Biology subjects

den Haan, J. M.

Publications and source records attributed to den Haan, J. M..

3 recordsLinked to original sources

bioRxiv2025

Histone methyltransferase DOT1L differentially affects the development of dendritic cell subsets

Dendritic cells (DCs) are important orchestrators of immune responses. Their development in the bone marrow is controlled by transcription factors, but epigenetic mechanisms remain poorly understood. DOT1L is emerging as a key epigenetic regulator in immune cells. By mapping DOT1L-mediated histone H3K79 methylation in canonical DC subsets, we observed that DOT1L modified common as well as DC subset-specific genes. In vitro- or in vivo-induced deletion of Dot1l followed by in vitro cell culture resulted in a decrease in myeloid progenitors and plasmacytoid DCs (pDCs) and an increase in cDC2s, while cDC1s remained unchanged. In vitro generated Dot1l-KO DCs were unable to produce IFN upon stimulation. Moreover, transcriptomes of Dot1l-KO DC subsets exhibited enrichment of antigen presentation pathways and MHC class II surface levels were upregulated in pDCs. Mechanistically, inhibition of DOT1L linked the observed effects to its methyltransferase activity. Together, our data indicate that in DCs DOT1L differentially affects the development of canonical subsets and suppresses antigen presentation pathways.

cell biology↗

bioRxiv2025

B cells maintain the homeostasis of splenic marginal zone antigen-presenting cells to promote the anti-viral CD8+ T cell response

Natural killer and CD8+ T cells are critical in the elimination of blood-borne viruses such as cytomegalovirus (CMV); however, the role of B cells in this process is less clear. Here, using the murine CMV (MCMV) infection model, we demonstrated that the B cell-deficient mice mounted a weaker primary virus-specific CD8+ T cell response than their wild-type counterparts, which was associated with increased viral transcription. Notably, we found that the contribution of B cells to the CD8+ T-cell-mediated anti-viral response was not associated with their ability to generate antibodies but with their ability to sustain Langerin+ type 1 conventional dendritic cells (cDC1s), a dendritic cells (DC) subset known for being involved in viral and bacterial clearance in the marginal zone of the spleen. Furthermore, we found that the presence of Langerin+ cDC1s is dependent on B cells expressing lymphotoxin (LT{beta}) to maintain CD169+ marginal metallophilic macrophages (MMMs). We further discovered, using ligand-receptor interaction analyses, that the communication between MMMs and Langerin+ cDC1s was mediated via VCAM1 - ITGA4/ITGB1 interaction. Thus, our data reveals that B cell regulate the development of MMMs in the spleen via LT{beta} expression and consequently sustain Langerin+ cDC1s homeostasis for effective initiation of an anti-viral CD8+ T cell response. Overall, our study offers a new perspective on how B cells maintain the homeostasis of antigen-presenting cells in the splenic marginal zone and thus indirectly affect the virus-specific CD8+ T cell response, which could potentially be extended to other infectious and autoimmune diseases as well as tumors.

immunology↗

bioRxiv2019

The histone methyltransferase DOT1L prevents antigen-independent differentiation and safeguards epigenetic identity of CD8+ T cells

Cytotoxic T-cell differentiation is guided by epigenome adaptations but how epigenetic mechanisms control lymphocyte development has not been well defined. Here we show that the histone methyltransferase DOT1L, which marks the nucleosome core on active genes, safeguards normal differentiation of CD8+ T cells. T-cell specific ablation of Dot1L resulted in loss of naive CD8+ T cells and premature differentiation towards a memory-like state, independent of antigen exposure and in a cell-intrinsic manner. Without DOT1L, the memory-like CD8+ cells fail to acquire full effector functions in vitro and in vivo. Mechanistically, DOT1L controlled T-cell differentiation and function by ensuring normal T-cell receptor density and signaling, and by maintaining epigenetic identity, in part by indirectly supporting the repression of developmentally-regulated genes. Through our study DOT1L is emerging as a central player in physiology of CD8+ T cells, acting as a barrier to prevent premature differentiation and supporting the licensing of the full effector potential of cytotoxic T cells.

immunology↗