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Eisermann I, Garduño‐Rosales M, Talbot NJ. The emerging role of septins in fungal pathogenesis. Cytoskeleton (Hoboken) 2023; 80:242-253. [PMID: 37265147 PMCID: PMC10952683 DOI: 10.1002/cm.21765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 05/13/2023] [Accepted: 05/16/2023] [Indexed: 06/03/2023]
Abstract
Fungal pathogens undergo specific morphogenetic transitions in order to breach the outer surfaces of plants and invade the underlying host tissue. The ability to change cell shape and switch between non-polarised and polarised growth habits is therefore critical to the lifestyle of plant pathogens. Infection-related development involves remodelling of the cytoskeleton, plasma membrane and cell wall at specific points during fungal pathogenesis. Septin GTPases are components of the cytoskeleton that play pivotal roles in actin remodelling, micron-scale plasma membrane curvature sensing and cell polarity. Septin assemblages, such as rings, collars and gauzes, are known to have important roles in cell shape changes and are implicated in formation of specialised infection structures to enter plant cells. Here, we review and compare the reported functions of septins of plant pathogenic fungi, with a special focus on invasive growth. Finally, we discuss septins as potential targets for broad-spectrum antifungal plant protection strategies.
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Affiliation(s)
- Iris Eisermann
- The Sainsbury LaboratoryUniversity of East AngliaNorwichUK
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2
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Zarubina KI, Parovichnikova EN, Surin VL, Pshenichnikova OS, Gavrilina OA, Isinova GA, Troitskaia VV, Sokolov AN, Gal'tseva IV, Kapranov NM, Davydova IO, Obukhova TN, Sudarikov AB, Savchenko VG. [Detection of activating mutations in RAS/RAF/MEK/ERK and JAK/STAT signaling pathways]. TERAPEVT ARKH 2020; 92:31-42. [PMID: 33346443 DOI: 10.26442/00403660.2020.07.000772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Indexed: 11/22/2022]
Abstract
ISSUE The study of activating mutations (NRAS,KRAS,FLT3,JAK2,CRLF2genes) of RAS/RAF/MEK/ERK and JAK/STAT signaling pathways in B-cell acute lymphoblastic leukemia (B-ALL) in adult patients which are included in Russian multicenter clinical trials. MATERIALS AND METHODS Within the multicenter study there were 119 adult patients included withde novoB-ALL. The study was considered as prospective and retrospective. The group withBCR-ABL1-negative B-ALL consisted of up to 93 patients (45 male and 48 female, at the age of 17 to 59, the median age 31), they were treated according to the protocols ALL-2009, ALL-2016. The median follow-up lasted for 19 months (1119). The group withBCR-ABL1-positive B-ALL with up to 26 patients (10 male and 16 female, at the age of 23 to 78, the median age 34 years) was included in the study as well. The treatment was carried out according to the protocols ALL-2009 and ALL-2012 in combination with tyrosine kinase inhibitors. The median follow-up lasted for 23 months (4120). The molecular analysis of activating mutations inNRAS,KRASgenes (RAS/RAF/MEK/ERK signaling pathway) andJAK2,CRLF2genes (JAK/STAT signaling cascade) was performed via Sanger sequencing. The internal tandem duplications (ITDs) inFLT3gene were studied by fragment analysis. The evaluation of CRLF2 expression was fulfilled via flow cytometry. RESULTS Activating mutations inNRAS,KRAS,FLT3genes were found in 22 (23.6%) patients withBCR-ABL1-negative B-ALL. In total, 23 mutations were revealed in theNRAS(n=9),KRAS(n=12), andFLT3(n=2) genes, according to statistics that was significantly more frequent than withBCR-ABL1-positive B-ALL, these genes mutations were not identified in patients (p=0.007). The frequency of mutations detection inKRASandNRASgenes in patients withBCR-ABL1-negative B-ALL was comparable as 12.9% (12 of 93) to 9.7% (9 of 93), respectively (p=0.488). One patient was simultaneously revealed 2 mutations in theKRASgene (in codons 13 and 61).FLT3-ITD mutations were detected in 3.5% (2 of 57) cases ofBCR-ABL1-negative B-ALL. In patients withBCR-ABL1-positive B-ALLFLT3-ITD mutations were not assessed. Violations in the JAK/STAT signaling cascade were detected in 4 (4.3%) patients withBCR-ABL1-negative B-ALL. They were represented by the missense mutations ofJAK2gene (n=3) and the overexpression of CRLF2 (n=2); in one patient were detected the overexpression of CRLF2 and a mutation inJAK2gene simultaneously. No mutations were found inCRLF2gene. In patients withBCR-ABL1-positive B-ALL noJAK2mutations were detected. As long as analyzing demographic and clinical laboratory parameters between groups of patients with and without mutations, there were no statistically significant differences obtained. In the analyzed groups of patients, long-term therapy results did not differentiate according to the mutations presence inNRAS,KRAS,FLT3,JAK2genes. Also, substantive differences were not shown in the rate of the negative status achievement of the minimum residual disease between patients with and without activating mutations in the control points of the protocol (on the 70th, 133rd and 190th days). CONCLUSION NRAS,KRAS,FLT3,JAK2activating mutations do not affect the long-term results of the therapy and the rate of the negative status achievement of the minimum residual disease in patients withBCR-ABL1-negative B-ALL treated by the Russian multicenter clinical trials.
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Affiliation(s)
| | | | - V L Surin
- National Research Center for Hematology
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Ok F, Kaplan HM, Kizilgok B, Demir E. Protective effect of Alpha-Linolenic acid on Lipopolysaccharide-Induced Orchitis in mice. Andrologia 2020; 52:e13667. [PMID: 32453444 DOI: 10.1111/and.13667] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/05/2020] [Accepted: 05/07/2020] [Indexed: 01/05/2023] Open
Abstract
Previous studies have demonstrated that polyunsaturated fatty acids (PUFAs) have anti-inflammatory effects. One specific PUFA, alpha-linolenic acid (ALA), shows both anti-inflammatory and antioxidant properties. In the testes, inflammatory mediators are known to increase when orchitis is induced by bacterial lipopolysaccharide (LPS). This study aimed to determine whether the anti-inflammatory properties of ALA could have a protective effect against LPS-induced orchitis in mice. The mice were divided into untreated control, orchitis and ALA-treated orchitis groups. Orchitis was induced by intraperitoneal injection of LPS. The ALA-treated group was administered ALA by gavage three days before intraperitoneal LPS injection. Cyclooxygenase-2 (COX-2), cytosolic phospholipase A2 (cPLA2), inducible nitric oxide synthase (iNOS) enzymes and nuclear factor kappa-B (NF-κB) in the testes, as well as serum interleukin 6 (IL-6) and tumour necrosis factor-alpha (TNF-α), were analysed using enzyme-linked immunosorbent assay (ELISA) tests. LPS administration increased the expression of several inflammatory mediators, including IL-6, TNF-α and NF-κB, as well as the COX-2, cPLA2 and iNOS enzymes. ALA administration significantly prevented the LPS-induced increases in these inflammatory mediators and enzymes (p < .05). The anti-inflammatory and antioxidant effects of ALA may make it a useful candidate for the treatment of orchitis caused by bacterial LPS.
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Affiliation(s)
- Fesih Ok
- Urology Department, Siirt State Hospital, Siirt, Turkey
| | - Halil Mahir Kaplan
- Pharmacology Department, Cukurova University Medical Faculty, Adana, Turkey
| | | | - Erkan Demir
- Urology Department, Cukurova University Medical Faculty, Adana, Turkey
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Liu XH, Ma J, Feng JX, Feng Y, Zhang YF, Liu LX. Regulation and related mechanism of GSN mRNA level by hnRNPK in lung adenocarcinoma cells. Biol Chem 2019; 400:951-963. [PMID: 30771276 DOI: 10.1515/hsz-2018-0417] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 02/11/2019] [Indexed: 01/20/2023]
Abstract
Gelsolin (GSN) is an actin filament-capping protein that plays a key role in cell migration. Here we show that heterogeneous nuclear ribonucleoprotein K (hnRNPK) regulates GSN expression level by binding to the 3'-untranslated region (3'UTR) of GSN mRNA in non-small cell lung cancers (NSCLC) H1299 cells which are highly metastatic and express high level of GSN. We found that hnRNPK overexpression increased the mRNA and protein level of GSN, whereas hnRNPK knockdown by siRNA decreased the mRNA and protein level of GSN in both H1299 and A549 cells, indicating a positive role of hnRNPK in the regulation of GSN expression. Furthermore, hnRNPK knockdown affected the migration ability of H1299 and A549 cells which could be rescued by ectopic expression of GSN in those cells. Conversely, GSN knockdown in hnRNPK-overexpressing cells could abort the stimulatory effect of hnRNPK on the cell migration. These results suggest that hnRNPK function in the regulation of cell migration is GSN-dependent. Taken together, these data unveiled a new mechanism of regulation of the GSN expression by hnRNPK and provides new clues for the discovery of new anti-metastatic therapy.
