Abstract: Cellular glucose uptake via Glucose Transporter 4 (GLUT4) in adipose tissue and muscle cells is initialized by binding of extracellular insulin to its receptors in the plasma membrane. GLUT4 translocates from intracellular vesicles to the cell surface and facilitates glucose internalization. Insulin signaling is altered by a variety of diseases (e.g., diabetes mellitus type 2) and results in impaired glucose clearance of the blood. We visualized the translocation of GLUT4 to the plasma membrane after addition of soluble insulin using single-molecule-sensitive fluorescence microscopy. GLUT4 is genetically modified with eGFP. In order to distinguish between to the membrane translocated GLUT4 and vesicular GLUT4, we excite the cell membrane with an evanescent wave produced (total internal reflection configuration). Another possibility is formation of Giant Plasma Membrane Vesicles (GPMVs) of stimulated cells. The last approach reduces the influence of free GLUT4-eGFP near the membrane further. In contrast, we tested the localized stimulation with insulin using the functionalized tip of an atomic force microscope (AFM) cantilever. Thereby, insulin-coated beads were brought into contact with the cell. A localized significant increase of the translocated GLUT4-bound eGFP signal was found. Obviously, binding affinity is increased via surface immobilization in comparison to soluble insulin. The next step will be the functionalization of bionanoparticles like lipoproteins as carrier system. We speculate, that their intrinsic biocompatibility will enhance the viability of its cargo and should yield a prolonged steady basal insulin level in the body – thus stabilizing the blood glucose level.
|Translated title of the contribution||REAKTION DES GLUKOSETRANSPORTERS DURCH UNTERSCHIEDLICHE STIMULATION|
|Number of pages||1|
|Publication status||Published - 2018|