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. Author manuscript; available in PMC: 2014 Jan 10.
Published in final edited form as: Nat Med. 2011 Aug 14;17(9):1067–1075. doi: 10.1038/nm.2414

Figure 3.

Figure 3

Analyses of human islets from normal donors and donors with type 2 diabetes. (a) Subcellular localization of FOXA2 and HNF1A proteins in human beta cells from normal donors and donors with type 2 diabetes (T2D). Results represent analyses of six normal islet samples and two T2D islet samples. Propidium iodide (PI) staining of the nucleus (red) is included where indicated. (b) Abundance of mRNA produced from MGAT4A, SLC2A1, SLC2A2 and INS genes in the designated human islet cells. (c) Islet cell surface abundance of the DSA lectin-binding glycan produced by the GnT-4a glycosyltransferase. (d) Islet cell surface expression of human GLUT-1 and GLUT-2 glucose transporters. (e) Glucose transport activity of the indicated human islets measured using the fluorescent glucose analog 2-NBDG. (f) Glucose-stimulated insulin secretion assayed in islet cell cultures containing medium bearing the indicated concentrations of glucose. (g) Left, GLUT-1 and GLUT-2 glycoproteins were immunoprecipitated (IP) from normal human islet cell extracts followed by electrophoresis and analyses with the indicated antibodies and lectins. Right, deduced tetra-antennary N-glycan structure residing on both human islet cell GLUT-1 and GLUT-2 bearing undersialylated glycan branch termini (+/−). Gray circle, core β1-4GlcNAc linkage produced by GnT-4a. (h) Normal human islet cells were cultured with or without the indicated glycans (10 mM) for 2 h before analyses of cell surface GLUT-1 and GLUT-2 expression by flow cytometry. (i) Fluorescent glucose analog (2-NBDG) transport (left) and GSIS activity (right) measured among islet cells treated in h. The results in h and i represent analyses of three islet cell samples from normal human donors. (j) siRNA knockdown of GLUT1 and GLUT2 mRNA in normal human islet cell cultures measured at 72 h (left four graphs). Glucose analog 2-NBDG transport and GSIS activity were also measured at 72 h. Data are expressed as means ± s.e.m. from six normal human islet donors and two human donors with T2D, unless otherwise stated. *P = 0.01–0.04; **P = 0.002–0.005; ***P = 0.0002–0.0005; ****P < 0.0001 (Student’s t test).