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Insertional mutagenesis in Chlamydomonas reinhardtii: An effective strategy for the identification of new genes involved in the DNA damage response. Eur J Protistol 2021; 82:125855. [PMID: 34954500 DOI: 10.1016/j.ejop.2021.125855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 11/26/2021] [Accepted: 12/02/2021] [Indexed: 11/23/2022]
Abstract
The formation of double-strand breaks in DNA represents a serious stress for all types of organisms and requires a precisely regulated and organized DNA damage response (DDR) to maintain genetic information and genome integrity. Chlamydomonas reinhardtii possesses the characteristics of both plants and animals and is therefore suitable for the identification of novel genes connected to a wide spectrum of metabolic pathways, including DDR. One very effective tool for the detection and subsequent characterization of new mutants in C. reinhardtii is insertional mutagenesis. We isolated several insertion mutants sensitive to DNA-damaging agents that had disrupted or completely deleted genes with putative functions in the DDR. In most of the analysed mutants, we identified various changes at both ends and even inside the inserted cassette. Using recent information from databases, we were also able to supplement the characteristics of the previously described mutant with a pleiotropic phenotype. In addition, we confirmed the effectiveness of hairpin-PCR as a strategy for the identification of insertion flanking sites and as a tool for the detection of changes at the site of insertion, thus enabling a better understanding of insertion events.
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Weber M, Basu S, González B, Greslehner GP, Singer S, Haskova D, Hasek J, Breitenbach M, W.Gourlay C, Cullen PJ, Rinnerthaler M. Actin Cytoskeleton Regulation by the Yeast NADPH Oxidase Yno1p Impacts Processes Controlled by MAPK Pathways. Antioxidants (Basel) 2021; 10:antiox10020322. [PMID: 33671669 PMCID: PMC7926930 DOI: 10.3390/antiox10020322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 01/21/2023] Open
Abstract
Reactive oxygen species (ROS) that exceed the antioxidative capacity of the cell can be harmful and are termed oxidative stress. Increasing evidence suggests that ROS are not exclusively detrimental, but can fulfill important signaling functions. Recently, we have been able to demonstrate that a NADPH oxidase-like enzyme (termed Yno1p) exists in the single-celled organism Saccharomyces cerevisiae. This enzyme resides in the peripheral and perinuclear endoplasmic reticulum and functions in close proximity to the plasma membrane. Its product, hydrogen peroxide, which is also produced by the action of the superoxide dismutase, Sod1p, influences signaling of key regulatory proteins Ras2p and Yck1p/2p. In the present work, we demonstrate that Yno1p-derived H2O2 regulates outputs controlled by three MAP kinase pathways that can share components: the filamentous growth (filamentous growth MAPK (fMAPK)), pheromone response, and osmotic stress response (hyperosmolarity glycerol response, HOG) pathways. A key structural component and regulator in this process is the actin cytoskeleton. The nucleation and stabilization of actin are regulated by Yno1p. Cells lacking YNO1 showed reduced invasive growth, which could be reversed by stimulation of actin nucleation. Additionally, under osmotic stress, the vacuoles of a ∆yno1 strain show an enhanced fragmentation. During pheromone response induced by the addition of alpha-factor, Yno1p is responsible for a burst of ROS. Collectively, these results broaden the roles of ROS to encompass microbial differentiation responses and stress responses controlled by MAPK pathways.
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Affiliation(s)
- Manuela Weber
- Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria; (M.W.); (G.P.G.); (S.S.); (M.B.)
| | - Sukanya Basu
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260-1300, USA; (S.B.); (B.G.)
| | - Beatriz González
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260-1300, USA; (S.B.); (B.G.)
| | - Gregor P. Greslehner
- Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria; (M.W.); (G.P.G.); (S.S.); (M.B.)
| | - Stefanie Singer
- Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria; (M.W.); (G.P.G.); (S.S.); (M.B.)
| | - Danusa Haskova
- Laboratory of Cell Reproduction, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 20 Prague 4, Czech Republic; (D.H.); (J.H.)
| | - Jiri Hasek
- Laboratory of Cell Reproduction, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 20 Prague 4, Czech Republic; (D.H.); (J.H.)
| | - Michael Breitenbach
- Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria; (M.W.); (G.P.G.); (S.S.); (M.B.)
| | - Campbell W.Gourlay
- Kent Fungal Group, School of Biosciences, University of Kent, Kent CT2 9HY, UK;
| | - Paul J. Cullen
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260-1300, USA; (S.B.); (B.G.)
- Correspondence: (P.J.C.); (M.R.)
| | - Mark Rinnerthaler
- Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria; (M.W.); (G.P.G.); (S.S.); (M.B.)
- Correspondence: (P.J.C.); (M.R.)
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3
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Sokolik CG, Qassem N, Chill JH. The Disordered Cellular Multi-Tasker WIP and Its Protein-Protein Interactions: A Structural View. Biomolecules 2020; 10:biom10071084. [PMID: 32708183 PMCID: PMC7407642 DOI: 10.3390/biom10071084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/16/2020] [Accepted: 07/18/2020] [Indexed: 01/21/2023] Open
Abstract
WASp-interacting protein (WIP), a regulator of actin cytoskeleton assembly and remodeling, is a cellular multi-tasker and a key member of a network of protein-protein interactions, with significant impact on health and disease. Here, we attempt to complement the well-established understanding of WIP function from cell biology studies, summarized in several reviews, with a structural description of WIP interactions, highlighting works that present a molecular view of WIP's protein-protein interactions. This provides a deeper understanding of the mechanisms by which WIP mediates its biological functions. The fully disordered WIP also serves as an intriguing example of how intrinsically disordered proteins (IDPs) exert their function. WIP consists of consecutive small functional domains and motifs that interact with a host of cellular partners, with a striking preponderance of proline-rich motif capable of interactions with several well-recognized binding partners; indeed, over 30% of the WIP primary structure are proline residues. We focus on the binding motifs and binding interfaces of three important WIP segments, the actin-binding N-terminal domain, the central domain that binds SH3 domains of various interaction partners, and the WASp-binding C-terminal domain. Beyond the obvious importance of a more fundamental understanding of the biology of this central cellular player, this approach carries an immediate and highly beneficial effect on drug-design efforts targeting WIP and its binding partners. These factors make the value of such structural studies, challenging as they are, readily apparent.
