Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ros1 gene was detected originally by virtue of its transforming potential; the cDNA of the human protooncogene was isolated from a tumor cell line expressing the gene ectopically. It encodes a receptor-type tyrosine specific protein kinase which is closely related to sevenless in Drosophila. Here we report the novel and remarkable in vivo expression pattern of c-ros1, which was determined in the mouse. By a combination of RNase protection and in situ hybridization, we find transient c-ros1 expression during development in the kidney, intestine and lung, coinciding with major morphogenetic and differentiation events in these organs. This temporally restricted nature of expression is unusual for tyrosine kinase receptors and suggests a role for ros1 during development. Furthermore, in kidney development c-ros1 transcripts are confined to subgroups of ureter cells known to be involved directly in inductive interactions between ureter epithelium and metanephric mesenchyme. Thus, this study implicates for the first time a tyrosine kinase receptor in mesenchymal epithelial interactions and suggests a molecular basis for these important inductive events in development.
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PMID:Transient and locally restricted expression of the ros1 protooncogene during mouse development. 171 42

We generated a recombinant immunotoxin, named scFv(MGR6)-Cla, composed of the Fv region of an anti ErbB2 monoclonal antibody (MGR6) fused to clavin, a type 1 ribosome-inactivating protein (RIP) from Aspergillus clavatus. ErbB2 is a tyrosine kinase receptor which is overexpressed in most adenocarcinomas; clavin is a 17 kDa ribonuclease which inhibits protein synthesis by inactivating ribosomes. A recombinant DNA construct containing the cDNA of the single chain Fv fragment (scFv) of the MGR6 antibody fused to the clavin cDNA, was expressed at high levels in Escherichia coli as an insoluble fusion protein containing an N-terminal affinity tag of six consecutive histidine residues. Inclusion bodies were denatured and the recombinant fusion protein was purified under denaturing conditions by single-step purification using immobilised metal ion affinity chromatography (IMAC). The purified immunotoxin was renatured at high yield and histidine tag removed by digestion with enterokinase. The purity of the immunotoxin obtained after refolding was confirmed by SDS-PAGE, RP-HPLC, GPC-HPLC and N-terminal sequence analysis. Cell-free protein synthesis inhibition and binding assays showed that both clavin and scFv(MGR6) maintained their properties after refolding.
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PMID:Production and characterisation of a recombinant single-chain anti ErbB2-clavin immunotoxin. 985 10

Angiopoietins are ligands for the endothelial cell tyrosine kinase receptor Tie-2. Ang-1, the major physiological activator of Tie-2, promotes blood vessel maturation and stability. Ang-2 counteracts this effect by competitively inhibiting the binding of Ang-1 to Tie-2. Using a combined RNase protection/semiquantitative reverse transcriptase-polymerase chain reaction approach, we demonstrate that hypoxia up-regulates Ang-2 mRNA levels by up to 3.3-fold in two human endothelial cell lines. In bovine microvascular endothelial (BME) cells, the flavoprotein oxidoreductase inhibitor diphenylene iodonium (DPI) and the related compound iodonium diphenyl mimic induction of Ang-2 but not vascular endothelial growth factor (VEGF) by hypoxia; in combination with hypoxia, DPI further increases Ang-2 expression but has no effect on the induction of VEGF by hypoxia. Neither Ang-2 or VEGF was increased by cyanide or rotenone, suggesting that failure in mitochondrial electron transport is not involved in the oxygen-sensing system that controls their expression. In ischemic rat dorsal skin flaps or in the brain of rats maintained for 12 hours under conditions of hypoxia, Ang-2 mRNA was up-regulated 7.5- or 17.6- fold, respectively. VEGF was concomitantly increased, whereas expression of Ang-1, Tie-2, and the related receptor Tie-1 was unaltered. In situ hybridization localized Ang-2 mRNA to endothelial cells in hypoxic skin. These findings 1) show that up-regulation of Ang-2 by hypoxia occurs widely in endothelial cells in vitro and in vivo; 2) suggest that induction of Ang-2, but not VEGF, by hypoxia in BME cells is controlled by a flavoprotein oxidoreductase that is sensitive to iodonium compounds; and 3) point to Ang-2 and VEGF as independently regulated and selective effectors of hypoxia-induced vascular sprouting.
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PMID:Hypoxia-inducible angiopoietin-2 expression is mimicked by iodonium compounds and occurs in the rat brain and skin in response to systemic hypoxia and tissue ischemia. 1085 29

