Insulin stimulates membrane fusion and GLUT4 accumulation in clathrin coats on adipocyte plasma membranes
Authors
Huang, ShaohuiLifshitz, Lawrence M.
Jones, Christine
Bellve, Karl D.
Standley, Clive
Fonseca, Sonya G.
Corvera, Silvia
Fogarty, Kevin E.
Czech, Michael P.
UMass Chan Affiliations
Program in Gene Function and ExpressionDepartment of Physiology
Program in Molecular Medicine
Graduate School of Biomedical Sciences
Document Type
Journal ArticlePublication Date
2007-03-07Keywords
3T3-L1 Cells; Adipocytes; Animals; Cell Membrane; Clathrin; Exocytosis; Glucose Transporter Type 4; Insulin; Kinetics; Membrane Fusion; Mice; Microscopy, Fluorescence; Time FactorsLife Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
Total internal reflection fluorescence (TIRF) microscopy reveals highly mobile structures containing enhanced green fluorescent protein-tagged glucose transporter 4 (GLUT4) within a zone about 100 nm beneath the plasma membrane of 3T3-L1 adipocytes. We developed a computer program (Fusion Assistant) that enables direct analysis of the docking/fusion kinetics of hundreds of exocytic fusion events. Insulin stimulation increases the fusion frequency of exocytic GLUT4 vesicles by approximately 4-fold, increasing GLUT4 content in the plasma membrane. Remarkably, insulin signaling modulates the kinetics of the fusion process, decreasing the vesicle tethering/docking duration prior to membrane fusion. In contrast, the kinetics of GLUT4 molecules spreading out in the plasma membrane from exocytic fusion sites is unchanged by insulin. As GLUT4 accumulates in the plasma membrane, it is also immobilized in punctate structures on the cell surface. A previous report suggested these structures are exocytic fusion sites (Lizunov et al., J. Cell Biol. 169:481-489, 2005). However, two-color TIRF microscopy using fluorescent proteins fused to clathrin light chain or GLUT4 reveals these structures are clathrin-coated patches. Taken together, these data show that insulin signaling accelerates the transition from docking of GLUT4-containing vesicles to their fusion with the plasma membrane and promotes GLUT4 accumulation in clathrin-based endocytic structures on the plasma membrane.Source
Mol Cell Biol. 2007 May;27(9):3456-69. Epub 2007 Mar 5. Link to article on publisher's siteDOI
10.1128/MCB.01719-06Permanent Link to this Item
http://hdl.handle.net/20.500.14038/33863PubMed ID
17339344Related Resources
Link to Article in PubMedae974a485f413a2113503eed53cd6c53
10.1128/MCB.01719-06