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E Knight

Publications and source records attributed to E Knight.

At least 55 records · Page 3Linked to original sources
PubMed1986

Molecular characterization of the interferon-induced 15-kDa protein. Molecular cloning and nucleotide and amino acid sequence.

We have isolated a cDNA clone for an interferon-induced 15-kDa protein. The cDNA clone was prepared from mRNA isolated from interferon-beta-treated human Daudi cells. The clone of 635 base pairs contains an open reading frame coding for a protein of 145 amino acids, and suggests for the mRNA a 75-base pair 5' untranslated and a 125-base pair 3' untranslated region. Approximately 85% of the amino acid sequence of the 15-kDa protein has been independently obtained from 2 nmol of material using microsequencing technology on the N terminus of the intact protein and on tryptic and chymotryptic peptides. The amino acid sequence of the isolated protein is identical to the amino acid sequence deduced from the cDNA. Northern blot analysis confirmed that the mRNA for the 15-kDa protein is undetectable in untreated cells, but is greatly induced following interferon treatment.

Amino Acid Sequence↗
PubMed1985

Interferon regulates c-myc gene expression in Daudi cells at the post-transcriptional level.

c-myc gene mRNA is reduced by greater than 75% in the human lymphoblastoid cell line Daudi when growth is inhibited by treatment with human interferon beta (IFN-beta). In the present communication, we describe the effect of IFN-beta treatment on transcription of the c-myc gene and on the steady-state level of c-myc mRNA in the cytoplasm of Daudi cells. The results show that, although the rate of c-myc transcription is not significantly different in nuclei isolated either from untreated cells or from those treated with IFN-beta for 3 or 24 hr, the level of c-myc mRNA in the cytoplasm is reduced by 60% within 3 hr of IFN-beta treatment. These results suggest that IFN-beta regulates the c-myc mRNA at a post-transcriptional level. These results are in contrast to the regulation of two IFN-beta-induced genes that under identical conditions are regulated in these cells at the transcriptional level. We have also detected induction of the (2'-5')oligoadenylate synthetase (2-5A synthetase) gene in IFN-beta-treated Daudi cells. Since certain c-myc transcripts have the capacity to form double-stranded RNA regions, we propose that one mechanism by which c-myc could be regulated post-transcriptionally in IFN-beta-treated cells is by activating, through its own double-strandedness, the 2-5A synthetase/RNase L endonuclease system, which would cause selective degradation of the c-myc RNA.

2',5'-Oligoadenylate Synthetase↗
PubMed1985

Interferon-beta enhances the synthesis of a 20,000-dalton membrane protein: a correlation with the cessation of cell growth.

Interferons (IFNs)-alpha and -beta but not -gamma enhance the synthesis of a protein in the membranes of Daudi cells. This protein has an estimated molecular weight of 20,000 (20 kD). Furthermore, the 20-kD protein is enhanced only in the membranes of cells whose growth can be inhibited by IFN-beta (Daudi, WISH, HL-60, diploid fibroblasts) but not in the membranes of cells whose growth is not inhibited by IFN-beta (Namalva, Raji). These data suggest a correlation between the IFN-beta-enhanced 20-kD membrane protein and the inhibition of cell growth by IFN-beta.

Burkitt Lymphoma↗
PubMed1984

Interferon-induced proteins. Purification and characterization of a 15,000-dalton protein from human and bovine cells induced by interferon.

Human interferons induce a protein of 15,000 daltons in human and bovine cells. This protein is located in the cytoplasm in a soluble form and is induced by concentrations of interferon which induce the antiviral state. Messenger RNA prepared from interferon-treated human and bovine cells contains a mRNA which yields on translation in vitro a protein similar in size to the 15-kDa protein induced by interferon in vivo. The human protein has been purified to homogeneity from interferon-treated human cells by ion-exchange chromatography and reverse-phase high-performance liquid chromatography. A comparison of the peptides generated by V8 protease from the human and bovine 15-kDa proteins reveals that the two proteins are similar but not identical.

