151
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Manetti F. LIM kinases are attractive targets with many macromolecular partners and only a few small molecule regulators. Med Res Rev 2011; 32:968-98. [PMID: 22886629 DOI: 10.1002/med.20230] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The LIM kinases 1 and 2 (LIMK1 and LIMK2) are dual specificity (serine/threonine and tyrosine) kinases. Although they show significant structural similarity, LIMK1 and LIMK2 show different expression, subcellular localization, and functions. They are involved in many cellular functions, such as migration, cycle, and neuronal differentiation and also have a role in pathological processes, such as cancer cell invasion and metastatis, as well as in neurodevelopmental disorders (namely, the William's syndrome). LIM kinases have a relevant number of known partners that are able to induce or limit the ability of LIMK1 and LIMK2 to phosphorylate and inactivate their major substrate, cofilin. On the contrary, only a limited number of small molecules that interact with the two proteins to modulate their kinase activity have been identified. In this review, the most important partners of LIM kinases and their modulating activity toward LIMKs are described. The small compounds identified as LIMK1 and LIMK2 modulators are also reported, as well as their role as possible therapeutic agents for LIMK-induced diseases.
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Affiliation(s)
- Fabrizio Manetti
- Dipartimento Farmaco Chimico Tecnologico, Università degli Studi di Siena, via Alcide de Gasperi 2, I-53100 Siena, Italy.
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152
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Marsick BM, Flynn KC, Santiago-Medina M, Bamburg JR, Letourneau PC. Activation of ADF/cofilin mediates attractive growth cone turning toward nerve growth factor and netrin-1. Dev Neurobiol 2010; 70:565-88. [PMID: 20506164 DOI: 10.1002/dneu.20800] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Proper neural circuitry requires that growth cones, motile tips of extending axons, respond to molecular guidance cues expressed in the developing organism. However, it is unclear how guidance cues modify the cytoskeleton to guide growth cone pathfinding. Here, we show acute treatment with two attractive guidance cues, nerve growth factor (NGF) and netrin-1, for embryonic dorsal root ganglion and temporal retinal neurons, respectively, results in increased growth cone membrane protrusion, actin polymerization, and filamentous actin (F-actin). ADF/cofilin (AC) family proteins facilitate F-actin dynamics, and we found the inactive phosphorylated form of AC is decreased in NGF- or netrin-1-treated growth cones. Directly increasing AC activity mimics addition of NGF or netrin-1 to increase growth cone protrusion and F-actin levels. Extracellular gradients of NGF, netrin-1, and a cell-permeable AC elicit attractive growth cone turning and increased F-actin barbed ends, F-actin accumulation, and active AC in growth cone regions proximal to the gradient source. Reducing AC activity blunts turning responses to NGF and netrin. Our results suggest that gradients of NGF and netrin-1 locally activate AC to promote actin polymerization and subsequent growth cone turning toward the side containing higher AC activity.
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Affiliation(s)
- Bonnie M Marsick
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, USA
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153
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Kim JE, Ryu HJ, Kim MJ, Kim DW, Kwon OS, Choi SY, Kang TC. Pyridoxal-5′-phosphate phosphatase/chronophin induces astroglial apoptosis via actin-depolymerizing factor/cofilin system in the rat brain following status epilepticus. Glia 2010; 58:1937-48. [DOI: 10.1002/glia.21063] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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154
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Oleinik NV, Krupenko NI, Krupenko SA. ALDH1L1 inhibits cell motility via dephosphorylation of cofilin by PP1 and PP2A. Oncogene 2010; 29:6233-44. [PMID: 20729910 PMCID: PMC2992098 DOI: 10.1038/onc.2010.356] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Here we report that ALDH1L1 (FDH, a folate enzyme with tumor suppressor-like properties) inhibits cell motility. The underlying mechanism involves F-actin stabilization, re-distribution of cytoplasmic actin towards strong preponderance of filamentous actin, and formation of actin stress fibers. A549 cells expressing FDH demonstrated a much slower recovery of GFP-actin fluorescence in a FRAP assay, as well as an increase in G-actin polymerization and a decrease in F-actin depolymerization rates in pyren-actin fluorescence assays indicating the inhibition of actin dynamics. These effects were associated with robust dephosphorylation of the actin depolymerizing factor cofilin by PP1 and PP2A serine/threonine protein phosphatases but not the cofilin-specific phosphatases slingshot and chronophin. In fact, the PP1/PP2A inhibitor calyculin prevented cofilin dephosphorylation and restored motility. Inhibition of FDH-induced apoptosis by the JNK inhibitor SP600125 or the pan-caspase inhibitor zVAD-fmk did not restore motility or levels of phospho-cofilin, indicating that the observed effects are independent from FDH function in apoptosis. Interestingly, cofilin siRNA or expression of phosphorylation-deficient S3A cofilin mutant resulted in a decrease of G-actin and the actin stress fiber formation, the effects seen upon FDH expression. In contrast, the expression of S3D mutant, mimicking constitutive phosphorylation, prevented these effects further supporting the cofilin-dependent mechanism. Dephosphorylation of cofilin and inhibition of motility in response to FDH can be also prevented by the increased folate in media. Furthermore, folate depletion itself, in the absence of FDH, resulted in cofilin dephosphorylation and inhibition of motility in several cell lines. Our experiments showed that these effects were folate-specific and not a general response to nutrient starvation. Overall, this study demonstrates the presence of distinct intracellular signaling pathways regulating motility in response to folate status and points toward mechanisms involving folates in promoting a malignant phenotype.
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Affiliation(s)
- N V Oleinik
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
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155
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Abstract
The cellular and molecular mechanisms orchestrating the complex process by which bone marrow megakaryocytes form and release platelets remain poorly understood. Mature megakaryocytes generate long cytoplasmic extensions, proplatelets, which have the capacity to generate platelets. Although microtubules are the main structural component of proplatelets and microtubule sliding is known to drive proplatelet elongation, the role of actin dynamics in the process of platelet formation has remained elusive. Here, we tailored a mouse model lacking all ADF/n-cofilin-mediated actin dynamics in megakaryocytes to specifically elucidate the role of actin filament turnover in platelet formation. We demonstrate, for the first time, that in vivo actin filament turnover plays a critical role in the late stages of platelet formation from megakaryocytes and the proper sizing of platelets in the periphery. Our results provide the genetic proof that platelet production from megakaryocytes strictly requires dynamic changes in the actin cytoskeleton.
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156
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Davis RC, Maloney MT, Minamide LS, Flynn KC, Stonebraker MA, Bamburg JR. Mapping cofilin-actin rods in stressed hippocampal slices and the role of cdc42 in amyloid-beta-induced rods. J Alzheimers Dis 2010; 18:35-50. [PMID: 19542631 DOI: 10.3233/jad-2009-1122] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Dissociated hippocampal neurons exposed to a variety of degenerative stimuli form neuritic cofilin-actin rods. Here we report on stimulus driven regional rod formation in organotypic hippocampal slices. Ultrastructural analysis of rods formed in slices demonstrates mitochondria and vesicles become entrapped within some rods. We developed a template for combining and mapping data from multiple slices, enabling statistical analysis for the identification of vulnerable sub-regions. Amyloid-beta (Abeta) induces rods predominantly in the dentate gyrus region, and Abeta-induced rods are reversible following washout. Rods that persist 24 h following transient (30 min) ATP-depletion are broadly distributed, whereas rods formed in response to excitotoxic glutamate localize within and nearby the pyramidal neurons. Time-lapse imaging of cofilin-GFP-expressing neurons within slices shows neuronal rod formation begins rapidly and peaks by 10 min of anoxia. In approximately 50% of responding neurons, Abeta-induced rod formation acts via cdc42, an upstream regulator of cofilin. These new observations support a role for cofilin-actin rods in stress-induced disruption of cargo transport and synaptic function within hippocampal neurons and suggest both cdc42-dependent and independent pathways modulate cofilin activity downstream from Abeta.
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Affiliation(s)
- Richard C Davis
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.,Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, USA
| | - Michael T Maloney
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.,Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - Laurie S Minamide
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Kevin C Flynn
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.,Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, USA.,Max Planck Institute of Neurobiology, Martinsreid, Munich, Germany
| | - Matthew A Stonebraker
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - James R Bamburg
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.,Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, USA
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157
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Zoudilova M, Min J, Richards HL, Carter D, Huang T, DeFea KA. beta-Arrestins scaffold cofilin with chronophin to direct localized actin filament severing and membrane protrusions downstream of protease-activated receptor-2. J Biol Chem 2010; 285:14318-29. [PMID: 20207744 PMCID: PMC2863192 DOI: 10.1074/jbc.m109.055806] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 02/11/2010] [Indexed: 01/17/2023] Open
Abstract
Protease-activated receptor-2 (PAR-2) mediates pro-inflammatory signals in a number of organs, including enhancing leukocyte recruitment to sites of injury and infection. At the cellular level, PAR-2 promotes activation of the actin filament-severing protein cofilin, which is crucial for the reorganization of the actin cytoskeleton and chemotaxis. These responses require the scaffolding functions of beta-arrestins; however, the mechanism by which beta-arrestins spatially regulate cofilin activity and the role of this pathway in primary cells has not been investigated. Here, using size-exclusion chromatography and co-immunoprecipitation, we demonstrate that PAR-2 promotes the formation of a complex containing beta-arrestins, cofilin, and chronophin (CIN) in primary leukocytes and cultured cells. Both association of cofilin with CIN and cell migration are inhibited in leukocytes from beta-arrestin-2(-/-) mice. We show that, in response to PAR-2 activation, beta-arrestins scaffold cofilin with its upstream activator CIN, to facilitate the localized generation of free actin barbed ends, leading to membrane protrusion. These studies suggest that a major role of beta-arrestins in chemotaxis is to spatially regulate cofilin activity to facilitate the formation of a leading edge, and that this pathway may be important for PAR-2-stimulated immune cell migration.
