Cross-linking domains can be subdivided into KP or KA domains, which denote the amino acids (proline or alanine, respectively) that are adjacent to the lysines (Figure 1). Eur. Biomacromolecules 20, 11781189. 3:100016. doi: 10.1016/j.mtbio.2019.100016, Tarakanova, A., Yeo, G. C., Baldock, C., Weiss, A. S., and Buehler, M. J. Crucially, these simulations revealed that self-assembly starts with a nucleation event and elongation proceeds via both globular and fibrillar structures (Tarakanova et al., 2019a). Parameter, Testing, and Method. Targeted modulation of tropoelastin structure and assembly. Elastagen's 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. doi: 10.1111/j.1432-1033.1997.00092.x, Vrhovski, B., and Weiss, A. S. (1998). 67-kD elastin-binding protein is a protective companion of extracellular insoluble elastin and intracellular tropoelastin. The first successful experiments to define the 3D envelope of tropoelastin utilized small angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) (Baldock et al., 2011). 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). Nat. Fibrillin-rich microfibrils of the extracellular matrix: ultrastructure and assembly. J. Ultrastruct. doi: 10.1046/j.1432-1327.1999.00891.x, Yamauchi, Y., Tsuruga, E., Nakashima, K., Sawa, Y., and Ishikawa, H. (2010). Increased cyclic GMP levels lead to a stimulation of elastin production in ligament fibroblasts that is reversed by cyclic AMP. Tropoelastin #5052. doi: 10.1126/scitranslmed.aai7466, PubMed Abstract | CrossRef Full Text | Google Scholar, Avbelj, F. (2000). Cellular activities are mediated through interactions between tropoelastin or EDPs and specific receptors on the cell surface. Developing elastic tissue. For this injection, the researchers used a new . (2017). Cell Biol. Poly (Val-Gly-Gly-Leu-Gly). This canonical computational structure was determined to be highly similar to the envelope found via SAXS/SANS, where both consist of an extended molecular body accompanied by a protruding foot (Baldock et al., 2011). Single nucleotide polymorphisms and domain/splice variants modulate assembly and elastomeric properties of human elastin. Detailed Description: 589(19 Pt A), 24772486. 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). Sci. (2019). For more information, visit Elastagens website atwww.elastagen.com. doi: 10.1073/pnas.1812951116, Yue, K., Li, X., Schrobback, K., Sheikhi, A., Annabi, N., Leijten, J., et al. doi: 10.1073/pnas.1215779110, Noguchi, A., Firsching, K., Kursar, J. D., and Reddy, R. (1990). The smooth muscle cell. However, there are aspects of this model that warrant further investigation. J. Biol. doi: 10.1111/febs.14114, Lent, R. W., Smith, B., Salcedo, L. L., Faris, B., and Franzblau, C. (1969). Chem. Elastin is highly hydrophobic, extensively cross-linked, and is assembled into elastic fibers in a dynamic process involving cells, cell surface receptors, and numerous elastic fiber . (2013). EBP plays two roles in the assembly of elastin. They can be categorized as either hydrophobic or cross-linking based on their functionality and amino acid content (Figure 1). doi: 10.1073/pnas.1111615108, Yeo, G. C., Baldock, C., Wise, S. G., and Weiss, A. S. (2017). Further down the molecule, the cell-interactive C-terminus was noted to be highly flexible, indicating that high conformational sampling could be conducive to tropoelastins interactions between cell-surface receptors and elastic fiber-associated proteins. Res. A., Torres, A. R., Alvarez, V. L., and Janata, J. Matrix Biol. eLife 6:e26526. Mater. J. Biochem. Biophys. 624, 137146. Natl. 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). 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. 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 hydrophobic domain 26 of human tropoelastin is unstructured in solution. Proc. Biopolymers 107:e23007. 38, 280291. Biochimie 86, 173178. Further to this, the flexibility of the hydrophobic domains may also play a key role in self-assembly. A. Communication: coacervation of tropoelastin results in fiber formation. 41, 494497. Copyright 2021 Ozsvar, Yang, Cain, Baldock, Tarakanova and Weiss. Biochim. 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). Genet. 276, 3603536042. 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. Adv. Fluorescently labelled mesenchymal stem cells growing on tropoelastin. Commun. J. Pathol. Proline-poor hydrophobic domains modulate the assembly and material properties of polymeric elastin. 13, 739743. J. Biol. A., Rongish, B. J., Czirok, A., Zach, J., Little, C. D., Davis, E. C., et al. Co-author Professor Anthony Weiss from the Charles Perkins Centre and Faculty of Science explained: "Tropoelastin can repair the heart because it is a precise replica of the body's natural elastic protein,". Sequence and structure determinants for the self-aggregation of recombinant polypeptides modeled after human elastin. doi: 10.1126/sciadv.1501145, Yeo, G. C., and Weiss, A. S. (2019). Sci. (2017). 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). (2008). 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. 98, 416. Elastic fibers are composed of approximately 90% elastin, whilst the remaining components are primarily comprised of fibrillin glycoproteins (Mecham, 1991). 220, 312324. doi: 10.1016/0014-4800(65)90015-8, He, D., Chung, M., Chan, E., Alleyne, T., Ha, K. C. H., Miao, M., et al. 