Elucidating pathway-selective biased CCKBR agonism for Alzheimer's disease treatment

Expressed in the entorhinal cortex (EC), the cholecystokinin (CCK) B receptor (CCKBR) plays an important role in memory and learning. Here, we identify that CCKBR-Gs and -Gq signaling, rather than CCKBR-Gi signaling, are beneficial for Alzheimer's disease (AD) treatment. Clinically, patients with more severe AD associated with lower CCKBR-Gq activity. The cryo-electron microscopy (cryo-EM) structures of CCKBR in complex with the endogenous agonist sulfated CCK8 (CCK8s) and 3 different G protein subtypes revealed that distinct receptor conformations contribute to selective G protein bias. Leveraging these structural insights, we rationally develop synthetic CCKBR agonists, including a Gi-biased agonist (z-44) and a Gq-biased agonist (3r1). Notably, 3r1 demonstrates therapeutic potential by ameliorating cognitive decline in 5×FAD mice, reducing the number of amyloid-β plaques, and promoting long-term potentiation (LTP) via upregulation of the α-secretase (ADAM10) and the calcium signaling molecule PLCB4. Our findings suggest that synthetic biased agonists targeting CCKBR-Gq signaling have therapeutic potential for AD.