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Affiliation(s)
| | - Jungah Min
- From the Cell, Molecular, and Developmental Biology Program
| | - Heddie L. Richards
- Biomedical Sciences Division, University of California, Riverside, California 92521 and
| | | | - Timothy Huang
- the Department of Immunology, The Scripps Research Institute, La Jolla, California 92037
| | - Kathryn A. DeFea
- From the Cell, Molecular, and Developmental Biology Program
- Biomedical Sciences Division, University of California, Riverside, California 92521 and
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158
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Kim JE, Kim DW, Kwak SE, Ryu HJ, Yeo SI, Kwon OS, Choi SY, Kang TC. Pyridoxal-5'-phosphate phosphatase/chronophin inhibits long-term potentiation induction in the rat dentate gyrus. Hippocampus 2010; 19:1078-89. [PMID: 19253407 DOI: 10.1002/hipo.20568] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pyridoxal-5'-phosphate (PLP)-phosphatase/chronophin (PLPP/CIN) directly dephosphorylates actin-depolymerizing factor (ADF)/cofilin as well as PLP. Although PLPP/CIN plays a role in the regulation of F-actin and vitamin B(6) metabolism, there is no direct evidence to support a correlation between PLPP/CIN and F-actin polymerization during long-term potentiation (LTP) induction. In this study, we investigated whether the expression of PLPP/CIN is altered following LTP induction, and whether Tat-PLPP/CIN transduction affects LTP induction in the rat dentate gyrus (DG). PLPP/CIN immunoreactivity was markedly decreased in dentate granule cells after the induction of LTP. Tat-PLPP/CIN transduction (20 and 200 microg/kg) decreased the efficiency of high frequency stimulus-induced potentiation of populations spike amplitude as compared to saline or Tat-protein-treated animals. The PLPP/CIN protein level showed an inverse correlation with phosphorylated ADF/cofilin levels and F-actin content. These findings suggest that PLPP/CIN-mediated actin dynamics may play an important role in the changes of morphological properties (dendritic spine reorganization) of the hippocampus in LTP.
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Affiliation(s)
- Ji-Eun Kim
- Department of Anatomy and Neurobiology, College of Medicine, Hallym University, Chunchon, Kangwon-Do, South Korea
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159
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Impact of marine drugs on cytoskeleton-mediated reproductive events. Mar Drugs 2010; 8:881-915. [PMID: 20479959 PMCID: PMC2866467 DOI: 10.3390/md8040881] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 03/02/2010] [Accepted: 03/23/2010] [Indexed: 12/30/2022] Open
Abstract
Marine organisms represent an important source of novel bioactive compounds, often showing unique modes of action. Such drugs may be useful tools to study complex processes such as reproduction; which is characterized by many crucial steps that start at gamete maturation and activation and virtually end at the first developmental stages. During these processes cytoskeletal elements such as microfilaments and microtubules play a key-role. In this review we describe: (i) the involvement of such structures in both cellular and in vitro processes; (ii) the toxins that target the cytoskeletal elements and dynamics; (iii) the main steps of reproduction and the marine drugs that interfere with these cytoskeleton-mediated processes. We show that marine drugs, acting on microfilaments and microtubules, exert a wide range of impacts on reproductive events including sperm maturation and motility, oocyte maturation, fertilization, and early embryo development.
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160
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Wickramarachchi DC, Theofilopoulos AN, Kono DH. Immune pathology associated with altered actin cytoskeleton regulation. Autoimmunity 2010; 43:64-75. [PMID: 20001423 DOI: 10.3109/08916930903374634] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The actin cytoskeleton plays a crucial role in a variety of important cellular processes required for normal immune function, including locomotion, intercellular interactions, endocytosis, cytokinesis, signal transduction, and maintenance of cell morphology. Recent studies have uncovered not only many of the components and mechanisms that regulate the cortical actin cytoskeleton but have also revealed significant immunopathological consequences associated with genetic alteration of actin cytoskeletal regulatory genes. These advances have provided new insights into the role of cortical actin cytoskeletal regulation in a number of immune cell functions and have identified cytoskeletal regulatory proteins critical for normal immune system activity and susceptibility to autoimmunity.
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Affiliation(s)
- Dilki C Wickramarachchi
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA
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161
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Oser M, Condeelis J. The cofilin activity cycle in lamellipodia and invadopodia. J Cell Biochem 2010; 108:1252-62. [PMID: 19862699 DOI: 10.1002/jcb.22372] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The actin severing protein cofilin is essential for directed cell migration and chemotaxis, in many cell types and is also important for tumor cell invasion during metastasis. Through its severing activity, cofilin increases the number of free barbed ends to initiate actin polymerization for actin-based protrusion in two distinct subcellular compartments in invasive tumor cells: lamellipodia and invadopodia. Cofilin severing activity is tightly regulated and multiple mechanisms are utilized to regulate cofilin activity. In this prospect, we have grouped the primary on/off regulation into two broad categories, both of which are important for inhibiting cofilin from binding to F-actin or G-actin: (1) Blocking cofilin activity by the binding of cofilin to either PI(4,5)P(2) at lamellipodia, or cortactin at invadopodia. (2) Blocking cofilin's ability to bind to actin via serine phosphorylation. Although the literature suggests that these cofilin regulatory mechanisms may be cell-type dependent, we propose the existence of a common cofilin activity cycle in which both operate. In this common cycle, the mechanism used to initiate cofilin activity is determined by the starting point in the cycle in a given subcellular compartment.
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Affiliation(s)
- Matthew Oser
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA.
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162
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Abstract
Vascular smooth muscle cell migration is important during vascular development and contributes to lesion formation in the adult vasculature. The mechanisms regulating migration of this cell type are therefore of great interest. Recent work has shown that reactive oxygen species (ROS) derived from NADPH oxidases are important mediators of promigratory signaling pathways. ROS regulate the intracellular signals responsible for lamellipodia formation, actin cytoskeleton remodeling, focal adhesion turnover, and contraction of the cell body. In addition, they contribute to matrix remodeling, a critical step to initiate and support vascular smooth muscle cell motility. Despite these recent advances in our understanding of the redox mechanisms that contribute to migration, additional work is needed to evaluate fully the potential of ROS-sensitive molecular signals as therapeutic targets to prevent inappropriate smooth muscle cell migration.
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163
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Furnish EJ, Brophy CM, Harris VA, Macomson S, Winger J, Head GA, Shaver EG. Treatment with transducible phosphopeptide analogues of the small heat shock–related protein, HSP20, after experimental subarachnoid hemorrhage: prevention and reversal of delayed decreases in cerebral perfusion. J Neurosurg 2010; 112:631-9. [DOI: 10.3171/2009.7.jns09730] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Delayed vasospasm is a significant cause of morbidity and mortality after subarachnoid hemorrhage (SAH). Proteomic therapeutics offers a new modality in which biologically active proteins or peptides are transduced into cells via covalent linkage to cell permeant peptides (CPPs). The hypothesis of this study was that either intrathecal or intravenous delivery of a phosphopeptide mimetic of the small heat shock–related protein, HSP20, linked to a CPP, would inhibit delayed decreases in cerebral perfusion after experimental SAH in a rat model.
Methods
This study was conducted in 3 parts: 1) prevention and 2) reversal of delayed decreases in cerebral perfusion via either intrathecal or intravenous administration of a CPP linked to phosphopeptide mimetics of HSP20 (AZX100) and 3) determining the effect of intravenous administration of AZX100 on blood pressure and heart rate. Subarachnoid hemorrhage was induced in rats by endovascular perforation. Subsequently, AZX100 was administered intrathecally via a cisternal catheter or intravenously. Cerebral perfusion was determined by laser Doppler monitoring. Blood pressure was monitored by telemetry in a separate group of naïve animals treated with AZX100 for 24 hours.
Results
The maximal decrease in cerebral perfusion occurred 3 days after SAH. Cisternal administration of AZX100 (0.14–0.57 mg/kg) 24 hours after hemorrhage prevented decreases in cerebral perfusion after SAH. Animals receiving lower doses of AZX100 (0.068 mg/kg) or a scrambled sequence of the active HSP20 peptide linked to CPP developed decreases in cerebral perfusion similar to those seen in control animals. Intravenous administration of AZX100 (1.22 mg/kg) 24 hours after hemorrhage prevented the decreases in cerebral perfusion seen in the controls. Intravenous administration (0.175 mg/kg and 1.22 mg/kg) of AZX100 on Days 2 and 3 after SAH reversed decreases in cerebral perfusion as early as Day 3. There was no impact of AZX100 on blood pressure or heart rate at doses up to 2.73 mg/kg.
