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Fisher LAB, Carriquí-Madroñal B, Mulder T, Huelsmann S, Schöck F, González-Morales N. Filamin protects myofibrils from contractile damage through changes in its mechanosensory region. PLoS Genet 2024; 20:e1011101. [PMID: 38905299 PMCID: PMC11221683 DOI: 10.1371/journal.pgen.1011101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 07/03/2024] [Accepted: 06/07/2024] [Indexed: 06/23/2024] Open
Abstract
Filamins are mechanosensitive actin crosslinking proteins that organize the actin cytoskeleton in a variety of shapes and tissues. In muscles, filamin crosslinks actin filaments from opposing sarcomeres, the smallest contractile units of muscles. This happens at the Z-disc, the actin-organizing center of sarcomeres. In flies and vertebrates, filamin mutations lead to fragile muscles that appear ruptured, suggesting filamin helps counteract muscle rupturing during muscle contractions by providing elastic support and/or through signaling. An elastic region at the C-terminus of filamin is called the mechanosensitive region and has been proposed to sense and counteract contractile damage. Here we use molecularly defined mutants and microscopy analysis of the Drosophila indirect flight muscles to investigate the molecular details by which filamin provides cohesion to the Z-disc. We made novel filamin mutations affecting the C-terminal region to interrogate the mechanosensitive region and detected three Z-disc phenotypes: dissociation of actin filaments, Z-disc rupture, and Z-disc enlargement. We tested a constitutively closed filamin mutant, which prevents the elastic changes in the mechanosensitive region and results in ruptured Z-discs, and a constitutively open mutant which has the opposite elastic effect on the mechanosensitive region and gives rise to enlarged Z-discs. Finally, we show that muscle contraction is required for Z-disc rupture. We propose that filamin senses myofibril damage by elastic changes in its mechanosensory region, stabilizes the Z-disc, and counteracts contractile damage at the Z-disc.
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Affiliation(s)
| | | | - Tiara Mulder
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Sven Huelsmann
- Interfaculty Institute of Cell Biology, Universität Tübingen, Tübingen, Germany
| | - Frieder Schöck
- Department of Biology, McGill University, Montreal, Quebec, Canada
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2
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Deng Y, Yan J. Force-Dependent Structural Changes of Filamin C Rod Domains Regulated by Filamin C Dimer. J Am Chem Soc 2023; 145:14670-14678. [PMID: 37369984 PMCID: PMC10348313 DOI: 10.1021/jacs.3c02303] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Indexed: 06/29/2023]
Abstract
Filamin C (FLNC), a large dimeric actin-binding protein in muscle cells, plays a critical role in transmitting force in the cytoskeleton and that between membrane receptors and the cytoskeleton. It performs crucial mechanosensing and downstream mechanotransduction functions via force-dependent interactions with signaling proteins. Mutations in FLNC have been linked to muscle and heart diseases. The mechanical responses of the force-bearing elements in FLNC have not been determined. This study investigated the mechanical responses of FLNC domains and their dimerization interface using magnetic tweezers. Results showed high stability of the N-terminal domains in the rod-1 segment but significant changes in the rod-2 domains in response to forces of a few piconewtons (pN). The dimerization interface, formed by the R24 domain, has a lifetime of seconds to tens of seconds at pN forces, and it dissociates within 1 s at forces greater than 14 pN. The findings suggest the FLNC dimerization interface provides sufficient mechanical stability that enables force-dependent structural changes in rod-2 domains for signaling protein binding and maintains structural integrity of the rod-1 domains.
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Affiliation(s)
- Yunxin Deng
- Mechanobiology
Institute, National University of Singapore, Singapore 117411, Singapore
| | - Jie Yan
- Mechanobiology
Institute, National University of Singapore, Singapore 117411, Singapore
- Department
of Physics, National University of Singapore, Singapore 117542, Singapore
- Joint
School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
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3
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Jain M, Weber A, Maly K, Manjaly G, Deek J, Tsvyetkova O, Stulić M, Toca‐Herrera JL, Jantsch MF. A-to-I RNA editing of Filamin A regulates cellular adhesion, migration and mechanical properties. FEBS J 2022; 289:4580-4601. [PMID: 35124883 PMCID: PMC9546289 DOI: 10.1111/febs.16391] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 12/23/2021] [Accepted: 02/04/2022] [Indexed: 02/06/2023]
Abstract
A-to-I RNA editing by ADARs is an abundant epitranscriptomic RNA-modification in metazoa. In mammals, Flna pre-mRNA harbours a single conserved A-to-I RNA editing site that introduces a Q-to-R amino acid change in Ig repeat 22 of the encoded protein. Previously, we showed that FLNA editing regulates smooth muscle contraction in the cardiovascular system and affects cardiac health. The present study investigates how ADAR2-mediated A-to-I RNA editing of Flna affects actin crosslinking, cell mechanics, cellular adhesion and cell migration. Cellular assays and AFM measurements demonstrate that the edited version of FLNA increases cellular stiffness and adhesion but impairs cell migration in both, mouse fibroblasts and human tumour cells. In vitro, edited FLNA leads to increased actin crosslinking, forming actin gels of higher stress resistance. Our study shows that Flna RNA editing is a novel regulator of cytoskeletal organisation, affecting the mechanical property and mechanotransduction of cells.
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Affiliation(s)
- Mamta Jain
- Division of Cell BiologyCenter for Anatomy and Cell BiologyMedical University of ViennaAustria
| | - Andreas Weber
- Department of NanobiotechnologyInstitute for BiophysicsUniversity of Natural Resources and Life Sciences Vienna (BOKU)Austria
| | - Kathrin Maly
- Division of Cell BiologyCenter for Anatomy and Cell BiologyMedical University of ViennaAustria
| | - Greeshma Manjaly
- Division of Cell BiologyCenter for Anatomy and Cell BiologyMedical University of ViennaAustria
| | - Joanna Deek
- Department of Physics, Cellular Biophysics E27Technical University of MunichGarchingGermany
| | - Olena Tsvyetkova
- Division of Cell BiologyCenter for Anatomy and Cell BiologyMedical University of ViennaAustria
| | - Maja Stulić
- Division of Cell BiologyCenter for Anatomy and Cell BiologyMedical University of ViennaAustria
| | - José L. Toca‐Herrera
- Department of NanobiotechnologyInstitute for BiophysicsUniversity of Natural Resources and Life Sciences Vienna (BOKU)Austria
| | - Michael F. Jantsch
- Division of Cell BiologyCenter for Anatomy and Cell BiologyMedical University of ViennaAustria
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4
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Vakhrusheva A, Murashko A, Trifonova E, Efremov Y, Timashev P, Sokolova O. Role of Actin-binding Proteins in the Regulation of Cellular Mechanics. Eur J Cell Biol 2022; 101:151241. [DOI: 10.1016/j.ejcb.2022.151241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 04/18/2022] [Accepted: 05/19/2022] [Indexed: 12/25/2022] Open
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5
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Lohanadan K, Molt S, Dierck F, van der Ven PFM, Frey N, Höhfeld J, Fürst DO. Isoform-specific functions of synaptopodin-2 variants in cytoskeleton stabilization and autophagy regulation in muscle under mechanical stress. Exp Cell Res 2021; 408:112865. [PMID: 34637763 DOI: 10.1016/j.yexcr.2021.112865] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 10/01/2021] [Accepted: 10/03/2021] [Indexed: 11/17/2022]
Abstract
Protein homeostasis (proteostasis) in multicellular organisms depends on the maintenance of force-bearing and force-generating cellular structures. Within myofibrillar Z-discs of striated muscle, isoforms of synaptopodin-2 (SYNPO2/myopodin) act as adapter proteins that are engaged in proteostasis of the actin-crosslinking protein filamin C (FLNc) under mechanical stress. SYNPO2 directly binds F-actin, FLNc and α-actinin and thus contributes to the architectural features of the actin cytoskeleton. By its association with autophagy mediating proteins, i.e. BAG3 and VPS18, SYNPO2 is also engaged in protein quality control and helps to target mechanical unfolded and damaged FLNc for degradation. Here we show that deficiency of all SYNPO2-isoforms in myotubes leads to decreased myofibrillar stability and deregulated autophagy under mechanical stress. In addition, isoform-specific proteostasis functions were revealed. The PDZ-domain containing variant SYNPO2b and the shorter, PDZ-less isoform SYNPO2e both localize to Z-discs. Yet, SYNPO2e is less stably associated with the Z-disc than SYNPO2b, and is dynamically transferred into FLNc-containing myofibrillar lesions under mechanical stress. SYNPO2e also recruits BAG3 into these lesions via interaction with the WW domain of BAG3. Our data provide evidence for a role of myofibrillar lesions as a transient quality control compartment essential to prevent and repair contraction-induced myofibril damage in muscle and indicate an important coordinating activity for SYNPO2 therein.
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Affiliation(s)
- Keerthika Lohanadan
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Sibylle Molt
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Franziska Dierck
- Department of Internal Medicine III, University Medical Center Schleswig-Holstein, Campus Kiel, 24105 Kiel, Germany
| | - Peter F M van der Ven
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Norbert Frey
- Department of Internal Medicine III, University Medical Center Schleswig-Holstein, Campus Kiel, 24105 Kiel, Germany; German Centre for Cardiovascular Research, Partner Site Heidelberg, 69120 Heidelberg, Germany
| | - Jörg Höhfeld
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Dieter O Fürst
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany.
