Visualizing Sweetness: Increasingly Diverse Applications for Fluorescent-Tagged Glucose Bioprobes and Their Recent Structural Modifications

Kim, Woong Hee; Lee, Jinho; Jung, Da Woon; Williams, Darren R.

doi:10.3390/s120405005

Cited by 79 publications

(90 citation statements)

References 89 publications

(118 reference statements)

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“…Because endothelial cells and astrocytes are the key cell constituents of the BBB involved in blood glucose uptake, we analyzed the effect of I+I on glucose capture by these two types of cells using the fluorescent glucose analog 6-NBDG (25). Whereas neither insulin nor IGF-I modulated glucose uptake in these cells, the combined addition of I+I stimulated it in astrocytes but not in endothelial cells (Fig.…”

Section: I+i Cooperate In Glucose Uptake By Astrocytesmentioning

confidence: 99%

Insulin Regulates Astrocytic Glucose Handling Through Cooperation With IGF-I

et al. 2016

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Brain activity requires a flux of glucose to active regions to sustain increased metabolic demands. Insulin, the main regulator of glucose handling in the body, has been traditionally considered not to intervene in this process. However, we now report that insulin modulates brain glucose metabolism by acting on astrocytes in concert with IGF-I. The cooperation of insulin and IGF-I is needed to recover neuronal activity after hypoglycemia. Analysis of underlying mechanisms show that the combined action of IGF-I and insulin synergistically stimulates a mitogen-activated protein kinase/protein kinase D pathway resulting in translocation of GLUT1 to the cell membrane through multiple protein-protein interactions involving the scaffolding protein GAIP-interacting protein C terminus and the GTPase RAC1. Our observations identify insulin-like peptides as physiological modulators of brain glucose handling, providing further support to consider the brain as a target organ in diabetes.

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Section: I+i Cooperate In Glucose Uptake By Astrocytesmentioning

confidence: 99%

Insulin Regulates Astrocytic Glucose Handling Through Cooperation With IGF-I

et al. 2016

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“…Fluorescence optical imaging, confocal, as well as two-photon microscopy, achieve subcellular resolution and have made important contributions to glial research. Metabolism may also be investigated at cellular resolution with fluorescent glucose analogs, such as 6-NBDG and 2-NBDG, which probe glucose transport and consumption (Kim et al 2012). Although these large molecules are transported and metabolized much more slowly than glucose, they still serve as tracers for studies in vitro and in vivo (Loaiza et al 2003;Rouach et al 2008;Barros et al 2009a;Chuquet et al 2010).…”

Section: Measuring Metabolism Toward Single-cell Readoutsmentioning

confidence: 99%

The Astrocyte: Powerhouse and Recycling Center

Weber

Barros

2015

Cold Spring Harb Perspect Biol

153

121

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Brain metabolism is characterized by fuel monodependence, high-energy expenditure, autonomy from the rest of body, local recycling, and marked division of labor between cell types. Although neurons spend most of the brain's energy on signaling, astrocytes bear the brunt of the metabolic load, controlling the composition of the interstitial fluid, supplying neurons with energy substrates and precursors for biosynthesis, and recycling neurotransmitters, oxidized scavengers, and other waste products. Outstanding questions in this field are the role of oligodendrocytes, the metabolic behavior of the different subtypes of astrocytes during development and disease, and the emerging notion that metabolism may participate directly in information processing. T he energy requirements of the central nervous system (CNS) are very high compared with those of other organs. Although the brain accounts for merely 2% of body weight, it receives 15% of cardiac output, and uses 20% of the oxygen and 25% of the glucose of the total body turnover (Magistretti 2008). A special microarchitecture has evolved to support this extreme need, in which glial cells play a central role (Fig. 1). The microvasculature consists of a complex and dense network of highly interconnected blood vessels (Weber et al. 2008;Blinder et al. 2013) to ensure adequate delivery of oxygen and glucose. Although oxygen diffuses freely into the parenchyma, glucose and other hydrophilic energy substrates are translocated across membranes via specific transporter proteins (Fig. 1). The astrocyte is a polarized cell. One set of astrocytic processes ensheaths the vasculature and a second set reaches toward the synapse, the site of highest energy demand (Harris et al. 2012). Much of the ATP produced in the brain is spent by neurons on the recovery of ion gradients challenged by postsynaptic potentials, with a smaller investment in action potentials and neurotransmitter recycling (Harris et al. 2012). Astrocytes consume considerable energy for their own needs and the cycling of metabolically relevant substances for neurons. These metabolic processes in astrocytes and neurons are the basis for brain mapping using functional magnetic resonance imaging and positron emission tomography (PET)-methods that capture local metabolism either directly or indirectly via hemodynamic changes (Magistretti 2008;Belanger et al. 2011a). Levels of energy consumption in the whole brain are almost constant. However, individual neurons can increase their consumption dramatically. For example, a striatal neuron may Overview of astrocytic metabolism. (Inset) Astrocytes (green) reside between blood vessels (red) and neurons (yellow). Neurons and oligodendrocytes (blue) are not in direct contact with vessels. Astrocytes form metabolic domains and are coupled by gap junctions, through which they exchange metabolites and ions. Energy: The main energy substrate of the brain is glucose (glc), which crosses the endothelium and enters astrocytes via the glucose transporter GLUT1. Glucose is converted b...

