The long non-coding RNA Dreg1 is required for optimal ILC2 development

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    eLife Assessment

    This is a useful study that investigates the role of the long non-coding RNA Dreg1 for the development, differentiation, or maintenance of group 2 ILC (ILC2). The authors generate Dreg1-/- mice and show a reduction of group 2 innate lymphoid cells (ILC2). However, the strength of evidence supporting the impact of Dreg1 on Gata3 expression, a transcription factor required for ILC2 cell fate decisions, and the cell-intrinsic requirement of Dreg1 for ILC2 remain incomplete. This study will be of interest to immunologists.

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Abstract

Gata3 is an essential transcription factor for the development of several distinct immune cell lineages such as T cells, natural killer (NK) cells and innate lymphoid cells (ILC). As such, the levels and timing of Gata3 expression are critical for directing lineage fate decisions. The Gata3 locus has a complex and dynamic distal regulatory enhancer landscape. Recently we identified a non-coding RNA, Dreg1, located immediately upstream of the classic +280kb T/NK cell enhancer (Tce1). To test its function, we excised the Dreg1 locus in mice and observed a selective reduction of group 2 ILCs (ILC2) across multiple tissues, but mature T, NK and other ILC lineages remained unchanged. In bone marrow, common innate lymphoid cell progenitors (ILCP) increased while ILC2 progenitors (ILC2P) decreased, with a modest reduction of Gata3 in upstream progenitors consistent with an early developmental bottleneck. Chromatin profiling showed the Dreg1 locus is accessible in early lymphoid progenitors and became decorated with H3K27ac in ILCP in a Tcf1-dependent manner. Furthermore, Tcf1-deficient cells did not express Dreg1 and showed alterations in the epigenetic landscape of the Dreg1 locus. Finally, we discovered that potential homologues of Dreg1 harboured in a syntenic enhancer of GATA3 are also highly expressed in human ILC2. Taken together we conclude that Dreg1 is a Tcf1-dependent non-coding RNA critical for fine tuning the high level of Gata3 required for the optimal development of the ILC2 lineage.

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  1. eLife Assessment

    This is a useful study that investigates the role of the long non-coding RNA Dreg1 for the development, differentiation, or maintenance of group 2 ILC (ILC2). The authors generate Dreg1-/- mice and show a reduction of group 2 innate lymphoid cells (ILC2). However, the strength of evidence supporting the impact of Dreg1 on Gata3 expression, a transcription factor required for ILC2 cell fate decisions, and the cell-intrinsic requirement of Dreg1 for ILC2 remain incomplete. This study will be of interest to immunologists.

  2. Reviewer #1 (Public review):

    Summary:

    This study examines the role of the long non-coding RNA Dreg1 in regulating Gata3 expression and ILC2 development. Using Dreg1-deficient mice, the authors show a selective loss of ILC2s but not T or NK cells, suggesting a lineage-specific requirement for Dreg1. By integrating public chromatin and TF-binding datasets, they propose a Tcf1-Dreg1-Gata3 regulatory axis. The topic is relevant for understanding epigenetic regulation of ILC differentiation.

    Strengths:

    (1) Clear in vivo evidence for a lineage-specific role of Dreg1.

    (2) Comprehensive integration of genomic datasets.

    (3) Cross-species comparison linking mouse and human regulatory regions.

    Weaknesses:

    (1) Mechanistic conclusions remain correlative, relying on public data.

    (2) Lack of direct chromatin or transcriptional validation of Tcf1-mediated regulation.

    (3) Human enhancer function is not experimentally confirmed.

    (4) Insufficient methodological detail and limited mechanistic discussion.

  3. Reviewer #2 (Public review):

    The authors investigate the role of the long non-coding RNA Dreg1 for the development, differentiation, or maintenance of group 2 ILC (ILC2). Dreg1 is encoded close to the Gata3 locus, a transcription factor implicated in the differentiation of T cells and ILC, and in particular of type 2 immune cells (i.e., Th2 cells and ILC2). The center of the paper is the generation of a Dreg1-deficient mouse. While Dreg1-/- mice did not show any profound ab T or gd T cell, ILC1, ILC3, and NK cell phenotypes, ILC2 frequencies were reduced in various organs tested (small intestine, lung, visceral adipose tissue). In the bone marrow, immature ILC2 or ILC2 progenitors were reduced, whereas a common ILC progenitor was overrepresented, suggesting a differentiation block. Using ATAC-seq, the authors find that the promoter of Dreg1 is open in early lymphoid progenitors, and the acquisition of chromatin accessibility downstream correlates with increased Dreg1 expression in ILC2 progenitors. Examining publicly available Tcf1 CUT&Run data, they find that Tcf1 was specifically bound to the accessible sites of the Dreg1 locus in early innate lymphoid progenitors. Finally, the syntenic region in the human genome contains two non-coding RNA genes with an expression pattern resembling mouse Dreg1.

    The topic of the manuscript is interesting. However, there are various limitations that are summarized below.

    (1) The authors generated a new mouse model. The strategy should be better described, including the genetic background of the initially microinjected material. How many generations was the targeted offspring backcrossed to C57BL/6J?

    (2) The data is obtained from mice in which the Dreg1 gene is deleted in all cells. A cell-intrinsic role of Dreg1 in ILC2 has not been demonstrated. It should be shown that Dreg1 is required in ILC2 and their progenitors.

    (3) The data on how Dreg1 contributes to the differentiation and or maintenance of ILC2 is not addressed at a very definitive level. Does Dreg1 affect Gata3 expression, mRNA stability, or turnover in ILC2? Previous work of the authors indicated that knockdown of Dreg1 does not affect Gata3 expression (PMID: 32970351).

    (4) How Dreg1 exactly affects ILC2 differentiation remains unclear.