Animals↗
PubMed1984

Antibodies to synthetic peptides of human interferon-beta. Use in biosynthetic studies.

Two peptides from the amino terminus of human interferon-beta were synthesized corresponding to amino acids 1-21 and 18-45. The peptides were conjugated to bovine serum albumin, and rabbits were immunized with either the (1-21)- or the (18-45)-peptide conjugate. Antibodies to the synthetic peptides were detected in the sera using a radioimmunoassay with 125I-labeled peptide. Two of the antisera, one against peptide 1-21 and one against peptide 18-45, immunoprecipitated [35S]interferon-beta. The former was used to study the biosynthesis of interferon-beta in human diploid fibroblasts. In cells induced with double-stranded RNA (poly(I:C] to synthesize interferon-beta, two intracellular proteins with estimated molecular weights of 23,000 and 18,000 were precipitated with the antiserum. Three exocellular proteins from the same induced cells were precipitated with molecular weights of 23,000, 18,000, and 10,000. Reduced amounts of the intra- and exocellular Mr = 23,000 component and enhanced amounts of the Mr = 18,000 component were observed when induced cells were treated with the glycosylation inhibitor tunicamycin. Neither the antibody to peptide 1-21, the antibody to peptide 18-45, nor a combination of both antibodies neutralized the interferon-beta antiviral activity. We conclude that the amino terminus of interferon-beta may not be involved in the binding of interferon-beta to its receptor.

Amino Acid Sequence↗
PubMed1984

Transcriptional induction of two genes in human cells by beta interferon.

The binding of interferons to distinct cell surface receptors leads to the induction of synthesis of several unique polypeptides and their corresponding mRNAs (1-6). We have isolated two cDNAs that are complementary to nuclear RNA whose synthesis is induced from undetectable levels to maximal rates of transcription within 30-60 min after the addition of beta interferon to human fibroblasts or to HeLa cells. These results prove that a single polypeptide can, by binding to a specific plasma membrane receptor, promptly activate the transcription of a defined set of genes.

DNA↗
PubMed1984

Selective reduction of c-myc mRNA in Daudi cells by human beta interferon.

Under normal growth conditions, the human lymphoblastoid cell line Daudi expresses high levels of c-myc mRNA. These cells are also sensitive to growth inhibition by interferons. We have compared the levels of mRNA for the c-myc in untreated and human beta interferon (IFN-beta)-treated Daudi cells by RNA dot-blot and blot-hybridization analysis methods. Using a synthetic oligonucleotide complementary to the human c-myc mRNA as the probe, we detected a more than 75% reduction in the c-myc hybridizable poly(A)+ RNA in the IFN-beta-treated cells. This reduction in the c-myc mRNA appears to be selective because the level of actin mRNA is not significantly affected by the IFN-beta treatment. In addition, neither in vitro translation of mRNA extracted from IFN-beta-treated cells nor in vivo synthesis of cellular proteins in IFN-beta-treated cells are quantitatively affected. We surmise that the selective reduction in the amount of c-myc mRNA in IFN-beta-treated Daudi cells may be related to the IFN-induced inhibition of the Daudi tumor cell growth.

Cell Division↗
PubMed1982

Human interferon-beta: effects of deglycosylation.

Human fibroblast-derived interferon-beta (IFN-beta) labeled in vivo with 35S-methionine and purified to greater than 90% radiochemical purity has been used to study the effect of glycosidases on its biological activity and its molecular weight. Incubation of the radioactive interferon with the glycosidases causes a reduction in the estimated molecular weight from 23,000 to 18,000 as determined by electrophoresis on SDS-gels. There are intermediate transient sizes that are generated prior to 18,000, but not proteins are observed that are smaller than 18,000 even after prolonged incubation. The deglycosylated IFN-beta (18,000) induces the antiviral state in cells in culture and inhibits the growth of cells in culture. We conclude that the carbohydrate of IFN-beta is not essential for its biological activity on cells in culture.

Antiviral Agents↗
PubMed1981

Human fibroblast interferon. An improved purification.