Conclusions
Cisternal administration of AZX100 24 hours after hemorrhage prevented decreases in cerebral perfusion. Intravenous administration of AZX100 also prevented and reversed decreases in cerebral perfusion at doses that did not induce hypotension. Transduction of biologically active motifs of downstream regulators like HSP20 represents a potential novel treatment for SAH.
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Affiliation(s)
| | - Colleen M. Brophy
- 2Vascular Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | | | | | - Julia Winger
- 3Neurosurgery, Augusta Veterans Administration Medical Center
| | - Geoffrey A. Head
- 6Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Ellen G. Shaver
- 3Neurosurgery, Augusta Veterans Administration Medical Center
- 4Departments of Neurosurgery and
- 5Medicine (Institute for Molecular Medicine and Genetics), Medical College of Georgia
- 7Neurological Associates of Augusta, Augusta, Georgia; and
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164
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Abstract
The reversible phosphorylation of proteins is accomplished by opposing activities of kinases and phosphatases. Relatively few protein serine/threonine phosphatases (PSPs) control the specific dephosphorylation of thousands of phosphoprotein substrates. Many PSPs, exemplified by protein phosphatase 1 (PP1) and PP2A, achieve substrate specificity and regulation through combinatorial interactions between conserved catalytic subunits and a large number of regulatory subunits. Other PSPs, represented by PP2C and FCP/SCP, contain both catalytic and regulatory domains within the same polypeptide chain. Here, we discuss biochemical and structural investigations that advance the mechanistic understanding of the three major classes of PSPs, with a focus on PP2A.
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Affiliation(s)
- Yigong Shi
- Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
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165
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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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166
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Abstract
The present study identified the proteins that are differentially expressed during ischemic brain injury. Adult male rats were performed a middle cerebral artery occlusion (MCAO) to induce cerebral ischemia, and brains were collected at 24 hr after MCAO. Protein analysis was performed on the cerebral cortex using two-dimensional gel electrophoresis. Protein spots with a greater than 3 fold change in intensity between the sham and MCAO groups were identified by mass spectrometry. Among these proteins, 60 kDa heat shock protein, dehydropyrimidinase-related protein 2, t-complex protein 1, and Rho GDP dissociation inhibitor levels were significantly increased in MCAO group compared to those of the sham group. In contrast, thioredoxin, peroxiredoxin-2, stathmin, ubiquitin carboxy-terminal hydrolase L1, guanine nucleotide-binding protein alpha, pyridoxal-5'-phosphate phosphatase, and apoplipoprotein A-I levels were significantly decreased in MCAO group. These results suggest that cerebral ischemia induces neuronal cells death by changing expression levels of several proteins.
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Affiliation(s)
- Phil-Ok Koh
- Department of Anatomy, College of Veterinary Medicine and Research Institute of Life Science, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701, South Korea.
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167
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Allen KN, Dunaway-Mariano D. Markers of fitness in a successful enzyme superfamily. Curr Opin Struct Biol 2009; 19:658-65. [PMID: 19889535 DOI: 10.1016/j.sbi.2009.09.008] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 09/25/2009] [Accepted: 09/30/2009] [Indexed: 11/17/2022]
Abstract
Haloalkanoic acid dehalogenase (HAD) superfamily members serve as the predominant catalysts of metabolic phosphate ester hydrolysis in all three superkingdoms of life. Collectively, the known structural, bioinformatic, and mechanistic data offer a glimpse of the variety of HAD enzymes that have evolved in the service of metabolic expansion. Factors that have contributed to superfamily dominance include a chemically versatile nucleophile, stability of the core superfold, structural modularity of the chemistry and specificity domains, conformational coupling conferred by the topology of the inserted specificity elements, and retention of a conserved mold for stabilization of the trigonal bipyramidal transition state.
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Affiliation(s)
- Karen N Allen
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, MA 02215-2521, USA.
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168
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Po'uha ST, Shum MSY, Goebel A, Bernard O, Kavallaris M. LIM-kinase 2, a regulator of actin dynamics, is involved in mitotic spindle integrity and sensitivity to microtubule-destabilizing drugs. Oncogene 2009; 29:597-607. [PMID: 19881550 DOI: 10.1038/onc.2009.367] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
LIM-kinase 2 (LIMK2) belongs to the LIMK family of proteins, which comprises LIMK1 and LIMK2. Both proteins regulate actin polymerization through phosphorylation and inactivation of the actin depolymerizing factor cofilin. In this study, we show that the level of LIMK2 protein is increased in neuroblastoma, BE(2)-C cells, selected for resistance to microtubule-destabilizing agents, vincristine and colchicine. However, the level of phosphorylated LIMK1 and LIMK2 was similar in the resistant and parental BE(2)-C cells. In contrast, the level of phospho-cofilin was greatly increased in the drug-resistant cells. Downregulation of LIMK2 expression increases sensitivity of neuroblastoma SH-EP cells to vincristine and vinblastine but not to microtubule-stabilizing agents, while it's overexpression increased its resistance to vincristine. Its vincristine-induced mitotic arrest was moderately inhibited in the LIMK2 knockdown cells, suggesting that the increased drug sensitivity is through an alternative mechanism other then mitotic arrest and apoptosis. Moreover, downregulation of LIMK2 expression induces formation of abnormal mitotic spindles, an effect enhanced in the presence of microtubule-destabilizing agents. LIMK2 is important for normal mitotic spindle formation and altered LIMK2 expression mediates sensitivity to microtubule destabilizing agents. These findings suggest that inhibition of LIMK2 activity may be used for the treatment of tumors resistant to microtubule-destabilizing drugs.
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Affiliation(s)
- S T Po'uha
- Children's Cancer Institute Australia for Medical Research, Randwick, New South Wales 2031, Australia
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169
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Muscle LIM protein interacts with cofilin 2 and regulates F-actin dynamics in cardiac and skeletal muscle. Mol Cell Biol 2009; 29:6046-58. [PMID: 19752190 DOI: 10.1128/mcb.00654-09] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The muscle LIM protein (MLP) and cofilin 2 (CFL2) are important regulators of striated myocyte function. Mutations in the corresponding genes have been directly associated with severe human cardiac and skeletal myopathies, and aberrant expression patterns have often been observed in affected muscles. Herein, we have investigated whether MLP and CFL2 are involved in common molecular mechanisms, which would promote our understanding of disease pathogenesis. We have shown for the first time, using a range of biochemical and immunohistochemical methods, that MLP binds directly to CFL2 in human cardiac and skeletal muscles. The interaction involves the inter-LIM domain, amino acids 94 to 105, of MLP and the amino-terminal domain, amino acids 1 to 105, of CFL2, which includes part of the actin depolymerization domain. The MLP/CFL2 complex is stronger in moderately acidic (pH 6.8) environments and upon CFL2 phosphorylation, while it is independent of Ca(2+) levels. This interaction has direct implications in actin cytoskeleton dynamics in regulating CFL2-dependent F-actin depolymerization, with maximal depolymerization enhancement at an MLP/CFL2 molecular ratio of 2:1. Deregulation of this interaction by intracellular pH variations, CFL2 phosphorylation, MLP or CFL2 gene mutations, or expression changes, as observed in a range of cardiac and skeletal myopathies, could impair F-actin depolymerization, leading to sarcomere dysfunction and disease.
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170
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Marshall TW, Aloor HL, Bear JE. Coronin 2A regulates a subset of focal-adhesion-turnover events through the cofilin pathway. J Cell Sci 2009; 122:3061-9. [PMID: 19654210 DOI: 10.1242/jcs.051482] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Coronins are conserved F-actin-binding proteins that are important for motility and actin dynamics. Unlike type I coronins, coronin 2A localizes to stress fibers and some focal adhesions, and is excluded from the leading edge. Depletion of coronin 2A in MTLn3 cells decreases cell motility and turnover of focal adhesions. Surprisingly, none of the pathways known to regulate focal-adhesion turnover are affected by depletion of coronin 2A. Depletion of coronin 2A does, however, increase phospho-cofilin, suggesting that misregulation of cofilin might affect adhesion dynamics. Slingshot-1L, a cofilin-activating phosphatase, localizes to focal adhesions and interacts with coronin 2A. Depletion of coronin 2A reduces cofilin activity at focal adhesions, as measured by barbed-end density and actin FRAP. In both fixed cells and live cells, cofilin localizes to the proximal end of some focal adhesions. Although expression of wild-type cofilin in coronin-2A-depleted cells has no major effect on focal-adhesion dynamics, expression of an active mutant of cofilin bypasses the defects in cell motility and focal-adhesion disassembly. These results implicate both coronin 2A and cofilin as factors that can regulate a subset of focal-adhesion-turnover events.
