Proteotoxicity in the Pathophysiology of Chronic Pancreatitis

描述（由申请人提供）：胰腺炎是一种炎症性疾病，具有重大的健康和经济负担，缺乏既定的治疗方法来预防复发发作或进展为慢性疾病。我们的长期目标是开发治疗这些疾病的方法。缺乏有效的治疗方法部分源于我们对胰腺炎病理生理学的有限理解。目前流行的胰蛋白酶依赖模型认为，细胞内胰蛋白酶原激活和导致胰蛋白酶失活的保护机制失效是发病的核心。尽管付出了巨大的努力，胰蛋白酶在胰腺炎中的作用仍然是推测性的和不完全确定的。最近的研究提出了外分泌蛋白突变、正常蛋白稳态破坏和内质网超载途径激活的另一种发病机制。结果，突变蛋白的表达对腺泡细胞是有毒的，增加了胰腺炎的风险。有了这个模型，开发新疗法的方法将与基于胰蛋白酶依赖模型的方法有很大不同。在此，我们提出了与慢性胰腺炎相关的羧基酯脂肪酶（CEL）突变激活适应性细胞信号通路和细胞死亡通路，启动炎症反应并增加细胞对代谢应激损伤的易感性的假设。CEL突变发生在含有可变数量的富含脯氨酸串联重复序列（VNTR）的区域。我们的初步数据表明，DEL变异体在细胞内聚集并激活适应性细胞信号通路。我们提出以下具体目标：1)确定CEL VNTR变体不溶性聚集体处置的细胞途径；2)确定CEL VNTR变体表达激活的适应性细胞信号通路；3)在胰腺中表达CEL VNTR变体的小鼠模型中证实我们的离体结果。拟议的研究所获得的知识将提高对胰腺损伤的整体理解，并为针对新的治疗靶点蛋白质稳态的潜在药物干预提供见解。

DESCRIPTION (provided by applicant): Pancreatitis is an inflammatory disease with significant health and economic burdens that lacks an established therapy to prevent recurrent episodes or progression to chronic disease. Our long-term goal is to develop therapies for these diseases. The absence of effective therapies stems in part from our limited understanding about the pathophysiology of pancreatitis. The prevailing trypsin-dependent model holds that intracellular trypsinogen activation and failure of protective mechanisms responsible for trypsin inactivation are central to pathogenesis. Despite great effort the role of trypsin in pancreatitis remains speculative and incompletely defined. Recent studies suggest another mechanism for disease in patients with mutations in exocrine proteins, disruption of normal protein homeostasis and activation of ER overload pathways. As a result, expression of the mutant proteins is toxic to acinar cells and increases the risk for pancreatitis. With this model, the approach to developing new therapeutics would differ significantly from approaches based on the trypsin-dependent model. Herein, we address the hypothesis that carboxyl ester lipase (CEL) mutants associated with chronic pancreatitis activate adaptive cell signaling pathways and cell death pathways, initiate an inflammatory response and increase susceptibility of cells to injury by metabolic stress. The CEL mutations occur in the region containing a variable number of proline-rich tandem repeats (VNTR). Our preliminary data show that the DEL variants accumulate within the cells as aggregates and activate adaptive cell signaling pathways. We propose the following Specific Aims: 1) Determine the cellular pathways for the disposal of insoluble aggregates of CEL VNTR variants; 2) Identify the adaptive cell signaling pathways activated by expression of CEL VNTR variants; 3) Confirm our ex vivo results in mouse models that express CEL VNTR variants in the pancreas. The knowledge gained by the proposed studies will improve the overall understanding of pancreatic injury and provide insight into potential pharmacological interventions directed at a new therapeutic target, protein homeostasis.