Cryo-EM structures of human GPR34 enable the identification of selective antagonists.

GPR34 is a functional G-protein-coupled receptor of Lysophosphatidylserine (LysoPS), and has pathogenic roles in numerous diseases, yet remains poorly targeted. We herein report a cryo-electron microscopy (cryo-EM) structure of GPR34 bound with LysoPS (18:1) and Gi protein, revealing a unique ligand recognition mode with the negatively charged head group of LysoPS occupying a polar cavity formed by TM3, 6 and 7, and the hydrophobic tail of LysoPS residing in a lateral open hydrophobic groove formed by TM3-5. Virtual screening and subsequent structural optimization led to the identification of a highly potent and selective antagonist (YL-365). Design of fusion proteins allowed successful determination of the challenging cryo-EM structure of the inactive GPR34 complexed with YL-365, which revealed the competitive binding of YL-365 in a portion of the orthosteric binding pocket of GPR34 and the antagonist-binding-induced allostery in the receptor, implicating the inhibition mechanism of YL-365. Moreover, YL-365 displayed excellent activity in a neuropathic pain model without obvious toxicity. Collectively, this study offers mechanistic insights into the endogenous agonist recognition and antagonist inhibition of GPR34, and provides proof of concept that targeting GPR34 represents a promising strategy for disease treatment.

Myeloid PTEN promotes chemotherapy-induced NLRP3-inflammasome activation and antitumour immunity.

PTEN is a dual-specificity phosphatase that is frequently mutated in human cancer, and its deficiency in cancer has been associated with therapy resistance and poor survival. Although the intrinsic tumour-suppressor function of PTEN has been well established, evidence of its role in the tumour immune microenvironment is lacking. Here, we show that chemotherapy-induced antitumour immune responses and tumour suppression rely on myeloid-cell PTEN, which is essential for chemotherapy-induced activation of the NLRP3 inflammasome and antitumour immunity. PTEN directly interacts with and dephosphorylates NLRP3 to enable NLRP3-ASC interaction, inflammasome assembly and activation. Importantly, supplementation of IL-1ß restores chemotherapy sensitivity in mouse myeloid cells with a PTEN deficiency. Clinically, chemotherapy-induced IL-1ß production and antitumour immunity in patients with cancer is correlated with PTEN expression in myeloid cells, but not tumour cells. Our results demonstrate that myeloid PTEN can determine chemotherapy responsiveness by promoting NLRP3-dependent antitumour immunity and suggest that myeloid PTEN might be a potential biomarker to predict chemotherapy responses.