Abstract
Cell-specific regulation of endogenous G protein-coupled receptors (GPCRs) is crucial for understanding their roles in physiological processes. We present chemogenetic tools using shield-1-dependent irreversible protein switches to regulate peptide agonist activity. To demonstrate this platform, we engineered chemogenetically regulated pituitary adenylate cyclase activating polypeptide (cPACAP), which exhibited >15-fold chemical-dependent regulation of endogenous receptor activity. In vivo application of cPACAP allowed neuronal activation via the endogenous receptor for PACAP, engaging neural circuits that control respiratory and feeding behaviors. By integrating cPACAP with transgenic mice, we selectively activated endogenous PACAP receptor signaling in hypocretin-expressing neurons of the lateral hypothalamic area (LHA), revealing its role in regulating sighing, a stress-related physiological output. We further extended this design to chemogenetically regulate the parathyroid hormone receptor and corticotropin-releasing factor peptide receptor activity. Using a common small molecule, these chemogenetic tools enable temporally regulated peptidergic activation of endogenous GPCRs in targeted cell populations, facilitating the study of their function.