scholarly journals Inhibition of platelet function by targeting the platelet cytoskeleton via the LIMK-signaling pathway

2018 ◽  
Author(s):  
Juliana Antonipillai ◽  
Sheena Rigby ◽  
Nicole Bassler ◽  
Karlheinz Peter ◽  
Ora Bernard
Keyword(s):  
Platelet Function ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Lim Kinase ◽  
Cellular Processes ◽  
New Strategy ◽  
Platelet Aggregates ◽  
Dynamic Structures ◽  
Shape Changes ◽  
Platelet Shape

AbstractActin is highly abundant in platelets, and platelet function is dependent on actin structures. Actin filaments are dynamic structures involved in many cellular processes including platelet shape changes and adhesion. The actin cytoskeleton is tightly regulated by actin-binding proteins, which include the members of the actin depolymerising factor (ADF)/cofilin family. LIM kinase (LIMK) and slingshot phosphatase (SSH-1L) regulate actin dynamics by controlling the binding affinity of ADF/cofilin towards actin. We hypothesised that inhibition of LIMK activity may prevent the changes in platelet shape during their activation and therefore their function by controlling the dynamics of Factin. Therefore, inhibition of LIMK activity may represent an attractive new strategy to control and inhibit platelet function; particularly the formation of stable platelet aggregates and thus stable thrombi.

scholarly journals Platelet adhesion: Structural and functional diversity of short dystrophin and utrophins in the formation of dystrophinassociated-protein complexes related to actin dynamics

2005 ◽  
Vol 94 (12) ◽  
pp. 1203-1212 ◽  
Author(s):  
Doris Cerecedo ◽  
Dalila Martínez-Rojas ◽  
Oscar Chávez ◽  
Francisco Martínez-Pérez ◽  
Francisco García-Sierra ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Platelet Adhesion ◽  
Protein Complexes ◽  
Human Platelets ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Dynamic Cell ◽  
Associated Proteins ◽  
Coated Surfaces ◽  
Dynamic Structures

SummaryPlatelets are dynamic cell fragments that modify their shape during activation. Utrophin and dystrophins are minor actin-binding proteins present in muscle and non-muscle cytoskeleton. In the present study, we characterised the pattern of Dp71 isoforms and utrophin gene products by immunoblot in human platelets. Two new dystrophin isoforms were found, Dp71f and Dp71d, as well as the Up71 isoform and the dystrophin-associated proteins, α and β-dystrobrevins. Distribution of Dp71d/Dp71Δ110 m, Up400/Up71 and dystrophin-associated proteins in relation to the actin cytoskeleton was evaluated by confocal microscopy in both resting and platelets adhered on glass. Formation of two dystrophin-associated protein complexes (Dp71d/Dp71Δ110 m ~DAPC and Up400/Up71~DAPC) was demonstrated by co-immunoprecipitation and their distribution in relation to the actin cytoskeleton was characterised during platelet adhesion. The Dp71d/Dp71Δ110 m ~DAPC is maintained mainly at the granulomere and is associated with dynamic structures during activation by adhesion to thrombin-coated surfaces. Participation of both Dp71d/Dp71Δ110 m ~DAPC and Up400/Up71~DAPC in the biological roles of the platelets is discussed.

scholarly journals Structure of the actin-depolymerizing factor homology domain in complex with actin

2008 ◽  
Vol 182 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Ville O. Paavilainen ◽  
Esko Oksanen ◽  
Adrian Goldman ◽  
Pekka Lappalainen
Keyword(s):  
Crystal Structure ◽  
Atomic Structure ◽  
Actin Filaments ◽  
Driving Force ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Actin Monomer ◽  
Nucleotide Exchange ◽  
Actin Depolymerizing Factor ◽  
Cellular Processes

Actin dynamics provide the driving force for many cellular processes including motility and endocytosis. Among the central cytoskeletal regulators are actin-depolymerizing factor (ADF)/cofilin, which depolymerizes actin filaments, and twinfilin, which sequesters actin monomers and caps filament barbed ends. Both interact with actin through an ADF homology (ADF-H) domain, which is also found in several other actin-binding proteins. However, in the absence of an atomic structure for the ADF-H domain in complex with actin, the mechanism by which these proteins interact with actin has remained unknown. Here, we present the crystal structure of twinfilin's C-terminal ADF-H domain in complex with an actin monomer. This domain binds between actin subdomains 1 and 3 through an interface that is conserved among ADF-H domain proteins. Based on this structure, we suggest a mechanism by which ADF/cofilin and twinfilin inhibit nucleotide exchange of actin monomers and present a model for how ADF/cofilin induces filament depolymerization by weakening intrafilament interactions.

