Rho3 of <i>Saccharomyces cerevisiae</i>, Which Regulates the Actin Cytoskeleton and Exocytosis, Is a GTPase Which Interacts with Myo2 and Exo70

Robinson, Nicole; Guo, Lea; Imai, Jun; Toh‐e, Akio; Matsui, Yasuji; Tamanoi, Fuyuhiko

doi:10.1128/mcb.19.5.3580

Cited by 188 publications

(192 citation statements)

References 63 publications

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“…Thus, the multiple, and likely regulated, association of exocyst with various cellular structures may play a role in coordinating protein synthesis, vesicle trafficking and cytoskeletal organization to promote cell growth and cell differentiation. Furthermore, some potential exocyst regulators discovered to date include members of the small GTPase family such as Rho, Ral, Rab, and TC10 which are downstream messengers of many signaling pathways (8,19,(27)(28)(29)(30)(31). The establishment of in vitro exocyst reconstitution assay and the availability of exocyst subunit-specific monoclonal antibodies should allow us to further investigate the regulation of exocyst function in response to various intracellular and extracellular signals during development.…”

Section: Discussionmentioning

confidence: 99%

The Mammalian Exocyst, a Complex Required for Exocytosis, Inhibits Tubulin Polymerization

Wang

Liu

Adamson

et al. 2004

Journal of Biological Chemistry

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The exocyst is a 734-kDa complex essential for development. Perturbation of its function results in early embryonic lethality. Extensive investigation has revealed that this complex participates in multiple biological processes, including protein synthesis and vesicle/ protein targeting to the plasma membrane. In this article we report that the exocyst may also play a role in modulating microtubule dynamics. Using monoclonal antibodies, we observed that endogenous exocyst subunits co-localized with microtubules and mitotic spindles in normal rat kidney cells. To test for a functional relationship between the exocyst complex and microtubules, we established an in vitro exocyst reconstitution assay and studied exocyst effect on microtubule dynamics. We found that the exocyst complex reconstituted from eight recombinant exocyst subunits inhibited tubulin polymerization in vitro. Deletion of exocyst subunit sec5, sec6, sec15, or exo70 diminished its tubulin polymerization inhibition activity. Surprisingly, exocyst subunit exo70 itself was also capable of inhibiting tubulin polymerization, although exocyst complex with exo70 deletion did not lose its activity completely. Overexpression of exo70 in NRK cells resulted in microtubule network disruption and the formation of filopodia-like plasma membrane protrusions. The formation of these membrane protrusions was greatly hampered by stabilizing microtubules with taxol. Overexpression of exo84, an exocyst subunit that did not show tubulin polymerization inhibition activity, did not cause this phenotype. Results shown in this article, along with a previous report that localized microtubule instability induces plasma membrane addition, implicates a novel role for the exocyst in modulating microtubule dynamics underlying exocytosis.

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Section: Discussionmentioning

confidence: 99%

The Mammalian Exocyst, a Complex Required for Exocytosis, Inhibits Tubulin Polymerization

Wang

Liu

Adamson

et al. 2004

Journal of Biological Chemistry

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“…Furthermore, it was shown that Rho3 binds to Exo70 in its GTP-bound form (Robinson et al 1999). However, Exo70 mutants that are deficient in Rho3 binding have no defect in exocytosis (He et al 2007a;Hutagalung et al 2009).…”

Section: The Rho Family Of Small Gtp-binding Proteinsmentioning

confidence: 99%

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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“…Its vector portion was replaced with pRS426 to create MGal-p50-Q24. The expected amino acid sequences of the polyglutamines expressed in this study are as follows: 3HA-Q34, MYPYDVPDYAGYPYDVPDYAGYPYDVPDYAGTQQQK(Q) 31 RDPAS; 3HA-Q80, MYPYDVPDYAGYPYDVPDYAGYPYDVPDYAGTQQ-QK(Q) 77 RDPAS; P50-Q24, MDPYLGRPEQMFHLDGTEKQQQ-K(Q) 21 RDPAS; p50-Q34, MDPYLGRPEQMFHLDGTEKQQQK (Q) 31 RDPAS; and p50-Q80, MDPYLGRPEQMFHLDGTEKQQ-QK(Q) 77 RDPAS. Underlined sequences are epitope tag sequences for anti-p50 antibody.…”

