They are ubiquitous across most vertebrates other than lower vertebrates such as species from the superclass Agnatha (jawless fish) (Debelle and Tamburro, 1999). 281, 2375723765. Bull. The last 17 amino acid residues of the C-terminus of domain 36 are also implicated in HS interactions; the last four residues are Arg-Lys-Arg-Lys and are positively charged at physiological pH which provides a charged cluster capable of binding negatively charged HS (Broekelmann et al., 2005). 26, 115124. (2017). Exp. For example, their inclusion in peptides derived from hydrophobic domains confers decreased times taken for self-assembly, most likely due to their favorable interaction with aqueous solvent (Miao et al., 2003). Biomacromolecules 20, 11781189. J. Biol. Coacervation optimally occurs at physiological temperature, however, in vitro coacervation can also occur at lower temperatures depending on experimental conditions and the choice of tropoelastin isoform or derivative (Yeo et al., 2011). Due to the lack of a full-atomistic structure, a number of elastin derivatives, including isolated tropoelastin domains (Toonkool et al., 2001; Mackay et al., 2005; Dyksterhuis et al., 2007; Dyksterhuis and Weiss, 2010) and synthetic elastin-derived peptides (EDPs) (Luan et al., 1990; Tamburro et al., 1992; Kentsis and Sosnick, 1998; Kumashiro et al., 2006; Reichheld et al., 2014, 2017; Muiznieks et al., 2015; MacEwan et al., 2017; Tarakanova et al., 2017) have been studied to understand tropoelastins domain level properties. Elastins subunit, tropoelastin, is a soluble 6070 kDa protein which has been intensely studied over the past three decades. Detailed Description: 28, 432441. doi: 10.1093/protein/13.11.739, Roberts, S., Dzuricky, M., and Chilkoti, A. doi: 10.1016/0005-2795(73)90368-1, Franzblau, C., Faris, B., and Papaioannou, R. (1969). doi: 10.1021/acs.biomac.6b01759, Mackay, J. P., Muiznieks, L. D., Toonkool, P., and Weiss, A. S. (2005). 98, 416. doi: 10.1007/978-3-319-71530-8_13-1, Wen, Q., Mithieux, S. M., and Weiss, A. S. (2020). 278, 4855348562. Elastagen has received investment from an international syndicate of venture groups including AmorePacific Ventures, Brandon Capital, Cell Innovation Partners, Cicada Innovations, GBS Ventures, Korea Investment Partners and the Wellcome Trust. In vitro elastogenesis: instructing human vascular smooth muscle cells to generate an elastic fiber-containing extracellular matrix scaffold. Integrin alpha v beta 3 binds a unique non-RGD site near the C-terminus of human tropoelastin. Integrins canonically bind proteins containing Arg-Glu-Asp motifs, but this sequence is not found in tropoelastin (Lee et al., 2014). It has been postulated that the interaction between tropoelastin and cell surface proteoglycans is part of the assembly process of elastin before it is deposited on microfibrils. For more information, visit Allergans website atwww.Allergan.com. U.S.A. 108, 43224327. Four days after a heart attack, purified tropoelastin was injected into the heart. J. Therm. A comprehensive map of human elastin cross-linking during elastogenesis. U.S.A. 84, 56805684. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). Elastagens revolutionary technology is based on recombinant human tropoelastin, the precursor of elastin which is a key component of youthful skin. 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. (1973). (1977). Elastogenesis occurs during replacement fibrosis in human heart disease and can be accelerated in vitro via tropoelastin treatment. Elastin as a random-network elastomer: a mechanical and optical analysis of single elastin fibers. The hydrophobic domains contain aliphatic amino acids with proline variations that provide flexibility and the ability to assemble into higher order structures. 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. 31, 261272. 