A Highly Specific Monoacylglycerol Lipase PROTAC Probe

The key role of monoacylglycerol lipase (MAGL) in signaling pathways involving endocannabinoids and eicosanoids makes it a promising therapeutic target for numerous diseases, such as (neuro)inflammatory and neuropsychiatric disorders, along with acute tissue damage and cancer. From a mechanistic point of view, MAGL metabolizes the most common endocannabinoid, 2-arachidonylglycerol (2-AG), and additionally influences inflammatory signaling pathways by releasing arachidonic acid (AA). As of now, the therapeutic potential of MAGL has primarily been evaluated through the use of inhibitors and genetic knockout models. Herein, we describe the development of the first reversible MAGL proteolysis targeting chimeras (PROTACs). PROTAC degradation efficiency was dependent on the nature of the linker and E3-ligase system used. Cell permeability was proposed as a main limiting factor for their target engagement and degradation efficacy due to the excessive size and polarity of PROTAC conjugates. Molecular dynamics (MD) simulations revealed a chameleon-like behavior allowing the molecule to hide polar groups by forming intramolecular hydrogen bonds, showing environment-dependent lipophilicity. The best-performing reversible MAGL-PROTAC 4 is permeable, highly efficient with a DC50 < 1.0 nM, and specific in a relevant glioblastoma cell line, which was demonstrated by lipidomic and proteomic analysis. This PROTAC platform enables pharmacological silencing of both MAGLs’ catalytic and potentially elusive structural functions without impacting other proteins. We show that sole modulation of the endocannabinoid system via MAGL degradation using reversible PROTACs potently modulates the endocannabinoid 2-arachidonoyl (2-AG) and therefore holds great therapeutic potential.