1
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Son H, Jung YJ, Park SC, Kim IR, Park JH, Jang MK, Lee JR. Functional Characterization of an Arabidopsis Profilin Protein as a Molecular Chaperone under Heat Shock Stress. Molecules 2022; 27:molecules27185771. [PMID: 36144503 PMCID: PMC9504416 DOI: 10.3390/molecules27185771] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/29/2022] [Accepted: 09/02/2022] [Indexed: 11/16/2022] Open
Abstract
Profilins (PFNs) are actin monomer-binding proteins that function as antimicrobial agents in plant phloem sap. Although the roles of Arabidopsis thaliana profilin protein isoforms (AtPFNs) in regulating actin polymerization have already been described, their biochemical and molecular functions remain to be elucidated. Interestingly, a previous study indicated that AtPFN2 with high molecular weight (HMW) complexes showed lower antifungal activity than AtPFN1 with low molecular weight (LMW). These were bacterially expressed and purified to characterize the unknown functions of AtPFNs with different structures. In this study, we found that AtPFN1 and AtPFN2 proteins have LMW and HMW structures, respectively, but only AtPFN2 has a potential function as a molecular chaperone, which has never been reported elsewhere. AtPFN2 has better protein stability than AtPFN1 due to its higher molecular weight under heat shock conditions. The function of AtPFN2 as a holdase chaperone predominated in the HMW complexes, whereas the chaperone function of AtPFN1 was not observed in the LMW forms. These results suggest that AtPFN2 plays a critical role in plant tolerance by increasing hydrophobicity due to external heat stress.
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Affiliation(s)
- Hyosuk Son
- Department of Polymer Science and Engineering, Sunchon National University, Suncheon 38286, Korea
- National Marine Biodiversity Institute of Korea, Seocheon 33662, Korea
| | - Young Jun Jung
- National Institute of Ecology (NIE), Seocheon 33657, Korea
| | - Seong-Cheol Park
- Department of Polymer Science and Engineering, Sunchon National University, Suncheon 38286, Korea
| | - Il Ryong Kim
- National Institute of Ecology (NIE), Seocheon 33657, Korea
| | - Joung Hun Park
- Division of Applied Life Science (BK21+) and PMBBRC, Gyeongsang National University, Jinju 52828, Korea
| | - Mi-Kyeong Jang
- Department of Polymer Science and Engineering, Sunchon National University, Suncheon 38286, Korea
- Correspondence: (M.-K.J.); (J.R.L.); Tel.: +82-62-750-3567 (M.-K.J.); +82-41-950-5820 (J.R.L.)
| | - Jung Ro Lee
- National Institute of Ecology (NIE), Seocheon 33657, Korea
- Correspondence: (M.-K.J.); (J.R.L.); Tel.: +82-62-750-3567 (M.-K.J.); +82-41-950-5820 (J.R.L.)
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2
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Identification and characterization of profilin gene family in rice. ELECTRON J BIOTECHN 2021. [DOI: 10.1016/j.ejbt.2021.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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3
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Bharadwaj R, Bhattacharya A, Somlata. Coordinated activity of amoebic formin and profilin are essential for phagocytosis. Mol Microbiol 2021; 116:974-995. [PMID: 34278607 DOI: 10.1111/mmi.14787] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 10/24/2022]
Abstract
For the protist parasite Entamoeba histolytica, endocytic processes, such as phagocytosis, are essential for its survival in the human gut. The actin cytoskeleton is involved in the formation of pseudopods and phagosomal vesicles by incorporating a number of actin-binding and modulating proteins along with actin in a temporal manner. The actin dynamics, which comprises polymerization, branching, and depolymerization is very tightly regulated and takes place directionally at the sites of initiation of phagocytosis. Formin and profilin are two actin-binding proteins that are known to regulate actin cytoskeleton dynamics and thereby, endocytic processes. In this article, we report the participation of formin and profilin in E. histolytica phagocytosis and propose that these two proteins interact with each other and their sequential recruitment at the site is required for the successful completion of phagocytosis. The evidence is based on detailed microscopic, live imaging, interaction studies, and expression downregulation. The cells downregulated for expression of formin show absence of profilin at the site of phagocytosis, whereas downregulation of profilin does not affect formin localization.
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Affiliation(s)
- Ravi Bharadwaj
- Department of Medicine, UMass Medical School, Worcester, MA, USA
| | | | - Somlata
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, New Delhi, India
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4
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Abstract
Dynamic remodeling of the actin cytoskeleton is an essential feature for virtually all actin-dependent cellular processes, including cell migration, cell cycle progression, chromatin remodeling and gene expression, and even the DNA damage response. An altered actin cytoskeleton is a structural hallmark associated with numerous pathologies ranging from cardiovascular diseases to immune disorders, neurological diseases and cancer. The actin cytoskeleton in cells is regulated through the orchestrated actions of a myriad of actin-binding proteins. In this Review, we provide a brief overview of the structure and functions of the actin-monomer-binding protein profilin-1 (Pfn1) and then discuss how dysregulated expression of Pfn1 contributes to diseases associated with the cardiovascular system.
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Affiliation(s)
| | - David Gau
- Bioengineering, University of Pittsburgh
| | - Partha Roy
- Bioengineering, University of Pittsburgh.,Pathology, University of Pittsburgh, 306 Center for Bioengineering, University of Pittsburgh, 300 Technology Drive, Pittsburgh, PA 15219, USA
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5
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Das P, Pal S, Oldfield CM, Thillai K, Bala S, Carnevale KA, Cathcart MK, Bhattacharjee A. A PKCβ-LYN-PYK2 Signaling Axis Is Critical for MCP-1-Dependent Migration and Adhesion of Monocytes. THE JOURNAL OF IMMUNOLOGY 2021; 206:181-192. [PMID: 33277387 DOI: 10.4049/jimmunol.1900706] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 11/02/2020] [Indexed: 11/19/2022]
Abstract
MCP-1-induced monocyte chemotaxis is a crucial event in inflammation and atherogenesis. Identifying the important signal transduction pathways that control monocyte chemotaxis can unravel potential targets for preventive therapies in inflammatory disease conditions. Previous studies have shown that the focal adhesion kinase Pyk2 plays a critical role in monocyte motility. In this study, we investigated the MCP-1-mediated activation of Pyk2 (particularly by the phosphorylation of Tyr402) in primary human peripheral blood monocytes. We showed that MCP-1 induces Src phosphorylation in a similar time frame and that the MCP-1-induced Pyk2 tyrosine phosphorylation is controlled by the Src family kinase. We also report, in this study, that PKCβ, an isoform of PKC, is required for both Src and Pyk2 activation/phosphorylation in response to MCP-1 stimulation. We identified Lyn as the specific Src kinase isoform that is activated by MCP-1 and acts upstream of Pyk2 in primary monocytes. Furthermore, Lyn is found to be indispensable for monocyte migration in response to MCP-1 stimulation. Moreover, our coimmunoprecipitation studies in monocytes revealed that PKCβ, Pyk2, and Lyn exist constitutively in a molecular complex. To our knowledge, our study has uncovered a novel PKCβ-Lyn-Pyk2 signaling cascade in primary monocytes that regulates MCP-1-induced monocyte adhesion and migration.
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Affiliation(s)
- Pradip Das
- Department of Biotechnology, National Institute of Technology-Durgapur, Durgapur 713209, Burdwan, West Bengal, India
| | - Srabani Pal
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195; and.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195
| | - Claudine M Oldfield
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195; and.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195
| | - Kowsalya Thillai
- Department of Biotechnology, National Institute of Technology-Durgapur, Durgapur 713209, Burdwan, West Bengal, India
| | - Sinjini Bala
- Department of Biotechnology, National Institute of Technology-Durgapur, Durgapur 713209, Burdwan, West Bengal, India
| | - Kevin A Carnevale
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195; and.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195
| | - Martha K Cathcart
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195; and.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195
| | - Ashish Bhattacharjee
- Department of Biotechnology, National Institute of Technology-Durgapur, Durgapur 713209, Burdwan, West Bengal, India;
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6
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Gau D, Vignaud L, Allen A, Guo Z, Sahel J, Boone D, Koes D, Guillonneau X, Roy P. Disruption of profilin1 function suppresses developmental and pathological retinal neovascularization. J Biol Chem 2020; 295:9618-9629. [PMID: 32444495 PMCID: PMC7363146 DOI: 10.1074/jbc.ra120.012613] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 05/20/2020] [Indexed: 12/18/2022] Open
Abstract
Angiogenesis-mediated neovascularization in the eye is usually associated with visual complications. Pathological angiogenesis is particularly prominent in the retina in the settings of proliferative diabetic retinopathy, in which it can lead to permanent loss of vision. In this study, by bioinformatics analyses, we provide evidence for elevated expression of actin-binding protein PFN1 (profilin1) in the retinal vascular endothelial cells (VECs) of individuals with proliferative diabetic retinopathy, findings further supported by gene expression analyses for PFN1 in experimentally induced abnormal retinal neovascularization in an oxygen-induced retinopathy murine model. We observed that in a conditional knockout mouse model, postnatal deletion of the Pfn1 gene in VECs leads to defects in tip cell activity (marked by impaired filopodial protrusions) and reduced vascular sprouting, resulting in hypovascularization during developmental angiogenesis in the retina. Consistent with these findings, an investigative small molecule compound targeting the PFN1-actin interaction reduced random motility, proliferation, and cord morphogenesis of retinal VECs in vitro and experimentally induced abnormal retinal neovascularization in vivo In summary, these findings provide the first direct in vivo evidence that PFN1 is required for formation of actin-based protrusive structures and developmental angiogenesis in the retina. The proof of concept of susceptibility of abnormal angiogenesis to small molecule intervention of PFN1-actin interaction reported here lays a conceptual foundation for targeting PFN1 as a possible strategy in angiogenesis-dependent retinal diseases.
