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Ozsvar J, Yang C, Cain SA, Baldock C, Tarakanova A, Weiss AS. Tropoelastin and Elastin Assembly. Front Bioeng Biotechnol 2021; 9:643110. [PMID: 33718344 PMCID: PMC7947355 DOI: 10.3389/fbioe.2021.643110] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 02/08/2021] [Indexed: 12/12/2022] Open
Abstract
Elastic fibers are an important component of the extracellular matrix, providing stretch, resilience, and cell interactivity to a broad range of elastic tissues. Elastin makes up the majority of elastic fibers and is formed by the hierarchical assembly of its monomer, tropoelastin. Our understanding of key aspects of the assembly process have been unclear due to the intrinsic properties of elastin and tropoelastin that render them difficult to study. This review focuses on recent developments that have shaped our current knowledge of elastin assembly through understanding the relationship between tropoelastin’s structure and function.
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Affiliation(s)
- Jazmin Ozsvar
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Chengeng Yang
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States
| | - Stuart A Cain
- Wellcome Trust Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Clair Baldock
- Wellcome Trust Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Anna Tarakanova
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States.,Department of Mechanical Engineering, University of Connecticut, Storrs, CT, United States
| | - Anthony S Weiss
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia.,Sydney Nano Institute, The University of Sydney, Sydney, NSW, Australia
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2
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Yeo G, Baldock C, Wise SG, Weiss AS. Targeted Modulation of Tropoelastin Structure and Assembly. ACS Biomater Sci Eng 2017; 3:2832-2844. [PMID: 29152561 PMCID: PMC5686564 DOI: 10.1021/acsbiomaterials.6b00564] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 11/06/2016] [Indexed: 12/17/2022]
Abstract
Tropoelastin, as the monomer unit of elastin, assembles into elastic fibers that impart strength and resilience to elastic tissues. Tropoelastin is also widely used to manufacture versatile materials with specific mechanical and biological properties. The assembly of tropoelastin into elastic fibers or biomaterials is crucially influenced by key submolecular regions and specific residues within these domains. In this work, we identify the functional contributions of two rarely occurring negatively charged residues, glutamate 345 in domain 19 and glutamate 414 in domain 21, in jointly maintaining the native conformation of the tropoelastin hinge, bridge and foot regions. Alanine substitution of E345 and/or E414 variably alters the positioning and interactive accessibility of these regions, as illustrated by nanostructural studies and detected by antibody and cell probes. These structural changes are associated with a lower propensity for monomer coacervation, cross-linking into morphologically and functionally atypical hydrogels, and markedly impaired and abnormal elastic fiber formation. Our work indicates the crucial significance of both E345 and E414 residues in modulating specific local structure and higher-order assembly of human tropoelastin.
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Affiliation(s)
- Giselle
C. Yeo
- Charles Perkins Centre, School of Life and
Environmental Sciences, School of Physics, Sydney Medical School, and Bosch Institute, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Clair Baldock
- Wellcome
Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine
and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Steven G. Wise
- Charles Perkins Centre, School of Life and
Environmental Sciences, School of Physics, Sydney Medical School, and Bosch Institute, The University of Sydney, Sydney, New South Wales 2006, Australia
- The
Heart Research Institute, 7 Eliza Street, Newtown, New South Wales 2050, Australia
| | - Anthony S. Weiss
- Charles Perkins Centre, School of Life and
Environmental Sciences, School of Physics, Sydney Medical School, and Bosch Institute, The University of Sydney, Sydney, New South Wales 2006, Australia
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3
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Yeo GC, Tarakanova A, Baldock C, Wise SG, Buehler MJ, Weiss AS. Subtle balance of tropoelastin molecular shape and flexibility regulates dynamics and hierarchical assembly. SCIENCE ADVANCES 2016; 2:e1501145. [PMID: 26998516 PMCID: PMC4795673 DOI: 10.1126/sciadv.1501145] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Accepted: 11/20/2015] [Indexed: 05/02/2023]
Abstract
The assembly of the tropoelastin monomer into elastin is vital for conferring elasticity on blood vessels, skin, and lungs. Tropoelastin has dual needs for flexibility and structure in self-assembly. We explore the structure-dynamics-function interplay, consider the duality of molecular order and disorder, and identify equally significant functional contributions by local and global structures. To study these organizational stratifications, we perturb a key hinge region by expressing an exon that is universally spliced out in human tropoelastins. We find a herniated nanostructure with a displaced C terminus and explain by molecular modeling that flexible helices are replaced with substantial β sheets. We see atypical higher-order cross-linking and inefficient assembly into discontinuous, thick elastic fibers. We explain this dysfunction by correlating local and global structural effects with changes in the molecule's assembly dynamics. This work has general implications for our understanding of elastomeric proteins, which balance disordered regions with defined structural modules at multiple scales for functional assembly.
