The transcription factor Fli1 restricts the formation of memory precursor NK cells during viral infection

Abstract

Natural killer (NK) cells are innate lymphocytes that possess traits of adaptive immunity, such as memory formation. However, the molecular mechanisms by which NK cells persist to form memory cells are not well understood. Using single cell RNA sequencing, we identified two distinct effector NK cell (NK eff ) populations following mouse cytomegalovirus (MCMV) infection. Ly6C – memory precursor (MP) NK cells displayed enhanced survival during the contraction phase in a Bcl2-dependent manner, and differentiated into Ly6C + memory NK cells. MP NK cells exhibited distinct transcriptional and epigenetic signatures compared to Ly6C + NK eff cells, with a core epigenetic signature shared with MP CD8 + T cells enriched in ETS1 and Fli1 DNA-binding motifs. Fli1 was induced by STAT5 signaling ex vivo, and increased levels of the pro-apoptotic factor Bim in early effector NK cells following viral infection. These results suggest that a NK cell-intrinsic checkpoint controlled by the transcription factor Fli1 limits MP NK formation by regulating early effector NK cell fitness during viral infection.

Sex differences in NK cells mediated by the X-linked epigenetic regulator UTX

“…Splenic single cell suspensions were lysed in red blood cell lysis buffer and resuspended in EasySep™ buffer (Stemcell). To avoid depleting Ly6C + NK cells we developed a custom antibody cocktail as follows: splenocytes were labeled with 10 μg per spleen of biotin conjugated antibodies against CD3 (17A2), CD19 (6D5), CD8 (53-6.7), CD88 (20/70), Ly6G (1A8), SiglecF (S17007L), TCRβ (H57-597), CD20 (SA275A11), CD172a (P84) and magnetically depleted from total splenocyte suspensions with the use of anti-biotin coupled magnetic beads (Biolegend) 58 .…”

The X-linked epigenetic regulator UTX controls NK cell-intrinsic sex differences

“…3h-k). Moreover, regulation of NK cell apoptosis and survival relies on the relative expression levels of Bcl-2 (anti-apoptotic factor) 30 , which can be antagonized by Bim (pro-apoptotic factor) 31 . UTX NKD NK cells showed increased intracellular protein expression of Bcl-2 and a modest increase in Bim (Fig.…”

“…Noteworthy genes involved in NK cell homeostasis (Bcl2 and Thy1; Fig. 6f) 30,42 and effector function (Ifng and Csf2) were UTX bound, differentially accessible and differentially expressed (Fig. 6g).…”

“…Splenic single-cell suspensions were lysed in red blood cell lysis buffer and resuspended in EasySep buffer (StemCell). To avoid depleting Ly6C + NK cells, we developed a custom antibody cocktail as follows: splenocytes were labeled with 10 μg per spleen of biotin-conjugated antibodies against CD3 (17A2), CD19 (6D5), CD8 (53-6.7), CD88 (20/70), Ly6G (1A8), SiglecF (S17007L), TCRβ (H57-597), CD20 (SA275A11), CD172a (P84) and magnetically depleted from total splenocyte suspensions with the use of anti-biotin-coupled magnetic beads (BioLegend) 30 .…”

Transcriptional Activation of Regenerative Hematopoiesis via Vascular Niche Sensing

“…Global embryonic Fli-1 deficiency results in fetal lethality attributed to vascular leakiness, and adult hematopoietic inducible Fli-1 genetic deletion impairs development and maturation of some hematopoietic myeloid lineages, affecting also the numbers of and skewing between myeloid progenitors 22, 23 , and directs megakaryocyte cell fate specification 24 . Additionally, Fli-1 regulates lymphocyte progeny by restricting formation of memory NK cells 25 and by restraining effector T cell lineage differentiation 26 . Nonetheless, the physiological role of the Fli-1 TF in modulating active versus quiescent states of adult immune stem cells was never defined.…”