Rab11 is associated with GLUT4-containing vesicles and redistributes in response to insulin

Citation
A. Kessler et al., Rab11 is associated with GLUT4-containing vesicles and redistributes in response to insulin, DIABETOLOG, 43(12), 2000, pp. 1518-1527
Citations number
49
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Endocrynology, Metabolism & Nutrition","Endocrinology, Nutrition & Metabolism
Journal title
DIABETOLOGIA
ISSN journal
0012-186X → ACNP
Volume
43
Issue
12
Year of publication
2000
Pages
1518 - 1527
Database
ISI
SICI code
0012-186X(200012)43:12<1518:RIAWGV>2.0.ZU;2-I
Abstract
Aims/hypothesis. To identify a GTPase of 24 000 M-r which we recently found to co-localize with GLUT4 in cardiac muscle. Methods. A 24 000 M-r-GTP-binding fraction was purified from pig heart by a three-step chromatographic procedure, followed by two-dimensional electrop horesis and electrospray ionization-mass spectrometry, Subcellular distribu tion of the GTPase was assessed by western blotting. Go-localization with G LUT4 was assessed by continuous sucrose density gradient fractionation and immunoadsorption of GLUT4-containing vesicles. Results. The Rab11 protein was identified as a major component of the GTP-b inding fraction and its expression in rat cardiac muscle was confirmed. In vivo insulin treatment resulted in the recruitment of Rab11 from the micros omal fraction to the plasma membrane. Subcellular fractionation indicated t wo immunoreactive GLUT4 pools. Most of the intracellular pool of Rab11 over lapped with the high-density GLUT4 pool and most of the transferrin recepto r pool. The Rab11 protein also co-sedimented with the low-density, non-endo somal GLUT4 pool and substantially increased in this fraction after insulin treatment. It was specifically present in GLUT4-containing vesicles and in sulin increased its abundance in these vesicles 2.2-fold relative to the am ount of GLUT4. These vesicles also containend Rab4 and Akt-2, the latter be ing only associated after insulin stimulation. Insulin was unable to alter the cellular localization of Rab11 in insulin-resistant obese Zucker rats. Conclusion/interpretation. These results support the hypothesis that at lea st two GTPases of the Rab family participate in GLUT4-vesicle trafficking. We suggest that Rab11 is involved in the endosomal recycling, sorting and e xocytotic movement of the glucose transporter.