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Ultrastructural immunolocalization of lysyl oxidase in vascular connective tissue.

The Journal of Cell Biology (Impact Factor: 9.69). 10/1986; 103(3):1121-8.
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ABSTRACT The localization of lysyl oxidase was examined in calf and rat aortic connective tissue at the ultrastructural level using polyclonal chicken anti-lysyl oxidase and gold conjugated rabbit anti-chicken immunoglobulin G to identify immunoreactive sites. Electron microscopy of calf aortic specimens revealed discrete gold deposits at the interface between extracellular bundles of amorphous elastin and the microfibrils circumferentially surrounding these bundles. The antibody did not react with microfibrils which were distant from the interface with elastin. There was negligible deposition of gold within the bundles of amorphous elastin and those few deposits seen at these sites appeared to be associated with strands of microfibrils. Lysyl oxidase was similarly localized in newborn rat aorta at the interface between microfibrils and nascent elastin fibers. Gold deposits were not seen in association with extracellular collagen fibers even after collagen-associated proteoglycans had been degraded by chondroitinase ABC. However, the antibody did recognize collagen-bound lysyl oxidase in collagen fibers prepared from purified collagen to which the enzyme had been added in vitro. No reaction product was seen if the anti-lysyl oxidase was preadsorbed with purified lysyl oxidase illustrating the specificity of the antibody probe. The present results are consistent with a model of elastogenesis predicting the radial growth of the elastin fiber by the deposition and crosslinking of tropoelastin units at the fiber-microfibril interface.

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    • "Besides collagen, elastin fibrils are also present, particularly in the midposterior part of the human peripheral cornea (Alexander and Garner 1983; Kamma-Lorger et al. 2010). Under physiological conditions the final enzymatic step required for collagen and elastin cross-linking in the corneal stroma is catalyzed by lysyl oxidase (LOX) (Mizobe et al. 2008; Kagan et al. 1986). Recently, artificial corneal collagen cross-linking method has become regularly used for the KC stabilization. "
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    ABSTRACT: Keratoconus (KC) is an eye disease characterized by the progressive thinning and protrusion of the cornea, which results in the loss of visual acuity. This disorder remains poorly understood, although recent studies indicate the involvement of genetic and environmental factors. Recently, we have found that the distribution of the cross-linking enzyme lysyl oxidase (LOX) is markedly decreased in about 63 % of keratoconic specimens. Similarly, LOX activity is significantly reduced by 38 % compared to control tissue. Nearly 70 systemic disorders have been reported in association with KC, most of them affecting the extracellular matrix. In this review we attempted to ascertain whether any KC-associated diseases exhibit signs that may reflect LOX impairment. We hypothesized that very similar changes in the extracellular matrix, particularly at the level of collagen metabolism, including LOX impairment in mitral leaflets, may reflect an association between KC and mitral valve prolapse. Moreover, this putative association is supported by the high frequency of Down syndrome in both diseases. Among other disorders that have been found to coincide with KC, we did not find any in which the LOX enzyme may be directly or indirectly impaired. On the other hand, in cases where KC is present along with other connective tissue disorders (Marfan syndrome, Ehlers-Danlos syndrome and others), KC may not arise as a localized manifestation, but rather may be induced as the result of a more complex connective tissue disorder.
    Journal of Neural Transmission 02/2013; DOI:10.1007/s00702-013-0993-1 · 2.87 Impact Factor
    • "LOX has been shown to be expressed by a variety of cell types and tissues which include skin fibroblasts , epithelial cells, smooth muscle cells in the aorta and respiratory bronchioles, corneal and vascular endothelial cells, and chondrocytes (reviewed in Csiszar 2001). Antibodies generated against LOX have been localized to amorphous elastin and collagen fibers (Kagan et al. 1986, Baccarani-Contri et al. 1989). An increase in LOX immunoreactivity has been correlated with an increase in collagen deposition during tissue fibrosis (Chanoki et al. 1995, Di Donato et al. 1997, Kim et al. 1999, Streichenberger et al. 2001). "
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    ABSTRACT: Lysyl oxidase (LOX) and lysyl oxidase-like (LOXL) are extracellular enzymes that deaminate peptidyl lysyl residues involved in the cross-linking of fibrillar collagens and elastin. While LOX is required for the survival of newborn mice, the role of LOXL during development remains unclear. Studies have shown that the same cell types express LOX and LOXL in the same tissues, but no functional differences have been established. We have compared the immunohistochemical localization of LOX and LOXL in various tissues from normal, young adult mice. LOX and LOXL were co-localized in the skin, aorta, heart, lung, liver and cartilage, but were localized to different areas in the kidney, stomach, small intestine, colon, retina, ovary, testis and brain. LOXL expression was further examined in tissues from different developmental stages. In embryonic mice (10.5-14.5 dpc), LOXL immunostaining was abundant in the heart, liver, intestine, and neural tube. LOXL was present in most major organs in late fetal (16.5 dpc) and newborn mice, but generally diminished as animals aged. Immunoreactivity was significantly reduced in the heart, lung, kidney and liver of 2 year-old mice, but remained prevalent in the skin and tongue. LOX and LOXL were also found in the nuclei of cells in a number of tissues. These results indicate that LOXL has a role during mouse development and in the maintenance of adult tissues.
    Journal of Molecular Histology 12/2004; 35(8-9):845-55. DOI:10.1007/s10735-004-2340-1 · 1.98 Impact Factor
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    • "A putative privileged association of lysyl oxidase isoforms toward collagen or elastic fibers should be viewed in the light of divergent reports that have previously addressed this question. Using antibodies against a 32 kDa lysyl oxidase isolated from bovine aorta, which contains separable protein isoforms (Kagan et al, 1979; Williams and Kagan, 1985), Kagan et al (1986) "
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    ABSTRACT: Elastic fiber formation involves the secretion of tropoelastin which is converted to insoluble elastin by cross-linking, initiated by the oxidative deamination of lysine residues by lysyl oxidase. Five lysyl oxidase genes have been discovered. This study deals with the expression of two isoforms, LOX and LOX-like (LOXL), in human foreskin and in a human skin-equivalent (SE) model that allows the formation of elastic fibers. In this model, keratinocytes are added to a dermal equivalent made of fibroblasts grown on a chitosan-cross-linked collagen-GAG matrix. LOX and LOXL were detected by immunohistochemistry in the dermis and the epidermis of both normal skin and in a SE. This expression was confirmed by in situ hybridization on the SE. LOX and LOXL expression patterns were confirmed in human skin. The ultrastructural localization of LOXL was indicative of its association with elastin-positive materials within the SE and human skin, though interaction with collagen could not be discarded. LOX was found on collagen fibers and could be associated with elastin-positive materials in the SE and human skin. LOXL and LOX were detected in keratinocytes where LOX was mainly expressed by differentiating keratinocytes, in contrast to LOXL that can be found in both proliferating and differentiating fibroblasts. These data favor a role for LOXL in elastic fiber formation, together with LOX, and within the epidermis where both enzymes should play a role in post-translational modification of yet unknown substrates.
    Journal of Investigative Dermatology 04/2004; 122(3):621-30. DOI:10.1111/j.0022-202X.2004.22330.x · 6.37 Impact Factor
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