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Hummel DR, Kaksonen M. Spatio-temporal regulation of endocytic protein assembly by SH3 domains in yeast. Mol Biol Cell 2023; 34:ar19. [PMID: 36696224 PMCID: PMC10011730 DOI: 10.1091/mbc.e22-09-0406] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Clathrin-mediated endocytosis is a conserved eukaryotic membrane trafficking pathway that is driven by a sequentially assembled molecular machinery that contains over 60 different proteins. SH3 domains are the most abundant protein-protein interaction domain in this process, but the function of most SH3 domains in protein dynamics remains elusive. Using mutagenesis and live-cell fluorescence microscopy in the budding yeast Saccharomyces cerevisiae, we dissected SH3-mediated regulation of the endocytic pathway. Our data suggest that multiple SH3 domains regulate the actin nucleation-promoting Las17-Vrp1 complex, and that the network of SH3 interactions coordinates both Las17-Vrp1 assembly and dissociation. Furthermore, most endocytic SH3 domain proteins use the SH3 domain for their own recruitment, while a minority use the SH3 domain to recruit other proteins and not themselves. Our results provide a dynamic map of SH3 functions in yeast endocytosis and a framework for SH3 interaction network studies across biology.
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Affiliation(s)
- Daniel R Hummel
- Department of Biochemistry, University of Geneva, Department of Biochemistry, 1205 Genève, Switzerland
| | - Marko Kaksonen
- Department of Biochemistry, University of Geneva, Department of Biochemistry, 1205 Genève, Switzerland
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2
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Yeast as a Model to Understand Actin-Mediated Cellular Functions in Mammals-Illustrated with Four Actin Cytoskeleton Proteins. Cells 2020; 9:cells9030672. [PMID: 32164332 PMCID: PMC7140605 DOI: 10.3390/cells9030672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/05/2020] [Accepted: 03/05/2020] [Indexed: 12/31/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae has an actin cytoskeleton that comprises a set of protein components analogous to those found in the actin cytoskeletons of higher eukaryotes. Furthermore, the actin cytoskeletons of S. cerevisiae and of higher eukaryotes have some similar physiological roles. The genetic tractability of budding yeast and the availability of a stable haploid cell type facilitates the application of molecular genetic approaches to assign functions to the various actin cytoskeleton components. This has provided information that is in general complementary to that provided by studies of the equivalent proteins of higher eukaryotes and hence has enabled a more complete view of the role of these proteins. Several human functional homologues of yeast actin effectors are implicated in diseases. A better understanding of the molecular mechanisms underpinning the functions of these proteins is critical to develop improved therapeutic strategies. In this article we chose as examples four evolutionarily conserved proteins that associate with the actin cytoskeleton: (1) yeast Hof1p/mammalian PSTPIP1, (2) yeast Rvs167p/mammalian BIN1, (3) yeast eEF1A/eEF1A1 and eEF1A2 and (4) yeast Yih1p/mammalian IMPACT. We compare the knowledge on the functions of these actin cytoskeleton-associated proteins that has arisen from studies of their homologues in yeast with information that has been obtained from in vivo studies using live animals or in vitro studies using cultured animal cell lines.
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3
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Prigent M, Chaillot J, Tisserand H, Boy-Marcotte E, Cuif MH. Three members of the yeast N-BAR proteins family form heterogeneous lattices in vivo and interact differentially with two RabGAP proteins. Sci Rep 2020; 10:1698. [PMID: 32015451 PMCID: PMC6997364 DOI: 10.1038/s41598-020-58606-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 01/08/2020] [Indexed: 11/26/2022] Open
Abstract
The yeast N-BAR (Bin/Amphiphysin/Rvs167) protein Rvs167 is recruited by the Rab GTPase Activating Proteins (RabGAP) Gyp5 and Gyl1 to the tip of small buds to act in exocytosis. Investigating other N-BAR proteins involved in Gyp5/Gyl1/Rvs167 complexes, we found that Rvs161, an Rvs167 paralog, is absent from the complexes formed at the tip of small buds. Immunoprecipitation and Bimolecular Fluorescence Complementation (BiFC) analysis show that both Rvs167 and Rvs161 interact in vivo with Gvp36, an N-BAR protein. Rvs167 molecules also interact independently of Rvs161 and Gvp36. Rvs167/Rvs167 and Rvs167/Gyp5 interactions predominate over other combinations at the tip of small buds, suggesting that N-BAR lattices enriched in Rvs167 molecules form at these sites. By combining BiFC with markers specific to each organelle, we analyzed systematically in living cells the locations of the BiFC signals generated by combinations of the three N-BAR proteins. We show that the BiFC signals differ according to organelle and cell site, strongly suggesting heterogeneity in the composition of N-BAR protein lattices in vivo. Our results reveal that the organization of N-BAR protein lattices in vivo is complex and are consistent with N-BAR proteins forming various types of dimers and lattices of variable composition.
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Affiliation(s)
- Magali Prigent
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Julien Chaillot
- Institut sur la Nutrition et les Aliments Fonctionnels (INAF), Université Laval, 2440 Boulevard Hochelaga, Québec, QC, G1V 0A6, Canada
| | - Hélène Tisserand
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Emmanuelle Boy-Marcotte
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Marie-Hélène Cuif
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
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4
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Jiang L, Ge W, Geng J. miR-425 regulates cell proliferation, migration and apoptosis by targeting AMPH-1 in non-small-cell lung cancer. Pathol Res Pract 2019; 215:152705. [PMID: 31685299 DOI: 10.1016/j.prp.2019.152705] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/10/2019] [Accepted: 10/19/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND MicroRNAs (miRNAs) have been proved to act as vital roles on non-small-cell lung cancer (NSCLC), and miR-425 has been proven to serve an important function in several tumors. However, the functional role of miR-425 on NSCLC is still unclear. METHODS The mRNA and protein expression of miR-425 and AMPH-1 were determined by qRT-PCR and western blot analysis, respectively. NSCLC cells (SK-MES-1 and A549) proliferation and migration were measured by CCK-8 and transwell assay, respectively. Cell apoptosis was assessed by flow cytometry and western blotting, In addition, luciferase reporter assay was carried out to confirm the direct targeting of AMPH-1 by miR-425. Xenograft experiments were performed to observe the tumorigenesis of miR-425 in vivo. RESULTS The results showed that miR-425 was overexpressed and AMPH-1 expression was downregulated in SK-MES-1 and A549 cells. Silencing miR-425 inhibited proliferation, migration and promoted apoptosis of NSCLC cells. Moreover, we proved that miR-425 could target AMPH-1. The expression of AMPH-1was upregulated in A549 with miR-425 inhibitor. Moreover, miR-425 knockdown were less tumorigenic than the control in vivo. CONCLUSIONS Taken together, miR-425 could promote the proliferation, invasion and suppress apoptosis by targeting AMPH-1 in NSCLC cells. miR-425/AMPH-1 axis may represent a potential therapeutic strategy or novel prognostic biomarkers to NSCLC.
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Affiliation(s)
- Lei Jiang
- Department of Pathology, Harbin Medical University Cancer Hospital, Harbin 150040, China
| | - Wenyu Ge
- Department of Stomatology, Hospital of Heilongjiang Province, Harbin 150036, China
| | - Jingshu Geng
- Department of Pathology, Harbin Medical University Cancer Hospital, Harbin 150040, China.
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5
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Simunovic M, Evergren E, Callan-Jones A, Bassereau P. Curving Cells Inside and Out: Roles of BAR Domain Proteins in Membrane Shaping and Its Cellular Implications. Annu Rev Cell Dev Biol 2019; 35:111-129. [DOI: 10.1146/annurev-cellbio-100617-060558] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many cellular processes rely on precise and timely deformation of the cell membrane. While many proteins participate in membrane reshaping and scission, usually in highly specialized ways, Bin/amphiphysin/Rvs (BAR) domain proteins play a pervasive role, as they not only participate in many aspects of cell trafficking but also are highly versatile membrane remodelers. Subtle changes in the shape and size of the BAR domain can greatly impact the way in which BAR domain proteins interact with the membrane. Furthermore, the activity of BAR domain proteins can be tuned by external physical parameters, and so they behave differently depending on protein surface density, membrane tension, or membrane shape. These proteins can form 3D structures that mold the membrane and alter its liquid properties, even promoting scission under various circumstances.As such, BAR domain proteins have numerous roles within the cell. Endocytosis is among the most highly studied processes in which BAR domain proteins take on important roles. Over the years, a more complete picture has emerged in which BAR domain proteins are tied to almost all intracellular compartments; examples include endosomal sorting and tubular networks in the endoplasmic reticulum and T-tubules. These proteins also have a role in autophagy, and their activity has been linked with cancer. Here, we briefly review the history of BAR domain protein discovery, discuss the mechanisms by which BAR domain proteins induce curvature, and attempt to settle important controversies in the field. Finally, we review BAR domain proteins in the context of a cell, highlighting their emerging roles in cell signaling and organelle shaping.
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Affiliation(s)
- Mijo Simunovic
- Center for Studies in Physics and Biology, The Rockefeller University, New York, NY 10065, USA
| | - Emma Evergren
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast BT9 7BL, United Kingdom
| | - Andrew Callan-Jones
- Laboratoire Matière et Systèmes Complexes, CNRS UMR 7057, 75205 Paris, France
| | - Patricia Bassereau
- Laboratoire Physico Chimie Curie, CNRS UMR 168, Institut Curie, PSL Research University, 75005 Paris, France
- Sorbonne Université, 75005 Paris, France
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6
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Bairwa G, Caza M, Horianopoulos L, Hu G, Kronstad J. Role of clathrin-mediated endocytosis in the use of heme and hemoglobin by the fungal pathogen Cryptococcus neoformans. Cell Microbiol 2018; 21:e12961. [PMID: 30291809 DOI: 10.1111/cmi.12961] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/23/2018] [Accepted: 09/17/2018] [Indexed: 12/29/2022]
Abstract
Heme is a major source of iron for pathogens of humans, and its use is critical in determining the outcome of infection and disease. Cryptococcus neoformans is an encapsulated fungal pathogen that causes life-threatening infections in immunocompromised individuals. C. neoformans effectively uses heme as an iron source, but the underlying mechanisms are poorly defined. Non-iron metalloporphyrins (MPPs) are toxic analogues of heme and are thought to enter microbial cells via endogenous heme acquisition systems. We therefore carried out a mutant screen for susceptibility against manganese MPP (MnMPP) to identify new components for heme uptake in C. neoformans. We identified several genes involved in signalling, DNA repair, sugar metabolism, and trafficking that play important roles in susceptibility to MnMPP and in the use of heme as an iron source. We focused on investigating the role of clathrin-mediated endocytosis (CME) and found that several components of CME including Chc1, Las17, Rvs161, and Rvs167 are required for growth on heme and hemoglobin and for endocytosis and intracellular trafficking of these molecules. We show that the hemoglobin uptake process in C. neoformans involves clathrin heavy chain, Chc1, which appears to colocalise with hemoglobin-containing vesicles and to potentially assist in proper delivery of hemoglobin to the vacuole. Additionally, C. neoformans strains lacking Chc1, Las17, Rvs161, or Rvs167 were defective in the elaboration of several key virulence factors, and a las17 mutant was avirulent in a mouse model of cryptococcosis. Overall, this study unveils crucial functions of CME in the use of heme iron by C. neoformans and reveals a role for CME in fungal pathogenesis.
