Quantitative profiling of the in vivo enzymatic activity of ricin reveals disparate depurination of different pulmonary cell types.
The plant-derived toxins ricin and abrin, operate by site-specific depurination of ribosomes, which in turn leads to protein synthesis arrest. The clinical manifestation following pulmonary exposure to these toxins is that of a severe lung inflammation and respiratory insufficiency. Deciphering the pathways mediating between the catalytic activity and the developing lung inflammation, requires a quantitative appreciation of the catalytic activity of the toxins, in-vivo. In the present study, we monitored truncated cDNA molecules which are formed by reverse transcription when a depurinated 28S rRNA serves as template. We found that maximal depurination after intranasal exposure of mice to 2LD50 ricin was reached 48h, where nearly 40% of the ribosomes have been depurinated and that depurination can be halted by post-exposure administration of anti-ricin antibodies. We next demonstrated that the effect of ricin intoxication on different cell types populating the lungs differs greatly, and that outstandingly high levels of damage (80% depurination), were observed in particular for pulmonary epithelial cells. Finally, we found that the magnitude of depurination induced by the related plant-derived toxin abrin, was significantly lower in comparison to ricin, and can be attributed mostly to reduced depurination of pulmonary epithelial cells by abrin. This study provides for the first time vital information regarding the scope and timing of the catalytic performance of ricin and abrin in the lungs of intact animals.
Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, Israel.
Reut
R
Falach
Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, Israel.
Anita
A
Sapoznikov
Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, Israel.
Yoav
Y
Gal
Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, Israel.
Ofir
O
Israeli
Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, Israel.
Moshe
M
Leitner
Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, Israel.
Nehama
N
Seliger
Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, Israel.
Sharon
S
Ehrlich
Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, Israel. Electronic address: chanochk@iibr.gov.il.
Chanoch
C
Kronman
Department of Biochemistry and Molecular Genetics, Israel Institute for Biological Research, Ness-Ziona, Israel.
Tamar
T
Sabo
D000036:Abrin / Q000008:administration & dosage / Q000302:isolation & purification / Q000378:metabolism / Q000633:toxicity; D029912:Abrus / Q000201:enzymology; D000281:Administration, Intranasal; D000818:Animals; D000992:Antitoxins / Q000627:therapeutic use; D003603:Cytotoxins / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000633:toxicity*; D018076:DNA, Complementary / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D007928:Lethal Dose 50; D008168:Lung / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D011014:Pneumonia / Q000209:etiology / Q000517:prevention & control; D011041:Poisoning / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D011500:Protein Synthesis Inhibitors / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D011687:Purines / Q000378:metabolism; D012339:RNA, Ribosomal, 28S / Q000378:metabolism; D012131:Respiratory Insufficiency / Q000209:etiology / Q000517:prevention & control; D020545:Respiratory Mucosa / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D012270:Ribosomes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D012276:Ricin / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000633:toxicity*; D012278:Ricinus / Q000201:enzymology
D000992:Antitoxins; D003603:Cytotoxins; D018076:DNA, Complementary; D011500:Protein Synthesis Inhibitors; D011687:Purines; D012339:RNA, Ribosomal, 28S; D000036:Abrin; D012276:Ricin
28SrRNA; Abrin; Depurination; Lung; Ricin