NR4A orphan nuclear receptor family in peripheral blood eosinophils from patients with atopic dermatitis and apoptotic eosinophils in vitro

To identify novel genes related to the clinical signs of atopic dermatitis (AD), differentially expressed genes were sought in peripheral blood eosinophils from both AD patients and healthy volunteers. RNA was prepared from eosinophils, expression of various genes was monitored using the Affymetrix GeneChip, and expression was quantified by real-time RT-PCR. Two genes, Nur77 and NOR1, members of NR4A orphan nuclear receptor family, were expressed at a significantly higher level in AD patients than in healthy volunteers. Expression of another gene in the NR4A receptor family, Nurr1, was also higher in AD patients than in healthy volunteers. When peripheral blood leukocytes from healthy volunteers were fractionated, NOR1 expression was highest in eosinophils, but expression of Nur77 and Nurr1 genes was not eosinophil-specific. Extremely intense apoptosis was induced in both eosinophils and an eosinophil cell line, AML14.3D10, by treatment with antibody (Ab) to both CD30 and Fas. Rapid expression of the genes for the NR4A receptor family was observed with anti-CD30 Ab treatment but not with anti-Fas Ab. The NR4A orphan nuclear receptor family gene expression and the subsequent eosinophil apoptosis were downregulated by the MAPK inhibitor, U0126. These results suggest that the expression of the NR4A receptor family genes through CD30 signaling may regulate eosinophil apoptosis in allergic conditions such as AD.     

Nuclear receptors Nur77 and Nurr1 modulate mesenchymal stromal cell migration

Detailed understanding of mesenchymal stromal cells (MSC) migration is imperative for future cellular therapies. To identify genes involved in the process of MSC migration, we generated gene expression profiles of migrating and nonmigrating fetal bone marrow MSC (FBMSC). Only 12 genes showed differential expression in migrating versus nonmigrating FBMSC. The nuclear receptors Nur77 and Nurr1 showed the highest expression in migratory MSC. Nur77 and Nurr1 are members of NR4A nuclear orphan receptor family, and we found that their expression is rapidly increased upon exposure of FBMSC to the migratory stimuli stromal-derived factor-1α (SDF-1α) and platelet-derived growth factor-BB. Lentiviral expression of Nur77 or Nurr1 resulted in enhanced migration of FBMSC toward SDF-1α compared with mock-transduced FBMSC. Analysis of the cell cycle, known to be involved in MSC migration, revealed that expression of Nur77 and Nurr1 decreases the proportion of cells in S-phase compared with control cells. Further, gain-of-function experiments showed increased hepatocyte growth factor expression and interleukin (IL)-6 and IL-8 production in MSC. Despite the altered cytokine profile, FBMSC expressing Nur77 or Nurr1 maintained the capacity to inhibit T-cell proliferation in a mixed lymphocyte reaction. Our results demonstrate that Nur77 and Nurr1 promote FBMSC migration. Modulation of Nur77 and Nurr1 activity may therefore offer perspectives to enhance the migratory potential of FBMSC which may specifically regulate the local immune response.     

T淋巴细胞凋亡及其调控机制的研究进展

T淋巴细胞凋亡是免疫系统维持稳定的一种重要机制,在多种疾病中起着重要作用.fas/FasL、Trail/trail受体等死亡受体信号传导可介导T淋巴细胞凋亡,线粒体在诱导细胞凋亡中也起着重要作用;而bcl-2家族、v-FLIP等抗细胞凋亡蛋白和转录因子Nur77等对T淋巴细胞凋亡起调控作用.     

Protein kinase C regulates mitochondrial targeting of Nur77 and its family member Nor‐1 in thymocytes undergoing apoptosis

Nur77 orphan steroid receptor and its family member Nor‐1 are required for apoptosis of developing T cells. In thymocytes, signals from the TCR complex induce Nur77 and Nor‐1 expression followed by translocation from the nucleus to mitochondria. Nur77 and Nor‐1 associate with Bcl‐2 in the mitochondria, resulting in a conformation change that exposes the Bcl‐2 BH3 domain, a presumed pro‐apoptotic molecule of Bcl‐2. As Nur77 and Nor‐1 are heavily phosphorylated, we examined the requirement of Nur77 and Nor‐1 phosphorylation in mitochondria translocation and Bcl‐2 BH3 exposure. We found that HK434, a PKC agonist, in combination with calcium ionophore, can induce Nur77 and Nor‐1 phosphorylation, translocation, Bcl‐2 BH3 exposure and thymocyte apoptosis. Inhibitors of both classical and novel forms of PKC were able to block this process. In contrast, only the general but not classical PKC‐specific inhibitors were able to block the same process initiated by PMA, a commonly used PKC agonist. These data demonstrate a differential activation of PKC isoforms by PMA and HK434 in thymocytes, and show the importance of PKC in mitochondria translocation of Nur77/Nor‐1 and Bcl‐2 conformation change during TCR‐induced thymocyte apoptosis.     

