PU.1 Suppresses Th2 Cytokine Expression via Silencing of GATA3 Transcription in Dendritic Cells.
PU.1 Suppresses Th2 Cytokine Expression via Silencing of GATA3 Transcription in Dendritic Cells.
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DOI：
10.1371/journal.pone.0137699
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Nishiyama C
中科院分区：
文献类型：
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作者：
Yashiro T;Kubo M;Ogawa H;Okumura K;Nishiyama C
转录因子PU.1主要在树突状细胞(DC)中表达，是DC分化所必需的。虽然有几个报道表明PU1正向调节DC特异性基因的表达，但PU1是否也对DC具有抑制作用在很大程度上尚不清楚。在这里，我们证明PU.1通过抑制Th2分化的主要调节因子GATA3的表达来抑制包括IL-13和IL-5在内的Th2细胞因子在骨髓来源的DC(BMDCs)中的表达。当将PU.1 siRNA导入BMDCs后，内毒素诱导的IL-13和IL-5的表达增加，GATA2和GATA3的组成性表达上调。另外，GATA3 siRNA而不是GATA2 siRNA的引入取消了PU.1 siRNA介导的IL-13和IL-5的上调。染色质免疫沉淀分析表明，PU1结合在GATA3近端启动子区域，在驱动DC转录GATA3方面比远端启动子更具优势。在PU.1 siRNA导入的DC中，GATA3启动子上的组蛋白乙酰化程度降低，提示PU.1参与了GATA3启动子的染色质修饰。用组蛋白脱乙酰酶(HDAC)抑制剂曲古抑素A处理后，组蛋白H3在GATA3启动子上的乙酰化程度增加，并诱导随后的GATA3表达。使用HDAC抑制剂和siRNAs的实验表明，HDAC3抑制GATA3的表达。通过PU1基因敲除，HDAC3在GATA3启动子上的募集减少。在缺乏保守的GATA3反应元件CGRE的小鼠产生的BMDCs中，内毒素诱导的IL-13表达显著减少，CGRE是GATA3与IL-13启动子结合的关键部位。在PU.1 siRNA转染的刺激DC中，CGRE处H3K4me3的表达程度显著增加。我们的结果表明，PU1在DC的发育和功能中起着关键作用，它不仅是转录激活因子，也是抑制因子。
The transcription factor PU.1 is predominantly expressed in dendritic cells (DCs) and is essential for DC differentiation. Although there are several reports that PU.1 positively regulates the expression of DC-specific genes, whether PU.1 also has a suppressive effect on DCs is largely unknown. Here we demonstrate that PU.1 suppresses the expression of Th2 cytokines including IL-13 and IL-5 in bone marrow-derived DCs (BMDCs), through repression of the expression of GATA3, which is a master regulator of Th2 differentiations. When PU.1 siRNA was introduced into BMDCs, LPS-induced expression of IL-13 and IL-5 was increased along with upregulation of the constitutive expression of GATA2 and GATA3. The additional introduction of GATA3 siRNA but not of GATA2 siRNA abrogated PU.1 siRNA-mediated upregulation of IL-13 and IL-5. A chromatin immunoprecipitation assay showed that PU.1 bound to Gata3 proximal promoter region, which is more dominant than the distal promoter in driving GATA3 transcription in DCs. The degree of histone acetylation at the Gata3 promoter was decreased in PU.1 siRNA-introduced DCs, suggesting the involvement of PU.1 in chromatin modification of the Gata3 promoter. Treatment with a histone deacetylase (HDAC) inhibitor, trichostatin A, increased the degree of histone H3 acetylation at the Gata3 promoter and induced the subsequent expression of GATA3. Experiments using HDAC inhibitors and siRNAs showed that HDAC3 suppressed GATA3 expression. The recruitment of HDAC3 to the Gata3 promoter was decreased by PU.1 knockdown. LPS-induced IL-13 expression was dramatically reduced in BMDCs generated from mice lacking the conserved GATA3 response element, termed CGRE, which is an essential site for the binding of GATA3 on the Il-13 promoter. The degree of H3K4me3 at CGRE was significantly increased in PU.1 siRNA-transfected stimulated DCs. Our results indicate that PU.1 plays pivotal roles in DC development and function, serving not only as a transcriptional activator but also as a repressor.