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Affiliation(s)
- Giselle C. Yeo
- Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales 2006, Australia
- School of Molecular Bioscience, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Anna Tarakanova
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Clair Baldock
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Steven G. Wise
- The Heart Research Institute, Newtown, New South Wales 2050, Australia
| | - Markus J. Buehler
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Anthony S. Weiss
- Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales 2006, Australia
- School of Molecular Bioscience, The University of Sydney, Sydney, New South Wales 2006, Australia
- Bosch Institute, The University of Sydney, Sydney, New South Wales 2006, Australia
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4
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Pilecki B, Holm AT, Schlosser A, Moeller JB, Wohl AP, Zuk AV, Heumüller SE, Wallis R, Moestrup SK, Sengle G, Holmskov U, Sorensen GL. Characterization of Microfibrillar-associated Protein 4 (MFAP4) as a Tropoelastin- and Fibrillin-binding Protein Involved in Elastic Fiber Formation. J Biol Chem 2015; 291:1103-14. [PMID: 26601954 DOI: 10.1074/jbc.m115.681775] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Indexed: 11/06/2022] Open
Abstract
MFAP4 (microfibrillar-associated protein 4) is an extracellular glycoprotein found in elastic fibers without a clearly defined role in elastic fiber assembly. In the present study, we characterized molecular interactions between MFAP4 and elastic fiber components. We established that MFAP4 primarily assembles into trimeric and hexameric structures of homodimers. Binding analysis revealed that MFAP4 specifically binds tropoelastin and fibrillin-1 and -2, as well as the elastin cross-linking amino acid desmosine, and that it co-localizes with fibrillin-1-positive fibers in vivo. Site-directed mutagenesis disclosed residues Phe(241) and Ser(203) in MFAP4 as being crucial for type I collagen, elastin, and tropoelastin binding. Furthermore, we found that MFAP4 actively promotes tropoelastin self-assembly. In conclusion, our data identify MFAP4 as a new ligand of microfibrils and tropoelastin involved in proper elastic fiber organization.
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Affiliation(s)
- Bartosz Pilecki
- From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark
| | - Anne T Holm
- From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark
| | - Anders Schlosser
- From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark
| | - Jesper B Moeller
- From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark
| | | | | | - Stefanie E Heumüller
- the Center for Biochemistry, Faculty of Medicine and the Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
| | - Russell Wallis
- the Department of Infection, Immunity and Inflammation, and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN, United Kingdom, and
| | - Soren K Moestrup
- From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark, the Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, 5000 Odense C, Denmark
| | - Gerhard Sengle
- the Center for Biochemistry, Faculty of Medicine and the Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany
| | - Uffe Holmskov
- From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark
| | - Grith L Sorensen
- From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark,
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Yeo GC, Aghaei-Ghareh-Bolagh B, Brackenreg EP, Hiob MA, Lee P, Weiss AS. Fabricated Elastin. Adv Healthc Mater 2015; 4:2530-2556. [PMID: 25771993 PMCID: PMC4568180 DOI: 10.1002/adhm.201400781] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 02/09/2015] [Indexed: 12/18/2022]
Abstract
The mechanical stability, elasticity, inherent bioactivity, and self-assembly properties of elastin make it a highly attractive candidate for the fabrication of versatile biomaterials. The ability to engineer specific peptide sequences derived from elastin allows the precise control of these physicochemical and organizational characteristics, and further broadens the diversity of elastin-based applications. Elastin and elastin-like peptides can also be modified or blended with other natural or synthetic moieties, including peptides, proteins, polysaccharides, and polymers, to augment existing capabilities or confer additional architectural and biofunctional features to compositionally pure materials. Elastin and elastin-based composites have been subjected to diverse fabrication processes, including heating, electrospinning, wet spinning, solvent casting, freeze-drying, and cross-linking, for the manufacture of particles, fibers, gels, tubes, sheets and films. The resulting materials can be tailored to possess specific strength, elasticity, morphology, topography, porosity, wettability, surface charge, and bioactivity. This extraordinary tunability of elastin-based constructs enables their use in a range of biomedical and tissue engineering applications such as targeted drug delivery, cell encapsulation, vascular repair, nerve regeneration, wound healing, and dermal, cartilage, bone, and dental replacement.
