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Query: UNIPROT:P06889 (Mol)
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Myofibroblasts (myoFb) are cells responsible for fibrous tissue formation in injured systemic organs such as the heart. Cultured myoFb, obtained from rat cardiac scar tissue, express genes that encode components requisite for angiotensin (Ang) II generation, which in turn regulates myoFb collagen turnover in an autocrine/paracrine manner. In this study, we tested the hypothesis that these wound-healing fibroblast-like cells and locally generated Ang II are involved in other repairing tissue. To test this hypothesis, we used a granuloma pouch model, where a subcutaneous air sac is created followed by injection of croton oil. Pouch tissue was collected at days 4, 7, 14 and 21. The presence of myoFb was determined by immunohistochemical alpha-smooth muscle actin (alpha-SMA) labeling and collagen accumulation by picrosirius red staining. Angiotensin converting enzyme (ACE) and Ang II receptor binding were detected by in vitro quantitative autoradiography using 125I-351A and 125I[Sar1, Ile8]Ang II, respectively, while Ang II receptor subtype was defined by displacement studies using either an AT1 (losartan) or AT2 (PD123177) receptor antagonist. Cells expressing ACE were determined by immunohistochemistry. Ang II content in pouch tissue was measured by radioimmunoassay following HPLC separation while its capacity to generate Ang II was assessed in tissue bath, with and without exogenous Ang I or lisinopril, an ACE inhibitor. Collagen accumulation in pouch tissue was examined by determining hydroxyproline content in response to lisinopril, AT1 or AT2 receptor antagonists (losartan or PD123177). In pouch tissue, we found: (1) myoFb at day 4 which became more extensive at days 7, 14 and 21; (2) morphologic evidence of collagen deposition evident at day 4, which gradually became more extensive thereafter; (3) ACE and Ang II receptor binding was evident at day 4 and remained invariant on days 7, 14 and 21; (4) the predominant Ang II receptor subtype expressed was AT1; (5) myoFb express ACE and AT1 receptors; (6) picogram quantities of Ang II (per g tissue) was evident on days 7, 14 and 21; and (7) Ang II was generated from Ang I substrate. Lisinopril and losartan, but not PD123177, significantly attenuated pouch weight and accumulation of collagen. Thus, in this model of cutaneous repair, the appearance of myoFb is associated with Ang II generation that regulates fibrogenesis by AT1 receptor binding. Signals involved in the appearance of myoFb remain uncertain. Further studies are required to address the regulation of Ang II generation in pouch tissue of the rat.
J Mol Cell Cardiol 1997 Aug
PMID:Fibrous tissue and angiotensin II. 928 34

To obtain some insight into the extracellular matrix in the human placenta, we investigated the composition of collagens purified from the placentae of patients with pre-eclampsia and compared it with normal placentae. Collagen was extracted from the placentae of both normal and pre-eclampsia pregnancies during the third trimester. The relative amounts of various collagens were evaluated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The ratio of the intensity of the band corresponding to the alpha 1 (III) chain with that of the alpha 1 (I) chain in placentae of pre-eclampsia was significantly lower than in normal placentae (P < 0.05). In contrast, the ratio of the intensity of the band corresponding to the alpha 1 (V) chain with that of the alpha 1 (I) chain in placentae of pre-eclampsia was significantly higher than in normal placentae (P < 0.05). The results suggest that an increased level of type V collagen relative to type I collagen in the placentae of pre-eclampsia might be closely associated with the disturbance to trophoblastic cell functions and the supply of nutrients to the developing fetus necessary for the maintenance of pregnancy.
Mol Hum Reprod 1997 Aug
PMID:Increase in the relative level of type V collagen in the placentae of patients with pre-eclampsia. 929 58

We previously reported the isolation of zeaxanthin and zeaxanthin dipalmitate using bioactivity-guided fractionation to discover hepatoprotective components of Lycium chinense against carbon tetrachloride induced hepatotoxicity. The present study was designed to uncover the effects of zeaxanthin dipalmitate on hepatic parenchymal and nonparenchymal cells in vitro. Uptake of [3H]thymidine by cultured rat Ito cells in response to zeaxanthin dipalmitate was measured. Collagen synthesis was assessed by the collagenase digestion method. The effects of zeaxanthin dipalmitate on the formation of nitric oxide (NO) and the release of tumor necrosis factor-alpha (TNF-alpha) from Kupffer cells and peritoneal macrophages were also assayed. Zeaxanthin dipalmitate showed a significant hepatoprotective activity against carbon tetrachloride toxicity. Cellular malondialdehyde (MDA) levels declined significantly with the treatment of the compound in a concentration dependent manner. Zeaxanthin dipalmitate significantly inhibited the uptake of [3H]thymidine by Ito cells. Zeaxanthin dipalmitate also reduced collagen synthesis in Ito cells by 65.1% (p < 0.05) as compared to untreated controls. The formation of NO in either Kupffer cells or in peritoneal macrophages was significantly decreased by zeaxanthin dipalmitate in a concentration dependent manner. The release of TNF-alpha was somewhat less affected by the compound. From these results, we conclude that zeaxanthin dipalmitate exerts a potent hepatoprotective activity by inhibiting Ito cell proliferation, collagen synthesis and by inhibiting certain biochemical functions of Kupffer cells.
Res Commun Mol Pathol Pharmacol 1997 Sep
PMID:Zeaxanthin dipalmitate from Lycium chinense has hepatoprotective activity. 938 90

