Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antisense gene suppression has been carried out for human ICAM-1, ELAM-1, and VCAM-1 in cultured human umbilical vein endothelial cells (HUVEC) stimulated by lipopolysaccharide, tumor necrosis factor alpha, or interleukin-1 beta. A panel of antisense phosphorothioate oligodeoxyribonucleotides (PS-ODN), complementary to mRNA or pre-mRNA of these molecules, were tested for their gene suppression activity monitored by radioimmunoassay of the respective cell surface adhesion molecules. Sequences targeted by effective antisense PS-ODNs were located throughout the mRNA and pre-mRNA. "Hot spots" of gene suppression sites for each region were observed. Shift of the PS-ODN hybridizing site upstream or downstream by a few bases resulted in drastic change of gene suppression efficiency. In addition to translation arrest and RNase H activity, a third mechanism was proposed for antisense gene suppression, involving multiple binding sites for PS-ODN and the activities of RNase H and RNases other than RNase H. Suppression of ICAM-1, ELAM-1, or VCAM-1 in HUVEC by their antisense PS-ODNs resulted in the reduction of adhesion of monocytes and U937 to HUVEC. This may suggest cooperativity among the adhesion molecule pairs in endothelial-leukocyte adhesion, since decrease of a single adhesion molecule on EC surface significantly reduced cell-cell adherence.
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PMID:Antisense gene suppression against human ICAM-1, ELAM-1, and VCAM-1 in cultured human umbilical vein endothelial cells. 755 71

We have identified 20-mer phosphorothioate oligodeoxynucleotides which potently (IC50 values of 100-200 nM) and specifically inhibit protein kinase C (PKC)-alpha mRNA and protein expression in human lung carcinoma (A549) cells. These oligonucleotides target multiple, diverse sites on PKC-alpha mRNA including the AUG translation codon and 3'-untranslated sequences. 2'-O-Methyl phosphorothioate analogs of these oligonucleotides were without effect on PKC-alpha mRNA levels, suggesting that the reduction in targeted PKC-alpha mRNA is through RNase H-mediated cleavage. One oligonucleotide, however, was effective at inhibiting PKC-alpha protein levels as a 2'-O-methyl phosphorothioate at concentrations 2-3-fold greater than its phosphorothioate/deoxy homolog. These results suggest that the ability to serve as an RNase H substrate, although not required for all oligonucleotides, certainly increases their potency. These oligonucleotides have been used to examine the role played by PKC-alpha in mediating the phorbol ester-induced changes in mRNA levels of the cell adhesion molecule ICAM-1. In A549 cells, ICAM-1 mRNA is increased 10-20-fold by treatment of cells with the phorbol ester phorbol 12-myristate 13-acetate. When PKC-alpha protein levels are depleted by oligonucleotide treatment of A549 cells, the increase in ICAM-1 expression in response to phorbol 12-myristate 13-acetate is greatly reduced, demonstrating that PKC-alpha plays a major role in this process.
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PMID:Inhibition of protein kinase C-alpha expression in human A549 cells by antisense oligonucleotides inhibits induction of intercellular adhesion molecule 1 (ICAM-1) mRNA by phorbol esters. 791 67

Alicaforsen (ISIS-2302) is an RNase H-dependent antisense inhibitor of the intercellular adhesion molecule ICAM-1 under development by Isis Pharmaceuticals, for the potential treatment of a variety of inflammatory disorders [175741]. As of April 1997 it was in phase III trials for Crohn's disease (CD); however, the trial failed and, in December 1999, the company suspended development for this indication [352801]. In October 2000, the company re-initiated development in CD [384820] and new phase III trials had begin by May 2001 [409704]. In August 2000, phase II studies of alicaforsen in an enema formulation for ulcerative colitis and a topical formulation for psoriasis were ongoing [378715]. Development of the compound for the potential treatment of rheumatoid arthritis (RA) was discontinued in 1999 [347579]. By the end of 1998, alicaforsen was in phase II trials for kidney transplant rejection. At this time, these trials were expected to finish in mid-1999 [343460]. However, they were ongoing in September 1999, although no further development has been reported for this indication since that time [338672]. In February 1995, Isis Pharmaceuticals and Boehringer Ingelheim (BI) signed a collaborative agreement on cell adhesion inhibitors, including alicaforsen [174111]. By early 1999, Isis and BI were to decide on the next developmental step for alicaforsen following further analyses of its performance against CD [292915], [315439]. Their joint development agreement was terminated in 1999; Isis regained rights to the product and by September 1999 was in talks to license alicaforsen to another partner for CD [338672]. In June 2000, Cytogenix entered into a sponsored research agreement with Baylor College of Medicine at the Texas Medical Center Houston for the use of its ssDNA expression system for the development of antisense strategies directed against intercellular adhesion molecules for the purpose of reducing lung inflammation and injury in disease states and conditions [369677]. US-05514788, and other patents, cover antisense cell adhesion molecule inhibitors [212289], [234792].
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PMID:Alicaforsen. Isis Pharmaceuticals. 1189 Mar 55

The efficiency with which small interfering RNAs (siRNAs) down-regulate specific gene expression in living cells is variable and a number of sequence-governed, biochemical parameters of the siRNA duplex have been proposed for the design of an efficient siRNA. Some of these parameters have been clearly identified to influence the assembly of the RNA-induced silencing complex (RISC), or to favour the sequence preferences of the RISC endonuclease. For other parameters, it is difficult to ascertain whether the influence is a determinant of the siRNA per se, or a determinant of the target RNA, especially its local structural characteristics. In order to gain an insight into the effects of local target structure on the biological activity of siRNA, we have used large sets of siRNAs directed against local targets of the mRNAs of ICAM-1 and survivin. Target structures were classified as accessible or inaccessible using an original, iterative computational approach and by experimental RNase H mapping. The effectiveness of siRNA was characterized by measuring the IC50 values in cell culture and the maximal extent of target suppression. Mean IC50 values were tenfold lower for accessible local target sites, with respect to inaccessible ones. Mean maximal target suppression was improved. These data illustrate that local target structure does, indeed, influence the activity of siRNA. We suggest that local target screening can significantly improve the hit rate in the design of biologically active siRNAs.
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PMID:Local RNA target structure influences siRNA efficacy: a systematic global analysis. 1584 19