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Affiliation(s)
- Gaurav Bairwa
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - Mélissa Caza
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - Linda Horianopoulos
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.,Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Guanggan Hu
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - James Kronstad
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.,Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
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7
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Yang H, Wan Z, Huang C, Yin H, Song D. AMPH-1 is a tumor suppressor of lung cancer by inhibiting Ras-Raf-MEK-ERK signal pathway. Lasers Med Sci 2018; 34:473-478. [PMID: 30143925 DOI: 10.1007/s10103-018-2616-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/13/2018] [Indexed: 11/27/2022]
Abstract
Amphiphysin 1 (AMPH-1) is a nerve terminal-enriched protein and it is a 128-kD protein with three identified functional domains. Some studies found that AMPH-1 was a dominant autoantigen associated with breast cancer and melanoma. However, its function in lung cancer is unknown. Here, we showed that AMPH-1 knockdown dramatically increased cell proliferation, attenuated cell apoptosis, and promoted cell cycle progression in human lung cancer cells. In vivo xenograft studies confirmed that the AMPH-1-knockdown cells were more tumorigenic than the controls. Moreover, we demonstrated that silencing AMPH-1 markedly activated Ras-Raf-MEK-ERK signal pathway. In summary, our results identified the anti-oncogenic function of AMPH-1 in lung cancer in vitro and in vivo. It is proposed that AMPH-1 may have potential as a new therapeutic target in human lung cancer treatment.
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Affiliation(s)
- Haifeng Yang
- Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, 225300, Jiangsu Province, People's Republic of China.
| | - Zhenzhou Wan
- Medical Laboratory of Taizhou Fourth People's Hospital, Taizhou, Jiangsu, China
| | - Cheng Huang
- Jiangsu Agri-Animal Husbandry Vocational College, Taizhou, 225300, Jiangsu Province, People's Republic of China
| | - Huabin Yin
- Department of Orthopedics, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, 100 Haining Road, 200080, Shanghai, People's Republic of China
| | - Dianwen Song
- Department of Orthopedics, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, 100 Haining Road, 200080, Shanghai, People's Republic of China
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8
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Myers MD, Ryazantsev S, Hicke L, Payne GS. Calmodulin Promotes N-BAR Domain-Mediated Membrane Constriction and Endocytosis. Dev Cell 2016; 37:162-73. [PMID: 27093085 DOI: 10.1016/j.devcel.2016.03.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 02/15/2016] [Accepted: 03/16/2016] [Indexed: 10/21/2022]
Abstract
Membrane remodeling by BAR (Bin, Amphiphysin, RVS) domain-containing proteins, such as endophilins and amphiphysins, is integral to the process of endocytosis. However, little is known about the regulation of endocytic BAR domain activity. We have identified an interaction between the yeast Rvs167 N-BAR domain and calmodulin. Calmodulin-binding mutants of Rvs167 exhibited defects in endocytic vesicle release. In vitro, calmodulin enhanced membrane tubulation and constriction by wild-type Rvs167 but not calmodulin-binding-defective mutants. A subset of mammalian N-BAR domains bound calmodulin, and co-expression of calmodulin with endophilin A2 potentiated tubulation in vivo. These studies reveal a conserved role for calmodulin in regulating the intrinsic membrane-sculpting activity of endocytic N-BAR domains.
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Affiliation(s)
- Margaret D Myers
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Sergey Ryazantsev
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Linda Hicke
- Molecular Genetics and Microbiology, College of Natural Sciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Gregory S Payne
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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9
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Toume M, Tani M. Yeast lacking the amphiphysin family protein Rvs167 is sensitive to disruptions in sphingolipid levels. FEBS J 2016; 283:2911-28. [PMID: 27312128 DOI: 10.1111/febs.13783] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/23/2016] [Accepted: 06/15/2016] [Indexed: 12/13/2022]
Abstract
Rvs167 and Rvs161 in Saccharomyces cerevisiae are amphiphysin family proteins, which are involved in several important cellular events, such as invagination and scission of endocytic vesicles, and actin cytoskeleton organization. It has been reported that cellular dysfunctions caused by deletion of RVS167 or RVS161 are rescued by deletion of specific nonessential sphingolipid-metabolizing enzyme genes. Here, we found that yeast cells lacking RVS167 or RVS161 exhibit a decrease in sphingolipid levels. In rvs167∆ cells, the expression level of Orm2, a negative regulator of serine palmitoyltransferase (SPT) catalyzing the initial step of sphingolipid biosynthesis, was increased in a calcineurin-dependent manner, and the decrease in sphingolipid levels in rvs167∆ cells was reversed on deletion of ORM2. Moreover, repression of both ORM1 and ORM2 expression or overexpression of SPT caused a strong growth defect of rvs167∆ cells, indicating that enhancement of de novo sphingolipid biosynthesis is detrimental to rvs167∆ cells. In contrast, partial repression of LCB1-encoding SPT suppressed abnormal phenotypes caused by the deletion of RVS167, including supersensitivity to high temperature and salt stress, and impairment of endocytosis and actin cytoskeleton organization. In addition, the partial repression of SPT activity suppressed the temperature supersensitivity and abnormal vacuolar morphology caused by deletion of VPS1 encoding a dynamin-like GTPase, which is required for vesicle scission and is functionally closely related to Rvs167/Rvs161, whereas repression of both ORM1 and ORM2 expression in vps1∆ cells caused a growth defect. Thus, it was suggested that proper regulation of SPT activity is indispensable for amphiphysin-deficient cells.
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Affiliation(s)
- Moeko Toume
- Department of Chemistry, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Motohiro Tani
- Department of Chemistry, Faculty of Sciences, Kyushu University, Fukuoka, Japan
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10
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Guiney EL, Goldman AR, Elias JE, Cyert MS. Calcineurin regulates the yeast synaptojanin Inp53/Sjl3 during membrane stress. Mol Biol Cell 2015; 26:769-85. [PMID: 25518934 PMCID: PMC4325846 DOI: 10.1091/mbc.e14-05-1019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 12/04/2014] [Accepted: 12/11/2014] [Indexed: 11/12/2022] Open
Abstract
During hyperosmotic shock, Saccharomyces cerevisiae adjusts to physiological challenges, including large plasma membrane invaginations generated by rapid cell shrinkage. Calcineurin, the Ca(2+)/calmodulin-dependent phosphatase, is normally cytosolic but concentrates in puncta and at sites of polarized growth during intense osmotic stress; inhibition of calcineurin-activated gene expression suggests that restricting its access to substrates tunes calcineurin signaling specificity. Hyperosmotic shock promotes calcineurin binding to and dephosphorylation of the PI(4,5)P2 phosphatase synaptojanin/Inp53/Sjl3 and causes dramatic calcineurin-dependent reorganization of PI(4,5)P2-enriched membrane domains. Inp53 normally promotes sorting at the trans-Golgi network but localizes to cortical actin patches in osmotically stressed cells. By activating Inp53, calcineurin repolarizes the actin cytoskeleton and maintains normal plasma membrane morphology in synaptojanin-limited cells. In response to hyperosmotic shock and calcineurin-dependent regulation, Inp53 shifts from associating predominantly with clathrin to interacting with endocytic proteins Sla1, Bzz1, and Bsp1, suggesting that Inp53 mediates stress-specific endocytic events. This response has physiological and molecular similarities to calcineurin-regulated activity-dependent bulk endocytosis in neurons, which retrieves a bolus of plasma membrane deposited by synaptic vesicle fusion. We propose that activation of Ca(2+)/calcineurin and PI(4,5)P2 signaling to regulate endocytosis is a fundamental and conserved response to excess membrane in eukaryotic cells.
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Affiliation(s)
- Evan L Guiney
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Aaron R Goldman
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Joshua E Elias
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305
| | - Martha S Cyert
- Department of Biology, Stanford University, Stanford, CA 94305
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11
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Cundell MJ, Price C. The budding yeast amphiphysin complex is required for contractile actin ring (CAR) assembly and post-contraction GEF-independent accumulation of Rho1-GTP. PLoS One 2014; 9:e97663. [PMID: 24874185 PMCID: PMC4038553 DOI: 10.1371/journal.pone.0097663] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 04/22/2014] [Indexed: 12/26/2022] Open
Abstract
The late events of the budding yeast cell division cycle, cytokinesis and cell separation, require the assembly of a contractile actomyosin ring (CAR), primary and secondary septum formation followed by enzymatic degradation of the primary septum. Here we present evidence that demonstrates a role for the budding yeast amphiphysin complex, a heterodimer comprising Rvs167 and Rvs161, in CAR assembly and cell separation. The iqg1-1 allele is synthetically lethal with both rvs167 and rvs161 null mutations. We show that both Iqg1 and the amphiphysin complex are required for CAR assembly in early anaphase but cells are able to complete assembly in late anaphase when these activities are, respectively, either compromised or absent. Amphiphysin dependent CAR assembly is dependent upon the Rvs167 SH3 domain, but this function is insufficient to explain the observed synthetic lethality. Dosage suppression of the iqg1-1 allele demonstrates that endocytosis is required for the default cell separation pathway in the absence of CAR contraction but is unlikely to be required to maintain viability. The amphiphysin complex is required for normal, post-mitotic, localization of Chs3 and the Rho1 GEF, Rom2, which are responsible for secondary septum deposition and the accumulation of GTP bound Rho1 at the bud neck. It is concluded that a failure of polarity establishment in the absence of CAR contraction and amphiphysin function leads to loss of viability as a result of the consequent cell separation defect.
