Collagen cross-linking mediated by lysyl hydroxylase 2: an enzymatic battlefield to combat fibrosis

2019 ◽  
Vol 63 (3) ◽  
pp. 377-387 ◽  
Author(s):  
Bram Piersma ◽  
Ruud A. Bank

Abstract The hallmark of fibrosis is an excessive accumulation of collagen, ultimately leading to organ failure. It has become evident that the deposited collagen also exhibits qualitative modifications. A marked modification is the increased cross-linking, leading to a stabilization of the collagen network and limiting fibrosis reversibility. Not only the level of cross-linking is increased, but also the composition of cross-linking is altered: an increase is seen in hydroxyallysine-derived cross-links at the expense of allysine cross-links. This results in irreversible fibrosis, as collagen cross-linked by hydroxyallysine is more difficult to degrade. Hydroxyallysine is derived from a hydroxylysine in the telopeptides of collagen. The expression of lysyl hydroxylase (LH) 2 (LH2), the enzyme responsible for the formation of telopeptidyl hydroxylysine, is universally up-regulated in fibrosis. It is expected that inhibition of this enzyme will lead to reversible fibrosis without interfering with the normal repair process. In this review, we discuss the molecular basis of collagen modifications and cross-linking, with an emphasis on LH2-mediated hydroxyallysine cross-links, and their implications for the pathogenesis and treatment of fibrosis.

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Marwa Kamel ◽  
Mohamed Wagih ◽  
Gokhan S. Kilic ◽  
Concepcion R. Diaz-Arrastia ◽  
Mohamed A. Baraka ◽  
...  

The role of the extracellular matrix (ECM) in uterine fibroids (UF) has recently been appreciated. Overhydroxylation of lysine residues and the subsequent formation of hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) cross-links underlie the ECM stiffness and profoundly affect tumor progression. The aim of the current study was to investigate the relationship between ECM of UF, collagen and collagen cross-linking enzymes [lysyl hydroxylases (LH) and lysyl oxidases (LOX)], and the development and progression of UF. Our results indicated that hydroxyl lysine (Hyl) and HP cross-links are significantly higher in UF compared to the normal myometrial tissues accompanied by increased expression of LH (LH2b) and LOX. Also, increased resistance to matrix metalloproteinases (MMP) proteolytic degradation activity was observed. Furthermore, the extent of collagen cross-links was positively correlated with the expression of myofibroblast marker (α-SMA), growth-promoting markers (PCNA; pERK1/2;FAKpY397; Ki-67; and Cyclin D1), and the size of UF. In conclusion, our study defines the role of overhydroxylation of collagen and collagen cross-linking enzymes in modulating UF cell proliferation, differentiation, and resistance to MMP. These effects can establish microenvironment conducive for UF progression and thus represent potential target treatment options of UF.


1997 ◽  
Vol 322 (2) ◽  
pp. 535-542 ◽  
Author(s):  
Lynda KNOTT ◽  
John F. TARLTON ◽  
Allen J. BAILEY

With age, the proximal sections of turkey leg tendons become calcified, and this phenomenon has led to their use as a model for collagen mineralization. Mineralizing turkey leg tendon was used in this study to characterize further the composition and cross-linking of collagen in calcified tissues. The cross-link profiles of mineralizing collagen are significantly different from those of other collagenous matrices with characteristically low amounts of hydroxylysyl-pyridinoline and the presence of lysyl-pyridinoline and pyrrolic cross-links. However, the presence of the immature cross-link precursors previously reported in calcifying tissues was not supported in the present study, and was found to be due to the decalcification procedure using EDTA. Analysis of tendons from young birds demonstrated differences in the cross-link profile which indicated a higher level of hydroxylation of specific triple-helical lysines involved in cross-linking of the proximal tendon. This may be related to later calcification, suggesting that this part of the tendon is predestined to be calcified. The minimal changes in lysyl hydroxylation in both regions of the tendon with age were in contrast with the large changes in the cross-link profile, indicating differential hydroxylation of the helical and telopeptide lysine residues. Changes with age in the collagen matrix, its turnover and thermal properties in both the proximal and distal sections of the tendon clearly demonstrate that a new and modified matrix is formed throughout the tendon, and that a different type of matrix is formed at each site.