‘Nur'turing tumor T cell tolerance and exhaustion: novel function for Nuclear Receptor Nur77 in immunity

The nuclear receptor Nur77 is expressed in a multitude of tissues, regulating cell differentiation and homeostasis. Dysregulation of Nur77 signaling is associated with cancer, cardiovascular disease, and disorders of the CNS. The role of Nur77 in T cells has been studied for almost 30 years now. There is a clear appreciation that Nur77 is crucial for apoptosis of self-reactive T cells. However, the regulation and function of Nur77 in mature T cells remains largely unclear. In an exciting development, Nur77 has been recently demonstrated to impinge on cancer immunotherapy involving chimeric antigen receptor (CAR) T cells and tumor infiltrating lymphocytes (TILs). These studies indicated that Nur77 deficiency reduced T cell tolerance and exhaustion, thus raising the effectiveness of immune therapy in mice. Based on these novel insights, it may be proposed that regulation of Nur77 activity holds promise for innovative drug development in the field of cellular immunotherapy in cancer. In this review, we therefore summarize the role of Nur77 in T cell selection and maturation; and further develop the idea of targeting its activity in these cells as a potential strategy to augment current cancer immunotherapy treatments.     

核受体NR6A1通过上调RIPK3基因表达诱导血管平滑肌细胞凋亡

目的:探讨核受体亚家族6A1(NR6A1)对血管平滑肌细胞凋亡的影响及可能的分子机制。方法:将腺病毒Ad-NR6A1感染大鼠血管平滑肌细胞,分别在感染后0 h、24 h和48 h时进行MTT实验,以时间为横坐标,A570为纵坐标绘制细胞生长曲线,观察NR6A1对细胞生长的影响;进行DAPI染色、TUNEL染色及caspase活性检测,观察细胞凋亡情况;进一步通过基因芯片技术,寻找NR6A1的靶基因;采用siRNA介导的基因沉默技术,观察受体相互作用丝氨酸/苏氨酸蛋白激酶3(RIPK3)基因沉默对NR6A1诱导的血管平滑肌细胞凋亡的影响。结果:腺病毒Ad-NR6A1感染细胞48 h时,NR6A1过表达组细胞数量较对照组(重组腺病毒载体Ad-Lac Z)明显减少;DAPI染色显示NR6A1过表达诱导血管平滑肌细胞出现核浓缩和核碎裂的凋亡表型,TUNEL染色显示NR6A1过表达引起细胞凋亡,caspase活性检测结果显示NR6A1过表达细胞内caspase-3、caspase-8和caspase-9活性均较对照组高;基因芯片技术检测发现,NR6A1过表达上调血管平滑肌细胞中RIPK3基因表达;RIPK3基因沉默可以显著抑制NR6A1诱导的平滑肌细胞凋亡。结论:NR6A1通过上调RIPK3基因表达诱导血管平滑肌细胞凋亡。     

Post-synaptic density-93 mediates tyrosine-phosphorylation of the N-methyl-D-aspartate receptors

Src family protein kinases (SFKs) -mediated tyrosine-phosphorylation regulates N-methyl-d-aspartate (NMDA) receptor synaptic function. Some members of the membrane-associated guanylate kinase (MAGUK) family of proteins bind to both SFKs and NMDA receptors, but it is unclear whether the MAGUK family of proteins is required for SFKs-mediated tyrosine-phosphorylation of the NMDA receptors. Here, we showed by co-immunoprecipitation that post-synaptic density (PSD) -93, a member of the MAGUK family of proteins, interacts with the NMDA receptor subunits NR2A and NR2B as well as with Fyn, a member of the SFKs, in mouse cerebral cortex. Using a biochemical fractionation approach to isolate subcellular compartments revealed that the expression of Fyn, but not of other members of the SFKs (Lyn, Src, and Yes), was significantly decreased in synaptosomal membrane fractions derived from the cerebral cortex of PSD-93 knockout mice. Interestingly, we found that PSD-93 disruption causes reduction of tyrosine-phosphorylated NR2A and NR2B in the same fraction. Moreover, PSD-93 deletion markedly blocked the SFKs-mediated increase in tyrosine-phosphorylated NR2A and NR2B through the protein kinase C pathway after induction with 4-phorbol 12-myristate 13-acetate in cultured cortical neurons. Our findings indicate that PSD-93 appears to mediate tyrosine-phosphorylation of the NMDA receptors and synaptic localization of Fyn.     