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Affiliation(s)
- Xiao-Hui Liu
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Jie Ma
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Jun-Xia Feng
- Department of Nephrology, Huadu District People's Hospital of Guangzhou, Southern Medical University, Guangzhou 510800, China
| | - Yuan Feng
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Yun-Fang Zhang
- Department of Nephrology, Huadu District People's Hospital of Guangzhou, Southern Medical University, Guangzhou 510800, China
| | - Lang-Xia Liu
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
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Abstract
Gelsolin (GSN), one of the most abundant actin-binding proteins, is involved in cell motility, shape and metabolism. As a member of the GSN superfamily, GSN is a highly structured protein in eukaryotic cells that can be regulated by calcium concentration, intracellular pH, temperature and phosphatidylinositol-4,5-bisphosphate. GSN plays an important role in cellular mechanisms as well as in different cellular interactions. Because of its participation in immunologic processes and its interaction with different cells of the immune system, GSN is a potential candidate for various therapeutic applications. In this review, we summarise the structure of GSN as well as its regulating and functional roles, focusing on distinct diseases such as Alzheimer's disease, rheumatoid arthritis and cancer. A short overview of GSN as a therapeutic target in today's medicine is also provided.
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Pemberton JG, Balla T. Polyphosphoinositide-Binding Domains: Insights from Peripheral Membrane and Lipid-Transfer Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1111:77-137. [PMID: 30483964 DOI: 10.1007/5584_2018_288] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Within eukaryotic cells, biochemical reactions need to be organized on the surface of membrane compartments that use distinct lipid constituents to dynamically modulate the functions of integral proteins or influence the selective recruitment of peripheral membrane effectors. As a result of these complex interactions, a variety of human pathologies can be traced back to improper communication between proteins and membrane surfaces; either due to mutations that directly alter protein structure or as a result of changes in membrane lipid composition. Among the known structural lipids found in cellular membranes, phosphatidylinositol (PtdIns) is unique in that it also serves as the membrane-anchored precursor of low-abundance regulatory lipids, the polyphosphoinositides (PPIn), which have restricted distributions within specific subcellular compartments. The ability of PPIn lipids to function as signaling platforms relies on both non-specific electrostatic interactions and the selective stereospecific recognition of PPIn headgroups by specialized protein folds. In this chapter, we will attempt to summarize the structural diversity of modular PPIn-interacting domains that facilitate the reversible recruitment and conformational regulation of peripheral membrane proteins. Outside of protein folds capable of capturing PPIn headgroups at the membrane interface, recent studies detailing the selective binding and bilayer extraction of PPIn species by unique functional domains within specific families of lipid-transfer proteins will also be highlighted. Overall, this overview will help to outline the fundamental physiochemical mechanisms that facilitate localized interactions between PPIn lipids and the wide-variety of PPIn-binding proteins that are essential for the coordinate regulation of cellular metabolism and membrane dynamics.
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Affiliation(s)
- Joshua G Pemberton
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Tamas Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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Kaplan HM, Şingirik E, Erdoğan KE, Doran F. Protective effect of alpha-linolenic acid on gentamicin-induced ototoxicity in mice. Somatosens Mot Res 2017; 34:145-150. [DOI: 10.1080/08990220.2017.1356283] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Halil Mahir Kaplan
- Department of Pharmacology, Faculty of Medicine, Cukurova University, Adana, Turkey
| | - Ergin Şingirik
- Department of Pharmacology, Faculty of Medicine, Cukurova University, Adana, Turkey
| | | | - Figen Doran
- Department of Pathology, Faculty of Medicine, Cukurova University, Adana, Turkey
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Morikis VA, Radecke C, Jiang Y, Heinrich V, Curry FR, Simon SI. Atrial natriuretic peptide down-regulates neutrophil recruitment on inflamed endothelium by reducing cell deformability and resistance to detachment force. Biorheology 2016; 52:447-63. [PMID: 26639357 DOI: 10.3233/bir-15067] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND Recombinant atrial natriuretic peptide (ANP) is administered in patients with acute heart failure in Japan to improve renal function and hemodynamics, but its anti-inflammatory effect on activated leukocytes may also contribute to its therapeutic efficacy. OBJECTIVE Examine unconventional role of ANP in neutrophil adhesion to inflamed endothelium. METHODS Human neutrophils were perfused over endothelial monolayers in a microfluidic lab-chip assay. Cell rheology was assessed by micropipette aspiration to assess changes in cortical tension and viscosity. Fluorescence microscopy was applied to measure adhesive contact area and β2-integrin focal bond formation. RESULTS ANP inhibited neutrophil rolling and firm adhesion without influencing the upregulation of cellular adhesion molecules on endothelium or the regulation of high affinity CD18 and shedding of L-selectin during neutrophil activation. Exposed to fluid shear, integrin mediated arrest was disrupted with ANP treatment, which elicited formation of long tethers and diminished cell spreading and contact. This correlated with a ∼40% increase in neutrophil viscosity and a reduction in the adhesive footprint. CONCLUSIONS A decrease in cell deformation and neutrophil flattening with ANP results in fewer integrin bond clusters, which translates to higher tensile forces and impaired adhesion strengthening and cell detachment.
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Affiliation(s)
- Vasilios A Morikis
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
| | - Chris Radecke
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
| | - Yanyan Jiang
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
| | - Volkmar Heinrich
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
| | - Fitz-Roy Curry
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA.,Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA 95616, USA
| | - Scott I Simon
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
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Fettucciari K, Ponsini P, Palumbo C, Rosati E, Mannucci R, Bianchini R, Modesti A, Marconi P. Macrophage induced gelsolin in response to Group BStreptococcus(GBS) infection. Cell Microbiol 2014; 17:79-104. [DOI: 10.1111/cmi.12338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 07/04/2014] [Accepted: 07/31/2014] [Indexed: 12/20/2022]
Affiliation(s)
- Katia Fettucciari
- Department of Experimental Medicine; Perugia University; Perugia Italy
| | - Pamela Ponsini
- Department of Experimental Medicine; Perugia University; Perugia Italy
| | - Camilla Palumbo
- Department of Clinical Sciences and Translational Medicine; Tor Vergata University; Rome Italy
| | - Emanuela Rosati
- Department of Experimental Medicine; Perugia University; Perugia Italy
| | - Roberta Mannucci
- Department of Medicine, Laboratory of Image Analysis; Perugia University; Perugia Italy
| | - Rodolfo Bianchini
- Research Program for Receptor Biochemistry and Tumor Metabolism; Laura Bassi Centre of Expertise Therapep; Salzburg University Clinic; Salzburg Austria
- Department of Pediatrics; Paracelsus Medical University; Muellner Hauptstrasse Salzburg Austria
| | - Andrea Modesti
- Department of Clinical Sciences and Translational Medicine; Tor Vergata University; Rome Italy
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Mittal M, Siddiqui MR, Tran K, Reddy SP, Malik AB. Reactive oxygen species in inflammation and tissue injury. Antioxid Redox Signal 2014; 20:1126-67. [PMID: 23991888 PMCID: PMC3929010 DOI: 10.1089/ars.2012.5149] [Citation(s) in RCA: 2714] [Impact Index Per Article: 271.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Abstract Reactive oxygen species (ROS) are key signaling molecules that play an important role in the progression of inflammatory disorders. An enhanced ROS generation by polymorphonuclear neutrophils (PMNs) at the site of inflammation causes endothelial dysfunction and tissue injury. The vascular endothelium plays an important role in passage of macromolecules and inflammatory cells from the blood to tissue. Under the inflammatory conditions, oxidative stress produced by PMNs leads to the opening of inter-endothelial junctions and promotes the migration of inflammatory cells across the endothelial barrier. The migrated inflammatory cells not only help in the clearance of pathogens and foreign particles but also lead to tissue injury. The current review compiles the past and current research in the area of inflammation with particular emphasis on oxidative stress-mediated signaling mechanisms that are involved in inflammation and tissue injury.
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Affiliation(s)
- Manish Mittal
- 1 Department of Pharmacology, Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, Illinois
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Ambriz-Peña X, García-Zepeda EA, Meza I, Soldevila G. Jak3 enables chemokine-dependent actin cytoskeleton reorganization by regulating cofilin and Rac/Rhoa GTPases activation. PLoS One 2014; 9:e88014. [PMID: 24498424 PMCID: PMC3912156 DOI: 10.1371/journal.pone.0088014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 01/03/2014] [Indexed: 01/02/2023] Open
Abstract
We have previously shown that Jak3 is involved in the signaling pathways of CCR7, CCR9 and CXCR4 in murine T lymphocytes and that Jak3−/− lymphocytes display an intrinsic defect in homing to peripheral lymph nodes. However, the molecular mechanism underlying the defective migration observed in Jak3−/− lymphocytes remains elusive. Here, it is demonstrated for the first time, that Jak3 is required for the actin cytoskeleton reorganization in T lymphocytes responding to chemokines. It was found that Jak3 regulates actin polymerization by controlling cofilin inactivation in response to CCL21 and CXCL12. Interestingly, cofilin inactivation was not precluded in PTX- treated cells despite their impaired actin polymerization. Additionally, Jak3 was required for small GTPases Rac1 and RhoA activation, which are indispensable for acquisition of the migratory cell phenotype and the generation of a functional leading edge and uropod, respectively. This defect correlates with data obtained by time-lapse video-microscopy showing an incompetent uropod formation and impaired motility in Jak3-pharmacologically inhibited T lymphocytes. Our data support a new model in which Jak3 and heterotrimeric G proteins can use independent, but complementary, signaling pathways to regulate actin cytoskeleton dynamics during cell migration in response to chemokines.