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Affiliation(s)
- Michael John Cundell
- School of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
| | - Clive Price
- School of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
- * E-mail:
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12
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Amphiphysin 2 (BIN1) in physiology and diseases. J Mol Med (Berl) 2014; 92:453-63. [DOI: 10.1007/s00109-014-1138-1] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 02/11/2014] [Accepted: 02/17/2014] [Indexed: 12/15/2022]
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13
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Tuo S, Nakashima K, Pringle JR. Role of endocytosis in localization and maintenance of the spatial markers for bud-site selection in yeast. PLoS One 2013; 8:e72123. [PMID: 24039741 PMCID: PMC3764181 DOI: 10.1371/journal.pone.0072123] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 07/06/2013] [Indexed: 11/19/2022] Open
Abstract
The yeast Saccharomyces cerevisiae normally selects bud sites (and hence axes of cell polarization) in one of two distinct patterns, the axial pattern of haploid cells and the bipolar pattern of diploid cells. These patterns depend on distinct sets of cortical-marker proteins that transmit positional information through a common signaling pathway based on a Ras-type GTPase. It has been reported previously that various proteins of the endocytic pathway may be involved in determining the bipolar pattern but not the axial pattern. To explore this question systematically, we constructed and analyzed congenic haploid and diploid deletion mutants for 14 genes encoding proteins that are involved in endocytosis. The mutants displayed a wide range of severities in their overall endocytosis defects, as judged by their growth rates and abilities to take up the lipophilic dye FM 4-64. Consistent with the previous reports, none of the mutants displayed a significant defect in axial budding, but they displayed defects in bipolar budding that were roughly correlated with the severities of their overall endocytosis defects. Both the details of the mutant budding patterns and direct examination of GFP-tagged marker proteins suggested that both initial formation and maintenance of the normally persistent bipolar marks depend on endocytosis, as well as polarized exocytosis, in actively growing cells. Interestingly, maintenance of the bipolar marks in non-growing cells did not appear to require normal levels of endocytosis. In some cases, there was a striking lack of correlation between the overall severities of the general-endocytosis defect and the bud-site selection defect, suggesting that various endocytosis proteins may differ in their importance for the uptake of various plasma-membrane targets.
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Affiliation(s)
- Shanshan Tuo
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Kenichi Nakashima
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - John R. Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
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14
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Hof1 and Rvs167 have redundant roles in actomyosin ring function during cytokinesis in budding yeast. PLoS One 2013; 8:e57846. [PMID: 23469085 PMCID: PMC3585203 DOI: 10.1371/journal.pone.0057846] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 01/28/2013] [Indexed: 11/19/2022] Open
Abstract
The Hof1 protein (Homologue of Fifteen) regulates formation of the primary septum during cytokinesis in the budding yeast Saccharomyces cerevisiae, whereas the orthologous Cdc15 protein in fission yeast regulates the actomyosin ring by using its F-BAR domain to recruit actin nucleators to the cleavage site. Here we show that budding yeast Hof1 also contributes to actin ring assembly in parallel with the Rvs167 protein. Simultaneous deletion of the HOF1 and RVS167 genes is lethal, and cells fail to assemble the actomyosin ring as they progress through mitosis. Although Hof1 and Rvs167 are not orthologues, they both share an analogous structure, with an F-BAR or BAR domain at the amino terminus, capable of inducing membrane curvature, and SH3 domains at the carboxyl terminus that bind to specific proline-rich targets. The SH3 domain of Rvs167 becomes essential for assembly of the actomyosin ring in cells lacking Hof1, suggesting that it helps to recruit a regulator of the actin cytoskeleton. This new function of Rvs167 appears to be independent of its known role as a regulator of the Arp2/3 actin nucleator, as actin ring assembly is not abolished by the simultaneous inactivation of Hof1 and Arp2/3. Instead we find that recruitment to the bud-neck of the Iqg1 actin regulator is defective in cells lacking Hof1 and Rvs167, though future studies will be needed to determine if this reflects a direct interaction between these factors. The redundant role of Hof1 in actin ring assembly suggests that the mechanism of actin ring assembly has been conserved to a greater extent across evolution than anticipated previously.
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15
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Prigent M, Boy-Marcotte E, Chesneau L, Gibson K, Dupré-Crochet S, Tisserand H, Verbavatz JM, Cuif MH. The RabGAP proteins Gyp5p and Gyl1p recruit the BAR domain protein Rvs167p for polarized exocytosis. Traffic 2011; 12:1084-97. [PMID: 21554509 DOI: 10.1111/j.1600-0854.2011.01218.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Rab GTPase-activating proteins (GAP) Gyp5p and Gyl1p are involved in the control of polarized exocytosis at the small-bud stage in Saccharomyces cerevisiae. Both Gyp5p and Gyl1p interact with the N-Bin1/Amphiphysin/Rvs167 (BAR) domain protein Rvs167p, but the biological function of this interaction is unclear. We show here that Gyp5p and Gyl1p recruit Rvs167p to the small-bud tip, where it plays a role in polarized exocytosis. In gyp5Δgyl1Δ cells, Rvs167p is not correctly localized to the small-bud tip. Both P473L mutation in the SH3 domain of Rvs167p and deletion of the proline-rich regions of Gyp5p and Gyl1p disrupt the interaction of Rvs167p with Gyp5p and Gyl1p and impair the localization of Rvs167p to the tips of small buds. We provide evidence for the accumulation of secretory vesicles in small buds of rvs167Δ cells and for defective Bgl2p secretion in rvs167Δ cultures enriched in small-budded cells at 13°C, implicating Rvs167p in polarized exocytosis. Moreover, both the accumulation of secretory vesicles in Rvs167p P473L cells cultured at 13°C and secretion defects in cells producing Gyp5p and Gyl1p without proline-rich regions strongly suggest that the function of Rvs167p in exocytosis depends on its ability to interact with Gyp5p and Gyl1p.
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Affiliation(s)
- Magali Prigent
- Univ Paris-Sud, Institut de Génétique et Microbiologie, CNRS UMR8621, Bâtiment 400, Orsay F-91405, France
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16
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Youn JY, Friesen H, Kishimoto T, Henne WM, Kurat CF, Ye W, Ceccarelli DF, Sicheri F, Kohlwein SD, McMahon HT, Andrews BJ. Dissecting BAR domain function in the yeast Amphiphysins Rvs161 and Rvs167 during endocytosis. Mol Biol Cell 2010; 21:3054-69. [PMID: 20610658 PMCID: PMC2929998 DOI: 10.1091/mbc.e10-03-0181] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 06/25/2010] [Accepted: 06/29/2010] [Indexed: 02/05/2023] Open
Abstract
BAR domains are protein modules that bind to membranes and promote membrane curvature. One type of BAR domain, the N-BAR domain, contains an additional N-terminal amphipathic helix, which contributes to membrane-binding and bending activities. The only known N-BAR-domain proteins in the budding yeast Saccharomyces cerevisiae, Rvs161 and Rvs167, are required for endocytosis. We have explored the mechanism of N-BAR-domain function in the endocytosis process using a combined biochemical and genetic approach. We show that the purified Rvs161-Rvs167 complex binds to liposomes in a curvature-independent manner and promotes tubule formation in vitro. Consistent with the known role of BAR domain polymerization in membrane bending, we found that Rvs167 BAR domains interact with each other at cortical actin patches in vivo. To characterize N-BAR-domain function in endocytosis, we constructed yeast strains harboring changes in conserved residues in the Rvs161 and Rvs167 N-BAR domains. In vivo analysis of the rvs endocytosis mutants suggests that Rvs proteins are initially recruited to sites of endocytosis through their membrane-binding ability. We show that inappropriate regulation of complex sphingolipid and phosphoinositide levels in the membrane can impinge on Rvs function, highlighting the relationship between membrane components and N-BAR-domain proteins in vivo.
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Affiliation(s)
- Ji-Young Youn
- Department of Molecular Genetics, Banting and Best Department of Medical Research, Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S3E1, Canada
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17
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Guillou H, Zadravec D, Martin PGP, Jacobsson A. The key roles of elongases and desaturases in mammalian fatty acid metabolism: Insights from transgenic mice. Prog Lipid Res 2009; 49:186-99. [PMID: 20018209 DOI: 10.1016/j.plipres.2009.12.002] [Citation(s) in RCA: 569] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 12/09/2009] [Accepted: 12/10/2009] [Indexed: 12/31/2022]
Abstract
In mammalian cells, elongases and desaturases play critical roles in regulating the length and degree of unsaturation of fatty acids and thereby their functions and metabolic fates. In the past decade, a great deal has been learnt about these enzymes and the first part of this review summarizes our current knowledge concerning these enzymes. More recently, several transgenic mouse models lacking either an elongase (Elovl3(-/-), Elovl4(-/-), Elovl5(-/-), Elovl6(-/-)) or a desaturase (Scd-1(-/-), Scd-2(-/-), Fads2(-/-)) have been developed and the second part of this review focuses on the insights gained from studies with these mice, as well as from investigations on cell cultures.
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Affiliation(s)
- Hervé Guillou
- Integrative Toxicology and Metabolism, Pôle de Toxicologie Alimentaire, Laboratoire de Pharmacologie et Toxicologie, Institut National de la Recherche Agronomique INRA UR66, Toulouse Cedex 3, France
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18
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Zhong X, Hoelz DJ, Kumar HR, Sandoval JA, Rescorla FJ, Hickey RJ, Malkas LH. Bin1 is linked to metastatic potential and chemosensitivity in neuroblastoma. Pediatr Blood Cancer 2009; 53:332-7. [PMID: 19418541 DOI: 10.1002/pbc.22068] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Neuroblastoma (NB) is the most common extracranial solid tumor in children. At the time of diagnosis, the tumor has metastasized in as many as 7 of 10 cases, and survival in high-risk patients remains poor. Accurate classification of high-risk patients is very important since this determines treatment plan, and although a consensus risk classification system has been established for NB, it contains few specific molecular markers that account for aggressive nature and metastatic potential of the tumor. Bin1 expression is reduced in breast, NB, and other cancer types and the reduction correlates with high-risk clinical features. Here we hypothesize that Bin1 has an inhibitory role in metastasis, and therefore decrease in its expression may be a marker of high-risk NB. PROCEDURE Initially, breast cancer and NB cell lines derived from metastasis were examined for Bin1 expression. Then, a stable Bin1-overexpressing NB cell line was created and evaluated for in vitro metastatic behaviors using anoikis, invasion, and migration assays, and chemoresponsiveness using MTT assay. RESULTS Reduced Bin1 was detected in all cancer cell lines examined, and forced Bin1 overexpression increased NB cell anoikis and enhanced the cell killing by doxorubicin. However, Bin1 overexpression did not significantly affect cell invasion, motility, or proliferation. CONCLUSIONS Bin1 appears to function as a metastasis suppressor and chemosensitizer in NB, and resistance to anoikis may be an important metastatic mechanism. Thus, Bin1 expression status could serve as a marker for metastatic potential and chemosensitivity thereby allowing for more accurate classifications of high-risk NB patients.