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Sengupta A, Rognoni LE, Merkel U, Žoldák G, Rief M. SlyD Accelerates trans-to- cis Prolyl Isomerization in a Mechanosignaling Protein under Load. J Phys Chem B 2021; 125:8712-8721. [PMID: 34279937 DOI: 10.1021/acs.jpcb.1c03648] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Prolyl isomerization is recognized as one of the key regulatory mechanisms, which plays a crucial role in cell signaling, ion channel gating, phage virus infection, and molecular timing. This isomerization is usually slow but often accelerated by an enzyme, called peptidyl-prolyl isomerase (PPIase). In the current project, we investigate using single-molecule force spectroscopy (SMFS) the impact of a bacterial PPIase, SlyD, on the cis-trans isomerization of the proline 2225 (P2225) in an isolated 20th domain of a cytoskeletal mechanosensing protein filamin-A (FlnA20). To explore the FlnA20-PPIase interaction, we have used multiple SMFS modes, like constant velocity, constant distance, and jumping trap experiments. In our previous study, we reported the unique nature of the P2225, which is conserved in all naturally occurring filamins and can slowly (minutes) interconvert between cis-trans isomers, in absence of any PPIase. Our current results show a staggering 25-fold acceleration of the trans-to-cis isomerization rate in the presence of saturating SlyD concentration (7.25 μM) compared to the unenzymatic condition. A SlyD concentration-dependent depletion of the trans isomeric lifetime was also observed. Additionally, we observed that SlyD stabilizes the cis-isomer in the native state of FlnA20 by ∼2 kBT. This is the first single-molecule observation of the cis-trans isomerization catalysis by a PPIase in a mechanosensing protein.
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Affiliation(s)
- Abhigyan Sengupta
- Technische Universität München, Physik Department, Center for Functional Protein Assemblies (CPA), Ernst-Otto-Fischer-Str. 8, D-85748 Garching, Germany
| | - Lorenz E Rognoni
- Technische Universität München, Physik Department, Center for Functional Protein Assemblies (CPA), Ernst-Otto-Fischer-Str. 8, D-85748 Garching, Germany
| | - Ulrich Merkel
- Technische Universität München, Physik Department, Center for Functional Protein Assemblies (CPA), Ernst-Otto-Fischer-Str. 8, D-85748 Garching, Germany
| | - Gabriel Žoldák
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, P.J. Šafárik University, Trieda SNP 1, 040 11Košice, Slovakia
| | - Matthias Rief
- Technische Universität München, Physik Department, Center for Functional Protein Assemblies (CPA), Ernst-Otto-Fischer-Str. 8, D-85748 Garching, Germany
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7
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Zhou J, Kang X, An H, Lv Y, Liu X. The function and pathogenic mechanism of filamin A. Gene 2021; 784:145575. [PMID: 33737122 DOI: 10.1016/j.gene.2021.145575] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 12/13/2022]
Abstract
Filamin A(FLNa) is an actin-binding protein, which participates in the formation of the cytoskeleton, anchors a variety of proteins in the cytoskeleton and regulates cell adhesion and migration. It is involved in signal transduction, cell proliferation and differentiation, pseudopodia formation, vesicle transport, tumor resistance and genetic diseases by binding with interacting proteins. In order to fully elucidate the structure, function and pathogenesis of FLNa, we summarized all substances which directly or indirectly act on FLNa so far, upstream and downstream targets which having effect on it, signaling pathways and their functions. It also recorded the expression and effect of FLNa in different diseases, including hereditary disease and tumors.
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Affiliation(s)
- Jie Zhou
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Xinmei Kang
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Hanxiang An
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Yun Lv
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Xin Liu
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
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8
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Iqbal NS, Jascur TA, Harrison SM, Edwards AB, Smith LT, Choi ES, Arevalo MK, Chen C, Zhang S, Kern AJ, Scheuerle AE, Sanchez EJ, Xing C, Baker LA. Prune belly syndrome in surviving males can be caused by Hemizygous missense mutations in the X-linked Filamin A gene. BMC MEDICAL GENETICS 2020; 21:38. [PMID: 32085749 PMCID: PMC7035669 DOI: 10.1186/s12881-020-0973-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 02/12/2020] [Indexed: 12/12/2022]
Abstract
Background Prune belly syndrome (PBS) is a rare, multi-system congenital myopathy primarily affecting males that is poorly described genetically. Phenotypically, its morbidity spans from mild to lethal, however, all isolated PBS cases manifest three cardinal pathological features: 1) wrinkled flaccid ventral abdominal wall with skeletal muscle deficiency, 2) urinary tract dilation with poorly contractile smooth muscle, and 3) intra-abdominal undescended testes. Despite evidence for a genetic basis, previously reported PBS autosomal candidate genes only account for one consanguineous family and single cases. Methods We performed whole exome sequencing (WES) of two maternal adult half-brothers with syndromic PBS (PBS + Otopalatodigital spectrum disorder [OPDSD]) and two unrelated sporadic individuals with isolated PBS and further functionally validated the identified mutations. Results We identified three unreported hemizygous missense point mutations in the X-chromosome gene Filamin A (FLNA) (c.4952 C > T (p.A1448V), c.6727C > T (p.C2160R), c.5966 G > A (p.G2236E)) in two related cases and two unrelated sporadic individuals. Two of the three PBS mutations map to the highly regulatory, stretch-sensing Ig19–21 region of FLNA and enhance binding to intracellular tails of the transmembrane receptor β-integrin 1 (ITGβ1). Conclusions FLNA is a regulatory actin-crosslinking protein that functions in smooth muscle cells as a mechanosensing molecular scaffold, transmitting force signals from the actin-myosin motor units and cytoskeleton via binding partners to the extracellular matrix. This is the first evidence for an X-linked cause of PBS in multiple unrelated individuals and expands the phenotypic spectrum associated with FLNA in males surviving even into adulthood.
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Affiliation(s)
- Nida S Iqbal
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.
| | - Thomas A Jascur
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Steven M Harrison
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Angelena B Edwards
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Luke T Smith
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Erin S Choi
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Michelle K Arevalo
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Catherine Chen
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Shaohua Zhang
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Adam J Kern
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Angela E Scheuerle
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.,McDermott Center for Human Growth and Development, Department of Bioinformatics, Department of Clinical Sciences, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Emma J Sanchez
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.,Children's Health Dallas, 2350 N. Stemmons Freeway, Suite F4300, Dallas, TX, 75207, USA
| | - Chao Xing
- McDermott Center for Human Growth and Development, Department of Bioinformatics, Department of Clinical Sciences, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Linda A Baker
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA. .,Children's Health Dallas, 2350 N. Stemmons Freeway, Suite F4300, Dallas, TX, 75207, USA.
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9
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The Host Scaffolding Protein Filamin A and the Exocyst Complex Control Exocytosis during InlB-Mediated Entry of Listeria monocytogenes. Infect Immun 2018; 87:IAI.00689-18. [PMID: 30348826 DOI: 10.1128/iai.00689-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 10/16/2018] [Indexed: 02/06/2023] Open
Abstract
Listeria monocytogenes is a foodborne bacterium that causes gastroenteritis, meningitis, or abortion. Listeria induces its internalization (entry) into some human cells through interaction of the bacterial surface protein InlB with its host receptor, the Met tyrosine kinase. InlB and Met promote entry, in part, through stimulation of localized exocytosis. How exocytosis is upregulated during entry is not understood. Here, we show that the human signaling proteins mTOR, protein kinase C-α (PKC-α), and RalA promote exocytosis during entry by controlling the scaffolding protein Filamin A (FlnA). InlB-mediated uptake was accompanied by PKC-α-dependent phosphorylation of serine 2152 in FlnA. Depletion of FlnA by RNA interference (RNAi) or expression of a mutated FlnA protein defective in phosphorylation impaired InlB-dependent internalization. These findings indicate that phosphorylation of FlnA by PKC-α contributes to entry. mTOR and RalA were found to mediate the recruitment of FlnA to sites of InlB-mediated entry. Depletion of PKC-α, mTOR, or FlnA each reduced exocytosis during InlB-mediated uptake. Because the exocyst complex is known to mediate polarized exocytosis, we examined if PKC-α, mTOR, RalA, or FlnA affects this complex. Depletion of PKC-α, mTOR, RalA, or FlnA impaired recruitment of the exocyst component Exo70 to sites of InlB-mediated entry. Experiments involving knockdown of Exo70 or other exocyst proteins demonstrated an important role for the exocyst complex in uptake of Listeria Collectively, our results indicate that PKC-α, mTOR, RalA, and FlnA comprise a signaling pathway that mobilizes the exocyst complex to promote infection by Listeria.
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10
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Haataja TJK, Bernardi RC, Lecointe S, Capoulade R, Merot J, Pentikäinen U. Non-syndromic Mitral Valve Dysplasia Mutation Changes the Force Resilience and Interaction of Human Filamin A. Structure 2018; 27:102-112.e4. [PMID: 30344108 DOI: 10.1016/j.str.2018.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/24/2018] [Accepted: 09/18/2018] [Indexed: 01/03/2023]
Abstract
Filamin A (FLNa), expressed in endocardial endothelia during fetal valve morphogenesis, is key in cardiac development. Missense mutations in FLNa cause non-syndromic mitral valve dysplasia (FLNA-MVD). Here, we aimed to reveal the currently unknown underlying molecular mechanism behind FLNA-MVD caused by the FLNa P637Q mutation. The solved crystal structure of the FLNa3-5 P637Q revealed that this mutation causes only minor structural changes close to mutation site. These changes were observed to significantly affect FLNa's ability to transmit cellular force and to interact with its binding partner. The performed steered molecular dynamics simulations showed that significantly lower forces are needed to split domains 4 and 5 in FLNA-MVD than with wild-type FLNa. The P637Q mutation was also observed to interfere with FLNa's interactions with the protein tyrosine phosphatase PTPN12. Our results provide a crucial step toward understanding the molecular bases behind FLNA-MVD, which is critical for the development of drug-based therapeutics.
