Analysis of the domain specific functions of IKK1 and the role of the alternative NFkappaB pathway and IKK1 in germinal center B cells

转录因子NF κ B在参与先天性和适应性免疫机制的许多基因的诱导表达中起核心作用。导致NF κ B活化的两条主要信号通路被称为经典通路和旁路通路。替代NF κ B途径的特征在于IKK 1介导的p100磷酸化，其导致NF κ B二聚体p52/RelB的释放。IKK 1本身被NIK介导的磷酸化激活。最近，里克特教授和博士的研究小组显示，表达不能被NIK磷酸化的突变IKK 1分子（IKKAA）的B细胞不形成生发中心.拟议项目的目标是研究导致这种表型的机制。主要目的是分析B细胞中的NIK依赖性信号传导，确定IKKAA B细胞中的生化缺陷，分析IKK 1在抗原呈递细胞和浆细胞中的内在功能。此外，最近的研究表明IKK 1还具有NIK非依赖性、激酶非依赖性或核功能。为了深入了解IKK 1功能的这些方面，将研究表达IKK 1分子的B细胞，所述IKK 1分子a）不能进入细胞核（IKK 1 NLS）b）是激酶失活的（IKK 1 KM）c）是组成性活性的（IKK 1 EE）。

The transcription factor NFkappaB plays a central role in the inducible expression of many genes involved in the mechanisms of innate and adaptive immunity. The two dominant signaling pathways which can lead to the activation of NFkappaB are called the classical and the alternative pathway. The alternative NFkappaB pathway is characterised by the IKK1 mediated phosphorylation of p100 which leads to the release of the NFkappaB dimer p52/RelB. IKK1 itself is activated by NIK mediated phosphorylation. Very recently it was shown in the group of Prof.Dr.Rickert that B cells expressing a mutant IKK1 molecule that cannot be phosphorylated by NIK (IKKAA) do not form germinal centers. The goal of the proposed project is to study the mechanism leading to this phenotype. The main objectives are to analyse the NIK-dependent signaling in B cells, determine the biochemical defects in IKKAA B cells, analyze the intrinsic functions of IKK1 in antigen presenting- and plasma- cells. Further, recent studies indicate that IKK1 possesses also NIK- independent, kinase independent or nuclear functions. To gain insight into these aspects of IKK1 function, B cells expressing IKK1 molecules that a) are unable to enter he nucleus (IKK1NLS) b)are kinase inactive (IKK1KM) c)are constitutively active (IKK1EE) will be studied.