Acute regulation of glucose transport in a monocyte–macrophage cell line: Glut-3 affinity for glucose is enhanced during the respiratory burst

Abstract

Activation of the respiratory burst imposes acute metabolic demands on phagocytic cells. These are met by mobilizing internal energy stores and by increasing the utilization of exogenous energy, including glucose in the circulation. To determine whether the increased glucose uptake that is known to be associated with the respiratory burst involves the regulation of glucose transporter molecules, the intrinsic transport properties of glucose transporters on the macrophage cell line RAW 264.7 were determined after activation with PMA, N-formyl-methionine-leucine-phenylalanine (fMLP) and the cytokines granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin 3 (IL-3). Treatment with PMA resulted in a 2-fold increase in respiratory burst activity within 10 min; this was associated with a 30-50% increase in 2-deoxyglucose uptake and a 4-fold increase in transporter affinity for glucose. Similarly, fMLP, GM-CSF and IL-3 treatments stimulated 2-deoxyglucose uptake that was associated with a 3-4-fold increase in transporter affinity for glucose. To determine whether the changes observed in 2-deoxyglucose uptake in response to PMA, fMLP and growth factors were influenced by phosphorylation of the sugar, 3-O-methylglucose, which is not phosphorylated, was used. Increased 3-O-methylglucose uptake and increased transporter affinity for glucose were also observed after PMA, fMLP and GM-CSF treatments. Whereas both fMLP and GM-CSF stimulated superoxide production, IL-3 failed to activate respiratory burst activity. The protein kinase inhibitors genistein and staurosporine inhibited the increase in 2-deoxyglucose uptake observed with fMLP and GM-CSF, and partly reversed the affinity increase towards that of untreated control cells. In contrast, the phosphatidylinositol 3-kinase inhibitor wortmannin had little effect on 2-deoxyglucose uptake in response to these activators. Western blotting with subtype-specific antisera showed that Glut-3 was the predominant transporter on RAW 264.7 cells. These studies demonstrate that acute regulation of glucose transporters occurs in response to activators that promote respiratory burst activity, and show that this regulation involves both tyrosine kinases and protein kinase C activity.

Modeling the Physiological Factors Affecting Glucose Sensor Function in Vivo

“…The consumption of glucose by inflammatory macrophages is mediated by glucose surface receptors and has been well characterized in numerous studies. 25,26 Those studies have shown that cellular glucose uptake agrees well with the MichaelisMenten formalism for enzymatic activity. As a result, consumption can be modeled using Michaelis-Menten kinetics with values specific to glucose uptake by macrophages.…”

Comparison of Contrast Agents for Atherosclerosis Imaging Using Cultured Macrophages: FDG Versus Ultrasmall Superparamagnetic Iron Oxide

“…We found that GLUT-1 and GLUT-3, which are major isoforms of a glucose transporter in macrophages (12,13), were significantly upregulated in M1 macrophages, compared with M2 macrophages (Fig. 3) (P , 0.01 and , 0.01, respectively).…”

Inhibition of Development of Abdominal Aortic Aneurysm by Glycolysis Restriction

“…GLUT-1 is the major isoform found in most cells, whereas GLUT-3 leads to a substantial increase in energy needs associated with cell activation by its high affinity for glucose 30 and is a major GLUT subtype for macrophages. [31][32][33] Both GLUT-1 and GLUT-3 immunoreactivity were shown to be distributed in macrophages of the aneurysmal wall, indicating that glycolysis is the preferred energy production of these cells than the other cell types constituted of aorta. Importantly, the magnitude of GLUT-3 expression was associated with MMP-9 activity, mainly produced from macrophages in aneurysmal tissues, 34 and this was comparable in a monocytic cell line, showing the substantial increase in syntheses in GLUT-3 and MMP-9 upon the differentiation to macrophages.…”