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Affiliation(s)
- Tatu J K Haataja
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, 40014 Jyväskylä, Finland
| | - Rafael C Bernardi
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Simon Lecointe
- L'institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes, France
| | | | - Jean Merot
- L'institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes, France
| | - Ulla Pentikäinen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, 40014 Jyväskylä, Finland; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Institute of Biomedicine, University of Turku, 20520 Turku, Finland; Turku Centre for Biotechnology, University of Turku, 20520 Turku, Finland.
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11
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Baudier J, Jenkins ZA, Robertson SP. The filamin-B–refilin axis – spatiotemporal regulators of the actin-cytoskeleton in development and disease. J Cell Sci 2018; 131:131/8/jcs213959. [DOI: 10.1242/jcs.213959] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
ABSTRACT
During development, cycles of spatiotemporal remodeling of higher-order networks of actin filaments contribute to control cell fate specification and differentiation. Programs for controlling these dynamics are hard-wired into actin-regulatory proteins. The filamin family of actin-binding proteins exert crucial mechanotransduction and signaling functions in tissue morphogenesis. Filamin-B (FLNB) is a key player in chondrocyte progenitor differentiation for endochondral ossification. Biallelic loss-of-function mutations or gain-of-function mutations in FLNB cause two groups of skeletal disorders that can be attributed to either the loss of repressive function on TGF-β signaling or a disruption in mechanosensory properties, respectively. In this Review, we highlight a unique family of vertebrate-specific short-lived filamin-binding proteins, the refilins (refilin-A and refilin-B), that modulate filamin-dependent actin crosslinking properties. Refilins are downstream TGF-β effectors in epithelial cells. Double knockout of both refilin-A and refilin-B in mice results in precocious ossification of some axial skeletal elements, leading to malformations that are similar to those seen in FLNB-deficient mice. Based on these findings, we present a model summarizing the role of refilins in regulating the mechanosensory functions of FLNB during skeletal development. We also discuss the possible contribution of refilins to FLNB-related skeletal pathologies that are associated with gain-of-function mutations.
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Affiliation(s)
- Jacques Baudier
- Aix Marseille Université, CNRS, IBDM, 13284 Marseille Cedex 07, France
- Institut de Biologie du Développement de Marseille-UMR CNRS 7288, Campus de Luminy-Case 907, 13288 Marseille Cedex 9, France
| | - Zandra A. Jenkins
- Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Stephen P. Robertson
- Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
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12
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Shams H, Soheilypour M, Peyro M, Moussavi-Baygi R, Mofrad MRK. Looking "Under the Hood" of Cellular Mechanotransduction with Computational Tools: A Systems Biomechanics Approach across Multiple Scales. ACS Biomater Sci Eng 2017; 3:2712-2726. [PMID: 33418698 DOI: 10.1021/acsbiomaterials.7b00117] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Signal modulation has been developed in living cells throughout evolution to promote utilizing the same machinery for multiple cellular functions. Chemical and mechanical modules of signal transmission and transduction are interconnected and necessary for organ development and growth. However, due to the high complexity of the intercommunication of physical intracellular connections with biochemical pathways, there are many missing details in our overall understanding of mechanotransduction processes, i.e., the process by which mechanical signals are converted to biochemical cascades. Cell-matrix adhesions are mechanically coupled to the nucleus through the cytoskeleton. This modulated and tightly integrated network mediates the transmission of mechanochemical signals from the extracellular matrix to the nucleus. Various experimental and computational techniques have been utilized to understand the basic mechanisms of mechanotransduction, yet many aspects have remained elusive. Recently, in silico experiments have made important contributions to the field of mechanobiology. Herein, computational modeling efforts devoted to understanding integrin-mediated mechanotransduction pathways are reviewed, and an outlook is presented for future directions toward using suitable computational approaches and developing novel techniques for addressing important questions in the field of mechanotransduction.
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Affiliation(s)
- Hengameh Shams
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720-1762, United States
| | - Mohammad Soheilypour
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720-1762, United States
| | - Mohaddeseh Peyro
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720-1762, United States
| | - Ruhollah Moussavi-Baygi
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720-1762, United States
| | - Mohammad R K Mofrad
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720-1762, United States
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13
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Seppälä J, Bernardi RC, Haataja TJK, Hellman M, Pentikäinen OT, Schulten K, Permi P, Ylänne J, Pentikäinen U. Skeletal Dysplasia Mutations Effect on Human Filamins' Structure and Mechanosensing. Sci Rep 2017; 7:4218. [PMID: 28652603 PMCID: PMC5484675 DOI: 10.1038/s41598-017-04441-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 05/16/2017] [Indexed: 01/08/2023] Open
Abstract
Cells' ability to sense mechanical cues in their environment is crucial for fundamental cellular processes, leading defects in mechanosensing to be linked to many diseases. The actin cross-linking protein Filamin has an important role in the conversion of mechanical forces into biochemical signals. Here, we reveal how mutations in Filamin genes known to cause Larsen syndrome and Frontometaphyseal dysplasia can affect the structure and therefore function of Filamin domains 16 and 17. Employing X-ray crystallography, the structure of these domains was first solved for the human Filamin B. The interaction seen between domains 16 and 17 is broken by shear force as revealed by steered molecular dynamics simulations. The effects of skeletal dysplasia associated mutations of the structure and mechanosensing properties of Filamin were studied by combining various experimental and theoretical techniques. The results showed that Larsen syndrome associated mutations destabilize or even unfold domain 17. Interestingly, those Filamin functions that are mediated via domain 17 interactions with other proteins are not necessarily affected as strongly interacting peptide binding to mutated domain 17 induces at least partial domain folding. Mutation associated to Frontometaphyseal dysplasia, in turn, transforms 16-17 fragment from compact to an elongated form destroying the force-regulated domain pair.
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Affiliation(s)
- Jonne Seppälä
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, P.O Box 35, Survontie 9 C, FI-40014, Jyvaskyla, Finland
| | - Rafael C Bernardi
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Champaign, 61801, USA
| | - Tatu J K Haataja
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, P.O Box 35, Survontie 9 C, FI-40014, Jyvaskyla, Finland
| | - Maarit Hellman
- Department of Chemistry, University of Jyvaskyla, P.O Box 35, Survontie 9 C, FI-40014, Jyvaskyla, Finland
| | - Olli T Pentikäinen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, P.O Box 35, Survontie 9 C, FI-40014, Jyvaskyla, Finland
| | - Klaus Schulten
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Champaign, 61801, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Champaign, 61801, USA
| | - Perttu Permi
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, P.O Box 35, Survontie 9 C, FI-40014, Jyvaskyla, Finland
- Department of Chemistry, University of Jyvaskyla, P.O Box 35, Survontie 9 C, FI-40014, Jyvaskyla, Finland
| | - Jari Ylänne
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, P.O Box 35, Survontie 9 C, FI-40014, Jyvaskyla, Finland
| | - Ulla Pentikäinen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, P.O Box 35, Survontie 9 C, FI-40014, Jyvaskyla, Finland.
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14
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Hu X, Margadant FM, Yao M, Sheetz MP. Molecular stretching modulates mechanosensing pathways. Protein Sci 2017; 26:1337-1351. [PMID: 28474792 DOI: 10.1002/pro.3188] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/26/2017] [Accepted: 04/27/2017] [Indexed: 01/21/2023]
Abstract
For individual cells in tissues to create the diverse forms of biological organisms, it is necessary that they must reliably sense and generate the correct forces over the correct distances and directions. There is considerable evidence that the mechanical aspects of the cellular microenvironment provide critical physical parameters to be sensed. How proteins sense forces and cellular geometry to create the correct morphology is not understood in detail but protein unfolding appears to be a major component in force and displacement sensing. Thus, the crystallographic structure of a protein domain provides only a starting point to then analyze what will be the effects of physiological forces through domain unfolding or catch-bond formation. In this review, we will discuss the recent studies of cytoskeletal and adhesion proteins that describe protein domain dynamics. Forces applied to proteins can activate or inhibit enzymes, increase or decrease protein-protein interactions, activate or inhibit protein substrates, induce catch bonds and regulate interactions with membranes or nucleic acids. Further, the dynamics of stretch-relaxation can average forces or movements to reliably regulate morphogenic movements. In the few cases where single molecule mechanics are studied under physiological conditions such as titin and talin, there are rapid cycles of stretch-relaxation that produce mechanosensing signals. Fortunately, the development of new single molecule and super-resolution imaging methods enable the analysis of single molecule mechanics in physiologically relevant conditions. Thus, we feel that stereotypical changes in cell and tissue shape involve mechanosensing that can be analyzed at the nanometer level to determine the molecular mechanisms involved.