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Affiliation(s)
- Xochitl Ambriz-Peña
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, Distrito Federal, México
| | - Eduardo Alberto García-Zepeda
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, Distrito Federal, México
| | - Isaura Meza
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados (CINVESTAV IPN), Departamento de Biomedicina Molecular, México, Distrito Federal, México
| | - Gloria Soldevila
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, Distrito Federal, México
- * E-mail:
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NADPH oxidases regulate septin-mediated cytoskeletal remodeling during plant infection by the rice blast fungus. Proc Natl Acad Sci U S A 2013; 110:3179-84. [PMID: 23382235 DOI: 10.1073/pnas.1217470110] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The rice blast fungus Magnaporthe oryzae infects plants with a specialized cell called an appressorium, which uses turgor to drive a rigid penetration peg through the rice leaf cuticle. Here, we show that NADPH oxidases (Nox) are necessary for septin-mediated reorientation of the F-actin cytoskeleton to facilitate cuticle rupture and plant cell invasion. We report that the Nox2-NoxR complex spatially organizes a heteroligomeric septin ring at the appressorium pore, required for assembly of a toroidal F-actin network at the point of penetration peg emergence. Maintenance of the cortical F-actin network during plant infection independently requires Nox1, a second NADPH oxidase, which is necessary for penetration hypha elongation. Organization of F-actin in appressoria is disrupted by application of antioxidants, whereas latrunculin-mediated depolymerization of appressorial F-actin is competitively inhibited by reactive oxygen species, providing evidence that regulated synthesis of reactive oxygen species by fungal NADPH oxidases directly controls septin and F-actin dynamics.
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Penzes P, Cahill ME. Deconstructing signal transduction pathways that regulate the actin cytoskeleton in dendritic spines. Cytoskeleton (Hoboken) 2012; 69:426-41. [PMID: 22307832 DOI: 10.1002/cm.21015] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 01/29/2012] [Accepted: 01/30/2012] [Indexed: 11/10/2022]
Abstract
Dendritic spines are the sites of most excitatory synapses in the central nervous system. Recent studies have shown that spines function independently of each other, and they are currently the smallest known processing units in the brain. Spines exist in an array of morphologies, and spine structure helps dictate synaptic function. Dendritic spines are rich in actin, and actin rearrangements are critical regulators of spine morphology and density. In this review, we discuss the importance of actin in regulating dendritic spine morphogenesis, and discuss the upstream signal transduction pathways that either foster or inhibit actin polymerization. The understanding of actin regulatory pathways is best conceptualized as a hierarchical network in which molecules function in discrete levels defined by their molecular distance to actin. To this end, we focus on several classes of molecules, including guanine nucleotide exchange factors, small GTPases, small GTPase effectors, and actin binding proteins. We discuss how individual proteins in these molecular classes impact spine morphogenesis, and reveal the biochemical interactions in these networks that are responsible for shaping actin polymerization. Finally, we discuss the importance of these actin regulatory pathways in neuropsychiatric disorders.
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Affiliation(s)
- Peter Penzes
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
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Thom SR, Bhopale VM, Yang M, Bogush M, Huang S, Milovanova TN. Neutrophil beta2 integrin inhibition by enhanced interactions of vasodilator-stimulated phosphoprotein with S-nitrosylated actin. J Biol Chem 2011; 286:32854-65. [PMID: 21795685 DOI: 10.1074/jbc.m111.255778] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Production of reactive species in neutrophils exposed to hyperoxia causes S-nitrosylation of β-actin, which increases formation of short actin filaments, leading to alterations in the cytoskeletal network that inhibit β(2) integrin-dependent adherence (Thom, S. R., Bhopale, V. M., Mancini, D. J., and Milovanova, T. N. (2008) J. Biol. Chem. 283, 10822-10834). In this study, we found that vasodilator-stimulated protein (VASP) exhibits high affinity for S-nitrosylated short filamentous actin, which increases actin polymerization. VASP bundles Rac1, Rac2, cyclic AMP-dependent, and cyclic GMP-dependent protein kinases in close proximity to short actin filaments, and subsequent Rac activation increases actin free barbed end formation. Using specific chemical inhibitors or reducing cell concentrations of any of these proteins with small inhibitory RNA abrogates enhanced free barbed end formation, increased actin polymerization, and β(2) integrin inhibition by hyperoxia. Alternatively, incubating neutrophils with formylmethionylleucylphenylalanine or 8-bromo-cyclic GMP activates either cyclic AMP-dependent or cyclic GMP-dependent protein kinase, respectively, outside of the short F-actin pool and phosphorylates VASP on serine 153. Phosphorylated VASP abrogates the augmented polymerization normally observed with S-nitrosylated actin, VASP binding to actin, elevated Rac activity, and elevated formation of actin free barbed ends, thus restoring normal β(2) integrin function.
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Affiliation(s)
- Stephen R Thom
- Institute for Environmental Medicine, Department of Emergency Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA.
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15
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van der Hoeven D, Gizewski ET, Auchampach JA. Activation of the A(3) adenosine receptor inhibits fMLP-induced Rac activation in mouse bone marrow neutrophils. Biochem Pharmacol 2010; 79:1667-73. [PMID: 20149782 DOI: 10.1016/j.bcp.2010.02.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 02/01/2010] [Accepted: 02/02/2010] [Indexed: 01/03/2023]
Abstract
Adenosine is released from injured or hypoxic tissues where it exerts numerous anti-inflammatory effects including suppression of neutrophil functions. Although most previous work has implicated the A(2A)AR, we have recently shown that selective activation of the abundantly expressed A(3)AR inhibits neutrophil superoxide production and chemotaxis providing a potential mechanistic explanation for the efficacy of A(3)AR agonists in experimental animal models of inflammation. In this study, we hypothesized that the A(3)AR suppresses neutrophil functions by inhibiting the monomeric GTPase Rac, a central regulator of chemokine-directed neutrophil migration and superoxide production. We found that pre-treating neutrophils with the highly selective A(3)AR agonist CP-532,903 reduced fMLP-induced Rac activation using an ELISA-based assay that detects all three Rac isoforms. CP-532,903 also inhibited fMLP-induced F-actin formation, a downstream effector function of Rac relevant to neutrophil migration, but not activation of ERK1/2 or p38. Pre-treating neutrophils with CP-532,903 did not stimulate cAMP production or alter fMLP-induced calcium transients, implicating that A(3)AR stimulation does not inhibit Rac activation or neutrophil activities by suppressing Ca(2+) signaling, elevating the intracellular concentration of cAMP, or by cross-desensitizing fMLP receptors. Our results suggest that activation of the A(3)AR signals to suppress neutrophil functions by interfering with the monomeric GTPase Rac, thus contributing to the ant-inflammatory actions of adenosine.
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Affiliation(s)
- Dharini van der Hoeven
- Department of Pharmacology and Toxicology and the Cardiovascular Center, Medical College of Wisconsin, Milwaukee, 53226, United States
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Abstract
Glucose-stimulated insulin secretion from the islet beta-cell involves a sequence of metabolic events and an interplay between a wide range of signaling pathways leading to the generation of second messengers (e.g., cyclic nucleotides, adenine and guanine nucleotides, soluble lipid messengers) and mobilization of calcium ions. Consequent to the generation of necessary signals, the insulin-laden secretory granules are transported from distal sites to the plasma membrane for fusion and release of their cargo into the circulation. The secretory granule transport underlies precise changes in cytoskeletal architecture involving a well-coordinated cross-talk between various signaling proteins, including small molecular mass GTP-binding proteins (G proteins) and their respective effector proteins. The purpose of this article is to provide an overview of current understanding of the identity of small G proteins (e.g., Cdc42, Rac1, and ARF-6) and their corresponding regulatory factors (e.g., GDP/GTP-exchange factors, GDP-dissociation inhibitors) in the pancreatic beta-cell. Plausible mechanisms underlying regulation of these signaling proteins by insulin secretagogues are also discussed. In addition to their positive modulatory roles, certain small G proteins also contribute to the metabolic dysfunction and demise of the islet beta-cell seen in in vitro and in vivo models of impaired insulin secretion and diabetes. Emerging evidence also suggests significant insulin secretory abnormalities in small G protein knockout animals, further emphasizing vital roles for these proteins in normal health and function of the islet beta-cell. Potential significance of these experimental observations from multiple laboratories and possible avenues for future research in this area of islet research are highlighted.
