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Han X, Hu Z, Surya W, Ma Q, Zhou F, Nordenskiöld L, Torres J, Lu L, Miao Y. The intrinsically disordered region of coronins fine-tunes oligomerization and actin polymerization. Cell Rep 2023; 42:112594. [PMID: 37269287 DOI: 10.1016/j.celrep.2023.112594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 04/21/2023] [Accepted: 05/16/2023] [Indexed: 06/05/2023] Open
Abstract
Coronins play critical roles in actin network formation. The diverse functions of coronins are regulated by the structured N-terminal β propeller and the C-terminal coiled coil (CC). However, less is known about a middle "unique region" (UR), which is an intrinsically disordered region (IDR). The UR/IDR is an evolutionarily conserved signature in the coronin family. By integrating biochemical and cell biology experiments, coarse-grained simulations, and protein engineering, we find that the IDR optimizes the biochemical activities of coronins in vivo and in vitro. The budding yeast coronin IDR plays essential roles in regulating Crn1 activity by fine-tuning CC oligomerization and maintaining Crn1 as a tetramer. The IDR-guided optimization of Crn1 oligomerization is critical for F-actin cross-linking and regulation of Arp2/3-mediated actin polymerization. The final oligomerization status and homogeneity of Crn1 are contributed by three examined factors: helix packing, the energy landscape of the CC, and the length and molecular grammar of the IDR.
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Affiliation(s)
- Xiao Han
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Zixin Hu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Wahyu Surya
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Qianqian Ma
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Feng Zhou
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Lars Nordenskiöld
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Jaume Torres
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore; Institute for Digital Molecular Analytics and Science, Nanyang Technological University, Singapore 636921, Singapore.
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2
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Skorokhod OA, Barrera V, Heller R, Carta F, Turrini F, Arese P, Schwarzer E. Malarial pigment hemozoin impairs chemotactic motility and transendothelial migration of monocytes via 4-hydroxynonenal. Free Radic Biol Med 2014; 75:210-21. [PMID: 25017964 DOI: 10.1016/j.freeradbiomed.2014.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 06/25/2014] [Accepted: 07/03/2014] [Indexed: 12/24/2022]
Abstract
Natural hemozoin, nHZ, is avidly phagocytosed in vivo and in vitro by human monocytes. The persistence of the undigested β-hematin core of nHZ in the phagocyte lysosome for long periods of time modifies several cellular immune functions. Here we show that nHZ phagocytosis by human primary monocytes severely impaired their chemotactic motility toward MCP-1, TNF, and FMLP, by approximately 80% each, and their diapedesis across a confluent human umbilical vein endothelial cell layer toward MCP-1 by 45±5%. No inhibition was observed with latex-fed or unfed monocytes. Microscopic inspection revealed polarization defects in nHZ-fed monocytes due to irregular actin polymerization. Phagocytosed nHZ catalyzes the peroxidation of polyunsaturated fatty acids and generation of the highly reactive derivative 4-hydroxynonenal (4-HNE). Similar to nHZ phagocytosis, the exposure of monocytes to in vivo-compatible 4-HNE concentrations inhibited cell motility in both the presence and the absence of chemotactic stimuli, suggesting severe impairment of cytoskeleton dynamics. Consequently, 4-HNE conjugates with the cytoskeleton proteins β-actin and coronin-1A were immunochemically identified in nHZ-fed monocytes and mass spectrometrically localized in domains of protein-protein interactions involved in cytoskeleton reorganization and cell motility. The molecular and functional modifications of actin and coronin by nHZ/4-HNE may also explain impaired phagocytosis, another motility-dependent process previously described in nHZ-fed monocytes. Further studies will show whether impaired monocyte motility may contribute to the immunodepression and the frequent occurrence of secondary infections observed in malaria patients.
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Affiliation(s)
| | | | - Regine Heller
- Institute for Molecular Cell Biology, Center for Molecular Biomedicine, Friedrich Schiller University of Jena, 07745 Jena, Germany
| | | | - Franco Turrini
- Department of Oncology, University of Torino, 10126 Torino, Italy
| | - Paolo Arese
- Department of Oncology, University of Torino, 10126 Torino, Italy
| | - Evelin Schwarzer
- Department of Oncology, University of Torino, 10126 Torino, Italy.