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Affiliation(s)
- Xian Hu
- Mechanobiology Institute, National University of Singapore, Singapore, 117411.,Department of Biosciences, University of Oslo, Oslo, 0316, Norway
| | | | - Mingxi Yao
- Mechanobiology Institute, National University of Singapore, Singapore, 117411
| | - Michael Patrick Sheetz
- Mechanobiology Institute, National University of Singapore, Singapore, 117411.,Department of Biological Sciences, University of Columbia, New York, 10027
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15
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Evidence for the mechanosensor function of filamin in tissue development. Sci Rep 2016; 6:32798. [PMID: 27597179 PMCID: PMC5011733 DOI: 10.1038/srep32798] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/15/2016] [Indexed: 12/20/2022] Open
Abstract
Cells integrate mechanical properties of their surroundings to form multicellular, three-dimensional tissues of appropriate size and spatial organisation. Actin cytoskeleton-linked proteins such as talin, vinculin and filamin function as mechanosensors in cells, but it has yet to be tested whether the mechanosensitivity is important for their function in intact tissues. Here we tested, how filamin mechanosensing contributes to oogenesis in Drosophila. Mutations that require more or less force to open the mechanosensor region demonstrate that filamin mechanosensitivity is important for the maturation of actin-rich ring canals that are essential for Drosophila egg development. The open mutant was more tightly bound to the ring canal structure while the closed mutant dissociated more frequently. Thus, our results show that an appropriate level of mechanical sensitivity is required for filamins’ function and dynamics during Drosophila egg growth and support the structure-based model in which the opening and closing of the mechanosensor region regulates filamin binding to cellular components.
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16
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Sato T, Ishii J, Ota Y, Sasaki E, Shibagaki Y, Hattori S. Mammalian target of rapamycin (mTOR) complex 2 regulates filamin A-dependent focal adhesion dynamics and cell migration. Genes Cells 2016; 21:579-93. [DOI: 10.1111/gtc.12366] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 03/01/2016] [Indexed: 12/23/2022]
Affiliation(s)
- Tatsuhiro Sato
- Division of Biochemistry; School of Pharmaceutical Sciences; Kitasato University; 5-9-1 Shirokane Minato-ku Tokyo 108-8641 Japan
| | - Junko Ishii
- Division of Biochemistry; School of Pharmaceutical Sciences; Kitasato University; 5-9-1 Shirokane Minato-ku Tokyo 108-8641 Japan
| | - Yuki Ota
- Division of Biochemistry; School of Pharmaceutical Sciences; Kitasato University; 5-9-1 Shirokane Minato-ku Tokyo 108-8641 Japan
| | - Eri Sasaki
- Division of Biochemistry; School of Pharmaceutical Sciences; Kitasato University; 5-9-1 Shirokane Minato-ku Tokyo 108-8641 Japan
| | - Yoshio Shibagaki
- Division of Biochemistry; School of Pharmaceutical Sciences; Kitasato University; 5-9-1 Shirokane Minato-ku Tokyo 108-8641 Japan
| | - Seisuke Hattori
- Division of Biochemistry; School of Pharmaceutical Sciences; Kitasato University; 5-9-1 Shirokane Minato-ku Tokyo 108-8641 Japan
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17
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Dual functions of Rap1 are crucial for T-cell homeostasis and prevention of spontaneous colitis. Nat Commun 2015; 6:8982. [PMID: 26634692 PMCID: PMC4686857 DOI: 10.1038/ncomms9982] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 10/22/2015] [Indexed: 01/03/2023] Open
Abstract
Rap1-GTP activates leukocyte function-associated antigen-1 (LFA-1) to induce arrest on the high endothelial venule (HEV). Here we show that Rap1-GDP restrains rolling behaviours of T cells on the peripheral lymph node addressin (PNAd), P-selectin and mucosal addressin cell adhesion molecule-1 (MadCAM-1) by inhibiting tether formation. Consequently, Rap1 deficiency impairs homing of naive T cells to peripheral lymph nodes, but accelerates homing of TH17 and TH1 cells to the colon, resulting in spontaneous colitis with tumours. Rap1-GDP associates with and activates lymphocyte-oriented kinase, which phosphorylates ERM (ezrin, radixin and moesin) in resting T cells. Phosphomimetic ezrin reduces the rolling of Rap1-deficient cells, and thereby decreases their homing into the colon. On the other hand, chemokines activate Rap1 at the plasma membrane within seconds, and Rap1-GTP binds to filamins, which diminishes its association with the β2 chain of LFA-1 and results in LFA-1 activation. This Rap1-dependent regulation of T-cell circulation prevents the onset of colitis. Rap1, a member of the Ras family of small guanine triphosphatases, mediates lymphocyte adhesion to high endothelial venules. Here the authors show that depending on its activation status Rap1 plays a dual role in T cell adhesion and by regulating T cell homeostasis is involved in the protection from colitis.
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18
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Seppälä J, Tossavainen H, Rodic N, Permi P, Pentikäinen U, Ylänne J. Flexible Structure of Peptide-Bound Filamin A Mechanosensor Domain Pair 20-21. PLoS One 2015; 10:e0136969. [PMID: 26322797 PMCID: PMC4554727 DOI: 10.1371/journal.pone.0136969] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 08/12/2015] [Indexed: 11/18/2022] Open
Abstract
Filamins (FLNs) are large, multidomain actin cross-linking proteins with diverse functions. Besides regulating the actin cytoskeleton, they serve as important links between the extracellular matrix and the cytoskeleton by binding cell surface receptors, functioning as scaffolds for signaling proteins, and binding several other cytoskeletal proteins that regulate cell adhesion dynamics. Structurally, FLNs are formed of an amino terminal actin-binding domain followed by 24 immunoglobulin-like domains (IgFLNs). Recent studies have demonstrated that myosin-mediated contractile forces can reveal hidden protein binding sites in the domain pairs IgFLNa18–19 and 20–21, enabling FLNs to transduce mechanical signals in cells. The atomic structures of these mechanosensor domain pairs in the resting state are known, as well as the structures of individual IgFLN21 with ligand peptides. However, little experimental data is available on how interacting protein binding deforms the domain pair structures. Here, using small-angle x-ray scattering-based modelling, x-ray crystallography, and NMR, we show that the adaptor protein migfilin-derived peptide-bound structure of IgFLNa20–21 is flexible and adopts distinctive conformations depending on the presence or absence of the interacting peptide. The conformational changes reported here may be common for all peptides and may play a role in the mechanosensor function of the site.
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Affiliation(s)
- Jonne Seppälä
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
- * E-mail:
| | - Helena Tossavainen
- Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Nebojsa Rodic
- Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Perttu Permi
- Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Ulla Pentikäinen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Jari Ylänne
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
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19
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Plaza GR, Uyeda TQP, Mirzaei Z, Simmons CA. Study of the influence of actin-binding proteins using linear analyses of cell deformability. SOFT MATTER 2015; 11:5435-5446. [PMID: 26059185 DOI: 10.1039/c5sm00125k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The actin cytoskeleton plays a key role in the deformability of the cell and in mechanosensing. Here we analyze the contributions of three major actin cross-linking proteins, myosin II, α-actinin and filamin, to cell deformability, by using micropipette aspiration of Dictyostelium cells. We examine the applicability of three simple mechanical models: for small deformation, linear viscoelasticity and drop of liquid with a tense cortex; and for large deformation, a Newtonian viscous fluid. For these models, we have derived linearized equations and we provide a novel, straightforward methodology to analyze the experiments. This methodology allowed us to differentiate the effects of the cross-linking proteins in the different regimes of deformation. Our results confirm some previous observations and suggest important relations between the molecular characteristics of the actin-binding proteins and the cell behavior: the effect of myosin is explained in terms of the relation between the lifetime of the bond to actin and the resistive force; the presence of α-actinin obstructs the deformation of the cytoskeleton, presumably mainly due to the higher molecular stiffness and to the lower dissociation rate constants; and filamin contributes critically to the global connectivity of the network, possibly by rapidly turning over cross-links during the remodeling of the cytoskeletal network, thanks to the higher rate constants, flexibility and larger size. The results suggest a sophisticated relationship between the expression levels of actin-binding proteins, deformability and mechanosensing.
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Affiliation(s)
- Gustavo R Plaza
- Departamento de Ciencia de Materiales, ETSI de Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
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20
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Vial D, McKeown-Longo PJ. Role of EGFR expression levels in the regulation of integrin function by EGF. Mol Carcinog 2015; 55:1118-23. [PMID: 26053065 DOI: 10.1002/mc.22346] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 05/05/2015] [Accepted: 05/14/2015] [Indexed: 12/28/2022]
Abstract
Activation of β1 integrins in dormant tumor cells has been linked to metastatic progression, suggesting that therapies designed to maintain β1 integrins in an inactive state may be useful in the prevention of metastatic disease. Our earlier studies have demonstrated that EGF regulates the activation state of the α5β1 integrin in EGFR overexpressing tumor cells through an ERK/p90RSK signaling pathway. Activation of this pathway by EGF resulted in the filamin A dependent inactivation of the α5β1 integrin receptor for fibronectin. The current study was designed to address the role of EGFR overexpression in the regulation of α5β1 integrin activation state by EGF. Lentiviral knockdown of EGFR coupled with limited dilution cloning was used to develop A431 squamous carcinoma cell lines expressing high, moderate, and low levels of EGFR. Inactivation of α5β1 integrin by EGF was shown to correlate with both the level of EGFR expression and the extent of p90RSK phosphorylation, but not with the level of ERK phosphorylation, suggesting that high levels of EGFR promote α5β1 integrin inactivation through sustained activation of p90RSK. Treatment of cells with EGFR kinase inhibitor resulted in a reactivation of the integrin which could be reversed with the phosphatase inhibitor, menadione. Taken together, these findings indicate that p90RSK may function to maintain dormancy in tumor cells expressing high levels of EGFR. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Daniel Vial
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, New York
| | - Paula J McKeown-Longo
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, New York
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21
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Truong T, Shams H, Mofrad MRK. Mechanisms of integrin and filamin binding and their interplay with talin during early focal adhesion formation. Integr Biol (Camb) 2015; 7:1285-96. [DOI: 10.1039/c5ib00133a] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Mechanisms of the interplay among filamin, integrin and talin during early focal adhesion formation were explored using molecular dynamics simulations.