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Michard C, Yum LK, Agaisse H. WIPF2 promotesShigella flexneriactin‐based motility and cell‐to‐cell spread. Cell Microbiol 2019; 21:e13098. [DOI: 10.1111/cmi.13098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 08/08/2019] [Accepted: 08/10/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Céline Michard
- Department of Microbiology, Immunology, and Cancer BiologyUniversity of Virginia Charlottesville Virginia
| | - Lauren K. Yum
- Department of Microbiology, Immunology, and Cancer BiologyUniversity of Virginia Charlottesville Virginia
| | - Hervé Agaisse
- Department of Microbiology, Immunology, and Cancer BiologyUniversity of Virginia Charlottesville Virginia
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5
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The regulation of junctional actin dynamics by cell adhesion receptors. Histochem Cell Biol 2018; 150:341-350. [DOI: 10.1007/s00418-018-1691-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2018] [Indexed: 11/26/2022]
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WIP-YAP/TAZ as A New Pro-Oncogenic Pathway in Glioma. Cancers (Basel) 2018; 10:cancers10060191. [PMID: 29890731 PMCID: PMC6024887 DOI: 10.3390/cancers10060191] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/06/2018] [Accepted: 06/07/2018] [Indexed: 12/18/2022] Open
Abstract
Wild-type p53 (wtp53) is described as a tumour suppressor gene, and mutations in p53 occur in many human cancers. Indeed, in high-grade malignant glioma, numerous molecular genetics studies have established central roles of RTK-PI3K-PTEN and ARF-MDM2-p53 INK4a-RB pathways in promoting oncogenic capacity. Deregulation of these signalling pathways, among others, drives changes in the glial/stem cell state and environment that permit autonomous growth. The initially transformed cell may undergo subsequent modifications, acquiring a more complete tumour-initiating phenotype responsible for disease advancement to stages that are more aggressive. We recently established that the oncogenic activity of mutant p53 (mtp53) is driven by the actin cytoskeleton-associated protein WIP (WASP-interacting protein), correlated with tumour growth, and more importantly that both proteins are responsible for the tumour-initiating cell phenotype. We reported that WIP knockdown in mtp53-expressing glioblastoma greatly reduced proliferation and growth capacity of cancer stem cell (CSC)-like cells and decreased CSC-like markers, such as hyaluronic acid receptor (CD44), prominin-1 (CD133), yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ). We thus propose a new CSC signalling pathway downstream of mtp53 in which Akt regulates WIP and controls YAP/TAZ stability. WIP drives a mechanism that stimulates growth signals, promoting YAP/TAZ and β-catenin stability in a Hippo-independent fashion, which allows cells to coordinate processes such as proliferation, stemness and invasiveness, which are key factors in cancer progression. Based on this multistep tumourigenic model, it is tantalizing to propose that WIP inhibitors may be applied as an effective anti-cancer therapy.
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Chen CC, Chiou SH, Yang CL, Chow KC, Lin TY, Chang HW, You WC, Huang HW, Chen CM, Chen NC, Chou FP, Chou MC. Secreted gelsolin desensitizes and induces apoptosis of infiltrated lymphocytes in prostate cancer. Oncotarget 2017; 8:77152-77167. [PMID: 29100377 PMCID: PMC5652770 DOI: 10.18632/oncotarget.20414] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 06/12/2017] [Indexed: 12/16/2022] Open
Abstract
Loss of immunosurveillance is a major cause of cancer progression. Here, we demonstrate that gelsolin, a constituent of ejaculate, induces apoptosis of activated lymphocytes in prostate cancer. Gelsolin was highly expressed in prostate cancer cells, and was associated with tumor progression, recurrence, metastasis, and poor prognosis. In vitro, secreted gelsolin inactivated CD4+ T cells by binding to CD37, and induced apoptosis of activated CD8+ T lymphocytes by binding to Fas ligand during cell contact dependent on major histocompatibility complex I. Moreover, secreted gelsolin bound to sortilin, which in turn bound to Wiskott-Aldrich syndrome protein family member 3, thereby enhancing the endocytosis and intracellular transport of essential lipids needed to facilitate tumor growth and expansion. Under normal conditions, gelsolin is a seemingly harmless protein that prevents immune responses in female recipients. In disease states, however, this protein can inhibit immunosurveillance and promote cancer progression.
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Affiliation(s)
- Chun-Chi Chen
- Institute of Medicine, Chung-Shan Medical University, Taichung, Taiwan.,Section of Urology, Departments of Surgery, Changhua Christian Hospital, Chang-Hua, Taiwan
| | - Shiow-Her Chiou
- Graduate Institute of Microbiology and Public Health, National Chung Hsing University, Taichung, Taiwan
| | - Cheng-Lin Yang
- Graduate Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Kuan-Chih Chow
- Graduate Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Tze-Yi Lin
- Department of Pathology, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - Hui-Wen Chang
- Department of Pathology, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - Weir-Chiang You
- Department of Radiation Oncology, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Hisu-Wen Huang
- Endemic Species Research Institute, Council of Agriculture, Executive Yuan, Chi-Chi, Taiwan
| | - Chien-Min Chen
- Endemic Species Research Institute, Council of Agriculture, Executive Yuan, Chi-Chi, Taiwan
| | - Nien-Cheng Chen
- Institute of Biochemistry, Microbiology and Immunology, Chung-Shan Medical University, Taichung, Taiwan
| | - Fen-Pi Chou
- Institute of Biochemistry, Microbiology and Immunology, Chung-Shan Medical University, Taichung, Taiwan
| | - Ming-Chih Chou
- Institute of Medicine, Chung-Shan Medical University, Taichung, Taiwan.,Department of Family and Community Medicine, Chung-Shan Medical University Hospital, Chung-Shan Medical University, Taichung, Taiwan
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8
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Escoll M, Gargini R, Cuadrado A, Anton IM, Wandosell F. Mutant p53 oncogenic functions in cancer stem cells are regulated by WIP through YAP/TAZ. Oncogene 2017; 36:3515-3527. [DOI: 10.1038/onc.2016.518] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 12/13/2016] [Accepted: 12/22/2016] [Indexed: 02/07/2023]
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9
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Kropyvko S, Gryaznova T, Morderer D, Rynditch A. Mammalian verprolin CR16 acts as a modulator of ITSN scaffold proteins association with actin. Biochem Biophys Res Commun 2017; 484:813-819. [PMID: 28161632 DOI: 10.1016/j.bbrc.2017.01.177] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 01/31/2017] [Indexed: 02/03/2023]
Abstract
Actin cytoskeleton rearrangements are required for normal cell functioning, and their deregulation leads to various pathologies. Members of two mammalian protein families - ITSNs (ITSN1 and ITSN2) and verprolins (WIP, CR16 and WIRE) are involved in Cdc42/N-WASP/Arp2/3 signaling pathway-mediated remodeling of the actin cytoskeleton. Recently we demonstrated that ITSNs interact with the actin-regulating protein WIP. Here, we show that other member of verprolin family, CR16, also forms complexes with ITSN1 and ITSN2 in human cell lines. The actin-binding protein CR16 modulates ITSN/β-actin association. Moreover, overexpressed CR16 promoted co-localization of ITSN1 with F-actin in MCF-7 breast cancer cells. Our data demonstrated that CR16 mRNA is expressed in glioblastoma and breast tumors. These findings provide the basis for further functional investigations of the ITSN/CR16 complex that may play an important role in actin remodeling and cellular invasion.