scholarly journals Critical Roles of Phosphorylation and Actin Binding Motifs, but Not the Central Proline-rich Region, for Ena/Vasodilator-stimulated Phosphoprotein (VASP) Function during Cell Migration

2002 ◽  
Vol 13 (7) ◽  
pp. 2533-2546 ◽  
Author(s):  
Joseph J. Loureiro ◽  
Douglas A. Rubinson ◽  
James E. Bear ◽  
Gretchen A. Baltus ◽  
Adam V. Kwiatkowski ◽  
...  
Keyword(s):  
Cell Motility ◽  
Cell Movement ◽  
Protein Family ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Binding Motif ◽  
Conserved Sequence ◽  
Cellular Processes ◽  
Sequence Elements

The Ena/vasodilator-stimulated phosphoprotein (VASP) protein family is implicated in the regulation of a number of actin-based cellular processes, including lamellipodial protrusion necessary for whole cell translocation. A growing body of evidence derived largely from in vitro biochemical experiments using purified proteins, cell-free extracts, and pathogen motility has begun to suggest various mechanistic roles for Ena/VASP proteins in the control of actin dynamics. Using complementation of phenotypes in Ena/VASP-deficient cells and overexpression in normal fibroblasts, we have assayed the function of a panel of mutants in one member of this family, Mena, by mutating highly conserved sequence elements found in this protein family. Surprisingly, deletion of sites required for binding of the actin monomer-binding protein profilin, a known ligand of Ena/VASP proteins, has no effect on the ability of Mena to regulate random cell motility. Our analysis revealed two features essential for Ena/VASP function in cell movement, cyclic nucleotide-dependent kinase phosphorylation sites and an F-actin binding motif. Interestingly, expression of the C-terminal EVH2 domain alone is sufficient to complement loss of Ena/VASP function in random cell motility.

scholarly journals Diverse functions of myosin VI in spermiogenesis

2021 ◽  
Author(s):  
Przemysław Zakrzewski ◽  
Marta Lenartowska ◽  
Folma Buss
Keyword(s):  
Adaptor Proteins ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Animal Cells ◽  
C Elegans ◽  
Cellular Processes ◽  
Sperm Development ◽  
Membrane Compartments ◽  
Myosin Motors ◽  
The Many

AbstractSpermiogenesis is the final stage of spermatogenesis, a differentiation process during which unpolarized spermatids undergo excessive remodeling that results in the formation of sperm. The actin cytoskeleton and associated actin-binding proteins play crucial roles during this process regulating organelle or vesicle delivery/segregation and forming unique testicular structures involved in spermatid remodeling. In addition, several myosin motor proteins including MYO6 generate force and movement during sperm differentiation. MYO6 is highly unusual as it moves towards the minus end of actin filaments in the opposite direction to other myosin motors. This specialized feature of MYO6 may explain the many proposed functions of this myosin in a wide array of cellular processes in animal cells, including endocytosis, secretion, stabilization of the Golgi complex, and regulation of actin dynamics. These diverse roles of MYO6 are mediated by a range of specialized cargo-adaptor proteins that link this myosin to distinct cellular compartments and processes. During sperm development in a number of different organisms, MYO6 carries out pivotal functions. In Drosophila, the MYO6 ortholog regulates actin reorganization during spermatid individualization and male KO flies are sterile. In C. elegans, the MYO6 ortholog mediates asymmetric segregation of cytosolic material and spermatid budding through cytokinesis, whereas in mice, this myosin regulates assembly of highly specialized actin-rich structures and formation of membrane compartments to allow the formation of fully differentiated sperm. In this review, we will present an overview and compare the diverse function of MYO6 in the specialized adaptations of spermiogenesis in flies, worms, and mammals.

scholarly journals Plastin 3 in health and disease: a matter of balance

2021 ◽  
Author(s):  
Lisa Wolff ◽  
Eike A. Strathmann ◽  
Ilka Müller ◽  
Daniela Mählich ◽  
Charlotte Veltman ◽  
...  
Keyword(s):  
Bone Fractures ◽  
Muscular Atrophy ◽  
X Inactivation ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Specific Expression ◽  
Expression Variability ◽  
Cellular Processes ◽  
Long Time ◽  
Health And Disease