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Affiliation(s)
- David Gau
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Lucile Vignaud
- Institut de la Vision, Sorbonne Université, INSERM, Paris, France
| | - Abigail Allen
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Zhijian Guo
- Department of Nephrology, Southern Medical University, Guangzhou, China
| | - Jose Sahel
- Institut de la Vision, Sorbonne Université, INSERM, Paris, France,Department of Ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - David Boone
- Department of Biomedical Informatics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - David Koes
- Department of Computational Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | | - Partha Roy
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA .,Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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7
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Brown TL, Macklin WB. The Actin Cytoskeleton in Myelinating Cells. Neurochem Res 2020; 45:684-693. [PMID: 30847860 PMCID: PMC6732044 DOI: 10.1007/s11064-019-02753-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 02/11/2019] [Accepted: 02/12/2019] [Indexed: 12/15/2022]
Abstract
Myelinating cells of both the peripheral and central nervous systems (CNSs) undergo dramatic cytoskeletal reorganization in order to differentiate and produce myelin. Myelinating oligodendrocytes in the CNS show a periodic actin pattern, demonstrating tight regulation of actin. Furthermore, recent data demonstrate that actin polymerization drives early cell differentiation and that actin depolymerization drives myelin wrapping. Dysregulation of the actin cytoskeleton in myelinating cells is seen in some disease states. This review highlights the cytoskeletal molecules that regulate differentiation of and myelination by cells of the PNS and CNS, informing our understanding of neural development, in particular myelination.
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Affiliation(s)
- Tanya L Brown
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
- Cell Biology, Stem Cells, and Development Graduate Program, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Wendy B Macklin
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, 80045, USA.
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8
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Gagat M, Hałas-Wiśniewska M, Zielińska W, Izdebska M, Grzanka D, Grzanka A. The effect of piperlongumine on endothelial and lung adenocarcinoma cells with regulated expression of profilin-1. Onco Targets Ther 2018; 11:8275-8292. [PMID: 30538497 PMCID: PMC6255113 DOI: 10.2147/ott.s183191] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose The aim of the study was to evaluate the effect of piperlongumine (2 and 4 µM) on endothelial EA.hy926 and lung adenocarcinoma A549 cells with regulated expression of profilin-1 (PFN1). Material and methods The cytotoxicity of alkaloid was evaluated by MTT assay, while cell death was assessed using double staining with annexin V and propidium iodide. Subsequently, the level of PFN1 1) upregulation in EA.hy926 endothelial cells and 2) downregulation in A549 lung adenocarcinoma cells. The next step was the analysis of the effect of PFN1 manipulation on cytoskeletal proteins. Results The results showed that piperlongumine may inhibit proliferation of EA.hy926 and A549 cell lines and also induce cell death in a dose-dependent manner. Furthermore, endothelial cells with PFN1 overexpression showed lower sensitivity to alkaloid and strengthening of cell-cell interactions. In the case of A549 cells, loss of PFN1 expression resulted in a lower percentage of early apoptotic cells, reorganization of F-actin and vimentin network, and reduction of migratory potential. Conclusion We suggest that upregulation of PFN1 in endothelial cell line may stabilize the cell junctions. In turn, PFN1 downregulation in A549 cells probably suppresses cell migration and sensitizes cells to anticancer agents.
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Affiliation(s)
- Maciej Gagat
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
| | - Marta Hałas-Wiśniewska
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
| | - Wioletta Zielińska
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
| | - Magdalena Izdebska
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
| | - Dariusz Grzanka
- Department of Clinical Pathomorphology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland
| | - Alina Grzanka
- Department of Histology and Embryology, Faculty of Medicine, Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Bydgoszcz, Poland,
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9
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Gau D, Lewis T, McDermott L, Wipf P, Koes D, Roy P. Structure-based virtual screening identifies a small-molecule inhibitor of the profilin 1-actin interaction. J Biol Chem 2017; 293:2606-2616. [PMID: 29282288 DOI: 10.1074/jbc.m117.809137] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 12/08/2017] [Indexed: 01/01/2023] Open
Abstract
Profilin 1 (Pfn1) is an important regulator of the actin cytoskeleton and plays a vital role in many actin-based cellular processes. Therefore, identification of a small-molecule intervention strategy targeted against the Pfn1-actin interaction could have broad utility in cytoskeletal research and further our understanding of the role of Pfn1 in actin-mediated biological processes. Based on an already resolved Pfn1-actin complex crystal structure, we performed structure-based virtual screening of small-molecule libraries to seek inhibitors of the Pfn1-actin interaction. We identified compounds that match the pharmacophore of the key actin residues of Pfn1-actin interaction and therefore have the potential to act as competitive inhibitors of this interaction. Subsequent biochemical assays identified two candidate compounds with nearly identical structures that can mitigate the effect of Pfn1 on actin polymerization in vitro As a further proof-of-concept test for cellular effects of these compounds, we performed proximity ligation assays in endothelial cells (ECs) to demonstrate compound-induced inhibition of Pfn1-actin interaction. Consistent with the important role of Pfn1 in regulating actin polymerization and various fundamental actin-based cellular activities (migration and proliferation), treatment of these compounds reduced the overall level of cellular filamentous (F) actin, slowed EC migration and proliferation, and inhibited the angiogenic ability of ECs both in vitro and ex vivo In summary, this study provides the first proof of principle of small-molecule-mediated interference with the Pfn1-actin interaction. Our findings may have potential general utility for perturbing actin-mediated cellular activities and biological processes.
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Affiliation(s)
- David Gau
- From the Departments of Bioengineering
| | | | | | - Peter Wipf
- From the Departments of Bioengineering.,Chemistry
| | | | - Partha Roy
- From the Departments of Bioengineering, .,Cell Biology, and.,Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania 15219
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10
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Zhang Y, Yoshida A, Sakai N, Uekusa Y, Kumeta M, Yoshimura SH. In vivo dynamics of the cortical actin network revealed by fast-scanning atomic force microscopy. Microscopy (Oxf) 2017; 66:272-282. [DOI: 10.1093/jmicro/dfx015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/29/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Yanshu Zhang
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Aiko Yoshida
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | | | | | - Masahiro Kumeta
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shige H. Yoshimura
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
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11
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Hensel N, Claus P. The Actin Cytoskeleton in SMA and ALS: How Does It Contribute to Motoneuron Degeneration? Neuroscientist 2017; 24:54-72. [PMID: 28459188 DOI: 10.1177/1073858417705059] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA) are neurodegenerative diseases with overlapping clinical phenotypes based on impaired motoneuron function. However, the pathomechanisms of both diseases are largely unknown, and it is still unclear whether they converge on the molecular level. SMA is a monogenic disease caused by low levels of functional Survival of Motoneuron (SMN) protein, whereas ALS involves multiple genes as well as environmental factors. Recent evidence argues for involvement of actin regulation as a causative and dysregulated process in both diseases. ALS-causing mutations in the actin-binding protein profilin-1 as well as the ability of the SMN protein to directly bind to profilins argue in favor of a common molecular mechanism involving the actin cytoskeleton. Profilins are major regulat ors of actin-dynamics being involved in multiple neuronal motility and transport processes as well as modulation of synaptic functions that are impaired in models of both motoneuron diseases. In this article, we review the current literature in SMA and ALS research with a focus on the actin cytoskeleton. We propose a common molecular mechanism that explains the degeneration of motoneurons for SMA and some cases of ALS.
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Affiliation(s)
- Niko Hensel
- 1 Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,2 Niedersachsen Network on Neuroinfectiology (N-RENNT), Hannover, Germany
| | - Peter Claus
- 1 Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,2 Niedersachsen Network on Neuroinfectiology (N-RENNT), Hannover, Germany.,3 Center for Systems Neuroscience (ZSN), Hannover, Germany
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12
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Rennella E, Sekhar A, Kay LE. Self-Assembly of Human Profilin-1 Detected by Carr-Purcell-Meiboom-Gill Nuclear Magnetic Resonance (CPMG NMR) Spectroscopy. Biochemistry 2017; 56:692-703. [PMID: 28052669 DOI: 10.1021/acs.biochem.6b01263] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein oligomerization in the cell has important implications for both health and disease, and an understanding of the mechanisms by which proteins can self-associate is, therefore, of critical interest. Initial stages of the oligomerization process can be hard to detect, as they often involve the formation of sparsely populated and transient states that are difficult to characterize by standard biophysical approaches. Using relaxation dispersion nuclear magnetic resonance spectroscopy, we study the oligomerization of human profilin-1, a protein that regulates the polymerization of actin. We show that in solution and at millimolar concentrations profilin-1 is predominantly monomeric. However, fits of concentration-dependent relaxation data are consistent with the formation of a higher-order oligomer that is generated via a multistep process. Together with crystallographic data for profilin-2, a homologue of the protein studied here, our results suggest that profilin-1 forms a sparsely populated tetrameric conformer in solution.
