Inherited Disorders of Lymphocyte Development

描述（由申请人提供）：对人类严重联合免疫缺陷（SCID）分子基础的研究开创了一个新时代，改善了这些罕见但严重的遗传疾病的诊断和治疗，也为免疫学和淋巴细胞发育领域做出了贡献。虽然现在已知许多人类SCID的疾病基因，但对“漏性”或“部分性”SCID（也称为联合免疫缺陷（CID））知之甚少；未知基因型的SCID和CID病例为进一步发现提供了机会。此外，小鼠提供了解剖淋巴细胞发育途径的能力，我们已经发现了一种新的小鼠SCID形式，缺乏一种预测的转录因子Zbtb1。缺乏Zbtb1的小鼠没有T细胞，但B系发育仅轻度受损。这种T-B+ SCID模型很重要，因为它的表型类似于人类，在常见的g链（gc）受体、IL-7受体a链（IL7Ra）和Janus激酶3 （Jak3）中存在细胞因子信号通路缺陷，而缺乏这些蛋白的小鼠敲除与人类不同，具有T细胞，但缺乏B细胞（T-B+）。我们将结合人类患者和小鼠模型的资源来解决淋巴细胞发育和功能缺陷的发病机制。来自SCID/CID患者的样本将被评估已知SCID基因的缺陷，而没有基因型分配的病例将被研究新的候选基因的缺陷。同时，我们将定义Zbtb1缺陷小鼠的特异性发育和功能性淋巴样表型，以揭示Zbtb1在小鼠T和NK细胞发育以及B细胞分化和功能中的正常作用。比较Zbtb1-小鼠，细胞因子信号缺陷的人，和正常的人造血干细胞（HSC），其中Zbtb1基因表达被RNAi敲低，将为淋巴细胞的发育提供新的见解。因此，本提案的目标是：(i)从没有已知基因缺陷的SCID和CID患者中收集样本；（ii）探讨Zbtb1-小鼠B细胞损伤的SCID发病机制；（iii）使用平行的体外和体内策略来比较野生型与Zbtb1敲除小鼠以及正常与Zbtb1敲除小鼠脐带血干细胞的HSC淋巴细胞发育潜力；（iv）找到Zbtb1相互作用的伙伴和基因靶标，这些靶标（连同Zbtb1本身）将被评估可能导致人类SCID的突变。

DESCRIPTION (provided by applicant): Studies of the molecular basis of human severe combined immunodeficiency (SCID) have ushered in a new era of improved diagnosis and treatment of these rare, but serious genetic disorders and also contributed to the fields of immunology and lymphocyte development. While many disease genes for human SCID are now known, less is known about "leaky" or "partial" SCID, also called combined immunodeficiency (CID); both SCID and CID cases of unknown genotype provide opportunities for further discovery. In addition, the mouse offers the power to dissect lymphoid developmental pathways, and we have discovered a new form of mouse SCID, deficiency of a predicted transcription factor Zbtb1. Mice lacking Zbtb1 have no T cells, but B lineage development is only mildly impaired. This T-B+ SCID model is important because its phenotype resembles that of humans with cytokine signaling pathway defects in the common g chain (gc) receptor, the IL-7 receptor a chain (IL7Ra), and Janus kinase 3 (Jak3), whereas the mouse knockouts lacking these proteins differ from humans in having T cells, but lacking B cells (T-B+). We will combine resources from human patients and mouse models to address the pathogenesis of lymphocyte developmental and functional defects. Samples from patients with SCID/CID will be assessed for defects in known SCID genes, and the cases remaining without a genotype assignment will be studied for defects in new gene candidates. Meanwhile, we will define the specific developmental and functional lymphoid phenotype of Zbtb1 deficient mice to uncover the normal role of Zbtb1 in mouse T and NK cell development and B cell differentiation and function. Comparisons between the Zbtb1- mouse, humans with cytokine signaling defects, and normal human hematopoietic stem cells (HSC) in which ZBTB1 gene expression is knocked down by RNAi will provide new insight into lymphoid development. Thus the goals of this proposal are to (i) assemble samples from SCID and CID patients without known gene defects; (ii) explore SCID pathogenesis of B cell impairment in Zbtb1- mice; (iii) use parallel in vitro and in vivo strategies to compare lymphoid developmental potential of HSC from wild type vs. Zbtb1 knockout mice and normal vs. ZBTB1 knockdown cord blood stem cells; and (iv) find Zbtb1 interacting partners and gene targets, which (along with ZBTB1 itself) will be assessed for mutations that may cause human SCID. PUBLIC HEALTH RELEVANCE: The development of lymphocytes from blood-forming stem cells is incompletely understood, but critically important for treating humans with severe combined immunodeficiency (SCID), other immune and blood diseases, and cancers. We study humans and mice with SCID to find their underlying gene defects and to learn about pathways essential for lymphocyte maturation. We discovered that mice lacking Zbtb1 (a previously unstudied zinc finger protein) cannot form T lymphocytes, though B lymphocytes are present. Zbtb1 is related to transcription factors that repress expression of their target genes. We will investigate how Zbtb1 and its targets function in developing mouse and human lymphoid cells and determine whether defects in Zbtb1 or the genes it acts upon cause human disorders of immunity.