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Affiliation(s)
- Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, 259 Mack Avenue, Detroit, MI 48202-3489, USA.
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17
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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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18
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Rendon BE, Roger T, Teneng I, Zhao M, Al-Abed Y, Calandra T, Mitchell RA. Regulation of human lung adenocarcinoma cell migration and invasion by macrophage migration inhibitory factor. J Biol Chem 2007; 282:29910-8. [PMID: 17709373 DOI: 10.1074/jbc.m704898200] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Macrophage migration inhibitory factor (MIF) is expressed and secreted in response to mitogens and integrin-dependent cell adhesion. Once released, autocrine MIF promotes the activation of RhoA GTPase leading to cell cycle progression in rodent fibroblasts. We now report that small interfering RNA-mediated knockdown of MIF and MIF small molecule antagonism results in a greater than 90% loss of both the migratory and invasive potential of human lung adenocarcinoma cells. Correlating with these phenotypes is a substantial reduction in steady state as well as serum-induced effector binding activity of the Rho GTPase family member, Rac1, in MIF-deficient cells. Conversely, MIF overexpression by adenovirus in human lung adenocarcinoma cells induces a dramatic enhancement of cell migration, and co-expression of a dominant interfering mutant of Rac1 (Rac1(N17)) completely abrogates this effect. Finally, our results indicate that MIF depletion results in defective partitioning of Rac1 to caveolin-containing membrane microdomains, raising the possibility that MIF promotes Rac1 activity and subsequent tumor cell motility through lipid raft stabilization.
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Affiliation(s)
- Beatriz E Rendon
- Molecular Targets Program, J. G. Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202, USA
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19
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El Sayegh TY, Kapus A, McCulloch CA. Beyond the epithelium: Cadherin function in fibrous connective tissues. FEBS Lett 2007; 581:167-74. [PMID: 17217950 DOI: 10.1016/j.febslet.2006.12.029] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Revised: 12/04/2006] [Accepted: 12/12/2006] [Indexed: 11/18/2022]
Abstract
In fibrous connective tissues, fibroblasts are organized into syncytia, cellular networks that enable matrix remodeling and that are interconnected by intercellular adherens junctions (AJs). The AJs of fibroblasts are mediated by N-cadherin, a broadly expressed classical cadherin that is critically involved in developmental processes, wound healing and several diseases of mesenchymal tissues. In contrast to E-cadherin-dependent junctions of epithelia, the formation of AJs in fibrous connective tissues is relatively uncharacterized. Work over the last several years has documented an expanding list of molecules which function to regulate N-cadherin mediated junctions such as: Fer, PTP1B, cortactin, calcium, gelsolin, PIP5KIgamma, PIP2, and the Rho family of GTPases. We present an overview on the regulation of N-cadherin-mediated junction formation that highlights recent molecular advances in the field and rationalizes the roles of N-cadherin in connective tissue function.
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Affiliation(s)
- T Y El Sayegh
- CIHR Group in Matrix Dynamics, University of Toronto, Room 243, Fitzgerald Building, 150 College Street, Toronto, Ont., Canada M5S 3E2.
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20
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Abstract
Gelsolin is a calcium-activated actin filament severing and capping protein found in many cell types and as a secreted form in the plasma of vertebrates. Mutant mice for gelsolin as well as clinical studies have shown that gelsolin is linked to a number of pathological conditions such as inflammation, cancer and amyloidosis. The tight regulation of gelsolin by calcium is crucial for its physiological role and constitutive activation leads to apoptosis. In the following we will give an overview on how gelsolin is regulated by calcium, and which clinical conditions have been linked to lack or misregulation of gelsolin.
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Affiliation(s)
- L Spinardi
- Direzione Scientifica, IRCCS Fondazione Ospedale Policlinico, Mangiagalli e Regina Elena, Via Francesco Sforza 28, 20122 Milano, Italy.
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21
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Ono S. Mechanism of depolymerization and severing of actin filaments and its significance in cytoskeletal dynamics. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 258:1-82. [PMID: 17338919 DOI: 10.1016/s0074-7696(07)58001-0] [Citation(s) in RCA: 212] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The actin cytoskeleton is one of the major structural components of the cell. It often undergoes rapid reorganization and plays crucial roles in a number of dynamic cellular processes, including cell migration, cytokinesis, membrane trafficking, and morphogenesis. Actin monomers are polymerized into filaments under physiological conditions, but spontaneous depolymerization is too slow to maintain the fast actin filament dynamics observed in vivo. Gelsolin, actin-depolymerizing factor (ADF)/cofilin, and several other actin-severing/depolymerizing proteins can enhance disassembly of actin filaments and promote reorganization of the actin cytoskeleton. This review presents advances as well as a historical overview of studies on the biochemical activities and cellular functions of actin-severing/depolymerizing proteins.
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Affiliation(s)
- Shoichiro Ono
- Department of Pathology, Emory University, Atlanta, GA 30322, USA
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22
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Tomas A, Yermen B, Min L, Pessin JE, Halban PA. Regulation of pancreatic beta-cell insulin secretion by actin cytoskeleton remodelling: role of gelsolin and cooperation with the MAPK signalling pathway. J Cell Sci 2006; 119:2156-67. [PMID: 16638805 DOI: 10.1242/jcs.02942] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have previously isolated two MIN6 beta-cell sublines, B1, highly responsive to glucose-stimulated insulin secretion, and C3, markedly refractory (Lilla, V., Webb, G., Rickenbach, K., Maturana, A., Steiner, D. F., Halban, P. A. and Irminger, J. C. (2003) Endocrinology 144, 1368-1379). We now demonstrate that C3 cells have substantially increased amounts of F-actin stress fibres whereas B1 cells have shorter cortical F-actin. Consistent with these data, B1 cells display glucose-dependent actin remodelling whereas, in C3 cells, F-actin is refractory to this secretagogue. Furthermore, F-actin depolymerisation with latrunculin B restores glucose-stimulated insulin secretion in C3 cells. In parallel, glucose-stimulated ERK1/2 activation is greater in B1 than in C3 cells, and is potentiated in both sublines following F-actin depolymerisation. Glucose-activated phosphoERK1/2 accumulates at actin filament tips adjacent to the plasma membrane, indicating that these are the main sites of action for this kinase during insulin secretion. In addition, B1 cell expression of the calcium-dependent F-actin severing protein gelsolin is >100-fold higher than that of C3 cells. Knock-down of gelsolin reduced glucose-stimulated insulin secretion, whereas gelsolin over-expression potentiated secretion from B1 cells. Gelsolin localised along depolymerised actin fibres after glucose stimulation. Taken together, these data demonstrate that F-actin reorganization prior to insulin secretion requires gelsolin and plays a role in the glucose-dependent MAPK signal transduction that regulates beta-cell insulin secretion.
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Affiliation(s)
- Alejandra Tomas
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland.
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23
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Dong JH, Ying GX, Liu X, Wang WY, Wang Y, Ni ZM, Zhou CF. Lesion-induced gelsolin upregulation in the hippocampus following entorhinal deafferentation. Hippocampus 2006; 16:91-100. [PMID: 16261560 DOI: 10.1002/hipo.20134] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Gelsolin is an actin-binding protein that regulates actin filament-severing and capping activity in the various processes of cell motilities. Here, we report the expression of gelsolin mRNA and protein in the hippocampus following transections of the entorhinal afferents. Northern blot analysis showed that transcript of gelsolin was upregulated in a transient manner in the deafferented hippocampus by 1.3-, 2.1-, 1.7-, and 1.1- folds of controls, respectively, at 1, 3, 7, and 15 days postlesion (dpl). In situ hybridization and immunohistochemistry confirmed the temporal expression of gelsolin specifically in the entorhinally denervated zones: the stratum lacunosum-molecular (SLM) of the hippocampus and the outer molecular layer (OML) of the dentate gyrus (DG), which initiated as early as at 1 dpl, reached the maximum at 3 dpl, remained prominently elevated by 7 dpl, and discernibly higher at 15 dpl than that of controls. Double labeling of either gelsolin mRNA or protein with markers of glial cells (Griffonia simplicifolia IB4 and CD11b for microglial cells, GFAP for astroglial cells) revealed that gelsolin was highly expressed by both activated microglia and astrocytes. The results suggest that the spatiotemporal upregulation of gelsolin in the hippocampus is induced by entorhinal deafferentation, and that gelsolin would participate in the activation processes of both microglial and astroglial cells and thereby, indirectly play important roles in the subsequent lesion-induced neural reorganization in the hippocampus following entorhinal deafferentation.
