scholarly journals Involvement of arginine residues in inhibition of protein synthesis by ricin A-chain

FEBS Letters ◽  
1986 ◽  
Vol 204 (2) ◽  
pp. 219-222 ◽  
Author(s):  
Keiichi Watanabe ◽  
Gunki Funatsu
Keyword(s):  
Protein Synthesis ◽  
Ricin A Chain ◽  
Inhibition Of Protein Synthesis ◽  
Arginine Residues ◽  
A Chain ◽  
Ricin A

scholarly journals Selective cytotoxicity of ricin A chain immunotoxins towards murine cytomegalovirus-infected cells.

1996 ◽  
Vol 40 (2) ◽  
pp. 470-472 ◽  
Author(s):  
B B Barnett ◽  
D F Smee ◽  
S M Malek ◽  
R W Sidwell
Keyword(s):  
Protein Synthesis ◽  
Murine Cytomegalovirus ◽  
Ricin A Chain ◽  
Selective Cytotoxicity ◽  
Inhibition Of Protein Synthesis ◽  
Infected Cells ◽  
A Chain ◽  
Ricin A

Immunotoxins were constructed by linking immunoglobulins specific for murine cytomegalovirus (MCMV) to deglycosylated ricin A chain. Toxicities toward MCMV-infected and uninfected cells were determined by measuring the inhibition of protein synthesis following a 48-h exposure to immunotoxins commencing 24 h after infection. The 50% inhibitory concentrations ranged from 0.4 to 4 micrograms/ml for infected cells and from 22 to 120 micrograms/ml for uninfected cells. Selectivity indices ranged from 30 to 157. Control immunotoxins, which were constructed identically except that the immunoglobulin moiety had no specificity toward MCMV antigens, had 50% inhibitory concentrations of 50 and 100 micrograms/ml toward infected and uninfected cells, respectively.

scholarly journals A ricin A chain-containing immunotoxin that kills human T lymphocytes in vitro

Blood ◽  
1985 ◽  
Vol 66 (4) ◽  
pp. 908-912 ◽  
Author(s):  
PJ Martin ◽  
JA Hansen ◽  
ES Vitetta
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Protein Synthesis ◽  
T Lymphocytes ◽  
Mononuclear Cells ◽  
Ricin A Chain ◽  
Human T Lymphocytes ◽  
Blood Mononuclear Cells ◽  
A Chain ◽  
Ricin A

Abstract An immunotoxin specific for human T lymphocytes was prepared by coupling an IgG2a anti-CD3 murine monoclonal antibody (64.1) to purified ricin A chain (64.1-A). Treatment of blood mononuclear cells with this immunotoxin at a concentration of 1.7 X 10(-9) mol/L for two hours at 37 degrees C in the presence of 20 mmol/L NH4Cl decreased phytohemagglutinin-stimulated protein synthesis by 95%. In addition, a sensitive culture assay showed that fewer than 0.03% T cells remained after treatment of human bone marrow mononuclear cells with 64.1-A at a concentration of 1.7 X 10(-9) mol/L. The inhibition of protein synthesis could be prevented by preincubating cells with unconjugated 64.1 antibody but not by preincubating cells with a control IgG2a antibody that binds to a different T cell antigen (CD5). At concentrations up to 1 X 10(-8) mol/L, 64.1-A had little effect on blood mononuclear cells from baboons or human myeloid precursors (CFU- GM), which do not express the CD3 antigen recognized by 64.1. Taken together, these results indicate that the toxicity of 64.1-A was specific and that 64.1-A may be a useful reagent for depleting T cells from donor marrow as a means of preventing acute graft-v-host disease after allogeneic bone marrow transplantation.

scholarly journals Ribotoxic stress response: activation of the stress-activated protein kinase JNK1 by inhibitors of the peptidyl transferase reaction and by sequence-specific RNA damage to the alpha-sarcin/ricin loop in the 28S rRNA.

1997 ◽  
Vol 17 (6) ◽  
pp. 3373-3381 ◽  
Author(s):  
M S Iordanov ◽  
D Pribnow ◽  
J L Magun ◽  
T H Dinh ◽  
J A Pearson ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Synthesis Inhibitor ◽  
28S Rrna ◽  
Synthesis Inhibitor ◽  
Ricin A Chain ◽  
Nucleoside Antibiotics ◽  
Rna Damage ◽  
A Chain ◽  
Critical Regions ◽  
Ricin A

Inhibition of protein synthesis per se does not potentiate the stress-activated protein kinases (SAPKs; also known as cJun NH2-terminal kinases [JNKs]). The protein synthesis inhibitor anisomycin, however, is a potent activator of SAPKs/JNKs. The mechanism of this activation is unknown. We provide evidence that in order to activate SAPK/JNK1, anisomycin requires ribosomes that are translationally active at the time of contact with the drug, suggesting a ribosomal origin of the anisomycin-induced signaling to SAPK/JNK1. In support of this notion, we have found that aminohexose pyrimidine nucleoside antibiotics, which bind to the same region in the 28S rRNA that is the target site for anisomycin, are also potent activators of SAPK/JNK1. Binding of an antibiotic to the 28S rRNA interferes with the functioning of the molecule by altering the structural interactions of critical regions. We hypothesized, therefore, that such alterations in the 28S rRNA may act as recognition signals to activate SAPK/JNK1. To test this hypothesis, we made use of two ribotoxic enzymes, ricin A chain and alpha-sarcin, both of which catalyze sequence-specific RNA damage in the 28S rRNA. Consistent with our hypothesis, ricin A chain and alpha-sarcin were strong agonists of SAPK/JNK1 and of its activator SEK1/MKK4 and induced the expression of the immediate-early genes c-fos and c-jun. As in the case of anisomycin, ribosomes that were active at the time of exposure to ricin A chain or alpha-sarcin were able to initiate signal transduction from the damaged 28S rRNA to SAPK/JNK1 while inactive ribosomes were not.

scholarly journals Selective destruction of nerve growth factor receptor-bearing cells in vitro using a hybrid toxin composed of ricin A chain and a monoclonal antibody against the nerve growth factor receptor.