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Affiliation(s)
- Thomas W Marshall
- Lineberger Comprehensive Cancer Center and Department of Cell and Developmental Biology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA
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171
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Bamburg JR, Bloom GS. Cytoskeletal pathologies of Alzheimer disease. CELL MOTILITY AND THE CYTOSKELETON 2009; 66:635-49. [PMID: 19479823 PMCID: PMC2754410 DOI: 10.1002/cm.20388] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The histopathological hallmarks of Alzheimer disease are the extracellular amyloid plaques, composed principally of the amyloid beta peptide, and the intracellular neurofibrillary tangles, composed of paired helical filaments of the microtubule-associated protein, tau. Other histopathological structures involving actin and the actin-binding protein, cofilin, have more recently been recognized. Here we review new findings about these cytoskeletal pathologies, and, emphasize how plaques, tangles, the actin-containing inclusions and their respective building blocks may contribute to Alzheimer pathogenesis and the primary behavioral symptoms of the disease. Cell Motil. Cytoskeleton, 2009. (c) 2009 Wiley-Liss, Inc.
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Affiliation(s)
- James R Bamburg
- Department of Biochemistry and Molecular Biology, Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado, USA.
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172
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Unraveling a novel Rac1-mediated signaling pathway that regulates cofilin dephosphorylation and secretion in thrombin-stimulated platelets. Blood 2009; 114:415-24. [DOI: 10.1182/blood-2008-10-183582] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Abstract
In platelets stimulated by thrombin to secrete and aggregate, cofilin is rapidly dephosphorylated leading to its activation. Cofilin by severing existing actin filaments and stimulating F-actin polymerization on newly created barbed ends dynamizes the actin cytoskeleton. We previously found that cofilin dephosphorylation is Ca2+-dependent and occurs upstream of degranulation in stimulated platelets. We report now in thrombin-stimulated platelets that Rac1 and class II PAKs (PAK4/5/6) were rapidly (within 5 seconds) activated, whereas PAK1/2 (class I PAKs) phosphorylation was slower. The Rac1-specific inhibitor NSC23766 blocked phosphorylation of class II PAKs, but not PAK1/2. Moreover, inhibition of the Ca2+/calmodulin-dependent phosphatase calcineurin inhibited Rac1 activation and class II PAKs phosphorylation. Prevention of Rac1 activation by calcineurin inhibition or NSC23766 also blocked cofilin dephosphorylation and platelet granule secretion indicating that a calcineurin/Rac1/class II PAKs pathway regulates cofilin dephosphorylation leading to secretion. We further found that PI3-kinases were activated downstream of Rac1, but were not involved in regulating cofilin dephosphorylation and secretion in thrombin-stimulated platelets. Our study unravels a Ca2+-dependent pathway of secretion in stimulated platelets as a signaling pathway linking Rac1 activation to actin dynamics: calcineurin→Rac1→class II PAKs→cofilin activation. We further demonstrate that this pathway is separate and independent of the protein kinase C (PKC) pathway mediating secretion.
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173
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Peterburs P, Heering J, Link G, Pfizenmaier K, Olayioye MA, Hausser A. Protein Kinase D Regulates Cell Migration by Direct Phosphorylation of the Cofilin Phosphatase Slingshot 1 Like. Cancer Res 2009; 69:5634-8. [DOI: 10.1158/0008-5472.can-09-0718] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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174
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van Rheenen J, Condeelis J, Glogauer M. A common cofilin activity cycle in invasive tumor cells and inflammatory cells. J Cell Sci 2009; 122:305-11. [PMID: 19158339 DOI: 10.1242/jcs.031146] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In many cell types, the formation of membrane protrusions and directional migration depend on the spatial and temporal regulation of the actin-binding protein cofilin. Cofilin, which is important for the regulation of actin-polymerization initiation, increases the number of actin free barbed ends through three mechanisms: its intrinsic actin-nucleation activity; binding and severing of existing actin filaments; and recycling actin monomers from old filaments to new ones through its actin-depolymerization activity. The increase in free barbed ends that is caused by cofilin initiates new actin polymerization, which can be amplified by the actin-nucleating ARP2/3 complex. Interestingly, different cell systems seem to have different mechanisms of activating cofilin. The initial activation of cofilin in mammary breast tumors is dependent on PLCgamma, whereas cofilin activation in neutrophils is additionally dependent on dephosphorylation, which is promoted through Rac2 signaling. Although the literature seems to be confusing and inconsistent, we propose that all of the data can be explained by a single activity-cycle model. In this Opinion, we give an overview of cofilin activation in both tumor cells and inflammatory cells, and demonstrate how the differences in cofilin activation that are observed in various cell types can be explained by different starting points in this single common activity cycle.
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Affiliation(s)
- Jacco van Rheenen
- Department of Anatomy and Structural Biology, Gruss Lipper Center for Biophotonics, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA.
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175
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Actin microfilaments guide the polarized transport of nuclear pore complexes and the cytoplasmic dispersal of Vasa mRNA during GVBD in the ascidian Halocynthia roretzi. Dev Biol 2009; 330:377-88. [PMID: 19362546 DOI: 10.1016/j.ydbio.2009.04.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 03/30/2009] [Accepted: 04/03/2009] [Indexed: 12/16/2022]
Abstract
Meiosis reinitiation starts with the germinal vesicle breakdown (GVBD) within the gonad before spawning. Here, we have extended our previous observations and identified the formation of conspicuous actin bundles emanating from the germinal vesicle (GV) during its breakdown in the ascidian Halocynthia roretzi. Time-lapse video recordings and fluorescent labelling of microfilaments (MFs) indicate that these microfilamentous structures invariantly elongate towards the vegetal hemisphere at the estimated speed of 20 mum/min. Interestingly, the nuclear pore complex protein Nup153 accumulates at the vegetal tip of actin bundles. To determine if these structures play a role in the formation of the germ plasm, we have analyzed the localization pattern of Vasa transcript in maturing oocytes and early embryos. We found that Hr-Vasa mRNA, one of Type II postplasmic/PEM mRNAs, changes from a granular and perinuclear localization to an apparent uniform cytoplasmic distribution during oocyte maturation, and then concentrate in the centrosome-attracting body (CAB) by the eight-cell stage. In addition, treatments with Latrunculin B, but not with Nocodazole, blocked the redistribution of Nup153 and Hr-Vasa mRNA, suggesting that these mechanisms are both actin-dependant. We discuss the pleiotropic role played by MFs, and the relationship between nuclear pores, maternal Vasa mRNA and germ plasm in maturing ascidian oocytes.
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176
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Krishnan N, Jeong DG, Jung SK, Ryu SE, Xiao A, Allis CD, Kim SJ, Tonks NK. Dephosphorylation of the C-terminal tyrosyl residue of the DNA damage-related histone H2A.X is mediated by the protein phosphatase eyes absent. J Biol Chem 2009; 284:16066-16070. [PMID: 19351884 DOI: 10.1074/jbc.c900032200] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
In mammalian cells, the DNA damage-related histone H2A variant H2A.X is characterized by a C-terminal tyrosyl residue, Tyr-142, which is phosphorylated by an atypical kinase, WSTF. The phosphorylation status of Tyr-142 in H2A.X has been shown to be an important regulator of the DNA damage response by controlling the formation of gammaH2A.X foci, which are platforms for recruiting molecules involved in DNA damage repair and signaling. In this work, we present evidence to support the identification of the Eyes Absent (EYA) phosphatases, protein-tyrosine phosphatases of the haloacid dehalogenase superfamily, as being responsible for dephosphorylating the C-terminal tyrosyl residue of histone H2A.X. We demonstrate that EYA2 and EYA3 displayed specificity for Tyr-142 of H2A.X in assays in vitro. Suppression of eya3 by RNA interference resulted in elevated basal phosphorylation and inhibited DNA damage-induced dephosphorylation of Tyr-142 of H2A.X in vivo. This study provides the first indication of a physiological substrate for the EYA phosphatases and suggests a novel role for these enzymes in regulation of the DNA damage response.
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Affiliation(s)
- Navasona Krishnan
- From the Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724
| | - Dae Gwin Jeong
- Medical Proteomics Research Center, Korea Research Institute of Bioscience and Biotechnology, 52 Eoeun-Dong, Yuseong-Gu, Daejeon 305-333, Korea
| | - Suk-Kyeong Jung
- Medical Proteomics Research Center, Korea Research Institute of Bioscience and Biotechnology, 52 Eoeun-Dong, Yuseong-Gu, Daejeon 305-333, Korea
| | - Seong Eon Ryu
- Medical Proteomics Research Center, Korea Research Institute of Bioscience and Biotechnology, 52 Eoeun-Dong, Yuseong-Gu, Daejeon 305-333, Korea
| | - Andrew Xiao
- Laboratory of Chromatin Biology, The Rockefeller University, New York, New York 10065
| | - C David Allis
- Laboratory of Chromatin Biology, The Rockefeller University, New York, New York 10065
| | - Seung Jun Kim
- Medical Proteomics Research Center, Korea Research Institute of Bioscience and Biotechnology, 52 Eoeun-Dong, Yuseong-Gu, Daejeon 305-333, Korea.
| | - Nicholas K Tonks
- From the Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724.
