Tumor necrosis factor (TNF) is one of the key primary response genes in the immuneKeywords: Chromatin conformation r Th cells r T lymphocyte r TNF r Transcription start site Additional supporting information may be found in the online version of this article at the publisher's web-site
IntroductionTumor necrosis factor (TNF) is a pleiotropic cytokine expressed by various types of lymphoid and myeloid cells, including T cells, B cells, NK cells, monocytes, macrophages, DCs, and mast cells (reviewed in [1,2]). TNF is involved in development, homeostasis, and activation of the immune system [3][4][5][6][7][8]. Physiological functions mediated by TNF depend on the cellular sources and the molecular form of this cytokine [9][10][11]. In particular, TNF produced by macrophages and T cells plays different roles in immune and inflammatory reactions [9,10]. TNF is the primary response gene in macrophages where it has a permissive chromatin conformation [12,13]. Even without stimulation, the proximal TNF Correspondence: Dr. Yury V. Shebzukhov e-mail: shebzukhov@drfz.de promoter and transcription start site (TSS) have an open chromatin configuration in primary monocytes and macrophages and in the majority of tested myelomonocytic cell lines [14][15][16][17][18][19][20][21][22]. Various T-cell subsets produce different amounts of TNF in correlation with their pathophysiological potential [23]. Earlier studies [24] as well as recent advances in high-throughput analysis of DNaseI chromatin accessibility indicate that the proximal part of the TNF promoter in T cells is open (Supporting Information Fig. 1); however, in contrast to macrophages, the TSS of TNF in T cells acquires open chromatin conformation only after activation or polarization under Th1 or Th17 (where Th is T helper) conditions. TNF gene expression in T cells is regulated by the NFAT and AP-1 families of transcription factors; in particular, activation of the proximal TNF promoter region involves functional interactions with the transcription factors NFATc2 and c-Jun [25][26][27][28][29][30][31]. Numerous reports also supported the involvement of the NF-κB family members in transcriptional regulation of the TNF gene inwww.eji-journal.eu
252Yury V. Shebzukhov et al. Eur. J. Immunol. 2014. 44: 251-264 macrophages, in spite of the lack of canonical high-affinity NF-κB binding sites within the proximal TNF promoter [32][33][34][35][36][37][38][39]. However, specific role of NF-κB family members in regulation of the TNF gene is still being debated ([1, 2] and Discussion section). In murine T cells, members of the NF-κB family were shown to bind to the distal part of the TNF promoter [40] and to the enhancer element immediately downstream of the TNF gene (3 -TNF enhancer) [24], but the functional significance of these interactions is not clear.Here, we demonstrate the difference in chromatin structure around TNF TSS between T cells and macrophages. We further show that active forms of c-Jun and NFATc2 transcription factors are involved in chromatin remodeling oc...