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Affiliation(s)
- Giselle C. Yeo
- Charles Perkins Centre, The University of Sydney, NSW 2006, Australia
- School of Molecular Bioscience, The University of Sydney, NSW 2006, Australia
| | - Behnaz Aghaei-Ghareh-Bolagh
- Charles Perkins Centre, The University of Sydney, NSW 2006, Australia
- School of Molecular Bioscience, The University of Sydney, NSW 2006, Australia
| | - Edwin P. Brackenreg
- Charles Perkins Centre, The University of Sydney, NSW 2006, Australia
- School of Molecular Bioscience, The University of Sydney, NSW 2006, Australia
| | - Matti A. Hiob
- Charles Perkins Centre, The University of Sydney, NSW 2006, Australia
- School of Molecular Bioscience, The University of Sydney, NSW 2006, Australia
| | - Pearl Lee
- Charles Perkins Centre, The University of Sydney, NSW 2006, Australia
- School of Molecular Bioscience, The University of Sydney, NSW 2006, Australia
| | - Anthony S. Weiss
- Charles Perkins Centre, The University of Sydney, NSW 2006, Australia
- School of Molecular Bioscience, The University of Sydney, NSW 2006, Australia
- Bosch Institute, The University of Sydney, NSW 2006, Australia
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6
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Yeo GC, Baldock C, Wise SG, Weiss AS. A negatively charged residue stabilizes the tropoelastin N-terminal region for elastic fiber assembly. J Biol Chem 2014; 289:34815-26. [PMID: 25342751 PMCID: PMC4263881 DOI: 10.1074/jbc.m114.606772] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 10/21/2014] [Indexed: 01/16/2023] Open
Abstract
Tropoelastin is an extracellular matrix protein that assembles into elastic fibers that provide elasticity and strength to vertebrate tissues. Although the contributions of specific tropoelastin regions during each stage of elastogenesis are still not fully understood, studies predominantly recognize the central hinge/bridge and C-terminal foot as the major participants in tropoelastin assembly, with a number of interactions mediated by the abundant positively charged residues within these regions. However, much less is known about the importance of the rarely occurring negatively charged residues and the N-terminal coil region in tropoelastin assembly. The sole negatively charged residue in the first half of human tropoelastin is aspartate 72. In contrast, the same region comprises 17 positively charged residues. We mutated this aspartate residue to alanine and assessed the elastogenic capacity of this novel construct. We found that D72A tropoelastin has a decreased propensity for initial self-association, and it cross-links aberrantly into denser, less porous hydrogels with reduced swelling properties. Although the mutant can bind cells normally, it does not form elastic fibers with human dermal fibroblasts and forms fewer atypical fibers with human retinal pigmented epithelial cells. This impaired functionality is associated with conformational changes in the N-terminal region. Our results strongly point to the role of the Asp-72 site in stabilizing the N-terminal segment of human tropoelastin and the importance of this region in facilitating elastic fiber assembly.