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Affiliation(s)
- Xiaoling Zhong
- Department of Surgery, Section of Pediatric Surgery, Riley Children's Hospital, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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19
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Tran N, Qu PP, Simpson DA, Lindsey-Boltz L, Guan X, Schmitt CP, Ibrahim JG, Kaufmann WK. In silico construction of a protein interaction landscape for nucleotide excision repair. Cell Biochem Biophys 2009; 53:101-14. [PMID: 19156361 DOI: 10.1007/s12013-009-9042-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To obtain a systems-level perspective on the topological and functional relationships among proteins contributing to nucleotide excision repair (NER) in Saccharomyces cerevisiae, we built two models to analyze protein-protein physical interactions. A recursive computational model based on set theory systematically computed overlaps among protein interaction neighborhoods. A statistical model scored computation results to detect significant overlaps which exposed protein modules and hubs concurrently. We used these protein entities to guide the construction of a multi-resolution landscape which showed relationships among NER, transcription, DNA replication, chromatin remodeling, and cell cycle regulation. Literature curation was used to support the biological significance of identified modules and hubs. The NER landscape revealed a hierarchical topology and a recurrent pattern of kernel modules coupling a variety of proteins in structures that provide diverse functions. Our analysis offers a computational framework that can be applied to construct landscapes for other biological processes.
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Affiliation(s)
- Nancy Tran
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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20
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Prendergast GC, Muller AJ, Ramalingam A, Chang MY. BAR the door: cancer suppression by amphiphysin-like genes. Biochim Biophys Acta Rev Cancer 2008; 1795:25-36. [PMID: 18930786 DOI: 10.1016/j.bbcan.2008.09.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 08/26/2008] [Accepted: 09/03/2008] [Indexed: 11/17/2022]
Abstract
The evolutionarily conserved amphiphysin-like genes Bin1 and Bin3 function in membrane and actin dynamics, cell polarity, and stress signaling. Recent genetic studies in mice discriminate non-essential roles in endocytic processes commonly ascribed to amphiphysins from essential roles in cancer suppression. Bin1 acts in default pathways of apoptosis and senescence that are triggered by the Myc and Raf oncogenes in primary cells, and Bin1 gene products display a 'moonlighting function' in the nucleus where a variety of other 'endocytic' proteins are also found. Together, genetic investigations in yeast, flies, and mice suggest that amphiphysin-like adapter proteins may suppress cancer by helping integrate cell polarity signals generated by actin and vesicle dynamics with central regulators of cell cycle arrest, apoptosis, and immune surveillance.
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21
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Kinney EL, Tanida S, Rodrigue AA, Johnson JK, Tompkins VS, Sakamuro D. Adenovirus E1A oncoprotein liberates c-Myc activity to promote cell proliferation through abating Bin1 expression via an Rb/E2F1-dependent mechanism. J Cell Physiol 2008; 216:621-31. [PMID: 18348166 DOI: 10.1002/jcp.21437] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Adenovirus E1A oncogene transforms primary rodent fibroblasts in cooperation with activated Ras. Conversely, the c-Myc oncoprotein-binding tumor suppressor, Bin1, inhibits Ras/E1A-mediated cell transformation. Since E1A does not directly bind to and inhibit Bin1, the primary mechanism by which E1A counteracts Bin1 to liberate oncogenic c-Myc activity is poorly understood. Here we show that wild-type E1A, but not an Rb binding-defective E1A mutant, suppresses endogenous Bin1 expression in cultured rodent fibroblasts. Similarly, other anti-Rb agents, such as human papillomavirus E7, mitogenic stimuli, and small interfering RNA (siRNA) for Rb, consistently decrease Bin1 promoter activity. In contrast, serum starvation, which activates Rb, enhances endogenous Bin1 levels. These findings suggest that Bin1 may be a novel component of Rb-mediated G1 arrest. Consistent with this premise, chromatin immunoprecipitation assays demonstrate that Rb protein directly interacts with the Bin1 promoter only upon removal of serum. Furthermore, ectopically expressed E2F1, which is primarily inhibited by Rb under serum-starved condition, represses Bin1 promoter activity in a manner that is dependent on the DNA-binding and transactivation domains of E2F1. Lastly, depletion of endogenous Bin1 per se is biologically meaningful since antisense or siRNA of Bin1 transfection releases endogenous c-Myc transcriptional activity and, concomitantly, accelerates cell proliferation. Our results suggest that Bin1 gene suppression caused by oncogenic E1A via Rb inactivation is an essential step in cell cycle progression promoted by c-Myc, and subsequently, E1A transformation. We propose a novel G1 arrest signaling mechanism by which Rb indirectly curbs oncogenic c-Myc activity via sustaining Bin1 expression.
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Affiliation(s)
- Erica L Kinney
- Division of Cancer Biology, Department of Pathology, School of Medicine and Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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22
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Querin L, Sanvito R, Magni F, Busti S, Van Dorsselaer A, Alberghina L, Vanoni M. Proteomic analysis of a nutritional shift-up in Saccharomyces cerevisiae identifies Gvp36 as a BAR-containing protein involved in vesicular traffic and nutritional adaptation. J Biol Chem 2007; 283:4730-43. [PMID: 18156177 DOI: 10.1074/jbc.m707787200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Yeast cells undergoing a nutritional shift-up from a poor to a rich carbon source take several hours to adapt to the novel, richer carbon source. The budding index is a physiologically relevant "global" parameter that reflects the complex links between cell growth and division that are both coordinately and deeply affected by nutritional conditions. We used changes in budding index as a guide to choose appropriate, relevant time points during an ethanol to glucose nutritional shift-up for preparation of samples for the analysis of proteome by two-dimensional electrophoresis/mass spectrometry. About 600 spots were detected. 90 spots, mostly comprising proteins involved in intermediary metabolism, protein synthesis, and response to stress, showed differential expression after glucose addition. Among modulated proteins we identified a protein of previously unknown function, Gvp36, showing a transitory increase corresponding to the drop of the fraction of budded cells. A gvp36Delta strain shares several phenotypes (including general growth defects, heat shock, and high salt sensitivity, defects in polarization of the actin cytoskeleton, in endocytosis and in vacuolar biogenesis, defects in entering stationary phase upon nutrient starvation) with secretory pathway mutants and with mutants in genes encoding the two previously known yeast BAR proteins (RSV161 and RSV167). We thus propose that Gvp36 represents a novel yeast BAR protein involved in vesicular traffic and in nutritional adaptation.
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Affiliation(s)
- Lorenzo Querin
- Department of Biotechnology and Biosciences, University Milano-Bicocca, 20126 Milano, Italy
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23
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Chen RE, Thorner J. Function and regulation in MAPK signaling pathways: lessons learned from the yeast Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1773:1311-40. [PMID: 17604854 PMCID: PMC2031910 DOI: 10.1016/j.bbamcr.2007.05.003] [Citation(s) in RCA: 442] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 05/02/2007] [Accepted: 05/04/2007] [Indexed: 10/23/2022]
Abstract
Signaling pathways that activate different mitogen-activated protein kinases (MAPKs) elicit many of the responses that are evoked in cells by changes in certain environmental conditions and upon exposure to a variety of hormonal and other stimuli. These pathways were first elucidated in the unicellular eukaryote Saccharomyces cerevisiae (budding yeast). Studies of MAPK pathways in this organism continue to be especially informative in revealing the molecular mechanisms by which MAPK cascades operate, propagate signals, modulate cellular processes, and are controlled by regulatory factors both internal to and external to the pathways. Here we highlight recent advances and new insights about MAPK-based signaling that have been made through studies in yeast, which provide lessons directly applicable to, and that enhance our understanding of, MAPK-mediated signaling in mammalian cells.
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Affiliation(s)
- Raymond E Chen
- Division of Biochemistry and Molecular Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA
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24
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Krappmann AB, Taheri N, Heinrich M, Mösch HU. Distinct domains of yeast cortical tag proteins Bud8p and Bud9p confer polar localization and functionality. Mol Biol Cell 2007; 18:3323-39. [PMID: 17581861 PMCID: PMC1951750 DOI: 10.1091/mbc.e06-10-0899] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In Saccharomyces cerevisiae, diploid yeast cells follow a bipolar budding program, which depends on the two transmembrane glycoproteins Bud8p and Bud9p that potentially act as cortical tags to mark the cell poles. Here, we have performed systematic structure-function analyses of Bud8p and Bud9p to identify functional domains. We find that polar transport of Bud8p and Bud9p does not depend on N-terminal sequences but instead on sequences in the median part of the proteins and on the C-terminal parts that contain the transmembrane domains. We show that the guanosine diphosphate (GDP)/guanosine triphosphate (GTP) exchange factor Bud5p, which is essential for bud site selection and physically interacts with Bud8p, also interacts with Bud9p. Regions of Bud8p and Bud9p predicted to reside in the extracellular space are likely to confer interaction with the N-terminal region of Bud5p, implicating indirect interactions between the cortical tags and the GDP/GTP exchange factor. Finally, we have identified regions of Bud8p and Bud9p that are required for interaction with the cortical tag protein Rax1p. In summary, our study suggests that Bud8p and Bud9p carry distinct domains for delivery of the proteins to the cell poles, for interaction with the general budding machinery and for association with other cortical tag proteins.
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Affiliation(s)
| | - Naimeh Taheri
- Institute for Microbiology and Genetics, Georg-August University, D-37077 Göttingen, Germany
| | - Melanie Heinrich
- *Department of Genetics, Philipps-University, D-35032 Marburg, Germany; and
| | - Hans-Ulrich Mösch
- *Department of Genetics, Philipps-University, D-35032 Marburg, Germany; and
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25
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Abstract
Ubiquitylation of membrane proteins has gained considerable interest in recent years. It has been recognized as a signal that negatively regulates the cell surface expression of many plasma membrane proteins both in yeast and in mammalian cells. Moreover, it is also involved in endoplasmic reticulum-associated degradation of membrane proteins, and it acts as a sorting signal both in the secretory pathway and in endosomes, where it targets proteins into multivesicular bodies in the lumen of vacuoles/lysosomes. In this review we discuss the progress in understanding these processes, achieved during the past several years.
