, Models, Molecular, Monte Carlo Method, Mutagenesis, Site-Directed, Phytic Acid, Protein Binding, Recombinant Proteins, beta-Arrestin 2
Show Abstract · Added March 14, 2018
The emergence of microscale thermophoresis (MST) as a technique for determining the dissociation constants for bimolecular interactions has enabled these quantities to be measured in systems that were previously difficult or impracticable. However, most models for analyses of these data featured the assumption of a simple 1:1 binding interaction. The only model widely used for multiple binding sites was the Hill equation. Here, we describe two new MST analytic models that assume a 1:2 binding scheme: the first features two microscopic binding constants (K(1) and K(2)), while the other assumes symmetry in the bivalent molecule, culminating in a model with a single macroscopic dissociation constant (K) and a single factor (α) that accounts for apparent cooperativity in the binding. We also discuss the general applicability of the Hill equation for MST data. The performances of the algorithms on both real and simulated data are assessed, and implementation of the algorithms in the MST analysis program PALMIST is discussed.
Copyright © 2017 Elsevier Inc. All rights reserved.
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14 MeSH Terms
Dynamic landscape and regulation of RNA editing in mammals.
Tan MH, Li Q, Shanmugam R, Piskol R, Kohler J, Young AN, Liu KI, Zhang R, Ramaswami G, Ariyoshi K, Gupte A, Keegan LP, George CX, Ramu A, Huang N, Pollina EA, Leeman DS, Rustighi A, Goh YPS, GTEx Consortium, Laboratory, Data Analysis &Coordinating Center (LDACC)—Analysis Working Group, Statistical Methods groups—Analysis Working Group, Enhancing GTEx (eGTEx) groups, NIH Common Fund, NIH/NCI, NIH/NHGRI, NIH/NIMH, NIH/NIDA, Biospecimen Collection Source Site—NDRI, Biospecimen Collection Source Site—RPCI, Biospecimen Core Resource—VARI, Brain Bank Repository—University of Miami Brain Endowment Bank, Leidos Biomedical—Project Management, ELSI Study, Genome Browser Data Integration &Visualization—EBI, Genome Browser Data Integration &Visualization—UCSC Genomics Institute, University of California Santa Cruz, Chawla A, Del Sal G, Peltz G, Brunet A, Conrad DF, Samuel CE, O'Connell MA, Walkley CR, Nishikura K, Li JB
(2017) Nature 550: 249-254
MeSH Terms: Adenosine Deaminase, Animals, Female, Genotype, HEK293 Cells, Humans, Male, Mice, Muscles, Nuclear Proteins, Organ Specificity, Primates, Proteolysis, RNA Editing, RNA-Binding Proteins, Spatio-Temporal Analysis, Species Specificity, Transcriptome
Show Abstract · Added October 27, 2017
Adenosine-to-inosine (A-to-I) RNA editing is a conserved post-transcriptional mechanism mediated by ADAR enzymes that diversifies the transcriptome by altering selected nucleotides in RNA molecules. Although many editing sites have recently been discovered, the extent to which most sites are edited and how the editing is regulated in different biological contexts are not fully understood. Here we report dynamic spatiotemporal patterns and new regulators of RNA editing, discovered through an extensive profiling of A-to-I RNA editing in 8,551 human samples (representing 53 body sites from 552 individuals) from the Genotype-Tissue Expression (GTEx) project and in hundreds of other primate and mouse samples. We show that editing levels in non-repetitive coding regions vary more between tissues than editing levels in repetitive regions. Globally, ADAR1 is the primary editor of repetitive sites and ADAR2 is the primary editor of non-repetitive coding sites, whereas the catalytically inactive ADAR3 predominantly acts as an inhibitor of editing. Cross-species analysis of RNA editing in several tissues revealed that species, rather than tissue type, is the primary determinant of editing levels, suggesting stronger cis-directed regulation of RNA editing for most sites, although the small set of conserved coding sites is under stronger trans-regulation. In addition, we curated an extensive set of ADAR1 and ADAR2 targets and showed that many editing sites display distinct tissue-specific regulation by the ADAR enzymes in vivo. Further analysis of the GTEx data revealed several potential regulators of editing, such as AIMP2, which reduces editing in muscles by enhancing the degradation of the ADAR proteins. Collectively, our work provides insights into the complex cis- and trans-regulation of A-to-I editing.
