Extracellular matrix 4: The elastic fiber

Abstract

The elastic properties of many tissues such as the lung, dermis, and large blood vessels are due to the presence of elastic fibers in the extracellular space. These fibers have been shown by biochemical and ultrastructural analysis to be composed of two distinct components, a more abundant amorphous component and a 10-12 nm microfibrillar component, which is located primarily around the periphery of the amorphous component. The protein elastin makes up the highly insoluble amorphous component and is responsible for the elastic properties. Elastin is found throughout the vertebrate kingdom and possesses an unusual chemical composition rich in glycine, proline, and hydrophobic amino acids, consonant with its characteristic physical properties. The 72-kDa biosynthetic precursor, tropoelastin, is secreted into the extracellular space where it becomes highly cross-linked into a rubber-like network through the activity of the copper-requiring enzyme lysyl oxidase. Analysis of the elastin gene has demonstrated that hydrophobic and cross-linking domains are encoded in separate exons and that there is significant alternative splicing, resulting in multiple isoforms of tropoelastin. The elastin gene promoter contains many potential binding sites for various modulating factors indicative of a complex pattern of transcriptional regulation. The microfibrils contain several proteins, including fibrillin, and probably act as an organizing scaffold in the formation of the elastin network. There appears to be a fibrillin gene family in which each protein contains multiple repeats of a motif previously found in epidermal growth factor and a second motif observed in transforming growth factor beta 1-binding protein. Mutations in the fibrillin gene located on human chromosome 15 have been strongly implicated as the cause of the Marfan syndrome.

Cell adhesion and integrin binding to recombinant human fibrillin‐1

“…In addition, the assembly of microfibrils and elastic fibers might depend on fibrillin interactions with cells. Elastic fiber assembly typically occurs at infoldings of the cell surface, where microfibrils are seen close to the cell membrane [30]. Specific binding of integrin c~VI33 to fibrillin-1 may also play an important role during angiogenesis.…”

Distribution of the elastic fiber and associated proteins in flexor tendon reflects function

“…The elastic fiber plays an important mechanical role in extensible tissues such as muscular blood vessels, lung, and skin (for reviews, see Rosenbloom et al, 1993;Dietz and Mecham, 2000;Starcher, 2000). The proteins elastin, fibrillin 1 and 2, and microfibril-associated glycoproteins (MAGPs) 1 and 2 are known to be components of the elastic fiber.…”

“…MAGP-1 and MAGP-2 have been immunolocalized to fibrillin-containing microfibrils; however, the function of these two proteins is entirely unknown. Fibrillin-containing microfibrils are thought to serve as a framework for the deposition of elastin and thus forming the elastic fiber superstructure (Rosenbloom et al, 1993;Kielty and Shuttleworth, 1995). Fibrillin-containing fibers are also found without elastin in some tissues (Gibson and Cleary, 1987;Wright et al, 1994;Zhang et al, 1995).…”

Elastin Based Constructs

“…The Young's modulus for elastic fibers typically ranges from 300 -600 kPa although it can measure as low as 100 kPa for arterial elastin, highlighting the versatile nature of these structures within the ECM (Mithieux and Weiss 2005;Zou and Zhang 2009). Although the mechanism for elasticity has not been fully elucidated, elastic recoil likely to be entropically driven whereby extension of the protein results in a more ordered structure and thus recoil occurs so the protein can return to a disorder state (reviewed by (Rosenbloom, Abrams et al 1993;Vrhovski and Weiss 1998). This elasticity is due to the inherent elastic properties of the monomer (Holst, Watson et al 2010;Baldock, Oberhauser et al 2011).…”