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Affiliation(s)
- Tiffany Truong
- Molecular Cell Biomechanics Laboratory
- Departments of Bioengineering and Mechanical Engineering
- University of California Berkeley
- Berkeley
- USA
| | - Hengameh Shams
- Molecular Cell Biomechanics Laboratory
- Departments of Bioengineering and Mechanical Engineering
- University of California Berkeley
- Berkeley
- USA
| | - Mohammad R. K. Mofrad
- Molecular Cell Biomechanics Laboratory
- Departments of Bioengineering and Mechanical Engineering
- University of California Berkeley
- Berkeley
- USA
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22
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Sethi R, Ylänne J. Small-angle X-ray scattering reveals compact domain-domain interactions in the N-terminal region of filamin C. PLoS One 2014; 9:e107457. [PMID: 25243668 PMCID: PMC4170960 DOI: 10.1371/journal.pone.0107457] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 08/18/2014] [Indexed: 12/30/2022] Open
Abstract
Filamins are multi-domain, actin cross-linking, and scaffolding proteins. In addition to the actin cross-linking function, filamins have a role in mechanosensor signaling. The mechanosensor function is mediated by domain-domain interaction in the C-terminal region of filamins. Recently, we have shown that there is a three-domain interaction module in the N-terminal region of filamins, where the neighboring domains stabilize the structure of the middle domain and thereby regulate its interaction with ligands. In this study, we have used small-angle X-ray scattering as a tool to screen for potential domain-domain interactions in the N-terminal region. We found evidence of four domain-domain interactions with varying flexibility. These results confirm our previous study showing that domains 3, 4, and 5 exist as a compact three domain module. In addition, we report interactions between domains 11-12 and 14-15, which are thus new candidate sites for mechanical regulation.
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Affiliation(s)
- Ritika Sethi
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Jari Ylänne
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
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23
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Molt S, Bührdel JB, Yakovlev S, Schein P, Orfanos Z, Kirfel G, Winter L, Wiche G, van der Ven PFM, Rottbauer W, Just S, Belkin AM, Fürst DO. Aciculin interacts with filamin C and Xin and is essential for myofibril assembly, remodeling and maintenance. J Cell Sci 2014; 127:3578-92. [PMID: 24963132 DOI: 10.1242/jcs.152157] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Filamin C (FLNc) and Xin actin-binding repeat-containing proteins (XIRPs) are multi-adaptor proteins that are mainly expressed in cardiac and skeletal muscles and which play important roles in the assembly and repair of myofibrils and their attachment to the membrane. We identified the dystrophin-binding protein aciculin (also known as phosphoglucomutase-like protein 5, PGM5) as a new interaction partner of FLNc and Xin. All three proteins colocalized at intercalated discs of cardiac muscle and myotendinous junctions of skeletal muscle, whereas FLNc and aciculin also colocalized in mature Z-discs. Bimolecular fluorescence complementation experiments in developing cultured mammalian skeletal muscle cells demonstrated that Xin and aciculin also interact in FLNc-containing immature myofibrils and areas of myofibrillar remodeling and repair induced by electrical pulse stimulation (EPS). Fluorescence recovery after photobleaching (FRAP) experiments showed that aciculin is a highly dynamic and mobile protein. Aciculin knockdown in myotubes led to failure in myofibril assembly, alignment and membrane attachment, and a massive reduction in myofibril number. A highly similar phenotype was found upon depletion of aciculin in zebrafish embryos. Our results point to a thus far unappreciated, but essential, function of aciculin in myofibril formation, maintenance and remodeling.
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Affiliation(s)
- Sibylle Molt
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - John B Bührdel
- Department of Internal Medicine II, University of Ulm, 89081 Ulm, Germany
| | - Sergiy Yakovlev
- University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Peter Schein
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | | | - Gregor Kirfel
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Lilli Winter
- Department of Biochemistry and Molecular Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Gerhard Wiche
- Department of Biochemistry and Molecular Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | | | - Wolfgang Rottbauer
- Department of Internal Medicine II, University of Ulm, 89081 Ulm, Germany
| | - Steffen Just
- Department of Internal Medicine II, University of Ulm, 89081 Ulm, Germany
| | - Alexey M Belkin
- University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Dieter O Fürst
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
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24
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Chen H, Chandrasekar S, Sheetz MP, Stossel TP, Nakamura F, Yan J. Mechanical perturbation of filamin A immunoglobulin repeats 20-21 reveals potential non-equilibrium mechanochemical partner binding function. Sci Rep 2014; 3:1642. [PMID: 23571456 PMCID: PMC3622079 DOI: 10.1038/srep01642] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 03/26/2013] [Indexed: 12/29/2022] Open
Abstract
The actin crosslinking protein filamin A (FLNa) mediates mechanotransduction, a conversion of mechanical forces into cellular biochemical signals to regulate cell growth and survival. To provide more quantitative insight into this process, we report results using magnetic tweezers that relate mechanical force to conformational changes of FLNa immunoglobulin-like repeats (IgFLNa) 20–21, previously identified as a mechanosensing domain. We determined the force magnitudes required to unfold previously identified structural organizations of the β-strands in the two domains: IgFLNa 20 unfolds at ~15 pN and IgFLNa 21 unfolding requires significantly larger forces. Unfolded domain IgFLNa 20 can exist in two different conformational states, which lead to different refolding kinetics of the IgFLNa 20 and imply a significant impact on the reformation of the domain pair at reduced force values. We discuss the relevance of the findings to force bearing and mechanosensing functions of FLNa.
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Affiliation(s)
- Hu Chen
- Mechanobiology Institute, National University of Singapore, Singapore 117411
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25
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Force-dependent isomerization kinetics of a highly conserved proline switch modulates the mechanosensing region of filamin. Proc Natl Acad Sci U S A 2014; 111:5568-73. [PMID: 24706888 DOI: 10.1073/pnas.1319448111] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Proline switches, controlled by cis-trans isomerization, have emerged as a particularly effective regulatory mechanism in a wide range of biological processes. In this study, we use single-molecule mechanical measurements to develop a full kinetic and energetic description of a highly conserved proline switch in the force-sensing domain 20 of human filamin and how prolyl isomerization modulates the force-sensing mechanism. Proline isomerization toggles domain 20 between two conformations. A stable cis conformation with slow unfolding, favoring the autoinhibited closed conformation of filamin's force-sensing domain pair 20-21, and a less stable, uninhibited conformation promoted by the trans form. The data provide detailed insight into the folding mechanisms that underpin the functionality of this binary switch and elucidate its remarkable efficiency in modulating force-sensing, thus combining two previously unconnected regulatory mechanisms, proline switches and mechanosensing.
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26
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Sethi R, Seppälä J, Tossavainen H, Ylilauri M, Ruskamo S, Pentikäinen OT, Pentikäinen U, Permi P, Ylänne J. A novel structural unit in the N-terminal region of filamins. J Biol Chem 2014; 289:8588-98. [PMID: 24469451 DOI: 10.1074/jbc.m113.537456] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Immunoglobulin-like (Ig) domains are a widely expanded superfamily that act as interaction motifs or as structural spacers in multidomain proteins. Vertebrate filamins (FLNs), which are multifunctional actin-binding proteins, consist of 24 Ig domains. We have recently discovered that in the C-terminal rod 2 region of FLN, Ig domains interact with each other forming functional domain pairs, where the interaction with signaling and transmembrane proteins is mechanically regulated by weak actomyosin contraction forces. Here, we investigated if there are similar inter-domain interactions around domain 4 in the N-terminal rod 1 region of FLN. Protein crystal structures revealed a new type of domain organization between domains 3, 4, and 5. In this module, domains 4 and 5 interact rather tightly, whereas domain 3 has a partially flexible interface with domain 4. NMR peptide titration experiments showed that within the three-domain module, domain 4 is capable for interaction with a peptide derived from platelet glycoprotein Ib. Crystal structures of FLN domains 4 and 5 in complex with the peptide revealed a typical β sheet augmentation interaction observed for many FLN ligands. Domain 5 was found to stabilize domain 4, and this could provide a mechanism for the regulation of domain 4 interactions.
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Affiliation(s)
- Ritika Sethi
- From the Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, P. O. Box 35, Survontie 9, 40014 Jyväskylä
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27
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Hytönen VP, Wehrle-Haller B. Protein conformation as a regulator of cell–matrix adhesion. Phys Chem Chem Phys 2014; 16:6342-57. [DOI: 10.1039/c3cp54884h] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Conformational changes within proteins play key roles in the regulation of cell–matrix adhesion. We discuss the mechanisms involved in conformational regulation, including mechanical signals, posttranslational modifications and intrinsically disordered proteins.
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Affiliation(s)
- Vesa P. Hytönen
- University of Tampere
- Institute of Biomedical Technology and BioMediTech
- 33520 Tampere, Finland
- Fimlab Laboratories
- 33014 Tampere, Finland
| | - Bernhard Wehrle-Haller
- University of Geneva
- Department of Cell Physiology and Metabolism
- Centre Médical Universitaire
- 1211 Geneva 4, Switzerland
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28
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Pinto VI, Senini VW, Wang Y, Kazembe MP, McCulloch CA. Filamin A protects cells against force-induced apoptosis by stabilizing talin- and vinculin-containing cell adhesions. FASEB J 2014; 28:453-63. [PMID: 24097310 DOI: 10.1096/fj.13-233759] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In mechanically loaded tissues such as weight-bearing joints, myocardium, and periodontal ligament, pathophysiological forces can disrupt cell-matrix contacts, which can induce cell death, leading to tissue and organ dysfunction. Protection against force-induced cell death may be mediated by filamin A (FLNa), an actin-binding protein that regulates β1 integrin-mediated cell adhesion. We examined the affect of filamin expression on collagen distribution and cell death in the periodontal ligament, a force-loaded tissue. Conditional deletion of FLNa in fibroblasts was associated with 2-fold increase of acellular areas in periodontal ligament and 7-fold higher proportions of apoptotic cells. In cultured fibroblasts with FLNa knockdown, we examined the affect of supraphysiological forces (1 pN/μm(2) cell area; applied through the β1 integrin) on recruitment of talin and vinculin to focal adhesions and on apoptosis. Compared with the wild type, FLNa-knockdown cells exhibited 3-fold increases in floating cells after overnight force application and a 2-fold increase in cell detachment. Force induced time-dependent reductions (P<0.05) in the numbers of activated β1 integrin-, talin-, and vinculin-stained adhesions in FLNa-knockdown compared with those in wild-type cells. We conclude that FLNa protects against apoptosis in force-loaded cells, and this protection is mediated by enhanced formation and maturation of matrix adhesions.