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18 MeSH Terms
Quantitative Structure-Activity Relationship Modeling of Kinase Selectivity Profiles.
Kothiwale S, Borza C, Pozzi A, Meiler J
(2017) Molecules 22:
MeSH Terms: Adenosine Triphosphate, Area Under Curve, Binding Sites, Databases, Pharmaceutical, Drug Discovery, Models, Molecular, Neural Networks (Computer), Protein Binding, Protein Conformation, Protein Kinase Inhibitors, Protein-Tyrosine Kinases, Quantitative Structure-Activity Relationship, ROC Curve, Software
Show Abstract · Added November 2, 2017
The discovery of selective inhibitors of biological target proteins is the primary goal of many drug discovery campaigns. However, this goal has proven elusive, especially for inhibitors targeting the well-conserved orthosteric adenosine triphosphate (ATP) binding pocket of kinase enzymes. The human kinome is large and it is rather difficult to profile early lead compounds against around 500 targets to gain an upfront knowledge on selectivity. Further, selectivity can change drastically during derivatization of an initial lead compound. Here, we have introduced a computational model to support the profiling of compounds early in the drug discovery pipeline. On the basis of the extensive profiled activity of 70 kinase inhibitors against 379 kinases, including 81 tyrosine kinases, we developed a quantitative structure-activity relation (QSAR) model using artificial neural networks, to predict the activity of these kinase inhibitors against the panel of 379 kinases. The model's performance in predicting activity ranges from 0.6 to 0.8 depending on the kinase, from the area under the curve (AUC) of the receiver operating characteristics (ROC). The profiler is available online at http://www.meilerlab.org/index.php/servers/show?s_id=23.
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14 MeSH Terms
Mouse pancreatic islet macrophages use locally released ATP to monitor beta cell activity.
Weitz JR, Makhmutova M, Almaça J, Stertmann J, Aamodt K, Brissova M, Speier S, Rodriguez-Diaz R, Caicedo A
(2018) Diabetologia 61: 182-192
MeSH Terms: Adenosine Triphosphate, Animals, Insulin, Insulin-Secreting Cells, Islets of Langerhans, Macrophages, Mice, Pancreas
Show Abstract · Added March 21, 2018
AIMS/HYPOTHESIS - Tissue-resident macrophages sense the microenvironment and respond by producing signals that act locally to maintain a stable tissue state. It is now known that pancreatic islets contain their own unique resident macrophages, which have been shown to promote proliferation of the insulin-secreting beta cell. However, it is unclear how beta cells communicate with islet-resident macrophages. Here we hypothesised that islet macrophages sense changes in islet activity by detecting signals derived from beta cells.
METHODS - To investigate how islet-resident macrophages respond to cues from the microenvironment, we generated mice expressing a genetically encoded Ca indicator in myeloid cells. We produced living pancreatic slices from these mice and used them to monitor macrophage responses to stimulation of acinar, neural and endocrine cells.
RESULTS - Islet-resident macrophages expressed functional purinergic receptors, making them exquisite sensors of interstitial ATP levels. Indeed, islet-resident macrophages responded selectively to ATP released locally from beta cells that were physiologically activated with high levels of glucose. Because ATP is co-released with insulin and is exclusively secreted by beta cells, the activation of purinergic receptors on resident macrophages facilitates their awareness of beta cell secretory activity.
CONCLUSIONS/INTERPRETATION - Our results indicate that islet macrophages detect ATP as a proxy signal for the activation state of beta cells. Sensing beta cell activity may allow macrophages to adjust the secretion of factors to promote a stable islet composition and size.
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8 MeSH Terms