Substrate specificity and kinetic parameters of GLUT3 in rat cerebellar granule neurons

Maher, Frances A.; Davies-Hill, Theresa; Simpson, Ian A.

doi:10.1042/bj3150827

Cited by 128 publications

(123 citation statements)

References 29 publications

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“…The GLUT3 affinity for CB [K d 440p41 nM (meanpS.E.M. ; n l 6)] is significantly less than that observed for GLUT1 or GLUT4, both of which are of the order of 100 nM, but is consistent with that observed for GLUT3 in neurons [23,32]. (lanes 1-6).…”

Section: Resultssupporting

confidence: 74%

“…sperm and placental epithelium [15][16][17][18][19][20], and is aberrantly expressed in glioblastomas and HIV-infected lymphocytes [21,22]. In neurons, GLUT3 has a high affinity for glucose (K m 2.8 mM) and the highest V max for transport of all the facilitative glucose transporters [23]. It was generally assumed that in all these cells the GLUT3 transporter resides exclusively in the plasma membrane.…”

Section: Introductionmentioning

confidence: 99%

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Thrombin-induced translocation of GLUT3 glucose transporters in human platelets

Sorbara

Davies-Hill

Koehler-Stec

et al. 1997

Biochemical Journal

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Platelets derive most of their energy from anaerobic glycolysis; during activation this requirement rises approx. 3-fold. To accommodate the high glucose flux, platelets express extremely high concentrations (155±18 pmol/mg of membrane protein) of the most active glucose transporter isoform, GLUT3. Thrombin, a potent platelet activator, was found to stimulate 2-deoxyglucose transport activity 3-5-fold within 10 min at 25 °C, with a half-time of 1-2 min. To determine the mechanism underlying the increase in glucose transport activity, an impermeant photolabel, [2-3H]2N-4-(1-azi-2,2,2-trifluoethyl)benzoyl-1,3,-bis-(d-mannose-4-ylozy)-2-propylamine, was used to covalently bind glucose transporters accessible to the extracellular milieu. In response to thrombin, the level of transporter labelling increased 2.7-fold with a half-time of 1-2 min. This suggests a translocation of GLUT3 transporters from an intracellular site to the plasma membrane in a manner analogous to that seen for the translocation of GLUT4 in insulin-stimulated rat adipose cells. To investigate whether a similar signalling pathway was involved in both systems, platelets and adipose cells were exposed to staurosporin and wortmannin, two inhibitors of GLUT4 translocation in adipose cells. Thrombin stimulation of glucose transport activity in platelets was more sensitive to staurosporin inhibition than was insulin-stimulated transport activity in adipose cells, but it was totally insensitive to wortmannin. This indicates that the GLUT3 translocation in platelets is mediated by a protein kinase C not by a phosphatidylinositol 3-kinase mechanism. In support of this contention, the phorbol ester PMA, which specifically activates protein kinase C, fully stimulated glucose transport activity in platelets and was equally sensitive to inhibition by staurosporin. This study provides a cellular mechanism by which platelets enhance their capacity to import glucose to fulfil the increased energy demands associated with activation.

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Section: Resultssupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Thrombin-induced translocation of GLUT3 glucose transporters in human platelets

Sorbara

Davies-Hill

Koehler-Stec

et al. 1997

Biochemical Journal

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“…The most common approaches to achieve this have been either to measure the binding of cytochalasin B, a competitive inhibitor of glucose transport, or to use the Holman reagent, which is a tritiated, impermeant reagent that upon photoactivation covalently binds to all glucose transporter proteins in the correct conformation at the plasma membrane. By use of a combination of such approaches, GLUT3 in rat cerebellar granule neurons was shown by Maher et al to have a significantly greater K cat , 6,500/s, than either GLUT1 expressed in human erythrocytes, 3T3-L1 adipocytes or oocytes, 1,200/s, or GLUT4 in 3T3-L1 adipocytes or oocytes, 1,300/s at 37°C (73,76,77,96,98).…”

