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Romero MD, Carabeo RA. Distinct roles of the Chlamydia trachomatis effectors TarP and TmeA in the regulation of formin and Arp2/3 during entry. J Cell Sci 2022; 135:jcs260185. [PMID: 36093837 PMCID: PMC9659389 DOI: 10.1242/jcs.260185] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 09/05/2022] [Indexed: 12/13/2022] Open
Abstract
The obligate intracellular pathogen Chlamydia trachomatis manipulates the host actin cytoskeleton to assemble actin-rich structures that drive pathogen entry. The recent discovery of TmeA, which, like TarP, is an invasion-associated type III effector implicated in actin remodeling, raised questions regarding the nature of their functional interaction. Quantitative live-cell imaging of actin remodeling at invasion sites revealed differences in recruitment and turnover kinetics associated with the TarP and TmeA pathways, with the former accounting for most of the robust actin dynamics at invasion sites. TarP-mediated recruitment of actin nucleators, i.e. formins and the Arp2/3 complex, was crucial for rapid actin kinetics, generating a collaborative positive feedback loop that enhanced their respective actin-nucleating activities within invasion sites. In contrast, the formin Fmn1 was not recruited to invasion sites and did not collaborate with Arp2/3 within the context of TmeA-associated actin recruitment. Although the TarP-Fmn1-Arp2/3 signaling axis is responsible for the majority of actin dynamics, its inhibition had similar effects as the deletion of TmeA on invasion efficiency, consistent with the proposed model that TarP and TmeA act on different stages of the same invasion pathway.
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Affiliation(s)
- Matthew D. Romero
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, NE 68198-5900, USA
| | - Rey A. Carabeo
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, NE 68198-5900, USA
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2
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Velle KB, Campellone KG. Enteropathogenic E. coli relies on collaboration between the formin mDia1 and the Arp2/3 complex for actin pedestal biogenesis and maintenance. PLoS Pathog 2018; 14:e1007485. [PMID: 30550556 PMCID: PMC6310289 DOI: 10.1371/journal.ppat.1007485] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 12/28/2018] [Accepted: 11/23/2018] [Indexed: 12/16/2022] Open
Abstract
Enteropathogenic and enterohemorrhagic E. coli (EPEC and EHEC) are closely related extracellular pathogens that reorganize host cell actin into “pedestals” beneath the tightly adherent bacteria. This pedestal-forming activity is both a critical step in pathogenesis, and it makes EPEC and EHEC useful models for studying the actin rearrangements that underlie membrane protrusions. To generate pedestals, EPEC relies on the tyrosine phosphorylated bacterial effector protein Tir to bind host adaptor proteins that recruit N-WASP, a nucleation-promoting factor that activates the Arp2/3 complex to drive actin polymerization. In contrast, EHEC depends on the effector EspFU to multimerize N-WASP and promote Arp2/3 activation. Although these core pathways of pedestal assembly are well-characterized, the contributions of additional actin nucleation factors are unknown. We investigated potential cooperation between the Arp2/3 complex and other classes of nucleators using chemical inhibitors, siRNAs, and knockout cell lines. We found that inhibition of formins impairs actin pedestal assembly, motility, and cellular colonization for bacteria using the EPEC, but not the EHEC, pathway of actin polymerization. We also identified mDia1 as the formin contributing to EPEC pedestal assembly, as its expression level positively correlates with the efficiency of pedestal formation, and it localizes to the base of pedestals both during their initiation and once they have reached steady state. Collectively, our data suggest that mDia1 enhances EPEC pedestal biogenesis and maintenance by generating seed filaments to be used by the N-WASP-Arp2/3-dependent actin nucleation machinery and by sustaining Src-mediated phosphorylation of Tir. Microbial pathogens that rearrange the host actin cytoskeleton have made valuable contributions to our understanding of cell signaling and movement. The assembly and organization of the actin cytoskeleton is driven by proteins called nucleators, which can be manipulated by bacteria including enteropathogenic Escherichia coli (EPEC), a frequent cause of pediatric diarrhea in developing countries. After ingestion, EPEC adhere tightly to cells of the intestine and hijack the underlying cytoskeleton to create protrusions called actin pedestals. While mechanisms of pedestal assembly involving a nucleator called the Arp2/3 complex have been defined for EPEC, the contribution of additional host nucleators has not been determined. We assessed the roles of several actin nucleators in EPEC pedestals and found that in addition to Arp2/3 complex-mediated nucleation, the formin mDia1 is a key contributor to actin assembly. These findings highlight the importance of nucleator collaboration in pathogenesis, and also advance our understanding of the molecular and cellular basis of EPEC infection, which is ultimately important for the discovery of new drug targets.
