Molecular Mechanisms of Acute Pancreatitis

描述(由申请人提供)：胰腺炎与严重的发病率和死亡率有关。不幸的是，目前还没有治疗这种疾病的有效方法。这在很大程度上是因为决定这种疾病严重程度的分子机制仍然知之甚少。由于缺乏明确的动物模型，对这些机制的了解一直受到阻碍。在目前的方案中，我们将利用我们最近开发的新型转基因动物模型，该模型基于三苯氧胺调节的Cre重组酶的腺泡细胞特异性表达，该重组酶用于激活或删除直接调节胰腺炎严重程度的基因。这是第一个明确定义分子启动事件的胰腺炎动物模型。这项提议的总体目标是使用这些独特的模型来检验特定的机械论假说。特殊目的#1涉及核因子？B信号通路各组成部分的调节表达。尽管有很多证据表明核因子B是胰腺炎的关键介质，但关于其在疾病中的具体作用仍有许多重要的问题。我们将通过调节激活(p65/relA过度表达)或抑制(L？？-？)分子的表达，直接研究核因子？B的作用。删除还是I？B？核因子？B在胰腺腺泡细胞中特异表达。我们将测试几个关于腺泡细胞核因子B激活在炎症级联、腺泡细胞凋亡和坏死以及与急性胰腺炎相关的胰腺再生中的作用的机制假说。特异性目的#2是基于胰腺腺泡细胞中突变的活性K-ras(G12V)的调节表达。虽然激活的K-ras通常与胰腺癌有关，但我们观察到，在转基因动物胰腺内的腺泡细胞中，K-ras的表达导致腺泡细胞的急剧丧失和大量的纤维化，类似于人类慢性胰腺炎。我们将利用这个独特的动物模型来确定K-ras活性导致腺泡细胞损伤和影响星状细胞产生纤维化的具体分子机制。为了补充转基因小鼠的研究，并确保所研究的机制与人类疾病有关，我们还将进行体外研究，使用病毒载体在人和啮齿类腺泡细胞中表达基因。总之，这些研究将提供对急性胰腺炎机制的洞察，这在以前是不可能的，并可能导致改进的治疗方法。

DESCRIPTION (provided by applicant): Pancreatitis is associated with significant morbidity and mortality. Unfortunately, there are currently no effective therapies for this disease. This is largely because the molecular mechanisms that determine the severity of this disease remain poorly understood. Knowledge of these mechanisms has been hampered by the lack of well-defined animal models. In the current proposal, we will utilize novel transgenic animal models that we have recently developed based on acinar cell specific expression of a tamoxifen-regulated Cre recombinase that is used to activate or delete genes that directly regulate pancreatitis severity. These are the first animal models of pancreatitis in which the molecular initiating events are clearly defined. The overall aims of this proposal are to test specific mechanistic hypotheses using these unique models. Specific aim #1 involves the regulated expression of components of the NF?B signaling pathway. Despite much evidence that NF?B is a critical mediator of pancreatitis, many important questions remain about its specific actions in the disease. We will directly examine the role of NF?B by regulating the expression of molecules that will either activate (p65/relA over-expression) or inhibit (l??-? deletion or I?B? expression) NF?B specifically in pancreatic acinar cells. We will test several mechanistic hypotheses concerning the roles of acinar cell NF?B activation in the inflammatory cascade, acinar cell apoptosis and necrosis, and pancreatic regeneration associated with acute pancreatitis. Specific aim #2 is based on regulated expression of mutant active K-ras(G12V) in pancreatic acinar cells. While activated K-ras is generally associated with pancreatic cancer, we have observed that its expression in acinar cells within the pancreas of transgenic animals leads to a dramatic loss of acinar cells and abundant fibrosis resembling human chronic pancreatitis. We will utilize this unique animal model to identify the specific molecular mechanisms whereby K-ras activity causes acinar cell damage and influences stellate cells to produce fibrosis. To complement the studies in transgenic mice and to insure that the mechanisms being investigated are relevant to human disease, we will also conduct studies in vitro using viral vectors to express genes in human and rodent acinar cells. Together these studies will provide insights into the mechanisms of acute pancreatitis that have not previously been possible and which may lead to improved therapies.