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177
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Kim JS, Huang TY, Bokoch GM. Reactive oxygen species regulate a slingshot-cofilin activation pathway. Mol Biol Cell 2009; 20:2650-60. [PMID: 19339277 DOI: 10.1091/mbc.e09-02-0131] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cellular stimuli generate reactive oxygen species (ROS) via the local action of NADPH oxidases (Nox) to modulate cytoskeletal organization and cell migration through unknown mechanisms. Cofilin is a major regulator of cellular actin dynamics whose activity is controlled by phosphorylation/dephosphorylation at Ser3. Here we show that Slingshot-1L (SSH-1L), a selective cofilin regulatory phosphatase, is involved in H(2)O(2)-induced cofilin dephosphorylation and activation. SSH-1L is activated by its release from a regulatory complex with 14-3-3zeta protein through the redox-mediated oxidation of 14-3-3zeta by H(2)O(2). The ROS-dependent activation of the SSH-1L-cofilin pathway stimulates the SSH-1L-dependent formation of cofilin-actin rods in cofilin-GFP-expressing HeLa cells. Similarly, the formation of endogenous ROS stimulated by angiotensin II (AngII) also activates the SSH-1L-cofilin pathway via oxidation of 14-3-3zeta to increase AngII-induced membrane ruffling and cell motility. These results suggest that the formation of ROS by NADPH oxidases engages a SSH-1L-cofilin pathway to regulate cytoskeletal organization and cell migration.
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Affiliation(s)
- Jun-Sub Kim
- Department of Immunology and Microbial Science and Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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178
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Abstract
DUSPs (dual-specificity phosphatases) are a heterogeneous group of protein phosphatases that can dephosphorylate both phosphotyrosine and phosphoserine/phosphothreonine residues within the one substrate. DUSPs have been implicated as major modulators of critical signalling pathways that are dysregulated in various diseases. DUSPs can be divided into six subgroups on the basis of sequence similarity that include slingshots, PRLs (phosphatases of regenerating liver), Cdc14 phosphatases (Cdc is cell division cycle), PTENs (phosphatase and tensin homologues deleted on chromosome 10), myotubularins, MKPs (mitogen-activated protein kinase phosphatases) and atypical DUSPs. Of these subgroups, a great deal of research has focused on the characterization of the MKPs. As their name suggests, MKPs dephosphorylate MAPK (mitogen-activated protein kinase) proteins ERK (extracellular-signal-regulated kinase), JNK (c-Jun N-terminal kinase) and p38 with specificity distinct from that of individual MKP proteins. Atypical DUSPs are mostly of low-molecular-mass and lack the N-terminal CH2 (Cdc25 homology 2) domain common to MKPs. The discovery of most atypical DUSPs has occurred in the last 6 years, which has initiated a large amount of interest in their role and regulation. In the past, atypical DUSPs have generally been grouped together with the MKPs and characterized for their role in MAPK signalling cascades. Indeed, some have been shown to dephosphorylate MAPKs. The current literature hints at the potential of the atypical DUSPs as important signalling regulators, but is crowded with conflicting reports. The present review provides an overview of the DUSP family before focusing on atypical DUSPs, emerging as a group of proteins with vastly diverse substrate specificity and function.
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179
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Huang TY, Minamide LS, Bamburg JR, Bokoch GM. Chronophin mediates an ATP-sensing mechanism for cofilin dephosphorylation and neuronal cofilin-actin rod formation. Dev Cell 2009; 15:691-703. [PMID: 19000834 DOI: 10.1016/j.devcel.2008.09.017] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 08/11/2008] [Accepted: 09/30/2008] [Indexed: 01/25/2023]
Abstract
Actin and its key regulatory component, cofilin, are found together in large rod-shaped assemblies in neurons subjected to energy stress. Such inclusions are also enriched in Alzheimer's disease brain, and appear in transgenic models of neurodegeneration. Neuronal insults, such as energy loss and/or oxidative stress, result in rapid dephosphorylation of the cellular cofilin pool prior to its assembly into rod-shaped inclusions. Although these events implicate a role for phosphatases in cofilin rod formation, a mechanism linking energy stress, phosphocofilin turnover, and subsequent rod assembly has been elusive. We demonstrate the ATP-sensitive interaction of the cofilin phosphatase chronophin (CIN) with the chaperone hsp90 to form a biosensor that mediates cofilin/actin rod formation. Our results suggest a model whereby attenuated interactions between CIN and hsp90 during ATP depletion enhance CIN-dependent cofilin dephosphorylation and consequent rod assembly, thereby providing a mechanism for the formation of pathological actin/cofilin aggregates during neurodegenerative energy flux.
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Affiliation(s)
- Timothy Y Huang
- Departments of Immunology and Microbial Science, and of Cell Biology, The Scripps Research Institute, IMM14, 10550 N. Torrey Pines Rd., La Jolla, CA 92122, USA
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180
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Won KJ, Park SH, Park T, Lee CK, Lee HM, Choi WS, Kim SJ, Park PJ, Jang HK, Kim SH, Kim B. Cofilin phosphorylation mediates proliferation in response to platelet-derived growth factor-BB in rat aortic smooth muscle cells. J Pharmacol Sci 2009; 108:372-9. [PMID: 19023180 DOI: 10.1254/jphs.fp0072354] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Cofilin, an actin-binding protein, is essential for a variety of cell responses. In this study, we investigated the correlation between proliferation and cofilin phosphorylation in response to platelet-derived growth factor (PDGF) in rat aortic smooth muscle cells (RASMCs). The phosphorylation of cofilin and activity of mitogen-activated protein kinase (MAPK) were measured by Western analyses and proliferation in RASMCs was measured by BrdU incorporation assays. The phosphorylation of cofilin in RASMCs was decreased by PDGF-BB treatment at 10 min, but recovered to the level of the quiescent state at 60 min. PDGF-BB-induced dephosphorylation of cofilin was inhibited by pretreatment with piceatannol (a spleen tyrosine kinase [Syk] inhibitor), PP2 (a Src inhibitor), or SP600125 (a c-Jun N-terminal kinase [JNK] inhibitor), but not by PD98059, an inhibitor of extracellular signal-regulated kinase 1/2. PDGF-BB increased JNK activity and proliferation, and these responses were suppressed by kinase inhibitors and small interference RNA-cofilin. The results suggest that PDGF-BB-induced dephosphorylation of cofilin can be promoted via the JNK pathway, which is regulated by both Syk and Src kinases and that cofilin dephosphorylation may be involved in PDGF-BB-induced RASMC proliferation.
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Affiliation(s)
- Kyung-Jong Won
- Institute of Medical Sciences, School of Medicine, Konkuk University, Chungju, Korea
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181
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Frantz C, Barreiro G, Dominguez L, Chen X, Eddy R, Condeelis J, Kelly MJS, Jacobson MP, Barber DL. Cofilin is a pH sensor for actin free barbed end formation: role of phosphoinositide binding. ACTA ACUST UNITED AC 2008; 183:865-79. [PMID: 19029335 PMCID: PMC2592832 DOI: 10.1083/jcb.200804161] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Newly generated actin free barbed ends at the front of motile cells provide sites for actin filament assembly driving membrane protrusion. Growth factors induce a rapid biphasic increase in actin free barbed ends, and we found both phases absent in fibroblasts lacking H(+) efflux by the Na-H exchanger NHE1. The first phase is restored by expression of mutant cofilin-H133A but not unphosphorylated cofilin-S3A. Constant pH molecular dynamics simulations and nuclear magnetic resonance (NMR) reveal pH-sensitive structural changes in the cofilin C-terminal filamentous actin binding site dependent on His133. However, cofilin-H133A retains pH-sensitive changes in NMR spectra and severing activity in vitro, which suggests that it has a more complex behavior in cells. Cofilin activity is inhibited by phosphoinositide binding, and we found that phosphoinositide binding is pH-dependent for wild-type cofilin, with decreased binding at a higher pH. In contrast, phosphoinositide binding by cofilin-H133A is attenuated and pH insensitive. These data suggest a molecular mechanism whereby cofilin acts as a pH sensor to mediate a pH-dependent actin filament dynamics.