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Affiliation(s)
- Giselle C Yeo
- From the School of Molecular Bioscience and Charles Perkins Centre, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Clair Baldock
- the Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Steven G Wise
- the Heart Research Institute, Sydney, New South Wales 2042, Australia, and the Sydney Medical School and
| | - Anthony S Weiss
- From the School of Molecular Bioscience and Charles Perkins Centre, University of Sydney, Sydney, New South Wales 2006, Australia, Bosch Institute, University of Sydney, Sydney, New South Wales 2006, Australia
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7
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Yamanaka M, Ishizaki Y, Nakagawa T, Taoka A, Fukumori Y. Purification and Characterization of Coacervate-Forming Cuticular Proteins from Papilio xuthus Pupae. Zoolog Sci 2013; 30:534-42. [DOI: 10.2108/zsj.30.534] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Masahiro Yamanaka
- Division of Life Sciences, Graduate school of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Yumi Ishizaki
- School of Natural System, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Taro Nakagawa
- School of Natural System, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Azuma Taoka
- School of Natural System, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Yoshihiro Fukumori
- School of Natural System, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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8
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Almine JF, Wise SG, Hiob M, Singh NK, Tiwari KK, Vali S, Abbasi T, Weiss AS. Elastin sequences trigger transient proinflammatory responses by human dermal fibroblasts. FASEB J 2013; 27:3455-65. [PMID: 23671273 DOI: 10.1096/fj.13-231787] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Following penetrating injury of the skin, a highly orchestrated and overlapping sequence of events helps to facilitate wound resolution. Inflammation is a hallmark that is initiated early, but the reciprocal relationship between cells and matrix molecules that triggers and maintains inflammation is poorly appreciated. Elastin is enriched in the deep dermis of skin. We propose that deep tissue injury encompasses elastin damage, yielding solubilized elastin that triggers inflammation. As dermal fibroblasts dominate the deep dermis, this means that a direct interaction between elastin sequences and fibroblasts would reveal a proinflammatory signature. Tropoelastin was used as a surrogate for elastin sequences. Tropoelastin triggered fibroblast expression of the metalloelastase MMP-12, which is normally expressed by macrophages. MMP-12 expression increased 1056 ± 286-fold by 6 h and persisted for 24 h. Chemokine expression was more transient, as chemokine C-X-C motif ligand 8 (CXCL8), CXCL1, and CXCL5 transcripts increased 11.8 ± 2.6-, 10.2 ± 0.4-, and 8593 ± 996-fold, respectively, by 6-12 h and then decreased. Through the use of specific inhibitors and protein truncation, we found that transduction of the tropoelastin signal was mediated by the fibroblast elastin binding protein (EBP). In silico modeling using a predictive computational fibroblast model confirmed the up-regulation, and simulations revealed PKA as a key part of the signaling circuit. We tested this prediction with 1 μM PKA inhibitor H-89 and found that 2 h of exposure correspondingly reduced expression of MMP-12 (63.9±12.3%) and all chemokine markers, consistent with the levels seen with EBP inhibition, and validated PKA as a novel node and druggable target to ameliorate the proinflammatory state. A separate trigger that utilized C-terminal RKRK of tropoelastin reduced marker expression to 65.0-76.5% and suggests the parallel involvement of integrin αVβ3. We propose that the solubilization of elastin as a result of dermal damage leads to rapid chemokine up-regulation by fibroblasts that is quenched when exposed elastin is removed by MMP-12.
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Affiliation(s)
- Jessica F Almine
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
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9
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Yeo GC, Baldock C, Tuukkanen A, Roessle M, Dyksterhuis LB, Wise SG, Matthews J, Mithieux SM, Weiss AS. Tropoelastin bridge region positions the cell-interactive C terminus and contributes to elastic fiber assembly. Proc Natl Acad Sci U S A 2012; 109:2878-83. [PMID: 22328151 PMCID: PMC3286909 DOI: 10.1073/pnas.1111615108] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The tropoelastin monomer undergoes stages of association by coacervation, deposition onto microfibrils, and cross-linking to form elastic fibers. Tropoelastin consists of an elastic N-terminal coil region and a cell-interactive C-terminal foot region linked together by a highly exposed bridge region. The bridge region is conveniently positioned to modulate elastic fiber assembly through association by coacervation and its proximity to dominant cross-linking domains. Tropoelastin constructs that either modify or remove the entire bridge and downstream regions were assessed for elastogenesis. These constructs focused on a single alanine substitution (R515A) and a truncation (M155n) at the highly conserved arginine 515 site that borders the bridge. Each form displayed less efficient coacervation, impaired hydrogel formation, and decreased dermal fibroblast attachment compared to wild-type tropoelastin. The R515A mutant protein additionally showed reduced elastic fiber formation upon addition to human retinal pigmented epithelium cells and dermal fibroblasts. The small-angle X-ray scattering nanostructure of the R515A mutant protein revealed greater conformational flexibility around the bridge and C-terminal regions. This increased flexibility of the R515A mutant suggests that the tropoelastin R515 residue stabilizes the structure of the bridge region, which is critical for elastic fiber assembly.
