Targeted Modulation of Tropoelastin Structure and Assembly

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.

3D Bioprinting in Skeletal Muscle Tissue Engineering

“…They observed higher sarcomeric organization and differentiation at day 7 of culture on collagen coated aligned fibers and aligned fiber scaffolds compared to random fiber scaffolds. [105,106] In another example of biomimetic muscle bundle fabrication, Kim and colleagues fabricated a microfibrous PCL bundle by using a melt-printing system to print at 85 °C a PVA/PCL (ratio 3:7) solution with a 350 µm nozzle at a speed of 10 mm s −1 and a pneumatic pressure of 250 kPa. The sacrificial PVA was removed in water after 24 h, then the PCL structure was coated with 0.5% collagen crosslinked by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) for 30 min, and the scaffold was freeze dried for 12 h. Due to the microfibrillation of PVA and the leaching of PVA from the mixture of PVA/PC, the scaffold had a surface with aligned microfibrous pattern and a section allowing cell penetration between the microfibers (Figure 6a).…”

Elastin‐Like Recombinamers: Deconstructing and Recapitulating the Functionality of Extracellular Matrix Proteins Using Recombinant Protein Polymers

“…[76,85] Indeed, local mutations in the sequence result in global modifications that may disrupt the shape of the molecule and potentially alter the exposure of the bioactive motifs and the final functional assembly into the elastic fiber. [86][87][88] The N-terminal coil region provides elastic properties to tropoelastin in its uncrosslinked state and is associated with the regulation of self-assembly and crosslinking during elastogenesis. [84] The hinge and bridge regions are highly flexible and contribute to elastic fiber assembly and mechanical coupling.…”

“…[ 76,85 ] Indeed, local mutations in the sequence result in global modifications that may disrupt the shape of the molecule and potentially alter the exposure of the bioactive motifs and the final functional assembly into the elastic fiber. [ 86–88 ]…”

Unique molecular networks: Formation and role of elastin cross‐links

“…It has been shown that the insertion or deletion of TE domains or the mutation of certain amino acid residues affects diverse mechanisms associated with the assembly of TE monomers into a polymeric network such as coacervation and cross‐linking processes as well as the resultant mechanical properties. This suggests that variations in the TE sequence allow tissue‐specific alterations in elastin properties or are responsible for abnormal fiber formation under pathological conditions …”

“…This suggests that variations in the TE sequence allow tissue-specific alterations in elastin properties or are responsible for abnormal fiber formation under pathological conditions. [15][16][17] TE's sequence is highly repetitive and about 80% are composed of the four amino acids Gly, Ala, Val, and Pro. The precursor has alternating hydrophobic and more hydrophilic domains, which are encoded by individual exons, so that the domain structure of the protein is reflected in the exon organization of its gene.…”