Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relatively large size and dynamics of oligosaccharides can result in substantial shielding of functionally important areas of proteins to which they are attached, modulate the interactions of glycoconjugates with other molecules and affect the rate of processes which involve conformational changes. This review focuses on the occupancy of N-linked glycosylation sites on three enzymes, ribonuclease, plasminogen and tissue plasminogen activator. Each of these proteins occurs naturally as two populations of molecules, distinguished from each other only by the presence or absence of an oligosaccharide at one glycosylation site. The presence of an oligomannose sugar on ribonuclease (at Asn-34) alters its overall dynamics, increases its stability towards proteinases and decreases its functional activity towards double-stranded RNA. The N-linked sugar on plasminogen (at Asn-288) within kringle 3 reduces the rate of the beta- to alpha-conformational change, modulates the transport of plasminogen into the extravascular compartment, decreases plasminogen binding to U937 cells and downregulates the activation of plasminogen by both urokinase and tissue plasminogen activator. Additionally, in fibrinolysis, within a ternary complex of fibrin, plasminogen and tissue plasminogen activator, the N-linked sugar of plasminogen hinders the initial interaction with tissue plasminogen activator (i.e., it alters Km). The presence of an N-linked glycan (at Asn-184) in the kringle 2 domain of tissue plasminogen activator hinders the rearrangement of this ternary complex, decreasing the turnover rate (Kcat).
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PMID:The effects of variable glycosylation on the functional activities of ribonuclease, plasminogen and tissue plasminogen activator. 771 Oct 52

Rapid regeneration of the endothelium is a critical component of vascular wall repair because limitations of this process enhance early thrombotic and vasospastic complications, as well as late sequelae of recurrent lesion formation. We have postulated that direct activation of the thrombin receptor initiates both mitogenic and chemokinetic endothelial behavior which facilitates intimal repair. To characterize the role of the thrombin receptor in human endothelial cell (EC) proliferation and migration, we investigated the effects of both alpha-thrombin (0.5-10 U/ml) and its receptor-activating peptide (TRAP; 1-100 microM). Responses of human aortic (HAEC) and umbilical vein (HUVEC) were characterized using [3H]thymidine and 61Cr microcarrier bead assays of proliferation and migration, respectively. Expression of motility-related genes was evaluated using a ribonuclease protection assay. Thrombin exerts both of its chemokinetic and mitogenic effects differentially in human endothelial cells. Following 2 or 4 days in culture, HUVEC proliferation increased two- to threefold after exposure to thrombin, primarily in the low concentration range (P < 0.05). However, HACE proliferation was inhibited up to 50% after a 4-day incubation period (P < 0.005). These mitogenic effects, including the inhibition of aortic endothelial cell proliferation, were reproduced, in part, by thrombin receptor activation with TRAP. In contrast, thrombin stimulates migratory responses in HAEC, but not HUVEC. However, this behavior was not reproduced by TRAP. It is noteworthy that urokinase-plasminogen activator (u-PA) expression was much more strongly expressed in migrating HAEC than in the HUVEC population. Moreover, when stimulated with thrombin, u-PA gene expression was significantly augmented in HAEC. It has been speculated that an effective human thrombin receptor (HTR) antagonist may reduce the proliferation of vascular smooth muscle cells and the development of a restenotic lesion following arterial wall injury. Our data suggest that such an inhibitor will likely also accelerate intimal regeneration through a dominant effect on limiting the HTR inhibitory effect on endothelial proliferation.
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PMID:Endothelial cells exhibit differential chemokinetic and mitogenic responsiveness to alpha-thrombin. 918 72

Components of the extracellular matrix take part in tissue rebuilding as well as activating surface-bound growth factors. In the present study, expression and selected activities of urokinase-type plasminogen activator (uPA), matrix metalloproteinases (MMPs), their inhibitors (plasminogen activator inhibitor 1 (PAI-1) and tissue inhibitors of metalloproteinases (TIMPs)) were examined in bovine oviducts by RT--PCR, ribonuclease protection assay and activity assays. A high content of mRNA encoding for uPA was detected before ovulation with a three-fold decrease after ovulation. In contrast, PAI-1 expression appeared to be stable during the oestrous cycle. Oviductal flushings produced caseinolytic zones in zymograms containing plasminogen at approximately 50 kDa and 28 kDa. An activity assay for uPA showed highest net activity during the early to mid-luteal phase. Increased TIMP-1 and MMP-2 mRNA concentrations were found around the time of ovulation compared with the luteal phase. In contrast, MMP-1 mRNA transcripts were enriched during the early to mid-luteal phase. Gelatin zymograms detected a 70--72 kDa protease activity showing an oestrous cycle-dependent activity with highest activity before ovulation. Reverse zymography detecting TIMPs revealed proteins between 21 kDa and 24 kDa. Only for the smallest (21 kDa) protein were amounts increased around the time of ovulation compared with the luteal phase. The observation that several extracellular matrix components were regulated distinctly in bovine oviducts indicates that local interactions between these components, growth factors, gametes and the embryo are possible and may influence fertilization and early embryonic development.
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PMID:Differential expression of extracellular matrix components in the bovine oviduct during the oestrous cycle. 1142 36

We previously demonstrated doxorubicin-induced urokinase expression in human H69 SCLC cells by the microarray technique using Human Cancer CHIP version 2 (Takara Shuzo, Kyoto, Japan), in which 425 human cancer-related genes were spotted on glass plates (Kiguchi et al., Int J Cancer 2001;93:792-7). Microarray analysis also revealed significant induction of IL-8, a member of the CXC chemokines. We have, therefore, extended the observation by testing the effects of doxorubicin on expression of the chemokine family and provide here definitive evidence that doxorubicin induces IL-8 and MCP-1, one of the CC chemokines, at least in 2 human SCLC cells, H69 and SBC-1. IL-8 antigen levels, measured by ELISA, were markedly increased in both H69 and SBC-1 conditioned media after doxorubicin treatment, in parallel with mRNA levels; and this was dependent on the dose of doxorubicin. The ribonuclease protection assay, using a multiprobe template set for human chemokines, revealed induction of not only IL-8 but also MCP-1 in doxorubicin-treated H69 cells. MCP-1 antigen levels increased approximately 100-fold in doxorubicin-treated H69 cells. RT-PCR using specific primers for MCP-1 suggested that doxorubicin also induced MCP-1 expression in SBC-1 and SBC-3 SCLC cells. Futhermore, CAT analysis using IL-8 promoter implicated the PEA3 transcriptional factor, whose binding site was located immediately upstream of the AP-1 and NF-kappaB binding sites. Thus, it is suggested that doxorubicin induces IL-8 and MCP-1 chemokines in human SCLC cells by activating gene expression, in which at least PEA3 is involved. IL-8 and MCP-1 are major chemoattractants for neutrophils and monocytes/macrophages, respectively; therefore, extensive induction of IL-8 and MCP-1 may provoke the interaction between inflammatory/immune cells and tumor cells under doxorubicin stimulation and influence many aspects of tumor cell biology.
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PMID:Induction of IL-8 and monoclyte chemoattractant protein-1 by doxorubicin in human small cell lung carcinoma cells. 1247 21