Elucidating IKK1 function in germinal center B cell differentiation

描述(申请人提供)：核因子-kB信号受IKB激酶复合体调控，由IKK1、IKK2和NEMO组成。然而，最近的研究表明，IKK1和IKK2在很大程度上具有不同的功能。在拟议的工作中，我们将确定IKK1在GC B细胞中的内在功能。我们最近报道，表达突变的IKK1分子的B细胞不能被Nik(IKK1AA)磷酸化，不形成GC。在这里，我们将通过CD40/BAFF-R/TNF-R2信号和T细胞共刺激来研究IKK1在GC中依赖的功能，以确定这一发现的基础。我们还将使用免疫组织化学方法在原位评估IKK1通路的激活。为了补充这些研究，将产生表达条件IKK1FLOX/FLOX等位基因的小鼠，使其与表达可诱导的B细胞特异性Cre的小鼠杂交，从而使我们能够在GC反应之前和期间/之后识别依赖IKK1的B细胞功能。这些小鼠将与携带突变的条件性IKK1等位基因的小鼠杂交，以探索IKK1的区域特异性功能。总之，这些拟议的研究将为IKK1在体内的功能提供明确的机制洞察力。 公共卫生相关性：生发中心是感染或免疫后在次级淋巴组织中形成的微环境。正是在这里，B淋巴细胞被选为高亲和力的记忆B细胞或产生抗体的细胞。因此，理解引导生发中心B细胞发育的分子线索对于理解体液免疫的基础至关重要。

DESCRIPTION (provided by applicant): NF-kB signaling is regulated by the IkB kinase complex, consisting of IKK1, IKK2 and NEMO. However, recent studies have shown that IKK1 and IKK2 have largely distinct functions. In the proposed work, we will determine the intrinsic functions of IKK1 in GC B cells. We have recently reported that B cells expressing a mutant IKK1 molecule that cannot be phosphorylated by NIK (IKK1AA) do not form GCs. Herein we will determine the basis for this finding by examining IKK1- dependent functions in the GC via CD40/BAFF-R/TNF-R2 signaling and T cell costimulation. We will also assess activation of the IKK1 pathway in situ using immunohistochemical approaches. To complement these studies, mice will be generated expressing conditional IKK1flox/flox alleles to intercross with inducible B cell-specific Cre-expressing mice, thus allowing us to identify IKK1-dependent B cell functions prior to and during/after the GC reaction. These mice will be intercrossed with mice bearing mutant conditional IKK1 alleles to probe domain-specific functions of IKK1. Together, the proposed studies will provide definitive mechanistic insight into IKK1 function in vivo. PUBLIC HEALTH RELEVANCE: Germinal centers are microenvironments that form in the secondary lymphoid tissues following infection or immunization. It is here where B lymphocytes are selected to be high-affinity memory B cells or antibody-producing cells. Thus, understanding the molecular cues that guide germinal center B cell development is critical to understanding the basis of humoral immunity.