Small Molecule Inhibition of the Autophagy Kinase ULK1 and Identification of ULK1 Substrates

Many tumors become addicted to autophagy for survival, suggesting inhibition of autophagy as a potential broadly applicable cancer therapy. ULK1/Atg1 is the only serine/threonine kinase in the core autophagy pathway and thus represents an excellent drug target. Despite recent advances in the underst...

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Bibliographic Details
Published in:Molecular cell 2015-07, Vol.59 (2), p.285-297
Main Authors: Egan, Daniel F., Chun, Matthew G.H., Vamos, Mitchell, Zou, Haixia, Rong, Juan, Miller, Chad J., Lou, Hua Jane, Raveendra-Panickar, Dhanya, Yang, Chih-Cheng, Sheffler, Douglas J., Teriete, Peter, Asara, John M., Turk, Benjamin E., Cosford, Nicholas D.P., Shaw, Reuben J.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Autophagy - drug effects
Autophagy - physiology
Autophagy-Related Protein-1 Homolog
Benzamides - chemistry
Benzamides - pharmacology
Catalytic Domain - genetics
Cell Survival - drug effects
Cell Survival - physiology
Cells, Cultured
Consensus Sequence
Gene Knockout Techniques
HEK293 Cells
Humans
Intracellular Signaling Peptides and Proteins - antagonists & inhibitors
Intracellular Signaling Peptides and Proteins - genetics
Intracellular Signaling Peptides and Proteins - metabolism
Mice
Molecular Sequence Data
Phosphorylation
Protein Kinase Inhibitors - chemistry
Protein Kinase Inhibitors - pharmacology
Protein-Serine-Threonine Kinases - antagonists & inhibitors
Protein-Serine-Threonine Kinases - deficiency
Protein-Serine-Threonine Kinases - genetics
Protein-Serine-Threonine Kinases - metabolism
Pyrimidines - chemistry
Pyrimidines - pharmacology
Recombinant Proteins - chemistry
Recombinant Proteins - genetics
Recombinant Proteins - metabolism
RNA, Small Interfering - genetics
Substrate Specificity
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Summary:Many tumors become addicted to autophagy for survival, suggesting inhibition of autophagy as a potential broadly applicable cancer therapy. ULK1/Atg1 is the only serine/threonine kinase in the core autophagy pathway and thus represents an excellent drug target. Despite recent advances in the understanding of ULK1 activation by nutrient deprivation, how ULK1 promotes autophagy remains poorly understood. Here, we screened degenerate peptide libraries to deduce the optimal ULK1 substrate motif and discovered 15 phosphorylation sites in core autophagy proteins that were verified as in vivo ULK1 targets. We utilized these ULK1 substrates to perform a cell-based screen to identify and characterize a potent ULK1 small molecule inhibitor. The compound SBI-0206965 is a highly selective ULK1 kinase inhibitor in vitro and suppressed ULK1-mediated phosphorylation events in cells, regulating autophagy and cell survival. SBI-0206965 greatly synergized with mechanistic target of rapamycin (mTOR) inhibitors to kill tumor cells, providing a strong rationale for their combined use in the clinic. [Display omitted] •ULK1 phosphorylates multiple autophagy components, including VPS34 on Ser249•SBI-0206965 is a highly selective ULK1 kinase inhibitor that blocks autophagy•SBI-0206965 combined with starvation or mTOR inhibition leads to ULK1 degradation•SBI-0206965 synergizes with mTOR inhibition to induce cell death ULK1 is a serine/threonine kinase that initiates autophagy in response to nutrient deprivation. Egan et al. define ULK1’s consensus phosphorylation motif, demonstrate that ULK1 phosphorylates several autophagy components, and develop a ULK1 small molecule inhibitor (SBI-0206965). SBI-0206965 synergizes with mTOR inhibition to enhance apoptosis in tumor cells, suggesting therapeutic opportunities.
ISSN:1097-2765
1097-4164
DOI:10.1016/j.molcel.2015.05.031