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Affiliation(s)
- Katrina B. Velle
- Department of Molecular and Cell Biology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, United States of America
| | - Kenneth G. Campellone
- Department of Molecular and Cell Biology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, United States of America
- * E-mail:
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3
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Unconventional actins and actin-binding proteins in human protozoan parasites. Int J Parasitol 2015; 45:435-47. [DOI: 10.1016/j.ijpara.2015.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 12/19/2014] [Accepted: 01/27/2015] [Indexed: 12/11/2022]
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4
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Zahiri J, Mohammad-Noori M, Ebrahimpour R, Saadat S, Bozorgmehr JH, Goldberg T, Masoudi-Nejad A. LocFuse: human protein-protein interaction prediction via classifier fusion using protein localization information. Genomics 2014; 104:496-503. [PMID: 25458812 DOI: 10.1016/j.ygeno.2014.10.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 09/28/2014] [Accepted: 10/02/2014] [Indexed: 12/20/2022]
Abstract
UNLABELLED Protein-protein interaction (PPI) detection is one of the central goals of functional genomics and systems biology. Knowledge about the nature of PPIs can help fill the widening gap between sequence information and functional annotations. Although experimental methods have produced valuable PPI data, they also suffer from significant limitations. Computational PPI prediction methods have attracted tremendous attentions. Despite considerable efforts, PPI prediction is still in its infancy in complex multicellular organisms such as humans. Here, we propose a novel ensemble learning method, LocFuse, which is useful in human PPI prediction. This method uses eight different genomic and proteomic features along with four types of different classifiers. The prediction performance of this classifier selection method was found to be considerably better than methods employed hitherto. This confirms the complex nature of the PPI prediction problem and also the necessity of using biological information for classifier fusion. The LocFuse is available at: http://lbb.ut.ac.ir/Download/LBBsoft/LocFuse. BIOLOGICAL SIGNIFICANCE The results revealed that if we divide proteome space according to the cellular localization of proteins, then the utility of some classifiers in PPI prediction can be improved. Therefore, to predict the interaction for any given protein pair, we can select the most accurate classifier with regard to the cellular localization information. Based on the results, we can say that the importance of different features for PPI prediction varies between differently localized proteins; however in general, our novel features, which were extracted from position-specific scoring matrices (PSSMs), are the most important ones and the Random Forest (RF) classifier performs best in most cases. LocFuse was developed with a user-friendly graphic interface and it is freely available for Linux, Mac OSX and MS Windows operating systems.
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Affiliation(s)
- Javad Zahiri
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Morteza Mohammad-Noori
- School of Mathematics, Statistics and Computer Science, College of Science, University of Tehran, Tehran, Iran
| | - Reza Ebrahimpour
- Brain and Intelligent Systems Research Lab, Department of Electrical and Computer Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran
| | - Samaneh Saadat
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Joseph H Bozorgmehr
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Tatyana Goldberg
- Department for Bioinformatics and Computational Biology, Faculty of Informatics, TUM, Garching 85748, Germany
| | - Ali Masoudi-Nejad
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
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5
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Cvrčková F. Formins and membranes: anchoring cortical actin to the cell wall and beyond. FRONTIERS IN PLANT SCIENCE 2013; 4:436. [PMID: 24204371 PMCID: PMC3817587 DOI: 10.3389/fpls.2013.00436] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 10/13/2013] [Indexed: 05/03/2023]
Abstract
Formins are evolutionarily conserved eukaryotic proteins participating in actin and microtubule organization. Land plants have three formin clades, with only two - Class I and II - present in angiosperms. Class I formins are often transmembrane proteins, residing at the plasmalemma and anchoring the cortical cytoskeleton across the membrane to the cell wall, while Class II formins possess a PTEN-related membrane-binding domain. Lower plant Class III and non-plant formins usually contain domains predicted to bind RHO GTPases that are membrane-associated. Thus, some kind of membrane anchorage appears to be a common formin feature. Direct interactions between various non-plant formins and integral or peripheral membrane proteins have indeed been reported, with varying mechanisms and biological implications. Besides of summarizing new data on Class I and Class II formin-membrane relationships, this review surveys such "non-classical" formin-membrane interactions and examines which, if any, of them may be evolutionarily conserved and operating also in plants. FYVE, SH3 and BAR domain-containing proteins emerge as possible candidates for such conserved membrane-associated formin partners.
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Affiliation(s)
- Fatima Cvrčková
- *Correspondence: Fatima Cvrčková, Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, CZ 128 43, Prague, Czech Republic e-mail:
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Levi M, Ninio-Mani L, Shalgi R. Src protein kinases in mouse and rat oocytes and embryos. Results Probl Cell Differ 2012; 55:93-106. [PMID: 22918802 DOI: 10.1007/978-3-642-30406-4_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Meiosis of the mammalian oocytes is a specialized cell division, initiated during the female's embryonic life. It arrests at the germinal vesicle (GV) stage and resumes with GV breakdown, followed by segregation of the chromosomes and extrusion of the first polar body in an asymmetric cell division that concludes the first meiotic division, before arresting at metaphase of the second meiotic division (MII). Once fertilized, the oocyte exits from MII, extrudes the second polar body, and the developing zygote will continue dividing to create a blastocyst. Although the two processes of meiosis and mitosis have different developmental functions, it is believed that they share similar mechanisms. Src family kinases (SFKs) are nine non-receptor protein tyrosine kinases that regulate many key cellular functions including meiotic and mitotic cell cycles. In this review we discuss the involvement of SFKs in meiotic and mitotic cell cycle key processes as nuclear envelope breakdown, spindle stabilization, karyokinetic exit from metaphase, regulation of cortical actin, and cytokinetic cleavage furrow ingression.