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Affiliation(s)
- Sergii Kropyvko
- Institute of Molecular Biology and Genetics, 150 Zabolotnogo Street, Kyiv 03143, Ukraine.
| | - Tetyana Gryaznova
- Institute of Molecular Biology and Genetics, 150 Zabolotnogo Street, Kyiv 03143, Ukraine
| | - Dmytro Morderer
- Institute of Molecular Biology and Genetics, 150 Zabolotnogo Street, Kyiv 03143, Ukraine
| | - Alla Rynditch
- Institute of Molecular Biology and Genetics, 150 Zabolotnogo Street, Kyiv 03143, Ukraine
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10
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Huang L, Zhang S, Yin Z, Liu M, Li B, Zhang H, Zheng X, Wang P, Zhang Z. MoVrp1, a putative verprolin protein, is required for asexual development and infection in the rice blast fungus Magnaporthe oryzae. Sci Rep 2017; 7:41148. [PMID: 28117435 PMCID: PMC5259722 DOI: 10.1038/srep41148] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 12/15/2016] [Indexed: 01/04/2023] Open
Abstract
Endocytosis is a crucial cellular process in eukaryotic cells which involves clathrin and/or adaptor proteins, lipid kinases, phosphatases and the actin cytoskeleton. Verprolin proteins, such as Vrp1 in Saccharomyces cerevisiae, are conserved family proteins that regulate actin binding and endocytosis. Here, we identified and characterized MoVrp1 as the yeast Vrp1 homolog in Magnaporthe oryzae. Deletion of the MoVRP1 gene resulted in defects in vegetative growth, asexual development, and infection of the host plant. The ∆Movrp1 mutants also exhibited decreased extracellular peroxidase and laccase activities and showed defects in colony pigmentation, hyphal surface hydrophobicity, cell wall integrity, autophagy, endocytosis, and secretion of avirulent effector. Our studies provided new evidences that MoVrp1 involved in actin cytoskeleton is important for growth, morphogenesis, cellular trafficking, and fungal pathogenesis.
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Affiliation(s)
- Lin Huang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China.,College of Forestry and Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Shengpei Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Ziyi Yin
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Muxing Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Bing Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
| | - Ping Wang
- Department of Pediatrics, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70118, USA
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, China
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11
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Elazari-Shalom H, Shaked H, Esteban-Martin S, Salvatella X, Barda-Saad M, Chill JH. New insights into the role of the disordered WIP N-terminal domain revealed by NMR structural characterization. FEBS J 2015; 282:700-14. [DOI: 10.1111/febs.13174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 12/04/2014] [Accepted: 12/09/2014] [Indexed: 02/06/2023]
Affiliation(s)
| | - Hadassa Shaked
- Department of Chemistry; Bar Ilan University; Ramat Gan Israel
| | - Santiago Esteban-Martin
- Joint BSC-CRG-IRB Research Programme in Computational Biology; Barcelona Supercomputing Center; Spain
| | - Xavier Salvatella
- Joint BSC-CRG-IRB Research Programme in Computational Biology; Institute for Research in Biomedicine IRB Barcelona; Spain
- ICREA; Barcelona Spain
| | - Mira Barda-Saad
- Mina and Everard Goodman Faculty of Life Sciences; Bar Ilan University; Ramat Gan Israel
| | - Jordan H. Chill
- Department of Chemistry; Bar Ilan University; Ramat Gan Israel
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12
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Abstract
WIP plays an important role in the remodeling of the actin cytoskeleton, which controls cellular activation, proliferation, and function. WIP regulates actin polymerization by linking the actin machinery to signaling cascades. WIP binding to WASp and to its homolog, N-WASp, which are central activators of the actin-nucleating complex Arp2/3, regulates their cellular distribution, function, and stability. By binding to WASp, WIP protects it from degradation and thus, is crucial for WASp retention. Indeed, most mutations that result in WAS, an X-linked immunodeficiency caused by defective/absent WASp activity, are located in the WIP-binding region of WASp. In addition, by binding directly to actin, WIP promotes the formation and stabilization of actin filaments. WASp-independent activities of WIP constitute a new research frontier and are discussed extensively in this article. Here, we review the current information on WIP in human and mouse systems, focusing on its associated proteins, its molecular-regulatory mechanisms, and its role as a key regulator of actin-based processes in the immune system.
