REGULATION OF NF-KAPPA B

生物的生长、分化和发育受到转录因子时空调控的严格控制。nf - κ b蛋白是一个转录因子大家族，它控制着大量基因的表达，这些基因参与免疫反应、癌症、病毒感染、程序性细胞死亡、发育线索等。与大多数转录因子不同，NF-kappaB蛋白与抑制蛋白（IkappaBs）一起被隔离在细胞质中。作为对外部信号的响应，IkappaB蛋白被蛋白体磷酸化、泛素化和降解，从而允许NF-kappaB蛋白释放到细胞核，在细胞核中它们可以结合到同源DNA结合位点并激活特定基因的转录。NF-kappaB蛋白响应外源刺激激活的重要事件是IkappaB蛋白的降解。在这个提案中，我们计划研究一个大的细胞质复合体的组成部分，称为IKK，它接收信号并调节IkappaB蛋白的降解。我们计划了解IKK复合体中存在的IKK1和IKK2这两种激酶的分子功能，因为它们在独特的残基上磷酸化IkappaBalpha，从而触发其降解过程。我们已经产生了两种激酶被单独或同时基因删除的小鼠。这些激酶对小鼠发育的显著但截然不同的影响使我们想知道这些激酶在生长发育中是否具有明显不同的作用。我们计划研究双“敲除”小鼠（IKK1和IKK2均被去除）脑畸形的性质和机制。我们还将研究这些激酶在不同组织中对哪些特定的信号通路作出反应。通过使用新的DNA微阵列技术（可以同时分析数千个基因），我们将鉴定NF-kappaB蛋白诱导的细胞生长和程序性细胞死亡（凋亡）的新基因。我们还计划确定这两种激酶是否参与诱导IkappaB蛋白磷酸化的其他功能。最后，我们还建议生成含有IKKs或IkappaB蛋白突变形式的病毒载体，并研究它们对哮喘、类风湿关节炎、癌症模型（辐射损伤、化学毒物）和发育等实验模型系统的影响。我们相信这里提出的实验将使我们能够破译NF-kappaB蛋白调控的分子机制。对这一重要信号通路的详细了解将使我们能够制定治疗从炎症到癌症等疾病的策略。

Growth, differentiation, and development of an organism is tightly controlled by the spatial and temporal regulation of transcription factors. NF-kappaB proteins are a large family of transcription factors which control the expression of a vast array of genes involved in immune response, cancer, viral infections, programmed cell death, developmental clues, etc. Unlike most transcription factors, NF-kappaB proteins are sequestered in the cytoplasm in association with inhibitory proteins (IkappaBs). In response to an external signal, the IkappaB proteins are phosphorylated, ubiquitinated, and degraded by proteosomes to allow the release of the NF-kappaB protein to the nucleus where they can bind to the cognate DNA binding sites and activate transcription of specific genes. The seminal event in the activation of NF-kappaB proteins in response to exogenous stimulus is the degradation of IkappaB proteins. In this proposal we are planning to study the components of a large cytoplasmic complex, referred to as IKK, which receives the signal and modulates the degradation of IkappaB protein. We plan to understand the molecular function of the two kinases, IKK1 and IKK2 present in the IKK complex because they phosphorylate IkappaBalpha at unique residues to trigger its degradation process. We have generated mice where the two kinases have been genetically deleted either singly or both of them. The remarkable but quite distinct influences of these kinases on mice development lead us to ask if these kinases have distinctly different roles in growth and development. We plan to study the nature and mechanism of brain malformation in double "knockout" mice (both IKK1 and IKK2 are removed). We will also study what specific signal pathways each of these kinases respond to in different tissues. By using novel DNA microarray technology (thousands of genes can be analyzed simultaneously) we will identify novel genes induced by NF-kappaB proteins in cell growth and programmed cell death (apoptosis). We also plan to determine if the two kinases are involved in functions other that induced phosphorylation of IkappaB proteins. Finally, we also propose to generate viral vectors containing mutant forms of IKKs or IkappaB proteins and study their effect on experimental model systems like asthma, rheumatoid arthritis, cancer models (radiation damage, chemotoxic agents), and development. We believe that the experiments proposed here will allow us to decipher the molecular mechanism of regulation of NF-kappaB proteins. The detailed knowledge of this important signal pathway will allow us to develop strategies for curing diseases ranging from inflammation to cancer.