Involvement of PU.1 in the transcriptional regulation of TNF-α
Involvement of PU.1 in the transcriptional regulation of TNF-α
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DOI：
10.1016/j.bbrc.2009.07.126
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发表时间：
2009-10-09
影响因子：
3.1
通讯作者：
Okumura, Ko
中科院分区：
文献类型：
--
作者：
Fukai, Tatsuo;Nishiyama, Chiharu;Okumura, Ko
PU.1是一种骨髓和淋巴特异性转录因子，在造血谱系的发育和特异性基因调控中发挥许多重要作用。肥大细胞（MC）和树突状细胞（DC）分别以低水平和高水平表达PU. 1。以前，我们发现，在MC中PU.1的强制表达导致获得DC样特征，包括由于IgE信号传导相关分子的表达减少而抑制几种IgE介导的反应。相比之下，MC中的PU.1过表达响应于IgE和LPS刺激而上调TNF-α的产生，这表明PU.1正调节TNF-α的表达。然而，PU.1在TNF-α表达中的作用在很大程度上是未知的。在本研究中，研究了PU.1对小鼠骨髓来源（BM）MC和DC中TNF-α启动子的影响。实时PCR、ELISA和染色质免疫沉淀分析表明，LPS或IgE刺激后TNF-α表达水平的动力学和幅度与PU.1与启动子结合的量有关。简而言之，在DC中观察到TNF-α启动子功能的较高和延迟的上调，而在MC中有较低和快速的反应。当PU.1过表达逆转录病毒载体被引入MC中时，募集到TNF-α启动子的PU.1的量显著增加。通过siRNA敲低BMDC中的PU.1导致由LPS刺激的BMDC产生的TNF-α蛋白减少。这些观察结果表明，PU.1反式激活TNF-α启动子，并且结合在启动子上的PU.1的量与启动子活性相关。(C)2009 Elsevier Inc. All rights reserved.
PU.1 is a myeloid-and lymphoid-specific transcription factor that serves many important roles in the development and specific gene regulation of hematopoietic lineages. Mast cells (MC) and dendritic cells (DC) express PU.1 at low and high levels, respectively. Previously, we found that enforced expression of PU.1 in MC resulted in acquisition of DC-like characteristics, including repression of several IgE-mediated responses due to reduced expression of IgE-signaling related molecules. In contrast, PU.1 overexpression in MC up-regulated TNF-alpha production in response to IgE- and LPS-stimulation suggesting that PU.1 positively regulates TNF-alpha expression. However, the role of PU.1 in the expression of TNF-alpha is largely unknown. In the present study, the effects of PU.1 on the TNF-alpha promoter in mouse bone marrow-derived (BM) MC and DC were studied. Real-time PCR, ELISA, and chromatin immunoprecipitation assays indicated that the kinetics and magnitude of TNF-alpha expression levels following LPS- or IgE-stimulation are related to the amount of PU.1 binding to the promoter. In brief, higher and delayed up-regulation of TNF-alpha promoter function was observed in DC, whereas there were lower and rapid responses in MC. When PU.1-overexpressing retrovirus vector was introduced into MC, the amount of PU.1 recruited to the TNF-alpha promoter markedly increased. The knockdown of PU.1 in BMDC by siRNA resulted in a reduction of TNF-alpha protein produced from LPS-stimulated BMDC. These observations indicate that PU.1 transactivates the TNF-alpha promoter and that the amount of PU.1 binding on the promoter is associated with promoter activity. (C) 2009 Elsevier Inc. All rights reserved.