The collagen isotypes present at early (6 week) and late (5 month) stages of growing deer antler were isolated and identified. Pepsin-digested collagens were separated by differential salt fractionation, SDS-PAGE and Western blotting and subsequently identified by immunostaining. Cyanogen bromide digestion of antler tissue was used to establish a collagen type-specific pattern of peptides, and these were also identified by immunoblotting. Collagen type I was found to be the major collagen in both early- and late-stage antler. Collagen type II was present in the young antler in small amounts but was not confined to the soft "cartilaginous" tip of the antler. Collagen type XI was found in the pepsin digest of the young antler, but collagen type IX was not present at either stage of antler growth. Collagen type X was found in the young antler in all fractions studied. Microscopic study showed that the deer antler did not possess a discrete growth plate as found in endochondral bone growth. Unequivocal immunolocalization of the different collagen types in the antler were unsuccessful. These results show that, despite the presence in the antler of many cartilage collagens, growth does not occur through a simple endochondral process.
Comp Biochem Physiol B Biochem Mol Biol 1997 Oct
PMID:Deer antler does not represent a typical endochondral growth system: immunoidentification of collagen type X but little collagen type II in growing antler tissue. 944 Feb 22

This contribution reviews the structure and organization of collagen molecules found in cartilage and the roles that they may play in rheumatic diseases. Cartilage is unique in its physical properties and molecular composition, and contains sufficient amounts of types II, IX, X, and XI collagen to deem these molecules as "cartilage-specific." The vitreous body of the eye, a "cartilage-like" tissue is also rich in the same collagens but is type X deficient. Types VI and XII collagen are present in cartilage as well as noncartilaginous tissues. Types II, IX, and XI collagen are organized into matrix fibrils, where type II constitutes the bulk of the fibril, type XI regulates fibril size, and type IX facilitates fibril interaction with proteoglycan macromolecules. Genetic defects in these collagens can produce mild to severe developmental abnormalities, including spondyloepiphyseal dysplasia often accompanied by an accelerated form of osteoarthritis. Sensitization with collagen can produce experimental rheumatic diseases. Type II collagen induces an erosive polyarthritis in certain strains of rats, mice, and higher primates which can resemble rheumatoid arthritis and relapsing polychondritis. Type XI collagen is arthritogenic in rats but not mice; type IX induces autoimmunity in both species but not arthritis. Arthritis is initiated by complement fixing antibodies that bind to type II collagen in autologous cartilage, and the production of these antibodies is MHC restricted and T cell dependent. It is unclear whether T cells alone can induce arthritis, although they probably help sustain it. Mapping and characterizing the of T cell epitopes on type II collagen has resulted in the synthesis of small homolog and substituted peptides of type II collagen which suppress arthritis in an antigen-specific manner by a variety of routes, including mucosal. Moreover, collagen-induced arthritis has proven a valuable model to study the contribution of cytokines and other biological agents in the pathogenesis of joint injury and how they might be used to develop new therapies. Collagen autoimmunity has been implicated in the pathogenesis rheumatoid arthritis and polychondritis. Circulating antibodies to type II collagen are found in both diseases. Antibodies to types IX and XI collagen are also present in rheumatoid sera but are less prevalent. Rheumatoid cartilage and synovium contain antibodies to type II collagen at a prevalence far greater than serum, suggesting an intra-articular antigen-driven immune process. Although effective in animal models, attempts to treat rheumatoid arthritis with orally administered type II collagen have proven elusive. Different approaches using newer formulations and selected or modified oligopeptides remain to be tested and could prove effective in the treatment of the human rheumatic diseases.
J Mol Med (Berl) 1998 Mar
PMID:The cartilage collagens: a review of their structure, organization, and role in the pathogenesis of experimental arthritis in animals and in human rheumatic disease. 953 61

Collagen is a vital component of the extracellular matrix of both the heart and blood vessel walls. It acts as a scaffold to maintain myocardial shape and permit an even distribution of force, and plays a crucial role in the mechanical properties of the blood vessels. Under normal circumstances, collagen is continually being synthesized and degraded throughout life. Increased mechanical stress, which causes myocardial hypertrophy and vessel wall thickening, stimulates collagen turnover. If collagen is deposited in excess (fibrosis), tissue function can be compromised. An understanding of the mechanisms of 'mechanosignal transduction' involved in this process will enable therapeutic approaches to be devised that will prevent inappropriate collagen deposition and thereby help to preserve function.
Mol Med Today 1998 Feb
PMID:Regulation of cardiovascular collagen deposition by mechanical forces. 954 93

