Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.7 (plasmin)
9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of proteins previously thought to be specific for the placenta or pregnancy have been identified in the fluids bathing both the oocyte and the sperm. In many cases their concentrations in follicular fluid and seminal plasma greatly exceeded those in the serum of nonpregnant women or men, and sometimes they even exceeded the levels in pregnancy sera. We report here the occurrence of PP5, PP12, PP14 and PAPP-A in follicular fluid and seminal plasma. In follicular fluid, the levels of PP5, PP12, and PAPP-A correlate with the estrogen concentration of the same fluid, and the PP12 and PAPP-A levels also bear a positive correlation to the progesterone concentration. The levels of PP12 and PAPP-A increase as the follicle grows, as do the levels of many steroid hormones. Therefore, the apparent correlations observed may be merely coincidental. However, circumstantial evidence from other reproductive organs indicates that the synthesis of PP12 and PAPP-A is stimulated by progesterone. Results of immunohistochemical staining show that PP12 and PAPP-A are localized in the luteinized granulosa cells and the corpus luteum. Previous studies indicate that PP5 and PAPP-A inhibit the action of proteolytic enzymes plasmin and elastase, which are believed to be involved in the mechanisms of ovulation. The study of the significance of these various placental proteins for human reproduction is only at its beginning. Clearly, elucidation of their function is the key to a more fundamental understanding of their role in the events governing ovulation and implantation.
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PMID:Pregnancy proteins in seminal plasma, seminal vesicles, preovulatory follicular fluid, and ovary. 389 67

Proteolytic modification of circulating insulin-like growth factor binding protein-3 (IGFBP-3) has been described in a number of conditions. Using Western ligand blotting and SDS-PAGE analysis of fragmentation patterns of 125I-labelled IGFBP-3 and 125-labelled IGFBP-1, we have examined conditioned media from cultured human cell lines for the presence of proteolytic activity and compared this with the action of circulating proteases and with characterized enzymes including cathepsin D, kallikrein, plasmin and tissue plasminogen activator. 125I-Labelled IGFBP-3 was incubated with serum from pregnant women, patients following heart surgery and patients with cancer of the breast, lung or head/neck. Following separation of the preincubated samples by SDS-PAGE, a distinct pattern of degradation fragments was observed which was similar in all cases. This proteolytic activity was inhibited in the presence of EDTA, phenanthroline and 4(-2-aminoethyl)-benzenesulphonylfluoride, HCl. These proteases had no detectable effect on IGFBP-1. Serum-free conditioned medium from a human dermal fibroblast cell line, a rabdomyosarcoma, a cervical, a bladder, a chorio- and two-tongue squamous cell carcinoma cell lines all contained proteolytic activity which fragmented IGFBP-3. The pattern of fragments was similar in all cell lines but different from that produced by the circulating proteases. Six out of nine cell lines produced protease(s) which degraded IGFBP-1 in addition to IGFBP-3. Whilst all the characterized enzymes tested also fragmented IGFBP-3 and plasmin cleaved IGFBP-1, none of these acted in the same way as either circulating or cell line-derived proteolytic activity. The activity associated with the characterized enzymes and cell lines was inhibited in the presence of serum from normal healthy subjects. These results demonstrate that the serum of pregnant women, post-operative patients and patients with cancer contain circulating proteases which cause fragmentation of IGFBP-3 but have little effect on IGFBP-1. Cell-derived proteases were shown to act on IGFBP-3 and IGFBP-1 in a number of instances but are not active in the presence of circulating inhibitors. These proteases may play an important role in regulating the availability of IGFs to normal and neoplastic tissues.
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PMID:Proteolytic modification of insulin-like growth factor-binding proteins: comparison of conditioned media from human cell lines, circulating proteases and characterized enzymes. 750 92

