On the cell surface, EBP forms a complex with protective protein/cathepsin A (PPCA) and neuraminidase-1 (Neu-1), giving rise to the ERC (Duca et al., 2007). The elastin receptor complex transduces signals through the catalytic activity of its Neu-1 subunit. doi: 10.1128/mcb.26.5.1700-1709.2006, Mecham, R. P. (1991). Self-healing and thermoreversible rubber from supramolecular assembly. Future investigations will allow the bridging of the gap between mesoscale simulations and microscopically observed coacervation (Clarke et al., 2006). PLoS One 7:e46130. The tropoelastin that Elastagen manufactures is an identical copy of what naturally occurs in human tissue, meaning the clinical application opportunities for this has tremendous potential . Matrix 12, 156162. By leveraging the advantages of computational models, such as elastic network models, full-atomistic models and coarse grained models, as depicted in Figure 2, the correlation between the structure, motions, and the functionality of tropoelastin have recently been explored in depth (Yeo et al., 2016; Tarakanova et al., 2018, 2019a). Allergan plc (NYSE: AGN), headquartered in Dublin, Ireland, is a bold, global biopharmaceutical company. Isolation and characterization of human elastin cDNAs, and age-associated variation in elastin gene expression in cultured skin fibroblasts. The smallest amino acid, glycine is known to promote flexibility within local structures due to lack of steric hindrance, whereas prolines restrictive sidechain inhibits conformational sampling and disrupts the formation of prolonged secondary structures (Roberts et al., 2015). Tropoelastins domains each arise from single exons of the ELN gene. doi: 10.1021/bi00835a022, Lockhart-Cairns, M. P., Newandee, H., Thomson, J., Weiss, A. S., Baldock, C., and Tarakanova, A. Mater. Water structure and elastin-like peptide aggregation. 589(19 Pt A), 24772486. Four days after a heart attack, purified tropoelastin was injected into the heart. Molecular model of human tropoelastin and implications of associated mutations. 10 Endothelial cells, vascular smooth muscle cells, and adventitial fibroblasts produce tropoelastin during the late Although there is no 3D structure for porcine tropoelastin, porcine tropoelastin differs from that of humans (Sandberg et al., 1977), leaving it unclear as to whether these domains align as expected in human tissue. Additionally, elastin is remarkably durable as it is primarily deposited during prenatal development and childhood, and is rarely synthesized during adulthood. Possible role in nucleated assembly. In addition, Elastagen has received significant support from Australian Federal Government grants and the NSW State Government Medical Devices Fund (MDF). (2020). Elastic fibers are composed of approximately 90% elastin, whilst the remaining components are primarily comprised of fibrillin glycoproteins (Mecham, 1991). Adv. Implications for microfibril and elastic fiber assembly. U.S.A. 108, 43224327. Unsubstituted models are also critical to understanding self-assembly. Proc. 10:034102. doi: 10.1088/1748-6041/10/3/034102, Hinek, A., Keeley, F. W., and Callahan, J. Differential scanning calorimetry studies of the inverse temperature transition of the polypentapeptide of elastin and its analogues. J. Exp. Molecular docking studies utilizing tropoelastin and the 3D structure of LOX1 (Vallet et al., 2018) may assist in our understanding as to whether the enzyme has a preference for modifying particular tropoelastin residues. Tropoelastins hydrophobic domains are primarily responsible for facilitating coacervation (Tamburro et al., 1992; Miao et al., 2003; Muiznieks et al., 2003). Acad. Figure 1. Elastic fibers are eventually formed after extensive cross-linking through a process termed maturation (Yeo et al., 2016). Overview of the computational and experimental methodologies that have recently contributed to our understanding of elastic fiber assembly. The N-terminal head caps an extended coil region that consists of domains 218. doi: 10.1016/j.matbio.2009.10.003, Tu, Y., Wise, S. G., and Weiss, A. S. (2010). Caterpillar | Caterpillar to Relocate Global Headquarters to Dallas However, there are aspects of this model that warrant further investigation. I thank the Elastagen team for their hard work and dedication in developing our innovative tropoelastin product pipeline and look forward to working with Allergan to take these products to market., Commenting on the transaction, Elastagens founding scientist Prof Anthony Weiss added:Our technology has come a long way from the lab bench at the University of Sydney towards developing products for patients around the world. 