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Affiliation(s)
- Enrico Rennella
- Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto , Toronto, Ontario M5S 1A8, Canada
| | - Ashok Sekhar
- Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto , Toronto, Ontario M5S 1A8, Canada
| | - Lewis E Kay
- Departments of Molecular Genetics, Biochemistry and Chemistry, The University of Toronto , Toronto, Ontario M5S 1A8, Canada.,Program in Molecular Structure and Function, Hospital for Sick Children , 555 University Avenue, Toronto, Ontario M5G 1X8, Canada
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13
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Jia H, Hu Y, Fan T, Li J. Hydrogen sulfide modulates actin-dependent auxin transport via regulating ABPs results in changing of root development in Arabidopsis. Sci Rep 2015; 5:8251. [PMID: 25652660 PMCID: PMC4317700 DOI: 10.1038/srep08251] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 01/12/2015] [Indexed: 01/22/2023] Open
Abstract
Hydrogen sulfide (H2S) signaling has been considered a key regulator of plant developmental processes and defenses. In this study, we demonstrate that high levels of H2S inhibit auxin transport and lead to alterations in root system development. H2S inhibits auxin transport by altering the polar subcellular distribution of PIN proteins. The vesicle trafficking and distribution of the PIN proteins are an actin-dependent process. H2S changes the expression of several actin-binding proteins (ABPs) and decreases the occupancy percentage of F-actin bundles in the Arabidopsis roots. We observed the effects of H2S on F-actin in T-DNA insertion mutants of cpa, cpb and prf3, indicating that the effects of H2S on F-actin are partially removed in the mutant plants. Thus, these data imply that the ABPs act as downstream effectors of the H2S signal and thereby regulate the assembly and depolymerization of F-actin in root cells. Taken together, our data suggest that the existence of a tightly regulated intertwined signaling network between auxin, H2S and actin that controls root system development. In the proposed process, H2S plays an important role in modulating auxin transport by an actin-dependent method, which results in alterations in root development in Arabidopsis.
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Affiliation(s)
- Honglei Jia
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yanfeng Hu
- Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Nangang District, Harbin 150000, China
| | - Tingting Fan
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Jisheng Li
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
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14
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Rotty JD, Wu C, Haynes EM, Suarez C, Winkelman JD, Johnson HE, Haugh JM, Kovar DR, Bear JE. Profilin-1 serves as a gatekeeper for actin assembly by Arp2/3-dependent and -independent pathways. Dev Cell 2014; 32:54-67. [PMID: 25543281 DOI: 10.1016/j.devcel.2014.10.026] [Citation(s) in RCA: 206] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 09/12/2014] [Accepted: 10/30/2014] [Indexed: 12/31/2022]
Abstract
Cells contain multiple F-actin assembly pathways, including the Arp2/3 complex, formins, and Ena/VASP, which have largely been analyzed separately. They collectively generate the bulk of F-actin from a common pool of G-actin; however, the interplay and/or competition between these pathways remains poorly understood. Using fibroblast lines derived from an Arpc2 conditional knockout mouse, we established matched-pair cells with and without the Arp2/3 complex. Arpc2(-/-) cells lack lamellipodia and migrate more slowly than WT cells but have F-actin levels indistinguishable from controls. Actin assembly in Arpc2(-/-) cells was resistant to cytochalasin-D and was highly dependent on profilin-1 and Ena/VASP but not formins. Profilin-1 depletion in WT cells increased F-actin and Arp2/3 complex in lamellipodia. Conversely, addition of exogenous profilin-1 inhibited Arp2/3 complex actin nucleation in vitro and in vivo. Antagonism of the Arp2/3 complex by profilin-1 in cells appears to maintain actin homeostasis by balancing Arp2/3 complex-dependent and -independent actin assembly pathways.
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Affiliation(s)
- Jeremy D Rotty
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Congying Wu
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Elizabeth M Haynes
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Cristian Suarez
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Jonathan D Winkelman
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Heath E Johnson
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - Jason M Haugh
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA; Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - James E Bear
- University of North Carolina Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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15
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Structural basis of thymosin-β4/profilin exchange leading to actin filament polymerization. Proc Natl Acad Sci U S A 2014; 111:E4596-605. [PMID: 25313062 PMCID: PMC4217450 DOI: 10.1073/pnas.1412271111] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Thymosin-β4 (Tβ4) and profilin are the two major sequestering proteins that maintain the pool of monomeric actin (G-actin) within cells of higher eukaryotes. Tβ4 prevents G-actin from joining a filament, whereas profilin:actin only supports barbed-end elongation. Here, we report two Tβ4:actin structures. The first structure shows that Tβ4 has two helices that bind at the barbed and pointed faces of G-actin, preventing the incorporation of the bound G-actin into a filament. The second structure displays a more open nucleotide binding cleft on G-actin, which is typical of profilin:actin structures, with a concomitant disruption of the Tβ4 C-terminal helix interaction. These structures, combined with biochemical assays and molecular dynamics simulations, show that the exchange of bound actin between Tβ4 and profilin involves both steric and allosteric components. The sensitivity of profilin to the conformational state of actin indicates a similar allosteric mechanism for the dissociation of profilin during filament elongation.
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16
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Montani L, Buerki-Thurnherr T, de Faria JP, Pereira JA, Dias NG, Fernandes R, Gonçalves AF, Braun A, Benninger Y, Böttcher RT, Costell M, Nave KA, Franklin RJM, Meijer D, Suter U, Relvas JB. Profilin 1 is required for peripheral nervous system myelination. Development 2014; 141:1553-61. [PMID: 24598164 DOI: 10.1242/dev.101840] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Myelination allows rapid saltatory propagation of action potentials along the axon and is an essential prerequisite for the normal functioning of the nervous system. During peripheral nervous system (PNS) development, myelin-forming Schwann cells (SCs) generate radial lamellipodia to sort and ensheath axons. This process requires controlled cytoskeletal remodeling, and we show that SC lamellipodia formation depends on the function of profilin 1 (Pfn1), an actin-binding protein involved in microfilament polymerization. Pfn1 is inhibited upon phosphorylation by ROCK, a downstream effector of the integrin linked kinase pathway. Thus, a dramatic reduction of radial lamellipodia formation is observed in SCs lacking integrin-linked kinase or treated with the Rho/ROCK activator lysophosphatidic acid. Knocking down Pfn1 expression by lentiviral-mediated shRNA delivery impairs SC lamellipodia formation in vitro, suggesting a direct role for this protein in PNS myelination. Indeed, SC-specific gene ablation of Pfn1 in mice led to profound radial sorting and myelination defects, confirming a central role for this protein in PNS development. Our data identify Pfn1 as a key effector of the integrin linked kinase/Rho/ROCK pathway. This pathway, acting in parallel with integrin β1/LCK/Rac1 and their effectors critically regulates SC lamellipodia formation, radial sorting and myelination during peripheral nervous system maturation.
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Affiliation(s)
- Laura Montani
- Instituto de Biologia Molecular e Celular, 4150-180 Porto, Portugal
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17
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Pečar Fonović U, Jevnikar Z, Rojnik M, Doljak B, Fonović M, Jamnik P, Kos J. Profilin 1 as a target for cathepsin X activity in tumor cells. PLoS One 2013; 8:e53918. [PMID: 23326535 PMCID: PMC3542269 DOI: 10.1371/journal.pone.0053918] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 12/04/2012] [Indexed: 12/14/2022] Open
Abstract
Cathepsin X has been reported to be a tumor promotion factor in various types of cancer; however, the molecular mechanisms linking its activity with malignant processes are not understood. Here we present profilin 1, a known tumor suppressor, as a target for cathepsin X carboxypeptidase activity in prostate cancer PC-3 cells. Profilin 1 co-localizes strongly with cathepsin X intracellularly in the perinuclear area as well as at the plasma membrane. Selective cleavage of C-terminal amino acids was demonstrated on a synthetic octapeptide representing the profilin C-terminal region, and on recombinant profilin 1. Further, intact profilin 1 binds its poly-L-proline ligand clathrin significantly better than it does the truncated one, as shown using cathepsin X specific inhibitor AMS-36 and immunoprecipitation of the profilin 1/clathrin complex. Moreover, the polymerization of actin, which depends also on the binding of poly-L-proline ligands to profilin 1, was promoted by AMS-36 treatment of cells and by siRNA cathepsin X silencing. Our results demonstrate that increased adhesion, migration and invasiveness of tumor cells depend on the inactivation of the tumor suppressive function of profilin 1 by cathepsin X. The latter is thus designated as a target for development of new antitumor strategies.
