Disease relevance of GLUT4

• CONCLUSION: This study demonstrates that significant elevations in glucagon and insulin and reductions in total skeletal muscle GLUT1 and GLUT4 content all contribute to hyperoxia-induced hyperglycemia seen in newborns [1].
• In conclusion, 12 weeks of streptozotocin diabetes in swine caused a significant decrease in myocardial GLUT4 protein and a decrease in myocardial glucose uptake during ischemia [2].

High impact information on GLUT4

• Assessment of 2-deoxy-glucose uptake in a small isolated muscle, flexor carpi radialis, showed that the 26L group, which had suboptimal energy balance and the greatest GLUT4 expression, had the highest insulin-independent glucose uptake but the lowest insulin-dependent increment: 20% compared with 70% in the other groups [3].
• Insulin stimulates glucose transport largely by mediating translocation of the insulin-sensitive glucose transporter (GLUT4) from an intracellular compartment to the plasma membrane [4].
• AIMS/HYPOTHESIS: To identify a GTPase of 24,000 M(r) which we recently found to co-localize with GLUT4 in cardiac muscle [5].
• Co-localization with GLUT4 was assessed by continuous sucrose density gradient fractionation and immunoadsorption of GLUT4-containing vesicles [5].
• In preconditioned myocardium, activation of the mitogen-activated protein kinase (MAPK) p38 leads to increased glucose uptake via enhanced GLUT-4 translocation [6].

Chemical compound and disease context of GLUT4

• The purpose of this study was to elucidate potential mechanisms underlying the hyperoxic-induced hyperglycemia by examining glucagon, insulin, and epinephrine, which are important in glucose regulation and skeletal and cardiac glucose transporters (GLUT1 and GLUT4), which facilitate glucose entry [1].

Biological context of GLUT4

• Nucleotide sequences 1-138 and 139-246 of the GLUT4 cDNA share 78% sequence identity with exon 4a and 91% sequence identity with exon 4b of the human GLUT4 gene, respectively [7].
• Development of a sensitive assay to quantify GLUT4 mRNA in porcine adipose tissue will enable us to conduct studies to increase our understanding of the molecular mechanisms by which porcine somatotropin (pST) regulates GLUT4 gene expression [7].
• Dobutamine infusion resulted in similar increases in cardiac contractility, oxygen consumption, and glucose uptake in both groups despite reductions of 50-65% in GLUT-4 and GLUT-1 protein in the diabetic group [8].

Anatomical context of GLUT4

• When porcine adipose tissue explants were cultured in the presence of insulin (10 ng/mL), GLUT4 mRNA abundance was increased [7].
• These findings show that only rat adipocytes, which are beta3-adrenergic-responsive, respond to chronic beta3-AR agonist by an increase of GLUT4 content and MAO activity, despite a desensitization of all beta-adrenoceptor subtypes [9].
• GLUT4 was present in membranes from BAT of both warm- and cold-acclimated guinea pigs [10].
• Total GLUT1 and GLUT4 content in cardiac and skeletal muscle was measured using Western blotting analysis [1].
• GLUT4 translocation was analyzed using subcellular fractionation techniques to isolate partially purified plasma membranes and cytoplasmic vesicles and using Western blotting [11].

Associations of GLUT4 with chemical compounds

• The GLUT4 cDNA fragment was subcloned into pGEM-4Z vector to synthesize a highly specific riboprobe that hybridized only to human GLUT4 cDNA but not to human glucose transporter 1 (GLUT1) cDNA [7].
• In 5 additional hibernating pigs studied under resting fasted conditions, FDG uptake and GLUT4 translocation were also higher in the LAD region, in the absence of dobutamine stimulation [12].
• Similarly, mRNA abundance for acetyl-coenzyme A carboxylase and the glucose transport proteins Glut 1 and Glut 4 were not affected by Rac in either adipose depot [13].

Other interactions of GLUT4

• The adipose tissue glucose transporter 4, fatty acid synthase, and leptin transcript concentrations were greater (P < .05) in obese than in lean pigs [14].
• Porcine somatotrophin differentially down-regulates expression of the GLUT4 and fatty acid synthase genes in pig adipose tissue [15].
• LAD/LADc ratios were increased for hexokinase (1.69), phosphofructokinase (3.69), and glyceraldehyde-3-phosphate dehydrogenase (2.29) in the ischemia heart and for phosphofructokinase (3.90), glyceraldehyde-3-phosphate dehydrogenase (2.20), GLUT 4 (1.55) and GLUT 1 (2.20) in the ischemia/reflow heart [16].

Analytical, diagnostic and therapeutic context of GLUT4

• A 246-bp fragment of porcine glucose transporter 4 (GLUT4) cDNA was cloned by polymerase chain reaction (PCR) from porcine adipose tissue RNA [7].
• After the animals were killed, the LAD region showed a higher content of GLUT4 by immunoblots and a greater degree of translocation as estimated by immunohistochemistry [12].
• A novel competitive enzyme-linked immunosorbent assay (ELISA) for measuring the insulin-regulatable glucose transporter (GLUT4) has been developed in our laboratory [17].

References