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Oku T, Nakano M, Kaneko Y, Ando Y, Kenmotsu H, Itoh S, Tsuiji M, Seyama Y, Toyoshima S, Tsuji T. Constitutive turnover of phosphorylation at Thr-412 of human p57/coronin-1 regulates the interaction with actin. J Biol Chem 2012; 287:42910-20. [PMID: 23100250 DOI: 10.1074/jbc.m112.349829] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The actin-binding protein p57/coronin-1, a member of the coronin protein family, is selectively expressed in hematopoietic cells and plays crucial roles in the immune response through reorganization of the actin cytoskeleton. We previously reported that p57/coronin-1 is phosphorylated by protein kinase C, and the phosphorylation down-regulates the association of this protein with actin. In this study we analyzed the phosphorylation sites of p57/coronin-1 derived from HL60 human leukemic cells by MALDI-TOF-MS, two-dimensional gel electrophoresis, and Phos-tag® acrylamide gel electrophoresis in combination with site-directed mutagenesis and identified Ser-2 and Thr-412 as major phosphorylation sites. A major part of p57/coronin-1 was found as an unphosphorylated form in HL60 cells, but phosphorylation at Thr-412 of p57/coronin-1 was detected after the cells were treated with calyculin A, a Ser/Thr phosphatase inhibitor, suggesting that p57/coronin-1 undergoes constitutive turnover of phosphorylation/dephosphorylation at Thr-412. A diphosphorylated form of p57/coronin-1 was detected after the cells were treated with phorbol 12-myristate 13-acetate plus calyculin A. We then assessed the effects of phosphorylation at Thr-412 on the association of p57/coronin-1 with actin. A co-immunoprecipitation experiment with anti-p57/coronin-1 antibodies and HL60 cell lysates revealed that β-actin was co-precipitated with the unphosphorylated form but not with the phosphorylated form at Thr-412 of p57/coronin-1. Furthermore, the phosphorylation mimic (T412D) of p57/coronin-1 expressed in HEK293T cells exhibited lower affinity for actin than the wild-type or the unphosphorylation mimic (T412A) did. These results indicate that the constitutive turnover of phosphorylation at Thr-412 of p57/coronin-1 regulates its interaction with actin.
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Affiliation(s)
- Teruaki Oku
- Department of Microbiology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Tokyo 142-8501, Japan
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4
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Abstract
Dynamic rearrangement of actin filament networks is critical for cell motility, phagocytosis and endocytosis. Coronins facilitate these processes, in part, by their ability to bind F-actin (filamentous actin). We previously identified a conserved surface-exposed arginine (Arg30) in the β-propeller of Coronin 1B required for F-actin binding in vitro and in vivo. However, whether this finding translates to other coronins has not been well defined. Using quantitative actin-binding assays, we show that mutating the equivalent residue abolishes F-actin binding in Coronin 1A, but not Coronin 1C. By mutagenesis and biochemical competition, we have identified a second actin-binding site in the unique region of Coronin 1C. Interestingly, leading-edge localization of Coronin 1C in fibroblasts requires the conserved site in the β-propeller, but not the site in the unique region. Furthermore, in contrast with Coronin 1A and Coronin 1B, Coronin 1C displays highly co-operative binding to actin filaments. In the present study, we highlight a novel mode of coronin regulation, which has implications for how coronins orchestrate cytoskeletal dynamics.
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Xavier CP, Rastetter RH, Blömacher M, Stumpf M, Himmel M, Morgan RO, Fernandez MP, Wang C, Osman A, Miyata Y, Gjerset RA, Eichinger L, Hofmann A, Linder S, Noegel AA, Clemen CS. Phosphorylation of CRN2 by CK2 regulates F-actin and Arp2/3 interaction and inhibits cell migration. Sci Rep 2012; 2:241. [PMID: 22355754 PMCID: PMC3268813 DOI: 10.1038/srep00241] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 12/20/2011] [Indexed: 01/27/2023] Open
Abstract
CRN2 (synonyms: coronin 1C, coronin 3) functions in the re-organization of the actin network and is implicated in cellular processes like protrusion formation, secretion, migration and invasion. We demonstrate that CRN2 is a binding partner and substrate of protein kinase CK2, which phosphorylates CRN2 at S463 in its C-terminal coiled coil domain. Phosphomimetic S463D CRN2 loses the wild-type CRN2 ability to inhibit actin polymerization, to bundle F-actin, and to bind to the Arp2/3 complex. As a consequence, S463D mutant CRN2 changes the morphology of the F-actin network in the front of lamellipodia. Our data imply that CK2-dependent phosphorylation of CRN2 is involved in the modulation of the local morphology of complex actin structures and thereby inhibits cell migration.
