scholarly journals Lumican Regulates Collagen Fibril Assembly: Skin Fragility and Corneal Opacity in the Absence of Lumican

1998 ◽  
Vol 141 (5) ◽  
pp. 1277-1286 ◽  
Author(s):  
Shukti Chakravarti ◽  
Terry Magnuson ◽  
Jonathan H. Lass ◽  
Karl J. Jepsen ◽  
Christian LaMantia ◽  
...  
Keyword(s):  
Collagen Fibril ◽  
Significant Proportion ◽  
Keratan Sulfate ◽  
Corneal Opacity ◽  
Collagen Fibrils ◽  
Mutant Mice ◽  
Connective Tissues ◽  
Ehlers Danlos Syndrome ◽  
Transmission Electron ◽  
Skin Fragility

Lumican, a prototypic leucine-rich proteoglycan with keratan sulfate side chains, is a major component of the cornea, dermal, and muscle connective tissues. Mice homozygous for a null mutation in lumican display skin laxity and fragility resembling certain types of Ehlers-Danlos syndrome. In addition, the mutant mice develop bilateral corneal opacification. The underlying connective tissue defect in the homozygous mutants is deregulated growth of collagen fibrils with a significant proportion of abnormally thick collagen fibrils in the skin and cornea as indicated by transmission electron microscopy. A highly organized and regularly spaced collagen fibril matrix typical of the normal cornea is also missing in these mutant mice. This study establishes a crucial role for lumican in the regulation of collagen assembly into fibrils in various connective tissues. Most importantly, these results provide a definitive link between a necessity for lumican in the development of a highly organized collagenous matrix and corneal transparency.

Growth and development of collagen fibrils in immature tissues from rat and sheep

1981 ◽  
Vol 212 (1186) ◽  
pp. 85-92 ◽  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Collagen Fibril ◽  
Growth And Development ◽  
Collagen Fibrils ◽  
Diameter Distribution ◽  
Rat Tissues ◽  
Transmission Electron ◽  
The Mean ◽  
Fibril Diameter

The collagen fibril diameter distribution of four immature tissues from both rat and sheep have been determined from transverse sections observed in the transmission electron microscope. In many instances before birth, the form of the distribution for the tissues is both unimodal and sharp and the mean diameters of the distributions lie close to a multiple of 80 Å. For some tissues, the collagen fibril diameter distributions may be resolved into a number of components, each of which represents a population of fibrils with a diameter close to a multiple of 80 Å (8 nm). These data confirm and extend previous observations by the authors that small collagen fibrils all have diameters that are multiples of about 80 Å and that the fibril growth occurs by the accretion of 80 Å units. The form of the collagen fibril diameter distribution at birth is broad for the sheep tissues but narrow for the rat tissues, thus confirming that the range of fibril diameters at this stage of life reflects the differing degree of development of precocious and altricious animals.

scholarly journals A Critical Role for the Membrane-type 1 Matrix Metalloproteinase in Collagen Phagocytosis

2006 ◽  
Vol 17 (11) ◽  
pp. 4812-4826 ◽  
Author(s):  
Hyejin Lee ◽  
Christopher M. Overall ◽  
Christopher A. McCulloch ◽  
Jaro Sodek
Keyword(s):  
Inflammatory Diseases ◽  
Human Fibroblasts ◽  
Critical Role ◽  
Collagen Fibrils ◽  
Connective Tissues ◽  
Transmission Electron ◽  
Catalytically Active ◽  
Membrane Type ◽  
Collagen Phagocytosis ◽  
Interfering Rna

Degradation of collagen is important for the physiological remodeling of connective tissues during growth and development as well as in wound healing, inflammatory diseases, and cancer cell invasion. In remodeling adult tissues, degradation of collagen occurs primarily through a phagocytic pathway. However, although various steps in the phagocytic pathway have been characterized, the enzyme required to initially fragment collagen fibrils for subsequent phagocytosis has not been identified. We have used laser confocal microscopy, transmission electron microscopy, and biochemical assays to show that human fibroblasts initiate degradation of collagen through the collagenase activity of the membrane-bound metalloproteinase MT1-MMP. Degradation of natural and reconstituted collagen substrates correlated with the expression of MT1-MMP, which was localized at sites of collagen cleavage at the surface of the cells and also within the cells, whereas collagen degradation was abrogated when MT1-MMP expression was blocked by small interfering RNA treatment. In contrast to MT1-MMP, the gelatinolytic activity of MMP-2 was not required for collagen phagocytosis. These studies demonstrate a pivotal role of catalytically active MT1-MMP in preparing collagen fibrils for phagocytic degradation.