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Affiliation(s)
- Giselle C Yeo
- School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia
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10
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Yeo GC, Keeley FW, Weiss AS. Coacervation of tropoelastin. Adv Colloid Interface Sci 2011; 167:94-103. [PMID: 21081222 DOI: 10.1016/j.cis.2010.10.003] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 10/13/2010] [Accepted: 10/15/2010] [Indexed: 12/14/2022]
Abstract
The coacervation of tropoelastin represents the first major stage of elastic fiber assembly. The process has been modeled in vitro by numerous studies, initially with mixtures of solubilized elastin, and subsequently with synthetic elastin peptides that represent hydrophobic repeat units, isolated hydrophobic domains, segments of alternating hydrophobic and cross-linking domains, or the full-length monomer. Tropoelastin coacervation in vitro is characterized by two stages: an initial phase separation, which involves a reversible inverse temperature transition of monomer to n-mer; and maturation, which is defined by the irreversible coalescence of coacervates into large species with fibrillar structures. Coacervation is an intrinsic ability of tropoelastin. It is primarily influenced by the number, sequence, and contextual arrangement of hydrophobic domains, although hydrophilic sequences can also affect the behavior of the hydrophobic domains and thus affect coacervation. External conditions including ionic strength, pH, and temperature also directly influence the propensity of tropoelastin to self-associate. Coacervation is an endothermic, entropically-driven process driven by the cooperative interactions of hydrophobic domains following destabilization of the clathrate-like water shielding these regions. The formation of such assemblies is believed to follow a helical nucleation model of polymerization. Coacervation is closely associated with conformational transitions of the monomer, such as increased β-structures in hydrophobic domains and α-helices in cross-linking domains. Tropoelastin coacervation in vivo is thought to mainly involve the central hydrophobic domains. In addition, cell-surface glycosaminoglycans and microfibrillar proteins may regulate the process. Coacervation is essential for progression to downstream elastogenic stages, and impairment of the process can result in elastin haploinsufficiency disorders such as supravalvular aortic stenosis.
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Baldock C, Oberhauser AF, Ma L, Lammie D, Siegler V, Mithieux SM, Tu Y, Chow JYH, Suleman F, Malfois M, Rogers S, Guo L, Irving TC, Wess TJ, Weiss AS. Shape of tropoelastin, the highly extensible protein that controls human tissue elasticity. Proc Natl Acad Sci U S A 2011; 108:4322-7. [PMID: 21368178 PMCID: PMC3060269 DOI: 10.1073/pnas.1014280108] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Elastin enables the reversible deformation of elastic tissues and can withstand decades of repetitive forces. Tropoelastin is the soluble precursor to elastin, the main elastic protein found in mammals. Little is known of the shape and mechanism of assembly of tropoelastin as its unique composition and propensity to self-associate has hampered structural studies. In this study, we solve the nanostructure of full-length and corresponding overlapping fragments of tropoelastin using small angle X-ray and neutron scattering, allowing us to identify discrete regions of the molecule. Tropoelastin is an asymmetric coil, with a protruding foot that encompasses the C-terminal cell interaction motif. We show that individual tropoelastin molecules are highly extensible yet elastic without hysteresis to perform as highly efficient molecular nanosprings. Our findings shed light on how biology uses this single protein to build durable elastic structures that allow for cell attachment to an appended foot. We present a unique model for head-to-tail assembly which allows for the propagation of the molecule's asymmetric coil through a stacked spring design.
