scholarly journals Intracellular Transport and Cytotoxicity of the Protein Toxin Ricin

Toxins ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 350 ◽  
Author(s):  
Natalia Sowa-Rogozińska ◽  
Hanna Sominka ◽  
Jowita Nowakowska-Gołacka ◽  
Kirsten Sandvig ◽  
Monika Słomińska-Wojewódzka
Keyword(s):  
Cell Death ◽  
Protein Synthesis ◽  
Host Cell ◽  
Intracellular Transport ◽  
Ricinus Communis ◽  
Yeast Cells ◽  
Protein Toxin ◽  
Inhibition Of Protein Synthesis ◽  
A Chain ◽  
Golgi Network

Ricin can be isolated from the seeds of the castor bean plant (Ricinus communis). It belongs to the ribosome-inactivating protein (RIP) family of toxins classified as a bio-threat agent due to its high toxicity, stability and availability. Ricin is a typical A-B toxin consisting of a single enzymatic A subunit (RTA) and a binding B subunit (RTB) joined by a single disulfide bond. RTA possesses an RNA N-glycosidase activity; it cleaves ribosomal RNA leading to the inhibition of protein synthesis. However, the mechanism of ricin-mediated cell death is quite complex, as a growing number of studies demonstrate that the inhibition of protein synthesis is not always correlated with long term ricin toxicity. To exert its cytotoxic effect, ricin A-chain has to be transported to the cytosol of the host cell. This translocation is preceded by endocytic uptake of the toxin and retrograde traffic through the trans-Golgi network (TGN) and the endoplasmic reticulum (ER). In this article, we describe intracellular trafficking of ricin with particular emphasis on host cell factors that facilitate this transport and contribute to ricin cytotoxicity in mammalian and yeast cells. The current understanding of the mechanisms of ricin-mediated cell death is discussed as well. We also comment on recent reports presenting medical applications for ricin and progress associated with the development of vaccines against this toxin.

scholarly journals Bacterial Ribonuclease MazF-Mediated Apoptosis as Potential Cancer Therapy

2021 ◽  
Author(s):  
Maryam Saffarian Abbas Zadeh ◽  
Rebecca Anne MacPherson ◽  
Guohui Huang ◽  
Hui Ding ◽  
Rhonda Reigers Powell ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Synthesis ◽  
Cell Lines ◽  
Mrna Translation ◽  
Protein Translation ◽  
Programmed Death ◽  
Inhibition Of Protein Synthesis ◽  
Cancer Agent ◽  
Cell Suicide ◽  
The Impact

Abstract Programmed cell death is a dynamic and critical mechanism of cell suicide in eukaryotes and prokaryotes. MazF is a ribonuclease protein involved in bacterial intracellular programmed death. This protein cleaves mRNAs at ACA sequences, leading to inhibition of protein synthesis and triggering cell death. Given that cancer is heterogenic and has varied susceptibility to treatment, we examined the impact of MazF proteins on the growth and viability of three cancer cell lines: MCF7, HT29, and AGS. These cell lines were transfected with ACA-less mazF mRNAs and evaluated for MazF-mediated cell death. The data illustrated that efficient MazF translation leads to a significant reduction in cell viability and is modulated by structural elements of ACA-less mazF mRNAs. In the presence of MazF, the levels of activated caspase-3 and -7 were significantly elevated in transfected cells, confirming the occurrence of apoptosis. We also quantified mRNA translation on a single-cell basis in MCF7 and AGS cell lines to examine MazF-mediated inhibition of protein synthesis. MazF expression significant decreases the levels of protein translation in the examined cell lines. This is the first report of MazF as a potential anti-cancer agent via induction of apoptosis in MCF7, AGS, and HT-29 cell lines.

Chinese Hamster Cell Variants Resistant to the A Chain of Ricin Carry Altered Ribosome Function

1982 ◽  
Vol 2 (6) ◽  
pp. 599-606
Author(s):  
Mayumi Ono ◽  
Michihiko Kuwano ◽  
Kei-Ichi Watanabe ◽  
Gunki Funatsu
Keyword(s):  
Protein Synthesis ◽  
Cell Lines ◽  
Cho Cells ◽  
Ricinus Communis ◽  
Ribosomal Subunit ◽  
Chinese Hamster ◽  
Resistant Cell ◽  
Cytotoxic Action ◽  
A Chain ◽  
Ricin A

Ricin, a toxic lectin from Ricinus communis , is composed of two different polypeptide chains, A and B, and the ricin A chain (RA) blocks protein synthesis. We studied cell lines resistant to cytotoxic action of RA. One low-RA-resistant cell line, AR10, isolated from Chinese hamster ovary (CHO) cells, was resistant to a low dose of RA (1 μg/ml) and showed a 10-fold-higher resistance to RA and ricin than that of CHO. We further mutagenized AR10 to isolate high-RA-resistant cell lines AR100-6, AR100-9, and AR100-13, which were resistant to higher doses of RA and ricin (100- to 1,000-fold) than CHO was. The binding of [ 125 I]ricin to AR10, AR100-6, AR100-9, and AR100-13 cells was decreased to about 30% of that of CHO. The internalization of [ 125 I]ricin in AR10 cells and in the high-RA-resistant clones was the same. Polyuridylate-dependent polyphenylalanine synthesis, using S-30 extracts from either AR100-9 or AR100-13, was about 100-fold more resistant to the inhibitory action of RA than when CHO, AR10, and AR100-6 cells extracts were used. The protein synthesis with ribosomes (80S) from AR100-9 or AR100-13 was 10- to 100-fold more resistant to RA than it was with parental ribosomes when combined with the S-100 fraction of CHO cells. The polyphenylalanine synthesis assay using the ribosomes constituted from the 60S subunit of AR100-9 and the 40S subunit of CHO indicated that the resistant phenotype of AR100-9 cells is due to an alteration of the 60S ribosomal subunit.