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Affiliation(s)
| | - Zala Jevnikar
- Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Matija Rojnik
- Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Bojan Doljak
- Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Marko Fonović
- Department of Biochemistry, Molecular and Structural Biology, Jozef Stefan Institute and Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, Ljubljana, Slovenia
| | | | - Janko Kos
- Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
- Department of Biotechnology, Jozef Stefan Institute, Ljubljana, Slovenia
- * E-mail:
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18
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Fan T, Zhai H, Shi W, Wang J, Jia H, Xiang Y, An L. Overexpression of profilin 3 affects cell elongation and F-actin organization in Arabidopsis thaliana. PLANT CELL REPORTS 2013; 32:149-60. [PMID: 23052593 DOI: 10.1007/s00299-012-1349-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/06/2012] [Accepted: 09/18/2012] [Indexed: 05/13/2023]
Abstract
KEY MESSAGE : Reduced levels of profilin 3 do not have a noticeable phenotypic effect; however, elevated profilin 3 levels result in decreased hypocotyl length due to a reduction in cell elongation and F-actin reorganization. The actin cytoskeleton is critical for a variety of cellular processes. The small actin monomer proteins, profilins (PRFs), are encoded by five highly conserved isoforms in Arabidopsis thaliana. PRF3, one of the vegetative isoforms, has 36 more N-terminal amino acid residues than the other four PRFs; however, the functions of PRF3 are mostly unknown. In this study, we demonstrated that PRF3 was strongly expressed in young seedlings, rosette leaves, and cauline leaves, but was weakly expressed in 14-day-old seedlings and flowers. Our data also showed that PRF3 could increase the critical concentration (Cc) of actin assembly in vitro. Overexpression of the full-length PRF3 cDNA resulted in a decrease in the lengths of roots and hypocotyls and delayed seed germination, but PRF3-ΔN36 transgenic plants and prf3 mutant plants showed normal growth when compared with wild-type plants. Microscopy observation revealed that cell elongation was inhibited in the hypocotyl and that F-actin was reorganized by destabilizing microfilaments. These results suggest that the dwarf phenotype of the PRF3 overexpression seedlings may be related to a reduction in cell length and F-actin rearrangement.
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Affiliation(s)
- Tingting Fan
- School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China.
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19
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Yao W, Yu X, Fang Z, Yin P, Zhao C, Li N, Wang L, Li Z, Zha X. Profilin1 facilitates staurosporine-triggered apoptosis by stabilizing the integrin β1-actin complex in breast cancer cells. J Cell Mol Med 2012; 16:824-35. [PMID: 21692986 PMCID: PMC3822851 DOI: 10.1111/j.1582-4934.2011.01369.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Profilin1 (Pfn1) functions as a tumour suppressor against malignant phenotypes of cancer cells. A minimum level of Pfn1 is critical for the differentiation of human epithelial cells, and its lower expression correlates with the tumourigenesis of breast cancer cells and tissues. However, the molecular mechanisms underlying its anti-tumour action remain largely unknown. In this study, we found that stable expression of ectopic Pfn1 sensitized the breast cancer cell line MDA-MB-468 to apoptosis induced by staurosporine, a widely used natural apoptosis-inducing agent. Pfn1 overexpression could also up-regulate the expression of integrin α5β1, which has been shown to inhibit the transformed phenotype of cancer cells. Furthermore, the Pfn1-facilitated apoptosis induced by staurosporine was blocked in cells attached to a supplementary fibronectin substrate, which serves as a ligand of integrin α5β1. These results suggest that the insufficient fibronectin caused by the integrin α5β1 up-regulation might activate a signalling pathway leading to an increase of cellular apoptosis. Moreover, Pfn1 that primarily functions to promote local superstructure formation involving actin filaments and integrin β1 may contribute to its promotion on apoptosis. Our study indicated a previously uncharacterized role of Pfn1 in mediating staurosporine-inducing apoptosis in breast cancer cells via up-regulating integrin α5β1, and suggested a new target for breast cancer therapy.
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Affiliation(s)
- Wantong Yao
- Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai, China
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20
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Ding Z, Bae YH, Roy P. Molecular insights on context-specific role of profilin-1 in cell migration. Cell Adh Migr 2012; 6:442-9. [PMID: 23076048 DOI: 10.4161/cam.21832] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Profilin-1 (Pfn1) is a ubiquitously expressed actin-monomer binding protein that has been linked to many cellular activities ranging from control of actin polymerization to gene transcription. Traditionally, Pfn1 has been considered to be an essential control element for actin polymerization and cell migration. Seemingly contrasting this view, a few recent studies have shown evidence of an inhibitory action of Pfn1 on motility of certain types of carcinoma cells. In this review, we summarize biochemistry and functional aspects of Pfn1 in normal cells and bring in newly emerged action of Pfn1 in cancer cells that may explain its context-specific role in cell migration.
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Affiliation(s)
- Zhijie Ding
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
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21
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Zhu HY, Riau A, Beuerman R. Epithelial microfilament regulators show regional distribution in mouse conjunctiva. Mol Vis 2010; 16:2215-24. [PMID: 21151337 PMCID: PMC2994345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Accepted: 10/19/2010] [Indexed: 11/10/2022] Open
Abstract
PURPOSE The conjunctival epithelium is a continuous sheet of cells with regional characteristics that appear to be similar. This study was designed to investigate the distribution and levels of expression of a subset of microfilament regulators in the forniceal, palpebral, and bulbar conjunctival epithelia. METHODS Balb/C mice were used. The localizations of paxillin, focal adhesion kinase, vinculin, talin1, cofilin, profilin, gelsolin, integrin β1, and integrin α6 were studied with the use of cross-sectional immunofluorescent staining. For a detailed cellular analysis, positioning and ablation with the laser microbeam (PALM) Combi System was used to obtain forniceal, bulbar, and palpebral conjunctival epithelia for expression comparison with the use of western blot analysis and quantitative real-time polymerase chain reaction. RESULTS Immunostaining showed that focal adhesion kinase, cofilin, profilin, gelsolin, talin1, and vinculin were expressed in all layers of the forniceal, palpebral, and bulbar conjunctival epithelia. Paxillin, integrin β1, and α6 was found to be located in the basal cell layer in all three of these areas. Quantitative real-time polymerase chain reaction showed that the transcript levels of these microfilament regulators in the forniceal conjunctivae were higher than those levels found in the bulbar and palpebral conjunctivae. Western blot analysis confirmed the differential expression levels of these microfilament regulators in the forniceal, bulbar, and palpebral conjunctivae. CONCLUSIONS Differences in the levels of microfilament regulators in the forniceal, bulbar, and palpebral conjunctivae suggest different modes of interaction with their microenvironment and within cell layers.
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Affiliation(s)
- Hong-Yuan Zhu
- Singapore Eye Research Institute, Yong Loo Lin School of Medicine, National University of Singapore, Singapore,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - A.K. Riau
- Singapore Eye Research Institute, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - R.W. Beuerman
- Singapore Eye Research Institute, Yong Loo Lin School of Medicine, National University of Singapore, Singapore,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore,Duke-NUS SRP Neuroscience and Behavioral Disorders, Singapore
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22
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Fine-tuning of neuronal architecture requires two profilin isoforms. Proc Natl Acad Sci U S A 2010; 107:15780-5. [PMID: 20798032 DOI: 10.1073/pnas.1004406107] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two profilin isoforms (PFN1 and PFN2a) are expressed in the mammalian brain. Although profilins are essential for regulating actin dynamics in general, the specific role of these isoforms in neurons has remained elusive. We show that knockdown of the neuron-specific PFN2a results in a significant reduction in dendrite complexity and spine numbers of hippocampal neurons. Overexpression of PFN1 in PFN2a-deficient neurons prevents the loss of spines but does not restore dendritic complexity. Furthermore, we show that profilins are involved in differentially regulating actin dynamics downstream of the pan-neurotrophin receptor (p75(NTR)), a receptor engaged in modulating neuronal morphology. Overexpression of PFN2a restores the morphological changes in dendrites caused by p75(NTR) overexpression, whereas PFN1 restores the normal spine density. Our data assign specific functions to the two PFN isoforms, possibly attributable to different affinities for potent effectors also involved in actin dynamics, and suggest that they are important for the signal-dependent fine-tuning of neuronal architecture.
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23
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Pontrello CG, Ethell IM. Accelerators, Brakes, and Gears of Actin Dynamics in Dendritic Spines. ACTA ACUST UNITED AC 2009; 3:67-86. [PMID: 20463852 DOI: 10.2174/1874082000903020067] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dendritic spines are actin-rich structures that accommodate the postsynaptic sites of most excitatory synapses in the brain. Although dendritic spines form and mature as synaptic connections develop, they remain plastic even in the adult brain, where they can rapidly grow, change, or collapse in response to normal physiological changes in synaptic activity that underlie learning and memory. Pathological stimuli can adversely affect dendritic spine shape and number, and this is seen in neurodegenerative disorders and some forms of mental retardation and autism as well. Many of the molecular signals that control these changes in dendritic spines act through the regulation of filamentous actin (F-actin), some through direct interaction with actin, and others via downstream effectors. For example, cortactin, cofilin, and gelsolin are actin-binding proteins that directly regulate actin dynamics in dendritic spines. Activities of these proteins are precisely regulated by intracellular signaling events that control their phosphorylation state and localization. In this review, we discuss how actin-regulating proteins maintain the balance between F-actin assembly and disassembly that is needed to stabilize mature dendritic spines, and how changes in their activities may lead to rapid remodeling of dendritic spines.