289, 1005710068. Proc. The lysines of domain 15 and 17 are believed to play key roles in this interaction. Healthcare Investment Banking - The Walden Group doi: 10.1371/journal.pone.0046130, Hedtke, T., Schrader, C. U., Heinz, A., Hoehenwarter, W., Brinckmann, J., Groth, T., et al. Below the coil is a flexible hinge region made up of domains 2024, which are directly adjacent to the bridge regions of domains 2526. Tropoelastin is a low complexity protein on both primary and secondary sequence levels. Tropoelastins flexibility does not allow it to pack into a crystal lattice and its size renders it too complex to assign atomic interactions using nuclear magnetic resonance (NMR) on a global level (Tamburro et al., 2003, 2006; Bochicchio et al., 2004; Pepe et al., 2008). (2009). (1965). Chem. Dominant driving factors of assembly were examined, including water, temperature and domain pair orientations. Biochemistry 8, 28332837. doi: 10.1126/scitranslmed.aai7466, PubMed Abstract | CrossRef Full Text | Google Scholar, Avbelj, F. (2000). Model. doi: 10.1016/j.str.2006.09.008, Rauscher, S., and Pomes, R. (2017). ACS Biomater. Chem. doi: 10.1126/sciadv.1501145, Yeo, G. C., and Weiss, A. S. (2019). Circ. Elastagen Pty Ltd, a clinical stage company developing medical device products based on recombinant tropoelastin, today announced that it has entered into a definitive agreement under which Allergan plc, a leading global biopharmaceutical company, has agreed to acquire Elastagen. Mol. Sci. How to Get LONGER Eyelashes - Guaranteed | NULASTIN Colloid Interface Sci. Elastin-like polypeptides as models of intrinsically disordered proteins. 624, 137146. 286, 35943610. The isoform-function theory is further reinforced by the presence of two different ELN genes within teleosts that are differentially expressed both spatially and temporally during development (Miao et al., 2007). 26, 115124. (2006). The cross-linking domains are enriched for either Lys-Pro (KP) or Lys-Ala (KA) motifs and form cross-links that link growing tropoelastin chains during elastogenesis; note that exon 6 encodes a KA domain. While tropoelastin is a flexible molecule, a combination of optical and structural analyses has defined key regions of the molecule that directly contribute to the elastomeric properties and control the cell interactions of the protein. doi: 10.1002/mabi.201800250, Tiedemann, K., Batge, B., Muller, P. K., and Reinhardt, D. P. (2001). Interactions of fibrillin-1 with heparin/heparan sulfate, implications for microfibrillar assembly. Biophys. We are very interested in the blend of biochemistry and cell biology, as well as the tissue engineering and regenerative medicine opportunities provided by this amazing elastic protein. The advantage of coarse-grained methodologies is that they allow for the simulation of timescales of large molecular systems on the order of microseconds, which are otherwise computationally infeasible with classical full-atomistic molecular dynamics. Tropoelastin, the soluble precursor to elastin, and the degradation products of fragmented elastic fibers also have important chemical signaling properties. 85, 593605. A. doi: 10.1021/bi00835a021, Gray, W. R., Sandberg, L. B., and Foster, J. The reduction in solvent accessible surface area of the mutant molecules suggests that the underlying mechanism for their altered self-assembly properties observed in experiments is due to less exposure of the appropriate hydrophobic domains required for coacervation. Res. Fluor: Q4 Earnings Snapshot | AP News Chem. doi: 10.1080/07391102.1992.10508661, Tamburro, A. M., Pepe, A., and Bochicchio, B. Chem. Importantly, the presence of fibrils indicates that the nanostructures formed during initial assembly contribute to the supramolecular structures that arise during both early (spherule) and later (fibril) stages of elastogenesis. doi: 10.1007/s004030050227, Tamburro, A. M., Bochicchio, B., and Pepe, A. 7:32. doi: 10.3389/fphar.2016.00032, Schmelzer, C. E. H., Heinz, A., Troilo, H., Lockhart-Cairns, M. P., Jowitt, T. A., Marchand, M. F., et al. Tropoelastin. J. Biol. FEBS J. Effect of peptide sequence on the LCST-like transition of elastin-like peptides and elastin-like peptidecollagen-like peptide conjugates: simulations and experiments. (1995). 