MURINE MODELS OF SEVERE COMBINED IMMUNODEFICIENCIES

本申请旨在为产生小鼠免疫缺陷模型的研究提供新的资助。先前申请的主要目标是建立Btk-缺乏症的小鼠模型，并确定参与V(D)J重组和DNA修复的新基因，作为基因靶向研究的候选基因，以产生新的SCID模型。所有目标都成功实现了。目前的应用建立在后一组研究的基础上，以进一步评估V(D)J重组和DNA修复因子对免疫缺陷的影响。V(D)J重组涉及淋巴细胞特异性活性，包括重组激活基因1和2 （RAG-1和RAG-2）产物以及一般表达活性，其中包括dna依赖性蛋白激酶和XRCC4的组分。在这项应用支持的研究中，我们已经证明这些基因的表达缺陷会导致小鼠严重的综合免疫缺陷。在我们提出的研究中，我们的目标是表征XRCC4缺陷小鼠的新型免疫缺陷表型，并继续努力生成正常免疫功能可能需要的几种额外DNA修复基因的小鼠模型。我们还将使用几种不同的方法来继续鉴定参与V(D)J重组/DNA修复的新基因，并评估它们在免疫缺陷中的潜在作用。最后，我们将采用我们实验室生成的快速方法来生成和评估携带特定RAG-1或RAG-2突变的小鼠，其中一些突变被怀疑有助于人类复杂的免疫缺陷表型。

This application seeks to renew funding for studies aimed at generating murine immunodeficiency models. The major goals of the previous application were to generate a murine model of Btk- deficiency and to identify novel genes involved in V(D)J recombination and DNA repair as candidates for gene targeting studies to generate novel SCID models. All goals were successfully achieved. The current application builds on the latter set of studies to further evaluate the potential of V(D)J recombination and DNA repair factors to contribute to immunodeficiencies. V(D)J recombination involves lymphocyte specific activities including the recombination activating gene 1 and 2 (RAG-1 and RAG-2) products as well as generally expressed activities, which include components of the DNA-dependent protein kinase and XRCC4. In studies supported by this application, we have already shown that defects in expression of such genes can lead to severe combined immune deficiencies in mice. In our proposed studies, we aim to characterize the novel immunodeficient phenotype of XRCC4 deficient mice and to continue ongoing efforts to generate murine models of several additional DNA repair genes potentially required for normal immune function. We will also use several different approaches to continue to identify novel genes involved in V(D)J recombination/DNA repair and to evaluate their potential role in immunodeficiencies. Finally, we will employ a rapid approach generated in our laboratory to generate and evaluate mice harboring specific RAG-1 or RAG-2 mutations, some of which are suspected to contribute to complex immunodeficient phenotypes in humans.