AbstractFor a long time, PLS3 (plastin 3, also known as T-plastin or fimbrin) has been considered a rather inconspicuous protein, involved in F-actin-binding and -bundling. However, in recent years, a plethora of discoveries have turned PLS3 into a highly interesting protein involved in many cellular processes, signaling pathways, and diseases. PLS3 is localized on the X-chromosome, but shows sex-specific, inter-individual and tissue-specific expression variability pointing towards skewed X-inactivation. PLS3 is expressed in all solid tissues but usually not in hematopoietic cells. When escaping X-inactivation, PLS3 triggers a plethora of different types of cancers. Elevated PLS3 levels are considered a prognostic biomarker for cancer and refractory response to therapies. When it is knocked out or mutated in humans and mice, it causes osteoporosis with bone fractures; it is the only protein involved in actin dynamics responsible for osteoporosis. Instead, when PLS3 is upregulated, it acts as a highly protective SMN-independent modifier in spinal muscular atrophy (SMA). Here, it seems to counteract reduced F-actin levels by restoring impaired endocytosis and disturbed calcium homeostasis caused by reduced SMN levels. In contrast, an upregulation of PLS3 on wild-type level might cause osteoarthritis. This emphasizes that the amount of PLS3 in our cells must be precisely balanced; both too much and too little can be detrimental. Actin-dynamics, regulated by PLS3 among others, are crucial in a lot of cellular processes including endocytosis, cell migration, axonal growth, neurotransmission, translation, and others. Also, PLS3 levels influence the infection with different bacteria, mycosis, and other pathogens.

scholarly journals Direct signaling by the BMP type II receptor via the cytoskeletal regulator LIMK1

2003 ◽  
Vol 162 (6) ◽  
pp. 1089-1098 ◽  
Author(s):  
Victoria C. Foletta ◽  
Mei Ann Lim ◽  
Juliana Soosairajah ◽  
April P. Kelly ◽  
Edouard G. Stanley ◽  
...  
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Bmp Signaling ◽  
Actin Dynamics ◽  
Tail Domain ◽  
Tail Region ◽  
Lim Kinase ◽  
Cellular Processes ◽  
Transcription Factor Activation ◽  
Smad Proteins ◽  
And Migration

Bone morphogenetic proteins (BMPs) regulate multiple cellular processes, including cell differentiation and migration. Their signals are transduced by the kinase receptors BMPR-I and BMPR-II, leading to Smad transcription factor activation via BMPR-I. LIM kinase (LIMK) 1 is a key regulator of actin dynamics as it phosphorylates and inactivates cofilin, an actin depolymerizing factor. During a search for LIMK1-interacting proteins, we isolated clones encompassing the tail region of BMPR-II. Although the BMPR-II tail is not involved in BMP signaling via Smad proteins, mutations truncating this domain are present in patients with primary pulmonary hypertension (PPH). Further analysis revealed that the interaction between LIMK1 and BMPR-II inhibited LIMK1's ability to phosphorylate cofilin, which could then be alleviated by addition of BMP4. A BMPR-II mutant containing the smallest COOH-terminal truncation described in PPH failed to bind or inhibit LIMK1. This study identifies the first function of the BMPR-II tail domain and suggests that the deregulation of actin dynamics may contribute to the etiology of PPH.

The Actin Regulator Coronin-1A Modulates Platelet Shape Change and Consolidates Arterial Thrombosis

2018 ◽  
Vol 118 (12) ◽  
pp. 2098-2111 ◽  
Author(s):  
Thomas Stocker ◽  
Joachim Pircher ◽  
Artid Skenderi ◽  
Andreas Ehrlich ◽  
Clemens Eberle ◽  
...  
Keyword(s):  
Arterial Thrombosis ◽  
Actin Polymerization ◽  
Thrombus Formation ◽  
Shape Change ◽  
Actin Binding ◽  
Cellular Processes ◽  
Reduced Density ◽  
Induced Aggregation ◽  
Platelet Shape

AbstractCoronin-1A (Coro1A) belongs to a family of highly conserved actin-binding proteins that regulate cytoskeletal re-arrangement. In mammalians, Coro1A expression is most abundant in the haematopoietic lineage, where it regulates various cellular processes. The role of Coro1A in platelets has been previously unknown. Here, we identified Coro1A in human and mouse platelets. Genetic absence of Coro1A in mouse platelets inhibited agonist-induced actin polymerization and altered cofilin phosphoregulation, leading to a reduction in spreading and low-dose collagen induced aggregation. Furthermore, Coro1A-deficient mice displayed a defect in ferric chloride-induced arterial thrombosis with prolonged thrombus formation and reduced thrombus size. Immunofluorescence analysis revealed a less compact thrombus structure with reduced density of platelets and fibrinogen. In summary, Coro1A has a role in platelet biology with impact on spreading, aggregation and thrombosis.

scholarly journals Differential interactions of the formins INF2, mDia1, and mDia2 with microtubules