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Affiliation(s)
- Olivier Staub
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.
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26
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le Maire A, Weber T, Saunier S, Broutin I, Antignac C, Ducruix A, Dardel F. Solution NMR structure of the SH3 domain of human nephrocystin and analysis of a mutation-causing juvenile nephronophthisis. Proteins 2006; 59:347-55. [PMID: 15723349 DOI: 10.1002/prot.20344] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Human nephrocystin is a protein associated with juvenile NPH, an autosomal recessive, inherited kidney disease responsible for chronic renal failure in children. It contains an SH3 domain involved in signaling pathways controlling cell adhesion and cytoskeleton organization. The solution structure of this domain was solved by triple resonance NMR spectroscopy. Within the core, the structure is similar to those previously reported for other SH3 domains but exhibits a number of specific noncanonical features within the polyproline ligand binding site. Some of the key conserved residues are missing, and the N-Src loop exhibits an unusual twisted geometry, which results in a narrowing of the binding groove. This is induced by the replacement of a conserved Asp, Asn, or Glu residue by a Pro at one side of the N-Src loop. A systematic survey of other SH3 domains also containing a Pro at this position reveals that most of them belong to proteins involved in cell adhesion or motility. A variant of this domain, which carries a point mutation causing NPH, was also analyzed. This change, L180P, although it corresponds to a nonconserved and solvent-exposed position, causes a complete loss of the tertiary structure. Similar effects are also observed with the L180A variant. This could be a context-dependent effect resulting from an interaction between neighboring charged side-chains.
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Affiliation(s)
- Albane le Maire
- Laboratoire de Cristallographie et RMN Biologiques, UMR8015 CNRS, Faculté de Pharmacie, Université Paris 5, Paris, France
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27
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Friesen H, Humphries C, Ho Y, Schub O, Colwill K, Andrews B. Characterization of the yeast amphiphysins Rvs161p and Rvs167p reveals roles for the Rvs heterodimer in vivo. Mol Biol Cell 2006; 17:1306-21. [PMID: 16394103 PMCID: PMC1382319 DOI: 10.1091/mbc.e05-06-0476] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Revised: 12/13/2005] [Accepted: 12/27/2005] [Indexed: 11/11/2022] Open
Abstract
We have used comprehensive synthetic lethal screens and biochemical assays to examine the biological role of the yeast amphiphysin homologues Rvs161p and Rvs167p, two proteins that play a role in regulation of the actin cytoskeleton, endocytosis, and sporulation. We found that unlike some forms of amphiphysin, Rvs161p-Rvs167p acts as an obligate heterodimer during vegetative growth and neither Rvs161p nor Rvs167p forms a homodimer in vivo. RVS161 and RVS167 have an identical set of 49 synthetic lethal interactions, revealing functions for the Rvs proteins in cell polarity, cell wall synthesis, and vesicle trafficking as well as a shared role in mating. Consistent with these roles, we show that the Rvs167p-Rvs161p heterodimer, like its amphiphysin homologues, can bind to phospholipid membranes in vitro, suggesting a role in vesicle formation and/or fusion. Our genetic screens also reveal that the interaction between Abp1p and the Rvs167p Src homology 3 (SH3) domain may be important under certain conditions, providing the first genetic evidence for a role for the SH3 domain of Rvs167p. Our studies implicate heterodimerization of amphiphysin family proteins in various functions related to cell polarity, cell integrity, and vesicle trafficking during vegetative growth and the mating response.
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Affiliation(s)
- Helena Friesen
- Department of Medical Genetics and Microbiology, Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada M5S 1A8
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28
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Talarek N, Balguerie A, Aigle M, Durrens P. A novel link between a rab GTPase and Rvs proteins: the yeast amphiphysin homologues. Cell Biochem Funct 2005; 23:253-66. [PMID: 15473003 DOI: 10.1002/cbf.1146] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The BAR proteins are a well-conserved family of proteins including Rvsp in yeast, amphiphysins and Bin proteins in mammals. In yeast, as in mammals, BAR proteins are known to be implicated in vesicular traffic. The Gyp5p (Ypl249p) and Ymr192p proteins interact in two-hybrid tests with both Rvs161p and Rvs167p. Gyp5p is a Ypt/Rab-specific GAP and Ymr192p is highly similar to Gyp5p. To specify the interaction between Rvsp and Gyp5p, we used two-hybrid tests to determine the domains necessary for these interactions. The specific SH3 domain of Rvs167p interacted with the N-terminal domain of Gyp5p. Moreover, Gyp5p could form a homodimer. Fus2 protein is a specific partner of Rvs161p in two-hybrid tests. To characterize the functional relationships between these five proteins, we have studied cellular phenotypes in single, double and triple mutant strains for which rvs mutants present defects, such as polarity, cell fusion and meiosis. Phenotypic analysis showed that Gyp5p, Ymr192p and Fus2p were involved in bipolar budding pattern and in meiosis. Specific epistasis or suppressive phenomena were found between the five mutations. Finally, The Gyp5p-GFP fusion protein was localized at the bud tip during apical growth and at the mother-bud neck during cytokinesis. Moreover, Rvs167p and Rvs161p were shown to be essential for the correct localization of Gyp5p. Altogether, these data support the hypothesis that both Rvsp proteins act in vesicular traffic through physical and functional interactions with Ypt/Rab regulators.
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29
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Huang TY, Renaud-Young M, Young D. Nak1 interacts with Hob1 and Wsp1 to regulate cell growth and polarity in Schizosaccharomyces pombe. J Cell Sci 2005; 118:199-210. [PMID: 15615784 DOI: 10.1242/jcs.01608] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously reported that Nak1, a group-II germinal center (GC) kinase, is essential for polarized growth in Schizosaccharomyces pombe. Here, we provide evidence that Nak1 regulates cell growth and polarity, in part, through its interactions with Hob1 (an Rvs167/amphiphysin homolog) and Wsp1 (Wiskott-Aldrich-syndrome-protein homolog). We found that Nak1, Hob1 and Wsp1 interact physically, and that both Hob1/green-fluorescent-protein (Hob1-GFP) and Wsp1-GFP fusion proteins localized to F-actin patches at growing cell ends and medial division sites. Hob1-GFP was dissociated from patches in cells lacking Wsp1. Also, Hob1 overexpression dissociated Wsp1-GFP from foci, inhibited Wsp1-directed F-actin formation in vitro and partially restored polarity defects associated with Wsp1 overexpression or nak1 repression. Furthermore, loss of both Wsp1 and Hob1 resulted in rounded cells, slow growth and multiple septae. Together, these observations suggest that Hob1 and Wsp1 cooperate to mediate cell polarity, growth and division. Repression of nak1 resulted in a random redistribution of Hob1-GFP and Wsp1-GFP foci, and inhibition of Wsp1-directed F-actin formation in vitro. Furthermore, hob1delta and wsp1delta mutants exhibited synthetic growth defects in combination with nak1 repression, suggesting that Nak1 has redundant functions with Hob1 and Wsp1. Collectively, our results suggest that Nak1 both regulates and cooperates with Hob1 and Wsp1 to promote F-actin formation and polarized cell growth.
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Affiliation(s)
- Timothy Y Huang
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB T2N 4N1, Canada
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30
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Abstract
The budding yeast Saccharomyces cerevisiae responds to intracellular and extracellular cues to direct cell growth. Genetic analysis has revealed many components that participate in this process and has provided insight into the mechanisms by which these proteins function. Several of these components, such as the septins, pheromone receptors and GTPase proteins, have homologues in multicellular eukaryotes, suggesting that many aspects of polarized cell growth may be conserved throughout evolution. This review discusses our current understanding of the molecular mechanisms of growth-site selection during the different stages of the yeast life cycle.
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Affiliation(s)
- T Roemer
- Dept of Biology, Yale University, New Haven, CT 06520-8103, USA
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31
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Stamenova SD, Dunn R, Adler AS, Hicke L. The Rsp5 Ubiquitin Ligase Binds to and Ubiquitinates Members of the Yeast CIN85-Endophilin Complex, Sla1-Rvs167. J Biol Chem 2004; 279:16017-25. [PMID: 14761940 DOI: 10.1074/jbc.m313479200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sla1 and Rvs167 are yeast proteins required for receptor internalization and organization of the actin cytoskeleton. Here we provide evidence that Sla1 and Rvs167 are orthologues of the mammalian CIN85 and endophilin proteins, respectively, which are required for ligand-stimulated growth factor receptor internalization. Sla1 is similar in domain structure to CIN85 and binds directly to the endophilin-like Rvs167. Akin to CIN85, Sla1 interacts with synaptojanins and a ubiquitin ligase that regulates endocytosis. This ubiquitin ligase, Rsp5, binds directly to both Sla1 and Rvs167. The interaction between Rsp5 and Rvs167 is mediated through Rsp5 WW domains and PXY motifs in the central Gly-Pro-Ala-rich domain of Rvs167. Rvs167 PXY motifs are required for Rsp5-dependent monoubiquitination of Rvs167 on Lys481 in the Src homology 3 (SH3) domain. Mutation of Lys481 --> Arg causes cells to grow slowly on medium containing 1 M NaCl, although this phenotype is not due to the defect in ubiquitination caused by the K481R mutation. We propose that Rsp5 interaction with Sla1-Rvs167 promotes Rvs167 ubiquitination and regulates activity of this protein complex. Rvs167 ubiquitination is not required for general function of Rvs167, but may control specific Rvs167 SH3 domain-protein interactions or negatively regulate SH3 domain activity.
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Affiliation(s)
- Svetoslava D Stamenova
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500, USA
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Abstract
Internalization of receptors, lipids, pathogens, and other cargo at the plasma membrane involves several different pathways and requires coordinated interactions between a variety of protein and lipid molecules. The actin cytoskeleton is an integral part of the cell cortex, and there is growing evidence that F-actin plays a direct role in these endocytic events. Genetic studies in yeast have firmly established a functional connection between actin and endocytosis. Identification of several proteins that may function at the interface between actin and the endocytic machinery has provided further evidence for this association in both yeast and mammalian cells. Several of these proteins are directly involved in regulating actin assembly and could thus harness forces produced during actin polymerization to facilitate specific steps in the endocytic process. Recent microscopy studies in mammalian cells provide powerful evidence that localized recruitment and polymerization of actin occurs at endocytic sites. In this review, we focus on progress made in elucidating the functions of the actin cytoskeleton in endocytosis.