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Affiliation(s)
- Jing-Hui Dong
- Key Laboratory of Neurobiology, Shanghai Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, People's Republic of China
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24
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Abstract
The migration of endothelial cells (ECs) plays an important role in vascular remodeling and regeneration. EC migration can be regulated by different mechanisms such as chemotaxis, haptotaxis, and mechanotaxis. This review will focus on fluid shear stress-induced mechanotransduction during EC migration. EC migration and mechanotransduction can be modulated by cytoskeleton, cell surface receptors such as integrins and proteoglycans, the chemical and physical properties of extracellular matrix (ECM) and cell-cell adhesions. The shear stress applied on the luminal surface of ECs can be sensed by cell membrane and associated receptor and transmitted throughout the cell to cell-ECM adhesions and cell-cell adhesions. As a result, shear stress induces directional migration of ECs by promoting lamellipodial protrusion and the formation of focal adhesions (FAs) at the front in the flow direction and the disassembly of FAs at the rear. Persistent EC migration in the flow direction can be driven by polarized activation of signaling molecules and the positive feedback loops constituted by Rho GTPases, cytoskeleton, and FAs at the leading edge. Furthermore, shear stress-induced EC migration can overcome the haptotaxis of ECs. Given the hemodynamic environment of the vascular system, mechanotransduction during EC migration has a significant impact on vascular development, angiogenesis, and vascular wound healing.
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Affiliation(s)
- Song Li
- Department of Bioengineering and Center for Functional Tissue Engineering, University of California-Berkeley, San Francisco/Berkeley, California 94720, USA.
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25
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Abstract
Phagocytosis is the mechanism of internalization used by specialized cells such as macrophages, dendritic cells, and neutrophils to internalize, degrade, and eventually present peptides derived from particulate antigens. The phagocytic process comprises several sequential and complex events initiated by the recognition ofligands on the surface of the particles by specific receptors on the surface of the phagocytic cells. Receptor clustering at the attachment site generates a phagocytic signal that in turn leads to local polymerization of actin filaments and to particle internalization. Depending on the particles and receptors involved, it appears that the structures and mechanisms associated with particle ingestion are diverse. However, work during the past few years has highlighted the importance of small GTP-binding proteins of the Rho family in various types of phagocytosis. As reviewed here, Rho family GTPases, their activators, and their downstream effectors control the local reorganization of the actin cytoskeleton beneath bound particles.
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Affiliation(s)
- F Niedergang
- Membrane and Cytoskeleton Dynamics Group, Institut Curie, CNRS UMR144, 75248 Paris, France
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26
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Abstract
Cell motility is an essential cellular process for a variety of biological events. The process of cell migration requires the integration and coordination of complex biochemical and biomechanical signals. The protrusion force at the leading edge of a cell is generated by the cytoskeleton, and this force generation is controlled by multiple signaling cascades. The formation of new adhesions at the front and the release of adhesions at the rear involve the outside-in and inside-out signaling mediated by integrins and other adhesion receptors. The traction force generated by the cell on the extracellular matrix (ECM) regulates cell-ECM adhesions, and the counter force exerted by ECM on the cell drives the migration. The polarity of cell migration can be amplified and maintained by the feedback loop between the cytoskeleton and cell-ECM adhesions. Cell migration in three-dimensional ECM has characteristics distinct from that on two-dimensional ECM. The migration of cells is initiated and modulated by external chemical and mechanical factors, such as chemoattractants and the mechanical forces acting on the cells and ECM, as well as the surface density, distribution, topography, and rigidity of the ECM.
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Affiliation(s)
- Song Li
- Department of Bioengineering and Center for Tissue Engineering, University of California, Berkeley, CA 94720, USA
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27
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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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28
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Mi S, Lee X, Shao Z, Thill G, Ji B, Relton J, Levesque M, Allaire N, Perrin S, Sands B, Crowell T, Cate RL, McCoy JM, Pepinsky RB. LINGO-1 is a component of the Nogo-66 receptor/p75 signaling complex. Nat Neurosci 2004; 7:221-8. [PMID: 14966521 DOI: 10.1038/nn1188] [Citation(s) in RCA: 622] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2003] [Accepted: 12/24/2003] [Indexed: 02/02/2023]
Abstract
Axon regeneration in the adult CNS is prevented by inhibitors in myelin. These inhibitors seem to modulate RhoA activity by binding to a receptor complex comprising a ligand-binding subunit (the Nogo-66 receptor NgR1) and a signal transducing subunit (the neurotrophin receptor p75). However, in reconstituted non-neuronal systems, NgR1 and p75 together are unable to activate RhoA, suggesting that additional components of the receptor may exist. Here we describe LINGO-1, a nervous system-specific transmembrane protein that binds NgR1 and p75 and that is an additional functional component of the NgR1/p75 signaling complex. In non-neuronal cells, coexpression of human NgR1, p75 and LINGO-1 conferred responsiveness to oligodendrocyte myelin glycoprotein, as measured by RhoA activation. A dominant-negative human LINGO-1 construct attenuated myelin inhibition in transfected primary neuronal cultures. This effect on neurons was mimicked using an exogenously added human LINGO-1-Fc fusion protein. Together these observations suggest that LINGO-1 has an important role in CNS biology.
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MESH Headings
- Amino Acid Sequence/genetics
- Animals
- Animals, Newborn
- Astrocytes/metabolism
- Axons/metabolism
- Base Sequence/genetics
- Cells, Cultured
- DNA, Complementary/analysis
- DNA, Complementary/genetics
- Fetus
- GPI-Linked Proteins
- Humans
- Macromolecular Substances
- Membrane Proteins/genetics
- Membrane Proteins/isolation & purification
- Membrane Proteins/metabolism
- Molecular Sequence Data
- Mutation/genetics
- Myelin Proteins/metabolism
- Myelin Sheath/metabolism
- Myelin-Associated Glycoprotein/genetics
- Myelin-Associated Glycoprotein/isolation & purification
- Myelin-Associated Glycoprotein/metabolism
- Myelin-Oligodendrocyte Glycoprotein
- Nerve Regeneration/physiology
- Nerve Tissue Proteins
- Nogo Receptor 1
- Protein Structure, Tertiary/genetics
- Rats
- Receptor, Nerve Growth Factor
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/isolation & purification
- Receptors, Cell Surface/metabolism
- Receptors, Nerve Growth Factor/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Signal Transduction/genetics
- rhoA GTP-Binding Protein/metabolism
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Affiliation(s)
- Sha Mi
- Department of Discovery Biology, Biogen Idec, Inc., 14 Cambridge Center, Cambridge, Massachusetts 02142, USA.
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29
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Zhang S, Murphy TH. Ca 2+ -independent spine dynamics in cultured hippocampal neurons. Mol Cell Neurosci 2004; 25:334-44. [PMID: 15019949 DOI: 10.1016/j.mcn.2003.10.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2003] [Revised: 09/02/2003] [Accepted: 10/21/2003] [Indexed: 11/24/2022] Open
Abstract
Developing spines are highly dynamic processes that undergo rapid morphologic changes. We have investigated whether basal developmentally regulated spine motility is triggered by spontaneous changes in intracellular Ca(2+) ([Ca(2+)](i)). To address the link between Ca(2+) transients and motility, we have used the cell-permeable chelator BAPTA-AM. Consistent with others, we found that young cultured hippocampal neurons [7-13 days in vitro (DIV)] display significantly more spine motility than older neurons (14-21 days in vitro). Control experiments indicate that BAPTA-AM can lower basal [Ca(2+)](i) as well as block synaptically mediated Ca(2+) transients. However, globally buffering [Ca(2+)](i) by BAPTA-AM treatment failed to significantly alter the basal motility of developing spines measured at either relatively slow (5 min) or faster sampling times (every 20 s). We conclude that the basal spine motility of cultured hippocampal neurons may represent an intrinsic feature of developing neurons and is not necessarily choreographed by ongoing changes in [Ca(2+)](i) levels.
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Affiliation(s)
- Shengxiang Zhang
- Kinsmen Laboratory of Nuerology Research and Brain Research Centre, University of British Columbia, Vancouver, Columbia, Canada
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30
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Arora PD, Glogauer M, Kapus A, Kwiatkowski DJ, McCulloch CA. Gelsolin mediates collagen phagocytosis through a rac-dependent step. Mol Biol Cell 2003; 15:588-99. [PMID: 14617805 PMCID: PMC329256 DOI: 10.1091/mbc.e03-07-0468] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The role of gelsolin, a calcium-dependent actin-severing protein, in mediating collagen phagocytosis, is not defined. We examined alpha 2 beta 1 integrin-mediated phagocytosis in fibroblasts from wild-type (WT) and gelsolin knockout (Gsn(-)) mice. After initial contact with collagen beads, collagen binding and internalization were 60% lower in Gsn(-) than WT cells. This deficiency was restored by transfection with gelsolin or with beta1 integrin-activating antibodies. WT cells showed robust rac activation and increased [Ca(2+)](i) during early contact with collagen beads, but Gsn(-) cells showed very limited responses. Transfected gelsolin in Gsn(-) cells restored rac activation after collagen binding. Transfection of Gsn(-) cells with active rac increased collagen binding to WT levels. Chelation of intracellular calcium inhibited collagen binding and rac activation, whereas calcium ionophore induced rac activation in WT and Gsn(-) cells. We conclude that the ability of gelsolin to remodel actin filaments is important for collagen-induced calcium entry; calcium in turn is required for rac activation, which subsequently enhances collagen binding to unoccupied alpha 2 beta 1 integrins.
