Assembly of type I collagen: fusion of fibril subunits and the influence of fibril diameter on mechanical properties

Christiansen, David L.; Huang, Eric K.; Silver, Frederick H.

doi:10.1016/s0945-053x(00)00089-5

Cited by 265 publications

(188 citation statements)

References 36 publications

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“…However, many of the structural and functional features of assembled fibrils can be recreated in vitro under appropriate conditions using collagen extracted from a variety of source animal tissues into neutral salt or buffers, or, more frequently, into dilute acidic solutions (1). Fibrillogenesis can be controlled by varying the pH (17)(18)(19)(20), temperature (18,19,21,22), and buffer conditions (17,18,23,24). Under acidic conditions, collagen exists primarily as a soluble triple helix (17) below its melting transition around 42 C (24).…”

Section: Introductionmentioning

confidence: 99%

Circular Dichroism Spectroscopy of Collagen Fibrillogenesis: A New Use for an Old Technique

Drzewiecki

Grisham

Parmar

et al. 2016

Biophysical Journal

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Type-I collagen assembles in a stepwise, hierarchic fashion from the folding of the triple helix to the assembly of fibrils into fibers. The mature assembled fibers are crucial for tissue structure and mechanics, cell interactions, and other functions in vivo. Although triple helix folding can be followed with the use of optical methods such as circular dichroism (CD) spectroscopy, fibrillogenesis is typically measured by alternative methods such as turbidity, rheology, and microscopy. Together, these approaches allow for investigation of the mechanical properties and architectures of collagen-based scaffolds and excised tissues. Herein, we demonstrate that CD spectroscopy, a technique that is used primarily to evaluate the secondary structure of proteins, can also be employed to monitor collagen fibrillogenesis. Type-I collagen suspensions demonstrated a strong, negative ellipticity band between 204 and 210 nm under conditions consistent with fibrillogenesis. Deconvolution of CD spectra before, during, and after fibrillogenesis identified a unique fibril spectrum distinct from triple helix and random coil conformations. The ability to monitor multiple states of collagen simultaneously in one experiment using one modality provides a powerful platform for studying this complex assembly process and the effects of other factors, such as collagenases, on fibrillogenesis and degradation.

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Section: Introductionmentioning

confidence: 99%

Circular Dichroism Spectroscopy of Collagen Fibrillogenesis: A New Use for an Old Technique

Drzewiecki

Grisham

Parmar

et al. 2016

Biophysical Journal

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“…The thickness of that shell matches the thickness of the shell surrounding adjoining fibrils, producing a very precise centerto-center spacing between the collagen fibrils characteristic of the corneal stroma and necessary for its transparency (28). Through this interaction with collagen (mostly with type I), PGs play important biological roles in collagen fibrillogenesis and matrix assembly (29). They also may serve as binders of other proteins, some of which may be neurorepellants and neuroattractants (30).…”

mentioning

confidence: 99%

Effects of Ultraviolet-A and Riboflavin on the Interaction of Collagen and Proteoglycans during Corneal Cross-linking