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Affiliation(s)
- Christian Frantz
- Department of Cell and Tissue Biology, University of California, San Francisco, CA 94143, USA
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182
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Expression and purification of the active variant of recombinant murine Golli-interacting protein (GIP)—characterization of its phosphatase activity and interaction with Golli-BG21. Protein Expr Purif 2008; 62:36-43. [DOI: 10.1016/j.pep.2008.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 06/16/2008] [Accepted: 06/17/2008] [Indexed: 11/18/2022]
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183
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Cronin A, Homburg S, Dürk H, Richter I, Adamska M, Frère F, Arand M. Insights into the Catalytic Mechanism of Human sEH Phosphatase by Site-Directed Mutagenesis and LC–MS/MS Analysis. J Mol Biol 2008; 383:627-40. [DOI: 10.1016/j.jmb.2008.08.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 08/13/2008] [Accepted: 08/20/2008] [Indexed: 10/21/2022]
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184
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Wu Y, Yoder A, Yu D, Wang W, Liu J, Barrett T, Wheeler D, Schlauch K. Cofilin activation in peripheral CD4 T cells of HIV-1 infected patients: a pilot study. Retrovirology 2008; 5:95. [PMID: 18928553 PMCID: PMC2576353 DOI: 10.1186/1742-4690-5-95] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 10/17/2008] [Indexed: 01/15/2023] Open
Abstract
Cofilin is an actin-depolymerizing factor that regulates actin dynamics critical for T cell migration and T cell activation. In unstimulated resting CD4 T cells, cofilin exists largely as a phosphorylated inactive form. Previously, we demonstrated that during HIV-1 infection of resting CD4 T cells, the viral envelope-CXCR4 signaling activates cofilin to overcome the static cortical actin restriction. In this pilot study, we have extended this in vitro observation and examined cofilin phosphorylation in resting CD4 T cells purified from the peripheral blood of HIV-1-infected patients. Here, we report that the resting T cells from infected patients carry significantly higher levels of active cofilin, suggesting that these resting cells have been primed in vivo in cofilin activity to facilitate HIV-1 infection. HIV-1-mediated aberrant activation of cofilin may also lead to abnormalities in T cell migration and activation that could contribute to viral pathogenesis.
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Affiliation(s)
- Yuntao Wu
- Department of Molecular and Microbiology, George Mason University, Manassas, VA, 20110, USA.
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185
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HIV envelope-CXCR4 signaling activates cofilin to overcome cortical actin restriction in resting CD4 T cells. Cell 2008; 134:782-92. [PMID: 18775311 DOI: 10.1016/j.cell.2008.06.036] [Citation(s) in RCA: 229] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 03/17/2008] [Accepted: 06/14/2008] [Indexed: 01/29/2023]
Abstract
Binding of the HIV envelope to the chemokine coreceptors triggers membrane fusion and signal transduction. The fusion process has been well characterized, yet the role of coreceptor signaling remains elusive. Here, we describe a critical function of the chemokine coreceptor signaling in facilitating HIV infection of resting CD4 T cells. We find that static cortical actin in resting T cells represents a restriction and that HIV utilizes the Galphai-dependent signaling from the chemokine coreceptor CXCR4 to activate a cellular actin-depolymerizing factor, cofilin, to overcome this restriction. HIV envelope-mediated cofilin activation and actin dynamics are important for a postentry process that leads to viral nuclear localization. Inhibition of HIV-mediated actin rearrangement markedly diminishes viral latent infection of resting T cells. Conversely, induction of active cofilin greatly facilitates it. These findings shed light on viral exploitation of cellular machinery in resting T cells, where chemokine receptor signaling becomes obligatory.
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186
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Kurita S, Watanabe Y, Gunji E, Ohashi K, Mizuno K. Molecular dissection of the mechanisms of substrate recognition and F-actin-mediated activation of cofilin-phosphatase Slingshot-1. J Biol Chem 2008; 283:32542-52. [PMID: 18809681 DOI: 10.1074/jbc.m804627200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Slingshot-1 (SSH1), a member of a dual-specificity protein phosphatase family, regulates actin dynamics by dephosphorylating and reactivating cofilin, an actin-depolymerizing factor. SSH1 has the SSH family-specific, N-terminal, noncatalytic (SSH-N) domain, consisting of the A and B subdomains. SSH1 is activated by binding to actin filaments. In this study, we examined the mechanisms of SSH1 substrate recognition of phospho-cofilin (P-cofilin) and SSH1 activation by F-actin. We found that P-cofilin binds to a phosphatase-inactive mutant, SSH1(CS), in which the catalytic Cys-393 is replaced by Ser. Using a series of deletion mutants, we provided evidence that both the phosphatase (P) domain and the adjacent B domain are indispensable for P-cofilin binding of SSH1(CS) and cofilin-phosphatase activity of SSH1. In contrast, the A domain is required for the F-actin-mediated activation of SSH1, but not for P-cofilin binding or basal cofilin-phosphatase activity. The P domain alone is sufficient for the phosphatase activity toward p-nitrophenyl phosphate (pNPP), indicating that the SSH-N domain is not essential for the basal phosphatase activity of SSH1. Addition of F-actin increased the cofilin-phosphatase activity of SSH1 more than 1200-fold, but the pNPP-phosphatase activity only 2.2-fold, which suggests that F-actin principally affects the cofilin-specific phosphatase activity of SSH1. When expressed in cultured cells, SSH1, but not its mutant deleted of SSH-N, accumulated in the rear of the lamellipodium. Together, these findings suggest that the conserved SSH-N domain plays critical roles in P-cofilin recognition, F-actin-mediated activation, and subcellular localization of SSH1.
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Affiliation(s)
- Souichi Kurita
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
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187
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Baldwin JC, Karthikeyan AS, Cao A, Raghothama KG. Biochemical and molecular analysis of LePS2;1: a phosphate starvation induced protein phosphatase gene from tomato. PLANTA 2008; 228:273-80. [PMID: 18458947 DOI: 10.1007/s00425-008-0736-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Accepted: 04/05/2008] [Indexed: 05/08/2023]
Abstract
Adaptation of plants to phosphate (Pi) deficiency is a complex process involving host of biochemical changes. These changes are integrated at transcriptional level by Pi starvation mediated signal transduction pathway. Many of the signaling processes are regulated by reversible protein phosphorylation directed by protein kinases and protein phosphatases. In this study, we report the characterization of a protein phosphatase gene (LePS2;1) from tomato induced during phosphate starvation. The bacterially expressed recombinant LePS2;1 protein readily dephosphorylated a synthetic phospho-Ser/Thr peptide. Okadaic acid, an inhibitor of Ser/Thr protein phosphatases, suppressed the enzyme activity. Western blot analysis revealed the Pi starvation dependent accumulation of LePS2;1 protein. Over-expression of LePS2;1 in tomato plants resulted in increased anthocyanin accumulation and acid phosphatase activity under Pi sufficient condition. Transgenic plants exhibited distinct changes in morphology and delayed flower initiation. These results provide evidence that the protein phosphatase LePS2;1, plays an important role in phosphate starvation induced processes in tomato. To our knowledge this is the first comprehensive analysis of a protein phosphatase induced during phosphate starvation.
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Affiliation(s)
- James C Baldwin
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA
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188
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Kilian P, Campbell S, Bilodeau L, Guimond MO, Roberge C, Gallo-Payet N, Payet MD. Angiotensin II type 2 receptor stimulation increases the rate of NG108-15 cell migration via actin depolymerization. Endocrinology 2008; 149:2923-33. [PMID: 18326001 DOI: 10.1210/en.2007-0313] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Angiotensin II (Ang II) has been reported to induce migration in neuronal cell types. Using time-lapse microscopy, we show here that Ang II induces acceleration in NG108-15 cell migration. This effect was antagonized by PD123319, a selective AT2 receptor antagonist, but not by DUP753, a selective AT1 receptor antagonist, and was mimicked by the specific AT2 receptor agonist CGP42112. This Ang II-induced acceleration was not sensitive to the inhibition of previously described signaling pathways of the AT2 receptor, guanylyl cyclase/cyclic GMP or p42/p44 mapk cascades, but was abolished by pertussis toxin treatment and involved PP2A activation. Immunofluorescence studies indicate that Ang II or CGP42112 decreased the amount of filamentous actin at the leading edge of the cells. This decrease was accompanied by a concomitant increase in globular actin levels. Regulation of actin turnover in actin-based motile systems is known to be mainly under the control of the actin depolymerizing factor and cofilin. Basal migration speed decreased by 77.2% in cofilin-1 small interfering RNA-transfected NG108-15 cells, along with suppression of the effect of Ang II. In addition, the Ang II-induced increase in cell velocity was abrogated in serum-free medium as well as by genistein or okadaic acid treatment in a serum-containing medium. Such results indicate that the AT2 receptor increases the migration speed of NG108-15 cells and involves a tyrosine kinase activity, followed by phosphatase activation, which may be of the PP2A type. Therefore, the present study identifies actin depolymerization and cofilin as new targets of AT2 receptor action, in the context of cellular migration.
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Affiliation(s)
- Peter Kilian
- Département de Physiologie et Biophysique, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke 3001, 12 Avenue Nord, Sherbrooke, Québec, Canada J1H 5N4
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189
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Van Troys M, Huyck L, Leyman S, Dhaese S, Vandekerkhove J, Ampe C. Ins and outs of ADF/cofilin activity and regulation. Eur J Cell Biol 2008; 87:649-67. [PMID: 18499298 DOI: 10.1016/j.ejcb.2008.04.001] [Citation(s) in RCA: 253] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 03/25/2008] [Accepted: 04/02/2008] [Indexed: 12/15/2022] Open
Abstract
The actin-binding proteins of the actin-depolymerisation factor (ADF)/cofilin family were first described more than three decades ago, but research on these proteins still occupies a front role in the actin and cell migration field. Moreover, cofilin activity is implicated in the malignant, invasive properties of cancer cells. The effects of ADF/cofilins on actin dynamics are diverse and their regulation is complex. In stimulated cells, multiple signalling pathways can be initiated resulting in different activation/deactivation switches that control ADF/cofilin activity. The output of this entire regulatory system, in combination with spatial and temporal segregation of the activation mechanisms, underlies the contribution of ADF/cofilins to various cell migration/invasion phenotypes. In this framework, we describe current views on how ADF/cofilins function in migrating and invading cells.
