Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cultured guinea pig bone marrow megakaryocytes were found to secrete a 92-kd collagenase that was detected by digestion of gelatin in a polyacrylamide substrate gel assay. Neither casein or bovine serum albumin were digested by this enzyme. The enzyme is a neutral metalloprotease. Its secretion is increased by thrombin (1.0 U/ml) and phorbol myristate acetate (10 ng/ml) and is unaffected by prostaglandin E1 (10 microM). In the absence of serum, gelatinase secretion is inhibited, but it can be stimulated by cytochalasin D (1.0 microgram/ml). Gelatinase activity in the medium from megakaryocytes cultured on rat tail collagen gel is decreased. Medium from megakaryocytes cultured on Matrigel contains a second gelatinase of 90 kd. Addition of the tetrapeptide RGDS to the cultures on Matrigel blocks the appearance of the 90-kd gelatinase. Platelets contained both a 92- and a 90-kd gelatinase that was detected only after thrombin activation. The results indicate that megakaryocytes can secrete a collagenase, and its secretion may be in part controlled by interaction with the extracellular matrix. The appearance of the 90-kd gelatinase may be associated with megakaryocyte maturation and platelet formation.
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PMID:Collagenase production by guinea pig megakaryocytes in vitro. 216 10

Purified human platelets were found to contain a collagenase inhibitor that is immunologically, functionally, and chromatographically identical to that produced by human skin fibroblasts. None of the other formed elements of the blood (erythrocytes, granulocytes, mononuclear cells) possessed detectable quantities of this protein. Virtually all the collagenase inhibitor contained within platelets was released following platelet activation with thrombin. Similarly, platelet activation accompanying blood clotting also resulted in the release of this protein, the ratio of plasma to serum inhibitor levels being approximately equal to 0.5. When platelets were subjected to subcellular fractionation, essentially all of the platelet-associated collagenase inhibitor was found to be located in the alpha-granule. Studies with radiolabeled inhibitor failed to detect uptake of inhibitor by platelets. Furthermore, immunologically reactive protein of similar quantity to that found in platelets was identified in human megakaryocyte lysates. Thus, the data suggest that the collagenase inhibitor is endogenously produced and stored within platelet alpha-granules. The platelet-derived collagenase inhibitor was antigenically identical to the collagenase inhibitor from human skin fibroblasts in double immunodiffusion and, like its fibroblast counterpart, inhibited collagenase on a 1:1 stoichiometric basis. When subjected to several of the chromatographic procedures utilized to purify the fibroblast protein, the platelet inhibitor behaved in an indistinguishable manner. Platelet factor 4, previously reported to be a collagenase inhibitor, was found to be immunologically unrelated to the platelet-derived collagenase inhibitor. Furthermore, platelet factor 4 displayed no collagenase inhibitory activity. Although the function of platelet-derived collagenase inhibitor is unknown, such a protein released by activated platelets may serve to regulate collagen turnover during the early stages of the inflammatory process.
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PMID:Platelet-derived collagenase inhibitor: characterization and subcellular localization. 298 37

It is proposed that interferon may be an active agent in the treatment of patients with idiopathic myelofibrosis. In this disorder the megakaryocyte cell lineage plays a major role in the deposition of bone marrow collagen by the release of growth promoting factors, including platelet-derived growth factor, which are mitogenic for fibroblast proliferation. Interferon reduces collagen deposition in the bone marrow by suppressing the activity of the proto-oncogene, which is involved in the production of growth factors from abnormal megakaryocytes and platelets. A direct myeloid cytoreductive effect of interferon upon the megakaryocyte proliferation contributes to reducing growth factor activity in the bone marrow. Finally, interferon induces monocytoid differentiation, thereby increasing bone marrow collagenase-activity. Thus, interferon has several actions, which in concert might reduce bone marrow collagen in myelofibrosis.
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PMID:Hypothesis: a possible role for interferon in the treatment of idiopathic myelofibrosis. 322 65