Phagocytosis of collagen by fibroblasts and invasive cancer cells is mediated by MT1-MMP

2007 ◽  
Vol 35 (4) ◽  
pp. 704-706 ◽  
Author(s):  
H. Lee ◽  
K.L. Sodek ◽  
Q. Hwang ◽  
T.J. Brown ◽  
M. Ringuette ◽  
...  
Keyword(s):  
Inflammatory Diseases ◽  
Collagen Fibrils ◽  
Connective Tissues ◽  
Cancer Breast ◽  
Metastatic Cells ◽  
Transmission Electron ◽  
Biochemical Assays ◽  
Catalytically Active ◽  
Membrane Type ◽  
Collagen Phagocytosis

Degradation of collagen is required for the physiological remodelling of connective tissues during growth and development, as well as in wound healing, inflammatory diseases, and cancer cell invasion. In remodelling adult tissues, degradation of collagen occurs primarily through a phagocytic pathway. While various steps in this pathway have been characterized, the enzyme required to fragment collagen fibrils for phagocytosis has not been identified. Laser confocal microscopy, transmission electron microscopy and biochemical assays were used to show that degradation of collagen substrates by fibroblasts correlated with the expression of the membrane-bound metalloproteinase MT1-MMP (membrane-type 1 matrix metalloproteinase). The MT1-MMP was localized to sites of collagen cleavage on the cell surface and also within the cells. In contrast with MT1-MMP, the gelatinase MMP-2 was not required for collagen phagocytosis. Similar analyses of several ovarian cancer, breast cancer and fibrosarcoma cells indicated that highly metastatic cells also degrade collagen through a phagocytic pathway that is mediated by MT1-MMP. Collectively, these studies demonstrate a pivotal role for catalytically active MT1-MMP in preparing collagen fibrils for phagocytic degradation by normal and transformed cells.

scholarly journals Collagen Fibril Ultrastructure in Mice Lacking Discoidin Domain Receptor 1

2016 ◽  
Vol 22 (3) ◽  
pp. 599-611 ◽  
Author(s):  
Jeffrey R. Tonniges ◽  
Benjamin Albert ◽  
Edward P. Calomeni ◽  
Shuvro Roy ◽  
Joan Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Collagen Fibril ◽  
Collagen Fibrils ◽  
Collagen Deposition ◽  
Knock Out ◽  
Discoidin Domain Receptor ◽  
Transmission Electron ◽  
Fibril Diameter ◽  
Discoidin Domain Receptor 1

AbstractThe quantity and quality of collagen fibrils in the extracellular matrix (ECM) have a pivotal role in dictating biological processes. Several collagen-binding proteins (CBPs) are known to modulate collagen deposition and fibril diameter. However, limited studies exist on alterations in the fibril ultrastructure by CBPs. In this study, we elucidate how the collagen receptor, discoidin domain receptor 1 (DDR1) regulates the collagen content and ultrastructure in the adventitia of DDR1 knock-out (KO) mice. DDR1 KO mice exhibit increased collagen deposition as observed using Masson’s trichrome. Collagen ultrastructure was evaluated in situ using transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. Although the mean fibril diameter was not significantly different, DDR1 KO mice had a higher percentage of fibrils with larger diameter compared with their wild-type littermates. No significant differences were observed in the length of D-periods. In addition, collagen fibrils from DDR1 KO mice exhibited a small, but statistically significant, increase in the depth of the fibril D-periods. Consistent with these observations, a reduction in the depth of D-periods was observed in collagen fibrils reconstituted with recombinant DDR1-Fc. Our results elucidate how DDR1 modulates collagen fibril ultrastructure in vivo, which may have important consequences in the functional role(s) of the underlying ECM.

Systematic investigation of the skin in Chst14−/− mice: A model for skin fragility in musculocontractural Ehlers–Danlos syndrome caused by CHST14 variants (mcEDS-CHST14)

Glycobiology ◽  
2020 ◽  
Author(s):  
Takuya Hirose ◽  
Shuji Mizumoto ◽  
Ayana Hashimoto ◽  
Yuki Takahashi ◽  
Takahiro Yoshizawa ◽  
...  
Keyword(s):  
Chondroitin Sulfate ◽  
Anion Exchange ◽  
Dermatan Sulfate ◽  
Systematic Investigation ◽  
Exchange Chromatography ◽  
Collagen Fibrils ◽  
Loss Of Function ◽  
Ehlers Danlos Syndrome ◽  
Skin Fragility ◽  
Danlos Syndrome

