Activity-Based Multimodal Probes Uncover the AChE-ADGRB Axis in Cellular and Murine Models of Depression

Acetylcholinesterase
(AChE) is a cholinergic enzyme that
hydrolyzes
the neurotransmitter acetylcholine (ACh). Dysregulated AChE activity
is closely linked to neurodegenerative diseases and cancer. Current
chemical probes for AChE detection mostly rely on single-modality
fluorescence readouts, limiting their utility. Herein, we developed
a set of activity-based multimodal probes, termed AFP1, AFP2, AFP3, and AFPP, which
combine the complementary strengths of near-infrared fluorescence
(NIRF) imaging, photoacoustic (PA) detection, and proteome profiling.
These probes offer a comprehensive toolset for deciphering the AChE
code in complex biological systems. AFP1/2/3 enable continuous monitoring of AChE activity via
NIRF/PA detection, while AFPP represents the first trimodal
probe for simultaneous NIRF/PA imaging and proteome profiling in live
systems. Notably, the usage of AFP2 and AFPP (1) highlighted the superior capability of PA imaging for deep-tissue
studies in live animals, (2) revealed significantly elevated AChE
activity in microglia compared to astrocytes in the depressive brain,
and (3) identified a functional link between AChE and adhesion G protein-coupled
receptor B2 and B3 (ADGRB2 and ADGRB3) in both cellular and murine
models of depression. Our study not only provides powerful molecular
tools for studying cholinergic systems but also reveals novel therapeutic
targets for depression intervention.