The pathological and ultrastructural features of the bone marrow and the kinetics of megakaryopoiesis in patients with primary myelofibrosis indicate that a vast number of developing megakaryocytes die within the bone marrow (ineffective megakaryopoiesis). This leads to an excessive concentration of megakaryocyte intracytoplasmic components in the marrow intercellular space. Current concepts of marrow collagen regulation and megakaryocyte composition lend support to the hypothesis advocating that the development of marrow fibrosis involves two megakaryocyte components: growth factor and factor 4. The growth factor stimulates fibroblast proliferation and collagen secretion while factor 4 inhibits the activity of the enzyme collagenase. The imbalance between increased collagen production and decreased collagen degradation results in an excessive deposition of collagens in bone marrow matrix.
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PMID:Pathogenesis of myelofibrosis: role of ineffective megakaryopoiesis and megakaryocyte components. 608 32

In this article current concepts on the regulation of bone marrow collagen are reviewed and a hypothesis regarding the mechanisms leading to marrow fibrosis associated with Primary Myelofibrosis (PMF) is presented. Type I and type III collagen, products of marrow fibroblasts, are the main constituents of myelofibrotic tissue and megakaryocytes are the predominant cells proliferating in PMF. There is evidence for the clonal nature of the hematopoietic cell proliferation and the secondary origin of myelofibrosis. Also, evidence exists indicating that defective megakaryocyte maturation, i.e. ineffective megakaryocytopoiesis occurs in patients with PMF. It is postulated that ineffective megakaryocytopoiesis leads to an excessive concentration of megakaryocyte components in the marrow intercellular space and that the development of marrow fibrosis involves mainly 2 megakaryocytic products: growth factor and factor 4. The growth factor stimulates fibroblast proliferation and collagen secretion. Factor 4 inhibits the activity of the enzyme collagenase. Thus, the imbalance between increased collagen production and decreased collagen degradation leads to an excessive deposition of collagens in bone marrow matrix.
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PMID:Pathophysiological mechanisms operating in the development of myelofibrosis: role of megakaryocytes. 629 27

Recently, we purified rat thrombopoietin (TPO) from plasma of irradiated rats (XRP) by measuring its activity that stimulated the production of megakaryocytes from megakaryocyte progenitor cells (CFU-MK) in vitro. We then cloned the cDNAs for rat and human TPO. In this study, we found the production of TPO by hepatocytes isolated with the collagenase perfusion method from both normal and thrombocytopenic rats, by a two-step fractionation of hepatocyte culture medium (CM). Subsequently, CM of rat hepatoma cell lines was screened for the presence of TPO; three cell lines, H4-II-E, McA-RH8994, and HTC, were found to produce TPO. According to the purification procedure for TPO from XRP, TPO was partially purified from 2 L CM of each of three cell lines with a six-step procedure. In the final reverse-phase column, TPO from each cell line was eluted with the same retention time as that from XRP, and the TPO fraction exhibited megakaryocyte colony-stimulating activity (Meg-CSA). TPO-active fraction eluted from the final reverse-phase column was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), extracted from the gel, and assayed. TPO activity from each cell line was found in the respective molecular weight region, indicating the heterogeneity of the TPO molecule. Using reverse transcriptase-polymerase chain reaction (RT-PCR), we detected the expression of TPO mRNA in hepatocytes, three hepatoma cell lines, normal rat liver, and X-irradiated rat liver. Northern blot analysis showed that TPO mRNA was expressed mainly in liver among the various organs tested. These data demonstrate that TPO is produced by rat hepatocytes and hepatoma cell lines and suggest that liver may be the primary organ that produces TPO.
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PMID:Production of thrombopoietin (TPO) by rat hepatocytes and hepatoma cell lines. 749 68

