Developmental Alterations of Intestinal SGLT1 and GLUT2 Induced by Early Weaning Coincides with Persistent Low-Grade Metabolic Inflammation in Female Pigs

Early life adversity (ELA) is linked with the increased risk for inflammatory and metabolic diseases in later life but the mechanisms remain poorly understood. Intestinal epithelial glucose transporters SGLT1 and GLUT2 are the major route for intestinal glucose uptake but have also received increased attention as modulators of inflammatory and metabolic diseases. Here we tested the hypothesis that early weaning (EW) in pigs, an established model of ELA, alters the development of epithelial glucose transporters and coincides with elevated markers of metabolic inflammation. Jejunum and ileum of 90 d old pigs previously exposed to EW (16 d wean age), exhibited reduced SGLT1 activity (by ~ 30%, P<0.05), compared with late weaned (LW, 26 d wean age) controls . In contrast, GLUT2-mediated glucose transport was increased (P = 0.003) in EW pigs compared with LW pigs. Reciprocal changes in SGLT1 and GLUT2-mediated transport coincided with transporter protein expression in the intestinal brush border membranes (BBM) that were observed at 90 d and 150 d of age. Ileal SGLT1-mediated glucose transport and BBM expression were Inhibited by the β-adrenergic receptor (βAR) blocker propranolol in EW and LW pigs. In contrast, propranolol enhanced ileal GLUT2-mediated glucose transport (P=0.015) and BBMV abundance (P=0.035) LW pigs, but not EW pigs. Early weaned pigs exhibited chronic elevated blood glucose and C-Reactive Protein (CRP) levels, and adipocyte hypertrophy and upregulated adipogenesis-related gene expression in visceral adipose tissue. Altered development of intestinal glucose transporters by EW could underlie the increased risk for later life inflammatory and metabolic diseases.

Human Glucose Transporters in Renal Glucose Homeostasis

The kidney plays an important role in glucose homeostasis by releasing glucose into the blood stream to prevent hypoglycemia. It is also responsible for the filtration and subsequent reabsorption or excretion of glucose. As glucose is hydrophilic and soluble in water, it is unable to pass through the lipid bilayer on its own; therefore, transport takes place using carrier proteins localized to the plasma membrane. Both sodium-independent glucose transporters (GLUT proteins) and sodium-dependent glucose transporters (SGLT proteins) are expressed in kidney tissue, and mutations of the genes coding for these glucose transporters lead to renal disorders and diseases, including renal cancers. In addition, several diseases may disturb the expression and/or function of renal glucose transporters. The aim of this review is to describe the role of the kidney in glucose homeostasis and the contribution of glucose transporters in renal physiology and renal diseases.

Differential Expression of Glucose Transporter Proteins GLUT-1, GLUT-3, GLUT-8 and GLUT-12 in the Placenta of Macrosomic, Small-for-Gestational-Age and Growth-Restricted Foetuses

Placental transfer of glucose constitutes one of the major determinants of the intrauterine foetal growth. The objective of the present study was to evaluate the expression of glucose transporter proteins GLUT-1, GLUT-3, GLUT-8 and GLUT-12 in the placenta of macrosomic, small-for-gestational-age (SGA) and growth-restricted foetuses (FGR). A total of 70 placental tissue samples were collected from women who delivered macrosomic ≥4000 g (n = 26), SGA (n = 11), growth-restricted (n = 13) and healthy control neonates (n = 20). Computer-assisted quantitative morphometry of stained placental sections was performed to determine the expression of selected GLUT proteins. Immunohistochemical staining identified the presence of all glucose transporters in the placental tissue. Quantitative morphometric analysis performed for the vascular density-matched placental samples revealed a significant decrease in GLUT-1 and increase in GLUT-3 protein expression in pregnancies complicated by FGR as compared to other groups (p < 0.05). In addition, expression of GLUT-8 was significantly decreased among SGA foetuses (p < 0.05). No significant differences in GLUTs expression were observed in women delivering macrosomic neonates. In the SGA group foetal birth weight (FBW) was negatively correlated with GLUT-3 (rho = −0.59, p < 0.05) and positively with GLUT-12 (rho = 0.616, p < 0.05) placental expression. In addition, a positive correlation between FBW and GLUT-12 expression in the control group (rho = 0.536, p < 0.05) was noted. In placentas derived from FGR-complicated pregnancies the expression of two major glucose transporters GLUT-1 and GLUT-3 is altered. On the contrary, idiopathic foetal macrosomia is not associated with changes in the placental expression of GLUT-1, GLUT-3, GLUT-8 and GLUT-12 proteins.

