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Müller M, Mazur AJ, Behrmann E, Diensthuber RP, Radke MB, Qu Z, Littwitz C, Raunser S, Schoenenberger CA, Manstein DJ, Mannherz HG. Functional characterization of the human α-cardiac actin mutations Y166C and M305L involved in hypertrophic cardiomyopathy. Cell Mol Life Sci 2012; 69:3457-79. [PMID: 22643837 PMCID: PMC11115188 DOI: 10.1007/s00018-012-1030-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 04/22/2012] [Accepted: 05/07/2012] [Indexed: 11/25/2022]
Abstract
Inherited cardiomyopathies are caused by point mutations in sarcomeric gene products, including α-cardiac muscle actin (ACTC1). We examined the biochemical and cell biological properties of the α-cardiac actin mutations Y166C and M305L identified in hypertrophic cardiomyopathy (HCM). Untagged wild-type (WT) cardiac actin, and the Y166C and M305L mutants were expressed by the baculovirus/Sf9-cell system and affinity purified by immobilized gelsolin G4-6. Their correct folding was verified by a number of assays. The mutant actins also displayed a disturbed intrinsic ATPase activity and an altered polymerization behavior in the presence of tropomyosin, gelsolin, and Arp2/3 complex. Both mutants stimulated the cardiac β-myosin ATPase to only 50 % of WT cardiac F-actin. Copolymers of WT and increasing amounts of the mutant actins led to a reduced stimulation of the myosin ATPase. Transfection of established cell lines revealed incorporation of EGFP- and hemagglutinin (HA)-tagged WT and both mutant actins into cytoplasmic stress fibers. Adenoviral vectors of HA-tagged WT and Y166C actin were successfully used to infect adult and neonatal rat cardiomyocytes (NRCs). The expressed HA-tagged actins were incorporated into the minus-ends of NRC thin filaments, demonstrating the ability to form hybrid thin filaments with endogenous actin. In NRCs, the Y166C mutant led after 72 h to a shortening of the sarcomere length when compared to NRCs infected with WT actin. Thus our data demonstrate that a mutant actin can be integrated into cardiomyocyte thin filaments and by its reduced mode of myosin interaction might be the basis for the initiation of HCM.
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Affiliation(s)
- Mirco Müller
- Institute for Biophysical Chemistry, OE 4350, Hannover Medical School, 30625 Hannover, Germany
| | - Antonina Joanna Mazur
- Department of Anatomy and Molecular Embryology, Ruhr-University, Universitätsstrasse 150, 44780 Bochum, Germany
- Present Address: Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, 51-148 Wroclaw, Poland
| | - Elmar Behrmann
- Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, 44227 Dortmund, Germany
| | - Ralph P. Diensthuber
- Institute for Biophysical Chemistry, OE 4350, Hannover Medical School, 30625 Hannover, Germany
| | - Michael B. Radke
- Institute for Biophysical Chemistry, OE 4350, Hannover Medical School, 30625 Hannover, Germany
| | - Zheng Qu
- Department of Anatomy and Molecular Embryology, Ruhr-University, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Christoph Littwitz
- Department of Physiology, Stritch School of Medicine, Loyola University Chicago, Chicago, USA
| | - Stefan Raunser
- Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, 44227 Dortmund, Germany
| | - Cora-Ann Schoenenberger
- Maurice E. Müller Institute for Structural Biology, Biozentrum, University of Basel, 4046 Basel, Switzerland
| | - Dietmar J. Manstein
- Institute for Biophysical Chemistry, OE 4350, Hannover Medical School, 30625 Hannover, Germany
| | - Hans Georg Mannherz
- Department of Anatomy and Molecular Embryology, Ruhr-University, Universitätsstrasse 150, 44780 Bochum, Germany
- Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, 44227 Dortmund, Germany
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Bonfils C, Bec N, Lacroix B, Harricane MC, Larroque C. Kinetic analysis of tubulin assembly in the presence of the microtubule-associated protein TOGp. J Biol Chem 2006; 282:5570-81. [PMID: 17178729 PMCID: PMC2238798 DOI: 10.1074/jbc.m605641200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The microtubule-associated protein TOGp, which belongs to a widely distributed protein family from yeasts to humans, is highly expressed in human tumors and brain tissue. From purified components we have determined the effect of TOGp on thermally induced tubulin association in vitro in the presence of 1 mm GTP and 3.4 m glycerol. Physicochemical parameters describing the mechanism of tubulin polymerization were deduced from the kinetic curves by application of the classical theoretical models of tubulin assembly. We have calculated from the polymerization time curves a range of parameters characteristic of nucleation, elongation, or steady state phase. In addition, the tubulin subunits turnover at microtubule ends was deduced from tubulin GTPase activity. For comparison, parallel experiments were conducted with colchicine and taxol, two drugs active on microtubules and with tau, a structural microtubule-associated protein from brain tissue. TOGp, which decreases the nucleus size and the tenth time of the reaction (the time required to produce 10% of the final amount of polymer), shortens the nucleation phase of microtubule assembly. In addition, TOGp favors microtubule formation by increasing the apparent first order rate constant of elongation. Moreover, TOGp increases the total amount of polymer by decreasing the tubulin critical concentration and by inhibiting depolymerization during the steady state of the reaction.
