Molecular Pathomechanism of Hereditary Pancreatitis

描述(由申请人提供)：这项赠款提案的广泛的、长期的目标是利用遗传性胰腺炎和其他形式的遗传决定的胰腺炎作为生化模型来了解人类胰腺炎的分子机制。遗传性胰腺炎中最常见的突变影响到编码人类阳离子胰酶原的PRSS1基因和编码胰腺分泌性胰蛋白酶抑制物的SPINK1基因。在之前的资助期间，我们的实验室已经开发了体外研究人类胰酶原突变的方法，并通过对几个与胰腺炎相关的突变的表征，形成了一个工作假说。该模型认为腺泡内胰酶活性升高是遗传性胰腺炎的基本启动步骤，而胰酶原突变通常通过增加自身催化激活来发挥这一作用。在目前的提案中，我们试图扩展我们的机制模型，并证明胰酶活性增加在所有形式的遗传性胰腺炎中起核心作用。将研究以下具体目标。(1)人肠系膜胰蛋白酶在胰腺炎中的作用。中胰酶是一种专用于降解胰酶抑制剂的独特的蛋白酶。过早激活中胰蛋白酶原可能降低胰腺保护性SPINK1水平，参与胰腺炎的发病过程。(2)胰腺炎相关阳离子胰蛋白酶原(PRSS1)突变体的特性。识别新的依赖突变的生化缺陷将使我们能够完善我们的分子发病模型。(3)保护胰腺炎的新型阴离子胰蛋白酶原(PRSS2)突变体的功能分析功能丧失的胰酶原突变可以预防胰腺炎，这一概念为胰酶在这种疾病中的中心作用提供了独立的证据。(4)胰腺炎相关SPINK1突变体致病生化缺陷的鉴定。

DESCRIPTION (provided by applicant): The broad, long-term objectives of this grant-proposal are to understand the molecular mechanisms of human pancreatitis using hereditary pancreatitis and other forms of genetically determined pancreatitis as biochemical models. The most frequently found mutations in genetic pancreatitis affect the PRSS1 gene that codes for human cationic trypsinogen and the SPINK1 gene encoding pancreatic secretory trypsin inhibitor. In the previous funding period our laboratory has developed methodology for the in vitro study of human trypsinogen mutations and through characterization of several pancreatitis-associated mutants we have formulated a working hypothesis. This model states that elevated intraacinar trypsin activity is the fundamental initiating step of genetic pancreatitis and trypsinogen mutations generally exert this effect through increased autocatalytic activation. In the present proposal we seek to extend our mechanistic model, and prove that increased trypsin activity plays the central role in all forms of genetic pancreatitis. The following specific aims will be studied. (1) The role of human mesotrypsin in pancreatitis. Mesotrypsin is a unique protease specialized for the degradation of trypsin inhibitors. Premature mesotrypsinogen activation might lower protective SPINK1 levels in the pancreas and contribute to the pathogenesis of pancreatitis. (2) Characterization of pancreatitis-associated cationic trypsinogen (PRSS1) mutants. Identification of novel mutation-dependent biochemical defects will allow us to refine our model of molecular pathogenesis. (3) Functional analysis of novel anionic trypsinogen (PRSS2) mutants that afford protection against pancreatitis. The concept that loss-of-function trypsinogen mutations can protect against pancreatitis provides independent evidence for the central role of trypsin in this disease. (4) Identification of the disease-causing biochemical defects in pancreatitis-associated SPINK1 mutants.