Abstract Loss-of-function variants in CHST14 cause a dermatan 4-O-sulfotransferase deficiency named musculocontractural Ehlers–Danlos syndrome-CHST14 (mcEDS-CHST14), resulting in complete depletion of the dermatan sulfate moiety of decorin glycosaminoglycan (GAG) chains, which is replaced by chondroitin sulfate. Recently, we uncovered structural alteration of GAG chains in the skin of patients with mcEDS-CHST14. Here, we conducted the first systematic investigation of Chst14 gene-deleted homozygote (Chst14−/−) mice. We used skin samples of wild-type (Chst14+/+) and Chst14−/− mice. Mechanical fragility of the skin was measured with a tensile test. Pathology was observed using light microscopy, decorin immunohistochemistry and electron microscopy (EM) including cupromeronic blue (CB) staining. Quantification of chondroitin sulfate and dermatan sulfate was performed using enzymatic digestion followed by anion-exchange HPLC. In Chst14−/− mice, skin tensile strength was significantly decreased compared with that in Chst14+/+ mice. EM showed that collagen fibrils were oriented in various directions to form disorganized collagen fibers in the reticular layer. Through EM-based CB staining, rod-shaped linear GAG chains were found to be attached at one end to collagen fibrils and protruded outside of the fibrils, in contrast to them being round and wrapping the collagen fibrils in Chst14+/+ mice. A very low level of dermatan sulfate disaccharides was detected in the skin of Chst14−/− mice by anion-exchange chromatography. Chst14−/− mice, exhibiting similar abnormalities in the GAG structure of decorin and collagen networks in the skin, could be a reasonable model for skin fragility of patients with mcEDS-CHST14, shedding light on the role of dermatan sulfate in maintaining skin strength.

A comparison of the size distribution of collagen fibrils in connective tissues as a function of age and a possible relation between fibril size distribution and mechanical properties

1978 ◽  
Vol 203 (1152) ◽  
pp. 305-321 ◽  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Size Distribution ◽  
Collagen Fibril ◽  
Average Diameter ◽  
Collagen Fibrils ◽  
Diameter Distribution ◽  
Connective Tissues ◽  
Fibril Diameter ◽  
Covalent Crosslinks

Data on the distribution of collagen fibril diameters in various connective tissues have been collected and analysed for common features. The diameter distributions of the collagen fibrils at birth and in the foetal stages of development are unimodal, whereas at maturity the mass-average diameter of the collagen fibrils is generally larger than at birth and the distributions of fibril sizes may be either unimodal or bimodal depending on the tissue. At senescence, few data are available but in most instances both the mean and mass-average diameters of the collagen fibrils are smaller than those at maturity and the fibril distributions are mainly bimodal. The division between tissues showing unimodal or bimodal fibril distributions at maturity does not simply relate to the type I collagen/type II collagen classification, to the distinction between orientated and unorientated material or indeed directly to the levels of stress and strain encountered by the tissue. However, there may prove to be a relation between a bimodal fibril diameter distribution at maturity and the maintenance over long periods of time of either high stress in stretched tissues or low stress in compressed tissues. It has also been noted that the width of the collagen fibril diameter distribution at birth differs between altricious and precocious animals. The ultimate tensile strength of a connective tissue and the mass-average diameter of the constituent collagen fibrils have been shown to have a positive correlation. Further, the form of the collagen fibril diameter distribution can be directly related to the mechanical properties of the tissue. In particular, it is postulated that the size distribution of the collagen fibrils is largely determined by two factors. First, if the tissue is primarily designed to have high tensile strength, then an increase in the diameter of the collagen fibrils will parallel an increase in the potential density of intrafibrillar covalent crosslinks. Consequently large collagen fibrils are predicted to have a greater tensile strength than small fibrils. Secondly, if the tissue is designed to be elastic and hence withstand creep, then a reduction in the diameter of the collagen fibrils will effectively increase the surface area per unit mass of the fibrils thus enhancing the probability of interfibrillar non-covalent crosslinks between the collagen fibrils and the components of the matrix. The idealized description given may indicate how the mechanical properties of a tissue may be interpreted in terms of the collagen fibril diameter distribution.