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Affiliation(s)
- Mattan Levi
- Department of Cell and Developmental Biology, Tel Aviv University, Ramat-Aviv, Tel-Aviv, Israel
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7
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Levi M, Kaplan-Kraicer R, Shalgi R. Regulation of division in mammalian oocytes: implications for polar body formation. Mol Hum Reprod 2011; 17:328-34. [DOI: 10.1093/molehr/gar025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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8
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Young KG, Copeland JW. Formins in cell signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:183-90. [PMID: 18977250 DOI: 10.1016/j.bbamcr.2008.09.017] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2008] [Revised: 06/20/2008] [Accepted: 09/26/2008] [Indexed: 12/11/2022]
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9
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Chesarone MA, DuPage AG, Goode BL. Unleashing formins to remodel the actin and microtubule cytoskeletons. Nat Rev Mol Cell Biol 2009; 11:62-74. [PMID: 19997130 DOI: 10.1038/nrm2816] [Citation(s) in RCA: 394] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Formins are highly conserved proteins that have essential roles in remodelling the actin and microtubule cytoskeletons to influence eukaryotic cell shape and behaviour. Recent work has identified numerous cellular factors that locally recruit, activate or inactivate formins to bridle and unleash their potent effects on actin nucleation and elongation. The effects of formins on microtubules have also begun to be described, which places formins in a prime position to coordinate actin and microtubule dynamics. The emerging complexity in the mechanisms governing formins mirrors the wide range of essential functions that they perform in cell motility, cell division and cell and tissue morphogenesis.
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Affiliation(s)
- Melissa A Chesarone
- Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
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10
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Aspenström P. Formin-binding proteins: modulators of formin-dependent actin polymerization. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1803:174-82. [PMID: 19589360 DOI: 10.1016/j.bbamcr.2009.06.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 06/22/2009] [Accepted: 06/26/2009] [Indexed: 12/27/2022]
Abstract
Formins represent a major branch of actin nucleators along with the Arp2/3 complex, Spire and Cordon-bleu. Formin-mediated actin nucleation requires the formin homology 2 domain and, although the nucleation per se does not require additional factors, formin-binding proteins have been shown to be essential for the regulation of formin-dependent actin assembly in vivo. This regulation could be accomplished by formin-binding proteins being directly involved in formin-driven actin nucleation, by formin-binding proteins influencing the activated state of the formins, by linking formin-driven actin polymerization to Arp2/3 driven actin polymerization, or by influencing the subcellular localization of the formins. This review article will focus on mammalian formin-binding proteins and their roles during vital cellular processes, such as cell migration, cell division and intracellular trafficking.
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Affiliation(s)
- Pontus Aspenström
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden.
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11
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Destaing O, Sanjay A, Itzstein C, Horne WC, Toomre D, De Camilli P, Baron R. The tyrosine kinase activity of c-Src regulates actin dynamics and organization of podosomes in osteoclasts. Mol Biol Cell 2007; 19:394-404. [PMID: 17978100 DOI: 10.1091/mbc.e07-03-0227] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Podosomes are dynamic actin-rich structures composed of a dense F-actin core surrounded by a cloud of more diffuse F-actin. Src performs one or more unique functions in osteoclasts (OCLs), and podosome belts and bone resorption are impaired in the absence of Src. Using Src(-/-) OCLs, we investigated the specific functions of Src in the organization and dynamics of podosomes. We found that podosome number and the podosome-associated actin cloud were decreased in Src(-/-) OCLs. Videomicroscopy and fluorescence recovery after photobleaching analysis revealed that the life span of Src(-/-) podosomes was increased fourfold and that the rate of actin flux in the core was decreased by 40%. Thus, Src regulates the formation, structure, life span, and rate of actin polymerization in podosomes and in the actin cloud. Rescue of Src(-/-) OCLs with Src mutants showed that both the kinase activity and either the SH2 or the SH3 binding domain are required for Src to restore normal podosome organization and dynamics. Moreover, inhibition of Src family kinase activities in Src(-/-) OCLs by Src inhibitors or by expressing dominant-negative Src(K295M) induced the formation of abnormal podosomes. Thus, Src is an essential regulator of podosome structure, dynamics and organization.