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Affiliation(s)
- Asa E Y Engqvist-Goldstein
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202, USA
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Sarret P, Esdaile MJ, McPherson PS, Schonbrunn A, Kreienkamp HJ, Beaudet A. Role of Amphiphysin II in Somatostatin Receptor Trafficking in Neuroendocrine Cells. J Biol Chem 2004; 279:8029-37. [PMID: 14660576 DOI: 10.1074/jbc.m310792200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Amphiphysins are SH3 domain-containing proteins thought to function in clathrin-mediated endocytosis. To investigate the potential role of amphiphysin II in cellular trafficking of G protein-coupled somatostatin (SRIF) receptors, we generated an AtT-20 cell line stably overexpressing amphiphysin IIb, a splice variant that does not bind clathrin. Endocytosis of (125)I-[d-Trp(8)]SRIF was not affected by amphiphysin IIb overexpression. However, the maximal binding capacity (B(max)) of the ligand on intact cells was significantly lower in amphiphysin IIb overexpressing than in non-transfected cells. This difference was no longer apparent when the experiments were performed on crude cell homogenates, suggesting that amphiphysin IIb overexpression interferes with SRIF receptor targeting to the cell surface and not with receptor synthesis. Accordingly, immunofluorescence experiments demonstrated that, in amphiphysin overexpressing cells, sst(2A) and sst(5) receptors were segregated in a juxtanuclear compartment identified as the trans-Golgi network. Amphiphysin IIb overexpression had no effect on corticotrophin-releasing factor 41-stimulated adrenocorticotropic hormone secretion, suggesting that it is not involved in the regulated secretory pathway. Taken together, these results suggest that amphiphysin II is not necessary for SRIF receptor endocytosis but is critical for its constitutive targeting to the plasma membrane. Therefore, amphiphysin IIb may be an important component of the constitutive secretory pathway.
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Affiliation(s)
- Philippe Sarret
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada
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Friesen H, Murphy K, Breitkreutz A, Tyers M, Andrews B. Regulation of the yeast amphiphysin homologue Rvs167p by phosphorylation. Mol Biol Cell 2003; 14:3027-40. [PMID: 12857883 PMCID: PMC165695 DOI: 10.1091/mbc.e02-09-0613] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The yeast amphiphysin homologue Rvs167p plays a role in regulation of the actin cytoskeleton, endocytosis, and sporulation. Rvs167p is a phosphoprotein in vegetatively growing cells and shows increased phosphorylation upon treatment with mating pheromone. Previous work has shown that Rvs167p can be phosphorylated in vitro by the cyclin-dependent kinase Pho85p complexed with its cyclin Pcl2p. Using chymotryptic phosphopeptide mapping, we have identified the sites on which Rvs167p is phosphorylated in vitro by Pcl2p-Pho85p. We have shown that these same sites are phosphorylated in vivo during vegetative growth and that phosphorylation at two of these sites is Pcl-Pho85p dependent. In cells treated with mating pheromone, the MAP kinase Fus3p is needed for full phosphorylation of Rvs167p. Functional genomics and genetics experiments revealed that mutation of other actin cytoskeleton genes compromises growth of a strain in which phosphorylation of Rvs167p is blocked by mutation. Phosphorylation of Rvs167p inhibits its interaction in vitro with Las17p, an activator of the Arp2/3 complex, as well as with a novel protein, Ymr192p. Our results suggest that phosphorylation of Rvs167p by a cyclin-dependent kinase and by a MAP kinase is an important mechanism for regulating protein complexes involved in actin cytoskeleton function.
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Affiliation(s)
- Helena Friesen
- Department of Molecular and Medical Genetics, University of Toronto, Toronto, Canada, M5S 1A8
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35
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DuHadaway JB, Du W, Donover S, Baker J, Liu AX, Sharp DM, Muller AJ, Prendergast GC. Transformation-selective apoptotic program triggered by farnesyltransferase inhibitors requires Bin1. Oncogene 2003; 22:3578-88. [PMID: 12789266 DOI: 10.1038/sj.onc.1206481] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Neoplastic transformation sensitizes many cells to apoptosis. This phenomenon may underlie the therapeutic benefit of many anticancer drugs, but its molecular basis is poorly understood. We have used a selective and potent farnesyltransferase inhibitor (FTI) to probe a mechanism of apoptosis that is peculiarly linked to neoplastic transformation. While nontoxic to untransformed mouse cells, FTI triggers a massive RhoB-dependent, p53-independent apoptosis in mouse cells that are neoplastically transformed. Here we offer evidence that the BAR adapter-encoding tumor suppressor gene Bin1 is required for this transformation-selective death program. Targeted deletion of Bin1 in primary mouse embyro fibroblasts (MEFs) transformed by E1A+Ras did not affect FTI-induced reversion, actin fiber formation, or growth inhibition, but it abolished FTI-induced apoptosis. The previously defined requirement for RhoB in these effects suggests that Bin1 adapter proteins act downstream or in parallel to RhoB in cell death signaling. The death defect in Bin1 null cells was significant insofar as it abolished FTI efficacy in tumor xenograft assays. p53 deletion did not phenocopy the effects of Bin1 deletion. However, MEFs transformed by SV40 large T antigen+Ras were also resistant to apoptosis by FTI, consistent with other evidence that large T inhibits Bin1-dependent cell death by a p53-independent mechanism. Taken together, the results define a function for Bin1 in apoptosis that is conditional on transformation stress. This study advances understanding of the functions of BAR adapter proteins, which are poorly understood, by revealing genetic interactions with an Rho small GTPase that functions in stress signaling. The frequent losses of Bin1 expression that occur in human breast and prostate cancers may promote tumor progression and limit susceptibility to FTI or other therapeutic agents that exploit the heightened sensitivity of neoplastic cells to apoptosis.
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Routhier EL, Donover PS, Prendergast GC. hob1+, the fission yeast homolog of Bin1, is dispensable for endocytosis or actin organization, but required for the response to starvation or genotoxic stress. Oncogene 2003; 22:637-48. [PMID: 12569356 DOI: 10.1038/sj.onc.1206162] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BAR (Bin/Amphiphysin/Rvs) adapter proteins have been suggested to regulate endocytosis, actin organization, apoptosis, and transcription, but their precise roles are obscure. There are at least five mammalian genes that encode BAR adapter proteins, including the evolutionarily conserved and ubiquitously expressed Bin1/Amphiphysin-II and Bin3 genes. Bin1 holds special interest as certain splice isoforms localize to the nucleus, interact with the c-Abl and c-Myc oncoproteins, and display tumor suppressor properties. To obtain functional insights, we embarked upon a genetic analysis of the two BAR adapter proteins expressed in the fission yeast Schizosaccharomyces pombe. In a previous work, a role in actin organization and cytokinesis was identified for the Bin3 homolog hob3+. In this study, a role in stress signaling was defined for the Bin1 homolog, hob1+. Notably, hob1+ was dispensable for endocytosis, actin organization, or osmotic sensitivity. Instead, mutation of hob1+ led to slight cell elongation and faulty cell cycle arrest upon nutrient starvation. These defects were complemented by Bin1, but not by Amphiphysin-I, arguing that these genes have distinct functions despite their structural similarity. hob1 delta mutant cells were also hypersensitive to genotoxic stress. This was not related to a faulty checkpoint response, but mutation in the checkpoint gene rad3(+) further exacerbated the sensitivity of hob1 delta mutant cells. Interestingly, mutation of the cell cycle regulator wee1+ partially relieved the sensitivity defect, suggesting that hob1+ may influence the efficiency of DNA repair or checkpoint release after DNA damage. Genetic and biochemical evidence indicated that hob3+ is epistatic to hob1+ in the response to genotoxic stress. Our findings indicate that the Bin1 homolog hob1+ participates in DNA damage signaling and they suggest a novel role for BAR adapter proteins in stress response processes.
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Affiliation(s)
- Eric L Routhier
- Cancer Research Group, The DuPont Pharmaceuticals Company, Glenolden, PA 19036, USA
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37
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Wang ZX, Kayingo G, Blomberg A, Prior BA. Cloning, sequencing and characterization of a gene encoding dihydroxyacetone kinase from Zygosaccharomyces rouxii NRRL2547. Yeast 2002; 19:1447-58. [PMID: 12478592 DOI: 10.1002/yea.928] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The dihydroxyacetone pathway, an alternative pathway for the dissimilation of glycerol via reduction by glycerol dehydrogenase and subsequent phosphorylation by dihydroxyacetone (DHA) kinase, is activated in the yeasts Saccharomyces cerevisiae and Zygosaccharomyces rouxii during osmotic stress. In experiments aimed at investigating the physiological function of the DHA pathway in Z. rouxii, a typical osmotolerant yeast, we cloned and characterized a DAK gene encoding dihydroxyacetone kinase from Z. rouxii NRRL 2547. Sequence analysis revealed a 1761 bp open reading frame, encoding a peptide composed of 587 deduced amino acids with the predicted molecular weight of 61 664 Da. As the amino acid sequence was most closely homologous (68% identity) to the S. cerevisiae Dak1p, we named the gene and protein ZrDAK1 and ZrDak1p, respectively. A putative ATP binding site was also found but no consensus element associated with osmoregulation was found in the upstream region of the ZrDAK1 gene. The ZrDAK1 gene complemented a S. cerevisiae W303-1A dak1delta dak2 delta strain by improving the growth of the mutant on 50 mmol/l dihydroxyacetone and by increasing the tolerance to dihydroxyacetone in a medium containing 5% sodium chloride, suggesting that it is a functional homologue of the S. cerevisiae DAK1. However, expression of the ZrDAK1 gene in the S. cerevisiae dak1delta dak2 delta strain had no significant effect on glycerol levels during osmotic stress. The ZrDAK1 sequence has been deposited in the public data bases under Accession No. AJ294719; regions upstream and downstream of ZrDAK1are deposited as Accession Nos AJ294739 and AJ294720, respectively.