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). For example, the highly flexible domains 25 that were noted to generate a twisting motion in N-terminus, were positioned beside domain 6, a relatively immobile region that may assist in stabilizing the subsequent regions. Although alanine tracts within other proteins are predisposed to -helix formation (Yang and Honig, 1995; Avbelj, 2000), high helical content within tropoelastins KA domains was primarily demonstrated to persist in solvents that stabilize secondary structure, such as trifluoroethanol, rather than aqueous solution (Luo and Baldwin, 1997; Tamburro et al., 2006). Sci. Sequences and domain structures of mammalian, avian, amphibian and teleost tropoelastins: clues to the evolutionary history of elastins. Possible role in nucleated assembly. doi: 10.1002/ajmg.1320340115, Indik, Z., Yeh, H., Ornstein-Goldstein, N., Sheppard, P., Anderson, N., Rosenbloom, J. C., et al. Marked longevity of human lung parenchymal elastic fibers deduced from prevalence of D-aspartate and nuclear weapons-related radiocarbon. doi: 10.1021/bi00835a022, Lockhart-Cairns, M. P., Newandee, H., Thomson, J., Weiss, A. S., Baldock, C., and Tarakanova, A. Fluorescently labelled mesenchymal stem cells growing on tropoelastin. Fabricating organized elastin in vascular grafts. Biopolymers 20, 12471260. Matrix Biol. More surprisingly, tropoelastins cross-linking domains are also capable of similar transitions between ordered and disordered structures. Foster, J. B., Broekelmann, T. J., et al. J. Biochem. KA domains were initially thought to form -helices and poly-proline II helices (PPII) due to the presence of cross-links which require a lysine arrangement that was postulated to be achieved via -helical configuration (Brown-Augsburger et al., 1995). doi: 10.1016/j.matbio.2006.09.011, Miao, M., Reichheld, S. E., Muiznieks, L. D., Huang, Y., and Keeley, F. W. (2013). doi: 10.1016/j.biomaterials.2017.01.041, Tarakanova, A., Ozsvar, J., Weiss, A. S., and Buehler, M. J. doi: 10.1007/978-1-4684-9093-0_25, Scandolera, A., Odoul, L., Salesse, S., Guillot, A., Blaise, S., Kawecki, C., et al. Elastic fibers are an important component of the extracellular matrix, providing stretch, resilience, and cell interactivity to a broad range of elastic tissues. 26, 524540. Lyophilized Powder. J. Pathol. II. (2016). Dominant driving factors of assembly were examined, including water, temperature and domain pair orientations. Mol. doi: 10.1016/j.jsb.2004.11.005, Muiznieks, L. D., Jensen, S. A., and Weiss, A. S. (2003). U.S.A. 116, 20422051. The hydrophobic domains have been extensively studied and are responsible for facilitating tropoelastins ability to self-assemble (Vrhovski et al., 1997; Toonkool et al., 2001). Chem. III. Matrix Biol. Chem. Insights into the structure and dynamics of lysyl oxidase propeptide, a flexible protein with numerous partners. Allergan's Medical Aesthetics business - a comprehensive portfolio of facial aesthetics, body contouring and plastic and regenerative medicine products - is expected to grow at an 8-10 percent CAGR from 2017 to 2025. The importance of tropoelastins flexibility during self-assembly has also been examined in the light of natural allysine modifications, which condense to give cross-links within mature elastin (discussed further in the following section) (Ozsvar et al., 2019). Developmental changes of tropoelastin synthesis by rat pulmonary fibroblasts and effects of dexamethasone. Tropoelastin interacts with cell-surface glycosaminoglycans via its COOH-terminal domain. Tropoelastins amino acid sequence predominantly consists of non-polar residues including glycine, valine, alanine, and proline (Debelle and Tamburro, 1999). doi: 10.1016/j.matbio.2009.10.003, Tu, Y., Wise, S. G., and Weiss, A. S. (2010). 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. 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. The N-terminal head caps an extended coil region that consists of domains 2-18. 19:e1800250. Assembly proceeds from a nucleation event and undergoes elongation in a step-wise manner to form a multimer which can occur in a head-to-tail fashion (Wise et al., 2014). Pediatr. Matrix Biol. Elastin synthesis and fiber assembly. Modeling has been verified using wet-bench methodologies, forming a robust suite of complementary methodologies that will undoubtedly become more prevalent for exploring the assembly of biological fibers over time. doi: 10.1021/acs.biomac.0c00546, Bochicchio, B., Floquet, N., Pepe, A., Alix, A. J., and Tamburro, A. M. (2004). Localizing alpha-helices in human tropoelastin: assembly of the elastin puzzle. 