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Affiliation(s)
- Sophia Fried
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Omri Matalon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Elad Noy
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Mira Barda-Saad
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
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Wiskott-Aldrich Syndrome causing mutation, Pro373Ser restricts conformational changes essential for WASP activity in T-cells. Biochim Biophys Acta Mol Basis Dis 2014; 1842:623-34. [PMID: 24440360 DOI: 10.1016/j.bbadis.2014.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 01/04/2014] [Accepted: 01/08/2014] [Indexed: 11/22/2022]
Abstract
Wiskott-Aldrich Syndrome (WAS) is caused by mutations in Wiskott-Aldrich Syndrome Protein (WASP) and majority of the mutations are found in the WASP Homology 1 (WH1) domain which mediates interaction with WIP (WASP Interacting Protein), a WASP chaperone. Two point mutations together in the proline rich region (PRR) domain of WASP (S339Y/P373S) have been reported to cause WAS however the molecular defect has not been characterized. Expression of these mutants separately (WASPR(S339Y), WASPR(P373S)) or together (WASPR(SP/YS)) did not rescue the chemotaxis defect or membrane projection defect of Jurkat(WKD) T-cells (WASP knockdown). This is not due to the inability of WASP-PRR mutants to form functional WASP-WIP complex in growth rescue experiments in las17Δ yeast strain. Expression of WASPR(S339Y) but not WASPR(P373S) or WASPR(SP/YS) rescued the IL-2 expression defect of Jurkat(WKD) T-cells, suggesting that Pro373Ser mutation alone is sufficient to inhibit WASP functions in T-cell activation. The diffused localization of WASP-PRR mutants in activated Jurkat T-cells suggests that Ser339 and Pro373 are critical for WASP localization. WASP-PRR mutations either together or individually did not abolish interaction of WASP with sixteen WASP binding proteins including Hck, however they caused reduction in Hck mediated tyrosine phosphorylation of WASP which is critical for WASP activity. The auto-inhibitory conformation of WASP(P373S) mutant was not relieved by the binding of Toca-1 or Nck1. Thus, our results suggest that Pro373Ser mutation reduces Tyr291 phosphorylation and prevents conformational changes required for WASP activity in chemotaxis and T-cell activation. Thus Pro3373Ser is probably responsible for all the defects associated with WAS in the patients.
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14
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Pankewycz O, Ambrus J, Shen L, Xuan J, Li H, Wu J, Guo LW, Feng L, Laftavi MR. Inhibiting Wipf2 downregulation by transgenic expression of its 3′ mRNA-untranslated region improves cytotoxicity and vaccination response. Eur J Immunol 2012; 42:2409-18. [PMID: 22674044 DOI: 10.1002/eji.201141533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Oleh Pankewycz
- Department of Surgery; School of Medicine and Biomedical Sciences; University at Buffalo; Buffalo; NY; USA
| | - Julian Ambrus
- Department of Medicine; School of Medicine and Biomedical Sciences; University at Buffalo; Buffalo; NY; USA
| | - Long Shen
- Department of Medicine; School of Medicine and Biomedical Sciences; University at Buffalo; Buffalo; NY; USA
| | - Jingxiu Xuan
- Department of Surgery; School of Medicine and Biomedical Sciences; University at Buffalo; Buffalo; NY; USA
| | - Hong Li
- Joint Research Center of West China Second University; Hospital of Sichuan University; Chengdu; China
| | - Jing Wu
- Department of Medicine; School of Medicine and Biomedical Sciences; University at Buffalo; Buffalo; NY; USA
| | - Li-Wu Guo
- Division of Genetic Toxicology; National Center for Toxicological Research-Food and Drug Administration; Jefferson; AR; USA
| | - Lin Feng
- Department of Surgery; School of Medicine and Biomedical Sciences; University at Buffalo; Buffalo; NY; USA
| | - Mark R. Laftavi
- Department of Surgery; School of Medicine and Biomedical Sciences; University at Buffalo; Buffalo; NY; USA
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15
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WIP remodeling actin behind the scenes: how WIP reshapes immune and other functions. Int J Mol Sci 2012; 13:7629-7647. [PMID: 22837718 PMCID: PMC3397550 DOI: 10.3390/ijms13067629] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 06/07/2012] [Accepted: 06/14/2012] [Indexed: 01/09/2023] Open
Abstract
Actin polymerization is a fundamental cellular process regulating immune cell functions and the immune response. The Wiskott-Aldrich syndrome protein (WASp) is an actin nucleation promoting factor, which is exclusively expressed in hematopoietic cells, where it plays a key regulatory role in cytoskeletal dynamics. WASp interacting protein (WIP) was first discovered as the binding partner of WASp, through the use of the yeast two hybrid system. WIP was later identified as a chaperone of WASp, necessary for its stability. Mutations occurring at the WASp homology 1 domain (WH1), which serves as the WIP binding site, were found to cause the Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT). WAS manifests as an immune deficiency characterized by eczema, thrombocytopenia, recurrent infections, and hematopoietic malignancies, demonstrating the importance of WIP for WASp complex formation and for a proper immune response. WIP deficiency was found to lead to different abnormalities in the activity of various lymphocytes, suggesting differential cell-dependent roles for WIP. Additionally, WIP deficiency causes cellular abnormalities not found in WASp-deficient cells, indicating that WIP fulfills roles beyond stabilizing WASp. Indeed, WIP was shown to interact with various binding partners, including the signaling proteins Nck, CrkL and cortactin. Recent studies have demonstrated that WIP also takes part in non immune cellular processes such as cancer invasion and metastasis, in addition to cell subversion by intracellular pathogens. Understanding of numerous functions of WIP can enhance our current understanding of activation and function of immune and other cell types.