Angiogenesis is essential for tumour growth and metastasis. It is regulated by numerous angiogenic factors, one of the most important being vascular endothelial growth factor (VEGF). Recently VEGF-B, a new VEGF family member that binds to the tyrosine kinase receptor flt-1, has been identified. Although the importance of VEGF has been shown in many human tumour types, the contribution of VEGF-B to tumour neovascularization is unknown in any tumour type. This study therefore measured the mRNA level of VEGF-B and its receptor flt-1 by ribonuclease protection assay and the pattern of VEGF-B expression by immunohistochemistry in 13 normal breast samples and 68 invasive breast cancers. Flt-1 expression was significantly higher in tumours than in normal breast (p=0.02) but no significant difference was seen in VEGF-B between normal and neoplastic breast (p=0.3). There was a significant association between VEGF-B and node status (p=0.02) and the number of involved nodes (p=0.01), but not with age (p=0.7), size (p=0.6), oestrogen receptor (ER) (p=0.2), grade (p=0.5) or vascular invasion (p=0.16). No significant relationship was present between VEGF-B and flt-1 (p=0.2) or tumour vascularity (p=0.4). VEGF-B was expressed mostly in the cytoplasm of tumour cells, although occasional stromal components including fibroblasts and endothelial cells were also positive. No difference in VEGF-B expression was observed adjacent to regions of necrosis, in keeping with this VEGF family member not being hypoxically regulated. These findings suggest that VEGF-B may contribute to tumour progression by a non-angiogenic mechanism, possibly by increasing plasminogen activators and hence metastasis, as has been described in vitro. Measurement of VEGF-B together with other angiogenic factors may identify a poor prognostic patient group, which may benefit from anti-VEGF receptor therapy targeted to flt-1 (VEGFR1) as well as kdr (VEGFR2).
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PMID:VEGF-B expression in human primary breast cancers is associated with lymph node metastasis but not angiogenesis. 1124 11

Glial cell line-derived neurotrophic factor (GDNF) and neurturin (NTN) bind to GFR alpha-1 and GFR alpha-2 receptors, respectively, and their neurotrophic activity is mediated by the tyrosine kinase receptor, Ret. All these molecules were found to be expressed in primary cultures of rat glial cells, which were largely composed of astrocytes and maintained in serum-free medium. Although GDNF, NTN and Ret mRNA levels were at the limit of detection, RNase protection assays revealed relatively high amounts of GFR alpha-1 and GFR alpha transcripts. To characterize signals controlling their expression, glial cells were exposed to serum or treated with hormones acting through nuclear receptors and by activators of the cAMP or protein kinase C (PKC)-dependent pathways. Retinoic acid or 1,25-dihydroxyvitamin D3 appeared ineffective. In contrast, the 5-fold increase in GFR alpha-2 mRNA after 24 hr of treatment with 10(-10) M of tri-iodothyronine, suggests a physiological role of thyroid hormone in the regulation of this receptor in vivo. The serum induced a 7-fold increase in GFR alpha-1 mRNA levels. These changes may be mediated by the cAMP or PKC pathways because both forskolin and TPA up-regulated the GFR alpha-1 gene. Interestingly, only TPA led to a coordinated increase in the levels of GDNF, GFR alpha-1 and GFR alpha-2 mRNAs. On the other hand, NTN transcripts remained constant, irrespective of the culture conditions. Taken together, these results indicate that GDNF family ligands and their receptors are regulated in glial cells by common or independent transductional pathways, which could modulate their specific expression during brain development or in the case of trauma.
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PMID:Differential regulation of GDNF, neurturin, and their receptors in primary cultures of rat glial cells. 1131 68

