The ETS Protein MEF Plays a Critical Role in Perforin Gene Expression and the Development of Natural Killer and NK-T Cells

NK cells play a central role in mediating innate immune responses. Activation of NK cells results in cytotoxicity, cytokine, and chemokine secretions. In this study, we show that in mice with targeted deletion of phospholipase Cγ (PLCγ)2, one of the key signal transducers, there are profound effects on the development and terminal maturation of NK cells. Lack of PLCγ2 significantly impaired the ability of lineage-committed NK precursor cells to acquire subset-specific Ly49 receptors and thereby terminal maturation of NK cells. Overexpression of isozyme, PLCγ1, in PLCγ2-deficient NK cells resulted in the successful Ly49 acquisition and terminal maturation of the NK cells; however, it could only partially rescue NKG2D-mediated cytotoxicity with no cytokine production. Furthermore, PLCγ2-deficient NK cells failed to mediate antitumor cytotoxicity and inflammatory cytokine production, displaying a generalized hyporesponsiveness. Our results strongly demonstrate that PLCγ1 and PLCγ2 play nonredundant and obligatory roles in NK cell ontogeny and in its effector functions.

Section: Discussionmentioning

confidence: 99%

Differential and Nonredundant Roles of Phospholipase Cγ2 and Phospholipase Cγ1 in the Terminal Maturation of NK Cells

Regunathan

Chen

Kutlesa

et al. 2006

“…Interestingly, this area is also adjacent to an Ets element (bp Ϫ497) that is involved in the expression of perforin in NK cells via the transcription factor MEF (22). The reason for the differential methylation patterns in CD4 ϩ and CD8 ϩ T cells is unclear, but the patterns must be under the control of regulatory domains that are not present in the analyzed DNA.…”

Section: Discussionmentioning

confidence: 99%

DNA Methylation and Chromatin Structure Regulate T Cell Perforin Gene Expression

Ray

et al. 2003

116

117

Perforin is a cytotoxic effector molecule expressed in NK cells and a subset of T cells. The mechanisms regulating its expression are incompletely understood. We observed that DNA methylation inhibition could increase perforin expression in T cells, so we examined the methylation pattern and chromatin structure of the human perforin promoter and upstream enhancer in primary CD4+ and CD8+ T cells as well as in an NK cell line that expresses perforin, compared with fibroblasts, which do not express perforin. The entire region was nearly completely unmethylated in the NK cell line and largely methylated in fibroblasts. In contrast, only the core promoter was constitutively unmethylated in primary CD4+ and CD8+ cells, and expression was associated with hypomethylation of an area residing between the upstream enhancer at −1 kb and the distal promoter at −0.3 kb. Treating T cells with the DNA methyltransferase inhibitor 5-azacytidine selectively demethylated this area and increased perforin expression. Selective methylation of this region suppressed promoter function in transfection assays. Finally, perforin expression and hypomethylation were associated with localized sensitivity of the 5′ flank to DNase I digestion, indicating an accessible configuration. These results indicate that DNA methylation and chromatin structure participate in the regulation of perforin expression in T cells.

“…During development in the thymus, the SLAM family of receptors, the adaptor protein SLAM-associated protein (SAP), and the Src family tyrosine kinase Fyn have all been implicated in a signaling axis required for selection of NKT cells (5,(17)(18)(19)(20). In addition, protein kinase C (PKC ), Vav-1, IFN-regulatory factor 1, ␥-ETS erythroblastosis virus E 26 oncogene homolog 1, E74-like factor 4 or myeloid ELF-1-like factor, runt-related transcription factor 1 (Runx1), and retinoic acid receptor-related orphan receptor-␥t (ROR␥t) have been shown to have significant roles in NKT cell development, function, and survival (21)(22)(23)(24)(25)(26)(27).…”

mentioning

confidence: 99%

The Tec Kinases Itk and Rlk Regulate NKT Cell Maturation, Cytokine Production, and Survival

Felices

Berg

2008

105

125

The Tec kinases Itk and Rlk are required for efficient positive selection of conventional CD4+ and CD8+ T cells in the thymus. In contrast, recent studies have shown that these Tec kinases are dispensable for the development of CD8+ T cells with characteristics of innate T cells. These findings raise questions about the potential role of Itk and Rlk in NKT cell development, because NKT cells represent a subset of innate T cells. To address this issue, we examined invariant NKT cells in Itk−/− and Itk/Rlk−/− mice. We find, as has been reported previously, that Itk−/− mice have reduced numbers of NKT cells with a predominantly immature phenotype. We further show that this defect is greatly exacerbated in the absence of both Itk and Rlk, leading to a 7-fold reduction in invariant NKT cell numbers in the thymus of Itk/Rlk−/− mice and a more severe block in NKT cell maturation. Splenic Itk−/− and Itk/Rlk−/− NKT cells are also functionally defective, because they produce little to no cytokine following in vivo activation. Tec kinase-deficient NKT cells also show enhanced cell death in the spleen. These defects correlate with greatly diminished expression of CD122, the IL-2R/IL-15R β-chain, and impaired expression of the T-box transcription factor, T-bet. These data indicate that the Tec kinases Itk and Rlk provide important signals for terminal maturation, efficient cytokine production, and peripheral survival of NKT cells.