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16
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Eriksson T, Varshney G, Aspenström P, Palmer RH. Characterisation of the role of Vrp1 in cell fusion during the development of visceral muscle of Drosophila melanogaster. BMC DEVELOPMENTAL BIOLOGY 2010; 10:86. [PMID: 20701765 PMCID: PMC2931478 DOI: 10.1186/1471-213x-10-86] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 08/11/2010] [Indexed: 12/03/2022]
Abstract
Background In Drosophila muscle cell fusion takes place both during the formation of the somatic mesoderm and the visceral mesoderm, giving rise to the skeletal muscles and the gut musculature respectively. The core process of myoblast fusion is believed to be similar for both organs. The actin cytoskeleton regulator Verprolin acts by binding to WASP, which in turn binds to the Arp2/3 complex and thus activates actin polymerization. While Verprolin has been shown to be important for somatic muscle cell fusion, the function of this protein in visceral muscle fusion has not been determined. Results Verprolin is specifically expressed in the fusion competent myoblasts of the visceral mesoderm, suggesting a role in visceral mesoderm fusion. We here describe a novel Verprolin mutant allele which displays subtle visceral mesoderm fusion defects in the form of mislocalization of the immunoglobulin superfamily molecule Duf/Kirre, which is required on the myoblast cell surface to facilitate attachment between cells that are about to fuse, indicating a function for Verprolin in visceral mesoderm fusion. We further show that Verprolin mutant cells are capable of both migrating and fusing and that the WASP-binding domain of Verprolin is required for rescue of the Verprolin mutant phenotype. Conclusions Verprolin is expressed in the visceral mesoderm and plays a role in visceral muscle fusion as shown by mislocalization of Duf/Kirre in the Verprolin mutant, however it is not absolutely required for myoblast fusion in either the visceral or the somatic mesoderm.
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Affiliation(s)
- Therese Eriksson
- Department of Molecular Biology, Building 6L, Umeå University, Umeå S-90187, Sweden
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17
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Misra A, Rajmohan R, Lim RPZ, Bhattacharyya S, Thanabalu T. The mammalian verprolin, WIRE induces filopodia independent of N-WASP through IRSp53. Exp Cell Res 2010; 316:2810-24. [PMID: 20678498 DOI: 10.1016/j.yexcr.2010.07.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Revised: 07/23/2010] [Accepted: 07/24/2010] [Indexed: 10/19/2022]
Abstract
The mammalian verprolin family of proteins, WIP (WASP Interacting Protein), CR16 (Corticoid Regulated) and WIRE (WIp-RElated) regulate the actin cytoskeleton through WASP/N-WASP (Wiskott Aldrich Syndrome Protein and Neural-WASP). In order to characterize the WASP/N-WASP-independent function of WIRE, we screened and identified IRSp53 (Insulin Receptor Substrate) as a WIRE interacting protein. Expression of IRSp53 with WIRE in N-WASP(-/-) mouse fibroblast cells induced filopodia while co-expression of IRSp53 with WIP did not. The induction of filopodia is dependent on WIRE-IRSp53 interaction as mutation in the SH3 domain of IRSp53 abolished WIRE-IRSp53 interaction as well as the ability to induce filopodia. Similarly, the Verprolin (V)-domain of WIRE is critical for IRSp53-WIRE interaction and for filopodia formation. The interaction between WIRE and IRSp53 is regulated by Cdc42 as mutations which abolish Cdc42-IRSp53 interaction lead to loss of IRSp53-WIRE interaction as shown by pull down assay. The plasma membrane localization of IRSp53 is dependent on Cdc42 and WIRE. Expression of Cdc42(G12V) (active mutant) with WIRE-IRSp53 caused significant increase in the number of filopodia per cell. Thus our results show that Cdc42 regulates the activity of IRSp53 by regulating the IRSp53-WIRE interaction as well as localization of the complex to plasma membrane to generate filopodia.
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Affiliation(s)
- Ashish Misra
- School of Biological Sciences, Nanyang Technological University, Singapore, Republic of Singapore
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18
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The formin-homology protein SmDia interacts with the Src kinase SmTK and the GTPase SmRho1 in the gonads of Schistosoma mansoni. PLoS One 2009; 4:e6998. [PMID: 19746159 PMCID: PMC2734992 DOI: 10.1371/journal.pone.0006998] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 07/27/2009] [Indexed: 01/13/2023] Open
Abstract
Background Schistosomiasis (bilharzia) is a parasitic disease of worldwide significance affecting human and animals. As schistosome eggs are responsible for pathogenesis, the understanding of processes controlling gonad development might open new perspectives for intervention. The Src-like tyrosine-kinase SmTK3 of Schistosoma mansoni is expressed in the gonads, and its pharmacological inhibition reduces mitogenic activity and egg production in paired females in vitro. Since Src kinases are important signal transduction proteins it is of interest to unravel the signaling cascades SmTK3 is involved in to understand its cellular role in the gonads. Methodology and Results Towards this end we established and screened a yeast two-hybrid (Y2H) cDNA library of adult S. mansoni with a bait construct encoding the SH3 (src homology) domain and unique site of SmTK3. Among the binding partners found was a diaphanous homolog (SmDia), which was characterized further. SmDia is a single-copy gene transcribed throughout development with a bias towards male transcription. Its deduced amino acid sequence reveals all diaphanous-characteristic functional domains. Binding studies with truncated SmDia clones identified SmTK3 interaction sites demonstrating that maximal binding efficiency depends on the N-terminal part of the FH1 (formin homology) domain and the inter-domain region of SmDia located upstream of FH1 in combination with the unique site and the SH3 domain of SmTK3, respectively. SmDia also directly interacted with the GTPase SmRho1 of S. mansoni. In situ hybridization experiments finally demonstrated that SmDia, SmRho1, and SmTK3 are transcribed in the gonads of both genders. Conclusion These data provide first evidence for the existence of two cooperating pathways involving Rho and Src that bridge at SmDia probably organizing cytoskeletal events in the reproductive organs of a parasite, and beyond that in gonads of eukaryotes. Furthermore, the FH1 and inter domain region of SmDia have been discovered as binding sites for the SH3 and unique site domains of SmTK3, respectively.