Human fibroblast interferon has been purified 2,900-fold to homogeneity. The purification is achieved in two steps by chromatography on blue Sepharose. The specific activity of the homogeneous interferon is 5 X 10(8) units/mg and the yield of biological activity has ranged from 20-40%. The interferon can exist as a monomer (Mr = 20,000) and as a dimer (Mr - 40,000). The dimer can be converted to the monomer by heating in sodium dodecyl sulfate and thioglycolic acid.

Cell Line↗
PubMed1981

Characterization of radioactive human fibroblast-derived beta interferon synthesized in vivo.

Radioactive human fibroblast-derived beta interferon has been synthesized in vivo after induction of human diploid fibroblast cells with poly I:C. The radioactive protein is not synthesized and secreted by uninduced cells. It reacts with antibody made against homogeneous human beta interferon and has the same N-terminal amino acid sequence as human beta interferon.

Amino Acid Sequence↗
PubMed1980

Human fibroblast interferon: amino acid analysis and amino terminal amino acid sequence.

The purification of human fibroblast interferon has been simplified to a two-step procedure consisting of affinity chromatography on Blue Sepharose and sodium dodecyl sulfate polyacrlamide gel electrophoresis. A preliminary amino acid composition and the sequence of the 13 amino-terminal residues of homogeneous interferon prepared by this method is reported.

Amino Acid Sequence↗
PubMed1979

Vascular access for cancer chemotherapy.

Eleven bovine heterografts were utilized in the repetitive administration of chemotherapy in 10 patients with insufficient vascular access. Six grafts remained patent until the time of death and five grafts clotted from 71 to 1110 days postoperatively. Three patients are alive and well. All grafts were initially patent and no wound infections resulted. The bovine heterograft appears to be a useful adjunct for securing vascular access for patients requiring cancer chemotherapy.

Animals↗
PubMed1979

Fibroblast interferon induces synthesis of four proteins in human fibroblast cells.

Treatment of human diploid fibroblasts with fibroblast interferon for 8 hr inhibited replication of vesicular stomatitis virus. When the total cell protein of cells treated with interferon for 8 hr was compared to the total cell protein of untreated cells by two-dimensional gel electrophoresis, the interferon-treated cells were found to contain four proteins not found in untreated cells. Addition of actinomycin D to the cells concurrently with interferon inhibited the synthesis of the four proteins. We conclude that these proteins are induced by interferon and that they may be involved in the inhibition of virus replication.

Cells, Cultured↗
PubMed1978

Effects of salicylamide and protein restriction on the skeletal development of the rat fetus.

Salicylamide has previously been shown to be teratogenic to the rat. Aims of the present study were to examine separate effects and interactions of salicylamide administration and protein restriction on development of the rat fetus. In experiments using Holtzman rats,the percentage of fetal resorptions was significantly increased by drug treatment and by protein restriction. Malformations were seen in fetuses from dams given the drug from the fifth to eleventh days of gestation; the inicdence of these malformations being independent of the diet. Factors affecting appearance of ossification centers included drug dosage, placental and fetal weight and litter size. Protein restriction had no significant effect on the development of centers of ossification. It is concluded that salicylamide, as well as protein restriction, produces adverse effects on pregnancy outcome in the rat.

Abnormalities, Drug-Induced↗
PubMed1978

Considerations in our search for interferons for clinical use.

Interferon has yet to become the drug of choice for any clinical disease entity, but several promising uses are being pursued. Clinical trials are limited probably because interferon is so expensive. Cheaper interferon would probably stimulate more clinical trials. Demonstrated efficacy in a disease of considerable magnitude would spur the search for cheaper interferon. Possible ways to look for more, cheaper interferon are suggested. The need to understand the chemical and structural composition of interferon is pointed out especially the role played by carbohydrates. There is a need for a non-biological, yet sensitive quantitative measurement of interferon; development of an immune assay is suggested. The need to restudy ways to apply interferon to target tissues and the need for a standardized product for use in clinical trials are pointed out.

Drug Evaluation↗