scholarly journals Molecular Tuning of Filamin A Activities in the Context of Adhesion and Migration

2020 ◽  
Vol 8 ◽  
Author(s):  
Isabelle Lamsoul ◽  
Loïc Dupré ◽  
Pierre G. Lutz
Keyword(s):  
Actin Cytoskeleton ◽  
Adult Life ◽  
Scaffolding Protein ◽  
Actin Binding ◽  
Filamin A ◽  
Multiple Organs ◽  
Human Disorders ◽  
Cross Links ◽  
Orthogonal Orientation ◽  
And Migration

The dynamic organization of actin cytoskeleton meshworks relies on multiple actin-binding proteins endowed with distinct actin-remodeling activities. Filamin A is a large multi-domain scaffolding protein that cross-links actin filaments with orthogonal orientation in response to various stimuli. As such it plays key roles in the modulation of cell shape, cell motility, and differentiation throughout development and adult life. The essentiality and complexity of Filamin A is highlighted by mutations that lead to a variety of severe human disorders affecting multiple organs. One of the most conserved activity of Filamin A is to bridge the actin cytoskeleton to integrins, thereby maintaining the later in an inactive state. We here review the numerous mechanisms cells have developed to adjust Filamin A content and activity and focus on the function of Filamin A as a gatekeeper to integrin activation and associated adhesion and motility.

FilGAP and its close relatives: a mediator of Rho–Rac antagonism that regulates cell morphology and migration

2013 ◽  
Vol 453 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Fumihiko Nakamura
Keyword(s):  
Actin Cytoskeleton ◽  
Gene Product ◽  
Rho Kinase ◽  
Leading Edge ◽  
Filamin A ◽  
Filamentous Actin ◽  
Rhoa Activity ◽  
Cell Protrusion ◽  
And Migration ◽  
Close Relatives

Cell migration, phagocytosis and cytokinesis are mechanically intensive cellular processes that are mediated by the dynamic assembly and contractility of the actin cytoskeleton. GAPs (GTPase-activating proteins) control activities of the Rho family proteins including Cdc42, Rac1 and RhoA, which are prominent upstream regulators of the actin cytoskeleton. The present review concerns a class of Rho GAPs, FilGAP (ARHGAP24 gene product) and its close relatives (ARHGAP22 and AHRGAP25 gene products). FilGAP is a GAP for Rac1 and a binding partner of FLNa (filamin A), a widely expressed F-actin (filamentous actin)-cross-linking protein that binds many different proteins that are important in cell regulation. Phosphorylation of FilGAP serine/threonine residues and binding to FLNa modulate FilGAP's GAP activity and, as a result, its ability to regulate cell protrusion and spreading. FLNa binds to FilGAP at F-actin-enriched sites, such as at the leading edge of the cell where Rac1 activity is controlled to inhibit actin assembly. FilGAP then dissociates from FLNa in actin networks by myosin-dependent mechanical deformation of FLNa's FilGAP-binding site to relocate at the plasma membrane by binding to polyphosphoinositides. Since actomyosin contraction is activated downstream of RhoA–ROCK (Rho-kinase), RhoA activity regulates Rac1 through FilGAP by signalling to the force-generating system. FilGAP and the ARHGAP22 gene product also act as mediators between RhoA and Rac1 pathways, which lead to amoeboid and mesenchymal modes of cell movements respectively. Therefore FilGAP and its close relatives are key regulators that promote the reciprocal inhibitory relationship between RhoA and Rac1 in cell shape changes and the mesenchymal–amoeboid transition in tumour cells.

scholarly journals IQGAP1, a Rac- and Cdc42-binding Protein, Directly Binds and Cross-links Microfilaments

1997 ◽  
Vol 137 (7) ◽  
pp. 1555-1566 ◽  
Author(s):  
Anne-Marie Bashour ◽  
Aaron T. Fullerton ◽  
Matthew J. Hart ◽  
George S. Bloom
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Filaments ◽  
Immunofluorescence Microscopy ◽  
Binding Activity ◽  
Cytochalasin D ◽  
Actin Binding ◽  
Purification And Characterization ◽  
Cross Links ◽  
Underlying Mechanisms

