Transcription factor Bcl11b sustains iNKT1 and iNKT2 cell programs, restricts iNKT17 cell program, and governs iNKT cell survival

Abstract

Invariant natural killer T (iNKT) cells are innate-like T cells that recognize glycolipid antigens and play critical roles in regulation of immune responses. Based on expression of the transcription factors (TFs) Tbet, Plzf, and Rorγt, iNKT cells have been classified in effector subsets that emerge in the thymus, namely, iNKT1, iNKT2, and iNKT17. Deficiency in the TF Bcl11b in double-positive (DP) thymocytes has been shown to cause absence of iNKT cells in the thymus and periphery due to defective self glycolipid processing and presentation by DP thymocytes and undefined intrinsic alterations in iNKT precursors. We used a model of cre-mediated postselection deletion of Bcl11b in iNKT cells to determine its intrinsic role in these cells. We found that Bcl11b is expressed equivalently in all three effector iNKT subsets, and its removal caused a reduction in the numbers of iNKT1 and iNKT2 cells, but not in the numbers of iNKT17 cells. Additionally, we show that Bcl11b sustains subset-specific cytokine production by iNKT1 and iNKT2 cells and restricts expression of iNKT17 genes in iNKT1 and iNKT2 subsets, overall restraining the iNKT17 program in iNKT cells. The total numbers of iNKT cells were reduced in the absence of Bcl11b both in the thymus and periphery, associated with the decrease in iNKT1 and iNKT2 cell numbers and decrease in survival, related to changes in survival/apoptosis genes. Thus, these results extend our understanding of the role of Bcl11b in iNKT cells beyond their selection and demonstrate that Bcl11b is a key regulator of iNKT effector subsets, their function, identity, and survival.iNKT cell program | transcription factor Bcl11b | iNKT1 effector cells | iNKT2 effector cells | iNKT17 effector cells

TET proteins regulate the lineage specification and TCR-mediated expansion of iNKT cells

“…3c). Genes that were downregulated in Tet2-Tet3 DKO stage 0 i NKT precursors relative to their expression in wild-type cells included those encoding CD4, Bcl11b (which restricts the NKT17 lineage 23 ) and Satb1 (which forms complexes with PLZF in the presence of the Cullin E3 ligase 24 ); genes that were upregulated included Zbtb16 (which encodes PLZF) and Lmo4 (Fig. 3c).…”

The differentiation of ROR-γt expressing iNKT17 cells is orchestrated by Runx1

“…6b ). The transcription factors Bcl11b and Lef1 restrain the differentiation of iNKT17 cells as iNKT cells deficient for either transcription factor had increased frequencies of ROR-γt expressing iNKT17 cells 27 , 29 . Interestingly, in PLZF-cre Runx1 cKO mice, there was a statistically significant increased expression of both Bcl11b (2 fold) and Lef1 (2 fold) in Stage 2 iNKT cells (Fig.…”

“…While BATF, c-Maf and NKAP positively regulate iNKT17 differentiation; the transcription factors Bcl11b and Lef1 restrain iNKT17 differentiation. Deficiency in either factor in iNKT cells led to an increased frequency of iNKT17 cells 27 , 29 . Although, Runx1 can induce rorc expression and associate with ROR-γt during Th17 differentiation 39 , its role in iNKT17 differentiation has not been defined.…”

“…The transcriptional repressor NKAP is also required for iNKT cell proliferation and differentiation of ROR-γt expressing iNKT17 cells 26 . The transcription factor Bcl11b is important for restraining the NKT17 differentiation program to allow for differentiation of iNKT2 and iNKT1 cells 27 . The transcription factor Lef1 is also important for iNKT cell proliferation and is crucial for differentiation of iNKT2 cells 28 , 29 .…”

NKT cells and the regulation of intestinal immunity: a two‐way street

“…For instance, in support of thymic commitment it has been shown that the TCR signal strength during thymic development can direct the differentiation of iNKT cells within specific functional subsets . Further to this, a variety of signalling molecules and transcription factors including Zap70, Bcl11b or Roquin has been shown to participate in the control of iNKT cell lineage differentiation . On the other hand, several lines of evidence suggest that iNKT cells can acquire functional capabilities in the periphery.…”