The methyltransferase DOT1L limits activation and the Th1 program in CD4⁺T cells during infection and inflammation

Abstract

1 SUMMARY Histone methyltransferases comprise a major class of epigenetic enzymes that are emerging as important regulators of Th cell biology. Here, Scheer et al. report that DOT1L is a key regulator of the Th cell lineage and integrity, thereby affecting Th cell-dependent responses at mucosal sites. ABSTRACT CD4 + T helper (Th) cell differentiation is controlled by lineage-specific expression of transcription factors and effector proteins, as well as silencing of lineage-promiscuous genes. Lysine methyltransferases (KMTs) comprise a major class of epigenetic enzymes that are emerging as important regulators of Th cell biology. Here, we show that the KMT DOT1L regulates Th cell function and lineage integrity. DOT1L-dependent dimethylation of lysine 79 of histone H3 (H3K79me2) is associated with lineage-specific gene expression. However, DOT1L-deficient Th cells overproduce IFN-γ under lineage-specific and lineage-promiscuous conditions. Consistent with the increased IFN-γ response, mice with a T cell-specific deletion of DOT1L are susceptible to infection with the helminth parasite Trichuris muris and resistant to the development of allergic lung inflammation. These results identify a central role for DOT1L in Th cell lineage commitment and stability, and suggest that inhibition of DOT1L may provide a novel therapeutic strategy to limit type 2 immune responses.

Divergent cytokine and transcriptional signatures control functional T follicular helper cell heterogeneity

“…The majority of Tfh cells demonstrated cytokine specialization, with minimal cells producing IFN, IL-4, or IL-17 in combination (Figure 1I). Intracellular cytokine expression was confirmed using IFN-GFPx4C13R reporter mice for T. muris infection which, in addition to similar IFN and IL-4 expression, indicated the presence of an IL-13-expressing Tfh population (Figure S3C) 63 . Serum cytokine analysis largely reflected that observed in draining lymph nodes, with additional expression of TNF seen in each infection, suggesting that Tfh cytokine production reflects the overall infection milieu (Figure S3D).…”

“…Mice were bred and maintained on a C57BL/6 background under specific pathogenfree conditions. T-bet-ZsGreen reporter 61 , IL-4-AmCyan-IL-13-DsRed-IFN-γ-GFP reporter 8,63 Human tonsil samples Cryopreserved tonsil samples were obtained from three healthy adults (30-38 yearsold; 1 female, 2 male). All procedures involving human participants were approved by and in accordance with the ethical standards of Human Research Ethics Committee at WEHI and the 1964 Helsinki Declaration and its later amendments.…”

DOT1L inhibition does not modify the sensitivity of cutaneous T cell lymphoma to pan-HDAC inhibitors in vitro

“…Inhibition of DOT1L during in vitro mouse T cell culture alleviates the T cell receptor stimulation threshold, thereby attenuating graft-versus-host-disease in allogeneic T cell transplantation (Kagoya et al, 2018). Furthermore, DOT1L is essential for normal CD4 + and CD8 + T cell development and differentiation in mice (Bian et al, 2020;Kwesi-Maliepaard et al, 2020;Scheer et al, 2020;Wille and Sridharan, 2022). The role of HDACs in CD4 + T cells has been studied extensively.…”

“…Inhibition of HDACs in human CD4 + T cells induces regulatory T cell differentiation and affects cytokine expression (Ellmeier and Seiser, 2018). Given the important roles of HDAC and DOT1L in lymphocytes (Haery et al, 2015;Ellmeier and Seiser, 2018;Kealy et al, 2020;Kwesi-Maliepaard et al, 2020;Scheer et al, 2020;Aslam et al, 2021;Wille and Sridharan, 2022) it would certainly be interesting the assess the effect of HDAC inhibitors in combination with DOT1L inhibitors on normal immune cells and in other types of lymphoma. Taken together, although we could not find synergistic or suppressive effects of HDAC-and DOT1Linhibitors in CTCL during short term in vitro cell culture, the crosstalk between HDAC and DOT1L still warrants further investigation, especially in the context of in vivo immune responses.…”