Two-Step Binding of Transcription Factors Causes Sequential Chromatin Structural Changes at the Activated IL-2 Promoter

Abstract

Most gene promoters have multiple binding sequences for many transcription factors, but the contribution of each of these factors to chromatin remodeling is still unclear. Although we previously found a dynamic change in the arrangement of nucleosome arrays at the Il2 promoter during T cell activation, its timing preceded that of a decrease in nucleosome occupancy at the promoter. Here we show that the initial nucleosome rearrangement was temporally correlated with the binding of NFAT1 and AP-1 (Fos/Jun), while the second step occurred in parallel with the recruitment of other transcription factors and RNA polymerase II. Pharmacologic inhibitors for activation of NFAT1 or induction of Fos blocked the initial phase in the sequential changes. This step was not affected, however, by inhibition of c-Jun phosphorylation, which instead blocked the binding of the late transcription factors, the recruitment of CREB-binding protein (CBP) and the acetylation of histone H3 at lysine 27 (H3K27ac). Thus, the sequential recruitment of transcription factors appears to facilitate two separate steps in chromatin remodeling at the Il2 locus.

Nuclear Factor of Activated T Cells 1 (NFAT1)-induced Permissive Chromatin Modification Facilitates Nuclear Factor-κB (NF-κB)-mediated Interleukin-9 (IL-9) Transactivation

“…A recent paper suggested a two-step process in the assembly of a transcription factor complex on the IL-2 promoter. NFAT1, Jun, and Fos are the early and Oct2, Rel A (p65), c-Rel, and NFAT2 are the late binding factors, respectively (75). Thus, sequential binding of transcription factors and coactivators are probably essential and general series of events for the TCR-induced IL-9 expression also.…”

Long-Range Transcriptional Control of the Il2 Gene by an Intergenic Enhancer

“…Stimulation through the TCR and CD28 is accompanied by posttranslational modification of histones and remodeling of a positioned nucleosome within the Il2 upstream regulatory region (10,20,29,30,33,34). This can be observed in recent DNase I hypersensitivity mapping data sets from the ENCODE project (18).…”

NFATc2 recruits cJun homodimers to an NFAT site to synergistically activate interleukin-2 transcription

“…After several hours of stimulation lower levels of IL-2 transcriptional activity are observed (Ishihara and Schwartz, 2011; Nguyen et al, 2010). Coincident with this, NFATc1 can be detected at the IL-2 promoter (Ishihara and Schwartz, 2011; Nguyen et al, 2010).…”

“…After several hours of stimulation lower levels of IL-2 transcriptional activity are observed (Ishihara and Schwartz, 2011; Nguyen et al, 2010). Coincident with this, NFATc1 can be detected at the IL-2 promoter (Ishihara and Schwartz, 2011; Nguyen et al, 2010). We have previously shown that NFATc1 is not capable of synergistically activating IL-2 transcription with cJun nor interacting with cJun homodimers off of DNA, which is consistent with the fact that NFATc1 lacks a C-terminal activation domain (Nguyen et al, 2010).…”

“…NFATc1 or NFATc2 bind cooperatively to DNA with dimers of the AP-1 family, comprised of Jun and Fos proteins (Chinenov and Kerppola, 2001; Ransone et al, 1989; Turner and Tjian, 1989). Specifically, cJun –which can homo- and heterodimerize – and cFos – which can only heterodimerize – function in IL-2 transcriptional activation (Ishihara and Schwartz, 2011; Nguyen et al, 2010). The IL-2 promoter spans from approximately −300 to +40 relative to the transcription start site (TSS) (Rooney et al, 1995).…”