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Affiliation(s)
- Pamela D Arora
- Canadian Institutes of Health Research Group in Matrix Dynamics, University of Toronto, Toronto, Ontario, Canada M5S 3E2
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31
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Dettin M, Bicciato S, Scarinci C, Cline E, Lingen MW, Di Bello C. Synthetic Peptides Derived from the Angiostatin K4 Domain Inhibit Endothelial Cell Migration. Chembiochem 2003; 4:1238-42. [PMID: 14613119 DOI: 10.1002/cbic.200300711] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Monica Dettin
- Department of Chemical Process Engineering, University of Padua, 35131 Padua, Italy.
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32
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Abstract
The monomeric GTPase Rac and the lipid kinase phosphoinositide 3-kinase (PI3K) are intracellular signalling enzymes that each regulate a huge range of cellular functions. Their signalling pathways overlap. Several pathways lead from PI3K activation via the production of the lipid second messenger phosphatidylinositol (3,4,5)-triphosphate (PtdIns(3,4,5)P(3)) to the activation of guanine-nucleotide exchange factors (GEFs) that activate Rac. Vice versa, Rac can also stimulate the activation of PI3K, although the mechanism for this is unclear. We review here the evidence that links PI3K and Rac signalling pathways.
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Affiliation(s)
- Heidi C E Welch
- Inositide Laboratory, Signalling Programme, The Babraham Institute, Cambridge CB2 4AT, UK.
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33
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Dib K, Melander F, Axelsson L, Dagher MC, Aspenström P, Andersson T. Down-regulation of Rac activity during beta 2 integrin-mediated adhesion of human neutrophils. J Biol Chem 2003; 278:24181-8. [PMID: 12676940 DOI: 10.1074/jbc.m302300200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In human neutrophils, beta2 integrin engagement mediated a decrease in GTP-bound Rac1 and Rac2. Pretreatment of neutrophils with LY294002 or PP1 (inhibiting phosphatidylinositol 3-kinase (PI 3-kinase) and Src kinases, respectively) partly reversed the beta2 integrin-induced down-regulation of Rac activities. In contrast, beta2 integrins induced stimulation of Cdc42 that was independent of Src family members. The PI 3-kinase dependence of the beta2 integrin-mediated decrease in GTP-bound Rac could be explained by an enhanced Rac-GAP activity, since this activity was blocked by LY204002, whereas PP1 only had a minor effect. The fact that only Rac1 but not Rac2 (the dominating Rac) redistributed to the detergent-insoluble fraction and that it was independent of GTP loading excludes the possibility that down-regulation of Rac activities was due to depletion of GTP-bound Rac from the detergent-soluble fraction. The beta2 integrin-triggered relocalization of Rac1 to the cytoskeleton was enabled by a PI 3-kinase-induced dissociation of Rac1 from LyGDI. The dissociations of Rac1 and Rac2 from LyGDI also explained the PI 3-kinase-dependent translocations of Rac GTPases to the plasma membrane. However, these accumulations of Rac in the membrane, as well as that of p47phox and p67phox, were also regulated by Src tyrosine kinases. Inasmuch as Rac GTPases are part of the NADPH oxidase and the respiratory burst is elicited in neutrophils adherent by beta2 integrins, our results indicate that activation of the NADPH oxidase does not depend on the levels of Rac-GTP but instead requires a beta2 integrin-induced targeting of the Rac GTPases as well as p47phox and p67phox to the plasma membrane.
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Affiliation(s)
- Karim Dib
- Department of Laboratory Medicine, Lund University, Malmö University Hospital, Entrance 78, SE-205 02 Malmö, Sweden.
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34
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Tardif M, Brouchon L, Rabiet MJ, Boulay F. Direct binding of a fragment of the Wiskott-Aldrich syndrome protein to the C-terminal end of the anaphylatoxin C5a receptor. Biochem J 2003; 372:453-63. [PMID: 12600272 PMCID: PMC1223397 DOI: 10.1042/bj20021803] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2002] [Revised: 02/20/2003] [Accepted: 02/25/2003] [Indexed: 11/17/2022]
Abstract
Migration of myeloid cells towards a source of chemoattractant, such as the C5a anaphylatoxin, is triggered by the activation of a G-protein-coupled receptor. In the present study, we have used a yeast two-hybrid approach to find unknown partners of the C5a receptor (C5aR). Using the cytosolic C-terminal region of C5aR as bait to screen a human leucocyte cDNA library, we identified the Wiskott-Aldrich syndrome protein (WASP) as a potential partner of C5aR. WASP is known to have an essential function in regulating actin dynamics at the cell leading edge. The interaction was detected with both the fragment of WASP containing amino acids 1-321 (WASP.321) and WASP with its actin-nucleation-promoting domain [verprolin-like, central and acidic (VCA) domain] deleted. The interaction between C5aR and the WASP.321 was supported further by an in vitro binding assay between a radiolabelled WASP.321 fragment and a receptor C-terminus glutathione S-transferase (GST) fusion protein, as well as by GST pull-down, co-immunoprecipitation and immunofluorescence experiments. In the yeast two-hybrid assay, full-length WASP showed no ability to interact with the C-terminal domain of C5aR. This is most probably due to an auto-inhibited conformation imposed by the VCA domain. In HEK-293T cells co-transfected with full-length WASP and C5aR, only a small amount of WASP was co-precipitated with the receptor. However, in the presence of the active form of the GTPase Cdc42 (Cdc42V12), which is thought to switch WASP to an active 'open conformation', the amount of WASP associated with the receptor was markedly increased. We hypothesize that a transient interaction between C5aR and WASP occurs following the stimulation of C5aR and Cdc42 activation. This might be one mechanism by which WASP is targeted to the plasma membrane and by which actin assembly is spatially controlled in cells moving in a gradient of C5a.
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Affiliation(s)
- Marianne Tardif
- Laboratoire de Biochimie et Biophysique des Systèmes Intégrés, Commissariat à l'Energie Atomique (CEA)/Centre National de la Recherche Scientifique (CNRS)/Université Joseph Fourier, CEA-Grenoble, France.
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35
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Yuan XB, Jin M, Xu X, Song YQ, Wu CP, Poo MM, Duan S. Signalling and crosstalk of Rho GTPases in mediating axon guidance. Nat Cell Biol 2003; 5:38-45. [PMID: 12510192 DOI: 10.1038/ncb895] [Citation(s) in RCA: 228] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2002] [Revised: 07/02/2002] [Accepted: 11/15/2002] [Indexed: 11/08/2022]
Abstract
Axon extension during development of the nervous system is guided by many factors, but the signalling mechanisms responsible for triggering this extension remain mostly unknown. Here we have examined the role of Rho family small guanosine triphosphatases (GTPases) in mediating axon guidance by diffusible factors. Expression of either dominant-negative or constitutively active Cdc42 in cultured Xenopus laevis spinal neurons, at a concentration that does not substantially affect filopodial formation and neurite extension, abolishes the chemoattractive growth cone turning induced by a gradient of brain-derived neurotrophic factor that can activate Cdc42 and Rac in cultured neurons. Chemorepulsion induced by a gradient of lysophosphatidic acid is also abolished by the expression of dominant-negative RhoA. We also show that an asymmetry in Rho kinase or filopodial initiation across the growth cone is sufficient to trigger the turning response and that there is a crosstalk between the Cdc42 and RhoA pathways through their converging actions on the myosin activity essential for growth cone chemorepulsion.
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Affiliation(s)
- Xiao-bing Yuan
- Institute of Neuroscience, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, 320 Yue-yang Road, Shanghai 200031, China
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36
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Cicchetti G, Allen PG, Glogauer M. Chemotactic signaling pathways in neutrophils: from receptor to actin assembly. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 2002; 13:220-8. [PMID: 12090462 DOI: 10.1177/154411130201300302] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In this review, we present an overview of the signaling elements between neutrophil chemotactic receptors and the actin cytoskeleton that drives cell motility. From receptor-ligand interactions, activation of heterotrimeric G-proteins, their downstream effectors PLC and PI-3 kinase, the activation of small GTPases of the Rho family, and their regulation of particular cytoskeletal regulatory proteins, we describe pathways specific to the chemotaxing neutrophil and elements documented to be important for neutrophil function.
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Affiliation(s)
- Gregor Cicchetti
- Hematology Division, Harvard Medical School, Brigham and Women's Hospital, LMRC 301, Boston, MA 02115, USA
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37
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Werner E, Werb Z. Integrins engage mitochondrial function for signal transduction by a mechanism dependent on Rho GTPases. J Cell Biol 2002; 158:357-68. [PMID: 12119354 PMCID: PMC2173123 DOI: 10.1083/jcb.200111028] [Citation(s) in RCA: 207] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We show here the transient activation of the small GTPase Rac, followed by a rise in reactive oxygen species (ROS), as necessary early steps in a signal transduction cascade that lead to NFkappaB activation and collagenase-1 (CL-1)/matrix metalloproteinase-1 production after integrin-mediated cell shape changes. We show evidence indicating that this constitutes a new mechanism for ROS production mediated by small GTPases. Activated RhoA also induced ROS production and up-regulated CL-1 expression. A Rac mutant (L37) that prevents reorganization of the actin cytoskeleton prevented integrin-induced CL-1 expression, whereas mutations that abrogate Rac binding to the neutrophil NADPH membrane oxidase in vitro (H26 and N130) did not. Instead, ROS were produced by integrin-induced changes in mitochondrial function, which were inhibited by Bcl-2 and involved transient membrane potential loss. The cells showing this transient decrease in mitochondrial membrane potential were already committed to CL-1 expression. These results unveil a new molecular mechanism of signal transduction triggered by integrin engagement where a global mitochondrial metabolic response leads to gene expression rather than apoptosis.
