Multiple layers of transcriptional regulation by PLZF in NKT-cell development

Abstract

The transcription factor PLZF [promyelocytic leukemia zinc finger, encoded by zinc finger BTB domain containing 16 (Zbtb16)] is induced during the development of innate and innate-like lymphocytes to direct their acquisition of a T-helper effector program, but the molecular mechanisms involved are poorly understood. Using biotinylationbased ChIP-seq and microarray analysis of both natural killer T (NKT) cells and PLZF-transgenic thymocytes, we identified several layers of regulation of the innate-like NKT effector program. First, PLZF bound and regulated genes encoding cytokine receptors as well as homing and adhesion receptors; second, PLZF bound and activated T-helperspecific transcription factor genes that in turn control T-helper-specific programs; finally, PLZF bound and suppressed the transcription of Bach2, a potent general repressor of effector differentiation in naive T cells. These findings reveal the multilayered architecture of the transcriptional program recruited by PLZF and elucidate how a single transcription factor can drive the developmental acquisition of a broad effector program.atural killer (NK) T (NKT) cells are a conserved population of innate-like T cells that express CD1d-restricted semi-invariant αβ T-cell receptors (TCRs), using mostly the Vα14-Jα18 chain in mouse (Vα24-Jα18 in human) combined with variable Vβ8, Vβ7, and Vβ2 (Vβ11 in human) chains, which confer recognition of conserved self and foreign lipids (1-3). NKT cell precursors arise during thymic development at the CD4 + CD8+ double-positive stage and undergo massive expansion on interaction with CD1d ligands expressed on cortical thymocytes. They also characteristically acquire an effector CD44 hi CD62L lo phenotype along with receptors of the NK cell lineage. The innate-like effector functions of NKT cells are illustrated by the cells' ability to promptly secrete large quantities of both IL-4 and IFN-γ either after TCR activation or on exposure to tissue-and antigen-presenting cell-derived cytokines, such as IL-25+IL-33 and IL-12+IL-18, respectively. Whereas C57BL/6 mice produce predominantly NKT cells with a T-bet-dependent type 1 helper phenotype (NKT1), other strains, including BALB/c, also express substantial populations of so-called NKT2 and NKT17 cells with polarized type 2 and type 17 helper programs controlled by GATA3 and RORγt, respectively.The BTB-zinc finger transcription factor PLZF (promyelocytic leukemia zinc finger, encoded by Zbtb16), is specifically expressed in NKT cells, but not in conventional T cells or NK cells, and directs the acquisition of several key components of the NKT cell effector program during development, including cytokine and migration properties (4-7). Mutations or deletion of Zbtb16 abrogate both the expansion and the effector-memory differentiation of NKT cells, resulting in reversal to a naive phenotype and redistribution to the lymph nodes and circulating blood. PLZF expression is also essential for the development of other innate-like T cells, including MR1-specific semi-invariant ...

The histone demethylase UTX regulates the lineage-specific epigenetic program of invariant natural killer T cells

“…By utilizing a PLZF ChIP-Seq data set that defined PLZF-activated genes in i NKT cells 39 , we determined that loss of UTX in i NKT cells leads to impaired activation of PLZF target gene expression (Fig. 7a).…”

Using CRISPR/Cas9 engineering to generate a mouse with a conditional knockout allele for the promyelocytic leukemia zinc finger transcription factor

“…Positioned within the C‐terminal region of PLZF, the nine C2H2 zinc finger motifs facilitate direct sequence‐specific DNA binding to target genes. Cell and signaling context dependent, PLZF can serve as a transcriptional activator or repressor (Fahnenstich et al, ; Gaber, Butler, & Novitch, ; Ikeda et al, ; Kommagani et al, ; Labbaye et al, ; Liu et al, ; Mao et al, ; Singh et al, ; Suliman et al, ; Szwarc et al, ; Wang et al, ). Given its pleiotropic effects, PLZF drives a broad spectrum of developmental processes and physiological responses, including limb skeletal patterning, innate immune cell development, hematopoiesis, and spermatogenesis; reviewed in Suliman et al ().…”

The peripheral differentiation of human natural killer T cells

“…The development of murine NKT cells is thought to comprise four stages, based on the expression of CD24, CD44 and NK1.1 . Further nuances are suggested by the existence of mature PLZF high Tbet low RORγt low interleukin (IL)‐4‐producing and PLZF high Tbet low RORγt high IL‐17‐producing subsets in the thymus that resemble NK1.1 − NKT cells . It is also likely that peripheral CD4 + and CD4 − NKT cells in mice represent distinct lineages that emigrate independently from the thymus .…”

“…9,10 Further nuances are suggested by the existence of mature PLZF high Tbet low RORct low interleukin (IL)-4-producing and PLZF high Tbet low RORct high IL-17-producing subsets in the thymus that resemble NK1.1 À NKT cells. 11,12 It is also likely that peripheral CD4 + and CD4 À NKT cells in mice represent distinct lineages that emigrate independently from the thymus. 13 However, the extent to which human NKT cells follow an equivalent differentiation pathway remains unclear, despite close parallels in the TCR-mediated antigen recognition process and the highly conserved nature of CD1d.…”