Section: Kineticsmentioning

confidence: 99%

The facilitative glucose transporter GLUT3: 20 years of distinction

Simpson

Dwyer

Malide

et al. 2008

American Journal of Physiology-Endocrinology and Metabolism

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395

322

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Glucose metabolism is vital to most mammalian cells, and the passage of glucose across cell membranes is facilitated by a family of integral membrane transporter proteins, the GLUTs. There are currently 14 members of the SLC2 family of GLUTs, several of which have been the focus of this series of reviews. The subject of the present review is GLUT3, which, as implied by its name, was the third glucose transporter to be cloned (Kayano T, Fukumoto H, Eddy RL, Fan YS, Byers MG, Shows TB, Bell GI. J Biol Chem 263: [15245][15246][15247][15248] 1988) and was originally designated as the neuronal GLUT. The overriding question that drove the early work on GLUT3 was why would neurons need a separate glucose transporter isoform? What is it about GLUT3 that specifically suits the needs of the highly metabolic and oxidative neuron with its high glucose demand? More recently, GLUT3 has been studied in other cell types with quite specific requirements for glucose, including sperm, preimplantation embryos, circulating white blood cells, and an array of carcinoma cell lines. The last are sufficiently varied and numerous to warrant a review of their own and will not be discussed here. However, for each of these cases, the same questions apply. Thus, the objective of this review is to discuss the properties and tissue and cellular localization of GLUT3 as well as the features of expression, function, and regulation that distinguish it from the rest of its family and make it uniquely suited as the mediator of glucose delivery to these specific cells.neurons; sperm; preimplantation embryo; white blood cells GLUCOSE METABOLISM IS VITAL to most mammalian cells, and the passage of glucose across cell membranes is facilitated by a family of integral membrane transporter proteins, the GLUTs. There are currently 14 members of the SLC2 family of GLUTs, several of which have been the focus of this series of reviews. The subject of the present review is GLUT3 which, as implied by its name, was the third glucose transporter to be cloned (62) and was originally designated as the neuronal glucose transporter. Together with GLUT1, -2, and -4, it comprises the Class 1 group of transporters (For review see Refs. 15,81,121). With the cloning of GLUT3, it became apparent that the brain did not rely exclusively on GLUT1 and that GLUT3 was highly and specifically expressed by neurons. Thus, GLUT3 became the third facilitative glucose transporter isoform with unique characteristics suited for cell-specific expression and function. GLUT2 is ideally suited for expression in liver and pancreas due to its high K m for glucose; GLUT4 and its translocation from intracellular vesicles to the cell surface facilitates insulin-stimulated glucose uptake in insulin-sensitive cells: muscle and fat. The overriding question that drove the early work in GLUT3 in the brain was: why would neurons need a separate glucose transporter isoform; what is it about GLUT3 that specifically suits the needs of the highly metabolic and oxidative neuron with its high glucose demand?...

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“…When expressed in Xenopus oocytes, GLUT3-mediated glucose transport shows high-affinity glucose transport relative to GLUT1 and GLUT2 (Colville et al, 1993;Rumsey et al, 1997). Glucose transporter3-mediated transport in primary cultures of rat cerebellar granule cell neurons is characterized by high-affinity, highcapacity zero-trans glucose uptake (i.e., into cells that contain zero-glucose) at 241C (Maher et al, 1996). k cat for GLUT3-mediated glucose transport (V max /[GLUT3] cell surface = 880/sec) is significantly greater than GLUT1 k cat at 241C (151/sec; Lowe and Walmsley, 1986).…”