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Affiliation(s)
- Olivier Destaing
- Department of Orthopaedics, Yale University School of Medicine, New Haven, CT 06520, USA
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12
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Wallar BJ, Deward AD, Resau JH, Alberts AS. RhoB and the mammalian Diaphanous-related formin mDia2 in endosome trafficking. Exp Cell Res 2006; 313:560-71. [PMID: 17198702 DOI: 10.1016/j.yexcr.2006.10.033] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2006] [Revised: 10/11/2006] [Accepted: 10/31/2006] [Indexed: 11/28/2022]
Abstract
Rho GTPases and the dynamic assembly and disassembly of actin filaments have been shown to have critical roles in both the internalization and trafficking of growth factor receptors. While all three mammalian Diaphanous-related (mDia1/2/3) formin GTPase effector proteins have been localized on endosomes, a role for their actin nucleation, filament elongation, and/or bundling remains poorly understood in the context of intracellular trafficking. In a study of a functional relationship between RhoB, a GTPase known to associate with both early- and late-endosomes, and the formin mDia2, we show that 1) RhoB and mDia2 interact on endosomes; 2) GTPase activity-the ability to hydrolyze GTP to GDP-is required for the ability of RhoB to govern endosome dynamics; and 3) the actin dynamics controlled by RhoB and mDia2 is necessary for vesicle trafficking. These studies further suggest that Rho GTPases significantly influence the activity of mDia family formins in driving cellular membrane remodeling through the regulation of actin dynamics.
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Affiliation(s)
- Bradley J Wallar
- Laboratory of Cell Structure and Signal Integration, Van Andel Research Institute, 333 Bostwick Avenue, Grand Rapids, MI 49503, USA
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13
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Matusek T, Djiane A, Jankovics F, Brunner D, Mlodzik M, Mihály J. The Drosophila formin DAAM regulates the tracheal cuticle pattern through organizing the actin cytoskeleton. Development 2006; 133:957-66. [PMID: 16469972 DOI: 10.1242/dev.02266] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Formins are involved in a wide range of cellular processes that require the remodeling of the actin cytoskeleton. Here, we have analyzed a novel Drosophila formin, belonging to the recently described DAAM subfamily. In contrast to previous assumptions, we show that DAAM plays no essential role in planar cell polarity signaling, but it has striking requirements in organizing apical actin cables that define the taenidial fold pattern of the tracheal cuticle. These observations provide evidence the first time that the function of the taenidial organization is to prevent the collapse of the tracheal tubes. Our results indicate that although DAAM is regulated by RhoA, it functions upstream or parallel to the non-receptor tyrosine kinases Src42A and Tec29 to organize the actin cytoskeleton and to determine the cuticle pattern of the Drosophila respiratory system.
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Affiliation(s)
- Tamás Matusek
- Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Temesvári krt. 62, Hungary
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14
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Badour K, Zhang J, Siminovitch KA. Involvement of the Wiskott-Aldrich syndrome protein and other actin regulatory adaptors in T cell activation. Semin Immunol 2005; 16:395-407. [PMID: 15541654 DOI: 10.1016/j.smim.2004.08.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The actin cytoskeleton is a dynamic structure recognized for many years as integral to the coupling of external stimuli to cell activation and ensuing changes in morphology and movement. It is only recently, however, that a molecular understanding of actin involvement in these activities has emerged coincident with the identification of cytosolic signaling effectors that couple extracellular stimuli to induction of actin nucleation. Notable among these actin regulatory effectors are members of the Wiskott-Aldrich syndrome protein (WASp) family, a group of cytoskeletal adaptors imbued with the capacity to connect various signal transduction pathways to the Arp 2/3 complex and Arp 2/3-mediated actin polymerization. In T cells, the functional characterization of WASp and other actin-modulatory adaptors has proved instrumental in delineating the molecular interactions evoking actin cytoskeletal reorganization downstream of antigen receptor engagement and in clarifying the influence of actin-based processes on T cell activation. In this review, the structural and functional properties of the major actin regulatory cytoskeletal adaptors in T cells are described with an emphasis on the roles of these proteins in fostering the TCR actin cytoskeletal interplay required for induction of T cell activation and expression of dynamic effector responses.
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Affiliation(s)
- Karen Badour
- Department of Medicine, McLaughlin Centre of Molecular Medicine, University of Toronto, Mount Sinai Hospital, Samuel Lunenfeld and Toronto General Hospital Research Institutes, 600 University Avenue, #656A, Toronto, Ont., Canada M5G 1X5.
