Epigenetic silencing of V(D)J recombination is a major determinant for selective differentiation of mucosal-associated invariant t cells from induced pluripotent stem cells.

Yutaka Saito,Hiroshi Wakao,Chie Sugimoto,Toutai Mituyama,Toshi Shioda

doi:10.1371/journal.pone.0174699

Abstract

Mucosal-associated invariant T cells (MAITs) are innate-like T cells that play a pivotal role in the host defense against infectious diseases, and are also implicated in autoimmune diseases, metabolic diseases, and cancer. Recent studies have shown that induced pluripotent stem cells (iPSCs) derived from MAITs selectively redifferentiate into MAITs without altering their antigen specificity. Such a selective differentiation is a prerequisite for the use of MAITs in cell therapy and/or regenerative medicine. However, the molecular mechanisms underlying this phenomenon remain unclear. Here, we performed methylome and transcriptome analyses of MAITs during the course of differentiation from iPSCs. Our multi-omics analyses revealed that recombination-activating genes (RAG1 and RAG2) and DNA nucleotidylexotransferase (DNTT) were highly methylated with their expression being repressed throughout differentiation. Since these genes are essential for V(D)J recombination of the T cell receptor (TCR) locus, this indicates that nascent MAITs are kept from further rearrangement that may alter their antigen specificity. Importantly, we found that the repression of RAGs was assured in two layers: one by the modulation of transcription factors for RAGs, and the other by DNA methylation at the RAG loci. Together, our study provides a possible explanation for the unaltered antigen specificity in the selective differentiation of MAITs from iPSCs.

Highlights

The advent of induced pluripotent stem cells has enabled the generation of an unlimited number of desired cells upon differentiation for regenerative medicine and/or cell therapy
Wakao et al reported that invariant T cells, called mucosal-associated invariant T cells (MAITs), may be differentiated from induced pluripotent stem cells (iPSCs) in a highly selective manner without such external stimuli when iPSCs are prepared from MAITs (MAIT-iPSCs) [6]
In order to elucidate the molecular mechanisms underlying the selective differentiation of reMAITs from MAIT-iPSCs, we conducted transcriptome

Summary

Introduction

The advent of induced pluripotent stem cells (iPSCs) has enabled the generation of an unlimited number of desired cells upon differentiation for regenerative medicine and/or cell therapy. The first issue is intrinsic to the polyclonality of T cells generated from pluripotent cells because the repertoire of TCR is diverse and harbors no specificity to antigens. The second issue is that HSC- and/or ESC-derived T cells still possess the machinery relevant to DNA rearrangements, which may result in further rearrangements in TCR, thereby allowing TCR alternations. In this case, original antigen specificity will be lost, which is inconvenient for cell therapy. Wakao et al reported that invariant T cells, called mucosal-associated invariant T cells (MAITs), may be differentiated from iPSCs in a highly selective manner without such external stimuli when iPSCs are prepared from MAITs (MAIT-iPSCs) [6]

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Conclusion