Section: Methodsmentioning

confidence: 98%

“…Cell Staining and Microscopic Analysis-Immunofluorescence of yeast cells was examined using standard procedures (21). Briefly, 0.1 M KPO 4 (pH 6.5) was added to the culture, and then cells (2 ϫ 10 7 ) were fixed with 3.6% formaldehyde.…”

Section: Methodsmentioning

confidence: 99%

Circumvention of Chaperone Requirement for Aggregate Formation of a Short Polyglutamine Tract by the Co-expression of a Long Polyglutamine Tract

Kimura

Koitabashi

Kakizuka

et al. 2002

Journal of Biological Chemistry

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Polyglutamine disease is now recognized as one of the conformational, amyloid-related diseases. In this disease, polyglutamine expansion in proteins has toxic effects on cells and also results in the formation of aggregates. Polyglutamine aggregate formation is accompanied by conversion of the polyglutamine from a soluble to an insoluble form. In yeast, the efficiency of the aggregate formation is determined by the balance of various parameters, including the length of the polyglutamine tract, the function of Hsp104, and the level of polyglutamine expression. In this study, we found that the co-expression of a long polyglutamine tract, which formed aggregates independently of the function of Hsp104, enhanced the formation of aggregates of a short polyglutamine tract in wild-type cells as well as in ⌬hsp104 mutant cells. Thus, the expression of a long polyglutamine tract would be an additional parameter determining the efficiency of aggregate formation of a short polyglutamine tract. The co-localization of aggregates of long and short polyglutamine tracts suggests the possibility that the enhancement occurs due to the seeding of aggregates of the long polyglutamine tracts.Expansion of polyglutamine repeats in a protein has now been proved to account for the pathogenesis of at least nine inherited neurodegenerative diseases, including spinobulbar muscular atrophy, Huntington's disease, spinocerebellar ataxia types 1, 2, 3, 6, 7, and 17 (SCA1, SCA2, SCA3/MJD, SCA6, SCA7, and SCA17, respectively), and dentatorubural pallidoluysian atrophy (1-4). The expression of polyglutamine repeats is sufficient to cause neurodegeneration or toxicity in model organisms and cell death in cultured cells (5-11). The clinical severity and the age of onset of disease symptoms are mainly determined by the length of the polyglutamine in the protein responsible, that is, the longer the polyglutamine, the earlier the onset, and the more severe the disease. Moreover, the deposition of aggregates that contain the expanded polyglutamine is a hallmark of the affected organs and dying cells, and the ability of the expanded polyglutamine to induce these toxic phenomena appears to be inseparably linked with its ability to form aggregates. Thus, the conformational change of the expanded polyglutamine is likely a pathogenic mechanism causing these diseases, although whether the aggregates themselves are pathogenic or not is unknown. Moreover, staining of the brain of Huntington's disease patients with Congo Red suggests that polyglutamine diseases are associated with amyloid fibrils (12).Polyglutamine aggregate formation of amyloid-like appearance has been observed in vitro (13-15). These studies indicate that aggregate formation is autonomous in vitro in the length-, concentration-, and time-dependent manner of a polyglutamine. However, in vivo, in yeast, polyglutamine aggregate formation requires the function of the molecular chaperone Hsp104, a member of the AAA ϩ superfamily, in addition to the parameters noted above (16,17). Upon induction of...

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Rho3 of Saccharomyces cerevisiae, Which Regulates the Actin Cytoskeleton and Exocytosis, Is a GTPase Which Interacts with Myo2 and Exo70

Abstract: E129,A131 , which causes a morphological abnormality, was expressed. These results provide a direct molecular basis for the action of Rho3 on exocytosis and the actin cytoskeleton.

Cited by 188 publications

References 63 publications

The Mammalian Exocyst, a Complex Required for Exocytosis, Inhibits Tubulin Polymerization

The Mammalian Exocyst, a Complex Required for Exocytosis, Inhibits Tubulin Polymerization

Membrane Organization and Dynamics in Cell Polarity

Circumvention of Chaperone Requirement for Aggregate Formation of a Short Polyglutamine Tract by the Co-expression of a Long Polyglutamine Tract

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