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15
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Abstract
Evolutionarily conserved in eukaryotes, formin homology (FH) proteins, or formins, exert their effects on the actin and microtubule (MT) networks during meiosis, mitosis, the maintenance of cell polarity, vesicular trafficking, signaling to the nucleus and embryonic development. Once thought to be only molecular scaffolds that indirectly affected cellular functions through the binding of other proteins, recent in vitro studies have illustrated that they can function as actin nucleators in the formation of new filaments. The connection between formins and MTs is less well understood. In yeast, the MT effects appear to be dependent on the ability of formins to generate polarized actin cables whereas, in mammalian cells, formin signals that cause MT stabilization and polarization might be more direct. A subclass of formins, the Diaphanous-related formins (Drfs), can act as effectors for Rho small GTPases, yet it is not clear what GTPase binding contributes to formin function.
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Affiliation(s)
- Bradley J Wallar
- Laboratory of Cell Structure and Signal Integration, Van Andel Research Institute, 333 Bostwick Avenue N.E., Grand Rapids, MI 49503, USA
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16
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Haendeler J, Hoffmann J, Brandes RP, Zeiher AM, Dimmeler S. Hydrogen peroxide triggers nuclear export of telomerase reverse transcriptase via Src kinase family-dependent phosphorylation of tyrosine 707. Mol Cell Biol 2003; 23:4598-610. [PMID: 12808100 PMCID: PMC164856 DOI: 10.1128/mcb.23.13.4598-4610.2003] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The regulation of telomerase reverse transcriptase (TERT) plays an important role in the proliferative capacity and survival of cells. Here, we report that exogenously as well as endogenously induced oxidative stress leads to translocation of endogenous as well as overexpressed human TERT from the nucleus into the cytosol. TERT is transported through the nuclear pores in a leptomycin-sensitive and Ran GTPase-dependent process. H(2)O(2)-induced nuclear export of TERT is preceded by TERT tyrosine phosphorylation at position 707 and prevented by the Src kinase family inhibitor PP1. Oxidative stress-induced nuclear export of TERT depends on association with the Ran GTPase. In contrast, mutation of tyrosine 707 inhibits phosphorylation induced by oxidative stress and prevents association with Ran and nuclear export of TERT. Moreover, inhibition of tyrosine phosphorylation at 707 increases the antiapoptotic capacity of TERT. Taken together, depletion of nuclear TERT by tyrosine phosphorylation-dependent nuclear export of TERT is a novel mechanism for regulation of TERT localization, which reduces the antiapoptotic activity of TERT.
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Affiliation(s)
- Judith Haendeler
- Molecular Cardiology, Department of Internal Medicine IV. Department of Physiology, University of Frankfurt, Frankfurt, Germany
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17
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Gasman S, Kalaidzidis Y, Zerial M. RhoD regulates endosome dynamics through Diaphanous-related Formin and Src tyrosine kinase. Nat Cell Biol 2003; 5:195-204. [PMID: 12577064 DOI: 10.1038/ncb935] [Citation(s) in RCA: 174] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2002] [Revised: 11/19/2002] [Accepted: 01/03/2003] [Indexed: 01/10/2023]
Abstract
Early endosomes move bidirectionally between the cell periphery and the interior through a mechanism regulated by the low molecular weight GTPase RhoD. Here, we identify a novel splice variant of human Diaphanous, hDia2C, which specifically binds to RhoD and is recruited onto early endosomes. Expression of RhoD and hDia2C induces a striking alignment of early endosomes along actin filaments and reduces their motility. This activity depends on the membrane recruitment and activation of c-Src kinase, thus uncovering a new role in endosome function. Our results define a novel signal transduction pathway, in which hDia2C and c-Src are sequentially activated by RhoD to regulate the motility of early endosomes through interactions with the actin cytoskeleton.
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Affiliation(s)
- Stéphane Gasman
- Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, Dresden D-01307, Germany
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18
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Copeland JW, Treisman R. The diaphanous-related formin mDia1 controls serum response factor activity through its effects on actin polymerization. Mol Biol Cell 2002; 13:4088-99. [PMID: 12429848 PMCID: PMC133616 DOI: 10.1091/mbc.02-06-0092] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
SRF-dependent transcription is regulated by the small GTPase RhoA via its effects on actin dynamics. The diaphanous-related formin (DRF) proteins have been identified as candidate RhoA effectors mediating signaling to SRF. Here we investigate the relationship between SRF activation and actin polymerization by the DRF mDia1. We show that the ability of mDia1 to potentiate SRF activity is strictly correlated with its ability to promote F-actin assembly. Both processes can occur independently of the mDia1 FH1 domain but require sequences in an extended C-terminal region encompassing the conserved FH2 domain. mDia-mediated SRF activation, but not F-actin assembly, can be blocked by a nonpolymerizable actin mutant, placing actin downstream of mDia in the signal pathway. The SRF activation assay was used to identify inactive mDia1 derivatives that inhibit serum- and LPA-induced signaling to SRF. We show that these interfering mutants also block F-actin assembly, whether induced by mDia proteins or extracellular signals. These results identify novel functional elements of mDia1 and show that it regulates SRF activity by inducing depletion of the cellular pool of G-actin.