The insulin-like growth factors, IGF-I and IGF-II, are proteins that promote cellular growth and differentiation of various organs, including the kidney. These peptides interact with high affinity cell surface receptors and bind to a family of IGF-binding proteins (IGFBPs). Altered serum and urinary IGFBP patterns in children with chronic renal failure have been previously described. In this study, we evaluated serum and urinary IGFBP profiles in acute renal failure patients (ARF; n = 10) and chronic renal failure patients (n = 10), using Western ligand blots. Most patients with acute or chronic renal failure showed decreased intact serum IGFBP-3 and increased serum IGFBP-2. Both groups displayed marked urinary IGFBP alterations, including increased urinary IGFBP-1 and totally absent urinary IGFBP-3, as detected by Western ligand blot. To evaluate altered IGFBP profiles, we performed IGFBP-3 protease assays with sera and urine from renal failure patients and normal controls. Although control urine had only minor protease activity (defined by the ability to degrade [125I]IGFBP-3), significant protease activity was found in urine from renal failure patients. The proteolytic pattern and susceptibility to protease inhibitors in most renal failure urine samples were the same as those seen in normal urine and with plasmin. Protease activity was completely inhibited by serine protease inhibitors. We speculate that urinary protease activity is mediated primarily by a serine protease(s), which may be involved in the modulation of renal IGF activity in health and disease.
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PMID:Alteration in insulin-like growth factor-binding proteins (IGFBPs) and IGFBP-3 protease activity in serum and urine from acute and chronic renal failure. 752 35

Insulin-like growth factors (IGF-I and IGF-II) in biological fluids bind to high-affinity binding proteins (IGFBP-1 to -6), which transport them and regulate their activities. Limited proteolysis of certain IGFBPs plays a major role in this regulation. IGFBP-3 is proteolysed in vivo and in several cell lines by serine proteases, including plasmin. In earlier studies we reproduced this proteolysis in vitro using recombinant human non-glycosylated IGFBP-3. Two major fragments were obtained, the larger retaining weak affinity for IGF-I and weakly inhibiting IGF I mitogenic effects. The smaller fragment, though lacking affinity for IGFs, is a potent growth inhibitor. These proteolytic fragments were isolated by HPLC and their N-terminal amino acids sequenced. Both major fragments contain the N-terminal region of the intact protein, the larger form corresponding to residues 1-160, and the smaller form, to residues 1-95. Kinetics experiments using the MG-63 osteoblast-like cell line showed that the larger peptide is generated before the smaller peptide, the latter probably being a product of secondary proteolysis of the former. Our data suggest that proteolysis of IGFBP-3 is intimately linked to its biological function. We propose a model for its action at cellular level.
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PMID:Proteolytic fragments of insulin-like growth factor binding protein-3: N-terminal sequences and relationships between structure and biological activity. 933 97

Previous studies established the existence of an FSH-inducible rat granulosa cell-derived insulin-like growth factor binding protein (IGFBP)-5 endopeptidase. It was the objective of this communication to characterize this activity in some detail. Exposure of [125I]rhIGFBP-5 substrate to media conditioned by FSH-treated granulosa cells (a cell-free assay) produced two rhIGFBP-5 cleavage products (estimated size 19.5 and 17.5 kDa). The acquisition of IGFBP-5 endopeptidase activity in culture proved FSH (or PMSG) to be dose and time dependent. The addition of oFSH or rhFSH to the cell-free assay in turn, proved without effect on IGFBP-5 endopeptidase activity, thereby arguing against the possibility of an FSH receptor-independent phenomenon or of contaminating pituitary-derived contribution. The ability of FSH to induce IGFBP-5 endopeptidase activity proved relatively specific in that other granulosa cell agonists such as activin-A, IGF-I, GnRH, interleukin-1beta, TNF alpha, TGF beta1, EGF, or endothelin-1 failed to do so. However, the concurrent provision of GnRH, TNF alpha, EGF, or endothelin-1 proved inhibitory to the IGFBP-5 endopeptidase-inducing property of FSH. Activin-A and TGF beta1 in turn further stimulated the FSH effect. Sensitivity to EDTA, 1,10 phenanthroline, and high concentrations (> or = 0.1 mM) of Zn2+ suggested a Zn2+ metalloprotease. Insensitivity to TIMP-1 and TIMP-2 argued against a matrix metalloprotease (MMP). Relative insensitivity to PMSF, AMPSF, aprotinin, TPCK, and benzamidine argued against the possibility of a serine protease. Insensitivity to pepstatin A and E64 argued against aspartic and cysteine proteases, respectively. Insensitivity to plasminogen activator inhibitor-1 (PAI-1) and the presumed lack of free plasminogen in serum-free culture media argued against plasmin. Proteolysis was completely inhibited over the acid pH range but proceeded unencumbered at neutral and basic pH. Competition studies using unlabeled IGFBPs (1-6) as well as cell-free proteolysis assays of [125I]-labeled IGFBP-1, 2, 3, and 6 suggested a significant level of specificity for the FSH-induced/IGFBP-5-directed endopeptidase. Centricon-mediated fractionation of FSH-conditioned media revealed the IGFBP-5 endopeptidase activity in the fraction representing proteins of molecular weight >100K. Taken together, these observations document a secreted, granulosa cell-derived, high molecular weight, FSH-inducible, IGFBP-5-selective, neutral/basic pH-favoring, non-MMP Zn2+ metalloprotease.
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PMID:Characterization and hormonal regulation of a rat ovarian insulin-like growth factor binding protein-5 endopeptidase: an FSH-inducible granulosa cell-derived metalloprotease. 949 60