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Affiliation(s)
- Charles-Peter Xavier
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931, Cologne, Germany
- Both authors contributed equally to this work
- Present address: Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4256, USA
| | - Raphael H. Rastetter
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931, Cologne, Germany
- Both authors contributed equally to this work
| | - Margit Blömacher
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931, Cologne, Germany
| | - Maria Stumpf
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931, Cologne, Germany
| | - Mirko Himmel
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Reginald O. Morgan
- Department of Biochemistry and Molecular Biology, University of Oviedo and University Institute of Biotechnology of Asturias, Oviedo, 33006, Spain
| | - Maria-Pilar Fernandez
- Department of Biochemistry and Molecular Biology, University of Oviedo and University Institute of Biotechnology of Asturias, Oviedo, 33006, Spain
| | - Conan Wang
- Structural Chemistry, Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane, Qld 4111, Australia
| | - Asiah Osman
- Structural Chemistry, Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane, Qld 4111, Australia
| | - Yoshihiko Miyata
- Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan
| | - Ruth A. Gjerset
- Torrey Pines Institute for Molecular Studies, San Diego, California, 92121, USA
| | - Ludwig Eichinger
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931, Cologne, Germany
| | - Andreas Hofmann
- Structural Chemistry, Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane, Qld 4111, Australia
| | - Stefan Linder
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Angelika A. Noegel
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931, Cologne, Germany
| | - Christoph S. Clemen
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931, Cologne, Germany
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An essential role for RIG-I in toll-like receptor-stimulated phagocytosis. Cell Host Microbe 2009; 6:150-61. [PMID: 19683681 DOI: 10.1016/j.chom.2009.06.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 02/03/2009] [Accepted: 06/12/2009] [Indexed: 11/21/2022]
Abstract
Retinoic acid-inducible gene-I (RIG-I) plays an important role in antiviral response by recognizing double-stranded RNA. Here we demonstrate an unanticipated role of RIG-I in Toll-like receptor (TLR)-stimulated phagocytosis. Stimulation with lipopolysaccharide (LPS), a ligand of TLR4, induced the expression of RIG-I in macrophages. Depletion of RIG-I by RNAi or gene targeting inhibited the LPS-induced phagocytosis of bacteria. Cellular processes involved in phagocytosis, such as small GTPase Cdc42/Rac1 activation, actin polymerization, and actin-regulator Arp2/3 recruitment, were also impaired in RIG-I-deficient macrophages activated by LPS. Moreover, RIG-I(-/-) mice were found to be more susceptible to infection with Escherichia coli as compared to wild-type mice. Thus, the regulatory functions of RIG-I are strikingly broad, including a role not only in antiviral responses but in antibacterial responses as well.
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7
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Coronin switches roles in actin disassembly depending on the nucleotide state of actin. Mol Cell 2009; 34:364-74. [PMID: 19450534 DOI: 10.1016/j.molcel.2009.02.029] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 11/26/2008] [Accepted: 02/25/2009] [Indexed: 10/20/2022]
Abstract
Rapid and polarized turnover of actin networks is essential for motility, endocytosis, cytokinesis, and other cellular processes. However, the mechanisms that provide tight spatiotemporal control of actin disassembly remain poorly understood. Here, we show that yeast coronin (Crn1) makes a unique contribution to this process by differentially interacting with and regulating the effects of cofilin on ATP/ADP+P(i) versus ADP actin filaments. Crn1 potently blocks cofilin severing of newly assembled (ATP/ADP+P(i)) filaments but synergizes with cofilin to sever older (ADP) filaments. Thus, Crn1 has qualitatively distinct/opposite effects on actin dynamics depending on the nucleotide state of actin. This bimodal mechanism requires two separate actin-binding domains in Crn1. Consistent with these activities, Crn1 excludes GFP-Cof1 from newly assembled regions of actin networks in vivo and accelerates cellular actin turnover by four fold. We conclude that coronin polarizes the spatial distribution and activity of cofilin to promote selective disassembly of older actin filaments.