Angiogenesis is coordinated with follicular cell growth in goitrogenesis. The angiopoietins, Ang-1 and Ang-2, are angiogenic growth factors acting through Tie-2, a tyrosine kinase receptor. We have examined the expression and regulation of the angiopoietins and Tie-2 in human and rat thyroids. In human goiters there was increased Tie-2 immunostaining, compared with that in normal thyroids, on both follicular and endothelial cells. In an induced goiter in rats, in situ hybridization showed increased expression of messenger ribonucleic acids (mRNAs) for Tie-2 and Ang-1 in follicular cells. As Tie-2 has previously been believed to be restricted to cells of endothelial lineage in adults, we examined its expression further in isolated follicular cells. Tie-2 and Ang-1 mRNA expression in human thyrocytes was confirmed by ribonuclease protection assay. Ang-2 mRNA was not detected in human cultures or rat thyroids. In both human follicular cell cultures and FRTL-5 cells, immunoblotting showed that Tie-2 expression was increased by TSH and agents that increased intracellular cAMP. In conclusion, we have demonstrated the expression of Tie-2 and Ang-1 in thyroid epithelial and endothelial cells, and have shown the regulation of Tie-2 by TSH and cAMP in follicular cells. Tie-2 expression is increased in goiter in both humans and rats, consistent with a role in goitrogenesis.
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PMID:Tie-2 is expressed on thyroid follicular cells, is increased in goiter, and is regulated by thyrotropin through cyclic adenosine 3',5'-monophosphate. 1139 75

Hepatocyte growth factor/scatter factor (HGF/SF) induces proliferation, motility and morphogenesis of cells that express the proto-oncogene for the tyrosine kinase receptor, c-Met. Because these cellular events occur in the endometrium during the menstrual cycle and in placenta during development, we have initiated studies of this growth factor in these tissues from macaques. Several HGF/SF alternatively spliced transcripts have been previously reported in other tissues. However, expression of HGF/SF isoforms in the endometrium has not been studied. Here we describe the relative transcript amounts of HGF/SF isoforms in the endometrium and placenta using RNase protection analyses. During these analyses, we discovered two unexpected protected bands that were found through sequence analyses to represent isoforms similar to the previously reported NK1 and NK2 except that they encode a five amino acid deletion in the first kringle domain. We designated these two isoforms as dNK1 and dNK2. Endometrium expressed all of the isoforms; however, dNK2 was consistently expressed at higher levels than NK2 transcripts. In contrast, placenta expressed NK2 and dNK2 mRNA at equal levels, and both NK1 and dNK1 were undetectable in placenta. HGF/SF function in endometrium and placenta may involve complex interactions between the isoforms of HGF/SF and those of c-Met.
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PMID:Novel hepatocyte growth factor/scatter factor isoform transcripts in the macaque endometrium and placenta. 1175 73

Insulin receptor (IR) and IGF-I receptor (IGF-IR) are structurally and functionally related and belong to the tyrosine kinase receptor family. In teleosti such as salmonids and turbot, occurrence of multiple IR and IGF-IR members has been reported, but the structures of a complete set of both IR and IGF-IR members in a single teleost species have not yet been characterized. In this study, we cloned and analysed four distinct cDNA clones for IR and IGF-IR members from the liver and kidney of the Japanese flounder (Paralichthys olivaceus). Deduced amino acid sequence analyses and phylogenetic analysis have revealed that two of them (fIR-1 and fIR-2) belong to IR members and the other two (fIGF-IR-1 and fIGF-IR-2) are IGF-IRs. fIR-1 and fIR-2 comprised 1369 and 1368 amino acid residues respectively, and fIGF-IR-1 and fIGF-IR-2 comprised 1412 and 1418 residues respectively. All the receptor proteins contained cysteine-rich domains in their alpha-subunits, and conserved each transmembrane and tyrosine kinase domains in their beta-subunits. The amino acid sequences of fIRs and fIGF-IRs showed more than 90% sequence identity with turbot IR and IGF-IR respectively. When compared with their mammalian homologues, fIGF-IR-1 and fIGF-IR-2 proteins contained large insertions at their C-termini, as was observed in the corresponding region of turbot IGF-IR. Occurrence of multiple species of mRNA for each IR and IGF-IR was suggested by Northern blot analyses. A ribonuclease protection assay revealed diverse expressions of four receptor mRNAs in a wide range of tissues including heart, liver, ovary, testis, brain, gill arch, kidney, skeletal muscle, intestine, stomach, spleen and eye of the flounder.
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PMID:Molecular cloning, identification and characterization of four distinct receptor subtypes for insulin and IGF-I in Japanese flounder, Paralichthys olivaceus. 1201 Jun 44