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19
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Munn AL, Thanabalu T. Verprolin: A cool set of actin-binding sites and some very HOT prolines. IUBMB Life 2009; 61:707-12. [DOI: 10.1002/iub.195] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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20
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Lai FPL, Szczodrak M, Oelkers JM, Ladwein M, Acconcia F, Benesch S, Auinger S, Faix J, Small JV, Polo S, Stradal TEB, Rottner K. Cortactin promotes migration and platelet-derived growth factor-induced actin reorganization by signaling to Rho-GTPases. Mol Biol Cell 2009; 20:3209-23. [PMID: 19458196 DOI: 10.1091/mbc.e08-12-1180] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Dynamic actin rearrangements are initiated and maintained by actin filament nucleators, including the Arp2/3-complex. This protein assembly is activated in vitro by distinct nucleation-promoting factors such as Wiskott-Aldrich syndrome protein/Scar family proteins or cortactin, but the relative in vivo functions of each of them remain controversial. Here, we report the conditional genetic disruption of murine cortactin, implicated previously in dynamic actin reorganizations driving lamellipodium protrusion and endocytosis. Unexpectedly, cortactin-deficient cells showed little changes in overall cell morphology and growth. Ultrastructural analyses and live-cell imaging studies revealed unimpaired lamellipodial architecture, Rac-induced protrusion, and actin network turnover, although actin assembly rates in the lamellipodium were modestly increased. In contrast, platelet-derived growth factor-induced actin reorganization and Rac activation were impaired in cortactin null cells. In addition, cortactin deficiency caused reduction of Cdc42 activity and defects in random and directed cell migration. Reduced migration of cortactin null cells could be restored, at least in part, by active Rac and Cdc42 variants. Finally, cortactin removal did not affect the efficiency of receptor-mediated endocytosis. Together, we conclude that cortactin is fully dispensable for Arp2/3-complex activation during lamellipodia protrusion or clathrin pit endocytosis. Furthermore, we propose that cortactin promotes cell migration indirectly, through contributing to activation of selected Rho-GTPases.
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Affiliation(s)
- Frank P L Lai
- Cytoskeleton Dynamics Group, Helmholtz Centre for Infection Research, D-38124 Braunschweig, Germany
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21
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Peterson FC, Volkman BF. Diversity of polyproline recognition by EVH1 domains. Front Biosci (Landmark Ed) 2009; 14:833-46. [PMID: 19273103 DOI: 10.2741/3281] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Enabled/VASP Homology-1 (EVH1) domains function primarily as interaction modules that link signaling proteins by binding to proline-rich sequences. EVH1 domains are ~115 residues in length and adopt the pleckstrin homology (PH) fold. Four different protein families contain EVH1 domains: Ena/VASP, Homer, WASP and SPRED. Except for the SPRED domains, for which no binding partners are known, EVH1 domains use a conserved hydrophobic cleft to bind a four-residue motif containing 2-4 prolines. Conserved aromatic residues, including an invariant tryptophan, create a wedge-shaped groove on the EVH1 surface that matches the triangular profile of a polyproline type II helix. Hydrophobic residues adjacent to the polyproline motif dock into complementary sites on the EVH1 domain to enhance ligand binding specificity. Pseudosymmetry in the polyproline type II helix allows peptide ligands to bind in either of two N-to-C terminal orientations, depending on interactions between sequences flanking the prolines and the EVH1 domain. EVH1 domains also recognize non-proline motifs, as illustrated by the structure of an EVH1:LIM3 complex and the extended EVH1 ligands of the verprolin family.
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Affiliation(s)
- Francis C Peterson
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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22
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Abstract
Myoblasts in vitro form characteristic arrays of bipolar-shaped cells prior to fusion. We have shown that the actin cytoskeleton re-organizes in these fusing cells and that the interaction of non-muscle myosin 2A with actin at the plasma membrane helps to generate the bipolar shape of myoblasts, which is key for fusion. Here we discuss how fusion occurs, and in particular how the actin cytoskeleton is involved. Myoblast fusion is essential to form the multi-nucleated muscle fibres that make up the skeletal muscle. Skeletal muscle fibres contain many nuclei, roughly one nucleus to every 15 sarcomeres (35 microm) in adult muscle, although this varies with muscle type (Bruusgaard et al., 2006). Thus a muscle fibre 30 cm long contains about 8000 nuclei and is formed by the fusion of about 8000 cells during development. The formation of multi-nucleated myotubes has been intensively studied for many years using a number of different systems. Many different proteins have been identified using Drosophila as a model system (e.g. see reviews by Taylor, 2000, 2002) that have given an insight into what happens in mammals. However, the process of fusion of mammalian cells is less well understood, and this paper will cover some of the aspects of mammalian myoblast fusion, with a particular focus on the role of the actin cytoskeleton.
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Affiliation(s)
- M Peckham
- Institute of Cellular and Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
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23
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Berger S, Schäfer G, Kesper DA, Holz A, Eriksson T, Palmer RH, Beck L, Klämbt C, Renkawitz-Pohl R, Onel SF. WASP and SCAR have distinct roles in activating the Arp2/3 complex during myoblast fusion. J Cell Sci 2008; 121:1303-13. [PMID: 18388318 DOI: 10.1242/jcs.022269] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Myoblast fusion takes place in two steps in mammals and in Drosophila. First, founder cells (FCs) and fusion-competent myoblasts (FCMs) fuse to form a trinucleated precursor, which then recruits further FCMs. This process depends on the formation of the fusion-restricted myogenic-adhesive structure (FuRMAS), which contains filamentous actin (F-actin) plugs at the sites of cell contact. Fusion relies on the HEM2 (NAP1) homolog Kette, as well as Blow and WASP, a member of the Wiskott-Aldrich-syndrome protein family. Here, we show the identification and characterization of schwächling--a new Arp3-null allele. Ultrastructural analyses demonstrate that Arp3 schwächling mutants can form a fusion pore, but fail to integrate the fusing FCM. Double-mutant experiments revealed that fusion is blocked completely in Arp3 and wasp double mutants, suggesting the involvement of a further F-actin regulator. Indeed, double-mutant analyses with scar/WAVE and with the WASP-interacting partner vrp1 (sltr, wip)/WIP show that the F-actin regulator scar also controls F-actin formation during myoblast fusion. Furthermore, the synergistic phenotype observed in Arp3 wasp and in scar vrp1 double mutants suggests that WASP and SCAR have distinct roles in controlling F-actin formation. From these findings we derived a new model for actin regulation during myoblast fusion.