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. Elastin makes up the majority of elastic fibers and is formed by the hierarchical assembly of its monomer, tropoelastin. Furthermore, the SAXS/SANS structure has been mapped to an elastic network model with tunable stiffness to probe the role of tropoelastins flexibility in fiber assembly (Yeo et al., 2016). Adv. Conformational transitions of the cross-linking domains of elastin during self-assembly. Latent TGF- binding protein 4 promotes elastic fiber assembly by interacting with fibulin-5. (2006). (1981). Mater. Chem. 624, 137146. Biosci. The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. Cellular expression of tropoelastin mRNA splice variants. Sci. (2007). Domains 17-27 of tropoelastin contain key regions of contact for coacervation and contain an unusual turn-containing crosslinking domain. This suggests a high level of conformational sampling during this phase of coacervation, indicating that the flexibility of tropoelastin plays a key role in assembly that may persist, to some extent, into later stages of assembly (Reichheld et al., 2020). doi: 10.1006/excr.1995.1321, Hinek, A., and Rabinovitch, M. (1994). These remarkable properties arise from its sequence and structure, which render tropoelastin structurally highly flexible but not disordered (Tarakanova et al., 2018). Chem. (2019). It's a stretchy protein that resembles a rubber band it can stretch out (extend) and shrink back (recoil). Anal. The most crucial of these properties is the ability to undergo many stretch-recoil cycles whilst maintaining the structural and functional integrity of elastic tissues over an organisms lifetime. doi: 10.1074/jbc.M113.533893, Reiersen, H., and Rees, A. R. (2000). J. Mol. 284, 22162230. J. Med. The ERC binds elastin derived peptides, which are the product of proteolytic activity of soluble and insoluble elastin by various elastases. For this injection, the researchers used a new . Tropoelastin is a unique protein with biochemical and physical properties that allow it to rapidly self-assemble into fibrous structures. Ann. The alignment of these three domains indicates that at least two tropoelastin molecules are required to form this tetrafunctional cross-link, thus, giving rise to the head-to-tail model of assembly involving the growth of a linear chain that can assemble laterally to form sheets and eventually form spherules (Baldock et al., 2011). [Epub ahead of print]. 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. Domains 12 to 16 of tropoelastin promote cell attachment and spreading through interactions with glycosaminoglycan and integrins alphaV and alpha5beta1. Coacervation characteristics of recombinant human tropoelastin. doi: 10.1002/bip.22663, Murata, K., and Wolf, M. (2018). Engineering a highly elastic human protein-based sealant for surgical applications. The coacervate is made insoluble by irreversible crosslinking. Powered by Madgex Job Board Software. Trends Biotechnol. Specific instructions are found in the Directions for Use. 10, 15321541. Total synthesis and expression in Escherichia coli of a gene encoding human tropoelastin. 3, 28322844. Unlike hydrophobic domains, cross-linking domains in isolation are unable to self-assemble; thus, they have been studied in the context of the cross-linking of elastin-derived biomaterials (Annabi et al., 2017; Yue et al., 2017). 289, 489492. Tropoelastin interacts with microfibril components including fibrillin-1, fibulin-4, and -5, and other associated molecules such as latent transforming growth factor binding protein-4 (Visconti et al., 2003; McLaughlin et al., 2006; Urban et al., 2009; Yamauchi et al., 2010; Noda et al., 2013; Lockhart-Cairns et al., 2020). Elastic fiber formation: a dynamic view of extracellular matrix assembly using timer reporters. 10, 441454. This temperature is also known as the transition temperature. Fluor: Q4 Earnings Snapshot. 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. Elastin is heterogeneously cross-linked. Human ELN gives rise to a broad variety of splice isoforms, with alternative splicing being observed with exons 22, 23, 24, 26A, 32, and 33 (Fazio et al., 1988; Parks et al., 1992) that result in 13 known human isoforms of the mature tropoelastin protein (Reichheld et al., 2019). Elastin is the major component of elastic fibers, which are a major component of the tissue that supports the body's joints . Coacervation is an endothermic, entropically favorable process through which tropoelastin monomers self-assemble into higher order n-mer structures. 