Interleukin-11 (IL-11) is a cytokine which interacts with a variety of haemopoietic and non-haemopoietic cell types. Recombinant human IL-11 (rhIL-11; oprelvekin) is produced in Escherichia coli and differs from the naturally occurring protein only in the absence of the amino-terminal proline residue. In synergy with other factors, rhIL-11 stimulates the growth of myeloid, erythroid, and megakaryocyte progenitor cells in vitro. In vivo, rhIL-11 is active in mice, rats, dogs, guinea pigs, hamsters and non-human primates, where the principal activity measured was stimulation of megakaryocytopoiesis and thrombopoiesis. rhIL-11 has shown benefit in 2 clinical trials by significantly reducing severe chemotherapy-induced thrombocytopenia. In addition to its thrombopoietic activity, rhIL-11 has also shown activity in models of acute gastrointestinal mucosal damage. rhIL-11 enhanced survival in mice following cytoablative therapy and in a hamster model of chemotherapy-induced oral mucositis, where treatment with rhIL-11 was associated with decreased mucosal damage, accelerated healing and reduced numbers of deaths. rhIL-11 is currently in clinical trials for the treatment of chemotherapy-induced mucositis. In rat models of acute colonic injury and inflammatory bowel disease, rhIL-11 treatment reduced intestinal mucosal damage and alleviated clinical signs. rhIL-11 has direct effects on activated macrophages to reduce the production of pro-inflammatory mediators. In animal models of endotoxaemia, rhIL-11 treatment reduced serum levels of pro-inflammatory cytokines and blocked hypotension. rhIL-11 increased survival in models of Gram-negative sepsis and toxic shock. Based on these studies, rhIL-11 is currently in clinical trials for treatment of Crohn's disease. Other inflammatory conditions are being further evaluated. Mechanistically, rhIL-11 functions at many levels to control inflammation, ameliorate tissue damage and maintain haemostasis in the face of trauma or infection. rhIL-11 has direct effects on hepatocytes, inducing the production of acute phase reactant proteins, haem oxygenase and tissue inhibitor of metalloproteinase-1 (TIMP-1). TIMP-1 expression can also be induced in synoviocytes and chondrocytes by treatment with rhIL-11. rhIL-11 administration has been associated with increased plasma levels of von Willebrand factor and fibrinogen. rhIL-11 treatment potentially offers multiple benefits for cancer chemotherapy patients, such as prevention of thrombocytopenia, gastrointestinal epithelial protection and subsequent reduction of mucositis, and amelioration of inflammatory complications. In addition, rhIL-11 is being evaluated further in the treatment of inflammatory disorders such as inflammatory bowel disease, rheumatoid arthritis and sepsis.
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PMID:Interleukin-11. 1803 Nov 4

Reliable markers are essential to increase our understanding of the biological features of human hematopoietic stem cells and to facilitate the application of hematopoietic stem cells in the field of transplantation and regenerative medicine. We previously identified endothelial cell-selective adhesion molecule (ESAM) as a novel functional marker of hematopoietic stem cells in mice. Here, we found that ESAM can also be used to purify human hematopoietic stem cells from all the currently available sources (adult bone marrow, mobilized peripheral blood, and cord blood). Multipotent colony-forming units and long-term hematopoietic-reconstituting cells in immunodeficient mice were found exclusively in the ESAM(High) fraction of CD34(+)CD38(-) cells. The CD34(+)CD38(-) fraction of cord blood and collagenase-treated bone marrow contained cells exhibiting extremely high expression of ESAM; these cells are likely to be related to the endothelial lineage. Leukemia cell lines of erythroid and megakaryocyte origin, but not those of myeloid or lymphoid descent, were ESAM positive. However, high ESAM expression was observed in some primary acute myeloid leukemia cells. Furthermore, KG-1a myeloid leukemia cells switched from ESAM negative to ESAM positive with repeated leukemia reconstitution in vivo. Thus, ESAM is a useful marker for studying both human hematopoietic stem cells and leukemia cells.
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PMID:ESAM is a novel human hematopoietic stem cell marker associated with a subset of human leukemias. 2677 86