The Impact of CB1 Receptor on Nuclear Receptors in Skeletal Muscle Cells

Cannabinoids are abundant signaling compounds; their influence predominantly arises via engagement with the principal two G-protein-coupled cannabinoid receptors, CB1 and CB2. One suggested theory is that cannabinoids regulate a variety of physiological processes within the cells of skeletal muscle. Earlier publications have indicated that expression of CB1 receptor mRNA and protein has been recognized within myotubes and tissues of skeletal muscle from both murines and humans, thus representing a potentially significant pathway which plays a role in the control of skeletal muscular activities. The part played by CB1 receptor activation or inhibition with respect to these functions and relevant to targets in the periphery, especially skeletal muscle, is not fully delineated. Thus, the aim of the current research was to explore the influence of CB1 receptor stimulation and inhibition on downstream signaling of the nuclear receptor, NR4A, which regulates the immediate impacts of arachidonyl-2′-chloroethylamide (ACEA) and/or rimonabant in the cells of skeletal muscle. Murine L6 skeletal muscle cells were used in order to clarify additional possible molecular signaling pathways which contribute to alterations in the CB1 receptor. Skeletal muscle cells have often been used; it is well-documented that they express cannabinoid receptors. Quantitative real-time probe-based polymerase chain reaction (qRT-PCR) assays are deployed in order to assess the gene expression characteristics of CB1 receptor signaling. In the current work, it is demonstrated that skeletal muscle cells exhibit functional expression of CB1 receptors. This can be deduced from the qRT-PCR assays; triggering CB1 receptors amplifies both NR4A1 and NR4A3 mRNA gene expression. The impact of ACEA is inhibited by the selective CB1 receptor antagonist, rimonabant. The present research demonstrated that 10 nM of ACEA notably amplified mRNA gene expression of NR4A1 and NR4A3; this effect was suppressed by the addition of 100 nM rimonabant. Furthermore, the CB1 receptor antagonist led to the downregulation of mRNA gene expression of NR4A1, NR4A2 and NR4A3. In conclusion, in skeletal muscle, CB1 receptors were recognized to be important moderators of NR4A1 and NR4A3 mRNA gene expression; these actions may have possible clinical benefits. Thus, in skeletal muscle cells, a possible physiological expression of CB1 receptors was identified. It is as yet unknown whether these CB1 receptors contribute to pathways underlying skeletal muscle biological function and disease processes. Further research is required to fully delineate their role(s).     

孤儿核受体Nur77激动剂CsnB对人HepG2肝癌细胞胆固醇代谢调控基因的影响

目的探讨孤儿核受体Nur77激动剂CsnB对人HepG2肝癌细胞胆固醇代谢调控基因的影响。方法利用CsnB诱导Nur77在人HepG2肝癌细胞中的高表达。通过与CsnB相同剂量的DMSO对照组的比较,观察CsnB作用不同时间后肝细胞胆固醇代谢相关重要基因的变化,如低密度脂蛋白受体（LDLR）、HMGCoA还原酶（HMGCR）和肝X受体α（LXRα）。结果 10μg/ml终浓度CsnB刺激HepG2细胞可以达到Nur77的高表达,并在作用1.5h后表达量达到高峰。相同浓度CsnB刺激HepG2细胞后,LDLR与HMGCR随时间的延长逐渐下降,并且两种基因在CsnB处理24h后的表达量与0h比较,差异有统计学意义（P〈0.05）;而LXRα的表达量变化不大。结论 CsnB可以有效诱导Nur77在HepG2细胞中的高表达,其对于肝癌细胞胆固醇代谢调控基因的影响主要表现为LDLR与HMGCR的下调。