Banded Structures in the Connective Tissue of Meningioma

1976 ◽  
Vol 34 ◽  
pp. 234-235
Author(s):  
C. N. Sun ◽  
H. J. White
Keyword(s):  
Connective Tissue ◽  
Osmium Tetroxide ◽  
Uranyl Acetate ◽  
Collagen Fibrils ◽  
Lead Citrate ◽  
Connective Tissues ◽  
Native Collagen ◽  
Routine Procedures

Previously, we have reported on extracellular cross-striated banded structures in human connective tissues of a variety of organs (1). Since then, more material has been examined and other techniques applied. Recently, we studied a fibrocytic meningioma of the falx. After the specimen was fixed in 4% buffered glutaraldehyde and post-fixed in 1% buffered osmium tetroxide, other routine procedures were followed for embedding in Epon 812. Sections were stained with uranyl acetate and lead citrate. There were numerous cross striated banded structures in aggregated bundle forms found in the connecfive tissue of the tumor. The banded material has a periodicity of about 450 Å and where it assumes a filamentous arrangement, appears to be about 800 Å in diameter. In comparison with the vicinal native collagen fibrils, the banded material Is sometimes about twice the diameter of native collagen.

scholarly journals Hydrothermal Synthesis of Iridium-Substituted NaTaO3 Perovskites

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1537
Author(s):  
David L. Burnett ◽  
Christopher D. Vincent ◽  
Jasmine A. Clayton ◽  
Reza J. Kashtiban ◽  
Richard I. Walton
Keyword(s):  
Significant Proportion ◽  
Edge Length ◽  
Perovskite Oxide ◽  
Hydrogen Yield ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Profile Fitting ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
One Step

Iridium-containing NaTaO3 is produced using a one-step hydrothermal crystallisation from Ta2O5 and IrCl3 in an aqueous solution of 10 M NaOH in 40 vol% H2O2 heated at 240 °C. Although a nominal replacement of 50% of Ta by Ir was attempted, the amount of Ir included in the perovskite oxide was only up to 15 mol%. The materials are formed as crystalline powders comprising cube-shaped crystallites around 100 nm in edge length, as seen by scanning transmission electron microscopy. Energy dispersive X-ray mapping shows an even dispersion of Ir through the crystallites. Profile fitting of powder X-ray diffraction (XRD) shows expanded unit cell volumes (orthorhombic space group Pbnm) compared to the parent NaTaO3, while XANES spectroscopy at the Ir LIII-edge reveals that the highest Ir-content materials contain Ir4+. The inclusion of Ir4+ into the perovskite by replacement of Ta5+ implies the presence of charge-balancing defects and upon heat treatment the iridium is extruded from the perovskite at around 600 C in air, with the presence of metallic iridium seen by in situ powder XRD. The highest Ir-content material was loaded with Pt and examined for photocatalytic evolution of H2 from aqueous methanol. Compared to the parent NaTaO3, the Ir-substituted material shows a more than ten-fold enhancement of hydrogen yield with a significant proportion ascribed to visible light absorption.

Ultrastructure of commercial recycled pulp fibers for the production of packaging paper

Holzforschung ◽  
2005 ◽  
Vol 59 (6) ◽  
pp. 675-680 ◽  
Author(s):  
Jonas Brändström ◽  
Jean-Paul Joseleau ◽  
Alain Cochaux ◽  
Nathalie Giraud-Telme ◽  
Katia Ruel
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Significant Proportion ◽  
Pulp Fibers ◽  
Chemical Pulp ◽  
Recycled Pulp ◽  
Transmission Electron ◽  
Large Heterogeneity ◽  
Recycled Fibers ◽  
Packaging Paper

Abstract Transmission electron microscopy was used to investigate the ultrastructure of recycled pulp fibers originating from a household collection plant and intended for the production of packaging paper. Three recovered paper grades and recycling processes, including pulping, screening, cleaning and refining, were assessed with emphasis on surface and internal fibrillation as well as xylan localization. Results showed a large heterogeneity with respect to fiber ultrastructure within and between the grades. Screening and cleaning steps had no detectable effects, but refining clearly increased cell-wall delamination and surface fibrillation. Immunolabeling of xylans showed that they were distributed rather evenly across the cell walls. They were also present on fines. Two different mechanisms for fiber delamination and surface fibrillation were found, one which implies that internal and external fibrillation take place simultaneously across the cell wall, and another which implies successive peeling of layers or sub-layers from the outside towards the inside. It is suggested that recycled fibers of chemical pulp origin undergo the former mechanism and recycled fibers that contain lignin binding the cell wall matrix give rise to the latter peeling mechanism. Because several recycled fibers were severely delaminated and almost fractured, we suggest that to produce a good packaging paper, it is important that recycled pulp should contain a significant proportion of fibers with high intrinsic strength.

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