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Affiliation(s)
- Vanessa I Pinto
- 1Room 244, Fitzgerald Building, 150 College St., University of Toronto, Toronto, ON, M5S 3E2, Canada.
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Jahed Z, Shams H, Mehrbod M, Mofrad MRK. Mechanotransduction pathways linking the extracellular matrix to the nucleus. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 310:171-220. [PMID: 24725427 DOI: 10.1016/b978-0-12-800180-6.00005-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cells contain several mechanosensing components that transduce mechanical signals into biochemical cascades. During cell-ECM adhesion, a complex network of molecules mechanically couples the extracellular matrix (ECM), cytoskeleton, and nucleoskeleton. The network comprises transmembrane receptor proteins and focal adhesions, which link the ECM and cytoskeleton. Additionally, recently identified protein complexes extend this linkage to the nucleus by linking the cytoskeleton and the nucleoskeleton. Despite numerous studies in this field, due to the complexity of this network, our knowledge of the mechanisms of cell-ECM adhesion at the molecular level remains remarkably incomplete. Herein, we present a review of the structures of key molecules involved in cell-ECM adhesion, along with an evaluation of their predicted roles in mechanical sensing. Additionally, specific binding events prompted by force-induced conformational changes of each molecule are discussed. Finally, we propose a model for the biomechanical events prominent in cell-ECM adhesion.
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Affiliation(s)
- Zeinab Jahed
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California at Berkeley, Berkeley, California, USA
| | - Hengameh Shams
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California at Berkeley, Berkeley, California, USA
| | - Mehrdad Mehrbod
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California at Berkeley, Berkeley, California, USA
| | - Mohammad R K Mofrad
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California at Berkeley, Berkeley, California, USA.
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Molecular Mechanisms Underlying the Force-Dependent Regulation of Actin-to-ECM Linkage at the Focal Adhesions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 126:135-54. [DOI: 10.1016/b978-0-12-394624-9.00006-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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31
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Xu T, Lannon H, Wolf S, Nakamura F, Brujic J. Domain-domain interactions in filamin A (16-23) impose a hierarchy of unfolding forces. Biophys J 2013; 104:2022-30. [PMID: 23663845 DOI: 10.1016/j.bpj.2013.03.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 03/10/2013] [Accepted: 03/19/2013] [Indexed: 01/10/2023] Open
Abstract
The quaternary structure of Filamin A (FLNa) 16-23 was recently shown to exhibit multiple domain-domain interactions that lead to a propeller-like construction. Here we present single-molecule force spectroscopy experiments to show a wide variety of mechanical responses of this molecule and compare it with its linear counterpart FLNa 1-8. The compact structure of FLNa 16-23 leads to a broad distribution of rupture forces and end-to-end lengths in the force-extension mode and multiple unraveling timescales in the force-clamp mode. Moreover, a subset of force-extension trajectories reveals a mechanical hierarchy in which the rupture of domain-domain interactions at high forces (>200 pN) liberates the unfolding of individual domains at low forces (∼100 pN). This mechanism may also explain the order-of-magnitude difference in the rates of the biexponential fits to the distribution of unfolding dwell times under force-clamp. Overall, FLNa 16-23 under a force of 100 pN is more compliant than the linear FLNa 1-8. Because a physiological role of FLNa is to crosslink actin filaments, this range of responses allows it to accommodate a broad spectrum of forces exerted by the cell and its environment.
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Affiliation(s)
- Tianyou Xu
- Department of Physics and Center for Soft Matter Research, New York University, New York, New York, USA
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Ylilauri M, Pentikäinen OT. MMGBSA as a tool to understand the binding affinities of filamin-peptide interactions. J Chem Inf Model 2013; 53:2626-33. [PMID: 23988151 DOI: 10.1021/ci4002475] [Citation(s) in RCA: 192] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Filamins (FLN) are large dimeric proteins that cross-link actin and work as important scaffolds in human cells. FLNs consist of an N-terminal actin-binding domain followed by 24 immunoglobulin-like domains (FLN1-24). FLN domains are divided into four subgroups based on their amino acid sequences. One of these subgroups, including domains 4, 9, 12, 17, 19, 21, and 23, shares a similar ligand-binding site between the β strands C and D. Several proteins, such as integrins β2 and β7, glycoprotein Ibα (GPIbα), and migfilin, have been shown to bind to this site. Here, we computationally estimated the binding free energies of filamin A (FLNa) subunits with bound peptides using the molecular mechanics-generalized Born surface area (MMGBSA) method. The obtained computational results correlated well with the experimental data, and they ranked efficiently both the binding of one ligand to all used FLNa-domains and the binding of all used ligands to FLNa21. Furthermore, the steered molecular dynamics (SMD) simulations pinpointed the binding hot spots for these complexes. These results demonstrate that molecular dynamics combined with free energy calculations are applicable to estimating the energetics of protein-protein interactions and can be used to direct the development of novel FLN function modulators.
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Affiliation(s)
- Mikko Ylilauri
- Computational Bioscience Laboratory, Department of Biological and Environmental Science & Nanoscience Center, University of Jyväskylä , P.O. Box 35, Jyväskylä FI-40014, Finland
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Bouvard D, Pouwels J, De Franceschi N, Ivaska J. Integrin inactivators: balancing cellular functions in vitro and in vivo. Nat Rev Mol Cell Biol 2013; 14:430-42. [DOI: 10.1038/nrm3599] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Filamin and phospholipase C-ε are required for calcium signaling in the Caenorhabditis elegans spermatheca. PLoS Genet 2013; 9:e1003510. [PMID: 23671426 PMCID: PMC3650001 DOI: 10.1371/journal.pgen.1003510] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 03/30/2013] [Indexed: 12/05/2022] Open
Abstract
The Caenorhabditis elegans spermatheca is a myoepithelial tube that stores sperm and undergoes cycles of stretching and constriction as oocytes enter, are fertilized, and exit into the uterus. FLN-1/filamin, a stretch-sensitive structural and signaling scaffold, and PLC-1/phospholipase C-ε, an enzyme that generates the second messenger IP3, are required for embryos to exit normally after fertilization. Using GCaMP, a genetically encoded calcium indicator, we show that entry of an oocyte into the spermatheca initiates a distinctive series of IP3-dependent calcium oscillations that propagate across the tissue via gap junctions and lead to constriction of the spermatheca. PLC-1 is required for the calcium release mechanism triggered by oocyte entry, and FLN-1 is required for timely initiation of the calcium oscillations. INX-12, a gap junction subunit, coordinates propagation of the calcium transients across the spermatheca. Gain-of-function mutations in ITR-1/IP3R, an IP3-dependent calcium channel, and loss-of-function mutations in LFE-2, a negative regulator of IP3 signaling, increase calcium release and suppress the exit defect in filamin-deficient animals. We further demonstrate that a regulatory cassette consisting of MEL-11/myosin phosphatase and NMY-1/non-muscle myosin is required for coordinated contraction of the spermatheca. In summary, this study answers long-standing questions concerning calcium signaling dynamics in the C. elegans spermatheca and suggests FLN-1 is needed in response to oocyte entry to trigger calcium release and coordinated contraction of the spermathecal tissue. During organism development and normal physiological function cells sense, integrate, and respond to a variety of cues or signals including biochemical and mechanical stimuli. In this study we used Caenorhabditis elegans, a small transparent worm, to study filamin (FLN-1), a structural protein that may act as a molecular strain gauge. The C. elegans spermatheca is a contractile tube that is stretched during normal function, making it an ideal candidate for study of how cells respond to stretch. Oocytes are ovulated into the spermatheca, fertilized, and then pushed into the uterus by constriction of the spermatheca. The ability of the spermatheca to constrict depends on inositol 1,4,5-triphosphate (IP3), a signaling molecule produced by the enzyme phospholipase C (PLC-1) that triggers calcium release within cells. In animals with mutated FLN-1 or PLC-1 the spermathecal cells fail to constrict. Using genetic analysis and a calcium-sensitive fluorescent protein, we show that FLN-1 functions with PLC-1 to regulate IP3 production, calcium release, and contraction of the spermatheca. Filamin may function to sense stretch caused by entering oocytes and to trigger constriction. These findings establish a link between filamin and calcium signaling that may apply to similar signaling pathways in other systems.