1985 ◽  
Vol 101 (3) ◽  
pp. 1107-1114 ◽  
Author(s):  
P S DiStefano ◽  
J B Schweitzer ◽  
M Taniuchi ◽  
E M Johnson
Keyword(s):  
Protein Synthesis ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Growth Factor Receptor ◽  
Ricin A Chain ◽  
Nerve Growth ◽  
Ngf Receptor ◽  
A Chain ◽  
Ricin A

A hybrid toxin composed of ricin A chain and a monoclonal antibody directed against the rat nerve growth factor (NGF) receptor (192-IgG) was prepared using the heterobifunctional cross-linking agent N-succinimidyl-3-(2-pyridyldithio)-propionate and purified by affinity chromatography. Characterization studies showed that the hybrid, 192-s-s-A, displaced bound 125I-labeled 192-IgG from rat superior cervical ganglion (SCG) membranes with an IC50 3-5 times lower than that of unconjugated 192-IgG. When incubated with cultured rat SCG neurons, 192-s-s-A inhibited protein synthesis in a concentration-dependent fashion. The effect of 192-s-s-A on these neurons was reversed by coincubation with an excess of 192-IgG. The IC50 of 192-s-s-A on protein synthesis in rat SCG neurons was 4 nM. Intact ricin and ricin A chain inhibited protein synthesis in these neurons with IC50 values of 5 pM and 500 nM, respectively. The 192-s-s-A hybrid had no effect on mouse SCG neurons or a human melanoma cell line known to have NGF receptors. This is consistent with the finding that 192-IgG recognizes only the rat NGF receptor. Also, 192-s-s-A did not inhibit protein synthesis in primary cultures of rat skeletal muscle or Vero cells, which do not have cell surface receptors for NGF. 192-s-s-A was able to inhibit protein synthesis in PC12 cells but the potency was 10-100 times less in these cells compared to rat SCG neurons. Ricin and A chain were also 10-100 times less potent in PC12 cells than neurons. Rat SCG neurons exposed to 192-s-s-A lost their refractile appearance under phase-contrast optics, showed granular degeneration of neurites, and died. Thus the decreased protein synthesis caused by the hybrid toxin correlated with the morphological destruction of the neurons. 192-s-s-A represents a potentially powerful tool by which to selectively destroy NGF receptor-bearing cells in vitro. The hybrid toxin may prove useful as an in vivo toxin.

scholarly journals Adult T cell leukemia: a potential target for ricin A chain immunotoxins

Blood ◽  
1985 ◽  
Vol 65 (6) ◽  
pp. 1416-1421 ◽  
Author(s):  
M Kronke ◽  
JM Depper ◽  
WJ Leonard ◽  
ES Vitetta ◽  
TA Waldmann ◽  
...  
Keyword(s):  
T Cells ◽  
Protein Synthesis ◽  
T Cell ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Maximal Inhibition ◽  
Ricin A Chain ◽  
Adult T Cell Leukemia ◽  
A Chain ◽  
Ricin A

Abstract Adult T cell leukemia (ATL) is an almost uniformly fatal malignancy of mature T cells associated with human T cell leukemia/lymphoma virus type 1 (HTLV-1) infection. Cells from this leukemia are characterized by the expression of large numbers of receptors for interleukin 2 (IL- 2). In an attempt to prepare an immunotoxin with selective cytotoxicity for ATL cells, we conjugated anti-Tac, a monoclonal anti-IL-2 receptor antibody, to purified ricin A chains. Although unmodified anti-Tac had no effect on the protein synthesis of these cells, anti-Tac-ricin A chain conjugates produced half-maximal inhibition of protein synthesis in HTLV-1-infected leukemic T cell lines at concentrations of 2 to 6 X 10(-10) mol/L (ID50). An essentially identical ID50 was obtained with leukemic peripheral blood T lymphocytes isolated from two patients with ATL. In contrast, half-maximal inhibition of protein synthesis in HTLV- uninfected, IL-2 receptor-negative T and B cell lines required 200- to 1,000-fold higher concentrations of anti-Tac-ricin A chain conjugates. Both unconjugated anti-Tac and immunoaffinity-purified IL-2 completely inhibited the toxic effects of anti-Tac-ricin A, confirming the specificity of the conjugate-IL-2 receptor interaction. Clonogenic assays demonstrated that anti-Tac-ricin A chain was able to eliminate greater than 99.9% of an HTLV-1-infected T cell population at concentrations only marginally affecting IL-2 receptor-negative cells. The data presented demonstrate that anti-Tac-ricin A is selectively cytotoxic for HTLV-1-infected leukemic T cells in vitro and raises the future possibility of specific therapeutic intervention with immunotoxins in this disease.

Sign in / Sign up

Export Citation Format

Share Document