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Affiliation(s)
- Susanne Berger
- Fachbereich Biologie, Entwicklungsbiologie, Philipps-Universität Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany
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24
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Aspenström P. Roles of F-BAR/PCH proteins in the regulation of membrane dynamics and actin reorganization. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 272:1-31. [PMID: 19121815 DOI: 10.1016/s1937-6448(08)01601-8] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The Pombe Cdc15 Homology (PCH) proteins have emerged in many species as important coordinators of signaling pathways that regulate actomyosin assembly and membrane dynamics. The hallmark of the PCH proteins is the presence of a Fes/CIP4 homology-Bin/Amphiphysin/Rvsp (F-BAR) domain; therefore they are commonly referred to as F-BAR proteins. The prototype F-BAR protein, Cdc15p of Schizosaccharomyces pombe, has a role in the formation of the contractile actomyosin ring during cytokinesis. Vertebrate F-BAR proteins have an established role in binding phospholipids and they participate in membrane deformations, for instance, during the internalization of transmembrane receptors. This way the F-BAR proteins will function as linkers between the actin polymerization apparatus and the machinery regulating membrane dynamics. Interestingly, some members of the F-BAR proteins are implicated in inflammatory or neurodegenerative disorders and the observations can be expected to have clinical implications for the treatment of the diseases.
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Affiliation(s)
- Pontus Aspenström
- Ludwig Institute for Cancer Research, Uppsala University, SE-751 24 Uppsala, Sweden
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25
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Misra A, Lim RPZ, Wu Z, Thanabalu T. N-WASP plays a critical role in fibroblast adhesion and spreading. Biochem Biophys Res Commun 2007; 364:908-12. [PMID: 17963692 DOI: 10.1016/j.bbrc.2007.10.086] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Accepted: 10/17/2007] [Indexed: 11/16/2022]
Abstract
N-WASP (Neural Wiskott Aldrich Syndrome Protein) regulates actin polymerization by activating the Arp2/3 complex and promotes the formation of actin-rich structures such as filopodia. Such actin-rich structures play critical roles in cell adhesion and cell motility. Analysis of the adhesion properties of N-WASP+/+ and N-WASP-/- mouse embryonic fibroblasts to extracellular matrix proteins revealed that N-WASP is critical for cell adhesion to fibronectin. There was no significant difference in the localization of paxillin in the two cell lines, however the vinculin patches in WASP+/+ cells were thicker and more prominent than those in N-WASP-/- cells. The beta1 integrins in N-WASP+/+ cells were found in large clusters, while beta1 integrins were more dispersed in N-WASP-/- cells. The N-WASP-/- cells migrated more rapidly than N-WASP+/+ cells in a scratch migration assay. Thus, our data suggest that N-WASP deficiency leads to reduced adhesion to fibronectin and increased cell motility.
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Affiliation(s)
- Ashish Misra
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Republic of Singapore
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26
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Halbleib JM, Sääf AM, Brown PO, Nelson WJ. Transcriptional modulation of genes encoding structural characteristics of differentiating enterocytes during development of a polarized epithelium in vitro. Mol Biol Cell 2007; 18:4261-78. [PMID: 17699590 PMCID: PMC2043570 DOI: 10.1091/mbc.e07-04-0308] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although there is considerable evidence implicating posttranslational mechanisms in the development of epithelial cell polarity, little is known about the patterns of gene expression and transcriptional regulation during this process. We characterized the temporal program of gene expression during cell-cell adhesion-initiated polarization of human Caco-2 cells in tissue culture, which develop structural and functional polarity similar to that of enterocytes in vivo. A distinctive switch in gene expression patterns occurred upon formation of cell-cell contacts between neighboring cells. Expression of genes involved in cell proliferation was down-regulated concomitant with induction of genes necessary for functional specialization of polarized epithelial cells. Transcriptional up-regulation of these latter genes correlated with formation of important structural and functional features in enterocyte differentiation and establishment of structural and functional cell polarity; components of the apical microvilli were induced as the brush border formed during polarization; as barrier function was established, expression of tight junction transmembrane proteins peaked; transcripts encoding components of the apical, but not the basal-lateral trafficking machinery were increased during polarization. Coordinated expression of genes encoding components of functional cell structures were often observed indicating temporal control of expression and assembly of multiprotein complexes.
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Affiliation(s)
| | | | - Patrick O. Brown
- Biochemistry, and
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305
| | - W. James Nelson
- Departments of *Molecular and Cellular Physiology
- Biological Sciences and
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27
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Thanabalu T, Rajmohan R, Meng L, Ren G, Vajjhala PR, Munn AL. Verprolin function in endocytosis and actin organization. FEBS J 2007; 274:4103-25. [PMID: 17635585 DOI: 10.1111/j.1742-4658.2007.05936.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vrp1p (verprolin, End5p) is the yeast ortholog of human Wiskott-Aldrich syndrome protein (WASP)-interacting protein (WIP). Vrp1p localizes to the cortical actin cytoskeleton, is necessary for its polarization to sites of growth and is also essential for endocytosis. At elevated temperature, Vrp1p becomes essential for growth. A C-terminal Vrp1p fragment (C-Vrp1p) retains the ability to localize to the cortical actin cytoskeleton and function in actin-cytoskeleton polarization, endocytosis and growth. Here, we demonstrate that two submodules in C-Vrp1p are required for actin-cytoskeleton polarization: a novel C-terminal actin-binding submodule (CABS) that contains a novel G-actin-binding domain, which we call a verprolin homology 2 C-terminal (VH2-C) domain; and a second submodule comprising the Las17p-binding domain (LBD) that binds Las17p (yeast WASP). The LBD localizes C-Vrp1p to membranes and the cortical actin cytoskeleton. Intriguingly, the LBD is sufficient to restore endocytosis and growth at elevated temperature to Vrp1p-deficient cells. The CABS also restores these functions, but only if modified by a lipid anchor to provide membrane association. Our findings highlight the role of Las17p binding for Vrp1p membrane association, suggest general membrane association may be more important than specific targeting to the cortical actin cytoskeleton for Vrp1p function in endocytosis and cell growth, and suggest that Vrp1p binding to individual effectors may alter their physiological activity.