Wound healing is a fundamental response to tissue injury that results in restoration of tissue integrity. This end is achieved mainly by the synthesis of the connective tissue matrix. Collagen is the major protein of the extracellular matrix, and is the component which ultimately contributes to wound strength. In this work, we report the influence of Aloe vera on the collagen content and its characteristics in a healing wound. It was observed that Aloe vera increased the collagen content of the granulation tissue as well as its degree of crosslinking as seen by increased aldehyde content and decreased acid solubility. The type I/type III collagen ratio of treated groups were lower than that of the untreated controls, indicating enhanced levels of type III collagen. Wounds were treated either by topical application or oral administration of Aloe vera to rats and both treatments were found to result in similar effects.
Mol Cell Biochem 1998 Apr
PMID:Influence of Aloe vera on collagen characteristics in healing dermal wounds in rats. 956 43

Collagen V plays a major regulatory role in the formation of heterotypic fibers of the dermis and cartilaginous tissues as well as in the assembly of extracellular matrix. The pN/pN mouse, which is defective in collagen V alpha 2 gene, exhibits skeletal abnormalities, skin fragility, and alterations in the collagen fiber organization, whereas the TSK/+ mouse, which is defective in fibrillin-1, the major component of microfibrils present in the extracellular matrix, develops cutaneous hyperplasia and autoimmunity. We have studied the role of collagen V in the formation of heterotypic collagen fibers in F1 mice, which are obtained by breeding pN/pN with TSK/+ mice. Our results show that F1 progeny neither develop cutaneous hyperplasia nor produce anti-topoisomerase I autoantibodies, unlike TSK/+ mice. The diameter of the collagen fibrils in the skin is also comparable to that found in control mice. Thus, the phenotypic changes observed in the TSK mouse could be reversed by genetic complementation with a collagen V-defective mouse.
Mol Med 1998 May
PMID:Effect of targeted mutation in collagen V alpha 2 gene on development of cutaneous hyperplasia in tight skin mice. 964 85

Two mammalian receptor tyrosine kinases (DDR1 and DDR2) have extracellular domains closely related to a D. discoideum lectin, discoidin, required for cell aggregation. Here, we show that the mammalian DDR receptors bind and are activated by specific types of collagen. Stimulation of DDR receptor tyrosine kinase activity requires the native triple-helical structure of collagen and occurs over an extended period of time. Collagen activation of DDR1 induces phosphorylation of a docking site for the Shc phosphotyrosine binding domain, whose presence is controlled by alternative splicing. Activation of DDR2 by collagen results in the up-regulation of matrix metalloproteinase-1 expression. These results suggest that the discoidin-related DDR tyrosine kinases are novel collagen receptors with the potential to control cellular responses to the extracellular matrix.
Mol Cell 1997 Dec
PMID:The discoidin domain receptor tyrosine kinases are activated by collagen. 965 99

Recently, we described chronic intracellular degeneration accompanied by fibrosis as typical structural features of hibernating myocardium and we concluded that cellular degeneration as a sign of the incomplete adaptation to the reduced blood flow is characteristic of hibernation. This study has been extended by analyzing the composition of the extracellular matrix proteins of the diseased myocardium. Areas of hibernating myocardium were identified in 38 patients by angiography, multigated radionuclide ventriculography, thallium scintigraphy with reinjection and low-dose dobutamine echocardiography. These areas were biopsied at cardiac surgery and were studied by electron microscopic and immunofluorescence techniques. Electron microscopy showed an enlarged extracellular space containing numerous particles of cellular debris, macrophages, fibroblasts, homogeneous matrix material and collagen fibrils. The basement membrane of the cardiomyocytes was thickened by an augmentation of laminin, fibronectin and collagen VI, but these proteins also were present in the matrix itself. Collagen fibrils were numerous and macrophages (CD68) and fibroblasts (vimentin) were increased. In situ hybridization showed an increase in mRNA for laminin, fibronectin and collagen. This observation is consistent with the conclusion that fibrotic scar formation was occurring continuously. It is postulated that fibrosis is the consequence of myocyte loss due to chronic underperfusion in the hibernating tissue. This will further injure myocytes so that a vicious cycle is established that leads to progressive loss of structural integrity and functional capacity. Since these changes are progressive, revascularization should be performed at the earliest time point possible in patients with areas of hibernating myocardium.
Mol Cell Biochem 1998 Sep
PMID:The extracellular matrix in hibernating myocardium--a significant factor causing structural defects and cardiac dysfunction. 977 96


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