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Affiliation(s)
- Crystal G Pontrello
- Biomedical Sciences Division and Neuroscience program, University of California Riverside, USA
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24
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Abstract
Thirty years after its initial characterization and more than 1000 publications listed in PubMed describing its properties, the small (ca 15 kDa) protein profilin continues to surprise us with new, recently discovered functions. Originally described as an actin-binding protein, profilin has now been shown to interact with more than a dozen proteins in mammalian cells. Some of the more recently described and intriguing interactions are within neurons involving a neuronal profilin family member. Profilin is now regarded as a regulator of various cellular processes such as cytoskeletal dynamics, membrane trafficking and nuclear transport. Profilin is a necessary element in key steps of neuronal differentiation and synaptic plasticity, and embodies properties postulated for a synaptic tag. These findings identify profilin as an important factor linking cellular and behavioural plasticity in neural circuits.
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Affiliation(s)
- Andreas Birbach
- Medical University of Vienna, Währingerstrasse 13a, A-1090 Vienna, Austria.
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25
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Nie Z, Xu J, Chen J, Lv Z, Wang D, Sheng Q, Wu Y, Wang X, Wu X, Zhang Y. Expression analysis and characteristics of profilin gene from silkworm, Bombyx mori. Appl Biochem Biotechnol 2008; 158:59-71. [PMID: 18633732 DOI: 10.1007/s12010-008-8302-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2008] [Accepted: 06/17/2008] [Indexed: 11/24/2022]
Abstract
A recombinant Bombyx mori profilin protein (rBmPFN) was overexpressed in Escherichia coli BL21. Purified rBmPFN was used to generate anti-BmPFN polyclonal antibody, which were used to determine the subcellular localization of BmPFN. Immunostaining indicated that profilin can be found in both the nucleus and cytoplasm but is primarily located in the cytoplasm. Real-time RT-PCR and Western blot analyses indicated that, during the larvae stage, profilin expression levels are highest in the silk gland, followed by the gonad, and are lowest in the fatty body. Additionally, BmPFN expression begins during the egg stage, increases during the larvae stage, reaches a peak during the pupa stage, and decreases significantly in the moth. Therefore, we propose that BmPFN may play an important role during larva stage development, especially in the silk gland.
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Affiliation(s)
- Zuoming Nie
- Institute of Biochemistry, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, China
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26
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Mishra RS, Carnevale KA, Cathcart MK. iPLA2beta: front and center in human monocyte chemotaxis to MCP-1. ACTA ACUST UNITED AC 2008; 205:347-59. [PMID: 18208975 PMCID: PMC2271028 DOI: 10.1084/jem.20071243] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Monocyte chemoattractant protein-1 (MCP-1) directs migration of blood monocytes to inflamed tissues. Despite the central role of chemotaxis in immune responses, the regulation of chemotaxis by signal transduction pathways and their in vivo significance remain to be thoroughly deciphered. In this study, we examined the intracellular location and functions of two recently identified regulators of chemotaxis, Ca2+-independent phospholipase (iPLA2β) and cytosolic phospholipase (cPLA2α), and substantiate their in vivo importance. These enzymes are cytoplasmic in unstimulated monocytes. Upon MCP-1 stimulation, iPLA2β is recruited to the membrane-enriched pseudopod. In contrast, cPLA2α is recruited to the endoplasmic reticulum. Although iPLA2β or cPLA2α antisense oligodeoxyribonucleotide (ODN)–treated monocytes display reduced speed, iPLA2β also regulates directionality and actin polymerization. iPLA2β or cPLA2α antisense ODN–treated adoptively transferred mouse monocytes display a profound defect in migration to the peritoneum in vivo. These converging observations reveal that iPLA2β and cPLA2α regulate monocyte migration from different intracellular locations, with iPLA2β acting as a critical regulator of the cellular compass, and identify them as potential targets for antiinflammatory strategies.
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Affiliation(s)
- Ravi S Mishra
- Department of Cell Biology, Cleveland Clinic, Cleveland, OH 44195, USA
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27
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Syriani E, Gomez-Cabrero A, Bosch M, Moya A, Abad E, Gual A, Gasull X, Morales M. Profilin induces lamellipodia by growth factor-independent mechanism. FASEB J 2008; 22:1581-96. [PMID: 18184720 DOI: 10.1096/fj.06-7654com] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Profilin has been implicated in cell motility and in a variety of cellular processes, such as membrane extension, endocytosis, and formation of focal complexes. In vivo, profilin replenish the pool of ATP-actin monomers by increasing the rate of nucleotide exchange of ADP-actin for ATP-actin, promoting the incorporation of new actin monomers at the barbed end of actin filaments. For this report, we generated a membrane-permeable version of profilin I (PTD4-PfnI) for the alteration of intracellular profilin levels taking advantage of the protein transduction technique. We show that profilin I induces lamellipodia formation independently of growth factor presence in primary bovine trabecular meshwork (BTM) cells. The effects are time- and concentration-dependent and specific to the profilin I isoform. Profilin II, the neuronal isoform, failed to extend lamellipodia in the same degree as profilin I. H133S, a mutation in the polyproline binding domain, showed a reduced ability to induce lamellipodia. H199E, mutation in the actin binding domain failed to induce membrane spreading and inhibit fetal bovine serum (FBS) -induced lamellipodia extension. Incubation with a synthetic polyproline domain peptide (GP5)3, fused to a transduction domain, abolished lamellipodia induction by profilin or FBS. Time-lapse microscopy confirmed the effects of profilin on lamellipodia extension with a higher spreading velocity than FBS. PTD4-Pfn I was found in the inner lamellipodia domain, at the membrane leading edge where it colocalizes with endogenous profilin. While FBS-induced lamellipodia formation activates Rac1, PTD4-Pfn I stimulation did not induce Rac1 activation. We propose a role of profilin I favoring lamellipodia formation by a mechanism downstream of growth factor.
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Affiliation(s)
- Enrique Syriani
- IDIBAPS-Department of Physiological Sciences I, Facultad de Medicina-University of Barcelona, Barcelona, Spain
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28
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Abstract
Expression of profilin-1 (Pfn1) is downregulated in breast cancer cells, the functional significance of which is yet to be understood. To address this question, in this study we evaluated how perturbing Pfn1 affects motility and invasion of breast cancer cells. We show that loss of Pfn1 expression leads to enhanced motility and matrigel invasiveness of MDA-MB-231 breast cancer cells. Interestingly, silencing Pfn1 expression is associated with downregulation of both cell–cell and cell–matrix adhesions with concomitant increase in motility and dramatic scattering of normal human mammary epithelial cells. Thus, these data for the first time suggest that loss of Pfn1 expression may have significance in breast cancer progression. Consistent with these findings, even a moderate overexpression of Pfn1 induces actin stress-fibres, upregulates focal adhesion, and dramatically inhibits motility and matrigel invasiveness of MDA-MB-231 cells. Using mutants of Pfn1 that are defective in binding to either actin or proline-rich ligands, we further show that overexpressed Pfn1 must have a functional actin-binding site to suppress cell motility. Finally, animal experiments reveal that overexpression of Pfn1 suppresses orthotopic tumorigenicity and micro-metastasis of MDA-MB-231 cells in nude mice. These data imply that perturbing Pfn1 could be a good molecular strategy to limit the aggressiveness of breast cancer cells.
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29
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Abstract
Spines may undergo rapid, activity-dependent changes in shape and size, reflecting reorganization of the actin cytoskeleton. This remodeling is implicated in development and also in the late phase of long-term potentiation. However, the cellular mechanisms that convert activity into morphological change remain poorly understood, and little is known about the anatomical distribution of the actin-regulating proteins that mediate this remodeling. Using immunocytochemistry, we demonstrate here that cortactin (a protein implicated in actin filament nucleation, branching, and stabilization) is concentrated in hippocampal spines, where it colocalizes with F-actin. Cortactin has a Shank-binding domain; recent studies report that synaptic activity may trigger actin remodeling via this interaction with Shank. However, our immunogold electron microscopic data show that cortactin concentrates within the spine core, 100-150 nm away from the postsynaptic density (PSD); only a small fraction of the cortactin in spines lies adjacent to the PSD. These data suggest that the adult dendritic spine contains two functional pools of cortactin: a large pool in the spine core that may help to mediates changes in spine shape and a small synaptic pool that may modify the PSD in response to synaptic activity.
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Affiliation(s)
- Bence Racz
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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30
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Ethell IM, Pasquale EB. Molecular mechanisms of dendritic spine development and remodeling. Prog Neurobiol 2005; 75:161-205. [PMID: 15882774 DOI: 10.1016/j.pneurobio.2005.02.003] [Citation(s) in RCA: 264] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 01/28/2005] [Accepted: 02/22/2005] [Indexed: 12/19/2022]
Abstract
Dendritic spines are small protrusions that cover the surface of dendrites and bear the postsynaptic component of excitatory synapses. Having an enlarged head connected to the dendrite by a narrow neck, dendritic spines provide a postsynaptic biochemical compartment that separates the synaptic space from the dendritic shaft and allows each spine to function as a partially independent unit. Spines develop around the time of synaptogenesis and are dynamic structures that continue to undergo remodeling over time. Changes in spine morphology and density influence the properties of neural circuits. Our knowledge of the structure and function of dendritic spines has progressed significantly since their discovery over a century ago, but many uncertainties still remain. For example, several different models have been put forth outlining the sequence of events that lead to the genesis of a spine. Although spines are small and apparently simple organelles with a cytoskeleton mainly composed of actin filaments, regulation of their morphology and physiology appears to be quite sophisticated. A multitude of molecules have been implicated in dendritic spine development and remodeling, suggesting that intricate networks of interconnected signaling pathways converge to regulate actin dynamics in spines. This complexity is not surprising, given the likely importance of dendritic spines in higher brain functions. In this review, we discuss the molecules that are currently known to mediate the exquisite sensitivity of spines to perturbations in their environment and we outline how these molecules interface with each other to mediate cascades of signals flowing from the spine surface to the actin cytoskeleton.