Activated forms of the GTPases, Rac and Cdc42, are known to stimulate formation of microfilament-rich lamellipodia and filopodia, respectively, but the underlying mechanisms have remained obscure. We now report the purification and characterization of a protein, IQGAP1, which is likely to mediate effects of these GTPases on microfilaments. Native IQGAP1 purified from bovine adrenal comprises two ∼190-kD subunits per molecule plus substoichiometric calmodulin. Purified IQGAP1 bound directly to F-actin and cross-linked the actin filaments into irregular, interconnected bundles that exhibited gel-like properties. Exogenous calmodulin partially inhibited binding of IQGAP1 to F-actin, and was more effective in the absence, than in the presence of calcium. Immunofluorescence microscopy demonstrated cytochalasin D–sensitive colocalization of IQGAP1 with cortical microfilaments. These results, in conjunction with prior evidence that IQGAP1 binds directly to activated Rac and Cdc42, suggest that IQGAP1 serves as a direct molecular link between these GTPases and the actin cytoskeleton, and that the actin-binding activity of IQGAP1 is regulated by calmodulin.

scholarly journals Cooperative Regulation of Extracellular Signal-Regulated Kinase Activation and Cell Shape Change by Filamin A and β-Arrestins

2006 ◽  
Vol 26 (9) ◽  
pp. 3432-3445 ◽  
Author(s):  
Mark G. H. Scott ◽  
Vincenzo Pierotti ◽  
Hélène Storez ◽  
Erika Lindberg ◽  
Alain Thuret ◽  
...  
Keyword(s):  
Shape Change ◽  
Receptor Activation ◽  
Dominant Negative ◽  
Scaffolding Protein ◽  
Actin Binding ◽  
Filamin A ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal

ABSTRACT β-Arrestins (βarr) are multifunctional adaptor proteins that can act as scaffolds for G protein-coupled receptor activation of mitogen-activated protein kinases (MAPK). Here, we identify the actin-binding and scaffolding protein filamin A (FLNA) as a βarr-binding partner using Son of sevenless recruitment system screening, a classical yeast two-hybrid system, coimmunoprecipitation analyses, and direct binding in vitro. In FLNA, the βarr-binding site involves tandem repeat 22 in the carboxyl terminus. βarr binds FLNA through both its N- and C-terminal domains, indicating the presence of multiple binding sites. We demonstrate that βarr and FLNA act cooperatively to activate the MAPK extracellular signal-regulated kinase (ERK) downstream of activated muscarinic M1 (M1MR) and angiotensin II type 1a (AT1AR) receptors and provide experimental evidence indicating that this phenomenon is due to the facilitation of βarr-ERK2 complex formation by FLNA. In Hep2 cells, stimulation of M1MR or AT1AR results in the colocalization of receptor, βarr, FLNA, and active ERK in membrane ruffles. Reduction of endogenous levels of βarr or FLNA and a catalytically inactive dominant negative MEK1, which prevents ERK activation, inhibit membrane ruffle formation, indicating the functional requirement for βarr, FLNA, and active ERK in this process. Our results indicate that βarr and FLNA cooperate to regulate ERK activation and actin cytoskeleton reorganization.

scholarly journals Adapter Protein SH2B1β Binds Filamin A to Regulate Prolactin-Dependent Cytoskeletal Reorganization and Cell Motility

2011 ◽  
Vol 25 (7) ◽  
pp. 1231-1243 ◽  
Author(s):  
Leah Rider ◽  
Maria Diakonova
Keyword(s):  
Actin Cytoskeleton ◽  
Cell Motility ◽  
Binding Protein ◽  
Sh2 Domain ◽  
Actin Binding ◽  
Adapter Protein ◽  
Deficient Mutant ◽  
Filamin A ◽  
Actin Binding Protein ◽  
Dependent Cell