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3196-3196
Author(s):  
Pan Zhang ◽  
Deepa Sridharan ◽  
Michael Acosta ◽  
Muriel Lambert

Abstract Abstract 3196 Poster Board III-133 The hereditary bone marrow failure disorder, Fanconi anemia (FA), is characterized by a markedly increased incidence of acute myelogenous leukemia, diverse congenital abnormalities and a defect in ability to repair DNA interstrand cross-links. We have previously shown that in FA cells there is a deficiency in the structural protein nonerythroid a spectrin (aSpII), which is involved in repair of DNA interstrand cross-links and binds to cross-linked DNA. aSpII co-localizes in nuclear foci with FANCA and the cross-link repair protein, XPF, after normal human cells are damaged with a DNA interstrand cross-linking agent. One of the FA proteins which is thought to play an important role in the repair of DNA interstrand cross-links is FANCD2, which is known to form nuclear foci after cross-link damage. The present study was undertaken in order to get a better understanding of the relationship between aSpII and FANCD2, whether they interact with each other during the DNA repair process and co-localize in damage-induced nuclear foci. Immunofluorescence microscopy was carried out to determine whether these proteins co-localized in nuclear foci after cells were damaged with a DNA interstrand cross-linking agent, 8-methylpsoralen plus UVA light (8-MOP) or mitomycin C (MMC). Time course measurements showed that FANCD2 foci were first visible at 2 hours after damage and increased up to 16 hours and were still present at 72 hours after damage. This time course of foci formation correlated with levels of monoubiquitination of FANCD2. Measurement of gH2AX foci formation showed that the time course of foci formation was similar to that of FANCD2 measured up to 72 hours post damage. In contrast, aSpII foci were first visible between 8-10 hours after damage. The number of these foci peaked at 16 hours and by 24 hours foci were no longer observed. Co-localization studies showed that there was little co-localization of the FANCD2 and aSpII foci over this time course. This indicates that these two proteins may be involved in different steps in the DNA interstrand cross-link repair process. Based on models that have been proposed for the role of FANCD2 in the repair of DNA interstrand cross-links, we propose that, after DNA damage, FANCD2 localizes at DNA replication forks stalled at sites of interstrand cross-links and aids in the assembly of proteins at this site. This is followed by localization of aSpII and XPF and other proteins involved in the initial incision steps in DNA interstrand cross-link repair where they play a role in the unhooking of the cross-link. FANCD2 is then involved in subsequent steps in the repair process, which involve homologous recombination. Thus two proteins, FANCD2 and aSpII, both of which have been shown to be critical for the DNA interstrand cross-link repair process may be involved in different or distinct steps in this repair process. Deficiencies in these proteins would impact on DNA interstrand cross-link repair and, as we have shown for aIISp, would have an adverse effect on the genomic stability of FA cells. . Disclosures No relevant conflicts of interest to declare.


2004 ◽  
Vol 83 (10) ◽  
pp. 807-810 ◽  
Author(s):  
P.A. Miguez ◽  
P.N.R. Pereira ◽  
P. Atsawasuwan ◽  
M. Yamauchi

Several studies have indicated differences in bond strength of dental materials to crown and root dentin. To investigate the potential differences in matrix properties between these locations, we analyzed upper root and crown dentin in human third molars for ultimate tensile strength and collagen biochemistry. In both locations, tensile strength tested perpendicular to the direction of dentinal tubules (undemineralized crown = 140.4 ± 48.6/root = 95.9 ± 26.1; demineralized crown = 16.6 ± 6.3/root = 29.0 ± 12.4) was greater than that tested parallel to the tubular direction (undemineralized crown = 73.1 ± 21.2/root = 63.2 ± 22.6; demineralized crown = 9.0 ± 3.9/root = 16.2 ± 8.0). The demineralized specimens showed significantly greater tensile strength in root than in crown. Although the collagen content was comparable in both locations, two major collagen cross-links, dehydrodihydroxylysinonorleucine/its ketoamine and pyridinoline, were significantly higher in the root (by ~ 30 and ~ 55%, respectively) when compared with those in the crown. These results indicate that the profile of collagen cross-linking varies as a function of anatomical location in dentin and that the difference may partly explain the site-specific tensile strength.


1996 ◽  
Vol 271 (3) ◽  
pp. R696-R703 ◽  
Author(s):  
K. Reiser ◽  
P. Summers ◽  
J. F. Medrano ◽  
R. Rucker ◽  
J. Last ◽  
...  