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8
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Abstract
Until recently, structural information about coronins was scarce and the earlier identification of five WD40 repeats gave rise to a structural prediction of a five-bladed beta propeller for the N-terminal domain of these proteins. More detailed analyses revealed the presence of seven WD40 repeats and the hypothesis of a seven-bladed beta propeller structure. This model has recently been validated due to structural information from crystal structures of C-terminally truncated coronin 1 (1A), as well as its C-terminal coiled coil domain. Further structural information is available only indirectly from binding and functional studies.Phosphorylation at distinct serine and tyrosine residues seems to be a common theme for various coronins. There are indications that this modification regulates the quaternary structure of coronin 3 (1C) and thus has implications for the cellular localisation and the general link between signalling and cytoskeletal remodelling. Similarly, phosphorylation-dependent sorting sequences recently discovered on coronin 7 might prove important for the molecular mechanisms of the longer coronins.A matter that will require further clarification is the localisation of protein binding sites on coronins. While earlier reports presented a rather diverse map of actin binding sites, more recent studies, including the crystal structure of the coronin 1 N-terminal domain, deliver more detailed information in this respect. Interaction sites for other target proteins, such as Arp2/3, remain to be identified. Also, while membrane binding is a known feature of coronins, further details as to the binding sites and molecular level events remain to be elucidated. The N-terminal WD40 repeat domain seems to be the membrane-interacting domain, but other domains might provide regulatory effects, most likely by posttranslational modification, in a fashion that is specific for each coronin.In this chapter, we provide a structural overview of coronins 1 (1A), 2 (1B), 3 (1C) and 7 and also present results of our recent efforts to obtain structural models of coronins 3 and 7. Possible implications of these models on the function of these proteins are discussed.
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9
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Abstract
Most coronin proteins rely on interaction with actin in their functions. Mammalian coronin 7 has not been shown to interact with actin, but rather to bind to the outer side of Golgi complex membranes. Targeting of coronin 7 to Golgi membranes requires the activity of Src kinase and integrity of AP-1 adaptor protein complex. Coronin 7 further physically interacts with both AP-1 and Src in vivo and in vitro and is phosphorylated by Src. Depletion of coronin 7 by RNAi results in Golgi breakdown and accumulation of arrested cargo proteins, suggesting the protein functions in the later stages of cargo sorting and export from the Golgi complex. We suggest that coronin 7 acts as a mediator of cargo vesicle formation at the trans-Golgi network (TGN) downstream of AP-1 interaction with cargo but upstream of protein kinase D dependent membrane fission.
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Affiliation(s)
- Vasily Rybakin
- The Scripps Research Institute, 10550 N Torrey Pines Road, La Jolla, CA 92037, USA.
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10
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Abstract
Coronin is a conserved actin binding protein that promotes cellular processes that rely on rapid remodeling of the actin cytoskeleton, including endocytosis and cell motility. However, the exact mechanism by which coronin contributes to actin dynamics has remained elusive for many years. Here, we integrate observations from many groups and propose a unified model to explain how coronin controls actin dynamics through coordinated effects on Arp2/3 complex and cofilin. At the front end of actin networks, coronin protects new (ATP-rich) filaments from premature disassembly by cofilin and recruits Arp2/3 complex to filament sides, leading to nucleation, branching and network expansion. At the rear of networks, coronin has strikingly different activities, synergizing with cofilin to dismantle old (ADP-rich) filaments. Thus, coronin spatially targets Arp2/3 complex and cofilin to opposite ends of actin networks. The net effect of coronin's activities is acceleration of polarized actin subunit flux through filamentous arrays. This increases actin network plasticity and replenishes the actin monomer pool required for new filament growth.
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Affiliation(s)
- Meghal Gandhi
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA
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11
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Galkin VE, Orlova A, Brieher W, Kueh HY, Mitchison TJ, Egelman EH. Coronin-1A stabilizes F-actin by bridging adjacent actin protomers and stapling opposite strands of the actin filament. J Mol Biol 2007; 376:607-13. [PMID: 18177666 DOI: 10.1016/j.jmb.2007.12.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Revised: 11/28/2007] [Accepted: 12/04/2007] [Indexed: 11/28/2022]
Abstract
Coronins are F-actin-binding proteins that are involved, in concert with Arp2/3, Aip1, and ADF/cofilin, in rearrangements of the actin cytoskeleton. An understanding of coronin function has been hampered by the absence of any structural data on its interaction with actin. Using electron microscopy and three-dimensional reconstruction, we show that coronin-1A binds to three protomers in F-actin simultaneously: it bridges subdomain 1 and subdomain 2 of two adjacent actin subunits along the same long-pitch strand, and it staples subdomain 1 and subdomain 4 of two actin protomers on different strands. Such a mode of binding explains how coronin can stabilize actin filaments in vitro. In addition, we show which residues of F-actin may participate in the interaction with coronin-1A. Human nebulin and Xin, as well as Salmonella invasion protein A, use a similar mechanism to stabilize actin filaments. We suggest that the stapling of subdomain 1 and subdomain 4 of two actin protomers on different strands is a common mechanism for F-actin stabilization utilized by many actin-binding proteins that have no homology.