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190
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Kousaka K, Kiyonari H, Oshima N, Nagafuchi A, Shima Y, Chisaka O, Uemura T. Slingshot-3 dephosphorylates ADF/cofilin but is dispensable for mouse development. Genesis 2008; 46:246-55. [DOI: 10.1002/dvg.20389] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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191
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Potential role of pyridoxal-5'-phosphate phosphatase/chronopin in epilepsy. Exp Neurol 2008; 211:128-40. [PMID: 18346735 DOI: 10.1016/j.expneurol.2008.01.029] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 01/18/2008] [Accepted: 01/18/2008] [Indexed: 11/20/2022]
Abstract
Changes in actin dynamics and pyridoxal-5'-phosphate (PLP) metabolisms are closely related to the pathophysiological profiles of the epileptic hippocampus. Recently, it has been reported that PLP phosphatase/chronophin (PLPP/CIN) directly dephosphorylates actin-depolymerizing factor (ADF)/cofilin as well as PLP. In the present study, therefore, we have investigated whether PLPP/CIN is linked to the dynamics of actin filament assembly and the excitability in the rat hippocampus. In control animals, pyridoxine chloride (PNP) treatment increased PLPP/CIN immunoreactivity only in astrocytes, which did not affect electrophysiological properties. Following status epilepticus, the PLPP/CIN protein level increased in granule cells and reactive astrocytes. These changes in PLPP/CIN protein level showed an inverse correlation with phospho-ADF (pADF)/cofilin levels and F-actin content. These changes were also accompanied by alterations in the excitability ratio and paired-pulse inhibition. Transduction of PLPP/CIN by Tat-PLPP/CIN showed similar effects on pADF/cofilin levels, F-actin content and excitability ratio in normal animals. These findings suggest that PLPP/CIN-mediated actin dynamics may play an important role in the changes of morphological properties and excitability of the epileptic hippocampus.
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192
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Kerk D, Templeton G, Moorhead GBG. Evolutionary radiation pattern of novel protein phosphatases revealed by analysis of protein data from the completely sequenced genomes of humans, green algae, and higher plants. PLANT PHYSIOLOGY 2008; 146:351-67. [PMID: 18156295 PMCID: PMC2245839 DOI: 10.1104/pp.107.111393] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In addition to the major serine/threonine-specific phosphoprotein phosphatase, Mg(2+)-dependent phosphoprotein phosphatase, and protein tyrosine phosphatase families, there are novel protein phosphatases, including enzymes with aspartic acid-based catalysis and subfamilies of protein tyrosine phosphatases, whose evolutionary history and representation in plants is poorly characterized. We have searched the protein data sets encoded by the well-finished nuclear genomes of the higher plants Arabidopsis (Arabidopsis thaliana) and Oryza sativa, and the latest draft data sets from the tree Populus trichocarpa and the green algae Chlamydomonas reinhardtii and Ostreococcus tauri, for homologs to several classes of novel protein phosphatases. The Arabidopsis proteins, in combination with previously published data, provide a complete inventory of known types of protein phosphatases in this organism. Phylogenetic analysis of these proteins reveals a pattern of evolution where a diverse set of protein phosphatases was present early in the history of eukaryotes, and the division of plant and animal evolution resulted in two distinct sets of protein phosphatases. The green algae occupy an intermediate position, and show similarity to both plants and animals, depending on the protein. Of specific interest are the lack of cell division cycle (CDC) phosphatases CDC25 and CDC14, and the seeming adaptation of CDC14 as a protein interaction domain in higher plants. In addition, there is a dramatic increase in proteins containing RNA polymerase C-terminal domain phosphatase-like catalytic domains in the higher plants. Expression analysis of Arabidopsis phosphatase genes differentially amplified in plants (specifically the C-terminal domain phosphatase-like phosphatases) shows patterns of tissue-specific expression with a statistically significant number of correlated genes encoding putative signal transduction proteins.
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Affiliation(s)
- David Kerk
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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193
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Abstract
The establishment of polarity is an essential process in early neuronal development. Although a number of molecules controlling neuronal polarity have been identified, genetic evidence about their physiological roles in this process is mostly lacking. We analyzed the consequences of loss of Cdc42, a central regulator of polarity in multiple systems, on the polarization of mammalian neurons. Genetic ablation of Cdc42 in the brain led to multiple abnormalities, including striking defects in the formation of axonal tracts. Neurons from the Cdc42 null animals sprouted neurites but had a strongly suppressed ability to form axons both in vivo and in culture. This was accompanied by disrupted cytoskeletal organization, enlargement of the growth cones, and inhibition of filopodial dynamics. Axon formation in the knock-out neurons was rescued by manipulation of the actin cytoskeleton, indicating that the effects of Cdc42 ablation are exerted through modulation of actin dynamics. In addition, the knock-outs showed a specific increase in the phosphorylation (inactivation) of the Cdc42 effector cofilin. Furthermore, the active, nonphosphorylated form of cofilin was enriched in the axonal growth cones of wild-type, but not of mutant, neurons. Importantly, cofilin knockdown resulted in polarity defects quantitatively analogous to the ones seen after Cdc42 ablation. We conclude that Cdc42 is a key regulator of axon specification, and that cofilin is a physiological downstream effector of Cdc42 in this process.
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194
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Lee K, Lee K, Kim B, Lim J, Koo J, Lee M, Lee HM, Lee CK, Won KJ. Propofol Inhibits Platelet-derived Growth Factor-stimulated Migration in Rat Aortic Smooth Muscle Cells. Korean J Anesthesiol 2008. [DOI: 10.4097/kjae.2008.54.3.s22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Kyuchang Lee
- Department of Anesthesiology and Pain Medicine, College of Medicine, Konkuk University, Chungju, Korea
| | - Keunsang Lee
- Department of Anesthesiology and Pain Medicine, College of Medicine, Konkuk University, Chungju, Korea
| | - Bokyung Kim
- Department of Physiology, College of Medicine, Konkuk University, Chungju, Korea
| | - Jeongae Lim
- Department of Anesthesiology and Pain Medicine, College of Medicine, Konkuk University, Chungju, Korea
| | - Jaiwon Koo
- Department of Anesthesiology and Pain Medicine, College of Medicine, Konkuk University, Chungju, Korea
| | - Myeongjong Lee
- Department of Anesthesiology and Pain Medicine, College of Medicine, Konkuk University, Chungju, Korea
| | - Hwan Myung Lee
- Department of Physiology, College of Medicine, Konkuk University, Chungju, Korea
| | - Chang-Kwon Lee
- Department of Physiology, College of Medicine, Konkuk University, Chungju, Korea
| | - Kyung-Jong Won
- Department of Physiology, College of Medicine, Konkuk University, Chungju, Korea
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195
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San Martín A, Lee MY, Williams HC, Mizuno K, Lassègue B, Griendling KK. Dual regulation of cofilin activity by LIM kinase and Slingshot-1L phosphatase controls platelet-derived growth factor-induced migration of human aortic smooth muscle cells. Circ Res 2007; 102:432-8. [PMID: 18096821 DOI: 10.1161/circresaha.107.158923] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Platelet-derived growth factor (PDGF) plays a central role in vascular healing, atherosclerosis, and restenosis, partly by stimulating vascular smooth muscle cell (VSMC) migration. Migration requires rapid turnover of actin filaments, which is partially controlled by cofilin. Although cofilin is negatively regulated by Ser3 phosphorylation, the upstream signaling pathways have not been defined, nor has its role in VSMC migration been studied. We hypothesized that PDGF-induced migration of VSMCs involves cofilin activation and that this is regulated by the serine kinase LIM kinase (LIMK) and the novel phosphatase Slingshot (SSH)1L. In human VSMCs, stimulation with PDGF increased G-actin incorporation into the actin cytoskeleton. PDGF transiently activated the cofilin kinase, LIMK, with a peak at 5 minutes. However, cofilin was dephosphorylated between 5 and 45 minutes, with a maximum of 43+/-5% dephosphorylation at 30 minutes, suggesting that PDGF also activates a cofilin phosphatase. We found that VSMCs express SSH1L, which is induced and activated (564+/-73 versus 1021+/-141 picomoles of PO(4); P=0.015) by PDGF. Of importance, small interfering RNA directed against SSH1L blocked cofilin dephosphorylation and decreased migration (528+/-33 versus 318+/-25 cells/field; P<0.01). Taken together, our results suggest that PDGF participates in actin dynamics by dual regulation of cofilin activity via LIMK and SSH1L.
