Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.73 (urokinase-type plasminogen activator)
 10,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Amphoterin is a heparin-binding protein that is developmentally regulated in brain and functionally involved in neurite outgrowth. Unexpectedly, amphoterin has a high mobility group 1 (HMG1)-type sequence. In the present study we have expressed amphoterin cDNA in a baculovirus vector and produced antibodies against the recombinant protein and several synthetic peptides. It was found that the amphoterin cDNA encodes the 30-kDa form of the protein isolated from tissues, whereas the co-purifying 28- and 29-kDa proteins (p28 and p29) have closely related but distinct primary structures. Partial amino acid sequencing shows several local changes in the sequences of p28 and p29 compared with amphoterin, suggesting the occurrence of a multigene family that encodes at least three different HMG1-type sequences in the rat. Studies using the probes that discern amphoterin from the other HMG1-type proteins indicate a high level expression in various transformed cell lines. Immunostaining of cells with the amphoterin-specific antibodies indicates a cytoplasmic localization that becomes remarkably enriched at the leading edges in spreading and motile cells. An extracellular localization is suggested by immunostaining of nonpermeabilized cells and by a plasminogen-dependent degradation of amphoterin in the substratum-attached material of cells. Tissue-derived and recombinant amphoterins strongly enhance the rate of plasminogen activation and promote the generation of surface-bound plasmin both by tissue-type and urokinase-type plasminogen activators. The results suggest an extracellular function for amphoterin in the leading edge of various invasive cells.
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PMID:Amphoterin, the 30-kDa protein in a family of HMG1-type polypeptides. Enhanced expression in transformed cells, leading edge localization, and interactions with plasminogen activation. 836 13

Proteases like urokinase-type plasminogen activator (uPA) play an important role in tumor invasion. Cells derived from ultraviolet radiation (UVR)-induced corneal sarcomas of Monodelphis domestica produce relatively high levels of uPA compared to the untransformed keratocytes suggesting a mechanism for their invasiveness. Because UVR is known to stimulate uPA production in many cell types, UVR exposure may further increase uPA expression in corneal tumor cells, thus enhancing their ability to infiltrate. We investigated control of basal uPA levels and the induction of uPA by UVR in transformed and untransformed corneal keratocytes from Monodelphis. These studies took advantage of the fact that Monodelphis possesses an active photolyase that can be stimulated to remove UVR-induced pyrimidine dimers by exposure to long-wavelength visible photoreactivating light (PRL). Our studies showed that significant induction of uPA occurred in response to 200 J/m2 UVR. This induction was partially blocked by treatment with PRL, indicating that DNA damage, the pyrimidine dimer in particular, played a role in uPA induction. In untransformed cultured corneal fibroblasts, the heparin-binding protein inhibitor, suramin, reduced basal uPA levels, UVR-induced uPA production and cell proliferation. Basic fibroblast growth factor, a heparin-binding growth factor known to be UVR-inducible in mesenchymal cells, stimulated uPA production and cell proliferation; however, anti-bFGF antibodies did not significantly decrease proliferation or basal uPA production. These findings suggested that basal levels of uPA secretion were modulated in response to heparin-binding growth factors and that these growth factors may also have mediated the effect of UVR on uPA levels.
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PMID:Urokinase activity in corneal fibroblasts may be modulated by DNA damage and secreted proteins. 1128 Oct 30