Structure-function relationship of NFkB p65

我们以前已经证明，在细胞激活后，丝氨酸536处p65的磷酸化被差异地招募到选择性启动子中。我们最近已经证明，p65结合位点和特定基因转录起始点之间的距离决定了p65是否需要在丝氨酸536上被磷酸化。P65的磷酸化不参与增强体的形成，在增强体的形成中，组蛋白修饰酶需要招募到近端的启动子。这些发现表明，p65的磷酸化和启动子的顺式作用元件调控着各种NFkB反应基因。我们目前正在研究p65的不同磷酸化位点在控制p65反应基因周围的染色质结构中的作用。我们还在研究IKB各成员如何调节磷酸化p65的核转位。除了丝氨酸536外，p65的丝氨酸529的磷酸化也被证明调节转录活性。我们目前正在研究丝氨酸529和536在调节染色质结构中的磷酸化之间的关系。 我们以前已经证明，p65在丝氨酸536位的磷酸化导致CSF2基因表达的增加。最近的研究表明，在小鼠成纤维细胞中，淋巴毒素-β受体(LTbR)信号通路诱导了Ikka对丝氨酸536位p65的磷酸化。我们观察到，激动型抗LTbR抗体处理3T3成纤维细胞后，p65在丝氨酸536位发生了磷酸化，而CSF2基因没有表达。然而，抗LTbR抗体可协同增加肿瘤坏死因子介导的CSF2的表达。这种协同增强需要NIK的激活，并通过另一条NFkB途径传递信号。此外，在肿瘤坏死因子介导的CSF2基因表达的LTbR启动过程中，观察到p65和RelB的核移位和募集到CSF2启动子。我们目前正在研究引爆的机制。

We have previously demonstrated that the phosphorylation of p65 at serine 536 was differentially recruited to selective promoters following cell activation. We have recently demonstrated that the distance between the site of p65 binding and the transcription start site of a particular gene determines if p65 needs to be phosphorylated on serine 536. The phosphorylation of p65 was not involved in the formation of an enhanceosome, where the recruitment of histone modifying enzymes to proximal promoters was required. These findings suggested that the phosphorylation of p65 and the cis-acting elements of the promoter regulate the various NFkB responsive genes. We are currently investigating the role of various phosphorylation sites of p65 in controling the chromatin architecture surrounding p65 responsive genes. We are also examining how the various IkB members regulate the nuclear translocation of phosphorylated p65. In addition to serine 536, the phosphorylation of serine 529 of p65 has been shown to regulate transcriptional activity. We are currently investigating the relationship between the phosphorylation of serines 529 and 536 in regulating the chromatin architecture. We have shown previously that the phosphorylation of p65 at serine 536 resulted in an increase in Csf2 gene expression. Recently, it has been shown that the phosphorylation of p65 at serine 536 by IKKa was induced by lymphotoxin-beta receptor (LTbR) signaling in mouse fibroblast. We have observed that the treatment of 3T3 fibroblast cells with agonistic anti-LTbR antibody resulted in the phosphorylation of p65 at serine 536, but no expression of Csf2 gene. However, priming with anti-LTbR antibody resulted in a synergistic increase of TNF-mediated Csf2 expression. The synergistic enhancement required the activation of NIK and signaling through the alternative NFkB pathway. Furthermore, the nuclear translocation and recruitment of both p65 and RelB to the Csf2 promoter were observed during the LTbR priming of TNF-mediated Csf2 gene expression. We are currently examining the mechanism of priming.