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Affiliation(s)
- Zheng-Xiang Wang
- Department of Microbiology, University of Stellenbosch, Private Bag X1, 7602 Matieland, South Africa
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38
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Henry KR, D'Hondt K, Chang J, Newpher T, Huang K, Hudson RT, Riezman H, Lemmon SK. Scd5p and clathrin function are important for cortical actin organization, endocytosis, and localization of sla2p in yeast. Mol Biol Cell 2002; 13:2607-25. [PMID: 12181333 PMCID: PMC117929 DOI: 10.1091/mbc.e02-01-0012] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
SCD5 was identified as a multicopy suppressor of clathrin HC-deficient yeast. SCD5 is essential, but an scd5-Delta338 mutant, expressing Scd5p with a C-terminal truncation of 338 amino acids, is temperature sensitive for growth. Further studies here demonstrate that scd5-Delta338 affects receptor-mediated and fluid-phase endocytosis and normal actin organization. The scd5-Delta338 mutant contains larger and depolarized cortical actin patches and a prevalence of G-actin bars. scd5-Delta338 also displays synthetic negative genetic interactions with mutations in several other proteins important for cortical actin organization and endocytosis. Moreover, Scd5p colocalizes with cortical actin. Analysis has revealed that clathrin-deficient yeast also have a major defect in cortical actin organization and accumulate G-actin. Overexpression of SCD5 partially suppresses the actin defect of clathrin mutants, whereas combining scd5-Delta338 with a clathrin mutation exacerbates the actin and endocytic phenotypes. Both Scd5p and yeast clathrin physically associate with Sla2p, a homologue of the mammalian huntingtin interacting protein HIP1 and the related HIP1R. Furthermore, Sla2p localization at the cell cortex is dependent on Scd5p and clathrin function. Therefore, Scd5p and clathrin are important for actin organization and endocytosis, and Sla2p may provide a critical link between clathrin and the actin cytoskeleton in yeast, similar to HIP1(R) in animal cells.
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Affiliation(s)
- Kenneth R Henry
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland Ohio 44106, USA
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39
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Heese-Peck A, Pichler H, Zanolari B, Watanabe R, Daum G, Riezman H. Multiple functions of sterols in yeast endocytosis. Mol Biol Cell 2002; 13:2664-80. [PMID: 12181337 PMCID: PMC117933 DOI: 10.1091/mbc.e02-04-0186] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Sterols are essential factors for endocytosis in animals and yeast. To investigate the sterol structural requirements for yeast endocytosis, we created a variety of ergDelta mutants, each accumulating a distinct set of sterols different from ergosterol. Mutant erg2Deltaerg6Delta and erg3Deltaerg6Delta cells exhibit a strong internalization defect of the alpha-factor receptor (Ste2p). Specific sterol structures are necessary for pheromone-dependent receptor hyperphosphorylation, a prerequisite for internalization. The lack of phosphorylation is not due to a defect in Ste2p localization or in ligand-receptor interaction. Contrary to most known endocytic factors, sterols seem to function in internalization independently of actin. Furthermore, sterol structures are required at a postinternalization step of endocytosis. ergDelta cells were able to take up the membrane marker FM4-64, but exhibited defects in FM4-64 movement through endosomal compartments to the vacuole. Therefore, there are at least two roles for sterols in endocytosis. Based on sterol analysis, the sterol structural requirements for these two processes were different, suggesting that sterols may have distinct functions at different places in the endocytic pathway. Interestingly, sterol structures unable to support endocytosis allowed transport of the glycosylphosphatidylinositol-anchored protein Gas1p from the endoplasmic reticulum to Golgi compartment.
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40
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Zhang B, Zelhof AC. Amphiphysins: raising the BAR for synaptic vesicle recycling and membrane dynamics. Bin-Amphiphysin-Rvsp. Traffic 2002; 3:452-60. [PMID: 12047553 DOI: 10.1034/j.1600-0854.2002.30702.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Amphiphysins, members of the BAR (Bin-Amphiphysin-Rvsp) protein super family, have been postulated to play a key role in clathrin-mediated endocytosis of synaptic vesicles (SVs). This review focuses on recent genetic studies of the role of amphiphysins in SV recycling and membrane morphogenesis. In the mouse, brain-specific amphiphysin I and II regulate, but are not essential for, SV recycling. The role of this regulation appears important, as mice deficient in these proteins have seizures and are deficient in learning and memory. In the fruit fly Drosophila melanogaster, amphiphysin is found in muscles and is enriched at postsynaptic membranes of neuromuscular junctions (NMJs); however, it does not play a role in SV recycling. Rather, amphiphysin in fly muscles appears to regulate the organization and structure of the muscle T-tubule system and possibly the subsynaptic reticulum. Amphiphysin is also involved in membrane organization in both neurons and non-neuronal cells in Drosophila. These studies reveal pleiotropic functions for amphiphysins in clathrin-mediated endocytosis and the regulation of membrane dynamics, perhaps through the actin cytoskeleton.
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Affiliation(s)
- Bing Zhang
- Section of Neurobiology, University of Texas, Austin, TX 78712, USA.
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41
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Zelhof AC, Bao H, Hardy RW, Razzaq A, Zhang B, Doe CQ. DrosophilaAmphiphysin is implicated in protein localization and membrane morphogenesis but not in synaptic vesicle endocytosis. Development 2001; 128:5005-15. [PMID: 11748137 DOI: 10.1242/dev.128.24.5005] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Amphiphysin family members are implicated in synaptic vesicle endocytosis, actin localization and one isoform is an autoantigen in neurological autoimmune disorder; however, there has been no genetic analysis of Amphiphysin function in higher eukaryotes. We show that Drosophila Amphiphysin is localized to actin-rich membrane domains in many cell types, including apical epithelial membranes, the intricately folded apical rhabdomere membranes of photoreceptor neurons and the postsynaptic density of glutamatergic neuromuscular junctions. Flies that lack all Amphiphysin function are viable, lack any observable endocytic defects, but have abnormal localization of the postsynaptic proteins Discs large, Lethal giant larvae and Scribble, altered synaptic physiology, and behavioral defects. Misexpression of Amphiphysin outside its normal membrane domain in photoreceptor neurons results in striking morphological defects. The strong misexpression phenotype coupled with the mild mutant and lack of phenotypes suggests that Amphiphysin acts redundantly with other proteins to organize specialized membrane domains within a diverse array of cell types.
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Affiliation(s)
- A C Zelhof
- Institute of Neuroscience, HHMI, University of Oregon 1254, Eugene, OR 97403, USA
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42
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Leventis PA, Chow BM, Stewart BA, Iyengar B, Campos AR, Boulianne GL. Drosophila Amphiphysin is a post-synaptic protein required for normal locomotion but not endocytosis. Traffic 2001; 2:839-50. [PMID: 11733051 DOI: 10.1034/j.1600-0854.2001.21113.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Clathrin-mediated endocytosis is required to recycle synaptic vesicles for fast and efficient neurotransmission. Amphiphysins are thought to be multiprotein adaptors that may contribute to this process by bringing together many of the proteins required for endocytosis. Their in vivo function, however, has yet to be determined. Here, we show that the Drosophila genome encodes a single amphiphysin gene that is broadly expressed during development. We also show that, unlike its vertebrate counterparts, Drosophila Amphiphysin is enriched postsynaptically at the larval neuromuscular junction. To determine the role of Drosophila Amphiphysin, we also generated null mutants which are viable but give rise to larvae and adults with pronounced locomotory defects. Surprisingly, the locomotory defects cannot be accounted for by alterations in the morphology or physiology of the neuromuscular junction. Moreover, using stimulus protocols designed to test endocytosis under moderate and extreme vesicle cycling, we could not detect any defect in the neuromuscular junction of the amphiphysin mutant. Taken together, our findings suggest that Amphiphysin is not required for viability, nor is it absolutely required for clathrin-mediated endocytosis. However, Drosophila Amphiphysin function is required in both larvae and adults for normal locomotion.
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Affiliation(s)
- P A Leventis
- Department of Zoology, University of Toronto, Toronto, Canada
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43
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Kim KC, Kim TS, Kang KH, Choi KH. Amphiphysin IIb-1, a novel splicing variant of amphiphysin II, regulates p73beta function through protein-protein interactions. Oncogene 2001; 20:6689-99. [PMID: 11709703 DOI: 10.1038/sj.onc.1204839] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2001] [Revised: 04/02/2001] [Accepted: 07/16/2001] [Indexed: 11/09/2022]
Abstract
p73 is a nuclear protein that is similar in structure and function to p53. Notably, the C-terminal region of p73 has a regulatory function, through interactions with a positive or negative regulator. In this study, we use the yeast two-hybrid technique to identify a novel p73beta binding protein, designated amphiphysin IIb-1. Amphiphysin IIb-1 is one of the splicing variants of amphiphysin II, and has a shorter protein product than amphiphysin IIb, which has been previously reported. We confirmed that amphiphysin IIb-1 binds full-length p73beta, both in vitro and in vivo. This association is mediated via the SH3 domain of amphiphysin IIb-1 and C-terminal amino acids 321-376 of p73beta. Double immunofluorescence patterns revealed that p73beta is relocalized to the cytoplasm in the presence of amphiphysin IIb-1. Overexpression of amphiphysin IIb-1 was found to significantly inhibit the transcriptional activity of p73beta in a dose-dependent manner. In addition, the cell death function of p73beta was inhibited by amphiphysin IIb-1. These findings offer a new insight into the regulation mechanism of p73beta, and suggest that amphiphysin IIb-1 modulates p73beta function by direct binding.
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Affiliation(s)
- K C Kim
- Laboratory of Molecular Biology, Department of Biology, College of Natural Sciences, Chung-Ang University, Heuksuk Dong, Dongjak Ku, Seoul 156-756, Korea
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44
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Breton AM, Schaeffer J, Aigle M. The yeast Rvs161 and Rvs167 proteins are involved in secretory vesicles targeting the plasma membrane and in cell integrity. Yeast 2001; 18:1053-68. [PMID: 11481676 DOI: 10.1002/yea.755] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The Rvs161 and Rvs167 proteins are known to play a role in actin cytokeleton organization and endocytosis. Moreover, Rvs167p functionally interacts with the myosin Myo2p. Therefore, we explored the involvement of the Rvs proteins in vesicle traffic and in cell integrity. The rvs mutants accumulate late secretory vesicles at sites of membrane and cell wall construction. They are synthetic-lethal with the slt2/mpk1 mutation, which affects the MAP kinase cascade controlled by Pkc1p and is required for cell integrity. The phenotype of the double mutants is close to that described for the pkc1 mutant. Synthetic defects for growth are also observed with mutation in KRE6, a gene coding for a glucan synthase, required for cell wall construction. These data support the idea that the Rvs proteins are involved in the late targeting of vesicles whose cargoes are required for cell wall construction.