Genetic evidence that uptake of the fluorescent analog 2NBDG occurs independently of known glucose transporters

The fluorescent derivative of glucose, 2-Deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)-amino]-D-glucose (2NBDG), is a widely used surrogate reagent to visualize glucose uptake in live cells at single cell resolution. Using a model of CRISPR-Cas9 gene editing in 5TGM1 myeloma cells, we demonstrate that ablation of the glucose transporter gene Slc2a1 abrogates radioactive glucose uptake but has no effect on the magnitude or kinetics of 2NBDG import. Extracellular 2NBDG, but not NBD-fructose was transported by plasma cells into the cytoplasm suggesting specific activity that is unlinked to glucose import and that of chemically similar compounds. RNA-Seq analysis of primary plasma cells and the 5TGM1 myeloma cell line revealed expression of other candidate glucose transporters. Yet, deletion of these transporters individually or in combination with one another also had no impact on 2NBDG uptake. Ablation of the genes in the Slc29 and Slc35 families of nucleoside and nucleoside sugar transporters as well as the ATP-binding cassette (ABC) transporter family also failed to impact 2NBDG import. Thus, cellular uptake of 2NBDG is promoted by an unknown mechanism and is not a faithful indicator of glucose transport.

Effect of photobiomodulation therapy on the regulation of glucose uptake by lymphocytes in diabetes mellitus (Review)

For most cells, including lymphocytes, glucose is a primary energy source, and, therefore, it is vital to understand the regulatory mechanisms that control the work of glucose transporters. Lymphocytes are pivotal for mediation of immune and inflammatory responses. A feature of lymphocytes is increasing glucose utilization during activation of the immune function, which is strongly dependent on glucose uptake. Some studies show that elevated glucose concentration in diabetes mellitus affects lymphocytes’ glucose transporters expression, whichcorrelates with impaired immune functions and may become one of the predisposing factors of contracting infectious diseases. Recent studies have focused on glucose transporters as therapeutic targets for a variety of diseases, including diabetes mellitus. This review demonstrates the effect of photobiomodulationtherapy on glucose uptake by Na+-coupled glucose carrier SGLT1 and facilitated diffusion glucose carriers of the GLUT family (GLUT1, GLUT3, GLUT4) in normal and diabetic lymphocytes.

TAMI-27. METABOLIC MANIPULATION OF T CELLS TO TREAT BRAIN TUMORS

INTRODUCTION Glioblastoma are a challenge for neuro-oncologists and current therapies are minimally effective. Standard-of- care treatment is almost inevitably followed by disease recurrence. Adoptive T cell transfer has emerged as a viable therapeutic for brain malignancies. While promising, the efficacy of this approach is often limited by a complex immunosuppressive tumor microenvironment. These complexities mean that more sophisticated T cell products are required. OBJECTIVES The brain tumor microenvironment provides local restraints via metabolic competition suppressing antitumor immunity, specifically inhibiting infiltration and tumoricidal functions of host and adoptively transferred tumor-reactive T cells. The overall goal of this project is to test new treatments to reverse immune dysfunction in cancer through the regulation of T cell metabolic signaling. We propose that modulating glucose pathway in T cells can potentiate their anti-tumor activity once adoptively transferred. METHODS T cells glucose metabolic pathway was modulated via glucose transporters overexpression. The functionality of metabolically modified T cells was investigated in murine and human models. RESULTS We demonstrated the existence of a competition for glucose between T cells and tumor cells, with tumor cells imposing glucose restriction mediating T cell hyporesponsiveness. Overexpression of glucose transporters such as Glut1 and Glut3 increased T cell glucose utilization and provide survival/growth advantage and enhanced T cell activation in glucose-restricted conditions. We also established that glucose transporter overexpression improves intratumoral infiltration of adoptively transferred T cells. CONCLUSION This project integrates fundamental concepts of tumor and immune metabolism in the design of immunotherapy and confirms that immunometabolism represents a viable target for new cancer therapy to treat brain tumors.

Litopenaeus vannamei BMAL1 Is a Critical Mediator Regulating the Expression of Glucose Transporters and Can Be Suppressed by Constant Darkness

Aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) is a core circadian transcription factor that controls the 24-h cycle of physiological processes. In shrimp, the role of BMAL1 in the regulating glucose metabolism remains unclear. Firstly, we observed that the daily profile of BMAL1, GLUT1 and SGLT1 expression were synchronized in the intestine and the hepatopancreas of Litopenaeus vannamei. Then we examined the effects of BMAL1 on the gene expression of glucose transporter type 1 (SGLT1) and sodium-glucose cotransporter 1 (GLUT1) in vivo and in vitro. BMAL1 in L. vannamei shares 70.91–96.35% of sequence identities with other shrimp species and possesses the conserved helix-loop-helix domain and polyadenylation site domain. The in vitro dual-luciferase reporter assay and in vivo RNA interference experiment demonstrated that BMAL1 exerted a positive regulation effect on the expression of glucose transporters in L. vannamei. Moreover, we conducted an eight-week treatment to investigate whether light/dark cycle change would influence growth performance, and gene expression of BMAL1, GLUT1 and SGLT1 in L. vannamei. Our result showed that compared with natural light treatment, constant darkness (24-hour darkness) significantly decreased (P < 0.05) serum glucose concentration, and suppressed (p < 0.05) the gene expression of BMAL1, GLUT1 and SGLT1 in the hepatopancreas and the intestine. Growth performance and survival rate were also decreased (p < 0.05) by constant darkness treatment. Our result identified BMAL1 as a critical mediator regulating the expression of glucose transporters, which could be suppressed by constant darkness in L. vannamei. It would be quite interesting to explore the mechanism of dark/light cycles on glucose transport and metabolism in L. vannamei, which might provide a feeding strategy for improving carbohydrate utilization in the future.