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Affiliation(s)
- Alejandra San Martín
- Division of Cardiology, Emory University, 1639 Pierce Dr, 319 WMB, Atlanta, GA 30322, USA
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196
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Sidani M, Wessels D, Mouneimne G, Ghosh M, Goswami S, Sarmiento C, Wang W, Kuhl S, El-Sibai M, Backer JM, Eddy R, Soll D, Condeelis J. Cofilin determines the migration behavior and turning frequency of metastatic cancer cells. ACTA ACUST UNITED AC 2007; 179:777-91. [PMID: 18025308 PMCID: PMC2080932 DOI: 10.1083/jcb.200707009] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have investigated the effects of inhibiting the expression of cofilin to understand its role in protrusion dynamics in metastatic tumor cells, in particular. We show that the suppression of cofilin expression in MTLn3 cells (an apolar randomly moving amoeboid metastatic tumor cell) caused them to extend protrusions from only one pole, elongate, and move rectilinearly. This remarkable transformation was correlated with slower extension of fewer, more stable lamellipodia leading to a reduced turning frequency. Hence, the loss of cofilin caused an amoeboid tumor cell to assume a mesenchymal-type mode of movement. These phenotypes were correlated with the loss of uniform chemotactic sensitivity of the cell surface to EGF stimulation, demonstrating that to chemotax efficiently, a cell must be able to respond to chemotactic stimulation at any region on its surface. The changes in cell shape, directional migration, and turning frequency were related to the re-localization of Arp2/3 complex to one pole of the cell upon suppression of cofilin expression.
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Affiliation(s)
- Mazen Sidani
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA.
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197
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Almo SC, Bonanno JB, Sauder JM, Emtage S, Dilorenzo TP, Malashkevich V, Wasserman SR, Swaminathan S, Eswaramoorthy S, Agarwal R, Kumaran D, Madegowda M, Ragumani S, Patskovsky Y, Alvarado J, Ramagopal UA, Faber-Barata J, Chance MR, Sali A, Fiser A, Zhang ZY, Lawrence DS, Burley SK. Structural genomics of protein phosphatases. ACTA ACUST UNITED AC 2007; 8:121-40. [PMID: 18058037 DOI: 10.1007/s10969-007-9036-1] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Accepted: 11/06/2007] [Indexed: 12/11/2022]
Abstract
The New York SGX Research Center for Structural Genomics (NYSGXRC) of the NIGMS Protein Structure Initiative (PSI) has applied its high-throughput X-ray crystallographic structure determination platform to systematic studies of all human protein phosphatases and protein phosphatases from biomedically-relevant pathogens. To date, the NYSGXRC has determined structures of 21 distinct protein phosphatases: 14 from human, 2 from mouse, 2 from the pathogen Toxoplasma gondii, 1 from Trypanosoma brucei, the parasite responsible for African sleeping sickness, and 2 from the principal mosquito vector of malaria in Africa, Anopheles gambiae. These structures provide insights into both normal and pathophysiologic processes, including transcriptional regulation, regulation of major signaling pathways, neural development, and type 1 diabetes. In conjunction with the contributions of other international structural genomics consortia, these efforts promise to provide an unprecedented database and materials repository for structure-guided experimental and computational discovery of inhibitors for all classes of protein phosphatases.
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Affiliation(s)
- Steven C Almo
- Albert Einstein College of Medicine, Bronx, NY, USA.
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198
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Estornes Y, Gay F, Gevrey JC, Navoizat S, Nejjari M, Scoazec JY, Chayvialle JA, Saurin JC, Abello J. Differential involvement of destrin and cofilin-1 in the control of invasive properties of Isreco1 human colon cancer cells. Int J Cancer 2007; 121:2162-71. [PMID: 17583572 DOI: 10.1002/ijc.22911] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Actin depolymerizing factor (ADF)/cofilin family proteins are key regulators of actin filament turnover and cytoskeleton reorganization. The role of cofilin-1 in cell motility has been demonstrated in several cell types but remained poorly documented in the case of colon cancer. In addition, the putative function of destrin (also known as ADF) had not been explored in this context despite the fact that it is expressed in all colon cancer cell lines examined. We were therefore prompted to evaluate the respective contributions of these proteins to the invasive properties of the human colon cancer Isreco1 cell line, which expresses a comparatively high destrin/cofilin ratio. Reduction of cofilin-1 or destrin expression in Isreco1 cells using RNA interference led to an increase of the number of multinucleated cells and altered polarized lamellipodium protrusion and distribution of paxillin-containing adhesions. Both cofilin-1 and destrin silencing enhanced cell adhesion to extracellular matrix components. However, only destrin appeared to be required for cell migration on collagen I and for cell invasion through Matrigel in response to the proinvasive neuroendocrine peptide bombesin. This differential functional involvement was supported by a destrin-dependent, cofilin-independent phosphorylation of p130Crk-associated substrate (p130Cas) upon cell adhesion to collagen I or Matrigel. Taken together, our results suggest that destrin is a significant regulator of various processes important for invasive phenotype of human colon cancer Isreco1 cells whereas cofilin-1 may be involved in only a subset of them.
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199
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Komalavilas P, Penn RB, Flynn CR, Thresher J, Lopes LB, Furnish EJ, Guo M, Pallero MA, Murphy-Ullrich JE, Brophy CM. The small heat shock-related protein, HSP20, is a cAMP-dependent protein kinase substrate that is involved in airway smooth muscle relaxation. Am J Physiol Lung Cell Mol Physiol 2007; 294:L69-78. [PMID: 17993590 DOI: 10.1152/ajplung.00235.2007] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of the cAMP/cAMP-dependent PKA pathway leads to relaxation of airway smooth muscle (ASM). The purpose of this study was to examine the role of the small heat shock-related protein HSP20 in mediating PKA-dependent ASM relaxation. Human ASM cells were engineered to constitutively express a green fluorescent protein-PKA inhibitory fusion protein (PKI-GFP) or GFP alone. Activation of the cAMP-dependent signaling pathways by isoproterenol (ISO) or forskolin led to increases in the phosphorylation of HSP20 in GFP but not PKI-GFP cells. Forskolin treatment in GFP but not PKI-GFP cells led to a loss of central actin stress fibers and decreases in the number of focal adhesion complexes. This loss of stress fibers was associated with dephosphorylation of the actin-depolymerizing protein cofilin in GFP but not PKI-GFP cells. To confirm that phosphorylated HSP20 plays a role in PKA-induced ASM relaxation, intact strips of bovine ASM were precontracted with serotonin followed by ISO. Activation of the PKA pathway led to relaxation of bovine ASM, which was associated with phosphorylation of HSP20 and dephosphorylation of cofilin. Finally, treatment with phosphopeptide mimetics of HSP20 possessing a protein transduction domain partially relaxed precontracted bovine ASM strips. In summary, ISO-induced phosphorylation of HSP20 or synthetic phosphopeptide analogs of HSP20 decreases phosphorylation of cofilin and disrupts actin in ASM, suggesting that one possible mechanism by which HSP20 mediates ASM relaxation is via regulation of actin filament dynamics.
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Affiliation(s)
- Padmini Komalavilas
- Center for Metabolic Biology, College of Liberal Arts and Sciences, Arizona State University, PO Box 873704, Tempe, AZ 85287-3704, USA.
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200
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Kligys K, Claiborne JN, DeBiase PJ, Hopkinson SB, Wu Y, Mizuno K, Jones JCR. The slingshot family of phosphatases mediates Rac1 regulation of cofilin phosphorylation, laminin-332 organization, and motility behavior of keratinocytes. J Biol Chem 2007; 282:32520-8. [PMID: 17848544 PMCID: PMC2754063 DOI: 10.1074/jbc.m707041200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The motility of keratinocytes is an essential component of wound closure and the development of epidermal tumors. In vitro, the specific motile behavior of keratinocytes is dictated by the assembly of laminin-332 tracks, a process that is dependent upon alpha6beta4 integrin signaling to Rac1 and the actin-severing protein cofilin. Here we have analyzed how cofilin phosphorylation is regulated by phosphatases (slingshot (SSH) or chronophin (CIN)) downstream of signaling by alpha6beta4 integrin/Rac1 in human keratinocytes. Keratinocytes express all members of the SSH family (SSH1, SSH2, and SSH3) and CIN. However, expression of phosphatase-dead versions of all three SSH proteins, but not dominant inactive CIN, results in phosphorylation/inactivation of cofilin, changes in actin cytoskeleton organization, loss of cell polarity, and assembly of aberrant arrays of laminin-332 in human keratinocytes. SSH activity is regulated by 14-3-3 protein binding, and intriguingly, 14-3-3/alpha6beta4 integrin protein interaction is required for keratinocyte migration. We wondered whether 14-3-3 proteins function as regulators of Rac1-mediated keratinocyte migration patterns. In support of this hypothesis, inhibition of Rac1 results in an increase in 14-3-3 protein association with SSH. Thus, we propose a novel mechanism in which alpha6beta4 integrin signaling via Rac1, 14-3-3 proteins, and SSH family members regulates cofilin activation, cell polarity, and matrix assembly, leading to specific epidermal cell migration behavior.
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Affiliation(s)
- Kristina Kligys
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Jessica N. Claiborne
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Phillip J. DeBiase
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Susan B. Hopkinson
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Yvonne Wu
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Kensaku Mizuno
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Jonathan C. R. Jones
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
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