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Affiliation(s)
- Iryna M Ethell
- Division of Biomedical Sciences, University of California Riverside, Riverside, CA 92521, USA
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31
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Roy P, Jacobson K. Overexpression of profilin reduces the migration of invasive breast cancer cells. ACTA ACUST UNITED AC 2004; 57:84-95. [PMID: 14691948 DOI: 10.1002/cm.10160] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The exact role profilin plays in cell migration is not clear. In this study, we have evaluated the effect of overexpression of profilin on the migration of breast cancer cells. Overexpression was carried out by stably expressing GFP-profilin in BT474 cells. It was observed that even a moderate level of overexpression of profilin significantly impaired the ability of BT474 cells to spread on fibronectin-coated substrate and migrate in response to EGF. GFP-profilin expressing cells also showed increased resistance to detachment in response to trypsin and increased tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin compared to the parental and GFP-expressing (control) cell lines. These results suggest that perturbation of profilin levels may offer a good strategy for controlling the metastatic potential of breast cancer cells.
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Affiliation(s)
- Partha Roy
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC, USA.
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32
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Lüscher B, Keller CA. Regulation of GABAA receptor trafficking, channel activity, and functional plasticity of inhibitory synapses. Pharmacol Ther 2004; 102:195-221. [PMID: 15246246 DOI: 10.1016/j.pharmthera.2004.04.003] [Citation(s) in RCA: 201] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Neural inhibition in the brain is mainly mediated by ionotropic gamma-aminobutyric acid type A (GABA(A)) receptors. Different subtypes of these receptors, distinguished by their subunit composition, are either concentrated at postsynaptic sites where they mediate phasic inhibition or found at perisynaptic and extrasynaptic locations where they prolong phasic inhibition and mediate tonic inhibition, respectively. Of special interest are mechanisms that modulate the stability and function of postsynaptic GABA(A) receptor subtypes and that are implicated in functional plasticity of inhibitory transmission in the brain. We will summarize recent progress on the classification of synaptic versus extrasynaptic receptors, the molecular composition of the postsynaptic cytoskeleton, the function of receptor-associated proteins in trafficking of GABA(A) receptors to and from synapses, and their role in post-translational signaling mechanisms that modulate the stability, density, and function of GABA(A) receptors in the postsynaptic membrane.
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Affiliation(s)
- Bernhard Lüscher
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA.
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33
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Ackermann M, Matus A. Activity-induced targeting of profilin and stabilization of dendritic spine morphology. Nat Neurosci 2003; 6:1194-200. [PMID: 14555951 DOI: 10.1038/nn1135] [Citation(s) in RCA: 212] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Accepted: 09/15/2003] [Indexed: 11/09/2022]
Abstract
Morphological changes in dendritic spines have been implicated in connective plasticity in brain circuitry, but the underlying pathway leading from synaptic transmission to structural change is unknown. Using primary neurons expressing GFP-tagged proteins, we found that profilin, a regulator of actin polymerization, is targeted to spine heads when postsynaptic NMDA receptors are activated and that actin-based changes in spine shape are concomitantly blocked. Profilin targeting was triggered by electrical stimulation patterns known to induce the long-term changes in synaptic responsiveness associated with memory formation. These results suggest that, in addition to electrophysiological changes, NMDA receptor activation initiates changes in the actin cytoskeleton of dendritic spines that stabilize synaptic structure.
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Bubb MR, Yarmola EG, Gibson BG, Southwick FS. Depolymerization of actin filaments by profilin. Effects of profilin on capping protein function. J Biol Chem 2003; 278:24629-35. [PMID: 12730212 DOI: 10.1074/jbc.m302796200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Profilin interacts with the barbed ends of actin filaments and is thought to facilitate in vivo actin polymerization. This conclusion is based primarily on in vitro kinetic experiments using relatively low concentrations of profilin (1-5 microm). However, the cell contains actin regulatory proteins with multiple profilin binding sites that potentially can attract millimolar concentrations of profilin to areas requiring rapid actin filament turnover. We have studied the effects of higher concentrations of profilin (10-100 microm) on actin monomer kinetics at the barbed end. Prior work indicated that profilin might augment actin filament depolymerization in this range of profilin concentration. At barbed-end saturating concentrations (final concentration, approximately 40 microm), profilin accelerated the off-rate of actin monomers by a factor of four to six. Comparable concentrations of latrunculin had no detectable effect on the depolymerization rate, indicating that profilin-mediated acceleration was independent of monomer sequestration. Furthermore, we have found that high concentrations of profilin can successfully compete with CapG for the barbed end and uncap actin filaments, and a simple equilibrium model of competitive binding could explain these effects. In contrast, neither gelsolin nor CapZ could be dissociated from actin filaments under the same conditions. These differences in the ability of profilin to dissociate capping proteins may explain earlier in vivo data showing selective depolymerization of actin filaments after microinjection of profilin. The finding that profilin can uncap actin filaments was not previously appreciated, and this newly discovered function may have important implications for filament elongation as well as depolymerization.
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Affiliation(s)
- Michael R Bubb
- The Research Service, Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida 32608, USA.
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35
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Zarrinpar A, Bhattacharyya RP, Lim WA. The Structure and Function of Proline Recognition Domains. Sci Signal 2003. [DOI: 10.1126/scisignal.1792003re8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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36
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Zarrinpar A, Bhattacharyya RP, Lim WA. The structure and function of proline recognition domains. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2003; 2003:RE8. [PMID: 12709533 DOI: 10.1126/stke.2003.179.re8] [Citation(s) in RCA: 221] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
One particularly abundant group of modular recognition domains consists of those that bind proline-rich motifs. Such modules, including the SH3, WW, and EVH1 domains, play a critical role in the assembly and regulation of many intracellular signaling complexes. These domains use strikingly similar molecular mechanisms of proline recognition. We discuss some of the potential biological advantages conferred by proline recognition, which may explain its widespread use in signaling.
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Affiliation(s)
- Ali Zarrinpar
- Program in Biological Sciences, University of California San Francisco, 600 16th Street, San Francisco, CA 94143-2240, USA
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37
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Hopmann R, Miller KG. A balance of capping protein and profilin functions is required to regulate actin polymerization in Drosophila bristle. Mol Biol Cell 2003; 14:118-28. [PMID: 12529431 PMCID: PMC140232 DOI: 10.1091/mbc.e02-05-0300] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Profilin is a well-characterized protein known to be important for regulating actin filament assembly. Relatively few studies have addressed how profilin interacts with other actin-binding proteins in vivo to regulate assembly of complex actin structures. To investigate the function of profilin in the context of a differentiating cell, we have studied an instructive genetic interaction between mutations in profilin (chickadee) and capping protein (cpb). Capping protein is the principal protein in cells that caps actin filament barbed ends. When its function is reduced in the Drosophila bristle, F-actin levels increase and the actin cytoskeleton becomes disorganized, causing abnormal bristle morphology. chickadee mutations suppress the abnormal bristle phenotype and associated abnormalities of the actin cytoskeleton seen in cpb mutants. Furthermore, overexpression of profilin in the bristle mimics many features of the cpb loss-of-function phenotype. The interaction between cpb and chickadee suggests that profilin promotes actin assembly in the bristle and that a balance between capping protein and profilin activities is important for the proper regulation of F-actin levels. Furthermore, this balance of activities affects the association of actin structures with the membrane, suggesting a link between actin filament dynamics and localization of actin structures within the cell.
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Affiliation(s)
- Roberta Hopmann
- Department of Biology, Washington University, St Louis, Missouri 63130, USA
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38
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Ji JY, Haghnia M, Trusty C, Goldstein LSB, Schubiger G. A genetic screen for suppressors and enhancers of the Drosophila cdk1-cyclin B identifies maternal factors that regulate microtubule and microfilament stability. Genetics 2002; 162:1179-95. [PMID: 12454065 PMCID: PMC1462342 DOI: 10.1093/genetics/162.3.1179] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Coordination between cell-cycle progression and cytoskeletal dynamics is important for faithful transmission of genetic information. In early Drosophila embryos, increasing maternal cyclin B leads to higher Cdk1-CycB activity, shorter microtubules, and slower nuclear movement during cycles 5-7 and delays in nuclear migration to the cortex at cycle 10. Later during cycle 14 interphase of six cycB embryos, we observed patches of mitotic nuclei, chromosome bridges, abnormal nuclear distribution, and small and large nuclei. These phenotypes indicate disrupted coordination between the cell-cycle machinery and cytoskeletal function. Using these sensitized phenotypes, we performed a dosage-sensitive genetic screen to identify maternal proteins involved in this process. We identified 10 suppressors classified into three groups: (1) gene products regulating Cdk1 activities, cdk1 and cyclin A; (2) gene products interacting with both microtubules and microfilaments, Actin-related protein 87C; and (3) gene products interacting with microfilaments, chickadee, diaphanous, Cdc42, quail, spaghetti-squash, zipper, and scrambled. Interestingly, most of the suppressors that rescue the astral microtubule phenotype also reduce Cdk1-CycB activities and are microfilament-related genes. This suggests that the major mechanism of suppression relies on the interactions among Cdk1-CycB, microtubule, and microfilament networks. Our results indicate that the balance among these different components is vital for normal early cell cycles and for embryonic development. Our observations also indicate that microtubules and cortical microfilaments antagonize each other during the preblastoderm stage.