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Affiliation(s)
- Clair Baldock
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Andres F. Oberhauser
- Department of Neuroscience and Cell Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555
| | - Liang Ma
- Department of Neuroscience and Cell Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555
| | - Donna Lammie
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4LU, United Kingdom
| | - Veronique Siegler
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4LU, United Kingdom
| | - Suzanne M. Mithieux
- School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia
| | - Yidong Tu
- School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia
| | - John Yuen Ho Chow
- School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia
| | - Farhana Suleman
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Marc Malfois
- Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Sarah Rogers
- ISIS Science and Technology Facilities Council, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 0QX, United Kingdom; and
| | - Liang Guo
- BioCAT, Center for Synchrotron Radiation Research and Instrumentation and Department of Biological, Chemical, and Physical Sciences, 3101 South Dearborn Street, Illinois Institute of Technology, Chicago, IL 60616
| | - Thomas C. Irving
- BioCAT, Center for Synchrotron Radiation Research and Instrumentation and Department of Biological, Chemical, and Physical Sciences, 3101 South Dearborn Street, Illinois Institute of Technology, Chicago, IL 60616
| | - Tim J. Wess
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4LU, United Kingdom
| | - Anthony S. Weiss
- School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia
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12
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Holst J, Watson S, Lord MS, Eamegdool SS, Bax DV, Nivison-Smith LB, Kondyurin A, Ma L, Oberhauser AF, Weiss AS, Rasko JEJ. Substrate elasticity provides mechanical signals for the expansion of hemopoietic stem and progenitor cells. Nat Biotechnol 2010; 28:1123-8. [PMID: 20890282 DOI: 10.1038/nbt.1687] [Citation(s) in RCA: 219] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Accepted: 09/07/2010] [Indexed: 02/07/2023]
Abstract
Surprisingly little is known about the effects of the physical microenvironment on hemopoietic stem and progenitor cells. To explore the physical effects of matrix elasticity on well-characterized primitive hemopoietic cells, we made use of a uniquely elastic biomaterial, tropoelastin. Culturing mouse or human hemopoietic cells on a tropoelastin substrate led to a two- to threefold expansion of undifferentiated cells, including progenitors and mouse stem cells. Treatment with cytokines in the presence of tropoelastin had an additive effect on this expansion. These biological effects required substrate elasticity, as neither truncated nor cross-linked tropoelastin reproduced the phenomenon, and inhibition of mechanotransduction abrogated the effects. Our data suggest that substrate elasticity and tensegrity are important mechanisms influencing hemopoietic stem and progenitor cell subsets and could be exploited to facilitate cell culture.
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Affiliation(s)
- Jeff Holst
- Gene & Stem Cell Therapy Program, Centenary Institute, Camperdown, New South Wales, Australia
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13
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Muiznieks LD, Weiss AS, Keeley FW. Structural disorder and dynamics of elastin. Biochem Cell Biol 2010; 88:239-50. [PMID: 20453927 DOI: 10.1139/o09-161] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elastin is a self-assembling, extracellular-matrix protein that is the major provider of tissue elasticity. Here we review structural studies of elastin from over four decades, and draw together evidence for solution flexibility and conformational disorder that is inherent in all levels of structural organization. The characterization of disorder is consistent with an entropy-driven mechanism of elastic recoil. We conclude that conformational disorder is a constitutive feature of elastin structure and function.
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Affiliation(s)
- Lisa D Muiznieks
- Research Institute, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada.
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14
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Wachi H, Sato F, Nakazawa J, Nonaka R, Szabo Z, Urban Z, Yasunaga T, Maeda I, Okamoto K, Starcher BC, Li DY, Mecham RP, Seyama Y. Domains 16 and 17 of tropoelastin in elastic fibre formation. Biochem J 2007; 402:63-70. [PMID: 17037986 PMCID: PMC1783983 DOI: 10.1042/bj20061145] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Naturally occurring mutations are useful in identifying domains that are important for protein function. We studied a mutation in the elastin gene, 800-3G>C, a common disease allele for SVAS (supravalvular aortic stenosis). We showed in primary skin fibroblasts from two different SVAS families that this mutation causes skipping of exons 16-17 and results in a stable mRNA. Tropoelastin lacking domains 16-17 (Delta16-17) was synthesized efficiently and secreted by transfected retinal pigment epithelium cells, but showed the deficient deposition into the extracellular matrix compared with normal as demonstrated by immunofluorescent staining and desmosine assays. Solid-phase binding assays indicated normal molecular interaction of Delta16-17 with fibrillin-1 and fibulin-5. However, self-association of Delta16-17 was diminished as shown by an elevated coacervation temperature. Moreover, negative staining electron microscopy confirmed that Delta16-17 was deficient in forming fibrillar polymers. Domain 16 has high homology with domain 30, which can form a beta-sheet structure facilitating fibre formation. Taken together, we conclude that domains 16-17 are important for self-association of tropoelastin and elastic fibre formation. This study is the first to discover that domains of elastin play an essential role in elastic fibre formation by facilitating homotypic interactions.