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Affiliation(s)
- John W Copeland
- Cancer Research UK, London Research Institute, Lincoln's Inn Fields laboratories
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19
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Sharpless KE, Harris SD. Functional characterization and localization of the Aspergillus nidulans formin SEPA. Mol Biol Cell 2002; 13:469-79. [PMID: 11854405 PMCID: PMC65642 DOI: 10.1091/mbc.01-07-0356] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Formins are a family of multidomain scaffold proteins involved in actin-dependent morphogenetic events. In Aspergillus nidulans, the formin SEPA participates in two actin-mediated processes, septum formation and polarized growth. In this study, we use a new null mutant to demonstrate that SEPA is required for the formation of actin rings at septation sites. In addition, we find that a functional SEPA::GFP fusion protein localizes simultaneously to septation sites and hyphal tips, and that SEPA colocalizes with actin at each site. Using live imaging, we show that SEPA localization at septation sites and hyphal tips is dynamic. Notably, at septation sites, SEPA forms a ring that constricts as the septum is deposited. Moreover, we demonstrate that actin filaments are required to maintain the proper localization pattern of SEPA, and that the amino-terminal half of SEPA is sufficient for localization at septation sites and hyphal tips. In contrast, only localization at septation sites is affected by loss of the sepH gene product. We propose that specific morphological cues activate common molecular pathways to direct SEPA localization to the appropriate morphogenetic site.
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Affiliation(s)
- Kathryn E Sharpless
- Department of Microbiology, University of Connecticut Health Center, Farmington, Connecticut 06030-3205, USA
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20
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Westendorf JJ. The formin/diaphanous-related protein, FHOS, interacts with Rac1 and activates transcription from the serum response element. J Biol Chem 2001; 276:46453-9. [PMID: 11590143 DOI: 10.1074/jbc.m105162200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
FHOS is a member of the formin homology (FH) family of proteins and is expressed at high levels in splenic cells. FH proteins link cellular signaling pathways to the actin cytoskeleton and serum response factor-dependent transcription. In these studies, the role of FHOS in Rho family GTPase signaling pathways was analyzed. FHOS interacted with the polybasic domain in the Rac1 C terminus in a guanine nucleotide-independent manner but did not interact with RhoA, Cdc42Hs, Rac2, or Rac3. Intramolecular autoinhibitory interactions between the C terminus of FHOS and an N-terminal region partially overlapping the Rac1 interaction domain were also identified. FHOS truncation mutants lacking the N- or C-terminal autoregulatory domains stimulated transcription of a c-fos serum response element (SRE)-driven reporter. Overexpression of wild-type and mutant (N17 and V12) Rac1 proteins repressed SRE induction by the N-terminal FHOS deletion mutant but not by the C-terminal FHOS deletion mutant. Immunofluorescence studies indicated that the localization of the mutant FHOS proteins might contribute to their differential responses to Rac1. Wild-type FHOS and the N-terminal deletion mutant localized to the perinuclear region and membrane edges. In contrast, the C-terminal FHOS mutants were diffusely localized. These data suggest that FHOS induces transcription from SREs by multiple pathways and that Rac1 may influence the course of some FHOS-induced signaling events.
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Affiliation(s)
- J J Westendorf
- Department of Orthopaedic Surgery and University of Minnesota Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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21
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Alberts AS. Identification of a carboxyl-terminal diaphanous-related formin homology protein autoregulatory domain. J Biol Chem 2001; 276:2824-30. [PMID: 11035012 DOI: 10.1074/jbc.m006205200] [Citation(s) in RCA: 272] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian and fungal Diaphanous-related formin homology (DRF) proteins contain several regions of conserved sequence homology. These include an amino-terminal GTPase binding domain (GBD) that interacts with activated Rho family members and formin homology domains that mediate targeting or interactions with signaling kinases and actin-binding proteins. DRFs also contain a conserved Dia-autoregulatory domain (DAD) in their carboxyl termini that binds the GBD. The GBD is a bifunctional autoinhibitory domain that is regulated by activated Rho. Expression of the isolated DAD in cells causes actin fiber formation and stimulates serum response factor-regulated gene expression. Inhibitor experiments show that the effects of exogenous DAD expression are dependent upon cellular Dia proteins. Alanine substitution of DAD consensus residues that disrupt GBD binding also eliminate DAD biological activity. Thus, DAD expression activates nuclear signaling and actin remodeling by mimicking activated Rho and unlatching the autoinhibited state of the cellular complement of Dia proteins.
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Affiliation(s)
- A S Alberts
- Laboratory of Cell Structure and Signal Integration, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA.
