Article

Rab10 and myosin-Va mediate insulin-stimulated GLUT4 storage vesicle translocation in adipocytes

Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
The Journal of Cell Biology (Impact Factor: 9.69). 08/2012; 198(4):545-560. DOI: 10.1083/jcb.201111091
Source: PubMed

ABSTRACT Rab proteins are important regulators of insulin-stimulated GLUT4 translocation to the plasma membrane (PM), but the precise
steps in GLUT4 trafficking modulated by particular Rab proteins remain unclear. Here, we systematically investigate the involvement
of Rab proteins in GLUT4 trafficking, focusing on Rab proteins directly mediating GLUT4 storage vesicle (GSV) delivery to
the PM. Using dual-color total internal reflection fluorescence (TIRF) microscopy and an insulin-responsive aminopeptidase
(IRAP)-pHluorin fusion assay, we demonstrated that Rab10 directly facilitated GSV translocation to and docking at the PM.
Rab14 mediated GLUT4 delivery to the PM via endosomal compartments containing transferrin receptor (TfR), whereas Rab4A, Rab4B,
and Rab8A recycled GLUT4 through the endosomal system. Myosin-Va associated with GSVs by interacting with Rab10, positioning
peripherally recruited GSVs for ultimate fusion. Thus, multiple Rab proteins regulate the trafficking of GLUT4, with Rab10
coordinating with myosin-Va to mediate the final steps of insulin-stimulated GSV translocation to the PM.

0 Followers
 · 
187 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recycling of endocytic receptors to the cell surface involves passage through a series of membrane-bound compartments by mechanisms that are poorly understood. In particular, it is unknown if endocytic recycling requires the function of multisubunit tethering complexes, as is the case for other intracellular trafficking pathways. Herein we describe a tethering complex named endosome-associated recycling protein (EARP) that is structurally related to the previously described Golgi-associated retrograde protein (GARP) complex. The two complexes share the Ang2, Vps52 and Vps53 subunits, but EARP contains an uncharacterized protein, syndetin, in place of the Vps54 subunit of GARP. This change determines differential localization of EARP to recycling endosomes and GARP to the Golgi complex. EARP interacts with the target SNARE syntaxin 6 and various cognate SNAREs. Depletion of syndetin or syntaxin 6 delays recycling of internalized transferrin to the cell surface. These findings implicate EARP in canonical membrane-fusion events in the process of endocytic recycling.
    Nature Cell Biology 03/2015; 17(5). DOI:10.1038/ncb3129 · 20.06 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Total internal reflection fluorescence microscope has often been used to study the molecular mechanisms underlying vesicle exocytosis. However, the spatial occurrence of the fusion events within a single cell is not frequently explored due to the lack of sensitive and accurate computer-assisted programs to analyze large image data sets. Here, we have developed an image analysis platform for the nonbiased identification of different types of vesicle fusion events with high accuracy in different cell types. By performing spatiotemporal analysis of stimulus-evoked exocytosis in insulin-secreting INS-1 cells, we statistically prove that individual vesicle fusion events are clustered at hotspots. This spatial pattern disappears upon the disruption of either the actin or the microtubule network; this disruption also severely inhibits evoked exocytosis. By demonstrating that newcomer vesicles are delivered from the cell interior to the surface membrane for exocytosis, we highlight a previously unappreciated mechanism in which the cytoskeleton-dependent transportation of secretory vesicles organizes exocytosis hotspots in endocrine cells.
    Biophysical Journal 01/2015; 108(2). DOI:10.1016/j.bpj.2014.11.3462 · 3.83 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Dear Editor,Intracellular trafficking is a basis of cellular activities, including cell migration, immune response, and development (Lebreton et al., 2003; Lučin et al., 2014; Ulrich and Heisenberg, 2009). In healthy tissue, intracellular trafficking is highly regulated, controlling the form and function of cells (Furthauer and Gonzalez-Gaitan, 2009). Work carried out in animals and plants highlights that regulated intracellular trafficking is important for the development of multicellular organisms (Fürthauer and González-Gaitán, 2009; Kolotuev et al., 2009; Richter et al., 2009). As a family of Ras-related small GTPase, Rabs function as coordinators for diverse aspects of intracellular trafficking including vesicle budding and formation, cargo sorting and transport to target membranes, and recruitment of key molecules (Stenmark, 2009; Zerial and McBride, 2001).Rab10, widely distributed in intracellular membranes, is highly conserved from Caenorhabditis elegans (C. elegans) to humans. ...
    Protein & Cell 04/2015; 6(6). DOI:10.1007/s13238-015-0150-8 · 2.85 Impact Factor