Pharmacological modulation of cannabinoid type 2 receptor (CB2R) holds promise for the treatment of numerous conditions, including inflammatory diseases, autoimmune disorders, pain, and cancer. Despite the significance of this receptor, researchers lack reliable tools to address questions concerning the expression and complex mechanism of CB2R signaling, especially in cell-type and tissue-dependent context. Herein, we report for the first time a versatile ligand platform for the modular design of a collection of highly specific CB2R fluorescent probes, used successfully across applications, species and cell types. These include flow cytometry of endogenously expressing cells, real-time confocal microscopy of mouse splenocytes and human macrophages, as well as FRET-based kinetic and equilibrium binding assays. High CB2R specificity was demonstrated by competition experiments in living cells expressing CB2R at native levels. The probes were effectively applied to FACS analysis of microglial cells derived from a mouse model relevant to Alzheimer's disease and to the detection of CB2R in human breast cancer cells.

Herein we report the development of a turn‐on lanthanide luminescent probe for time‐gated detection of nitroreductases (NTRs) in live bacteria. The probe is activated through NTR‐induced formation of the sensitizing carbostyril antenna and resulting energy transfer to the lanthanide center. This novel NTR‐responsive trigger is virtually non‐fluorescent in its inactivated form and features a large signal increase upon activation. We show that the probe is capable of selectively sensing NTR in lysates as well as in live bacteria of the ESKAPE family which are clinically highly relevant multiresistant pathogens responsible for the majority of hospital infections. The results suggest that our probe could be used to develop diagnostic tools for bacterial infections.

Despite its essential role in the (patho)physiology of several diseases, CB2R tissue expression profiles and signaling mechanisms are not yet fully understood. We report the development of a highly potent,...

Cannabinoid type 2 receptor (CB2R) is a fundamental part of the endocannabinoid signaling system (eCB system), and is known to play an important role in tissue injury, inflammation, cancer and pain. In stark contrast to its significance, the underlying signaling mechanisms and tissue expression profiles are poorly understood. Due to its low expression in healthy tissue and lack of reliable chemical tools, CB2R visualization in live cells remains uncharted. Here we report the development of a drug derived toolbox of highly potent, CB2Rselective fluorescent probes based on reverse design. Extensive validation in several applications such as CB2R detection in flow cytometry and time-resolved imaging, and the development of a novel fluorescent-based TR-FRET assay to generate kinetic and equilibrium binding data demonstrate the high versatility of our toolbox. These probes are the first to preserve affinity and efficacy in both human and mouse CB2R, a crucial aspect for preclinical translatability, and to enable imaging of CB2R internalization in living cells using confocal microscopy.

Cannabinoid type 2 receptor (CB2R) is a fundamental part of the endocannabinoid signaling system (eCB system), and is known to play an important role in tissue injury, inflammation, cancer and pain. In stark contrast to its significance, the underlying signaling mechanisms and tissue expression profiles are poorly understood. Due to its low expression in healthy tissue and lack of reliable chemical tools, CB2R visualization in live cells remains uncharted. Here we report the development of a drug derived toolbox of highly potent, CB2Rselective fluorescent probes based on reverse design. Extensive validation in several applications such as CB2R detection in flow cytometry and time-resolved imaging, and the development of a novel fluorescent-based TR-FRET assay to generate kinetic and equilibrium binding data demonstrate the high versatility of our toolbox. These probes are the first to preserve affinity and efficacy in both human and mouse CB2R, a crucial aspect for preclinical translatability, and to enable imaging of CB2R internalization in living cells using confocal microscopy.