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22
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O'Rourke DA, Liu ZX, Sellin L, Spokes K, Zeller R, Cantley LG. Hepatocyte growth factor induces MAPK-dependent formin IV translocation in renal epithelial cells. J Am Soc Nephrol 2000; 11:2212-2221. [PMID: 11095644 DOI: 10.1681/asn.v11122212] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Renal epithelial tubule formation in cultured cells occurs after the addition of tubulogenic growth factors such as the hepatocyte growth factor (HGF). HGF activates the tyrosine kinase receptor c-met, initiating a series of complex events that regulate cell morphology, cell-cell interactions, and cell-matrix interactions and eventually result in the formation of branching tubular structures. The discovery that disruption of the formin gene locus in mice causes agenesis of the kidneys secondary to failure of ureteric bud outgrowth and branching tubule formation suggested that this family of proteins may be critical to the development of renal epithelial tubules. In this study, we investigated whether formin is involved in the HGF/c-met signaling pathway of in vitro tubulogenesis in renal epithelial cells. mIMCD-3 cells were analyzed by reverse transcription-PCR and found to express formin IV mRNA. With the use of an antibody that recognizes the carboxy terminus of all known formin isoforms, it was observed a formin isoform of approximately 165 kD markedly increased in the detergent soluble cell lysate after 10 min of stimulation with HGF. An antibody that is specific for formin IV was then generated and confirmed that the formin isoform regulated by HGF was formin IV. Cell fractionation and confocal localization of formin IV revealed that formin IV is primarily found in a submembranous band that co-localizes with the actin cytoskeleton and in a perinuclear location in quiescent epithelial cells but undergoes a rapid relocalization after HGF stimulation with translocation into the cell cytosol and into the nucleus. Formin IV was found to be a phosphorylation substrate for activated extracellular signal-regulated kinase in vitro, and pretreatment of cells with the mitogen-activated protein kinase inhibitor U0126 prevented the translocation of formin IV and inhibited HGF-dependent phosphorylation of formin IV in intact cells. In conclusion, activation of the c-met receptor results in cellular relocalization of formin IV in a mitogen-activated protein kinase-dependent manner.
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Affiliation(s)
| | - Zhen-Xiang Liu
- Section of Nephrology, Yale University, School of Medicine, New Haven, Connecticut
| | - Lorenz Sellin
- Section of Nephrology, University of Freiburg, Freiburg, Germany
| | - Katherine Spokes
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Rolf Zeller
- University of Utrecht, Utrecht, The Netherlands
| | - Lloyd G Cantley
- Section of Nephrology, Yale University, School of Medicine, New Haven, Connecticut
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23
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Leader B, Leder P. Formin-2, a novel formin homology protein of the cappuccino subfamily, is highly expressed in the developing and adult central nervous system. Mech Dev 2000; 93:221-31. [PMID: 10781961 DOI: 10.1016/s0925-4773(00)00276-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Formin-1 is the founding member of a family of genes of emerging biological and medical importance that share specific domains of homology, allowing them to be classified together as the formin homology proteins. Although deficiency mutations in formin-1 lead to profound developmental defects in limb and kidney formation, similar deficiency mutations in more distantly related members of this family (diaphanous and cappuccino in Drosophila and BNI1 in yeast) have ostensibly unrelated phenotypes. Here we describe murine and human formin-2 (Fmn2), a gene which bears a high degree of similarity to formin-1 and cappuccino. The mouse gene, which encodes a putative 1567-amino-acid open reading frame and maps to mouse Chromosome 1, is expressed almost exclusively in the developing and mature central nervous system. Expression begins at embryonic day 9. 5 in the developing spinal cord and brain structures and continues in neonatal and adult brain structures including the olfactory bulb, cortex, thalamus, hypothalamus, hippocampus and cerebellum. Human formin-2 has a similar expression pattern.
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Affiliation(s)
- B Leader
- Department of Genetics, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115, USA.
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24
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Tominaga T, Sahai E, Chardin P, McCormick F, Courtneidge SA, Alberts AS. Diaphanous-related formins bridge Rho GTPase and Src tyrosine kinase signaling. Mol Cell 2000; 5:13-25. [PMID: 10678165 DOI: 10.1016/s1097-2765(00)80399-8] [Citation(s) in RCA: 323] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We have examined the role of the mouse Diaphanous-related formin (DRF) Rho GTPase binding proteins, mDia1 and mDia2, in cell regulation. The DRFs are required for cytokinesis, stress fiber formation, and transcriptional activation of the serum response factor (SRF). 'Activated' mDia1 and mDia2 variants, lacking their GTPase binding domains, cooperated with Rho-kinase or ROCK to form stress fibers but independently activated SRF. Src tyrosine kinase associated and co-localized with the DRFs in endosomes and in mid-bodies of dividing cells. Inhibition of Src also blocked cytokinesis, SRF induction by activated DRFs, and cooperative stress fiber formation with active ROCK. Our results show that the DRF proteins couple Rho and Src during signaling and the regulation of actin dynamics.