Abstract Prolactin (PRL) regulates cytoskeletal rearrangement and cell motility. PRL-activated Janus tyrosine kinase 2 (JAK2) phosphorylates the p21-activated serine-threonine kinase (PAK)1 and the Src homology 2 (SH2) domain-containing adapter protein SH2B1β. SH2B1β is an actin-binding protein that cross-links actin filaments, whereas PAK1 regulates the actin cytoskeleton by different mechanisms, including direct phosphorylation of the actin-binding protein filamin A (FLNa). Here, we have used a FLNa-deficient human melanoma cell line (M2) and its derivative line (A7) that stably expresses FLNa to demonstrate that SH2B1β and FLNa are required for maximal PRL-dependent cell ruffling. We have found that in addition to two actin-binding domains, SH2B1β has a FLNa-binding domain (amino acids 200–260) that binds directly to repeats 17–23 of FLNa. The SH2B1β-FLNa interaction participates in PRL-dependent actin rearrangement. We also show that phosphorylation of the three tyrosines of PAK1 by JAK2, as well as the presence of FLNa, play a role in PRL-dependent cell ruffling. Finally, we show that the actin- and FLNa-binding-deficient mutant of SH2B1β (SH2B1β 3Δ) abolished PRL-dependent ruffling and PRL-dependent cell migration when expressed along with PAK1 Y3F (JAK2 tyrosyl-phosphorylation-deficient mutant). Together, these data provide insight into a novel mechanism of PRL-stimulated regulation of the actin cytoskeleton and cell motility via JAK2 signaling through FLNa, PAK1, and SH2B1β. We propose a model for PRL-dependent regulation of the actin cytoskeleton that integrates our findings with previous studies.

scholarly journals The Saccharomyces cerevisiae Calponin/Transgelin Homolog Scp1 Functions with Fimbrin to Regulate Stability and Organization of the Actin Cytoskeleton

2003 ◽  
Vol 14 (7) ◽  
pp. 2617-2629 ◽  
Author(s):  
Anya Goodman ◽  
Bruce L. Goode ◽  
Paul Matsudaira ◽  
Gerald R. Fink
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Binding ◽  
Filamentous Actin ◽  
Cortical Actin ◽  
Associated Proteins ◽  
Cross Links ◽  
Biochemical Analyses ◽  
Actin Patch ◽  
The One

Calponins and transgelins are members of a conserved family of actin-associated proteins widely expressed from yeast to humans. Although a role for calponin in muscle cells has been described, the biochemical activities and in vivo functions of nonmuscle calponins and transgelins are largely unknown. Herein, we have used genetic and biochemical analyses to characterize the budding yeast member of this family, Scp1, which most closely resembles transgelin and contains one calponin homology (CH) domain. We show that Scp1 is a novel component of yeast cortical actin patches and shares in vivo functions and biochemical activities with Sac6/fimbrin, the one other actin patch component that contains CH domains. Purified Scp1 binds directly to filamentous actin, cross-links actin filaments, and stabilizes filaments against disassembly. Sequences in Scp1 sufficient for actin binding and cross-linking reside in its carboxy terminus, outside the CH domain. Overexpression of SCP1 suppresses sac6Δ defects, and deletion of SCP1 enhances sac6Δ defects. Together, these data show that Scp1 and Sac6/fimbrin cooperate to stabilize and organize the yeast actin cytoskeleton.

Hypoxia-induced interaction of filamin with Drp1 causes mitochondrial hyperfission–associated myocardial senescence

2018 ◽  
Vol 11 (556) ◽  
pp. eaat5185 ◽  
Author(s):  
Akiyuki Nishimura ◽  
Tsukasa Shimauchi ◽  
Tomohiro Tanaka ◽  
Kakeru Shimoda ◽  
Takashi Toyama ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Actin Binding ◽  
Dependent Manner ◽  
Filamin A ◽  
Nucleotide Exchange ◽  
Rat Cardiomyocytes ◽  
Nucleotide Exchange Factor ◽  
Starting Point

Defective mitochondrial dynamics through aberrant interactions between mitochondria and actin cytoskeleton is increasingly recognized as a key determinant of cardiac fragility after myocardial infarction (MI). Dynamin-related protein 1 (Drp1), a mitochondrial fission–accelerating factor, is activated locally at the fission site through interactions with actin. Here, we report that the actin-binding protein filamin A acted as a guanine nucleotide exchange factor for Drp1 and mediated mitochondrial fission–associated myocardial senescence in mice after MI. In peri-infarct regions characterized by mitochondrial hyperfission and associated with myocardial senescence, filamin A colocalized with Drp1 around mitochondria. Hypoxic stress induced the interaction of filamin A with the GTPase domain of Drp1 and increased Drp1 activity in an actin-binding–dependent manner in rat cardiomyocytes. Expression of the A1545T filamin mutant, which potentiates actin aggregation, promoted mitochondrial hyperfission under normoxia. Furthermore, pharmacological perturbation of the Drp1–filamin A interaction by cilnidipine suppressed mitochondrial hyperfission–associated myocardial senescence and heart failure after MI. Together, these data demonstrate that Drp1 association with filamin and the actin cytoskeleton contributes to cardiac fragility after MI and suggests a potential repurposing of cilnidipine, as well as provides a starting point for innovative Drp1 inhibitor development.

