Antimuscarinic drugs exert beta-arrestin-biased agonism at the muscarinic acetylcholine type 1 receptor
Ontology highlight
ABSTRACT: Antimuscarinic drugs such as pirenzepine (PZ) and muscarinic toxin 7 (MT7), long considered M1 muscarinic acetylcholine receptor (M1R) antagonists, exhibit beta-arrestin-biased agonism. Using HEK293 cells and adult dorsal root ganglion (DRG) neurons, we show that PZ and MT7 selectively recruit beta-arrestin to M1R, activate ERK1/2 signaling, and promote neurite outgrowth without engaging G-alpha-q pathways or receptor internalization. Mass spectrometry identified six key M1R phosphorylation sites (T230, S251, T254, S321, T354, S356) required for beta-arrestin recruitment, with S251/T254 essential for PZ signaling. Casein kinase 2 (CK2), but not GRKs, mediates this phosphorylation; CK2 inhibition blocks beta-arrestin binding, ERK activation, and neurite outgrowth. These findings redefine antimuscarinic drugs as partial, beta-arrestin-biased M1R agonists and identify CK2 as a critical modulator of non-canonical M1R signaling relevant to sensory neuron regeneration and neuropathy therapy.
INSTRUMENT(S): Orbitrap Exploris 480
ORGANISM(S): Rattus Norvegicus (ncbitaxon:10116) Homo Sapiens (ncbitaxon:9606)
SUBMITTER:
Paul Fernyhough
PROVIDER: MSV000099707 | MassIVE | Fri Oct 31 09:35:00 GMT 2025
REPOSITORIES: MassIVE
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