The Role of NEMO Ubiquitination in EDA-ID

描述（由申请人提供）：NF-kB信号是免疫缺陷和炎症疾病的中心。NF-kB信号转导的一个关键调节因子NEMO最近被发现在一种称为免疫缺陷无汗性（低水性）外胚层发育不良（EDA-ID）的免疫缺陷疾病中发生突变。EDA-ID患者易受革兰氏阳性菌感染，从分子上讲，由于nemo的亚型突变，NF-kB信号通路功能失调是罪魁祸首。虽然NF-kB通路已被充分研究，已成为炎症信号转导的范式，但近年来这种范式发生了转变，人们认识到该通路的信号转导强度和协调严重依赖赖氨酸-63 （K63）连接的多泛素化。NEMO最近被证明含有一个泛素结合域，这是NF:B信号传导所必需的，NEMO本身在两个位点上被k63多泛素化，以响应固有免疫刺激（NOD2（克罗恩病易感性蛋白）和toll样受体（TLR）激活）。NEMO泛素化是优化NF:B信号传递的必要条件（1,2,6,13,26）。EDA-ID中nemo点突变的谱和位置表明，从生物化学角度来看，它们可能在先天免疫刺激下干扰nemo的泛素结合和/或k63连接的nemo多泛素化。此外，EDA-ID中不同的免疫表型和免疫缺陷提示特定突变的细胞类型特异性。最后，该领域很难将NEMO的泛素结合与K63-linked NEMO的多泛素化分离开来，因为它涉及功能并最终涉及NF: b诱导的基因表达。所有这些困难都表明，需要系统地评估EDA-ID相关NEMO突变在泛素结合、k63相关NEMO多泛素化和nf - kb相关基因表达方面的作用。这些困难也表明需要有缺陷的NEMO泛素化的体内模型来解释其在体内NF: b依赖性基因表达和炎症和免疫缺陷疾病中的作用。拨款申请旨在回答这些关键问题。

DESCRIPTION (provided by applicant): NF-kB signaling lies at the center of Immunodeficiency and Inflammatory diseases. A key regulator of NF-kB signal transduction, NEMO, has recently been found to be mutated in an Immunodeficiency Disorder called called Anhidrotic (hypohydrotic) Ectodermal Dysplasia with Immunodeficiency (EDA-ID). Patients with EDA-ID are susceptible to infection with gram-positive organisms, and molecularly, a dysfunctional NF-kB signaling pathway, owing to hypomorphic mutations in nemo is to blame. While the NF-kB pathway is so well-studied that it has become a paradigm for inflammatory signal transduction, this paradigm has shifted in recent years with the recognition that this pathways signal transduction strength and coordination is critically dependent on Lysine-63 (K63)-linked polyubiquitination. NEMO was very recently shown to contain a ubiquitin binding domain that is essential for NF:B signaling, and NEMO, itself, is K63-polyubiquitinated on two sites in response to innate immune stimulation (NOD2 (Crohn's Disease-susceptibility protein) and Toll-like Receptor (TLR) activation). This NEMO ubiquitination is necessary for optimal NF:B signaling (1, 2, 6, 13, 26). The spectrum and location of point mutations of nemo in EDA-ID suggest that biochemically, they may be interfering with ubiquitin binding by NEMO and/or K63-linked polyubiquitination of NEMO in response to innate immune stimuli. In addition, the varied immunologic phenotypes and immunodeficiencies in EDA-ID suggest cell-type specificity in regards to the particular mutations. Lastly, it has been difficult for the field to uncouple ubiquitin binding by NEMO from K63-linked polyubiquitination of NEMO as it relates to function and ultimately, NF:B-induced gene expression. All these difficulties point to the need to systematically evaluate EDA-ID- associated NEMO mutations in regards to ubiquitin binding, K63-linked polyubiquitination of NEMO and NF-kB-associated gene expression. These difficulties also point to a need for an in vivo model of defective NEMO ubiquitination to decipher its role in in vivo NF:B-dependent gene expression and inflammatory and immunodeficiency disorders. The grant application aims to answer these key questions. PUBLIC HEALTH RELEVANCE: The ability to determine the genetics of susceptibility to infectious disease has led to the identification of novel forms of immunodeficiency, and the challenge is to translate these genetic findings into biochemical mechanisms of disease to both better understand the disease and allow better treatment for that disease. NEMO, a protein that is central to the major inflammatory signaling pathway is mutated in a disease called EDA-ID, a disease that is characterized by susceptibility to bacterial infections. This grant aims to determine how NEMO is faulty in EDA-ID and to generate a mouse model that might mimic many of the features of EDA-ID in hopes that this might lead to a better understanding of and better treatments for this disease.