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Toxins 2014, 6(1), 33-53; doi:10.3390/toxins6010033
Article

Novel Class of Potential Therapeutics that Target Ricin Retrograde Translocation

1,†
, 1
, 2
, 2
, 2
 and 1,*
Received: 1 October 2013; in revised form: 11 December 2013 / Accepted: 16 December 2013 / Published: 23 December 2013
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Abstract: Ricin toxin, an A-B toxin from Ricinus communis, induces cell death through the inhibition of protein synthesis. The toxin binds to the cell surface via its B chain (RTB) followed by its retrograde trafficking through intracellular compartments to the ER where the A chain (RTA) is transported across the membrane and into the cytosol. Ricin A chain is transported across the ER membrane utilizing cellular proteins involved in the disposal of aberrant ER proteins by a process referred to as retrograde translocation. Given the current lack of therapeutics against ricin intoxication, we developed a high-content screen using an enzymatically attenuated RTA chimera engineered with a carboxy-terminal enhanced green fluorescent protein (RTAE177Qegfp) to identify compounds that target RTA retrograde translocation. Stabilizing RTAE177Qegfp through the inclusion of proteasome inhibitor produced fluorescent peri-nuclear granules. Quantitative analysis of the fluorescent granules provided the basis to discover compounds from a small chemical library (2080 compounds) with known bioactive properties. Strikingly, the screen found compounds that stabilized RTA molecules within the cell and several compounds limited the ability of wild type RTA to suppress protein synthesis. Collectively, a robust high-content screen was developed to discover novel compounds that stabilize intracellular ricin and limit ricin intoxication.
Keywords: ricin toxin; small molecule inhibitors; high-content screen; retrograde translocation; stabilization; dislocation; egfp; ribosome-inactivating protein ricin toxin; small molecule inhibitors; high-content screen; retrograde translocation; stabilization; dislocation; egfp; ribosome-inactivating protein
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Redmann, V.; Gardner, T.; Lau, Z.; Morohashi, K.; Felsenfeld, D.; Tortorella, D. Novel Class of Potential Therapeutics that Target Ricin Retrograde Translocation. Toxins 2014, 6, 33-53.

AMA Style

Redmann V, Gardner T, Lau Z, Morohashi K, Felsenfeld D, Tortorella D. Novel Class of Potential Therapeutics that Target Ricin Retrograde Translocation. Toxins. 2014; 6(1):33-53.

Chicago/Turabian Style

Redmann, Veronika; Gardner, Thomas; Lau, Zerlina; Morohashi, Keita; Felsenfeld, Dan; Tortorella, Domenico. 2014. "Novel Class of Potential Therapeutics that Target Ricin Retrograde Translocation." Toxins 6, no. 1: 33-53.


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