Immunotherapy, based on mAbs specifically directed against cancer cells, is considered a precious strategy in the fight against cancer because of its selectivity and lack of multidrug resistant effects. However, there are obstacles to the complete success of current immunotherapy such as immune responses to nonhuman or even humanized antibodies and the large size of the antibodies, which hinders their diffusion into bulky tumors. Fully human, small immunoagents, capable of inhibiting tumor growth may overcome these problems and provide safe, highly selective and effective antitumor drugs. An attractive target for immunotherapy is ErbB2, a transmembrane tyrosine kinase receptor, overexpressed on tumor cells of different origin, with a key role in the development of malignancy. An anti-ErbB2 humanized monoclonal (Herceptin) is currently used with success for breast cancer therapy; however, it can engender cardiotoxicity and a high proportion of breast cancer patients are resistant to Herceptin treatment. Anti-ErbB2 immunoagents of human origin, with potentially no or very low immunogenicity have been engineered to assemble 'compact', i.e. reduced size, antibodies, one consisting of a human single-chain antibody fragment (scFv) fused to a human RNase to construct an immunoRNase and the other made up of two human scFv molecules fused to the Fc region of a human IgG1. By choosing a human antibody fragment as the immune moiety and a human RNase as the effector moiety, an immunoRNase would be both nonimmunogenic and nontoxic, as it becomes toxic only when the scFv promotes its internalization by target cells. The alternative strategy of compact antibodies was aimed at producing therapeutic agents with an increased half-life, prolonged tumor retention and the ability to recruit host effector functions. Moreover, the bivalency of compact antibodies can be exploited to construct bispecific antibodies, as well as for other therapeutic applications.
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PMID:Human anti-ErbB2 immunoagents--immunoRNases and compact antibodies. 1922 Apr 62

The ErbB2 tyrosine kinase receptor is an attractive target for immunotherapy, as it is overexpressed in many carcinomas. ImmunoRNases, made up of a human anti-ErbB2 scFv (single chain antibody fragment) and human RNases, have been engineered to overcome the limits of immunotoxins, made up of mouse antibodies and plant or bacterial toxins, such as immunogenicity and non-specific toxicity. Here we describe the construction and characterization of a second-generation anti-ErbB2 immunoRNase, called ERB-HP-DDADD-RNase, obtained by fusing Erbicin, a human ErbB2-directed scFv, with an inhibitor-resistant variant of human pancreatic RNase (HP-DDADD-RNase). This novel immunoRNase retains both the enzymatic activity of human pancreatic RNase and the specific binding of the parental scFv to ErbB2-positive cells, showing an affinity comparable with that of the previously reported parental immunoRNase (ERB-HP-RNase). Moreover, the novel immunoRNase is endowed with an effective and selective in vitro antiproliferative action for ErbB2-positive tumor cells, which is more potent than that of the parental immunoRNase on tumor cells expressing low levels of ErbB2, due to its resistance to the RNase inhibitor. Thus, the novel immunoRNase could represent a valuable tool for ErbB2-positive cancer therapy.
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PMID:A novel fully human antitumor immunoRNase resistant to the RNase inhibitor. 2323 87


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