Kinetic analysis of the liver-type (GLUT2) and brain-type (GLUT3) glucose transporters in <i>Xenopus</i> oocytes: substrate specificities and effects of transport inhibitors

Colville, Caroline A.; Seatter, Michael J.; Jess, Thomas J.; Gould, Gwyn W.; Thomas, Helen

doi:10.1042/bj2900701

Cited by 155 publications

(137 citation statements)

References 28 publications

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“…A mea sured Km of 0.31 mM in NCB20 cells (Fig. 4) is lower than would be expected for a transport limited process, which should have had an apparent Km 10-20-fold greater, given a Km of GLUTl and GLUn of 4-10 mM (Keller et a!., 1989 ;Gould et a!., 1991;Colville et a!., 1993). Nonetheless, the apparent Km is also almost an order of magnitude greater than would be expected if hexokinase I were totally rate-limiting (Weil-Malherbe and Bone, 1951;Fromm and Zewe, 1962 ;Katzen and Schimke, 1965).…”

Section: Discussionmentioning

confidence: 93%

Coupled Glucose Transport and Metabolism in Cultured Neuronal Cells: Determination of the Rate-Limiting Step

Whitesell

Ward

McCall

et al. 1995

J Cereb Blood Flow Metab

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Summary: In brain and nerves the phosphorylation of glucose, rather than its transport, is generally considered the major rate-limiting step in metabolism. Since little is known regarding the kinetic coupling between these pro cesses in neuronal tissues, we investigated the transport and phosphorylation of [2-3H)glucose in two neuronal cell models: a stable neuroblastoma cell line (NCB20), and a primary culture of isolated rat dorsal root ganglia cells. When transport and phosphorylation were measured in series, phosphorylation was the limiting step. because in tracellular glucose concentrations were the same as those outside of cells, and because the apparent Km for glucose utilization was lower than expected for the transport step. However, the apparent Km was still severalfold higher than the Km of hexokinase I. When [2-3H)glucose efflux and phosphorylation were measured from the same intra- 814 cellular glucose pool in a parallel assay, rates of glucose efflux were three-to-fivefold greater than rates of phos phorylation. With the parallel assay, we observed that activation of glucose utilization by the sodium channel blocker veratridine caused a selective increase in glucose phosphorylation and was without effect on glucose trans port. In contrast to results with glucose, both cell types accumulated 2-deoxY-D-[1 4 C)glucose to concentrations severalfold greater than extracellular concentrations. We conclude from these studies' that glucose utilization in neuronal cells is phosphorylation-limited, and that the coupling between transport and phosphorylation depends on the type of hexose used.

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Section: Discussionmentioning

confidence: 93%

Coupled Glucose Transport and Metabolism in Cultured Neuronal Cells: Determination of the Rate-Limiting Step

Whitesell

Ward

McCall

et al. 1995

J Cereb Blood Flow Metab

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“…Glucose transporter3-mediated glucose transport is less extensively characterized than GLUT1-dependent transport. 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).…”

Section: Kinetics Of Glucose Transportmentioning

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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“…Conversely, GLUT5 has little or no affinity for glucose, but instead has a high affinity for fructose, and is considered to be responsible for most of the fructose uptake in the small intestine . Fructose is also transported by GLUT2, though with a much lower affinity than for glucose (Colville et al, 1993).…”

mentioning

confidence: 99%

Molecular and cellular regulation of glucose transporter (GLUT) proteins in cancer

Macheda

Rogers

Best

2004

Journal Cellular Physiology

1,054

893

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Malignant cells are known to have accelerated metabolism, high glucose requirements, and increased glucose uptake. Transport of glucose across the plasma membrane of mammalian cells is the first rate-limiting step for glucose metabolism and is mediated by facilitative glucose transporter (GLUT) proteins. Increased glucose transport in malignant cells has been associated with increased and deregulated expression of glucose transporter proteins, with overexpression of GLUT1 and/or GLUT3 a characteristic feature. Oncogenic transformation of cultured mammalian cells causes a rapid increase of glucose transport and GLUT1 expression via interaction with GLUT1 promoter enhancer elements. In human studies, high levels of GLUT1 expression in tumors have been associated with poor survival. Studies indicate that glucose transport in breast cancer is not fully explained by GLUT1 or GLUT3 expression, suggesting involvement of another glucose transporter. Recently, a novel glucose transporter protein, GLUT12, has been found in breast and prostate cancers. In human breast and prostate tumors and cultured cells, GLUT12 is located intracellularly and at the cell surface. Trafficking of GLUT12 to the plasma membrane could therefore contribute to glucose uptake. Several factors have been implicated in the regulation of glucose transporter expression in breast cancer. Hypoxia can increase GLUT1 levels and glucose uptake. Estradiol and epidermal growth factor, both of which can play a role in breast cancer cell growth, increase glucose consumption. Estradiol and epidermal growth factor also increase GLUT12 protein levels in cultured breast cancer cells. Targeting GLUT12 could provide novel methods for detection and treatment of breast and prostate cancer.

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Kinetic analysis of the liver-type (GLUT2) and brain-type (GLUT3) glucose transporters in Xenopus oocytes: substrate specificities and effects of transport inhibitors

Cited by 155 publications

References 28 publications

Coupled Glucose Transport and Metabolism in Cultured Neuronal Cells: Determination of the Rate-Limiting Step

Coupled Glucose Transport and Metabolism in Cultured Neuronal Cells: Determination of the Rate-Limiting Step

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

Molecular and cellular regulation of glucose transporter (GLUT) proteins in cancer

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