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Affiliation(s)
- Vitold E Galkin
- Department of Biochemistry and Molecular Genetics, University of Virginia, Box 800733, Charlottesville, VA 22908-0733, USA.
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Gaidos G, Soni S, Oswald DJ, Toselli PA, Kirsch KH. Structure and function analysis of the CMS/CIN85 protein family identifies actin-bundling properties and heterotypic-complex formation. J Cell Sci 2007; 120:2366-77. [PMID: 17606992 DOI: 10.1242/jcs.004333] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Members of the CMS/CIN85 protein family participate in clathrin-mediated endocytosis and play a crucial role in maintaining the kidney filtration barrier. The CMS protein structure includes three Src homology 3 (SH3) domains and a proline-rich (PR) region that is connected by a `linker' sequence to a coiled-coil (CC) domain. We show that CMS is a component of special actin-rich adhesion structures – podosomes – and demonstrate specific actin-binding properties of CMS. We have found that the entire C-terminal half of CMS is necessary for efficient binding to filamentous actin (F-actin). CMS and CIN85 can crosslink F-actin into bundles, a function that depends on the PR region and the CC domain. Removal of these domains reduces migration. CMS can also form heterotypic complexes with CIN85. CIN85 is expressed as multiple isoforms that share the CC domain, suggesting that heterotypic interactions with CMS provides a mechanism to regulate CMS binding to F-actin and thus for modulating dynamic rearrangements of the cytoskeleton.
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Affiliation(s)
- Gabriel Gaidos
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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Yan M, Di Ciano-Oliveira C, Grinstein S, Trimble WS. Coronin function is required for chemotaxis and phagocytosis in human neutrophils. THE JOURNAL OF IMMUNOLOGY 2007; 178:5769-78. [PMID: 17442961 DOI: 10.4049/jimmunol.178.9.5769] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Coronins are a family of conserved actin-associated proteins that have been implicated in a variety of cellular processes dependent on actin rearrangements. In this study, we show that in primary human neutrophils, coronins-1-4 and -7 are expressed. Coronin-1 accumulates at the leading edge of migrating neutrophils and at the nascent phagosome. Inhibition of coronin function by transduction of a dominant-negative form of the protein leads to inhibition of chemotaxis and a reduction in neutrophil spreading and adhesion. This inhibition appears to correlate with changes in the distribution of F-actin structures within the cell. In addition, phagocytosis is inhibited, but neither secretion nor activation of the NADPH oxidase appears to be affected. Together, these results show that coronins are required for actin-dependent changes in cell morphology that lead to migration and phagocytosis.
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Affiliation(s)
- Ming Yan
- Programme in Cell Biology, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada
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14
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Abstract
Coronins are conserved F-actin binding proteins that have been implicated in a variety of processes including fibroblast migration, phagocytosis, and chemotaxis. Recent data from our lab indicate that coronin 1B coordinates Arp2/3-dependent actin filament nucleation and cofilin-mediated filament turnover at the leading edge of migrating fibroblasts. Analysis of coronin function has been hampered by the lack of a clear understanding of how coronin interacts with F-actin. Here, we identify a surface-exposed conserved arginine residue at position 30 (R30), which is crucial for coronin 1B binding to F-actin both in vitro and in vivo. Using actin co-sedimentation, we demonstrate that coronin 1B binds with high affinity to ATP/ADP-P(i)-F-actin (170 nM) and with 47-fold lower affinity to ADP-F-actin (8 microM). In contrast to a previous study, we find no evidence for enhanced cofilin binding to F-actin in the presence of either coronin 1B or coronin 1A. Instead, we find that coronin 1B protects actin filaments from cofilin-induced depolymerization. Consistent with an important role for interactions between coronin 1B and F-actin in vivo, an R30D coronin mutant that does not bind F-actin localizes inefficiently to the leading edge. Furthermore, our analysis indicates that F-actin binding is absolutely required for coronin 1B to exert its effects on whole-cell motility and lamellipodial dynamics.
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Affiliation(s)
- Liang Cai
- Lineberger Comprehensive Cancer Center, Department of Cell & Developmental Biology, University of North Carolina at Chapel Hill, North Carolina 27599-7295, USA
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