Xin-Yue Zhou, Zhongyuan Xu, Xiwen Liu, Guiying Wu, Yudong Hou, Lian‐Wen Qi, Qun Liu, Jianbo Sun
Hepatic fibrosis is characterized by persistent hepatocyte injury and activation of hepatic stellate cells (HSCs), leading to excessive extracellular matrix deposition and impaired liver function. 5-hydroxytryptamine (5-HT) promotes HSCs activation and fibrogenesis via the 5-HT 2A receptor (5-HT 2A R, a GPCR). Herein, we developed novel bifunctional lysosome-targeting chimeras (LYTACs) by conjugating a potent 5-HT 2A R antagonist to a triantennary N-acetylgalactosamine (tri-GalNAc) ligand by using precisely optimized linkers. LY-res-3 induced potent, rapid, and selective degradation of endogenous 5-HT 2A R in asialoglycoprotein receptor (ASGPR)-positive hepatocytes. Mechanistic studies confirmed that LY-res-3 mediates inhibition of TGF-β release in hepatocytes, with this activity strictly dependent on ASGPR-mediated 5-HT 2A R endocytosis, followed by lysosomal degradation. Crucially, the bifunctional molecule concurrently maintained significant antagonism against 5-HT 2A R in activated HSCs, effectively blocking TGF-β downstream signaling. By combining targeted degradation with receptor antagonism, this strategy establishes a novel therapeutic modality targeting hepatocyte-HSCs crosstalk in liver fibrosis. Furthermore, it provides a powerful and generalizable method for developing hepatic-selective degraders against other challenging GPCRs implicated in liver fibrosis.