Nuclear receptors: action, functions, and roles in disea

核受体：在疾病中的作用、功能和作用

• 批准号: 7327214
• 负责人: Anton M Jetten
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7327214
• 关键词: Nuclear; receptors; action; functions; roles

I. RORgamma: The retinoid-related orphan receptor g (RORg) is a member of the nuclear receptor superfamily. To identify the physiological functions of RORg, mice deficient in RORg function were generated by targeted disruption. RORg -/- mice lack peripheral and mesenteric lymph nodes and Peyer?s patches indicating that RORg expression is indispensable for lymph node organogenesis. Although the spleen is enlarged, its architecture is normal. The number of peripheral blood CD3+ and CD4+ lymphocytes is reduced 6- and 10-fold, respectively, while the number of circulating B cells is normal. The thymus of RORg-/- mice contains 74.4+ 8.9% fewer thymocytes than that of wt mice. Flow cytometric analysis showed a decrease in the CD4+CD8+ subpopulation. TUNEL staining demonstrated a four-fold increase in apoptotic cells in the cortex of the thymus of RORg-/- mice. This was supported by the observed increase in annexin V-positive cells. RORg-/- thymocytes placed in culture exhibit a dramatic increase in the rate of "spontaneous" apoptosis. This increase is largely associated with CD4+CD8+ thymocytes and may at least in part be related to the greatly reduced level of expression of the anti-apoptotic gene Bcl-XL. Flow cytometric analysis demonstrated a six-fold rise in the percentage of cells in the S phase of the cell cycle among thymocytes from RORg-/- mice. Our observations indicate that RORg is essential for lymphoid organogenesis and plays an important regulatory role in thymopoiesis. Recently, we found that RORg-/- mice are highly susceptible to the development of T-cells lymphomas. Altered expression of ROR leads to deregulation of the differentiation of thymocytes, increased proliferation of double negative thymocytes, which in turn increases the frequency of tumor formation. Recent studies have demonstrated that ROR receptors play a regulatory role in various inflammatory respeonses. RORa mice are more susceptible to endotoxin-induced inflammation. Microarray analysis demonstarted a role for RORs in steroid and drug metabolism. II. TAK1: The nuclear orphan receptor TAK1 functions as a positive as well as a negative regulator of transcription; however little is know about factors mediating its activity. Yeast two-hybrid analysis using the ligand binding domain of TAK1 as bait identified a novel TAK1-interacting protein, referred to as TIP27. TIP27 is a 27 kD nuclear protein that contains two zinc finger motifs. Confocal microscopy using TIP27 and several deletion mutants showed that TIP27 localized to the nucleus and that the carboxyl terminus containing a putative nuclear localization signal is important for its nuclear localization. TIP27 mRNA is expressed in several adult tissues but is most highly expressed in testis where it is induced at a specific stage of spermatogenesis. Mammalian two-hybrid analysis showed that TIP27 interacts specifically with TAK1 and not with several other nuclear receptors tested. Deletion mutation analysis determined that the region between Asp39 and Lys79 of TIP27, referred to as TAK1-interaction domain (TID), is critical for its interaction with TAK1. Moreover, it demonstrated that the TAK1-LBD from H3 till the carboxyl terminus is required for optimal interaction with TIP27. Pull-down assays demonstrated that TIP27 physically interacts with TAK1 and supported the importance of the TID. TIP27 is a strong repressor of DR1-dependent transcriptional activation by TAK1. This repression does not involve inhibition of TAK1 homodimerization or DR1 binding but appears to due to an inhibition of the recruitment of co-activators. Our studies indicate that TIP27 is an effective repressor of transcriptional activation by TAK1 and, therefore, may play a critical role in the regulation of several physiological functions by TAK1. Generation of TAK1 knockout mice revealed several phenotypes that are currently being investigated. The nuclear protein RAP80 was shown to interact with the estrogen receptor alpha in an agonist dependent manner. In addition, RAP80 was implicated in DNA repair. The role of RAP80 in tumorigenesis is being investigated.