275, 2844928454. Plus 2:100002. doi: 10.1016/j.mbplus.2019.03.001, Parks, W. C., Roby, J. D., Wu, L. C., and Grosso, L. E. (1992). Cryo-electron microscopy for structural analysis of dynamic biological macromolecules. 28, 432441. The SAXS/SANS global shape of tropoelastin (Baldock et al., 2011) has been used to validate the full-atomistic computational model of tropoelastin through a geometric and topological comparison (Tarakanova et al., 2018). (2003). Subtle balance of tropoelastin molecular shape and flexibility regulates dynamics and hierarchical assembly. This suggests the ERCs primary signal pathways are involved in wound recognition through fragments of elastin, where EDPs are formed as a result of elastic tissue damage. Coacervation of recombinant human tropoelastin is strongly influenced by the concentration of protein and NaCl and to a lesser extent on pH. Elastin biomaterials in dermal repair. Matrix Biol. The most commonly investigated isoform contains domain 26A and lacks domain 22, and is predominantly found in elastic tissues (Indik et al., 1987; Vrhovski et al., 1997). Cell Biol. February 14, 2018 Michael Patrini. doi: 10.1021/bi981641y, Kozel, B. FEBS Lett. (2017). After a period of collaboration with the Elastagen team, US biopharmaceutical giant Allergan acquired Elastagen in 2018 for over $350 million in total deal value. doi: 10.1016/0005-2795(73)90368-1, Franzblau, C., Faris, B., and Papaioannou, R. (1969). doi: 10.1016/j.matbio.2019.06.010, Reichheld, S. E., Muiznieks, L. D., Stahl, R., Simonetti, K., Sharpe, S., and Keeley, F. W. (2014). The compositions include a coalescence-controlling agent in the form of a polysaccharide or polysaccharide derivative, in an amount effective for providing the substance with the properties of flow, enabling injection. Thus, elastin is responsible, in great part, for the properties of elastic fibers. 432, 57365751. Chem. J. Pathol. Biochemistry of tropoelastin. In addition to interacting with tropoelastin, fibulin-4 and -5 are capable of also binding LOX and fibrillin-1 and, thus, have key roles in facilitating elastogenesis (Hinderer et al., 2015). 4, 508524. Foster, J. Tropoelastin has a defined shape in solution but paradoxically also displays a large percentage of flexible, disordered regions needed for molecular elasticity (4, 5).The tertiary structure of human tropoelastin represents an ensemble of elastic conformers (3, 6), yet occasional conserved sequence elements hint at requirements for functional demands in one or more key parts of this molecule (7 . Biophys. Tropoelastin promotes cell attachment and migration of several cell types including fibroblasts, endothelial cells and mesenchymal stem cells. Free energy determinants of secondary structure formation: I. alpha-Helices. Pharmacol. doi: 10.1006/jmbi.2000.3901, Baldock, C., Oberhauser, A. F., Ma, L., Lammie, D., Siegler, V., Mithieux, S. M., et al. J. Biol. An electron microscopic study. The smooth muscle cell. Reichheld, S. E., Muiznieks, L. D., Huynh, Q., Wang, N., Ing, C., Miao, M., et al. Amino acid conformational preferences and solvation of polar backbone atoms in peptides and proteins. Even after being able to produce recombinant tropoelastin at scales suited to characterization studies, traditional techniques have not yet produced an experimentally verified atomistic structure (Martin et al., 1995; Tarakanova and Buehler, 2013). doi: 10.1021/acs.biomac.6b01759, Mackay, J. P., Muiznieks, L. D., Toonkool, P., and Weiss, A. S. (2005). Together, these two properties can be tuned and exploited to give rise to an increasing number of novel biomaterials for tissue engineering and regenerative medicine, which have been recently reviewed elsewhere (Wang et al., 2020; Wen et al., 2020). Fabricating organized elastin in vascular grafts. 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. 