Discovery and Mechanism of Action of Small Molecule Inhibitors of Ceramidases**
Robert D. Healey, Essa M. Saied, Xiaojing Cong, Gergely Karsai, Ludovic Gabellier, Julie Saint‐Paul, Elise Del Nero, Sylvain Jeannot, Marion Drapeau, Simon Fontanel, Damien Maurel, Shibom Basu, Cédric Leyrat, Jérôme Golebiowski, Guillaume Bossis, Chérine Bechara, Thorsten Hornemann, Christoph Arenz, Sébastien Granier
Abstract
Sphingolipid metabolism is tightly controlled by enzymes to regulate essential processes in human physiology. The central metabolite is ceramide, a pro-apoptotic lipid catabolized by ceramidase enzymes to produce pro-proliferative sphingosine-1-phosphate. Alkaline ceramidases are transmembrane enzymes that recently attracted attention for drug development in fatty liver diseases. However, due to their hydrophobic nature, no specific small molecule inhibitors have been reported. We present the discovery and mechanism of action of the first drug-like inhibitors of alkaline ceramidase 3 (ACER3). In particular, we chemically engineered novel fluorescent ceramide substrates enabling screening of large compound libraries and characterized enzyme:inhibitor interactions using mass spectrometry and MD simulations. In addition to revealing a new paradigm for inhibition of lipid metabolising enzymes with non-lipidic small molecules, our data lay the ground for targeting ACER3 in drug discovery efforts.