Germinal centers (GCs) are important sites for antibody diversification and affinity maturation and are also a common origin of B-cell malignancies. Although made up of motile cells, GCs are tightly confined within B-cell follicles. The cues promoting GC B-cell confinement are incompletely understood. P2RY8 is a Gα13-coupled receptor that mediates migration inhibition and growth regulation of B cells in lymphoid tissues 4 , 6 . P2RY8 is frequently mutated in GC-derived diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL) 1 – 5 , and the ligand for this receptor has been undefined. In a search for P2RY8 ligands, we found P2RY8 bioactivity in bile and in culture supernatants of several cell lines. Using a seven-step biochemical fractionation procedure and a drop-out mass spectrometry approach, we identified a previously undescribed biomolecule, S-geranylgeranyl-L-glutathione (Ggg) as a potent P2RY8 ligand. Ggg was detectable in lymphoid tissues in the nanomolar range. Ggg inhibited chemokine-mediated migration of human GC B cells and follicular helper T cells and antagonized induction of pAkt in GC B cells. We found that gamma-glutamyltransferase-5 (Ggt5) metabolized Ggg to a form inactive on the receptor. Ggt5 was highly expressed by follicular dendritic cells (FDCs). Over-expression of this enzyme disrupted the ability of P2RY8 to promote B-cell confinement to GCs, indicating that it establishes a Ggg gradient in lymphoid tissues. This work defines Ggg as an intercellular signaling molecule involved in organizing and controlling GC responses. As well as DLBCL and BL the P2RY8 locus is modified in several other cancers and we speculate that Ggg has organizing and growth regulatory activities in multiple human tissues.
Prolonged drug residence times may result in longer-lasting drug efficacy, improved pharmacodynamic properties, and "kinetic selectivity" over off-targets with high drug dissociation rates. However, few strategies have been elaborated to rationally modulate drug residence time and thereby to integrate this key property into the drug development process. Herein, we show that the interaction between a halogen moiety on an inhibitor and an aromatic residue in the target protein can significantly increase inhibitor residence time. By using the interaction of the serine/threonine kinase haspin with 5-iodotubercidin (5-iTU) derivatives as a model for an archetypal active-state (type I) kinase-inhibitor binding mode, we demonstrate that inhibitor residence times markedly increase with the size and polarizability of the halogen atom. The halogen-aromatic π interactions in the haspin-inhibitor complexes were characterized by means of kinetic, thermodynamic, and structural measurements along with binding-energy calculations.
The mixed lineage kinase ZAK is a key regulator of the MAPK pathway mediating cell survival and inflammatory response. ZAK is targeted by several clinically approved kinase inhibitors, and inhibition of ZAK has been reported to protect from doxorubicin-induced cardiomyopathy. On the other hand, unintended targeting of ZAK has been linked to severe adverse effects such as the development of cutaneous squamous cell carcinoma. Therefore, both specific inhibitors of ZAK, as well as anticancer drugs lacking off-target activity against ZAK, may provide therapeutic benefit. Here we report the first crystal structure of ZAK in complex with the B-RAF inhibitor vemurafenib. The co-crystal structure displayed a number of ZAK-specific features including a highly distorted P loop conformation enabling rational inhibitor design. Positional scanning peptide library analysis revealed a unique substrate specificity of the ZAK kinase including unprecedented preferences for histidine residues at positions −1 and +2 relative to the phosphoacceptor site. In addition, we screened a library of clinical kinase inhibitors identifying several inhibitors that potently inhibit ZAK, demonstrating that this kinase is commonly mistargeted by currently used anticancer drugs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.