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Affiliation(s)
- Jun-Yuan Ji
- Department of Zoology, University of Washington, Seattle 98195-1800, USA
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39
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Abstract
The functions of microtubules and actin filaments during various processes that are essential for the growth, reproduction and survival of single plant cells have been well characterized. A large number of plant structural cytoskeletal or cytoskeleton-associated proteins, as well as genes encoding such proteins, have been identified. Although many of these genes and proteins have been partially characterized with respect to their functions, a coherent picture of how they interact to execute cytoskeletal functions in plant cells has yet to emerge. Cytoskeleton-controlled cellular processes are expected to play crucial roles during plant cell differentiation and organogenesis, but what exactly these roles are has only been investigated in a limited number of studies in the whole plant context. The intent of this review is to discuss the results of these studies in the light of what is known about the cellular functions of the plant cytoskeleton, and about the proteins and genes that are required for them. Directions are outlined for future work to advance our understanding of how the cytoskeleton contributes to plant organogenesis and development.
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Affiliation(s)
- Benedikt Kost
- Laboratory of Plant Cell Biology, Institute of Molecular Biology, National University of Singapore, 1 Research Link, Singapore 117 604
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40
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Abstract
Peptide dendrimers are radial or wedge-like branched macromolecules consisting of a peptidyl branching core and/or covalently attached surface functional units. The multimeric nature of these constructs, the unambiguous composition and ease of production make this type of dendrimer well suited to various biotechnological and biochemical applications. Applications include use as biomedical diagnostic reagents, protein mimetics, anticancer and antiviral agents, vaccines and drug and gene delivery vehicles. This review focuses on the different types of peptide dendrimers currently in use and the synthetic methods commonly employed to generate peptide dendrimers ranging from stepwise solid-phase synthesis to chemoselective and orthogonal ligation.
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Affiliation(s)
- Kristen Sadler
- Department of Microbiology and Immunology, Vanderbilt University, Nashville, TN 37232, USA
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41
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Braun A, Aszódi A, Hellebrand H, Berna A, Fässler R, Brandau O. Genomic organization of profilin-III and evidence for a transcript expressed exclusively in testis. Gene 2002; 283:219-25. [PMID: 11867228 DOI: 10.1016/s0378-1119(01)00855-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Profilins are small, widely expressed actin binding proteins, thought to be key regulators of actin dynamics in living cells. So far, three profilin-genes have been described: profilin-I (PFN1), profilin-II (PFN2) with two splice variants and the recently identified profilin-III (PFN3). Here we describe the genomic organization of the genes encoding human and mouse profilin-III. Both are single exon genes and lie in close vicinity to the renal sodium-phosphate transport gene 2 (SLC34A1, NPT2) which is highly expressed in kidney. Northern hybridization to rat tissues has previously demonstrated expression of an approximately 4.5 kb long profilin-III mRNA transcript in kidney and a mRNA transcript of approximately 1 kb in length in testis. Here we show that mouse profilin-III expression is restricted to testis and that the 4.2 kb profilin-III mRNA in kidney is the result of a slc34a1 transcript which includes the antisense profilin-III open reading frame in its 3'-untranslated region. Finally, we demonstrate by in situ hybridization that profilin-III mRNA is localized to cells in the late stage of spermatogenesis.
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Affiliation(s)
- Attila Braun
- Department of Experimental Pathology, Lund University, S-22185, Lund, Sweden
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42
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Smith LC. The complement system in sea urchins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002; 484:363-72. [PMID: 11419003 DOI: 10.1007/978-1-4615-1291-2_35] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- L C Smith
- Department of Biological Sciences and Graduate Program in Genetics, George Washington University, Washington, DC, USA
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43
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Ravenall SJ, Gavazzi I, Wood JN, Akopian AN. A peripheral nervous system actin-binding protein regulates neurite outgrowth. Eur J Neurosci 2002; 15:281-90. [PMID: 11849295 DOI: 10.1046/j.0953-816x.2001.01862.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Difference cloning has identified a Villin-like mRNA transcript expressed selectively in peripheral sensory and sympathetic neurons. Pervin, the encoded 820-amino acid protein, has 60% identity with Villin and is the rat homologue of Advillin. Coimmunoprecipitation studies demonstrate that Pervin and actin interact in vivo. Transfection of COS-7 epithelial cell lines demonstrates colocalization of epitope-tagged Pervin with green fluorescent protein-actin and results in an increase in process formation. This effect is abolished when the putative actin-bundling headpiece of Pervin is deleted. Biolistic transfection of primary cultures of rat dorsal root ganglion sensory neurons also results in increased neurite outgrowth with FLAG-tagged Pervin. Deletion of the actin-bundling headpiece inhibits normal neurite growth. These data suggest that Pervin may play a significant role in regulating process outgrowth in peripheral neurons through a mechanism that involves the activity of an actin-bundling domain.
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Affiliation(s)
- Samantha J Ravenall
- Department of Biology, University College, Gower Street, London WC1E 6BT, UK
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44
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Ramachandran S, Christensen HE, Ishimaru Y, Dong CH, Chao-Ming W, Cleary AL, Chua NH. Profilin plays a role in cell elongation, cell shape maintenance, and flowering in Arabidopsis. PLANT PHYSIOLOGY 2000; 124:1637-47. [PMID: 11115881 PMCID: PMC59862 DOI: 10.1104/pp.124.4.1637] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2000] [Revised: 06/14/2000] [Accepted: 07/19/2000] [Indexed: 05/19/2023]
Abstract
Profilin (PFN) is an ubiquitous, low-M(r), actin-binding protein involved in the organization of the cytoskeleton of eukaryotes including higher plants. PFNs are encoded by a multigene family in Arabidopsis. We have analyzed in vivo functions of Arabidopsis PFN by generating transgenic plants carrying a 35S-PFN-1 or 35S-antisense PFN-1 transgene. Etiolated seedlings underexpressing PFN (PFN-U) displayed an overall dwarf phenotype with short hypocotyls whose lengths were 20% to 25% that of wild type (WT) at low temperatures. Light-grown PFN-U plants were smaller in stature and flowered early. Compared with equivalent cells in WT, most cells in PFN-U hypocotyls and roots were shorter, but more isodiametric, and microscopic observations of etiolated PFN-U hypocotyls revealed a rough epidermal surface. In contrast, light-grown seedlings overexpressing PFN had longer roots and root hair although etiolated seedlings overexpressing PFN were either the same size or slightly longer than WT seedlings. Transgenic seedlings harboring a PFN-1-GUS transgene directed expression in root and root hair and in a ring of cells at the elongating zone of the root tip. As the seedlings matured PFN-1-GUS was mainly expressed in the vascular bundles of cotyledons and leaves. Our results show that Arabidopsis PFNs play a role in cell elongation, cell shape maintenance, polarized growth of root hair, and unexpectedly, in determination of flowering time.
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Affiliation(s)
- S Ramachandran
- Laboratory of Plant Cell Biology, Institute of Molecular Agrobiology, National University of Singapore, 1 Research Link, Singapore 117604
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45
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Kneussel M, Betz H. Clustering of inhibitory neurotransmitter receptors at developing postsynaptic sites: the membrane activation model. Trends Neurosci 2000; 23:429-35. [PMID: 10941193 DOI: 10.1016/s0166-2236(00)01627-1] [Citation(s) in RCA: 224] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent studies indicate an important role of cytoskeleton-associated and lipid-anchored proteins in the formation of inhibitory postsynaptic membrane specializations. Membrane apposition of the tubulin-binding protein gephyrin is essential for the recruitment of inhibitory glycine receptors and GABAA receptors to developing postsynaptic sites. Newly disclosed interactions between gephyrin, exchange factors for G proteins of the Rho and Rac families, the translational regulator RAFT1, and actin-binding proteins like profilin might integrate activity-dependent and trophic-factor-mediated signals at developing postsynaptic sites. A model of inhibitory neurotransmitter receptor clustering, is proposed, in which this process is initiated by receptor-driven activation of phosphatidylinositol 3-kinase.