scholarly journals Genetic interaction between profilin and myosin II reveals a potential role for myosin II in actin filament disassembly in vivo

2020 ◽  
Author(s):  
Paola Zambon ◽  
Saravanan Palani ◽  
Shekhar Sanjay Jadhav ◽  
Pananghat Gayathri ◽  
Mohan K. Balasubramanian
Keyword(s):  
Actin Cytoskeleton ◽  
Genetic Interaction ◽  
Myosin Ii ◽  
Eukaryotic Cell ◽  
Actin Binding ◽  
Cell Physiology ◽  
Physical Interaction ◽  
Actin Cable ◽  
And Migration

AbstractThe actin cytoskeleton plays a variety of roles in eukaryotic cell physiology, ranging from cell polarity and migration to cytokinesis. Key to the function of the actin cytoskeleton is the mechanisms that control its assembly, stability, and turnover. Through genetic analyses in fission yeast, we found that, myo2-S1 (myo2-G515D), a myosin II mutant allele was capable of rescuing lethality caused by compromise of mechanisms involved in actin cable / ring assembly and stability. The mutation in myo2-S1 affects the activation loop of Myosin II, which is involved in physical interaction with subdomain 1 of actin and in stimulating the ATPase activity of Myosin. Consistently, actomyosin rings in myo2-S1 cell ghosts were severely compromised in contraction upon ATP addition, suggesting that Myo2-S1p was defective in actin binding and / or motor activity. These studies strongly suggest a role for Myo2p in actin cytoskeletal disassembly and turnover, and that compromise of this activity leads to genetic suppression of mutants defective in actin cable assembly / stability.

scholarly journals RNase L Interacts with Filamin A To Regulate Actin Dynamics and Barrier Function for Viral Entry

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Krishnamurthy Malathi ◽  
Mohammad Adnan Siddiqui ◽  
Shubham Dayal ◽  
Merna Naji ◽  
Heather J. Ezelle ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Viral Entry ◽  
Virus Entry ◽  
Innate Immune ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Rnase L ◽  
Filamin A ◽  
Antiviral Signaling ◽  
Effector Functions

ABSTRACTThe actin cytoskeleton and its network of associated proteins constitute a physical barrier that viruses must circumvent to gain entry into cells for productive infection. The mechanisms by which the physical signals of infection are sensed by the host to activate an innate immune response are not well understood. The antiviral endoribonuclease RNase L is ubiquitously expressed in a latent form and activated upon binding 2-5A, a unique oligoadenylate produced during viral infections. We provide evidence that RNase L in its inactive form interacts with the actin-binding protein Filamin A to modulate the actin cytoskeleton and inhibit virus entry. Cells lacking either RNase L or Filamin A displayed increased virus entry which was exacerbated in cells lacking both proteins. RNase L deletion mutants that reduced Filamin A interaction displayed a compromised ability to restrict virus entry, supporting the idea of an important role for the RNase L-Filamin A complex in barrier function. Remarkably, both the wild type and a catalytically inactive RNase L mutant were competent to reduce virus entry when transfected into RNase L-deficient cells, indicating that this novel function of RNase L is independent of its enzymatic activity. Virus infection and RNase L activation disrupt its association with Filamin A and release RNase L to mediate its canonical nuclease-dependent antiviral activities. The dual functions of RNase L as a constitutive component of the actin cytoskeleton and as an induced mediator of antiviral signaling and effector functions provide insights into its mechanisms of antiviral activity and opportunities for the development of novel antiviral agents.IMPORTANCECells constantly face and sample pathogens on their outer surface. The actin cytoskeleton and interacting proteins associate with the cell membrane and constitute a barrier to infection. Disruption of the actin cytoskeleton allows viruses to enter the cell and induces innate immune responses to clear infections. The molecular mechanisms that link virus-induced physical perturbations to host defense pathways remain unclear. Our studies identified a novel interaction between the antiviral endoribonuclease RNase L and the actin-binding protein Filamin A that enhances host defense by preventing viral entry into naive cells. This role for RNase L is independent of its enzymatic function. Virus infection alters actin dynamics, disrupts the RNase L-Filamin A complex, and releases RNase L to mediate antiviral signaling and effector functions via its established nucleolytic activities. These dual roles for RNase L provide an efficient strategy to protect cells from infection and rapidly respond upon pathogen exposure.