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Affiliation(s)
- Hiroshi Wachi
- Department of Clinical Chemistry, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
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15
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Gheduzzi D, Guerra D, Bochicchio B, Pepe A, Tamburro AM, Quaglino D, Mithieux S, Weiss AS, Pasquali Ronchetti I. Heparan sulphate interacts with tropoelastin, with some tropoelastin peptides and is present in human dermis elastic fibers. Matrix Biol 2005; 24:15-25. [PMID: 15748998 DOI: 10.1016/j.matbio.2004.12.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Revised: 10/14/2004] [Accepted: 12/10/2004] [Indexed: 11/19/2022]
Abstract
A number of reports point to the presence of proteoglycans and/or glycosaminoglycans within elastic fibers in normal and in pathological conditions. We present data that heparan sulphate (HS)-containing proteoglycans are associated with normal elastic fibers in human dermis and that isolated HS chains interact in vitro with recombinant tropoelastin and with peptides encoded by distinct exons of the human tropoelastin gene (EDPs). By immunocytochemistry, HS chains were identified as associated with the amorphous elastin component in the human dermis and remained associated with the residual elastin in the partially degenerated fibers of old subjects. HS appeared particularly concentrated in the mineralization front of elastic fibers in the dermis of patients affected by pseudoxanthoma elasticum (PXE). In in vitro experiments, HS induced substantial changes in the coacervation temperature and in the aggregation properties of recombinant tropoelastin and of synthetic peptides (EDPs) corresponding to sequences encoded by exons 18, 20, 24 and 30 of the human tropoelastin gene. In particular, HS modified the coacervation temperature and favoured the aggregation into ordered structures of tropoelastin molecules and of EDPs 18, 20 and 24, but not of EDP30. These data strongly indicate that HS-elastin interactions may play a role in tissue elastin fibrogenesis as well as modulating elastin stability with time and in diseases.
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Affiliation(s)
- Dealba Gheduzzi
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41100-Modena, Italy
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Clarke AW, Weiss AS. Microfibril-associated glycoprotein-1 binding to tropoelastin: multiple binding sites and the role of divalent cations. ACTA ACUST UNITED AC 2004; 271:3085-90. [PMID: 15233806 DOI: 10.1111/j.1432-1033.2004.04246.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microfibrils and elastin are major constituents of elastic fibers, the assembly of which is dictated by multimolecular interactions. Microfibril-associated glycoprotein-1 (MAGP-1) is a microfibrillar component that interacts with the soluble elastin precursor, tropoelastin. We describe here the adaptation of a solid-phase binding assay that defines the effect of divalent cations on the interactions between MAGP-1 and tropoelastin. Using this assay, a strong calcium-dependent interaction was demonstrated, with a dissociation constant of 2.8 +/- 0.3 nm, which fits a single-site binding model. Manganese and magnesium bestowed a weaker association, and copper did not facilitate the protein interactions. Three constructs spanning tropoelastin were used to quantify their relative contributions to calcium-dependent MAGP-1 binding. Binding to a construct spanning a region from the N-terminus to domain 18 followed a single-site binding model with a dissociation constant of 12.0 +/- 2.2 nm, which contrasted with the complex binding behavior observed for fragments spanning domains 17-27 and domain 27 to the C-terminus. To further elucidate binding sites around the kallikrein cleavage site of domains 25/26, MAGP-1 was presented with constructs containing C-terminal deletions within the region. Construct M1659, which spans a region from the N-terminus of tropoelastin to domain 26, inclusive, bound MAGP-1 with a dissociation constant of 9.7 +/- 2.0 nm, which decreased to 4.9 +/- 1.0 nm following the removal of domain 26 (M155n), thus displaying only half the total capacity to bind MAGP-1. These results demonstrate that MAGP-1 is capable of cumulative binding to distinct regions on tropoelastin, with different apparent dissociation constants and different amounts of bound protein.
