Role of Aryl hydrocarbon receptor (AhR) and RelB during the initiation of dendrit

描述(申请人提供)：本研究旨在探讨树突状细胞(DC)分化过程中转录因子芳烃受体(AhR)和核因子？B成员RelB之间的串扰新机制。该项目的长期目标是深入了解AhR的内源性作用及其与RelB一起调控基因转录，特别是细胞因子和趋化因子等免疫调节基因的作用的缺失知识。最近的研究发现，作为核因子-βB家族的一员，RelB可能在经典的AhR信号通路中发挥重要作用，这为本研究提供了主要的推动力。在本研究中，我们将评估人DC体外系统中AhR/RelB活性与DC分化过程的生理学相关性。我们喜欢评价已建立的人髓系细胞系U937和THP-1作为DC样细胞的来源，因为大多数(如果不是全部)DC和二恶英的研究都是在小鼠或小鼠来源的细胞中进行的。此外，我们希望通过流式细胞仪检测CD1a、CD40、CD80、CD86和MHCII等活化标志物和实时定量PCR分析与DC功能相关的趋化因子DC-CK1、DC-STAMP和IL-8mRNA的表达，来检测TCDD(AhR激动剂)和AhR拮抗剂对DC分化和生物学反应的影响。在本提案的项目2中，我们将确定AhR和AhR/RelB活性在C57BL/6野生型和AhR缺失(AhR-/-)小鼠骨髓细胞向DC分化过程中的作用。这项研究揭示了AhR和RelB功能的新概念，对于理解二恶英等环境毒物如何影响免疫系统和人类健康的关键功能至关重要。与公共卫生相关：大约15年前，Hankinson和他的同事发现了编码蛋白Arnt，它是芳香烃受体(AhR)依赖于配体的移位到细胞核以及与二恶英反应元件(DRE)结合所必需的，介导了异源代谢酶的诱导(经典的AhR/Arnt途径)，但AhR的生理作用仍然是一个关键问题。本研究重点探讨了AhR与核因子-βB亚基通路RelB(Alternative AhR/RelB通路)之间的一种新的串扰机制，揭示了激活的AhR通路如何与核因子-βB亚单位RelB连接，从而协同调节细胞因子/趋化因子的表达以及树突状细胞的分化和功能。这项工作将有助于了解环境毒物如二恶英或二恶英类化合物是如何激活AhR，引起免疫毒性效应并导致不良健康影响的机制。

DESCRIPTION (provided by applicant): This proposal investigates a new mechanism of cross talk between the transcription factors Aryl hydrocarbon Receptor (AhR) and the NF-?B member RelB in the process of dendritic cell (DC) differentiation. The long-term objective of the project is to give insight into the missing knowledge about the endogenous role of the AhR and its role together with RelB in regulating gene transcription especially immune regulatory genes like cytokines and chemokines. The major impetus for this study has been provided by recent findings that RelB, a member of the NF-?B family, may play an important role in the classical AhR signaling pathway. In the present study, we will assess the physiological relevance of the AhR/RelB activity in human DC in vitro systems for the process of DC differentiation. We like to evaluate the established human myeloid cell lines U937 and THP-1 as a source of DC-like cells since most if not all studies with DC and dioxin have been performed in mice or cells derived from mouse. Further, we like to test the effect of TCDD (AhR agonist) and AhR antagonists on differentiation and the biological response of the DCs based on the measurement of selected activation markers such as surface expression of CD1a, CD40, CD80, CD86 and MHCII by flow cytometry and chemokines relevant for the function of DCs like DC-CK1, DC-STAMP, and IL-8 mRNA expression by real time PCR analysis. In project 2 of the current proposal we will identify the role of AhR and AhR/RelB activity in the differentiation process of bone marrow cells derived from C57BL/6 wild type and AhR null (AhR-/-) mice into DC. This study reveals a novel concept of the function of the AhR together with RelB and is critical in understanding how environmental toxicants like dioxins affect critical functions of the immune system and human health. PUBLIC HEALTH RELEVANCE: About 15 years ago Hankinson and coworkers identified the encoded protein ARNT, which is required for ligand-dependent translocation of the Aryl hydrocarbon Receptor (AhR) to the nucleus and its binding to Dioxin responsive elements (DRE) mediating induction of xenobiotic metabolizing enzymes (classical AhR/ARNT pathway), but the physiological role of the AhR remains a key question. The present study focuses on a new mechanism of cross talk between AhR and the NF- ?B member RelB (alternative AhR/RelB pathway), which suggests an example of how an activated AhR pathway may connect to the NF-?B subunit RelB in order to cooperatively regulate cytokine/chemokine expression as well as differentiation and function of dendritic cells. This work will help to understand the mechanism how environmental toxicants like dioxin or dioxin-like compounds, which activate the AhR, elicit immunotoxic effects and lead to adverse health effects.