Abstract 732: The P2Y 2 Receptor Selectively Binds to Filamin A to Regulate Spreading and Migration of Vascular Smooth Muscle Cells

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Ningpu Yu ◽  
Gerardo E Fernandez ◽  
Gary A Weisman ◽  
Cheikh I Seye
Keyword(s):  
Smooth Muscle ◽  
Cell Migration ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Actin Cytoskeleton ◽  
Vascular Smooth Muscle Cells ◽  
Filamin A ◽  
Wild Type ◽  
Adenoviral Infection ◽  
And Migration

The functional expression of the G protein-coupled P2Y 2 nucleotide receptor has been associated with the development of intimal lesions. Activation of this receptor also stimulates actin cytoskeleton reorganization and migration of vascular smooth muscle cells (SMCs). Since cell migration has been linked to the dynamic reorganization of the actin cytoskeleton, which transmits biochemical signals and forces necessary for cell locomotion, the aim of the present study was to identify cytoskeletal proteins that bind to the P2Y 2 receptor and potentially regulate SMC migration. Using the yeast two-hybrid system, we isolated filamin A, a filamentous actin-cross linking protein that interacts with the C-terminal domain of the P2Y 2 receptor and we used deletion mapping to identify amino acid deletion in the P2Y 2 receptor that led to selective loss of filamin A binding. Ex-vivo treatment of aortic explants with the P2Y 2 receptor agonist UTP (10 μmol/L) significantly promoted migration of SMCs in wild type but not in P2Y 2 receptor −/− mice. Likewise, using a Transwell migration assay we showed that UTP increased migration of SMCs in wild type (3.5 folds, P<0.01 vs. untreated cells) but not P2Y 2 receptor −/− mice (P<0.4 vs. untreated cells). Adenoviral infection of the full length P2Y 2 receptor restored UTP-mediated cell migration in P2Y 2 receptor −/− mice whereas infection of a mutant P2Y 2 receptor that does not bind filamin A did not. UTP-induced migration was preceded by a rapid phosphorylation of filamin A that was not observed either in P2Y 2 receptor −/− SMCs or in P2Y 2 receptor −/− SMCs infected with the mutant P2Y 2 receptor that does not bind filamin A. Treatment of SMCs from wild type mice with UTP (10 μmol/L) caused a 4-fold increase in spreading to collagen I as compared to unstimulated cells. The UTP-mediated increase of SMC spreading was not found in P2Y 2 receptor −/− SMCs but was restored by adenoviral infection of the full length P2Y 2 receptor cDNA into these cells. However, adenoviral delivery of a mutant receptor −/− which does not bind to filamin A did not restore UTP-mediated spreading of P2Y 2 receptor SMCs to collagen. This study demonstrates that P2Y 2 -dependent modulation of the actin cytoskeleton selectively regulates spreading and migration of SMC.

scholarly journals Filamin, a synaptic organizer in Drosophila, determines glutamate receptor composition and membrane growth

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
GaYoung Lee ◽  
Thomas L Schwarz
Keyword(s):  
Glutamate Receptor ◽  
Synapse Formation ◽  
Morphological Plasticity ◽  
Postsynaptic Membrane ◽  
Scaffolding Protein ◽  
Actin Binding ◽  
Filamin A ◽  
Biochemical Analyses ◽  
Receptor Clusters ◽  
Larval Neuromuscular Junction

Filamin is a scaffolding protein that functions in many cells as an actin-crosslinker. FLN90, an isoform of the Drosophila ortholog Filamin/cheerio that lacks the actin-binding domain, is here shown to govern the growth of postsynaptic membrane folds and the composition of glutamate receptor clusters at the larval neuromuscular junction. Genetic and biochemical analyses revealed that FLN90 is present surrounding synaptic boutons. FLN90 is required in the muscle for localization of the kinase dPak and, downstream of dPak, for localization of the GTPase Ral and the exocyst complex to this region. Consequently, Filamin is needed for growth of the subsynaptic reticulum. In addition, in the absence of filamin, type-A glutamate receptor subunits are lacking at the postsynapse, while type-B subunits cluster correctly. Receptor composition is dependent on dPak, but independent of the Ral pathway. Thus two major aspects of synapse formation, morphological plasticity and subtype-specific receptor clustering, require postsynaptic Filamin.

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