Exocytosis: The Many Masters of the Exocyst

Lipschutz, Joshua H.; Mostov, Keith E.

doi:10.1016/s0960-9822(02)00753-4

Cited by 212 publications

(160 citation statements)

References 19 publications

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“…Recent insights into structure of the exocyst have shed light on the architecture and function of this complex, suggesting that the exocyst assembles into an overall rodlike structure, in the process bridging the vesicles to their target membrane (5,6). Consistent with this notion, the exocyst has been found to concentrate on "hotspots" on the plasma membrane where exocytosis actively takes place and has been implicated in different types of membrane trafficking including polarized growth in yeast, neurite growth in the nervous system, glucose transport in fat cells, and basal-lateral trafficking in epithelial cells (4). Interestingly, in Saccharomyces cerevisiae and Schizosaccharomyces pombe, the exocyst complex localizes to the cleavage furrow and is essential for membrane delivery during cytokinesis (7)(8)(9).…”

mentioning

confidence: 68%

RalA-exocyst-dependent Recycling Endosome Trafficking Is Required for the Completion of Cytokinesis

Chen

Inoue

Hsu

et al. 2006

Journal of Biological Chemistry

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In eukaryotic cells, recycling endosome-mediated trafficking contributes to the completion of cytokinesis, in a manner under the control of the centrosome. We report that the exocyst complex and its interacting GTPase RalA play a critical role in this polarized trafficking process. RalA resides in the recycling endosome and relocates from the pericentrosomal region to key cytokinetic structures including the cleavage furrow, and later, the abscission site. This event is coupled to the dynamic redistribution of the exocyst proteins. These associate with the centrosome in interphase and concentrate on the central spindle/ midbody during cytokinesis. Disruption of RalA-exocyst function leads to cytokinesis failure in late stages, particularly abscission, resembling the cytokinesis defects induced by loss of centrosome function. These data suggest that RalA and the exocyst may regulate vesicle delivery to the centrosome-related abscission site during the terminal stage of cytokinesis, implicating RalA as a critical regulator of cell cycle progression.

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mentioning

confidence: 68%

RalA-exocyst-dependent Recycling Endosome Trafficking Is Required for the Completion of Cytokinesis

Chen

Inoue

Hsu

et al. 2006

Journal of Biological Chemistry

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“…Because vesicle tethering takes place before SNARE-mediated membrane fusion, spatial and temporal regulation of the exocyst is crucial to determining where and when exocytosis takes place. Consistent with this notion, the exocyst has been found to be under the control of a number of small GTPases in a variety of cells (for review, see Novick and Guo 2002;Lipschutz and Mostov 2002). In this article, we focus on the roles of the Rab and Rho proteins.…”

Section: Spatial and Kinetic Control Of Membrane Trafficking By Smallmentioning

confidence: 81%

Membrane Organization and Dynamics in Cell Polarity

Orlando¹,

Guo²

2009

Cold Spring Harbor Perspectives in Biology

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The establishment and maintenance of cell polarity is important to a wide range of biological processes ranging from chemotaxis to embryogenesis. An essential feature of cell polarity is the asymmetric organization of proteins and lipids in the plasma membrane. In this article, we discuss how polarity regulators such as small GTP-binding proteins and phospholipids spatially and kinetically control vesicular trafficking and membrane organization. Conversely, we discuss how membrane trafficking contributes to cell polarization through delivery of polarity determinants and regulators to the plasma membrane.

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“…Whereas the yeast exocyst communicates with several members of the Rho subfamily of small GTPases, including Cdc42p (Lipschutz and Mostov, 2002;Novick and Guo, 2002), in mammals, only RAL (RALA) and TC10 (RHOQ) GTPases have been shown to bind the exocyst (Inoue et al, 2003), and no link has been reported with CDC42. Recently, genetic and biochemical evidence have shown that both yeast and mammalian exocysts communicate with the ER-translocon via an interaction with the Sec61␤ subunit (Lipschutz et al, 2003;Toikkanen et al, 2003), suggesting a role in protein synthesis/translocation events.…”

Section: Introductionmentioning

confidence: 99%

A dual role for IQGAP1 in regulating exocytosis

Rittmeyer

Daniel

Hsu

et al. 2008

Journal of Cell Science

173

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Polarized secretion is a tightly regulated event generated by conserved, asymmetrically localized multiprotein complexes, and the mechanism(s) underlying its temporal and spatial regulation are only beginning to emerge. Although yeast Iqg1p has been identified as a positional marker linking polarity and exocytosis cues, studies on its mammalian counterpart, IQGAP1, have focused on its role in organizing cytoskeletal architecture, for which the underlying mechanism is unclear. Here, we report that IQGAP1 associates and co-localizes with the exocyst-septin complex, and influences the localization of the exocyst and the organization of septin. We further show that activation of CDC42 GTPase abolishes this association and inhibits secretion in pancreatic β-cells. Whereas the N-terminus of IQGAP1 binds the exocyst-septin complex, enhances secretion and abrogates the inhibition caused by CDC42 or the depletion of IQGAP1, the C-terminus, which binds CDC42, inhibits secretion. Pulse-chase experiments indicate that IQGAP1 influences protein-synthesis rates, thus regulating exocytosis. We propose and discuss a model in which IQGAP1 serves as a conformational switch to regulate exocytosis.

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Exocytosis: The Many Masters of the Exocyst

Abstract: The exocyst is a conserved eight-subunit complex involved in the docking of exocytic vesicles. The exocyst has now been identified as an effector for five small GTPases, including Sec4, Rho1, Rho3, Cdc42 and, most recently, RalA.

Cited by 212 publications

References 19 publications

RalA-exocyst-dependent Recycling Endosome Trafficking Is Required for the Completion of Cytokinesis

RalA-exocyst-dependent Recycling Endosome Trafficking Is Required for the Completion of Cytokinesis

Membrane Organization and Dynamics in Cell Polarity

A dual role for IQGAP1 in regulating exocytosis

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