Transcription factor YY1 is essential for regulation of the Th2 cytokine locus and for Th2 cell differentiation

Abstract

The Th2 locus control region (LCR) has been shown to be important in efficient and coordinated cytokine gene regulation during Th2 cell differentiation. However, the molecular mechanism for this is poorly understood. To study the molecular mechanism of the Th2 LCR, we searched for proteins binding to it. We discovered that transcription factor YY1 bound to the LCR and the entire Th2 cytokine locus in a Th2-specific manner. Retroviral overexpression of YY1 induced Th2 cytokine expression. CD4-specific knockdown of YY1 in mice caused marked reduction in Th2 cytokine expression, repressed chromatin remodeling, decreased intrachromosomal interactions, and resistance in an animal model of asthma. YY1 physically associated with GATA-binding protein-3 (GATA3) and is required for GATA3 binding to the locus. YY1 bound to the regulatory elements in the locus before GATA3 binding. Thus, YY1 cooperates with GATA3 and is required for regulation of the Th2 cytokine locus and Th2 cell differentiation. T h2 cytokine genes il4, il13, and il5 are clustered in chromosome 5 in human and chromosome 11 in mouse. The expression of the Th2 cytokine genes are coordinately regulated during Th2 cell differentiation. Several different regulatory elements have been shown to play an important role in Th2 cytokine gene expression, including promoters of Th2 cytokine genes, enhancers [conserved noncoding sequence 1 (CNS1)/hypersensitive site 1-3 (HSS1-3), hypersensitive site V (HSV)/CNS2, and intronic enhancer (IE)/ HSII], a silencer (HSIV), and a locus control region (LCR) (1, 2). The functions of these regulatory elements in Th2 cytokine expression in Th2 cells in vivo have been thoroughly investigated in transgenic mice and knockout mice that have targeted deletion in the regulatory elements (3-10). Among these regulatory elements, Th2 LCR has been shown to coordinately regulate Th2 cytokine genes, to induce chromatin remodeling, and to be required for chromosomal interactions (1, 2). The Th2 LCR is located in the introns of the Rad50 gene and is composed of four DNase I hypersensitive sites, including RHS4, RHS5, RHS6, and RHS7 (11,12). In previous studies, we have shown that the Th2 LCR is essential for Th2 cytokine expression and chromosome remodeling in the Th2 cytokine locus and in the pathogenesis of allergic asthma (7,11,13).The entire Th2 cytokine locus undergoes chromatin remodeling during Th2 cell differentiation (1, 2, 14). DNase I hypersensitive sites, which reflect accessibility of chromatin, are developed at the specific regulatory regions during Th2 cell differentiation (15, 16). Histone 3 lysine 9 (H3K9)-acetylation and histone 3 lysine 4 (H3K4)-methylation increase at specific regulatory regions in the Th2 cytokine locus during Th2 cell differentiation (17)(18)(19)(20). Th2 cytokine locus also undergoes DNA demethylation during Th2 cell differentiation (11,(21)(22)(23)(24)(25)(26). Treatment with drugs that cause chromatin modification such as 5-azacytidine or Trichostatin A induces Th2 cytokine expression upon T-cell recep...

Role of YY1 in long-range chromosomal interactions regulating Th2 cytokine expression

“…We also showed that YY1 does not compensate the loss of GATA3 in driving Th2 cytokine expression in Th1 cells. 4 These results support the idea that YY1's role in Th2 differentiation is that of organizing chromatin structure rather than direct transcriptional activation.…”

“…5 It has been shown to interact with many transcription factors, chromatin co-activators, and co-repressors. 5 In our previous study, we showed that knockdown of YY1 caused a reduction of intrachromosomal interactions between the Th2 LCR and the Il4 promoter, 4 suggesting that YY1 plays a role in this process. Long-range chromosomal interactions are important for regulation of gene transcription and genome maintenance.…”

“…In a recent study, we identified transcription factor Yin Yang 1 (YY1) as a Th2 LCRbinding protein, and we showed that YY1 plays an important role in gene expression, chromatin remodeling, and intrachromosomal interaction in the Th2 cytokine locus. 4 The roles of YY1 in these multiple events are discussed in detail, with particular focus on its role in chromosomal interactions.…”

T helper 2 (Th2) cell differentiation, type 2 innate lymphoid cell (ILC2) development and regulation of interleukin-4 (IL-4) and IL-13 production

“…Nfil3 (E4BP4), a transcription factor that is critical for the development of NK cells and ILCs 137–142 , is highly expressed by Th2 cells and responsible for regulating IL-10 production 143 . In addition, YY1 physically interacts with GATA3 and thus collaborates with GATA3 in chromatin remodeling and cytokine production 144 .…”

Review of Methods to Study Gene Expression Regulation Applied to Asthma

“…Using a TF-binding database and EMSA, YY1 was discovered as a candidate binding protein . The specifi c binding was confi rmed by antibody-supershift antibodies and oligonucleotide competition experiments [ 52 ].…”