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Yue J, Huhn S, Shen Z. Complex roles of filamin-A mediated cytoskeleton network in cancer progression. Cell Biosci 2013; 3:7. [PMID: 23388158 PMCID: PMC3573937 DOI: 10.1186/2045-3701-3-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 01/10/2013] [Indexed: 01/08/2023] Open
Abstract
Filamin-A (FLNA), also called actin-binding protein 280 (ABP-280), was originally identified as a non-muscle actin binding protein, which organizes filamentous actin into orthogonal networks and stress fibers. Filamin-A also anchors various transmembrane proteins to the actin cytoskeleton and provides a scaffold for a wide range of cytoplasmic and nuclear signaling proteins. Intriguingly, several studies have revealed that filamin-A associates with multiple non-cytoskeletal proteins of diverse function and is involved in several unrelated pathways. Mutations and aberrant expression of filamin-A have been reported in human genetic diseases and several types of cancer. In this review, we discuss the implications of filamin-A in cancer progression, including metastasis and DNA damage response.
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Affiliation(s)
- Jingyin Yue
- Department of Radiation Oncology, The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, New Brunswick, NJ, 08903, USA.
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36
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Dynamic force sensing of filamin revealed in single-molecule experiments. Proc Natl Acad Sci U S A 2012; 109:19679-84. [PMID: 23150587 DOI: 10.1073/pnas.1211274109] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mechanical forces are important signals for cell response and development, but detailed molecular mechanisms of force sensing are largely unexplored. The cytoskeletal protein filamin is a key connecting element between the cytoskeleton and transmembrane complexes such as integrins or the von Willebrand receptor glycoprotein Ib. Here, we show using single-molecule mechanical measurements that the recently reported Ig domain pair 20-21 of human filamin A acts as an autoinhibited force-activatable mechanosensor. We developed a mechanical single-molecule competition assay that allows online observation of binding events of target peptides in solution to the strained domain pair. We find that filamin force sensing is a highly dynamic process occurring in rapid equilibrium that increases the affinity to the target peptides by up to a factor of 17 between 2 and 5 pN. The equilibrium mechanism we find here can offer a general scheme for cellular force sensing.
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The C-terminal rod 2 fragment of filamin A forms a compact structure that can be extended. Biochem J 2012; 446:261-9. [PMID: 22676060 DOI: 10.1042/bj20120361] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Filamins are large proteins that cross-link actin filaments and connect to other cellular components. The C-terminal rod 2 region of FLNa (filamin A) mediates dimerization and interacts with several transmembrane receptors and intracellular signalling adaptors. SAXS (small-angle X-ray scattering) experiments were used to make a model of a six immunoglobulin-like domain fragment of the FLNa rod 2 (domains 16-21). This fragment had a surprising three-branched structural arrangement, where each branch was made of a tightly packed two-domain pair. Peptides derived from transmembrane receptors and intracellular signalling proteins induced a more open structure of the six domain fragment. Mutagenesis studies suggested that these changes are caused by peptides binding to the CD faces on domains 19 and 21 which displace the preceding domain A-strands (18 and 20 respectively), thus opening the individual domain pairs. A single particle cryo-EM map of a nine domain rod 2 fragment (domains 16-24), showed a relatively compact dimeric particle and confirmed the three-branched arrangement as well as the peptide-induced conformation changes. These findings reveal features of filamin structure that are important for its interactions and mechanical properties.
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38
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Vial D, McKeown-Longo PJ. Epidermal growth factor (EGF) regulates α5β1 integrin activation state in human cancer cell lines through the p90RSK-dependent phosphorylation of filamin A. J Biol Chem 2012; 287:40371-80. [PMID: 23007402 DOI: 10.1074/jbc.m112.389577] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Regulation of integrin activation has important implications for tumor cell invasion and metastasis. RESULTS EGF activates ERK/p90RSK and Rho/Rho kinase signaling in A431 and DiFi colon cancer cells, leading to phosphorylation of filamin A (FLNa) and inactivation of the α5β1 integrin receptor. CONCLUSION EGF promotes α5β1 inactivation through the p90RSK-dependent phosphorylation of FLNa. SIGNIFICANCE We have identified a novel EGF-dependent mechanism controlling the α5β1 integrin activation state. Cell adhesion, motility, and invasion are regulated by the ligand-binding activity of integrin receptors, transmembrane proteins that bind to the extracellular matrix. Integrins whose conformation allows for ligand binding and appropriate functional activity are said to be in an active state. Integrin activation and subsequent ligand binding are dynamically regulated by the association of cytoplasmic proteins with integrin intracellular domains. In this study, we evaluated the role of EGF in the regulation of the activation state of the α5β1 integrin receptor for fibronectin. The addition of EGF to either A431 squamous carcinoma cells or DiFi colon cancer cells resulted in loss of α5β1-dependent adhesion to fibronectin but no loss of integrin from the cell surface. EGF activated the EGF receptor/ERK/p90RSK and Rho/Rho kinase signaling pathways. Blocking either pathway inhibited EGF-mediated loss of adhesion, suggesting that they work in parallel to regulate integrin function. EGF treatment also resulted in phosphorylation of filamin A (FLNa), which binds and inactivates β1 integrins. EGF-mediated FLNa phosphorylation was completely blocked by an inhibitor of p90RSK and partially attenuated by an inhibitor of Rho kinase, suggesting that both pathways converge on FLNa to regulate integrin function. A431 clonal cell lines expressing non-phosphorylated dominant-negative FLNa were resistant to the inhibitory effects of EGF on integrin function, whereas clonal cell lines overexpressing wild-type FLNa were more sensitive to the inhibitory effect of EGF. These data suggest that EGF-dependent inactivation of α5β1 integrin is regulated through FLNa phosphorylation and cellular contractility.
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Affiliation(s)
- Daniel Vial
- Center for Cell Biology and Cancer Research, Albany Medical College, Albany, NY 12208, USA
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39
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Abstract
A new study suggests that mechanical strain through the actin-binding protein filamin A leads to increased linkage between the extracellular matrix and cytoskeleton and decreased actin dynamics.
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40
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Roca-Cusachs P, Iskratsch T, Sheetz MP. Finding the weakest link: exploring integrin-mediated mechanical molecular pathways. J Cell Sci 2012; 125:3025-38. [PMID: 22797926 DOI: 10.1242/jcs.095794] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
From the extracellular matrix to the cytoskeleton, a network of molecular links connects cells to their environment. Molecules in this network transmit and detect mechanical forces, which subsequently determine cell behavior and fate. Here, we reconstruct the mechanical pathway followed by these forces. From matrix proteins to actin through integrins and adaptor proteins, we review how forces affect the lifetime of bonds and stretch or alter the conformation of proteins, and how these mechanical changes are converted into biochemical signals in mechanotransduction events. We evaluate which of the proteins in the network can participate in mechanotransduction and which are simply responsible for transmitting forces in a dynamic network. Besides their individual properties, we also analyze how the mechanical responses of a protein are determined by their serial connections from the matrix to actin, their parallel connections in integrin clusters and by the rate at which force is applied to them. All these define mechanical molecular pathways in cells, which are emerging as key regulators of cell function alongside better studied biochemical pathways.
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Affiliation(s)
- Pere Roca-Cusachs
- University of Barcelona and Institute for Bioengineering of Catalonia, Barcelona, Spain.
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41
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Tossavainen H, Koskela O, Jiang P, Ylänne J, Campbell ID, Kilpeläinen I, Permi P. Model of a Six Immunoglobulin-Like Domain Fragment of Filamin A (16–21) Built Using Residual Dipolar Couplings. J Am Chem Soc 2012; 134:6660-72. [DOI: 10.1021/ja2114882] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Helena Tossavainen
- Program in
Structural Biology
and Biophysics, Institute of Biotechnology, University of Helsinki, Viikinkaari
1, P.O. Box 65, FI-00014 Helsinki, Finland
| | - Outi Koskela
- Laboratory of Organic Chemistry, Department
of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Pengju Jiang
- Biochemistry Department, University of Oxford, Oxford, OX1 3QU
United Kingdom
- School of Pharmaceutical Engineering & Life Science, Changzhou University, Changzhou, 213164 China
| | - Jari Ylänne
- Department of Biological
and Environmental Science and Nanoscience Center, University of Jyväskylä, P.O. Box 35,
FI-40014 Jyväskylä, Finland
| | - Iain D. Campbell
- Biochemistry Department, University of Oxford, Oxford, OX1 3QU
United Kingdom
| | - Ilkka Kilpeläinen
- Laboratory of Organic Chemistry, Department
of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Perttu Permi
- Program in
Structural Biology
and Biophysics, Institute of Biotechnology, University of Helsinki, Viikinkaari
1, P.O. Box 65, FI-00014 Helsinki, Finland
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Su W, Mruk DD, Cheng CY. Filamin A: A regulator of blood-testis barrier assembly during post-natal development. SPERMATOGENESIS 2012; 2:73-78. [PMID: 22670216 PMCID: PMC3364794 DOI: 10.4161/spmg.20223] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Filamins are a family of actin-binding proteins composed of filamin A, B and C. Besides of their ability to induce perpendicular branching of F-actin filaments via their actin binding domains near the N-terminus, filamins can regulate multiple cellular functions because of their unique ability to recruit more than 90 protein binding partners to their primary sequences which are having highly diversified cellular functions. However, this family of proteins has not been examined in the testis until recently. Herein, we highlight recent findings in the field regarding the role of these proteins in cell epithelia, and based on recent data in the testis regarding their role on spermatogenesis, this review provides the basis for future functional studies.
