Tcf1 Sustains the Expression of Multiple Regulators in Promoting Early Natural Killer Cell Development.

Juanjuan Liu,Shanshan Hao,Xiaohan Ma,Yajiao Zhang,Wenhui Guo,Feng Chen,Jingjing Liu,Yanyi Zhao,Shunzong Yuan,Fang Wang,Youmin Kang,Yingpeng Yao,Guotao Yu,Shuyang Yu,Zhao Wang

doi:10.3389/fimmu.2021.791220

Abstract

T cell factor 1 (Tcf1) is known as a critical mediator for natural killer (NK) cell development and terminal maturation. However, its essential targets and precise mechanisms involved in early NK progenitors (NKP) are not well clarified. To investigate the role of Tcf1 in NK cells at distinct developmental phases, we employed three kinds of genetic mouse models, namely, Tcf7 fl/fl Vav Cre/+, Tcf7 fl/fl CD122 Cre/+ and Tcf7 fl/fl Ncr1 Cre/+ mice, respectively. Similar to Tcf1 germline knockout mice, we found notably diminished cell number and defective development in BM NK cells from all strains. In contrast, Tcf7 fl/fl Ncr1 Cre/+ mice exhibited modest defects in splenic NK cells compared with those in the other two strains. By analyzing the published ATAC-seq and ChIP-seq data, we found that Tcf1 directly targeted 110 NK cell-related genes which displayed differential accessibility in the absence of Tcf1. Along with this clue, we further confirmed that a series of essential regulators were expressed aberrantly in distinct BM NK subsets with conditional ablating Tcf1 at NKP stage. Eomes, Ets1, Gata3, Ikzf1, Ikzf2, Nfil3, Runx3, Sh2d1a, Slamf6, Tbx21, Tox, and Zeb2 were downregulated, whereas Spi1 and Gzmb were upregulated in distinct NK subsets due to Tcf1 deficiency. The dysregulation of these genes jointly caused severe defects in NK cells lacking Tcf1. Thus, our study identified essential targets of Tcf1 in NK cells, providing new insights into Tcf1-dependent regulatory programs in step-wise governing NK cell development.

Highlights

Natural killer (NK) cells are one of the founding members of the innate lymphoid cell (ILC) family [1], which play essential roles in primary immune response via their cytotoxicity or cytokine production activities without prior sensitization [2]
To gain insights of the importance of Tcf1 in the entire process of NK cell development, we went over the expression of Tcf7 from hematopoietic stem cells (HSC) to distinct NK cell subsets along with developmental phases by analyzing published data (GSE109125) from the ImmGen database
Compared with other classic NK regulators, Tcf7 exhibits dynamic expression and upregulates its expression beyond common lymphoid progenitor (CLP) stage (Figure 1A). We found it reached a peak in CD11blow (CD3e−NK1.1+CD27+CD11b−) iNK compartment in both bone marrow (BM) and spleen (SP) at a relatively high level in comparison with housekeeping gene expression of Gapdh or Hprt1 (Figure 1A)

Summary

Introduction

Natural killer (NK) cells are one of the founding members of the innate lymphoid cell (ILC) family [1], which play essential roles in primary immune response via their cytotoxicity or cytokine production activities without prior sensitization [2]. The upregulation of CD122, b-chain of the IL-15 receptor, is associated with the commitment to the NK cell lineage [5, 6], thereof the NK cell progenitors (NKPs) can be generally defined by expressing CD122 with the activating receptor NKG2D within lineage negative population of bone marrow (BM) [7]. This NKP population has been further identified by the co-expression of 2B4 (CD244), CD27 (Tnfrsf7), and surface lymphocyte activation molecule (SLAM)-family receptors with the majority of these cells expressing IL-7Ra [8]. Accompanying with the dynamic expression of CD27 and CD11b, the NK1.1+ or NCR1+ murine NK cells can be further subdivided into three developmental phases, namely, immature NK (iNK, CD27+CD11b−) stage, transitional double positive (DP, CD27+CD11b+) stage, and terminal mature NK (mNK, CD27−CD11b+) stage [9], which express high level of KLRG1 [10]

Methods

Results

Conclusion