Tropoelastin interacts with cell-surface glycosaminoglycans via its COOH-terminal domain.
ABSTRACT Using a biochemical and cell biological approach, we have identified a cell interaction site at the carboxyl terminus of tropoelastin. Cell interactions with the COOH-terminal sequence are not through the elastin-binding protein (EBP67) because neither VGVAPG-like peptides nor galactoside sugars altered adhesion. Our results also show that cell adhesion to tropoelastin is not promoted by integrins. Through the use of mutant Chinese hamster ovary cell lines defective in glycosaminoglycan biosynthesis, as well as competition studies and enzymatic removal of specific cell-surface glycosaminoglycans, the tropoelastin-binding moieties on the cell surface were identified as heparan and chondroitin sulfate-containing glycosaminoglycans, with heparan sulfate being greatly preferred. Heparin affinity chromatography combined with cell adhesion assays identified the last 17 amino acids as the sequence element at the carboxyl terminus of tropoelastin responsible for the adhesive activity.
- SourceAvailable from: Lisa Muiznieks[Show abstract] [Hide abstract]
ABSTRACT: Elastin self-assembles from monomers into polymer networks that display elasticity and resilience. The first major step in assembly is a liquid-liquid phase separation known as coacervation. This process represents a continuum of stages from initial phase separation to early growth of droplets by coalescence and later "maturation" leading to fibre formation. Assembly of tropoelastin-rich globules is on pathway for fibre formation in vivo. However, little is known about these intermediates beyond their size distribution. Here we investigate the contribution of sequence and structural motifs from full-length tropoelastin and a set of elastin-like polypeptides to the maturation of coacervate assemblies, observing their growth, stability and interaction behaviour, and polypeptide alignment within matured globules. We conclude that maturation is driven by surface properties, leading to stabilization of the interface between the hydrophobic interior and aqueous solvent, potentially through structural motifs, and discuss implications for droplet interactions in fibre formation.Matrix biology: journal of the International Society for Matrix Biology 04/2014; · 3.56 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Proteins display an essential role in numerous natural systems due to their structural and biological properties. Given their unique properties, proteins have been thoroughly investigated in the last few decades, offering a myriad of solutions for the development of innovative biomaterials, including films, foams, composites and gels, in particular for biomedical applications such as drug delivery systems, biosensors and scaffolds for tissue regeneration. In this context, this review intends to give a general overview of the potential of protein based materials within the sustainable polymers context, covering aspects ranging from protein types, selection/isolation to properties of protein based (nano)materials and biomedical applications, passing through preparation methodologies of materials.Journal of Materials Chemistry B. 03/2014; 2:3715-3740.
- [Show abstract] [Hide abstract]
ABSTRACT: Tropoelastin is an extracellular matrix protein that assembles into elastic fibers which provide elasticity and strength to vertebrate tissues. While 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. On the other hand, 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 cross-links aberrantly into denser, less porous hydrogels with reduced swelling properties. While 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 D72 site in stabilizing the N-terminal segment of human tropoelastin, and the importance of this region in facilitating elastic fiber assembly.Journal of Biological Chemistry 10/2014; · 4.60 Impact Factor