The NF-kB Target, Gadd45Beta, in Lymphocytes and Liver

描述（由申请人提供）：除了组织免疫和炎症反应外，NF-κ B还控制细胞存活。这种控制对于B淋巴细胞生成、T细胞稳态、肿瘤发生和拮抗TNF α诱导的杀伤至关重要。关于TNF α，NF-κ B抗凋亡活性涉及抑制JNK信号传导。使用无偏筛选，我们已经确定Gadd 45 β/Myd 118作为这种抑制的关键介质，并发现其活性取决于JNK激酶MKK 7/JNKK 2的直接阻断。Gadd 45 β是CD 4 + T细胞应答和肝脏保护免受外部挑战所必需的-这两个过程部分由JNK和NF-κ B控制。然而，Gadd 45 β调节T淋巴细胞功能的机制以及这种调节与体内适应性免疫的相关性尚不清楚。同样，Gadd 45 β在肝脏对损伤的反应中的确切作用仍有待确定。该提案有三个具体目标，将同时解决这些问题。在目标1中，通过使用体内方法，我们将确定Gadd 45 β的生理功能，以及其在T细胞稳态和适应性免疫应答中对MAPK信号传导的控制。我们将开始通过检查在对抗原的生理反应期间Gadd 45 β-/- T细胞池的扩张和收缩的动力学。Gadd 45 β抗凋亡活性与外周T细胞缺失和记忆T细胞发育的相关性将使用充分表征的模型来建立。在目标2中，我们将评估在生理抗原引发期间，离体Gadd 45 β控制T细胞功能的基础。使用该系统，我们将建立Gadd 45 β消融对T细胞活化、增殖、TH 1/TH 2分化和AICD的精确影响。Gadd 45 β对TCR诱导的MAPK通路的影响及其对T细胞功能的影响将被具体检查。在目标3中，我们将使用已建立的TNFa诱导的JNK介导的肝毒性模型，确定Gadd 45 β在肝脏对损伤的反应中的作用的基础。特别是，我们将建立JNK信号转导的Gadd 45 β控制与肝脏中NF-κ B保护功能的相关性。还将在不存在任何基质或生物体影响的情况下，在体外研究肝细胞功能。总而言之，这些研究可能为自身免疫，慢性炎症和癌症的机制提供重要的新见解，也许还可以为其治疗提供新的治疗工具。

DESCRIPTION (provided by applicant): In addition to marshalling immune and inflammatory responses, NF-kappaB controls cell survival. This control is crucial to B lymphopoiesis, T cell homeostasis, oncogenesis, and to antagonize TNFalpha-induced killing. With regard to TNFalpha the NF-kappaB anti-apoptotic activity involves the suppression of JNK signaling. Using an unbiased screen, we have identified Gadd45beta/Myd118 as a pivotal mediator of this suppression, and have found that its activity depends on direct blockade of the JNK kinase, MKK7/JNKK2. Gadd45beta is required for CD4+ T cell responses and hepato-protection from external challenge - two processes controlled in part by JNK and NF-kappaB. However, the mechanism(s) by which Gadd45beta regulates T lymphocyte function and the relevance of this regulation to adaptive immunity, in vivo, are not known. Likewise, the precise role of Gadd45beta in the liver response to injury remain to be determined. This proposal has three Specific Aims, which will address these issues concurrently. In Aim 1, by using an in vivo approach, we will determine the physiologic function of Gadd45beta, and its control of MAPK signaling, in T cell homeostasis and adaptive immune responses. We will begin by examining kinetics of expansion and contraction of the Gadd45beta-/- T cell pool during a physiologic response to antigen. The relevance of the Gadd45beta anti-apoptotic activity to peripheral T cell deletion and memory T cell development will be established using well-characterized models. In Aim 2, we will assess the basis for the Gadd45beta control of T cell function, during physiologic antigen-priming, ex vivo. Using this system, we will establish the precise effects of Gadd45beta ablation on T cell activation, proliferation, TH1/TH2 differentiation, and AICD. The impact of Gadd45beta on TCR-induced MAPK pathways and its consequences on T cell function will be specifically examined. In Aim 3, we will determine the bases for the role of Gadd45beta in the liver response to injury, using well-established models of TNFalpha-induced, JNK-mediated hepato-toxicity. In particular, we will establish the relevance of the Gadd45beta control of JNK signaling to the NF-kappaB protective function in the liver. Hepatocyte function will be also studied in vitro, in the absence of any stromal or organismal influences. Altogether, these studies may provide important new insights into mechanisms of autoimmunity, chronic inflammation, and cancer, and perhaps, new therapeutic tools for their treatments.