title: Identification of novel insulin mimetic drugs by quantitative total internal reflection fluorescence (TIRF) microscopy.
abstract: OBJECTIVE
  Insulin stimulates the transport of glucose in target tissues by triggering the translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Resistance to insulin, the major abnormality in type 2 diabetes, results in a decreased GLUT4 translocation efficiency. Thus, special attention is being paid to search for compounds that are able to enhance this translocation process in the absence of insulin.
  
  
  METHODS
  Total internal reflection fluorescence (TIRF) microscopy was applied to quantify GLUT4 translocation in highly insulin-sensitive CHO-K1 cells expressing a GLUT4-myc-GFP fusion protein.
  
  
  RESULTS
  Using our approach, we demonstrated GLUT4 translocation modulatory properties of selected substances and identified novel potential insulin mimetics. An increase in the TIRF signal was found to correlate with an elevated glucose uptake. Variations in the expression level of the human insulin receptor (hInsR) showed that the insulin mimetics identified stimulate GLUT4 translocation by a mechanism that is independent of the presence of the hInsR.
  
  
  CONCLUSIONS
  Taken together, the results indicate that TIRF microscopy is an excellent tool for the quantification of GLUT4 translocation and for identifying insulin mimetic drugs.
authors.affiliation: School of Engineering and Environmental Sciences, University of Applied Sciences Upper Austria, Wels, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Lanzerstorfer
authors.forename: Verena
authors.initials: V
authors.lastname: Stadlbauer
authors.forename: Lilia A
authors.initials: LA
authors.lastname: Chtcheglova
authors.forename: Renate
authors.initials: R
authors.lastname: Haselgrübler
authors.forename: Daniela
authors.initials: D
authors.lastname: Borgmann
authors.forename: Jürgen
authors.initials: J
authors.lastname: Wruss
authors.forename: Peter
authors.initials: P
authors.lastname: Hinterdorfer
authors.forename: Klaus
authors.initials: K
authors.lastname: Schröder
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Winkler
authors.forename: Otmar
authors.initials: O
authors.lastname: Höglinger
authors.forename: Julian
authors.initials: J
authors.lastname: Weghuber
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells; D002867:Chromones / Q000494:pharmacology; D003412:Cricetulus; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007329:Insulin Antagonists / Q000494:pharmacology; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D009025:Morpholines / Q000494:pharmacology; D021381:Protein Transport; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D011972:Receptor, Insulin / Q000378:metabolism; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D002867:Chromones; D051275:Glucose Transporter Type 4; D007328:Insulin; D007329:Insulin Antagonists; D009025:Morpholines; D016271:Proto-Oncogene Proteins c-myc; D049452:Green Fluorescent Proteins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D011972:Receptor, Insulin; D005947:Glucose; D000077191:Wortmannin