scholarly journals Chinese Hamster Cell Variants Resistant to the A Chain of Ricin Carry Altered Ribosome Function

1982 ◽  
Vol 2 (6) ◽  
pp. 599-606 ◽  
Author(s):  
Mayumi Ono ◽  
Michihiko Kuwano ◽  
Kei-Ichi Watanabe ◽  
Gunki Funatsu
Keyword(s):  
Protein Synthesis ◽  
Cell Lines ◽  
Cho Cells ◽  
Ricinus Communis ◽  
Ribosomal Subunit ◽  
Chinese Hamster ◽  
Resistant Cell ◽  
Cytotoxic Action ◽  
A Chain ◽  
Ricin A

Ricin, a toxic lectin fromRicinus communis, is composed of two different polypeptide chains, A and B, and the ricin A chain (RA) blocks protein synthesis. We studied cell lines resistant to cytotoxic action of RA. One low-RA-resistant cell line, AR10, isolated from Chinese hamster ovary (CHO) cells, was resistant to a low dose of RA (1 μg/ml) and showed a 10-fold-higher resistance to RA and ricin than that of CHO. We further mutagenized AR10 to isolate high-RA-resistant cell lines AR100-6, AR100-9, and AR100-13, which were resistant to higher doses of RA and ricin (100- to 1,000-fold) than CHO was. The binding of [125I]ricin to AR10, AR100-6, AR100-9, and AR100-13 cells was decreased to about 30% of that of CHO. The internalization of [125I]ricin in AR10 cells and in the high-RA-resistant clones was the same. Polyuridylate-dependent polyphenylalanine synthesis, using S-30 extracts from either AR100-9 or AR100-13, was about 100-fold more resistant to the inhibitory action of RA than when CHO, AR10, and AR100-6 cells extracts were used. The protein synthesis with ribosomes (80S) from AR100-9 or AR100-13 was 10- to 100-fold more resistant to RA than it was with parental ribosomes when combined with the S-100 fraction of CHO cells. The polyphenylalanine synthesis assay using the ribosomes constituted from the 60S subunit of AR100-9 and the 40S subunit of CHO indicated that the resistant phenotype of AR100-9 cells is due to an alteration of the 60S ribosomal subunit.

scholarly journals Properties of a Revertant of Escherichia coli Viable in the Presence of Spermidine Accumulation: Increase in l-Glycerol 3-Phosphate

2001 ◽  
Vol 183 (15) ◽  
pp. 4493-4498 ◽  
Author(s):  
V. Samuel Raj ◽  
Hideyuki Tomitori ◽  
Madoka Yoshida ◽  
Auayporn Apirakaramwong ◽  
Keiko Kashiwagi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Death ◽  
Protein Synthesis ◽  
Glycerol Kinase ◽  
High Concentration ◽  
Gene Encoding ◽  
E Coli ◽  
Inhibition Of Protein Synthesis ◽  
High Concentrations ◽  
Ribosome Modulation Factor

ABSTRACT Escherichia coli CAG2242 cells are deficient in thespeG gene encoding spermidine acetyltransferase. When these cells were cultured in the presence of 0.5 to 4 mM spermidine, their viability was greatly decreased through the inhibition of protein synthesis by overaccumulation of spermidine. When the cells were cultured with a high concentration of spermidine (4 mM), a revertant strain was obtained. We found that a 55-kDa protein, glycerol kinase, was overexpressed in the revertant and that synthesis of a ribosome modulation factor and the RNA polymerase ς38 subunit, factors important for cell viability, was increased in the revertant. Levels of l-glycerol 3-phosphate also increased in the revertant. Transformation of glpFK, which encodes a glycerol diffusion facilitator (glpF) and glycerol kinase (glpK), to E. coli CAG2242 partially prevented the cell death caused by accumulation of spermidine. It was also found that l-glycerol 3-phosphate inhibited spermidine binding to ribosomes and attenuated the inhibition of protein synthesis caused by high concentrations of spermidine. These results indicate that l-glycerol 3-phosphate reduces the binding of excess amounts of spermidine to ribosomes so that protein synthesis is recovered.

Über den Gehalt an membrangebundenen und freien Ribosomen in Saccharomyceszellen nach Hemmung der Proteinsynthese mit Cycloheximid / The Content of Membrane-Bound and Free Ribosomes in Saccharomyces after the Inhibition of Protein Synthesis with Cycloheximid

1978 ◽  
Vol 33 (3-4) ◽  
pp. 299-300 ◽  
Author(s):  
Joan Kraft-Creech ◽  
Ingrid Pietsch ◽  
Ernst-Randolf Lochmann
Keyword(s):  
Protein Synthesis ◽  
Untreated Control ◽  
Yeast Cells ◽  
Inhibition Of Protein Synthesis ◽  
Membrane Bound

Abstract After the inhibition of protein synthesis in Saccharomyces cells with cycloheximid, the content of membrane-bound ribosomes decreases significantly, whereas the content of free ribosomes remains the same as the untreated control for a longer period of time. This is further evidence that in yeast cells protein synthesis takes place only on membrane-bound ribosomes.

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