Collagen biosynthesis was analyzed in C57BL/6J mice homozygous for the high-growth locus. Plasma levels of insulin-like growth factor-1 (IGF-1) were significantly elevated in high-growth mice at all ages studied (3 wk-6 mo); IGF-binding proteins were also elevated. Skin biopsies were obtained from mice aged 3, 6, and 9 wk under halothane anesthesia. Mice were killed at 6 mo of age. Collagen, expressed per weight of tissue, was significantly increased in all tissues from high-growth mice, as was collagen cross-linking, expressed as moles of cross-link per mole of collagen. Expression of types I and III collagen, lysyl oxidase, and lysyl hydroxylase was increased in all tissues analyzed. There was a preferential increase in type III expression relative to type I expression. Rate and extent of accumulation of collagen in granulation tissue were measured in polyvinyl alcohol sponges implanted subcutaneously; collagen accumulation was significantly greater in the high-growth mice. These results suggest that 1) elevated circulating IGF-1 may increase collagen deposition both in normal tissue as well as in granulation tissue by increasing collagen gene expression, 2) IGF-1 may increase collagen cross-linking by stimulating expression of lysyl oxidase, and 3) the preferential increase in dihydroxylated cross-links observed in high-growth mice may be due to the stimulation of lysyl hydroxylase expression by IGF-1. In summary, elevated levels of IGF-1 appear to affect collagen both quantitatively and qualitatively, primarily through their effects on gene expression of collagen and of those enzymes responsible for posttranslational modifications of collagen.


2020 ◽  
Vol 295 (31) ◽  
pp. 10562-10571 ◽  
Author(s):  
Melanie Stammers ◽  
Irina M. Ivanova ◽  
Izabella S. Niewczas ◽  
Anne Segonds-Pichon ◽  
Matthew Streeter ◽  
...  

Collagen is a structural protein whose internal cross-linking critically determines the properties and functions of connective tissue. Knowing how the cross-linking of collagen changes with age is key to understanding why the mechanical properties of tissues change over a lifetime. The current scientific consensus is that collagen cross-linking increases with age and that this increase leads to tendon stiffening. Here, we show that this view should be reconsidered. Using MS-based analyses, we demonstrated that during aging of healthy C57BL/6 mice, the overall levels of collagen cross-linking in tail tendon decreased with age. However, the levels of lysine glycation in collagen, which is not considered a cross-link, increased dramatically with age. We found that in 16-week-old diabetic db/db mice, glycation reaches levels similar to those observed in 98-week-old C57BL/6 mice, while the other cross-links typical of tendon collagen either decreased or remained the same as those observed in 20-week-old WT mice. These results, combined with findings from mechanical testing of tendons from these mice, indicate that overall collagen cross-linking in mouse tendon decreases with age. Our findings also reveal that lysine glycation appears to be an important factor that contributes to tendon stiffening with age and in diabetes.


2004 ◽  
Vol 19 (8) ◽  
pp. 1349-1355 ◽  
Author(s):  
Suchaya Pornprasertsuk ◽  
Wagner R Duarte ◽  
Yoshiyuki Mochida ◽  
Mitsuo Yamauchi

2018 ◽  
Vol 4 (1) ◽  
pp. 489-492
Author(s):  
Steven Melcher ◽  
Eberhard Spörl ◽  
Edmund Koch ◽  
Gerald Steiner

AbstractCorneal collagen cross-linking (CXL) with riboflavin and UVA light is a therapeutic procedure to restore the mechanical stability of corneal tissue. The treatment method applies to pathological tissue changes, such as keratoconus. It induces the photochemical formation of new collagen cross-links. Although therapeutic effects are indisputable, the exact molecular process of CXL and how cross-links are formed is still unclear. In this work, Fouriertransform infrared (FT-IR) spectroscopy is used to investigate the cross-linking process. For that purpose, in-situ experiments with porcine corneas are carried out using attenuated total reflection (ATR) spectroscopy. Furthermore, IR micro-spectroscopic imaging in transmission mode is used to investigate thin tissue sections of the cornea and initial approaches for the distinction of cross-linked and untreated tissue by IR microspectroscopic imaging were performed. Multivariate methods are applied to access changes that occur as a result of CXL. It is shown that spectral changes after cross-linking are caused predominantly by an increase of methyl- and methylene groups as well as primary and secondary amines. In addition, a decrease of carbonyl groups could be observed.


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