2011 ◽  
Vol 22 (23) ◽  
pp. 4575-4587 ◽  
Author(s):  
Jeremie Gaillard ◽  
Vinay Ramabhadran ◽  
Emmanuelle Neumanne ◽  
Pinar Gurel ◽  
Laurent Blanchoin ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Actin Polymerization ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Differential Function ◽  
Cellular Processes ◽  
High Affinity ◽  
C Terminus ◽  
Molecular Machinery ◽  
Cytoskeletal Elements

A number of cellular processes use both microtubules and actin filaments, but the molecular machinery linking these two cytoskeletal elements remains to be elucidated in detail. Formins are actin-binding proteins that have multiple effects on actin dynamics, and one formin, mDia2, has been shown to bind and stabilize microtubules through its formin homology 2 (FH2) domain. Here we show that three formins, INF2, mDia1, and mDia2, display important differences in their interactions with microtubules and actin. Constructs containing FH1, FH2, and C-terminal domains of all three formins bind microtubules with high affinity (Kd < 100 nM). However, only mDia2 binds microtubules at 1:1 stoichiometry, with INF2 and mDia1 showing saturating binding at approximately 1:3 (formin dimer:tubulin dimer). INF2-FH1FH2C is a potent microtubule-bundling protein, an effect that results in a large reduction in catastrophe rate. In contrast, neither mDia1 nor mDia2 is a potent microtubule bundler. The C-termini of mDia2 and INF2 have different functions in microtubule interaction, with mDia2's C-terminus required for high-affinity binding and INF2's C-terminus required for bundling. mDia2's C-terminus directly binds microtubules with submicromolar affinity. These formins also differ in their abilities to bind actin and microtubules simultaneously. Microtubules strongly inhibit actin polymerization by mDia2, whereas they moderately inhibit mDia1 and have no effect on INF2. Conversely, actin monomers inhibit microtubule binding/bundling by INF2 but do not affect mDia1 or mDia2. These differences in interactions with microtubules and actin suggest differential function in cellular processes requiring both cytoskeletal elements.

scholarly journals Magnaporthe oryzae Abp1, a MoArk1 Kinase-Interacting Actin Binding Protein, Links Actin Cytoskeleton Regulation to Growth, Endocytosis, and Pathogenesis

2019 ◽  
Vol 32 (4) ◽  
pp. 437-451 ◽  
Author(s):  
Lianwei Li ◽  
Shengpei Zhang ◽  
Xinyu Liu ◽  
Rui Yu ◽  
Xinrui Li ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Magnaporthe Oryzae ◽  
Binding Protein ◽  
Normal Growth ◽  
Underlying Mechanism ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Actin Binding Protein ◽  
Cellular Processes ◽  
Blast Fungus

The actin cytoskeleton and actin-coupled endocytosis are conserved cellular processes required for the normal growth and pathogenesis of the rice blast fungus Magnaporthe oryzae. We have previously shown that actin regulating kinase MoArk1 regulates actin dynamics and endocytosis to play a key role in virulence of the fungus. To understand the underlying mechanism, we have characterized the actin-binding protein MoAbp1 that interacts with MoArk1 from M. oryzae. The ΔMoabp1 mutant exhibited delayed endocytosis and defects in growth, host penetration, and invasive growth. Consistent with its putative function associated with actin-binding, MoAbp1 regulates the localization of actin patches and plays a role in MoArk1 phosphorylation. In addition, MoAbp1 interacts with MoCap (adenylyl cyclase–associated protein) affecting its normal patch localization pattern and the actin protein MoAct1 through its conserved domains. Taken together, our results support a notion that MoAbp1 functions as a protein scaffold linking MoArk1, MoCap1, and MoAct1 to regulate actin cytoskeleton dynamics critical in growth and pathogenicity of the blast fungus.

scholarly journals Focus on ADF/Cofilin: Beyond Actin Cytoskeletal Regulation

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Cheng-Han Tsai ◽  
Yi-Jang Lee
Keyword(s):  
Cell Cycle ◽  
Signaling Pathway ◽  
Small Gtpase ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Biological Functions ◽  
Lim Kinase ◽  
Cytoskeletal Regulation ◽  
Pathophysiological Role

Actin depolymerizing factor (ADF)/cofilin, an actin-binding protein ubiquitously expressed in a variety of organisms, is required for regulation of actin dynamics. The activity of ADF/cofilin is dependent on serine 3 phosphorylation by LIM kinase (LIMK), which is regulated by the Rho small GTPase signaling pathway. ADF/cofilin is strongly associated with several important cell biological functions, including cell cycle, morphological maintenance, and locomotion. These functions affect several biological events, including embryogenesis, oncology, nephropathy, and neurodegenerations. Here, we focus on the biochemical and pathophysiological role of ADF/cofilin in mammals.

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