Protein-protein interaction antagonists as novel inhibitors of non-canonical polyubiquitylation

[Background]: Several pathways that control cell survival under stress, namely RNF8-dependent DNA damage recognition and repair, PCNA-dependent DNA damage tolerance and activation of NF-kB by extrinsic signals, are regulated by the tagging of key proteins with lysine 63-based polyubiquitylated chains, catalyzed by the conserved ubiquitin conjugating heterodimeric enzyme Ubc13-Uev. [Methodology/Principal Findings]: By applying a selection based on in vivo protein-protein interaction assays of compounds from a combinatorial chemical library followed by virtual screening, we have developed small molecules that efficiently antagonize the Ubc13-Uev1 protein-protein interaction, inhibiting the enzymatic activity of the heterodimer. In mammalian cells, they inhibit lysine 63-type polyubiquitylation of PCNA, inhibit activation of NF-kB by TNF-a and sensitize tumor cells to chemotherapeutic agents. One of these compounds significantly inhibited invasiveness, clonogenicity and tumor growth of prostate cancer cells. [Conclusions/Significance]: This is the first development of pharmacological inhibitors of non-canonical polyubiquitylation that show that these compounds produce selective biological effects with potential therapeutic applications.This work was funded by grants from the Consejo Superior de Investigaciones Cientificas (PIF200580 to T.M.T., A.R.O. and A. Messeguer), the Ministerio de Educacion y Ciencia (SAF2005-05109-CO2-01 to T.M.T.; CTQ2005-00995 and GEN2003-20642-C09-09 to A. Messeguer; BIO2005-0576, and GEN2003-206420-C09-08 to A.R.O.), the Comunidad de Madrid (GR/SAL/0306/2004 and 200520M157 to A.R.O.), and an institutional grant from the Fundacion Ramon Areces. J.S. and M.G.R. are receipients of fellowships from the Ministerio de Educacion y Ciencia, and A. Moure of a I3P fellowship from the Consejo Superior de Investigaciones Cientificas.Peer reviewe

Protein-protein interaction antagonists as novel inhibitors of non-canonical polyubiquitylation.

BACKGROUND: Several pathways that control cell survival under stress, namely RNF8-dependent DNA damage recognition and repair, PCNA-dependent DNA damage tolerance and activation of NF-kappaB by extrinsic signals, are regulated by the tagging of key proteins with lysine 63-based polyubiquitylated chains, catalyzed by the conserved ubiquitin conjugating heterodimeric enzyme Ubc13-Uev. METHODOLOGY/PRINCIPAL FINDINGS: By applying a selection based on in vivo protein-protein interaction assays of compounds from a combinatorial chemical library followed by virtual screening, we have developed small molecules that efficiently antagonize the Ubc13-Uev1 protein-protein interaction, inhibiting the enzymatic activity of the heterodimer. In mammalian cells, they inhibit lysine 63-type polyubiquitylation of PCNA, inhibit activation of NF-kappaB by TNF-alpha and sensitize tumor cells to chemotherapeutic agents. One of these compounds significantly inhibited invasiveness, clonogenicity and tumor growth of prostate cancer cells. CONCLUSIONS/SIGNIFICANCE: This is the first development of pharmacological inhibitors of non-canonical polyubiquitylation that show that these compounds produce selective biological effects with potential therapeutic applications