I. RORgamma：类视黄醇相关孤儿受体 g (RORg) 是核受体超家族的成员。为了确定 RORg 的生理功能，通过定向破坏产生了 RORg 功能缺陷的小鼠。 RORg -/- 小鼠缺乏外周和肠系膜淋巴结以及派尔氏淋巴结，表明 RORg 表达对于淋巴结器官发生是必不可少的。尽管脾脏增大，但其结构正常。外周血CD3+和CD4+淋巴细胞的数量分别减少6倍和10倍，而循环B细胞的数量正常。 RORg-/-小鼠的胸腺含有比wt小鼠少74.4+8.9%的胸腺细胞。流式细胞分析显示 CD4+CD8+ 亚群减少。 TUNEL 染色显示 RORg-/- 小鼠胸腺皮质中的凋亡细胞增加了四倍。观察到的膜联蛋白 V 阳性细胞的增加支持了这一点。置于培养物中的RORg-/-胸腺细胞表现出“自发”凋亡率的显着增加。这种增加很大程度上与 CD4+CD8+ 胸腺细胞有关，并且可能至少部分与抗凋亡基因 Bcl-XL 的表达水平大大降低有关。流式细胞术分析表明，RORg-/- 小鼠胸腺细胞中处于细胞周期 S 期的细胞百分比增加了六倍。我们的观察表明，RORg 对于淋巴器官发生至关重要，并在胸腺生成中发挥重要的调节作用。最近，我们发现 RORg-/- 小鼠非常容易发生 T 细胞淋巴瘤。 ROR表达的改变导致胸腺细胞分化失调，双阴性胸腺细胞增殖增加，进而增加肿瘤形成的频率。最近的研究表明，ROR 受体在多种炎症反应中发挥调节作用。 RORa 小鼠更容易受到内毒素引起的炎症的影响。微阵列分析证明了 ROR 在类固醇和药物代谢中的作用。 二. TAK1：核孤儿受体 TAK1 充当转录的正调节因子和负调节因子；然而，人们对调节其活动的因素知之甚少。使用 TAK1 的配体结合域作为诱饵进行酵母双杂交分析，鉴定出一种新型 TAK1 相互作用蛋白，称为 TIP27。 TIP27 是一种 27 kD 核蛋白，包含两个锌指基序。使用 TIP27 和几个缺失突变体的共聚焦显微镜显示，TIP27 定位于细胞核，并且含有假定的核定位信号的羧基末端对其核定位很重要。 TIP27 mRNA 在多种成人组织中表达，但在睾丸中表达最高，在精子发生的特定阶段被诱导。哺乳动物双杂交分析表明，TIP27 与 TAK1 特异性相互作用，而不与测试的其他几种核受体相互作用。缺失突变分析确定 TIP27 的 Asp39 和 Lys79 之间的区域（称为 TAK1 相互作用域 (TID)）对于其与 TAK1 的相互作用至关重要。此外，它证明从 H3 到羧基末端的 TAK1-LBD 是与 TIP27 最佳相互作用所必需的。 Pull-down 测定表明 TIP27 与 TAK1 发生物理相互作用，并支持了 TID 的重要性。 TIP27 是 TAK1 依赖 DR1 的转录激活的强阻遏物。这种抑制并不涉及抑制 TAK1 同二聚化或 DR1 结合，但似乎是由于抑制了共激活剂的招募。我们的研究表明，TIP27 是 TAK1 转录激活的有效抑制因子，因此可能在 TAK1 多种生理功能的调节中发挥关键作用。 TAK1 敲除小鼠的产生揭示了目前正在研究的几种表型。核蛋白 RAP80 显示以激动剂依赖性方式与雌激素受体 α 相互作用。此外，RAP80 还参与 DNA 修复。 RAP80 在肿瘤发生中的作用正在研究中。