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Affiliation(s)
- Erica Werner
- Department of Anatomy, University of California, San Francisco, CA 94143.
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38
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Dong Y, Asch HL, Ying A, Asch BB. Molecular mechanism of transcriptional repression of gelsolin in human breast cancer cells. Exp Cell Res 2002; 276:328-36. [PMID: 12027462 DOI: 10.1006/excr.2002.5534] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Loss of gelsolin, a tumor suppressor, is one of the most frequently occurring molecular defects in breast cancers of diverse etiologies and across at least three animal species: human, mouse, and rat. Our previous analysis of breast cancer cells demonstrated that the deficiency is not due to mutation of the gelsolin gene, but instead to epigenetic factors, including decreased transcription of the gene. The study described herein provides the first functional characterization of the human gelsolin promoter and reveals a mechanistic basis for the reduced gelsolin transcription. In reporter gene assays, the gelsolin promoter was less active in low-gelsolin-expressing breast cancer cells. A cis-element mediating this reduced promoter activity was defined as a 27-bp sequence located approximately 135 bp upstream of the transcription start site. Gel shift and supershift assays and Southwestern blotting analysis indicated that activating transcription factor-1 (ATF-1) and a protein of approximately 100 kDa may have cancer cell-specific DNA-binding activity to the 27-bp gelsolin cis-element. Although the ATF-1 protein was highly expressed in both benign and tumorigenic breast cells, its DNA-binding activity was selectively abundant in the cancer cells and correlated inversely with the gelsolin mRNA level. Thus, our results suggest a role for ATF-1 in gelsolin promoter silencing in contrast to its transactivating effect on various other promoters.
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Affiliation(s)
- Yan Dong
- Division of Experimental Pathology, Roswell Park Cancer Institute (RPCI), Buffalo, New York 14263, USA
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39
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Welch HCE, Coadwell WJ, Ellson CD, Ferguson GJ, Andrews SR, Erdjument-Bromage H, Tempst P, Hawkins PT, Stephens LR. P-Rex1, a PtdIns(3,4,5)P3- and Gbetagamma-regulated guanine-nucleotide exchange factor for Rac. Cell 2002; 108:809-21. [PMID: 11955434 DOI: 10.1016/s0092-8674(02)00663-3] [Citation(s) in RCA: 419] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rac, a member of the Rho family of monomeric GTPases, is an integrator of intracellular signaling in a wide range of cellular processes. We have purified a PtdIns(3,4,5)P3-sensitive activator of Rac from neutrophil cytosol. It is an abundant, 185 kDa guanine-nucleotide exchange factor (GEF), which we cloned and named P-Rex1. The recombinant enzyme has Rac-GEF activity that is directly, substantially, and synergistically activated by PtdIns(3,4,5)P3 and Gbetagammas both in vitro and in vivo. P-Rex1 antisense oligonucleotides reduced endogenous P-Rex1 expression and C5a-stimulated reactive oxygen species formation in a neutrophil-like cell line. P-Rex1 appears to be a coincidence detector in PtdIns(3,4,5)P3 and Gbetagamma signaling pathways that is particularly adapted to function downstream of heterotrimeric G proteins in neutrophils.
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40
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Star EN, Kwiatkowski DJ, Murthy VN. Rapid turnover of actin in dendritic spines and its regulation by activity. Nat Neurosci 2002; 5:239-46. [PMID: 11850630 DOI: 10.1038/nn811] [Citation(s) in RCA: 353] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dendritic spines are motile structures that contain high concentrations of filamentous actin. Using hippocampal neurons expressing fluorescent actin and the method of fluorescence recovery after photobleaching, we found that 85 +/- 2% of actin in the spine was dynamic, with a turnover time of 44.2 +/- 4.0 s. The rapid turnover is not compatible with current models invoking a large population of stable filaments and static coupling of filaments to postsynaptic components. Low-frequency stimulation known to induce long-term depression in these neurons stabilized nearly half the dynamic actin in the spine. This effect depended on the activation of N-methyl-D-aspartate (NMDA) receptors and the influx of calcium. In neurons from mice lacking gelsolin, a calcium-dependent actin-binding protein, activity-dependent stabilization of actin was impaired. Our studies provide new information on the kinetics of actin turnover in spines, its regulation by neural activity and the mechanisms involved in this regulation.
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Affiliation(s)
- Erin N Star
- Department of Molecular & Cellular Biology, Harvard University, 16 Divinity Ave., Cambridge, Massachusetts 02138, USA
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41
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Lewis A, Di Ciano C, Rotstein OD, Kapus A. Osmotic stress activates Rac and Cdc42 in neutrophils: role in hypertonicity-induced actin polymerization. Am J Physiol Cell Physiol 2002; 282:C271-9. [PMID: 11788338 DOI: 10.1152/ajpcell.00427.2001] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypertonicity inhibits a variety of neutrophil functions through poorly defined mechanisms. Our earlier studies suggest that osmotically induced actin polymerization and cytoskeleton remodeling is a key component in the hypertonic block of exocytosis and cell movement. To gain insight into the signaling mechanisms underlying the hyperosmotic F-actin response, we investigated whether hypertonicity stimulates Rac and Cdc42 and, if so, whether their activation contributes to the hypertonic rise in F-actin. Using a recently developed pull-down assay that specifically captures the active forms of these small GTPases, we found that hypertonicity caused an ~2.5- and ~7.2-fold activation of Rac and Cdc42, respectively. This response was rapid and sustained. Small GTPase activation was not mediated by the osmotic stimulation of Src kinases, heterotrimeric G proteins, or phosphatidylinositol 3-kinase. Interestingly, an increase in intracellular ionic strength was sufficient to activate Rac even in the absence of cell shrinkage. Inhibition of Rac and Cdc42 by Clostridium difficile toxin B substantially reduced but did not abolish the hypertonicity-induced F-actin response. Thus hypertonicity is a potent activator of Rac and Cdc42, and this effect seems to play an important but not exclusive role in the hyperosmolarity-triggered cytoskeleton remodeling.
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Affiliation(s)
- Alison Lewis
- Department of Surgery, The Toronto General Hospital University Health Network, and University of Toronto, Toronto, Ontario, Canada
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42
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Lange K. Role of microvillar cell surfaces in the regulation of glucose uptake and organization of energy metabolism. Am J Physiol Cell Physiol 2002; 282:C1-26. [PMID: 11742794 DOI: 10.1152/ajpcell.2002.282.1.c1] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Experimental evidence suggesting a type of glucose uptake regulation prevailing in resting and differentiated cells was surveyed. This type of regulation is characterized by transport-limited glucose metabolism and depends on segregation of glucose transporters on microvilli of differentiated or resting cells. Earlier studies on glucose transport regulation and a recently presented general concept of influx regulation for ions and metabolic substrates via microvillar structures provide the basic framework for this theory. According to this concept, glucose uptake via transporters on microvilli is regulated by changes in the structural organization of the microfilament bundle, which is acting as a diffusion barrier between the microvillar tip compartment and the cytoplasm. Both microvilli formation and the switch of glucose metabolism from "metabolic regulation" to "transport limitation" occur during differentiation. The formation of microvillar cell surfaces creates the essential preconditions to establish the characteristic functions of specialized tissue cells including the coordination between glycolysis and oxidative phosphorylation, regulation of cellular functions by external signals, and Ca(2+) signaling. The proposed concept integrates various aspects of glucose uptake regulation into a ubiquitous cellular mechanism involved in regulation of transmembrane ion and substrate fluxes.
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43
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Abstract
Bacteria, apoptotic cells and other particulate material are taken up through phagocytosis, a conserved cellular function driven by actin polymerization. As reviewed here, small GTPases of the Rho family, their activators and effectors control the local reorganization of the actin cytoskeleton underneath bound particles. Remarkably, the molecular actors and regulatory mechanisms involved during phagocytosis through the FcR or the CR3 receptors are very similar to those underlying the cytoskeletal rearrangements that take place at the leading edge of motile cell and at adhesion sites, respectively.
