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Oztug Durer ZA, McGillivary RM, Kang H, Elam WA, Vizcarra CL, Hanein D, De La Cruz EM, Reisler E, Quinlan ME. Metavinculin Tunes the Flexibility and the Architecture of Vinculin-Induced Bundles of Actin Filaments. J Mol Biol 2015; 427:2782-98. [PMID: 26168869 DOI: 10.1016/j.jmb.2015.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 07/06/2015] [Accepted: 07/07/2015] [Indexed: 11/19/2022]
Abstract
Vinculin is an abundant protein found at cell-cell and cell-extracellular matrix junctions. In muscles, a longer splice isoform of vinculin, metavinculin, is also expressed. The metavinculin-specific insert is part of the C-terminal tail domain, the actin-binding site of both isoforms. Mutations in the metavinculin-specific insert are linked to heart disease such as dilated cardiomyopathies. Vinculin tail domain (VT) both binds and bundles actin filaments. Metavinculin tail domain (MVT) binds actin filaments in a similar orientation but does not bundle filaments. Recently, MVT was reported to sever actin filaments. In this work, we asked how MVT influences F-actin alone or in combination with VT. Cosedimentation and limited proteolysis experiments indicated a similar actin binding affinity and mode for both VT and MVT. In real-time total internal reflection fluorescence microscopy experiments, MVT's severing activity was negligible. Instead, we found that MVT binding caused a 2-fold reduction in F-actin's bending persistence length and increased susceptibility to breakage. Using mutagenesis and site-directed labeling with fluorescence probes, we determined that MVT alters actin interprotomer contacts and dynamics, which presumably reflect the observed changes in bending persistence length. Finally, we found that MVT decreases the density and thickness of actin filament bundles generated by VT. Altogether, our data suggest that MVT alters actin filament flexibility and tunes filament organization in the presence of VT. Both of these activities are potentially important for muscle cell function. Perhaps MVT allows the load of muscle contraction to act as a signal to reorganize actin filaments.
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Affiliation(s)
- Zeynep A Oztug Durer
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA
| | - Rebecca M McGillivary
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA
| | - Hyeran Kang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - W Austin Elam
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - Christina L Vizcarra
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA
| | - Dorit Hanein
- Bioinformatics and Structural Biology Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Enrique M De La Cruz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095-1570, USA
| | - Margot E Quinlan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095-1570, USA.
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Rüdiger M, Korneeva N, Schwienbacher C, Weiss EE, Jockusch BM. Differential actin organization by vinculin isoforms: implications for cell type-specific microfilament anchorage. FEBS Lett 1998; 431:49-54. [PMID: 9684863 DOI: 10.1016/s0014-5793(98)00723-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Vinculin is found in all adherens junctions, while metavinculin, a larger splice variant, is coexpressed with vinculin only in smooth and cardiac muscle. To understand the significance of metavinculin expression, we compared ligand binding between turkey vinculin and metavinculin. Residues 1-258 were found essential for head-tail interactions in both proteins. The tail domains (VT and MVT, respectively) both bind to F-actin. However, while VT bundles F-actin, MVT generates highly viscous F-actin webs. In transfected PtK2 cells, VT causes F-actin needles or coils, while MVT-expressing cells display a diffuse F-actin distribution. Thus, the MVT-specific insert induces an F-actin supraorganization different from the VT-based form, suggesting that metavinculin has a specific role in muscle.