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). 278, 1849118498. J. Proc. Sequence variants of human tropoelastin affecting assembly, structural characteristics and functional properties of polymeric elastin in health and disease. Rep. 8, 116. Proc. doi: 10.1016/0304-4165(83)90357-4, Narayanan, A. S., Sandberg, L. B., Ross, R., and Layman, D. L. (1976). Chem. 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 . Hydrophobic domains of human tropoelastin interact in a context-dependent manner. Elastin binding protein (EBP) is a splice variant of -galactosidase, that recognizes the repetitive hydrophobic sequences (VGVAPG) of tropoelastin (Tajima et al., 1997). doi: 10.1074/jbc.M004265200, Kadler, K. E. (2017). 260, 32553258. Tropoelastin undergoes minimal energy loss during extension, similar to other polymers such as rubber and resilin (Elvin et al., 2005; Cordier et al., 2008; Baldock et al., 2011). Tropoelastin is typically used as a thin coating on tissue culture surfaces. The presence of tropoelastin spherules fusing to fibrils has been noted in native tissue, demonstrating marked similarities between in vitro and in vivo coacervation (Haust et al., 1965; Albert, 1972; Kozel et al., 2006). 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-1 interactions with heparin. J. A novel cell adhesion region in tropoelastin mediates attachment to integrin alphaVbeta5. Arch. Characterization of an unusual tropoelastin with truncated C-terminus in the frog. The study is designed to evaluate the efficacy of two formulations of a cross-linked tropoelastin matrix given the product codes ELAPR002f (collectively referred to as ELAPR or ELAPR002) for the treatment of rolling atrophic acne scars when administered as intradermal implants. doi: 10.1074/jbc.M507309200, Brown-Augsburger, P., Tisdale, C., Broekelmann, T., Sloan, C., and Mecham, R. P. (1995). 9:eaai7466. Proline-poor hydrophobic domains modulate the assembly and material properties of polymeric elastin. J. Biol. 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). Elastagen's technology is based on human tropoelastin . Elastagen was one of the inaugural recipients of MDF funding in 2013 and will be the first to successfully repay the funding amount. In addition to the RKRK sequence, domain 36 contains tropoelastins sole two cysteines and only disulfide bond. Sci. Commun. J. Exp. Instead, tropoelastin domains 1418 and 36 (RKRK sequence) have been found to bind to both integrins. (2009). 27, 441450. The stiffness that arose due to amino acid substitutions partially determined resultant secondary structure which, in turn, impacted assembly (Prhashanna et al., 2019). 432, 57365751. Unsubstituted models are also critical to understanding self-assembly. 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. Med. A., Gray, W. R., and Franzblau, C. (1973). Synthesis and properties of crosslinked recombinant pro-resilin. U.S.A. 110, 28522857. doi: 10.1074/jbc.M212715200, Kumashiro, K. K., Ho, J. P., Niemczura, W. P., and Keeley, F. W. (2006). 10 Endothelial cells, vascular smooth muscle cells, and adventitial fibroblasts produce tropoelastin during the late 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. However, there are aspects of this model that warrant further investigation. FEBS J. Struct. Albert, E. N. (1972). (2011). However, higher resolution data were required to map out its elusive properties and performance within a hierarchical assembly (Tarakanova et al., 2018; Ozsvar et al., 2019). Tropoelastins C-terminal domain 36 (yellow) does not fall into either category as it contains a distinct sequence capped with a Gly-Arg-Lys-Arg-Lys (GRKRK) motif and is primarily involved in cell interactions. The resultant bending motion rather than scissors-twist motion that stemmed from this stabilization highlights the mutants diminished flexibility as a key driver of impaired fiber assembly in cutis laxa (Tarakanova et al., 2018). 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. Tropoelastin cannot readily be prepared in quantity from natural sources and this has limited research in several important areas including structure/function relationships and fiber assembly.