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Affiliation(s)
- A M Breton
- Laboratoire de Biologie Cellulaire de la Levure, LBCL/IBGC/CNRS UMR 5095, 1 Rue Camille Saint-Saëns, F-33077 Bordeaux Cedex, France.
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45
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Ni L, Snyder M. A genomic study of the bipolar bud site selection pattern in Saccharomyces cerevisiae. Mol Biol Cell 2001; 12:2147-70. [PMID: 11452010 PMCID: PMC55669 DOI: 10.1091/mbc.12.7.2147] [Citation(s) in RCA: 236] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2001] [Revised: 04/17/2001] [Accepted: 04/26/2001] [Indexed: 11/11/2022] Open
Abstract
A genome-wide screen of 4168 homozygous diploid yeast deletion strains has been performed to identify nonessential genes that participate in the bipolar budding pattern. By examining bud scar patterns representing the sites of previous cell divisions, 127 mutants representing three different phenotypes were found: unipolar, axial-like, and random. From this screen, 11 functional classes of known genes were identified, including those involved in actin-cytoskeleton organization, general bud site selection, cell polarity, vesicular transport, cell wall synthesis, protein modification, transcription, nuclear function, translation, and other functions. Four characterized genes that were not known previously to participate in bud site selection were also found to be important for the haploid axial budding pattern. In addition to known genes, we found 22 novel genes (20 are designated BUD13-BUD32) important for bud site selection. Deletion of one resulted in unipolar budding exclusively from the proximal pole, suggesting that this gene plays an important role in diploid distal budding. Mutations in 20 other novel BUD genes produced a random budding phenotype and one produced an axial-like budding defect. Several of the novel Bud proteins were fused to green fluorescence protein; two proteins were found to localize to sites of polarized cell growth (i.e., the bud tip in small budded cells and the neck in cells undergoing cytokinesis), similar to that postulated for the bipolar signals and proteins that target cell division site tags to their proper location in the cell. Four others localized to the nucleus, suggesting that they play a role in gene expression. The bipolar distal marker Bud8 was localized in a number of mutants; many showed an altered Bud8-green fluorescence protein localization pattern. Through the genome-wide identification and analysis of different mutants involved in bipolar bud site selection, an integrated pathway for this process is presented in which proximal and distal bud site selection tags are synthesized and localized at their appropriate poles, thereby directing growth at those sites. Genome-wide screens of defined collections of mutants hold significant promise for dissecting many biological processes in yeast.
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Affiliation(s)
- L Ni
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
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46
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Routhier EL, Burn TC, Abbaszade I, Summers M, Albright CF, Prendergast GC. Human BIN3 complements the F-actin localization defects caused by loss of Hob3p, the fission yeast homolog of Rvs161p. J Biol Chem 2001; 276:21670-7. [PMID: 11274158 DOI: 10.1074/jbc.m101096200] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The BAR adaptor proteins encoded by the RVS167 and RVS161 genes from Saccharomyces cerevisiae form a complex that regulates actin, endocytosis, and viability following starvation or osmotic stress. In this study, we identified a human homolog of RVS161, termed BIN3 (bridging integrator-3), and a Schizosaccharomyces pombe homolog of RVS161, termed hob3+ (homolog of Bin3). In human tissues, the BIN3 gene was expressed ubiquitously except for brain. S. pombe cells lacking Hob3p were often multinucleate and characterized by increased amounts of calcofluor-stained material and mislocalized F-actin. For example, while wild-type cells localized F-actin to cell ends during interphase, hob3Delta mutants had F-actin patches distributed randomly around the cell. In addition, medial F-actin rings were rarely found in hob3Delta mutants. Notably, in contrast to S. cerevisiae rvs161Delta mutants, hob3Delta mutants showed no measurable defects in endocytosis or response to osmotic stress, yet hob3+ complemented the osmosensitivity of a rvs161Delta mutant. BIN3 failed to rescue the osmosensitivity of rvs161Delta, but the actin localization defects of hob3Delta mutants were completely rescued by BIN3 and partially rescued by RVS161. These findings suggest that hob3+ and BIN3 regulate F-actin localization, like RVS161, but that other roles for this gene have diverged somewhat during evolution.
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Affiliation(s)
- E L Routhier
- Cancer Research Group, DuPont Pharmaceuticals Company, Glenolden Laboratory, Glenolden, Pennsylvania 19036, USA
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47
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Munn AL. Molecular requirements for the internalisation step of endocytosis: insights from yeast. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1535:236-57. [PMID: 11278164 DOI: 10.1016/s0925-4439(01)00028-x] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Molecular genetic studies of endocytosis using the unicellular eukaryote Saccharomyces cerevisiae (budding yeast) have led to the identification of many cellular components, both proteins and lipids, required for this process. While initially, many of these requirements (e.g. for actin, various actin-associated proteins, the ubiquitin conjugation system, and for ergosterol and sphingolipids) appeared to differ from known requirements for endocytosis in higher eukaryotes (e.g. clathrin, AP-2, dynamin), it now seems that endocytosis in higher and lower eukaryotes share many requirements. Often, what were initially identified as actin cytoskeleton-associated proteins in S. cerevisiae, are now revealing themselves as clathrin-coated pit- and vesicle-associated proteins in higher eukaryotes. So rather than delineating two endocytic pathways, one actin-based and one clathrin-based, the combined studies on higher and lower eukaryotes are revealing interesting interplay in both systems between the actin cytoskeleton, clathrin coats, and lipids in the formation of endocytic vesicles at the plasma membrane. Recent results from the yeast system show that the Arp2/3p complex, Wiskott-Aldrich syndrome protein (WASP), and WASP-interacting protein (WIP), proteins involved in the nucleation step of actin filament assembly, play a major role in the formation of endocytic vesicles. This discovery suggests models whereby endocytic vesicles may be actively pushed from the plasma membrane and into the cell by newly forming and rapidly extending actin filaments.
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Affiliation(s)
- A L Munn
- Laboratory of Yeast Cell Biology, Institute of Molecular Agrobiology, 1 Research Link, National University of Singapore, 117604, Singapore.
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48
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Floyd SR, Porro EB, Slepnev VI, Ochoa GC, Tsai LH, De Camilli P. Amphiphysin 1 binds the cyclin-dependent kinase (cdk) 5 regulatory subunit p35 and is phosphorylated by cdk5 and cdc2. J Biol Chem 2001; 276:8104-10. [PMID: 11113134 DOI: 10.1074/jbc.m008932200] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Amphiphysin 1 is a phosphoprotein expressed at high levels in neurons, where it participates in synaptic vesicle endocytosis and neurite outgrowth. It is a substrate for cyclin-dependent kinase (cdk) 5, a member of the cyclin-dependent protein kinase family, which has been functionally linked to neuronal migration and neurite outgrowth via its action on the actin cytoskeleton. The yeast homologue of amphiphysin, Rvs167, functions in endocytosis and actin dynamics, is phosphorylated by the cdk5 homologue Pho85, and binds the Pho85 regulatory subunit Pcl2. We show here that amphiphysin 1 interacts with the cdk5-activating subunit p35 and that this interaction is mediated by the conserved NH2-terminal region of amphiphysin. Amphiphysin 1 colocalizes with p35 in the growth cones of neurons and at actin-rich peripheral lamellipodia in transfected fibroblasts. Amphiphysin is phosphorylated by cdk5 in a region including serines 272, 276, and 285. Amphiphysin 1 is also phosphorylated by the cdc2/cyclin B kinase complex in the same region and undergoes mitotic phosphorylation in dividing cells. These data indicate that phosphorylation by members of the cyclin-dependent kinase family is a conserved property of amphiphysin and suggest that this phosphorylation may play an important physiological role both in mitosis and in differentiated cells.
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Affiliation(s)
- S R Floyd
- Howard Hughes Medical Institute and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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49
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Lombardi R, Riezman H. Rvs161p and Rvs167p, the two yeast amphiphysin homologs, function together in vivo. J Biol Chem 2001; 276:6016-22. [PMID: 11096097 DOI: 10.1074/jbc.m008735200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in RVS161 and RVS167, the two yeast amphiphysin homologs, cause very similar growth phenotypes, a depolarized actin cytoskeleton, and a defect in the internalization step of endocytosis. Rvs161p and Rvs167p have been shown to interact in the two-hybrid system, but their localization in the cell may be different thus raising the question whether the interaction is physiologically relevant. Here we demonstrate that the two proteins function together in vivo. We find that the steady state level of Rvs167p is strongly reduced in an rvs161Delta strain. Similarly, the level of Rvs161p is strongly reduced in an rvs167Delta strain. We demonstrate that these reduced protein levels at steady state are due to a decreased stability of either Rvs protein in the absence of the other protein. Furthermore, we find that the amount and ratio of Rvs161p and Rvs167p are critical parameters for receptor-mediated endocytosis. In addition, by using the two-hybrid system we show that the interaction of Rvs167p with actin is not abolished in an abp1Delta strain suggesting that Abp1p is not essential for this interaction.
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Affiliation(s)
- R Lombardi
- Biozentrum of the University of Basel, CH-4056 Basel, Switzerland
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50
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Whitacre J, Davis D, Toenjes K, Brower S, Adams A. Generation of an isogenic collection of yeast actin mutants and identification of three interrelated phenotypes. Genetics 2001; 157:533-43. [PMID: 11156976 PMCID: PMC1461522 DOI: 10.1093/genetics/157.2.533] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A large collection of yeast actin mutations has been previously isolated and used in numerous studies of actin cytoskeletal function. However, the various mutations have been in congenic, rather than isogenic, backgrounds, making it difficult to compare the subtle phenotypes that are characteristic of these mutants. We have therefore placed 27 mutations in an isogenic background. We used a subset of these mutants to compare the degree to which different actin alleles are defective in sporulation, endocytosis, and growth on NaCl-containing media. We found that the three phenotypes are highly correlated. The correlations are specific and not merely a reflection of general growth defects, because the phenotypes are not correlated with growth rates under normal conditions. Significantly, those actin mutants exhibiting the most severe phenotypes in all three processes have altered residues that cluster to a small region of the actin crystal structure previously defined as the fimbrin (Sac6p)-binding site. We examined the relationship between endocytosis and growth on salt and found that shifting wild-type or actin mutant cells to high salt reduces the rate of alpha-factor internalization. These results suggest that actin mutants may be unable to grow on salt because of additive endocytic defects (due to mutation and salt).
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Affiliation(s)
- J Whitacre
- Department of Molecular & Cellular Biology, University of Arizona, Tucson, AZ 85721, USA.
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