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). Lyophilized Powder. Coacervation of recombinant human tropoelastin is strongly influenced by the concentration of protein and NaCl and to a lesser extent on pH. Biophys. Biol. Biopolymers 20, 12471260. doi: 10.1080/07391102.1992.10508661, Tamburro, A. M., Pepe, A., and Bochicchio, B. Elastin binding protein and FKBP65 modulate in vitro self-assembly of human tropoelastin. Acad. doi: 10.1074/jbc.M501390200, Chung, M. I., Miao, M., Stahl, R. J., Chan, E., Parkinson, J., and Keeley, F. W. (2006). doi: 10.1016/j.ajhg.2009.09.013. Coacervation is an endothermic, entropically favorable process through which tropoelastin monomers self-assemble into higher order n-mer structures. With leaps in the improvement of cryogenic electron microscopy to characterize flexible molecules, we predict that this approach will contribute to a deeper understanding of tropoelastin structure and self-assembly in the context of endogenous fiber formation and biomaterials fabrication. Alternative splicing of human elastin mRNA indicated by sequence analysis of cloned genomic and complementary DNA. Allergan plc (NYSE: AGN), headquartered in Dublin, Ireland, is a bold, global biopharmaceutical company. 10, 441454. Total synthesis and expression in Escherichia coli of a gene encoding human tropoelastin. Another region of note is domain 36, which contains lysines but does not participate in cross-linking (Hedtke et al., 2019). The Weiss Lab's research focuses on the use of human tropoelastin in tissue assembly and wound repair. Eng. Pathol. Marked longevity of human lung parenchymal elastic fibers deduced from prevalence of D-aspartate and nuclear weapons-related radiocarbon. 167, 94103. Figure 1. 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. 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). Elastin synthesis during perinatal lung development in the rat. Water structure and elastin-like peptide aggregation. Sci. doi: 10.1074/jbc.270.30.17778, Cain, S. A., Baldock, C., Gallagher, J., Morgan, A., Bax, D. V., Weiss, A. S., et al. Biochem. Ann. J. Biol. The human ELN gene is located on the long arm of chromosome 7q11.2 and comprises of 34 exons nestled between lengthy introns (Indik et al., 1987, 1989; Bashir et al., 1989). 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). 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. 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 . The first is an intracellular role as a tropoelastin chaperone and the second is as part of the elastin receptor complex (ERC). 281, 2375723765. Matrix Biol. Acta Histochem. . Pepe, A., Flamia, R., Guerra, D., Quaglino, D., Bochicchio, B., Pasquali Ronchetti, I., et al. Structural analysis of photocrosslinkable methacryloyl-modified protein derivatives. Stages of hierarchical assembly of elastic fibers. Cytochem. Bull. Biochemistry 45, 95189530. The authors wrote and submitted this manuscript in response to an invitation by the Editor. Vallet, S. D., Miele, A. E., Uciechowska-Kaczmarzyk, U., Liwo, A., Duclos, B., Samsonov, S. A., et al. The hydrophobic domains contain aliphatic amino acids with proline variations that provide flexibility and the ability to assemble into higher order structures. Chem. Hydrophobic domains of human tropoelastin interact in a context-dependent manner. 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). Cell Biol. Chem. doi: 10.1006/jmbi.1995.0502, Yeo, G. C., Baldock, C., Tuukkanen, A., Roessle, M., Dyksterhuis, L. B., Wise, S. G., et al. 69, 89102. Matrix 12, 156162. 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. Codistribution analysis of elastin and related fibrillar proteins in early vertebrate development. Anal. J. Biol. 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). Molecular modeling of protein materials: case study of elastin. Sci. doi: 10.1016/s0968-4328(99)00082-7, Tajima, S., Wachi, H., Uemura, Y., and Okamoto, K. (1997). Mater. Received: 17 December 2020; Accepted: 08 February 2021;Published: 25 February 2021. J. Struct. doi: 10.1074/jbc.M107920200, Tu, Y., and Weiss, A. S. (2010). February 14, 2018 Michael Patrini. doi: 10.1172/jci115204, Sherratt, M., Wess, T. J., Baldock, C., Ashworth, J., Purslow, P., Shuttleworth, C., et al. Matrix Biol. J. J. Biol. Biochemistry 37, 1461314622. Elastagens revolutionary technology is based on recombinant human tropoelastin, the precursor of elastin which is a key component of youthful skin. Res. Crosslinking [ edit] (1989). U.S.A. 116, 20422051. doi: 10.1002/bip.360291403, Luo, P., and Baldwin, R. L. (1997). Model. Bonnans, C., Chou, J., and Werb, Z. Proc. 252, 351365. Fibulin-4 and -5, but not fibulin-2, are associated with tropoelastin deposition in elastin-producing cell culture. Acta Biomater. Background: Elastin is an essential component of the dermis, providing skin with elasticity and integrity. (1977). Transglutaminase-mediated cross-linking of tropoelastin to fibrillin stabilises the elastin precursor prior to elastic fibre assembly. Elastagen is an exciting clinical-stage company with an advanced tissue repair platform based on tropoelastin. J. Med. Fibrillin-1 and -2 also interact with proteoglycans (Tiedemann et al., 2001), which coupled with tropoelastin/GAG interactions provide a pathway to the formation of elastic fibers. 120, 419426. (2015). (2021). 278, 4855348562. Synthesis and properties of crosslinked recombinant pro-resilin. Elastagen is creating injectables using recombinant human tropelastin, a substance that's crucial for producing elastin fibers in the skin. [Epub ahead of print]. Forty tropoelastin molecules were subjected to simulations using a MARTINI-based coarse-grained model, integrated with an elastic network model (Tarakanova et al., 2019a). Chem. doi: 10.1021/acs.biomac.8b01503, Rauscher, S., Baud, S., Miao, M., Keeley, F. W., and Poms, R. (2006). doi: 10.1016/0005-2795(73)90368-1, Franzblau, C., Faris, B., and Papaioannou, R. (1969). [Epub ahead of print]. Tropoelastins hydrophobic domains are primarily responsible for facilitating coacervation (Tamburro et al., 1992; Miao et al., 2003; Muiznieks et al., 2003).