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Affiliation(s)
- F Castellano
- Laboratoire de la Dynamique de la Membrane et du Cytosquelette, Centre National de la Recherche Scientifique UMR144, Institut Curie, 26 rue d'Ulm, 75241 Paris Cedex 5, France
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44
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Friedl P, Borgmann S, Bröcker E. Amoeboid leukocyte crawling through extracellular matrix: lessons from the
Dictyostelium
paradigm of cell movement. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.4.491] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Peter Friedl
- Cell Migration Laboratory, Department of Dermatology, University of Würzburg, Würzburg, Germany
| | - Stefan Borgmann
- Cell Migration Laboratory, Department of Dermatology, University of Würzburg, Würzburg, Germany
| | - Eva‐B. Bröcker
- Cell Migration Laboratory, Department of Dermatology, University of Würzburg, Würzburg, Germany
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45
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Zunino R, Li Q, Rosé SD, Romero-Benítez MM, Lejen T, Brandan NC, Trifaró JM. Expression of scinderin in megakaryoblastic leukemia cells induces differentiation, maturation, and apoptosis with release of plateletlike particles and inhibits proliferation and tumorigenesis. Blood 2001; 98:2210-9. [PMID: 11568009 DOI: 10.1182/blood.v98.7.2210] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rapid proliferation of atypical megakaryoblasts is a characteristic of megakaryoblastic leukemia. Cells from patients with this disorder and cell lines established from this type of leukemia showed the presence of gelsolin but the absence of scinderin expression, 2 filamentous actin-severing proteins present in normal megakaryocytes and platelets. Vector-mediated expression of scinderin in the megakaryoblastic cell line MEG-01 induced a decrease in both F-actin and gelsolin. This was accompanied by increased Rac2 expression and by activation of the PAK/MEKK.SEK/JNK/c-jun, c-fos transduction pathway. The Raf/MEK/ERK pathway was also activated in these cells. Transduction pathway activation was followed by cell differentiation, polyploidization, maturation, and apoptosis with release of platelet-like particles. Particles expressed surface CD41a antigen (glycoprotein IIb/IIIa or fibrinogen receptor), had dense bodies, high-affinity serotonin transport, and circular array of microtubules. Treatment of particles with thrombin induced serotonin release and aggregation that was blocked by CD41a antibodies. PAC-1 antibodies also blocked aggregation. Exposure of cells to PD98059, a blocker of MEK, inhibited antigen CD41a expression, increases in cell volume, and number of protoplasmic extensions. Cell proliferation and cell ability to form tumors in nude mice were also inhibited by the expression of scinderin. MEG-01 cells expressing scinderin had the same fate in vivo as in culture. Thus, when injected into nude mice, they entered apoptosis and released platelet-like particles. The lack of scinderin expression in megakaryoblastic leukemia cells seems to be responsible for their inability to enter into differentiation and maturation pathways characteristic of their normal counterparts.
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Affiliation(s)
- R Zunino
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ontario, Canada
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46
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Worthylake RA, Burridge K. Leukocyte transendothelial migration: orchestrating the underlying molecular machinery. Curr Opin Cell Biol 2001; 13:569-77. [PMID: 11544025 DOI: 10.1016/s0955-0674(00)00253-2] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Transendothelial migration of leukocytes involves the spatiotemporal regulation of adhesion molecules, chemokines and cytoskeletal regulators. Recent results show that distinct steps of leukocyte transendothelial migration are regulated by sequential integrin activation and coordinated Rho family GTPase activity. Progress has been made in understanding how the dynamic regulation of these molecules translates into leukocyte transmigration.
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Affiliation(s)
- R A Worthylake
- Department of Cell and Developmental Biology, CB #7090, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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47
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Abstract
Gelsolin is activated by Ca(2+) to sever actin filaments. Ca(2+) regulation is conferred on the N-terminal half by the C-terminal half. This paper seeks to understand how Ca(2+) regulates gelsolin by testing the "tail helix latch hypothesis," which is based on the structural data showing that gelsolin has a C-terminal tail helix that contacts the N-terminal half in the absence of Ca(2+). Ca(2+) activation of gelsolin at 37 degrees C occurs in three steps, with apparent K(d) for Ca(2+) of 0.1, 0.3, and 6.4 x 10(-6) m. Tail helix truncation decreases the apparent Ca(2+) requirement for severing to 10(-7) m and eliminates the conformational change observed at 10(-6) m Ca(2+). The large decrease in Ca(2+) requirement for severing is not due to a change in Ca(2+) binding nor to Ca(2+)-independent activation of the C-terminal half per se. Thus, the tail helix latch is primarily responsible for transmitting micromolar Ca(2+) information from the gelsolin C-terminal half to the N-terminal half. Occupation of submicromolar Ca(2+)-binding sites primes gelsolin for severing, but gelsolin cannot sever because the tail latch is still engaged. Unlatching the tail helix by 10(-6) m Ca(2+) releases the final constraint to initiate the severing cascade.
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Affiliation(s)
- K M Lin
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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48
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Serrander L, Skarman P, Rasmussen B, Witke W, Lew DP, Krause KH, Stendahl O, Nüsse O. Selective inhibition of IgG-mediated phagocytosis in gelsolin-deficient murine neutrophils. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:2451-7. [PMID: 10946270 DOI: 10.4049/jimmunol.165.5.2451] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phagocytosis and the microbicidal functions of neutrophils require dynamic changes of the actin cytoskeleton. We have investigated the role of gelsolin, a calcium-dependent actin severing and capping protein, in peripheral blood neutrophils from gelsolin-null (Gsn-) mice. The phagocytosis of complement opsonized yeast was only minimally affected. In contrast, phagocytosis of IgG-opsonized yeast was reduced close to background level in Gsn- neutrophils. Thus, gelsolin is essential for efficient IgG- but not complement-mediated phagocytosis. Furthermore, attachment of IgG-opsonized yeast to Gsn- neutrophils was reduced ( approximately 50%) but not to the same extent as ingestion ( approximately 73%). This was not due to reduced surface expression of the Fcgamma-receptor or its lateral mobility. This suggests that attachment and ingestion of IgG-opsonized yeast by murine neutrophils are actin-dependent and gelsolin is important for both steps in phagocytosis. We also investigated granule exocytosis and several steps in phagosome processing, namely the formation of actin around the phagosome, translocation of granules, and activation of the NADPH-oxidase. All these functions were normal in Gsn- neutrophils. Thus, the role of gelsolin is specific for IgG-mediated phagocytosis. Our data suggest that gelsolin is part of the molecular machinery that distinguishes complement and IgG-mediated phagocytosis. The latter requires a more dynamic reorganization of the cytoskeleton.
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Affiliation(s)
- L Serrander
- Divison of Infectious Diseases, University of Geneva, Switzerland.
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49
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Glogauer M, Hartwig J, Stossel T. Two pathways through Cdc42 couple the N-formyl receptor to actin nucleation in permeabilized human neutrophils. J Cell Biol 2000; 150:785-96. [PMID: 10953003 PMCID: PMC2175292 DOI: 10.1083/jcb.150.4.785] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2000] [Accepted: 06/23/2000] [Indexed: 12/03/2022] Open
Abstract
We developed a permeabilization method that retains coupling between N-formyl-methionyl-leucyl-phenylalanine tripeptide (FMLP) receptor stimulation, shape changes, and barbed-end actin nucleation in human neutrophils. Using GTP analogues, phosphoinositides, a phosphoinositide-binding peptide, constitutively active or inactive Rho GTPase mutants, and activating or inhibitory peptides derived from neural Wiskott-Aldrich syndrome family proteins (N-WASP), we identified signaling pathways leading from the FMLP receptor to actin nucleation that require Cdc42, but then diverge. One branch traverses the actin nucleation pathway involving N-WASP and the Arp2/3 complex, whereas the other operates through active Rac to promote actin nucleation. Both pathways depend on phosphoinositide expression. Since maximal inhibition of the Arp2/3 pathway leaves an N17Rac inhibitable alternate pathway intact, we conclude that this alternate involves phosphoinositide-mediated uncapping of actin filament barbed ends.
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Affiliation(s)
- M Glogauer
- Hematology Division, Brigham and Women's Hospital, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA.
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50
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Funatsu N, Kumanogoh H, Sokawa Y, Maekawa S. Identification of gelsolin as an actin regulatory component in a triton insoluble low density fraction (raft) of newborn bovine brain. Neurosci Res 2000; 36:311-7. [PMID: 10771109 DOI: 10.1016/s0168-0102(99)00125-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A membrane microdomain enriched in cholesterol and glycosphingolipids, or so called 'raft' region, was found to contain many signal transducing proteins such as GPI-anchored cell adhesion molecules, trimeric G proteins, and protein tyrosine kinases. In previous studies, we showed that the raft region obtained from rat brain contains two cytoskeletal proteins, tubulin and actin, as the major components in addition to these signal transducing proteins. In this study, to know the biochemical mechanisms regulating the cytoskeletal organization in this region, actin regulatory activities in raft were surveyed. We found the presence of a Ca(2+)-dependent actin nucleation promoting activity in raft. The solubilization and column fractionation of this activity combined with western blotting and immunoprecipitation showed that gelsolin is one of the actin regulatory proteins in raft.
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Affiliation(s)
- N Funatsu
- Department of Biotechnology, Faculty of Textile Science, Kyoto Institute of Technology, Kyoto, Japan
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