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Affiliation(s)
- Adam W Clarke
- School of Molecular and Microbial Biosciences, University of Sydney, NSW, Australia
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17
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Miao M, Bellingham CM, Stahl RJ, Sitarz EE, Lane CJ, Keeley FW. Sequence and structure determinants for the self-aggregation of recombinant polypeptides modeled after human elastin. J Biol Chem 2003; 278:48553-62. [PMID: 14500713 DOI: 10.1074/jbc.m308465200] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Elastin is a polymeric structural protein that imparts the physical properties of extensibility and elastic recoil to tissues. The mechanism of assembly of the tropoelastin monomer into the elastin polymer probably involves extrinsic protein factors but is also related to an intrinsic capacity of elastin for ordered assembly through a process of hydrophobic self-aggregation or coacervation. Using a series of simple recombinant polypeptides based on elastin sequences and mimicking the unusual alternating domain structure of native elastin, we have investigated the influence of sequence motifs and domain structures on the propensity of these polypeptides for coacervation. The number of hydrophobic domains, their context in the alternating domain structure of elastin, and the specific nature of the hydrophobic domains included in the polypeptides all had major effects on self-aggregation. Surprisingly, in polypeptides with the same number of domains, propensity for coacervation was inversely related to the mean Kyte-Doolittle hydropathy of the polypeptide. Point mutations designed to increase the conformational flexibility of hydrophobic domains had the unexpected effect of suppressing coacervation and promoting formation of amyloid-like fibers. Such simple polypeptides provide a useful model system for understanding the relationship between sequence, structure, and mechanism of assembly of polymeric elastin.
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Affiliation(s)
- Ming Miao
- Research Institute, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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Toonkool P, Jensen SA, Maxwell AL, Weiss AS. Hydrophobic domains of human tropoelastin interact in a context-dependent manner. J Biol Chem 2001; 276:44575-80. [PMID: 11564742 DOI: 10.1074/jbc.m107920200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tropoelastin is the soluble precursor of elastin, the major component of the extracellular elastic fiber. Tropoelastin undergoes self-association via an inverse temperature transition termed coacervation, which is a crucial step in elastogenesis. Coacervation of tropoelastin takes place through multiple intermolecular interactions of its hydrophobic domains. Previous work has implicated those hydrophobic domains located near the center of the polypeptide as playing a dominant role in coacervation. Short constructs of domains 18, 20, 24, and a mutated form of domain 26 were largely disordered at 20 degrees C but displayed increased order on heating that was consistent with the formation of beta-structures. However, their conformational transitions were not sensitive to physiological temperature in contrast to the observed behavior of the native domain 26. A polypeptide consisting of domains 17-27 of tropoelastin coacervated at temperatures above 60 degrees C, whereas individually expressed hydrophobic regions were not capable of coacervation. We conclude that coacervation depends on the hydrophobicity of the molecule and, by inference, the number of hydrophobic domains. Tropoelastin mutants were constructed to contain a Pro --> Ala mutation in domain 26, separate deletions of domains 18 and 26, and a displacement of domain 26. These constructs displayed unequal capacities for coacervation, even when they contained the same number of hydrophobic regions and comparable levels of secondary structure. Thus, the capability for coacervation is determined by contributions from individual hydrophobic domains for which function should be considered in the context of their positions in the intact tropoelastin molecule.
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Affiliation(s)
- P Toonkool
- Department of Biochemistry, University of Sydney, Sydney, New South Wales 2006, Australia
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Jensen SA, Vrhovski B, Weiss AS. Domain 26 of tropoelastin plays a dominant role in association by coacervation. J Biol Chem 2000; 275:28449-54. [PMID: 10862774 DOI: 10.1074/jbc.m004265200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The temperature-dependent association of tropoelastin molecules through coacervation is an essential step in their assembly leading to elastogenesis. The relative contributions of C-terminal hydrophobic domains in coacervation were assessed. Truncated tropoelastins were constructed with N termini positioned variably downstream of domain 25. The purified proteins were assessed for their ability to coacervate. Disruption to domain 26 had a substantial effect and abolished coacervation. Circular dichroism spectroscopy of an isolated peptide comprising domain 26 showed that it undergoes a structural transition to a state of increased order with increasing temperature. Protease mapping demonstrated that domain 26 is flanked by surface sites and is likely to be in an exposed position on the surface of the tropoelastin molecule. These results suggest that the hydrophobic domain 26 is positioned to play a dominant role in the intermolecular interactions that occur during coacervation.
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Affiliation(s)
- S A Jensen
- Department of Biochemistry, G08, University of Sydney, Sydney NSW 2006, Australia
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