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“…2-NBDG is preferentially transported into cells via glucose transporters (Barros et al 2009;Kim et al 2012). However, whether the fluorescent glucose analog is handled differently by reactive astrocytes exposed to OGD is not known.…”

Section: Resultsmentioning

confidence: 97%

“…The amount of transported 2-NBDG, measured in cells after incubation for 1 h and normalized to the amount of DNA (n=3). *p<0.05, **p<0.01, and ***p<0.0,05 compared to control cell types, including epithelial cells, erythrocytes, tumor cells, astrocytes, and neurons, shows that 2-NBDG is transported via the glucose transporter and that 2-NBDG is phosphorylated intracellularly by hexokinase (Kim et al 2012).…”

Section: Discussionmentioning

confidence: 96%

2-NBDG as a Marker for Detecting Glucose Uptake in Reactive Astrocytes Exposed to Oxygen-Glucose Deprivation In Vitro

Yan

Zhang

2014

J Mol Neurosci

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Glucose is a necessary source of energy for sustaining cell activities and homeostasis in the brain. Enhanced glucose uptake protects cells during energy depletion including brain ischemia. Astrocytes enhance their glucose uptake during ischemia to supply substrates to neurons and thus support neuronal survival. Radiolabeled substrates are commonly used for in vitro measurement of glucose uptake in astrocytes. Here we optimized a method to measure glucose uptake by astrocytes during oxygen-glucose deprivation (OGD) using the fluorescent substrate 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG). Uptake buffers for 2-NBDG were the same as for (14)C-labeled α-methyl-D-glucopyranoside. Cell lysis buffer was optimized for observing the fluorescence of 2-NBDG, and Hoechst 33258 DNA staining was used for normalization of the 2-NBDG concentration. Uptake was performed on cultures of primary astrocytes by incubating the cells at 37 °C in buffer containing 25-200 μM 2-NBDG. Flow cytometry was performed to visualize uptake in intact cells, and a fluorescence microplate reader was used to measure the intracellular concentration of 2-NBDG in cell homogenates. 2-NBDG uptake was concentration dependent in astrocytes that were exposed or not exposed to OGD. OGD significantly increased 2-NBDG uptake by about 1.2 to 2.5 times in astrocytes compared to control cells. These results show that 2-NBDG can be used to detect glucose transport in astrocytes exposed to OGD.

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Visualizing Sweetness: Increasingly Diverse Applications for Fluorescent-Tagged Glucose Bioprobes and Their Recent Structural Modifications

Cited by 79 publications

References 89 publications

Insulin Regulates Astrocytic Glucose Handling Through Cooperation With IGF-I

Insulin Regulates Astrocytic Glucose Handling Through Cooperation With IGF-I

The Astrocyte: Powerhouse and Recycling Center

2-NBDG as a Marker for Detecting Glucose Uptake in Reactive Astrocytes Exposed to Oxygen-Glucose Deprivation In Vitro

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