Physical and Functional Analysis of the Putative Rpn13 Inhibitor RA190.

Abstract

Rpn13 is one of several ubiquitin receptors in the 26S proteasome. Cys88 of Rpn13 has been proposed to be the principal target of RA190, an electrophilic small molecule with interesting anti-cancer activities. Here, we examine the claim that RA190 mediates its cytotoxic effects through engagement with Rpn13. We find no evidence that this is the case. In vitro, RA190 is has no measurable effect on any of the known interactions of Rpn13. In cellulo, we see no physical engagement of Rpn13 by RA190, either on C88 or any other residue. However, chemical proteomics experiments in two different cell lines reveal that dozens of other proteins are heavily engaged by RA190. Finally, increasing or reducing the level of Rpn13 in HeLa and melanoma cells had no effect on the sensitivity of HeLa or melanoma cells to RA190. We conclude that Rpn13 is not the physiologically relevant target of RA190.

• Authors: Paige Dickson, Daniel Abegg, Ekaterina Vinogradova, Junichiro Takaya, Hongchan An, Scott Simanski, Benjamin F Cravatt, Alexander Adibekian, Thomas Kodadek
• Journal: Cell chemical biology (Cell Chem Biol) Vol. 27 Issue 11 Pg. 1371-1382.e6 (11 19 2020) ISSN: 2451-9448 [Electronic] United States
• PMID: 32857985 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2020 Elsevier Ltd. All rights reserved.

Chemical References

• ADRM1 protein, human
• Benzylidene Compounds
• Intracellular Signaling Peptides and Proteins
• RA190

Topics

• Benzylidene Compounds (chemical synthesis, chemistry, pharmacology)
• Cells, Cultured
• Female
• Humans
• Intracellular Signaling Peptides and Proteins (antagonists & inhibitors, genetics, metabolism)
• Molecular Structure