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Affiliation(s)
- Wenhui Su
- The Mary M. Wohlford Laboratory for Male Contraceptive Research; Center for Biomedical Research; The Population Council; New York, NY USA
- Department of Biochemistry and Molecular Biology; China Medical University; Shen Yang, China
| | - Dolores D. Mruk
- The Mary M. Wohlford Laboratory for Male Contraceptive Research; Center for Biomedical Research; The Population Council; New York, NY USA
| | - C. Yan Cheng
- The Mary M. Wohlford Laboratory for Male Contraceptive Research; Center for Biomedical Research; The Population Council; New York, NY USA
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Abstract
Filamins are essential, evolutionarily conserved, modular, multidomain, actin-binding proteins that organize the actin cytoskeleton and maintain extracellular matrix connections by anchoring actin filaments to transmembrane receptors. By cross-linking and anchoring actin filaments, filamins stabilize the plasma membrane, provide cellular cortical rigidity, and contribute to the mechanical stability of the plasma membrane and the cell cortex. In addition to binding actin, filamins interact with more than 90 other binding partners including intracellular signaling molecules, receptors, ion channels, transcription factors, and cytoskeletal and adhesion proteins. Thus, filamins scaffold a wide range of signaling pathways and are implicated in the regulation of a diverse array of cellular functions including motility, maintenance of cell shape, and differentiation. Here, we review emerging structural and functional evidence that filamins are mechanosensors and/or mechanotransducers playing essential roles in helping cells detect and respond to physical forces in their local environment.
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Affiliation(s)
- Ziba Razinia
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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44
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Differential mechanical stability of filamin A rod segments. Biophys J 2011; 101:1231-7. [PMID: 21889461 DOI: 10.1016/j.bpj.2011.07.028] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 06/23/2011] [Accepted: 07/18/2011] [Indexed: 01/08/2023] Open
Abstract
Prompted by recent reports suggesting that interaction of filamin A (FLNa) with its binding partners is regulated by mechanical force, we examined mechanical properties of FLNa domains using magnetic tweezers. FLNa, an actin cross-linking protein, consists of two subunits that dimerize through a C-terminal self-association domain. Each subunit contains an N-terminal spectrin-related actin-binding domain followed by 24 immunoglobulinlike (Ig) repeats. The Ig repeats in the rod 1 segment (repeats 1-15) are arranged as a linear array, whereas rod 2 (repeats 16-23) is more compact due to interdomain interactions. In the rod 1 segment, repeats 9-15 augment F-actin binding to a much greater extent than do repeats 1-8. Here, we report that the three segments are unfolded at different forces under the same loading rate. Remarkably, we found that repeats 16-23 are susceptible to forces of ∼10 pN or even less, whereas the repeats in the rod 1 segment can withstand significantly higher forces. The differential force response of FLNa Ig domains has broad implications, since these domains not only support the tension of actin network but also interact with many transmembrane and signaling proteins, mostly in the rod 2 segment. In particular, our finding of unfolding of repeats 16-23 at ∼10 pN or less is consistent with the hypothesized force-sensing function of the rod 2 segment in FLNa.
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45
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Ehrlicher AJ, Nakamura F, Hartwig JH, Weitz DA, Stossel TP. Mechanical strain in actin networks regulates FilGAP and integrin binding to filamin A. Nature 2011; 478:260-3. [PMID: 21926999 PMCID: PMC3204864 DOI: 10.1038/nature10430] [Citation(s) in RCA: 265] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 08/05/2011] [Indexed: 12/14/2022]
Affiliation(s)
- A J Ehrlicher
- Translational Medicine Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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Razinia Z, Baldassarre M, Bouaouina M, Lamsoul I, Lutz PG, Calderwood DA. The E3 ubiquitin ligase specificity subunit ASB2α targets filamins for proteasomal degradation by interacting with the filamin actin-binding domain. J Cell Sci 2011; 124:2631-41. [PMID: 21750192 DOI: 10.1242/jcs.084343] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Filamins are an important family of actin-binding and crosslinking proteins that mediate remodeling of the actin cytoskeleton and maintain extracellular matrix connections by anchoring transmembrane proteins to actin filaments and linking them to intracellular signaling cascades. We recently found that filamins are targeted for proteasomal degradation by the E3 ubiquitin ligase specificity subunit ASBα and that acute degradation of filamins through this ubiquitin-proteasome pathway correlates with cell differentiation. Specifically, in myeloid leukemia cells retinoic-acid-induced expression of ASB2α triggers filamin degradation and recapitulates early events crucial for cell differentiation. ASB2α is thought to link substrates to the ubiquitin transferase machinery; however, the mechanism by which ASB2α interacts with filamin to induce degradation remained unknown. Here, we use cell-based and biochemical assays to show that the subcellular localization of ASB2α to actin-rich structures is dependent on filamin and that the actin-binding domain (ABD) of filamin mediates the interaction with ASB2α. Furthermore, we show that the ABD is necessary and sufficient for ASB2α-mediated filamin degradation. We propose that ASB2α exerts its effect by binding the ABD and mediating its polyubiquitylation, so targeting filamins for degradation. These studies provide the molecular basis for ASB2α-mediated filamin degradation and unravel an important mechanism by which filamin levels can be acutely regulated.
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Affiliation(s)
- Ziba Razinia
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520-8066, USA
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47
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Pentikäinen U, Jiang P, Takala H, Ruskamo S, Campbell ID, Ylänne J. Assembly of a filamin four-domain fragment and the influence of splicing variant-1 on the structure. J Biol Chem 2011; 286:26921-30. [PMID: 21636571 DOI: 10.1074/jbc.m110.195958] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Filamins are scaffold proteins that bind to various proteins, including the actin cytoskeleton, integrin adhesion receptors, and adaptor proteins such as migfilin. Alternative splicing of filamin, largely constructed from 24 Ig-like domains, is thought to have a role in regulating its interactions with other proteins. The filamin A splice variant-1 (FLNa var-1) lacks 41 amino acids, including the last β-strand of domain 19, FLNa(19), and the first β-strand of FLNa(20) that was previously shown to mask a key binding site on FLNa(21). Here, we present a structural characterization of domains 18-21, FLNa(18-21), in the FLNa var-1 as well as its nonspliced counterpart. A model of nonspliced FLNa(18-21), obtained from small angle x-ray scattering data, shows that these four domains form an L-shaped structure, with one arm composed of a pair of domains. NMR spectroscopy reveals that in the splice variant, FLNa(19) is unstructured whereas the other domains retain the same fold as in their canonical counterparts. The maximum dimensions predicted by small angle x-ray scattering data are increased upon migfilin binding in the FLNa(18-21) but not in the splice variant, suggesting that migfilin binding is able to displace the masking β-strand and cause a rearrangement of the structure. Possible function roles for the spliced variants are discussed.
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Affiliation(s)
- Ulla Pentikäinen
- Department of Biological and Environmental Science and Nanoscience Center, P. O. Box 35, University of Jyväskylä, Jyväskylä FI-40014, Finland.
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Ithychanda SS, Qin J. Evidence for multisite ligand binding and stretching of filamin by integrin and migfilin. Biochemistry 2011; 50:4229-31. [PMID: 21524097 PMCID: PMC3097901 DOI: 10.1021/bi2003229] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Filamin, a large cytoskeletal adaptor, connects plasma membrane to cytoskeleton by binding to transmembrane receptor integrin and actin. Seven of 24 filamin immunoglobulin repeats have conserved integrin binding sites, of which repeats 19 and 21 were shown to be autoinhibited by their adjacent repeats 18 and 20, respectively. Here we show using nuclear magnetic resonance spectroscopy that the autoinhibition can be relieved by integrin or integrin regulator migfilin. We further demonstrate that repeats 19 and 21 can simultaneously engage ligands. The data suggest that filamin is mechanically stretched by integrin or migfilin via a multisite binding mechanism for regulating cytoskeleton and integrin-mediated cell adhesion.
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Affiliation(s)
- Sujay Subbayya Ithychanda
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Jun Qin
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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Nakamura F, Stossel TP, Hartwig JH. The filamins: organizers of cell structure and function. Cell Adh Migr 2011; 5:160-9. [PMID: 21169733 DOI: 10.4161/cam.5.2.14401] [Citation(s) in RCA: 351] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Filamin A (FLNa), the first non-muscle actin filament cross-linking protein, was identified in 1975. Thirty five years of FLNa research has revealed its structure in great detail, discovered its isoforms (FLNb and c), and identified over 90 binding partners including channels, receptors, intracellular signaling molecules, and even transcription factors. Due to this diversity, mutations in human FLN genes result in a wide range of anomalies with moderate to lethal consequences. This review focuses on the structure and functions of FLNa in cell migration and adhesion.
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Affiliation(s)
- Fumihiko Nakamura
- Translational Medicine Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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Sutherland-Smith AJ. Filamin structure, function and mechanics: are altered filamin-mediated force responses associated with human disease? Biophys Rev 2011; 3:15-23. [PMID: 28510233 DOI: 10.1007/s12551-011-0042-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 01/03/2011] [Indexed: 01/08/2023] Open
Abstract
The cytoskeleton framework is essential not only for cell structure and stability but also for dynamic processes such as cell migration, division and differentiation. The F-actin cytoskeleton is mechanically stabilised and regulated by various actin-binding proteins, one family of which are the filamins that cross-link F-actin into networks that greatly alter the elastic properties of the cytoskeleton. Filamins also interact with cell membrane-associated extracellular matrix receptors and intracellular signalling proteins providing a potential mechanism for cells to sense their external environment by linking these signalling systems. The stiffness of the external matrix to which cells are attached is an important environmental variable for cellular behaviour. In order for a cell to probe matrix stiffness, a mechanosensing mechanism functioning via alteration of protein structure and/or binding events in response to external tension is required. Current structural, mechanical, biochemical and human disease-associated evidence suggests filamins are good candidates for a role in mechanosensing.
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Affiliation(s)
- Andrew J Sutherland-Smith
- Institute of Molecular BioSciences, Massey University, Private Bag 11222, Palmerston North, 4442, New Zealand.
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