Zhang

Conrad

2011

Journal of Biological Chemistry

161

112

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Corneal cross-linking using riboflavin and ultraviolet-A (RFUVA) is a clinical treatment targeting the stroma in progressive keratoconus. The stroma contains keratocan, lumican, mimecan, and decorin, core proteins of major proteoglycans (PGs) that bind collagen fibrils, playing important roles in stromal transparency. Here, a model reaction system using purified, non-glycosylated PG core proteins in solution in vitro has been compared with reactions inside an intact cornea, ex vivo, revealing effects of RFUVA on interactions between PGs and collagen cross-linking. Irradiation with UVA and riboflavin cross-links collagen ␣ and ␤ chains into larger polymers. In addition, RFUVA cross-links PG core proteins, forming higher molecular weight polymers. When collagen type I is mixed with individual purified, non-glycosylated PG core proteins in solution in vitro and subjected to RFUVA, both keratocan and lumican strongly inhibit collagen cross-linking. However, mimecan and decorin do not inhibit but instead form cross-links with collagen, forming new high molecular weight polymers. In contrast, corneal glycosaminoglycans, keratan sulfate and chondroitin sulfate, in isolation from their core proteins, are not cross-linked by RFUVA and do not form cross-links with collagen. Significantly, when RFUVA is conducted on intact corneas ex vivo, both keratocan and lumican, in their natively glycosylated form, do form cross-links with collagen. Thus, RFUVA causes cross-linking of collagen molecules among themselves and PG core proteins among themselves, together with limited linkages between collagen and keratocan, lumican, mimecan, and decorin. RFUVA as a diagnostic tool reveals that keratocan and lumican core proteins interact with collagen very differently than do mimecan and decorin.The cornea is the transparent, dome-shaped tissue covering the front of the eye. It is a powerful refracting surface, providing 65-75% of the eye's focusing power, and is made up of three distinct layers: epithelium, stroma, and endothelium. The stroma comprises about 90% of cornea thickness in humans (1).Although it is very highly innervated, it does not contain any blood vessels (2-4). Collagen gives the cornea its strength, elasticity, and form (5). The unique molecular shape, paracrystalline arrangement, and very regular fine diameter of the evenly spaced collagen fibrils are essential in producing a transparent cornea (6, 7).In the corneal stromal extracellular matrix, glycosaminoglycan (GAG) 2 polysaccharides are the most abundant negatively charged macromolecules and are classified on the basis of their repeating disaccharide structures into four main groups: keratan sulfate (KS), chondroitin sulfate/dermatan sulfate (CS/DS), heparan sulfate and heparin, and hyaluronan. Glycosaminoglycans, normally covalently attached to proteoglycan (PG) core proteins, play important roles in corneal transparency, nerve growth cone guidance, and cell adhesion, largely dependent on their patterns of sulfation or lack of it (8, 9). The corneal stroma is comp...

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“…2B) after 48 h of cultivation. Collagen gelation is influenced by many factors, like source and extraction method, concentration, pH value, ionic strength, temperature and CO 2 concentration during polymerization (Wood & Keech, 1960;Christiansen et al, 2000). Further, mechanical agitation during the nucleation phase can affect polymerization (Yang et al, 2009(Yang et al, , 2010.…”

Section: D Substrate Stretchermentioning

confidence: 99%

Quantification of substrate and cellular strains in stretchable 3D cell cultures: an experimental and computational framework

Gonzalez-Avalos

Mürnseer

Deeg

et al. 2017

Journal of Microscopy

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SummaryThe mechanical cell environment is a key regulator of biological processes . In living tissues, cells are embedded into the 3D extracellular matrix and permanently exposed to mechanical forces. Quantification of the cellular strain state in a 3D matrix is therefore the first step towards understanding how physical cues determine single cell and multicellular behaviour. The majority of cell assays are, however, based on 2D cell cultures that lack many essential features of the in vivo cellular environment. Furthermore, nondestructive measurement of substrate and cellular mechanics requires appropriate computational tools for microscopic image analysis and interpretation. Here, we present an experimental and computational framework for generation and quantification of the cellular strain state in 3D cell cultures using a combination of 3D substrate stretcher, multichannel microscopic imaging and computational image analysis. The 3D substrate stretcher enables deformation of living cells embedded in bead-labelled 3D collagen hydrogels. Local substrate and cell deformations are determined by tracking displacement of fluorescent beads with subsequent finite element interpolation of cell strains over a tetrahedral tessellation. In this feasibility study, we debate diverse aspects of deformable 3D culture construction, ¶ These two authors contribute equally.

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Assembly of type I collagen: fusion of fibril subunits and the influence of fibril diameter on mechanical properties

Cited by 265 publications

References 36 publications

Circular Dichroism Spectroscopy of Collagen Fibrillogenesis: A New Use for an Old Technique

Circular Dichroism Spectroscopy of Collagen Fibrillogenesis: A New Use for an Old Technique

Effects of Ultraviolet-A and Riboflavin on the Interaction of Collagen and Proteoglycans during Corneal Cross-linking

Quantification of substrate and cellular strains in stretchable 3D cell cultures: an experimental and computational framework

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