TGF-beta has been implicated in scarring and tissue fibrosis. Most cells secrete TGF-beta as a high molecular weight, latent complex that must be processed to a lower molecular weight, biologically active form. A number of molecules are involved in this activation step including the mannose 6-phosphate/insulin-like growth factor-II receptor, tissue transglutaminase, thrombospondin, plasmin, and others. Here we describe a rapid macrophage-based system for TGF-beta1 activation, which could be used for screening potential anti-fibrotic agents. The system employs transformed mouse peritoneal macrophages treated with lipopolysaccharide as a cell line capable of activating latent TGF-beta. The activation mechanism in our system involves mannose 6-phosphate/insulin-like growth factor-II receptor and transglutaminase. The activation of latent TGF-beta in this system can be prevented by the addition of mannose-6-phosphate but not mannose-1-phosphate. In addition, transglutaminase inhibitors, antibodies to thrombospondin, insulin-like growth factor-II in the presence of its binding protein IGFBP-2, but not IGFBP-1, suppressed the activation of TGF-beta. Anti-inflammatory molecules, such as hydrocortisone, when added to LPS-treated macrophages, inhibited TGF-beta activation by a mechanism, that may involve downregulation of transglutaminase expression. In summary, this new, rapid and reproducible system allows testing molecules for their ability to inhibit TGF-beta activation, thus providing a screening method for potential anti-scarring molecules.
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PMID:Characterization of a macrophage-based system for studying the activation of latent TGF-beta. 1073 58

Posttranslational modifications, particularly proteolysis, may play a significant role in the regulation of insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) physiology, and thus, measurement of modified variants of IGFBP-3 and/or their combination ratios may have important research and diagnostic relevance. Based on evaluation of a panel of monoclonal and polyclonal IGFBP-3 antibodies, we constructed three new enzyme-linked immunosorbent assays (ELISAs) using a common capture and polyclonal (ELISA-3) or monoclonal (ELISA-1 and -2) detection antibodies and evaluated them in a two-step colorimetric procedure. Evaluation of ELISA-1-3 demonstrated detection limit, dynamic range, overall precision, and recovery of the added IGFBP-3 to be generally less than 0.04 microg/L, 2-100 microg/L, less than 10%, and 91-113%, respectively. IGF-I and -II, and IGFBP-1, -2, -4, -5, and -6 did not interfere. In normal adult sera (n = 26), seminal plasma (n = 14), pregnancy sera (n = 30), and amniotic fluid (n = 30), ELISA-1-3 detected significantly different IGFBP-3 levels (by up to 6-fold, on the average), whereas levels in seminal plasma determined by ELISA-1 were undetectable. Comparison of the values obtained vs. corresponding levels by an established method (Diagnostic Systems Laboratories, Inc., active IGFBP-3 ELISA) were similarly sample dependent and, on the average, varied by up to 19-fold. Only ELISA-3 compared well with the Diagnostic Systems Laboratories, Inc., IGFBP-3 ELISA when samples from normal adults were analyzed. The observed variability could not be totally explained by 50% lower reactivity of ELISA-1-3 for glycosylated IGFBP-3 vs. the nonglycosylated form, and changes in phosphorylation had no effect on immunoreactivity. Evaluation of IGFBP-3 after proteolysis by seminal plasma, plasmin, or thrombin suggested recognition of intact IGFBP-3 by ELISA-1, whereas ELISA-3 appeared to measure intact and proteolyzed IGFBP-3 (total IGFBP-3) with similar potency. In contrast, levels determined by ELISA-2 increased severalfold, indicating preferential recognition of IGFBP-3 fragments. We propose that immunoassay capable of differential determination of IGFBP-3 variants may help better define the physiological importance and potential clinical value of IGFBP-3 measurements.
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PMID:Immunoassay of insulin-like growth factor-binding protein-3 (IGFBP-3): new means to quantifying IGFBP-3 proteolysis. 1085 72

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