Abstract
AbstractChemical proteomics is widely applied in small‐molecule target identification. However, in general it does not identify non‐protein small‐molecule targets, and thus, alternative methods for target identification are in high demand. We report the discovery of the autophagy inhibitor autoquin and the identification of its molecular mode of action using image‐based morphological profiling in the cell painting assay. A compound‐induced fingerprint representing changes in 579 cellular parameters revealed that autoquin accumulates in lysosomes and inhibits their fusion with autophagosomes. In addition, autoquin sequesters Fe2+ in lysosomes, resulting in an increase of lysosomal reactive oxygen species and ultimately cell death. Such a mechanism of action would have been challenging to unravel by current methods. This work demonstrates the potential of the cell painting assay to deconvolute modes of action of small molecules, warranting wider application in chemical biology.
Highlights
The identification of small molecules to probe biological systems is at the heart of chemical biology
In general it does not identify non-protein small-molecule targets, and alternative methods for target identification are in high demand
We report the discovery of the autophagy inhibitor autoquin and the identification of its molecular mode of action using imagebased morphological profiling in the cell painting assay
Summary
The identification of small molecules to probe biological systems is at the heart of chemical biology. Analysis of morphological changes induced by core was required for autophagy inhibitory activity To this end, the four major cinchona alkaloids quinidine, quinine, cinchonine, and cinchonidine were subjected to Borono–Minisci conditions[17] to selectively functionalise the C2 position and to evaluate the importance of the relative stereochemistry at the quinuclidine ring (Scheme 1 b). C) Synthesis of C3functionalised derivatives using selective CÀH activation followed by Suzuki similar potency in the autophagy assay, suggesting that the oxazatwistane ring was not essential for biological activity (Table 1, Entry 1). This compound, which we named autoquin, provided a benchmark against which all other compounds coupling. Cinchonine derivatives, lacking the C6 methoxy group (Entries 12–21), were all less
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