BRIGHT FUNCTION IN IMMUNODEFICIENCY DISEASE

X-连锁免疫缺陷（xid）小鼠和X-连锁免疫缺陷（xid）人类 无丙种球蛋白血症（XLA），表现出较低的血清免疫球蛋白水平 比正常人。许多患者缺乏可检测到的B淋巴细胞。 布鲁顿酪氨酸激酶（BTK）在xid和XLA中均发生突变，但在XLA中， 这种激酶突变导致B细胞缺陷的机制是 未知Bright，免疫球蛋白重链（B细胞调节因子 转录），是主要在B中表达的70 kDa DNA结合蛋白 淋巴细胞它与鼠免疫球蛋白内的几个区域结合 重链位点，并已与增加， 免疫球蛋白RNA水平。明亮的表达和DNA结合活性可以 在正常成人脾脏中，可通过多种刺激诱导。最近 研究表明，来自XID小鼠的刺激淋巴细胞不产生 Bright DNA结合活性;即使Bright蛋白不存在。 其他实验表明，Bright和BTK在正常情况下直接相互作用。 小鼠因此，Bright活性可能需要功能性BTK。 拟议的研究将解决缺陷BTK导致 不活跃的Bright形式，至少可以部分解释低 在xid中观察到的血清免疫球蛋白水平，并且通过扩展，XLA。的 具体目标是。1)来研究BTK对Bright DNA的重要性 通过共表达、免疫沉淀和鉴定的结合活性 翻译后修饰，2）以确定功能性Bright 存在于来自XLA患者的B细胞中，3） 确定Bright与xid表型的关系， 显性阴性形式的Bright并在转基因小鼠中表达， 4)为了确定Bright在免疫球蛋白基因座中的功能， 体外转录和拓扑异构酶测定，以及5）鉴定 可能受Bright相互作用调控的其他基因 移位测定和抗体促进克隆。这些研究将提供 对Bright在xid和人类中的潜在作用的重要新见解 免疫缺陷病，XLA，并将有助于我们了解 免疫球蛋白基因调控

X-linked immunodeficient (xid) mice and humans with X-linked agammaglobulinemia (XLA), exhibit lower levels of serum immunoglobulin than normal individuals. Many patients lack detectable B lymphocytes. Bruton's tyrosine kinase (BTK) is mutated in both xid and XLA, but the mechanism by which mutations in this kinase cause B cell defects is unknown. Bright, (B cell regulator of immunoglobulin heavy chain transcription), is a 70 kDa DNA-binding protein expressed primarily in B lymphocytes. It binds to several regions within the murine immunoglobulin heavy chain locus, and has been associated with increases in immunoglobulin RNA levels. Bright expression and DNA-binding activity can be induced in normal adult spleen screens by a number of stimuli. Recent studies showed that stimulated lymphocytes from xid mice did not produce Bright DNA-binding activity; even though Bright protein was not present. Other experiments suggest that Bright and BTK interact directly in normal mice. Thus, Bright activity may require a functional BTK. The proposed studies will address the hypothesis that defective BTK leads to inactive forms of Bright that might at least partially explain the low serum immunoglobulin levels observed in xid, and by extension, XLA. The specific aims are. 1) to investigate the importance of BTK for Bright DNA- binding activity by co-expression, immunoprecipitation, and identification of post-translational modifications, 2) to determine if functional Bright is present in B cells from XLA patients using mobility shift assays, 3) to determine the relationship of Bright to the xid phenotype by producing dominant negative forms of Bright and expressing then in transgenic mice, 4) to determine how Bright functions in the immunoglobulin locus using in vitro transcription and topoisomerase assays, and 5) to identify additional genes potentially regulated by Bright interactions by mobility shift assay and antibody facilitated cloning. These studies will provide important new insights into Bright's potential role in xid and the human immunodeficiency disease, XLA, and will contribute to our understanding of immunoglobulin gene regulation.