Honig, Barry

Abstract Germinal center B-cell lymphomas frequently exhibit monoallelic loss-of-function mutations in the histone acetyltransferases CREBBP and p300, which contribute to lymphoma development, disrupt normal germinal center biology, and promote immune evasion. This study evaluates YF2, a histone acetyltransferase activator that increases CREBBP/p300 activity, as a potential therapeutic approach for B-cell lymphoma. YF2 binds the bromodomain of CREBBP/p300, increasing their auto-acetylation and enzymatic activity. It also induces cytotoxicity in B-cell lymphoma cell lines, with a stronger response in those carrying CREBBP / EP300 mutations. Additionally, YF2 increases the acetylation of key CREBBP/p300 substrates, including H3K27, p53, and BCL6, leading to enhanced apoptosis and altered B-cell diTerentiation. YF2 is well tolerated in vivo and extends survival in both cell line- and patient-derived xenograft mouse models. Moreover, YF2 exposure upregulates antigen-presentation markers and reshapes the immune microenvironment, strengthening responses to immune checkpoint blockade. Taken together, these findings support pharmacologic activation of CREBBP/p300 with YF2 as a compelling therapeutic strategy for B-cell lymphoma. Significance YF2 stimulates CREBBP/p300 activity to normalize B-cell diTerentiation and enhance immune recognition, oTering a potential approach to limit lymphoma progression and strengthen immunotherapy responses.

ABSTRACT Here, we show that cells expressing the adherens junction protein nectin-1 capture nectin-4-containing membranes from the surface of adjacent cells in a trans-endocytosis process. We find that internalized nectin-1–nectin-4 complexes follow the endocytic pathway. The nectin-1 cytoplasmic tail controls transfer: its deletion prevents trans-endocytosis, while its exchange with the nectin-4 tail reverses transfer direction. Nectin-1-expressing cells acquire dye-labeled cytoplasmic proteins synchronously with nectin-4, a process most active during cell adhesion. Some cytoplasmic cargo remains functional after transfer, as demonstrated with encapsidated genomes of measles virus (MeV). This virus uses nectin-4, but not nectin-1, as a receptor. Epithelial cells expressing nectin-4, but not those expressing another MeV receptor in its place, can transfer infection to nectin-1-expressing primary neurons. Thus, this newly discovered process can move cytoplasmic cargo, including infectious material, from epithelial cells to neurons. We name the process nectin-elicited cytoplasm transfer (NECT). NECT-related trans-endocytosis processes may be exploited by pathogens to extend tropism. This article has an associated First Person interview with the first author of the paper.