Molecular Pathomechanism of Hereditary Pancreatitis

描述（由申请人提供）：本拨款提案的广泛、长期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，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编码人阳离子胰蛋白酶原的PRSS1基因和编码胰腺分泌型胰蛋白酶抑制剂的SPINK1基因。在之前的资助期内，我们的实验室已经开发了人类胰蛋白酶原突变的体外研究方法，通过对几种胰腺炎相关突变的表征，我们已经制定了一个工作假设。该模型表明，腺泡内胰蛋白酶活性升高是遗传性胰腺炎的基本起始步骤，胰蛋白酶原突变通常通过增加自催化激活来发挥这一作用。在目前的建议中，我们寻求扩展我们的机制模型，并证明胰蛋白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)人中胰蛋白酶在胰腺炎中的作用。中胰蛋白酶是一种独特的蛋白酶，专门用于降解胰蛋白酶抑制剂。过早的中胰蛋白酶原激活可能降低胰腺中的保护性SPINK1水平，并参与胰腺炎的发病机制。(2)胰腺炎相关阳离子胰蛋白酶原（PRSS1）突变体的特征。鉴定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机制模型。(3)新型阴离子胰蛋白酶原（PRSS2）突变体抗胰腺炎的功能分析。功能丧失胰蛋白酶原突变可以预防胰腺炎的概念为胰蛋白酶在这种疾病中的核心作用提供了独立的证据。(4)胰腺炎相关SPINK1突变体致病性生化缺陷的鉴定。

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.