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Affiliation(s)
- T Tominaga
- University of California, San Francisco Cancer Center 94115, USA
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25
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Horster MF, Braun GS, Huber SM. Embryonic renal epithelia: induction, nephrogenesis, and cell differentiation. Physiol Rev 1999; 79:1157-91. [PMID: 10508232 DOI: 10.1152/physrev.1999.79.4.1157] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Embryonic metanephroi, differentiating into the adult kidney, have come to be a generally accepted model system for organogenesis. Nephrogenesis implies a highly controlled series of morphogenetic and differentiation events that starts with reciprocal inductive interactions between two different primordial tissues and leads, in one of two mainstream processes, to the formation of mesenchymal condensations and aggregates. These go through the intricate process of mesenchyme-to-epithelium transition by which epithelial cell polarization is initiated, and they continue to differentiate into the highly specialized epithelial cell populations of the nephron. Each step along the developmental metanephrogenic pathway is initiated and organized by signaling molecules that are locally secreted polypeptides encoded by different gene families and regulated by transcription factors. Nephrogenesis proceeds from the deep to the outer cortex, and it is directed by a second, entirely different developmental process, the ductal branching of the ureteric bud-derived collecting tubule. Both systems, the nephrogenic (mesenchymal) and the ductogenic (ureteric), undergo a repeat series of inductive signaling that serves to organize the architecture and differentiated cell functions in a cascade of developmental gene programs. The aim of this review is to present a coherent picture of principles and mechanisms in embryonic renal epithelia.
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Affiliation(s)
- M F Horster
- Physiologisches Institut, Universität München, München, Germany.
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26
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Westendorf JJ, Mernaugh R, Hiebert SW. Identification and characterization of a protein containing formin homology (FH1/FH2) domains. Gene 1999; 232:173-82. [PMID: 10352228 DOI: 10.1016/s0378-1119(99)00127-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A novel member of the Formin/Diaphanous family of proteins was cloned and characterized. A 4kB mRNA is ubiquitously expressed but is found in abundance in the spleen. FHOS (Formin Homologue Overexpressed in Spleen) contains a 3414bp open reading frame and encodes for an approximately 128kDa protein. FHOS has sequence homology to Diaphanous and Formin proteins within the Formin Homology (FH)1 and FH2 domains. FHOS also contains a coiled-coil, a collagen-like domain, two nuclear localization signals, and several potential PKC and PKA phosphorylation sites. FHOS-specific antiserum was generated and used to determine that FHOS is a predominantly cytoplasmic protein and is expressed in a variety of human cell lines. FHOS was mapped to chromosome 16q22 between framework markers WI-5594 and WI-9392.
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Affiliation(s)
- J J Westendorf
- Vanderbilt University, Department of Biochemistry and Vanderbilt Cancer Center, Nashville, TN 37232, USA
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27
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Abstract
The development of the mature mammalian kidney begins with the invasion of metanephric mesenchyme by ureteric bud. Mesenchymal cells near the bud become induced and convert to an epithelium which goes on to generate the functional filtering unit of the kidney, the nephron. The collecting duct system is elaborated by the branching ureter, the growth of which is dependent upon signals from the metanephric mesenchyme. The process of reciprocal induction between ureter and mesenchyme is repeated many times over during development and is the key step in generating the overall architecture of the kidney. Genetic studies in mice have allowed researchers to begin to unravel the molecular signals that govern these early events. These experiments have revealed that a number of essential gene products are required for distinct steps in kidney organogenesis. Here we review and summarize the developmental role played by some of these molecules, especially certain transcription factors and growth factors and their receptors. Although the factors involved are far from completely known a rough framework of a molecular cascade which governs embryonic kidney development is beginning to emerge.
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Affiliation(s)
- M S Lechner
- Howard Hughes Medical Institute and Department of Pathology, University of Michigan, Ann Arbor 48109-0650, USA
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28
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Worley TL, Cornel E, Holt CE. Overexpression of c-src and n-src in the developing Xenopus retina differentially impairs axonogenesis. Mol Cell Neurosci 1997; 9:276-92. [PMID: 9268506 DOI: 10.1006/mcne.1997.0620] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
To compare the roles of the nonreceptor tyrosine kinase c-src and its neuronal splice form n-src in developing neurons, Xenopus retinal precursors were transfected in vivo with c-src, n-src, or constitutively active mutants. Axonogenesis of retinal ganglion cells was markedly impaired by the expression of constitutively active c-src and only mildly affected by the expression of constitutively active n-src. This differential phenotype could not be accounted for by raised levels of intracellular tyrosine phosphorylation alone because the average anti-phosphotyrosine staining intensity of retinal neurons expressing mutant n-src was almost twofold greater than that of neurons expressing mutant c-src. The expression of either constitutively active isoform inhibited photoreceptor differentiation by 72% but did not influence other cell fates. These results suggest that c-src and n-src have both overlapping and distinct activities in differentiating retinal neurons.
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Affiliation(s)
- T L Worley
- Department of Biology 0366, University of California, San Diego, La Jolla 92093, USA
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