Abstract
Ricin and abrin are ribosome-inactivating proteins leading to inhibition of protein synthesis and cell death. These toxins are considered some of the most potent and lethal toxins against which there is no available antidote. Digital holographic microscopy (DHM) is a time-lapse, label-free, and noninvasive imaging technique that can provide phase information on morphological features of cells. In this study, we employed DHM to evaluate the morphological changes of cell lines during ricin and abrin intoxication. We showed that the effect of these toxins is characterized by a decrease in cell confluence and changes in morphological parameters such as cell area, perimeter, irregularity, and roughness. In addition, changes in optical parameters such as phase-shift, optical thickness, and effective-calculated volume were observed. These effects were completely inhibited by specific neutralizing antibodies. An enhanced intoxication effect was observed for preadherent compared to adherent cells, as was detected in early morphology changes and confirmed by annexin V/propidium iodide (PI) apoptosis assay. Detection of the dynamic changes in cell morphology at initial stages of cell intoxication by DHM emphasizes the highly sensitive and rapid nature of this method, allowing the early detection of active toxins.
Highlights
Ribosome inactivating proteins (RIPs) irreversibly damage ribosomes [1], leading to inhibition of protein synthesis and cell death [2]
We present the feasibility of a cell-based assay for ricin and abrin intoxication using
In order to characterize morphological changes mediated by ricin exposure, HeLa cells were seeded in six-well plates at different confluence levels (10–30%) and incubated for 4–6 h for cell adhesion
Summary
Ribosome inactivating proteins (RIPs) irreversibly damage ribosomes [1], leading to inhibition of protein synthesis and cell death [2]. RIPs with similar structures, comprised of two glycoprotein chains (A and B) of equal sizes (~30 kDa) joined by a disulfide bond. The B-chain binds to galactose residues present on various cell surface glycoproteins and glycolipids, triggering endocytosis of the toxin. The A-chain exhibits a ribonucleic acid (RNA) N-glycosidase activity which depurinates a specific adenine residue located near the 30 terminus of the 28S ribosomal RNA. This site-specific depurination event prevents binding of elongation factor 2 to the ribosome, thereby causing translational arrest [3,4]. Ricin and abrin are isolated from the seeds of castor bean plant Ricinus communis and Abrus precatorius, respectively
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