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Affiliation(s)
- M Rüdiger
- Cell Biology, Zoological Institute, Technical University Braunschweig, Germany
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Maeda M, Holder E, Lowes B, Valent S, Bies RD. Dilated cardiomyopathy associated with deficiency of the cytoskeletal protein metavinculin. Circulation 1997; 95:17-20. [PMID: 8994410 DOI: 10.1161/01.cir.95.1.17] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND The cytoskeleton plays an important role in maintaining cell structure and integrity. Defects in cytoskeletal proteins can cripple cell strength and may cause cardiomyopathy. We analyzed heart tissues from subjects with dilated cardiomyopathy for abnormalities in the cardiac cytoskeleton. Metavinculin, a cardiac isoform of the cytoskeletal protein vinculin, connects actin microfilaments to the intercalated disk and membrane costameres of the heart. METHODS AND RESULTS Metavinculin and vinculin transcripts and protein were analyzed by polymerase chain reaction (PCR) and Western blotting. Thirty-three human heart specimens were studied, including 5 normal controls, 4 subjects with ischemic cardiomyopathy, 1 with X-linked cardiomyopathy, and 23 with idiopathic dilated cardiomyopathy (IDC). PCR of cardiac cDNA detected absence of the metavinculin transcript in cardiac tissue from a subject with IDC. PCR of genomic DNA showed that the metavinculin exon was present but not utilized in the cardiac transcript. Western blot analysis demonstrated absence of metavinculin protein in the heart from this subject. Immunostaining of cardiac vinculin in this heart showed disorganized intercalated disk structures. Metavinculin deficiency was associated with normal cardiac expression of the cytoskeletal proteins vinculin, alpha-actinin, and dystrophin. Normal metavinculin expression in the other heart specimens suggests that the defect is specific in the IDC subject identified. CONCLUSIONS These results demonstrate an association between metavinculin deficiency and dilated cardiomyopathy due to a defect in alternative mRNA splicing.
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Affiliation(s)
- M Maeda
- Division of Cardiology, VA Medical Center, Denver, CO, USA
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O'Rourke F, Matthews E, Feinstein MB. Isolation of InsP4 and InsP6 binding proteins from human platelets: InsP4 promotes Ca2+ efflux from inside-out plasma membrane vesicles containing 104 kDa GAP1IP4BP protein. Biochem J 1996; 315 ( Pt 3):1027-34. [PMID: 8645140 PMCID: PMC1217257 DOI: 10.1042/bj3151027] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A low-density membrane fraction from human platelets contained the plasma membrane marker glycoprotein Ib (GpIb) and selective binding sites for InsP4 and InsP6. It was separated from the bulk of InsP3-receptor-containing membranes, but was heterogeneous, probably also containing surface-connected canalicular system and some lighter elements of the internal dense tubule system. After loading with calcium oxalate and re-centrifugation on Percoll gradients, this mixed fraction was subfractionated into light membranes containing all of the GpIb, high-affinity InsP4 binding sites (KD = 18 nM) and phosphate-stimulated Ca2+ transport activity. InsP4 (EC50 0.6 microM), but not InsP3 or InsP6, released up to 35% of the accumulated Ca2+ from these vesicles, which were shown to be inside-out plasma membrane vesicles by a biotinylation labelling technique and selective removal of right-side-out plasma membrane vesicles with streptavidin-agarose. Most of the InsP4, and all of the InsP6, binding was present in the much denser calcium oxalate-loaded subfractions, which were free of GpIb. InsP6 binding activity was chromatographically purified as a 116 kDa protein (KD for InsP6 = 5.9 nM), with an amino acid content and two internal peptide sequences identical to those of 116 kDa vinculin. A 104 kDa InsP4 binding protein (KD for InsP4 = 12 nM), probably identical to GAP1IP4BP described by Cullen, Hsuan, Truong, Letcher, Jackson, Dawson and Irvine [(1995) Nature (London) 376, 527-530], was also isolated. This InsP4 receptor may mediate Ca2+ influx in platelets that occurs subsequent to receptor-stimulated production of InsP3 and unloading of internal Ca2+ stores.
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Affiliation(s)
- F O'Rourke
- Department of Pharmacology, University of Connecticut School of Medicine, Farmington 06030, USA
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Johnson R, Craig S. An intramolecular association between the head and tail domains of vinculin modulates talin binding. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)99920-5] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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