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Affiliation(s)
- Claude Bonfils
- INSERM, EMI 229, CRLC Val d'Aurelle, 34298 Montpellier, France.
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Usmanova A, Astier C, Méjean C, Hubert F, Feinberg J, Benyamin Y, Roustan C. Coevolution of actin and associated proteins: an alpha-actinin-like protein in a cyanobacterium (Spirulina platensis). Comp Biochem Physiol B Biochem Mol Biol 1998; 120:693-700. [PMID: 9854817 DOI: 10.1016/s0305-0491(98)10065-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Actin, together with associated proteins, such as myosin, cross-linking or capping proteins, has been observed in all eukaryotic cells. Presence of actin or actin-like proteins has also been reported in prokaryotic organisms belonging to the cyanobacteria. Our aim was first to extend the characterization of an actin-like protein to another prokaryotic cell, i.e. Spirulina, then to compare the antigenic reactivity of this new protein with that of Synechocystis and skeletal actins. We observed that some of the conserved antigenic epitopes corresponded to actin regions known to interact with cross-linking proteins. We also report for the first time that alpha-actinin and filamin purified from chicken gizzard both interact with a prokaryotic actin-like protein. Finally, we searched for the occurrence of a cross-linking protein in these cyanobacteria and identified a 105-kDa protein as an alpha-actinin-like protein using specific antibodies.
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Affiliation(s)
- A Usmanova
- UMR 5539 (CNRS), Université de Montpellier 2, France
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Feinberg J, Mery J, Heitz F, Benyamin Y, Roustan C. Conformational and functional studies of three gelsolin subdomain-1 synthetic peptides and their implication in actin polymerization. Biopolymers 1997; 41:647-55. [PMID: 9108732 DOI: 10.1002/(sici)1097-0282(199705)41:6<647::aid-bip5>3.0.co;2-q] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Gelsolin, a calcium and inositol phospholipid-sensitive protein, regulates actin filament length. Its activity is complex (capping, severing, etc.) and is supported by several functional domains. The N-terminal domain alone (S1), in particular, is able to impede actin polymerization. Our investigations were attempted to precise this inhibitory process by using synthetic peptides as models mimicking gelsolin S1 activity. Three peptides issued from S1 and located in gelsolin-actin interfaces were synthesized. The peptides (15-28, 42-55, and 96-114 sequences) were tested for their conformational and actin binding properties. Although the three peptides interact well with actin, only peptide 42-55 affects actin polymerization. A detailed kinetic study shows that the latter peptide essentially inhibits the nucleation step during actin polymerization. In conclusion, the present work shows that the binding of a synthetic peptide to a small sequence located outside the actin-actin interface is essential in the actin polymerization process.
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Affiliation(s)
- J Feinberg
- Centre de Recherches de Biochimie Macromoléculaire (CNRS), U.249 (INSERM), Université de Montpellier 1
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