Novel Class of Potential Therapeutics that Target Ricin Retrograde Translocation

Toxins

Veronika Redmann²  Thomas Gardner²  Zerlina Lau¹  Keita Morohashi¹  Dan Felsenfeld¹ 

[1]Icahn School of Medicine at Mount Sinai, Integrated Screening Core, Experimental Therapeutics Institute, One Gustave L. Levy Place, New York, NY 10029, USA

[2] E-Mails:

[3]IcahnSchool of Medicine at Mount Sinai, Department of Microbiology, One Gustave L. Levy Place, New York, NY 10029, USA

[4]E-Mails:

关键词: ricin toxin;    small molecule inhibitors;    high-content screen;    retrograde translocation;    stabilization;    dislocation;    egfp;    ribosome-inactivating protein;   

DOI  :  10.3390/toxins6010033

来源: mdpi

【 摘 要 】

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 (RTA_E177Qegfp) to identify compounds that target RTA retrograde translocation. Stabilizing RTA_E177Qegfp 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.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.