mentioning

confidence: 99%

“…As discussed above, high-affinity CB binding to endothelial cells, astrocytes, and neurons is a good measure of the GLUT content of membranes from these cells because glucose uptake is quantitatively inhibited by CB in each of these systems. Thus, astrocytes contain 5.8 to 7.3 pmol CB binding sites/ mg membrane protein (Keller et al, 1986;Vannucci et al, 1997); endothelial cells contain 400 pmol CB binding sites/mg membrane protein (Simpson et al, 2001); neurons contain 9.5 pmol CB binding sites/ mg membrane protein (Maher et al, 1996). On the basis of CB binding content and glucose transport capacity of rat cerebellar granule neurons, and the identity of their major glucose transport species as GLUT3, Maher et al (1996) conclude that GLUT3 k cat is some eightfold greater than GLUT1 k cat .…”

mentioning

confidence: 99%

Supply and Demand in Cerebral Energy Metabolism: The Role of Nutrient Transporters

Simpson

Carruthers

Vannucci

2007

J Cereb Blood Flow Metab

693

749

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Glucose is the obligate energetic fuel for the mammalian brain, and most studies of cerebral energy metabolism assume that the majority of cerebral glucose utilization fuels neuronal activity via oxidative metabolism, both in the basal and activated state. Glucose transporter (GLUT) proteins deliver glucose from the circulation to the brain: GLUT1 in the microvascular endothelial cells of the blood-brain barrier (BBB) and glia; GLUT3 in neurons. Lactate, the glycolytic product of glucose metabolism, is transported into and out of neural cells by the monocarboxylate transporters (MCT): MCT1 in the BBB and astrocytes and MCT2 in neurons. The proposal of the astrocyte-neuron lactate shuttle hypothesis suggested that astrocytes play the primary role in cerebral glucose utilization and generate lactate for neuronal energetics, especially during activation. Since the identification of the GLUTs and MCTs in brain, much has been learned about their transport properties, that is capacity and affinity for substrate, which must be considered in any model of cerebral glucose uptake and utilization. Using concentrations and kinetic parameters of GLUT1 and -3 in BBB endothelial cells, astrocytes, and neurons, along with the corresponding kinetic properties of the MCTs, we have successfully modeled brain glucose and lactate levels as well as lactate transients in response to neuronal stimulation. Simulations based on these parameters suggest that glucose readily diffuses through the basal lamina and interstitium to neurons, which are primarily responsible for glucose uptake, metabolism, and the generation of the lactate transients observed on neuronal activation. Keywords: glucose and lactate; glucose transporter proteins; mathematical modeling; monocarboxylate transporters; neurons and astrocytes; substrate delivery and metabolism IntroductionThe central dogma of cerebral energy metabolism is that glucose is the obligate energetic fuel of the mammalian brain and the only substrate able to completely sustain neural activity (Siesjo, 1978). Furthermore, it has traditionally been assumed that the majority of cerebral glucose utilization fuels neuronal activity via oxidative metabolism, both in the basal and activated state (Sokoloff et al, 1977). Rates of cerebral blood flow directly relate to measurements of cerebral oxygen consumption, generating the concept of the 'flow-metabolism couple' (Sokoloff, 1976;Sokoloff et al, 1977). The introduction of neuroimaging techniques to study cerebral metabolism revealed an 'uncoupling' between cerebral oxygen consumption, blood flow, and glucose utilization during brain activation (Fox and Raichle, 1986; Fox et al, 1988), with the suggestion of regional stimulation of oxidative glycolysis during neuronal activation. The temporal relationship between the release of lactate and the onset of neuronal activation, the source of the lactate, that is neuronal or glial, and its subsequent diffusion and disposal are all matters of considerable debate. Initial studies by Prichard et al (1991) assu...

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Substrate specificity and kinetic parameters of GLUT3 in rat cerebellar granule neurons

Cited by 128 publications

References 29 publications

Thrombin-induced translocation of GLUT3 glucose transporters in human platelets

Thrombin-induced translocation of GLUT3 glucose transporters in human platelets

The facilitative glucose transporter GLUT3: 20 years of distinction

Supply and Demand in Cerebral Energy Metabolism: The Role of Nutrient Transporters

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