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Affiliation(s)
- M Kneussel
- Dept of Neurochemistry, Max-Planck-Institute for Brain Research, D-60528 Frankfurt/Main, Germany
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46
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DiNubile MJ, Huang S. Capping of the barbed ends of actin filaments by a high-affinity profilin-actin complex. CELL MOTILITY AND THE CYTOSKELETON 2000; 37:211-25. [PMID: 9227851 DOI: 10.1002/(sici)1097-0169(1997)37:3<211::aid-cm3>3.0.co;2-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Profilin, a ubiquitous 12 to 15-kDa protein, serves many functions, including sequestering monomeric actin, accelerating nucleotide exchange on actin monomers, decreasing the critical concentration of the barbed end of actin filaments, and promoting actin polymerization when barbed ends are free. Most previous studies have focused on profilin itself rather than its complex with actin. A high-affinity profilin-actin complex (here called profilactin) can be isolated from a poly-(L)-proline (PLP) column by sequential elution with 3 M and 7 M urea. Profilactin inhibited the elongation rate of pyrenyl-G-actin from filament seeds in a concentration- and time-dependent manner. Much greater inhibition of elongation was observed with spectrin-F-actin than gelsolin-F-actin seeds, suggesting that the major effect of profilactin was due to capping the barbed ends of actin filaments. Its dissociation constant for binding to filament ends was 0.3 microM; the on- and off-rate constants were estimated to be 1.7 x 10(3) M-1 s-1 and 4.5 x 10(-4) s-1, respectively. Purified profilin (obtained by repetitive applications to a PLP column and assessed by silver-stained polyacylamide gels) did not slow the elongation rate of pyrenyl-G-actin from filament seeds. Capping protein could not be detected by Western blotting in the profilactin preparation, but low concentrations of gelsolin did contaminate our preparation. However, prolonged incubation with either calcium or EGTA did not affect capping activity, implying that contaminating gelsolin-actin complexes were not primarily responsible for the observed capping activity. Reapplication of the profilactin preparation to PLP-coupled Sepharose removed both profilin and actin and concurrently eliminated its capping activity. Profilactin that was reapplied to uncoupled Sepharose retained its capping activity. Phosphatidylinositol-4,5-bisphosphate (PIP2) was the most potent phosphoinositol in reducing the capping activity of profilactin. Dissociation of the tight profilactin complex may serve as a unique mechanism by which profilin helps regulate actin filament growth.
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Affiliation(s)
- M J DiNubile
- Department of Medicine, Cooper Hospital/University Medical Center, UMDNJ/Robert Wood Johnson Medical School, Camden, USA.
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47
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Bubb MR, Baines IC, Korn ED. Localization of actobindin, profilin I, profilin II, and phosphatidylinositol-4,5-bisphosphate (PIP2) in Acanthamoeba castellanii. CELL MOTILITY AND THE CYTOSKELETON 2000; 39:134-46. [PMID: 9484955 DOI: 10.1002/(sici)1097-0169(1998)39:2<134::aid-cm4>3.0.co;2-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Specific polyclonal antisera were raised against purified Acanthamoeba actobindin and synthetic peptides corresponding to regions of maximum charge differences in Acanthamoeba profilin I and profilin II. Immunofluorescence studies with these antibodies showed profilin I to be distributed throughout the Acanthamoeba cytoplasm, except for lamellipodia, with the highest fluorescence intensity in cortical regions in which monomeric actin also was present, as shown by labeling with fluorescent DNase. In contrast, profilin II appeared to be uniformly associated with the plasma membrane except at sites of pseudopod extension, where the concentration was frequently decreased, in addition to cortical regions. Immunofluorescence studies using a monoclonal antibody specific for phosphatidylinositol-4,5-bisphosphate (PIP2) suggested that its distribution is mostly limited to the plasma membrane. In contrast to the distribution of profilin II, PIP2 immunofluorescence was prominent at the leading edge of cells, including the plasma membrane of lamellipodia. Quantitative immunoelectron microscopy showed that profilin II was approximately 36 times more likely to localize to the plasma membrane than profilin I. Immunofluorescence and confocal microscopy localized actobindin to the base of lamellipodia. The differential localization of the three actin monomer-binding proteins suggests that they have different biologic functions in Acanthamoeba and is consistent with the hypotheses that (1) profilin I functions predominantly as an actin monomer-binding protein; (2) profilin II regulates, or is regulated by, PIP2; and (3) actobindin inhibits nucleation of new filaments and facilitates elongation of existing polarized filaments in actively motile regions.
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Affiliation(s)
- M R Bubb
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-0301, USA
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48
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Mayboroda O, Schlüter K, Jockusch BM. Differential colocalization of profilin with microfilaments in PtK2 cells. CELL MOTILITY AND THE CYTOSKELETON 2000; 37:166-77. [PMID: 9186014 DOI: 10.1002/(sici)1097-0169(1997)37:2<166::aid-cm9>3.0.co;2-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Profilins are thought to be involved in the control of actin dynamics in eukaryotic cells. In accordance with this concept, profilin was found to be colocalized with the cortical microfilament webs in leading lamellae of locomoting and spreading fibroblasts. However, so far, there is little information on the distribution of profilin in other cell types. In this study, we report on the colocalization of profilin with various microfilament suprastructures in the epithelial cell line PtK2. This cell line, which is derived from rat kangaroo, contains a profilin sharing an N-terminal epitope with bovine and human profilin I, as seen by immunoblotting with monoclonal antibodies. By using immunofluorescence in conjunction with conventional fluorescence microscopy and confocal laser-scanning microscopy, we found profilin in ruffling areas of the peripheral lamellae and nascent stress fibers of spreading cells, whereas the peripheral belts of stationary cells growing in epithelioid sheets lacked profilin staining. In these cells, profilin was primarily distributed in a fine reticular or vesicular network that was not related to the microfilament system. Conspicuously low levels of profilins was not related to the contractile ring of mitotic cells. This was found for different fixation protocols and antibodies of the IgG and IgM type, respectively, indicating that lack of staining of the cleavage furrow was not due to antibody penetration problems. Depending on the fixation protocol, the nuclear matrix appeared strongly positive or negative for profilin. Cells microinjected with birch pollen profilin and labeled with a birch profilin-specific monoclonal antibody corroborated the results obtained with the endogeneous protein: The injected profilin was targeted to the cortical web and to nascent stress fibers of spreading cells but not to the cleavage ring of mitotic cells. These results suggest that high concentrations of a profilin I homologue are preferentially located with those microfilament suprastructures in PtK2 cells that are subject to rapid modulation by external signals.
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Affiliation(s)
- O Mayboroda
- Zoological Institute, Technical University of Braunschweig, Germany
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49
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Golla R, Philp N, Safer D, Chintapalli J, Hoffman R, Collins L, Nachmias VT. Co-ordinate regulation of the cytoskeleton in 3T3 cells overexpressing thymosin-beta4. CELL MOTILITY AND THE CYTOSKELETON 2000; 38:187-200. [PMID: 9331222 DOI: 10.1002/(sici)1097-0169(1997)38:2<187::aid-cm7>3.0.co;2-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In several cell types, short-term increases in the concentration of the G-actin-sequestering peptide thymosin-beta4 (Tbeta4) cause the disassembly of F-actin bundles. To determine the extent of cell adaptability to these reductions in F-actin, we overexpressed Tbeta4 in NIH 3T3 cells. In cell lines with Tbeta4 levels twice those of vector controls, G-actin increased approximately twofold as expected. However, F-actin did not decrease as in short-term experiments but rather also increased approximately twofold so that the G-F ratio remained constant. Surprisingly, the cytoskeletal proteins myosin IIA, alpha-actinin, and tropomyosin also increased nearly twofold. These increases were specific; DNA, total protein, lactic dehydrogenase, profilin, and actin depolymerizing factor levels were unchanged in the overexpressing cells. The Tbeta4 lines spread more fully and adhered to the dish more strongly than vector controls; this altered phenotype correlated with a twofold increase in talin and alpha5-integrin and a nearly threefold increase in vinculin. Focal adhesions, detected by indirect immunofluorescence with antivinculin, were increased in size over the controls. Northern blotting showed that mRNAs for both beta-actin and vinculin were increased twofold in the overexpressing lines. We conclude that 1) NIH 3T3 cells adapt to increased levels of G-actin sequestered by increased Tbeta4 by increasing their total actin so that the F-actin/G-actin ratio remains constant; 2) these cells coordinately increase several cytoskeletal and adhesion plaque proteins; and 3) at least for actin and vinculin, this regulation is at the transcriptional level. We therefore propose that the proteins of this multimember interacting complex making up the actin-based cytoskeleton, are coordinately regulated by factors that control the expression of several proteins. The mechanism may bear similarities to the control of synthesis of another multimember interacting complex, the myofibril of developing muscle cells.
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Affiliation(s)
- R Golla
- Department of Cell and Developmental Biology, School of Medicine, University of Pennsylvania, Philadelphia 19104, USA
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50
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Kneussel M, Betz H. Receptors, gephyrin and gephyrin-associated proteins: novel insights into the assembly of inhibitory postsynaptic membrane specializations. J Physiol 2000; 525 Pt 1:1-9. [PMID: 10811719 PMCID: PMC2269938 DOI: 10.1111/j.1469-7793.2000.t01-4-00001.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/1999] [Accepted: 02/16/2000] [Indexed: 11/30/2022] Open
Abstract
The synaptic localization of ion channel receptors is essential for efficient synaptic trans-mission and the precise regulation of diverse neuronal functions, such as signal integration and synaptic plasticity. Emerging evidence points to an important role of cytoskeleton-associated proteins that assemble receptors and components of the subsynaptic machinery at postsynaptic membrane specializations. This article reviews interactions of inhibitory postsynaptic neurotransmitter receptors with the receptor anchoring protein gephyrin and intracellular components involved in downstream signalling and/or control of signal transduction processes. The presently available data suggest a central synaptic organizer function for gephyrin in inhibitory postsynaptic membrane assembly and stabilization.
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Affiliation(s)
- M Kneussel
- Department of Neurochemistry, Max Planck Institute for Brain Research, Deutschordenstrasse 46, D-60528 Frankfurt/Main, Germany
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