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Affiliation(s)
- Thirumaran Thanabalu
- Institute of Molecular and Cell Biology, A*STAR Biomedical Science Institutes, Singapore
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28
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Massarwa R, Carmon S, Shilo BZ, Schejter ED. WIP/WASp-based actin-polymerization machinery is essential for myoblast fusion in Drosophila. Dev Cell 2007; 12:557-69. [PMID: 17419994 DOI: 10.1016/j.devcel.2007.01.016] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Revised: 01/16/2007] [Accepted: 01/25/2007] [Indexed: 11/19/2022]
Abstract
Formation of syncytial muscle fibers involves repeated rounds of cell fusion between growing myotubes and neighboring myoblasts. We have established that Wsp, the Drosophila homolog of the WASp family of microfilament nucleation-promoting factors, is an essential facilitator of myoblast fusion in Drosophila embryos. D-WIP, a homolog of the conserved Verprolin/WASp Interacting Protein family of WASp-binding proteins, performs a key mediating role in this context. D-WIP, which is expressed specifically in myoblasts, associates with both the WASp-Arp2/3 system and with the myoblast adhesion molecules Dumbfounded and Sticks and Stones, thereby recruiting the actin-polymerization machinery to sites of myoblast attachment and fusion. Our analysis demonstrates that this recruitment is normally required late in the fusion process, for enlargement of nascent fusion pores and breakdown of the apposed cell membranes. These observations identify cellular and developmental roles for the WASp-Arp2/3 pathway, and provide a link between force-generating actin polymerization and cell fusion.
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Affiliation(s)
- R'ada Massarwa
- Department of Molecular Genetics, Weizmann Institute of Science, 76100 Rehovot, Israel
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29
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Meng L, Rajmohan R, Yu S, Thanabalu T. Actin binding and proline rich motifs of CR16 play redundant role in growth of vrp1Delta cells. Biochem Biophys Res Commun 2007; 357:289-94. [PMID: 17418095 DOI: 10.1016/j.bbrc.2007.03.144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Accepted: 03/22/2007] [Indexed: 11/20/2022]
Abstract
CR16, (Glucocorticoid-regulated) belongs to the verprolin family of proteins which are characterized by the presence of a V domain (verprolin) at the N-terminal. Expression of CR16 suppressed the growth and endocytosis defect of vrp1Delta strain without correcting the actin patch polarization defect. The V domain of CR16 is critical for suppression of the growth defect of vrp1Delta strain but not for localisation to cortical actin patches. Mutations in the actin binding motif alone did not abolish the activity of CR16 but the mutations in combination with deletion of N-terminal proline rich motif abolished the ability of CR16 to suppress the growth defect. This suggests that the V domain of CR16 has two functionally redundant motifs and either one of these motifs is sufficient for suppressing the growth defect of vrp1Delta strain. This is in contrast to the observation that both WIP and WIRE require the actin binding motif for their activity.
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Affiliation(s)
- Lei Meng
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Republic of Singapore
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30
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Peterson FC, Deng Q, Zettl M, Prehoda KE, Lim WA, Way M, Volkman BF. Multiple WASP-interacting protein recognition motifs are required for a functional interaction with N-WASP. J Biol Chem 2007; 282:8446-53. [PMID: 17229736 DOI: 10.1074/jbc.m609902200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The WASP-interacting protein (WIP) targets WASP/WAVE proteins through a constitutive interaction with an amino-terminal enabled/VASP homology (EVH1) domain. Parallel investigations had previously identified two distinct N-WASP binding motifs corresponding to WIP residues 451-461 and 461-485, and we determined the structure of a complex between WIP-(461-485) and the N-WASP EVH1 domain (Volkman, B. F., Prehoda, K. E., Scott, J. A., Peterson, F. C., and Lim, W. A. (2002) Cell 111, 565-576). The present results show that, when combined, the WIP-(451-485) sequence wraps further around the EVH1 domain, extending the interface observed previously. Specific contacts with three WIP epitopes corresponded to regions of high sequence conservation in the verprolin family. A central polyproline motif occupied the canonical binding site but in a reversed orientation relative to other EVH1 complexes. This interaction was augmented in the amino- and carboxyl-terminal directions by additional hydrophobic contacts involving WIP residues 454-459 and 475-478, respectively. Disruption of any of the three WIP epitopes reduced N-WASP binding in cells, demonstrating a functional requirement for the entire binding domain, which is significantly longer than the polyproline motifs recognized by other EVH1 domains.
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Affiliation(s)
- Francis C Peterson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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31
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Willard FS. Does WAVE1 contain a GoLoco/GPR motif? Int J Biol Sci 2006; 2:194-6. [PMID: 16896366 PMCID: PMC1525215 DOI: 10.7150/ijbs.2.194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Accepted: 07/19/2006] [Indexed: 11/05/2022] Open
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Sasaki AT, Firtel RA. Regulation of chemotaxis by the orchestrated activation of Ras, PI3K, and TOR. Eur J Cell Biol 2006; 85:873-95. [PMID: 16740339 DOI: 10.1016/j.ejcb.2006.04.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Directed cell migration and cell polarity are crucial in many facets of biological processes. Cellular motility requires a complex array of signaling pathways, in which orchestrated cross-talk, a feedback loop, and multi-component signaling recur. Almost every signaling molecule requires several regulatory processes to be functionally activated, and a lack of a signaling molecule often leads to chemotaxis defects, suggesting an integral role for each component in the pathway. We outline our current understanding of the signaling event that regulates chemotaxis with an emphasis on recent findings associated with the Ras, PI3K, and target of rapamycin (TOR) pathways and the interplay of these pathways. Ras, PI3K, and TOR are known as key regulators of cellular growth. Deregulation of those pathways is associated with many human diseases, such as cancer, developmental disorders, and immunological deficiency. Recent studies in yeast, mammalian cells, and Dictyostelium discoideum reveal another critical role of Ras, PI3K, and TOR in regulating the actin cytoskeleton, cell polarity, and cellular movement. These findings shed light on the mechanism by which eukaryotic cells maintain cell polarity and directed cell movement, and also demonstrate that multiple steps in the signal transduction pathway coordinately regulate cell motility.
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Affiliation(s)
- Atsuo T Sasaki
- Section of Cell and Developmental Biology, Division of Biological Sciences, Center for Molecular Genetics, University of California, San Diego, Natural Sciences Building, Room 6316, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA
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