11 Articles, This article is part of the Research Topic, Tropoelastin-Cell Receptor Interactions and Implications for Assembly, https://doi.org/10.3389/fbioe.2021.643110, Creative Commons Attribution License (CC BY). (2019). doi: 10.1074/jbc.M107920200, Tu, Y., and Weiss, A. S. (2010). No use, distribution or reproduction is permitted which does not comply with these terms. AW gratefully acknowledges NHMRC funding (Ref: 1195827). Res. doi: 10.1016/0014-4800(65)90015-8, He, D., Chung, M., Chan, E., Alleyne, T., Ha, K. C. H., Miao, M., et al. Tropoelastin is characterised by alternating hydrophobic and hydrophilic domains and is highly flexible. Cell Biol. doi: 10.1073/pnas.1812951116, Yue, K., Li, X., Schrobback, K., Sheikhi, A., Annabi, N., Leijten, J., et al. Allergan is focused on developing, manufacturing and commercializing branded pharmaceutical, device, biologic, surgical and regenerative medicine products for patients around the world. Biol. The elasticity of organs and tissues in vertebrates is due to the presence of elastin, and an insoluble protein whose soluble monomer, tropoelastin, is enzymatically cross-linked through -amino groups of lysine residues. The elastin receptor complex: a unique matricellular receptor with high anti-tumoral potential. Biochimie 86, 173178. doi: 10.1016/j.bbagen.2017.07.020, Myers, B., Dubick, M., Last, J. Coacervation characteristics of recombinant human tropoelastin Powered by Madgex Job Board Software. Biol. FEBS J. J. Biol. Vallet, S. D., Miele, A. E., Uciechowska-Kaczmarzyk, U., Liwo, A., Duclos, B., Samsonov, S. A., et al. (2018). 79, 277284. Similarly, a mutation model associated with cutis laxa, or loose skin disease (Hu et al., 2006), was found to exhibit higher stability compared with the wild-type molecule due to the increased longevity of its salt bridges (Hu et al., 2006; Tarakanova et al., 2018). Glycosaminoglycans (GAGs) are negatively charged, linear polysaccharides, which can be either sulfated [heparan sulfate (HS) or chondroitin sulfate] or non-sulfated (hyaluronic acid). The ERC binds elastin derived peptides, which are the product of proteolytic activity of soluble and insoluble elastin by various elastases. Developing elastic tissue. Collapse Section. Gene 154, 159166. Indeed, studies examining the consequences of domain insertions and deletions note changes in the intrinsic functionality of tropoelastin, corroborating the hypothesis that domain insertions and deletions result in altered tissue mechanics (Jensen et al., 2000; Kozel et al., 2003; Yeo et al., 2016; Miao et al., 2017). Elastin binding protein and FKBP65 modulate in vitro self-assembly of human tropoelastin. 280, 4093940947. 58, 270277. Such models could be used in conjunction with the full molecular model of tropoelastin to examine the self-assembly of discrete regions to understand the impacts of amino acid substitutions in disease. By probing mutations in computational studies that resolve the atomistic structure of the molecule, the deduction of mechanisms associated with changes to functional roles of specific domains has become feasible, and a connection between local structures and biological performance can be established (Figure 2; Tarakanova et al., 2018). 300, 13351359. Biotechnol. Acad. II. Cryo-electron microscopy is a rapidly developing method and likely to contribute to structural knowledge of tropoelastin. (2020). *Correspondence: Anthony S. Weiss, tony.weiss@sydney.edu.au, These authors have contributed equally to this work, Fibrous Assemblies: From Synthesis and Nanostructure Characterization to Materials Development and Application, Front. (2017). Tropoelastin is a unique protein with biochemical and physical properties that allow it to rapidly self-assemble into fibrous structures. In contrast, higher temperatures allow the breaking of the hydrogen bonds of the ordered water, dissipating the clathrate shells and permitting the association of the hydrophobic domains (Yeo et al., 2011). doi: 10.1074/jbc.M113.533893, Reiersen, H., and Rees, A. R. (2000). doi: 10.1016/j.matbio.2007.05.005, He, D., Miao, M., Sitarz, E. E., Muiznieks, L. D., Reichheld, S., Stahl, R. J., et al. Fibrillin-rich microfibrils of the extracellular matrix: ultrastructure and assembly. doi: 10.1046/j.1432-1327.1998.2580001.x, Wang, Z., Liu, L., Mithieux, S. M., and Weiss, A. S. (2020). Solving tropoelastins global structure (Baldock et al., 2011) allowed for 3D mapping on tropoelastin of the approximate locations of domains 10, 19, and 25, which were the first unequivocally cross-linked domains to be discovered (Brown-Augsburger et al., 1995). Interactions with these integrins on the surface of mesenchymal stem cells, either through surface bound or as soluble tropoelastin, promote MSC proliferation and phenotypic maintenance via FAK and PKB/AKT (Yeo and Weiss, 2019). Pharm. 149, 282289. J. Therm. Biophys. doi: 10.1074/jbc.M212715200, Kumashiro, K. K., Ho, J. P., Niemczura, W. P., and Keeley, F. W. (2006). Elastin makes up the majority of elastic fibers and is formed by the hierarchical assembly of its monomer, tropoelastin. This model revealed that tropoelastin maintains a canonical or average structure based on the distribution of its possible conformations in spite of its flexible nature (Figure 2), as well as the possible roles that local structures play in biological processes, specifically, elastogenesis (Tarakanova et al., 2019b). Biochemistry 37, 1461314622. Elastagens revolutionary recombinant human tropoelastin, is identical to that present in human tissue and has many clinical applications, including effective breakthrough treatments for acne scars, stretch marks, aesthetic skin repair and wound repair. Furthermore, as integrins are involved in the remodeling of the ECM (Bonnans et al., 2014), this is consistent with a model where the tropoelastin-integrin interaction forms part of the wound repair process. doi: 10.1016/j.matbio.2009.07.003, Mithieux, S. M., Wise, S. G., Raftery, M. J., Starcher, B., and Weiss, A. S. (2005). (2005). Matrix Biol. Initially, in vitro coacervation is characterized by the rapid aggregation of tropoelastin. Elastic fibers are present in the extracellular matrix (ECM) of vertebrate tissues, such as the skin, lungs, cardiovascular system, cartilage, and tendons. Characterization of an unusual tropoelastin with truncated C-terminus in the frog. Am. (2019). The N-terminal head caps an extended coil region that consists of domains 2-18. Biomacromolecules 21, 35233538. Production of recombinant human tropoelastin: Characterization and 207, 8796. doi: 10.1016/j.cis.2010.10.003, Yeo, G. C., Tarakanova, A., Baldock, C., Wise, S. G., Buehler, M. J., and Weiss, A. S. (2016). Micron 41, 268272. 1, 2 Elastogenesis, the process of elastin formation, mainly occurs during the fetal and early neonatal development of organs such as blood vessels, lungs, and skin. Tropoelastin #5052. (2006). (1995). Elastagens tropoelastin is identical to that present in human tissue, and has many potential clinical applications, including treatment for acne scars, stretch marks, aesthetic skin repair and surgical wound repair. (2019b). Elastic fibers provide tissues with mechanical resilience, durability, and cell interactivity, which support a diverse range of specialized functionality. Insights into the structure and behavior of tropoelastin have translated into increasingly sophisticated . Sci. More recently, it has been demonstrated that KA domains consist of random coil content prior to self-assembly and become more ordered as molecules aggregate, marrying the observations discussed above into a cohesive model within the context of assembly and the requirements of higher-order structures (Reichheld et al., 2014). HS, which is present on cell surface proteoglycans (syndecans and glypicans), interacts strongly with tropoelastin (Cain et al., 2005). Imaging 11:e007303. (1987). Tropoelastin bridge region positions the cell-interactive C terminus and contributes to elastic fiber assembly. It is likely that, as a general rule, integrin binding to tropoelastin is mediated via GAGs, which is facilitated by the repetition of tropoelastins primary sequence and the surface exposure of positively charged similar domains (Lee et al., 2017; Bochicchio et al., 2021). . Lyophilized Powder. Stiffness within the context of self-assembly has also been examined with both coarse grained and full-atomistic simulations using polypeptides derived from tropoelastins hydrophobic domains. 22, 109121. Am. Annabi, N., Zhang, Y. N., Assmann, A., Sani, E. S., Cheng, G., Lassaletta, A. D., et al. EBP plays two roles in the assembly of elastin. Dissection of human tropoelastin: solution structure, dynamics and self-assembly of the exon 5 peptide. This reflects the experimentally observed heterogeneity of cross-links in mature elastin, again giving weight to the hypothesis that the flexibility of tropoelastin is imperative for assembly (Schrader et al., 2018; Tarakanova et al., 2019a). 9:643110. doi: 10.3389/fbioe.2021.643110. Tropoelastin was revealed to be an asymmetric molecule with distinct N- and C-terminal regions that are respectively referred to as the head and foot of the molecule. Acta Histochem. These remarkable properties arise from its sequence and structure, which render tropoelastin structurally highly flexible but not disordered (Tarakanova et al., 2018).