Dietary Regulation of Pancreatic Digestive Enzymes

描述(由申请人提供)：这项工作的总体目标是了解成人胰腺的生长是如何调节的，以提供足够的消化酶供应。我们假设增长可以通过两种机制发生。第一种是对饮食和激素的反应，涉及刺激分化的腺泡细胞进入细胞周期和分裂。在组织损伤后发生的第二种生长形式，如胰腺炎，涉及去分化、细胞分裂和去分化，将被称为再生。我们的荷尔蒙刺激生长的主要模型包括给小鼠喂食合成蛋白酶抑制剂卡莫司坦以增加血浆CCK。我们已经证明，这种生长需要钙激活的磷酸酶钙调神经磷酸酶和mTOR途径，并伴随着MAP激酶、ERK和JNK的激活，以及包括多个c-jun和c-Fos家族成员在内的许多早期反应基因的表达。在特定的目标1中，我们将研究慢性CCK升高驱动的分化细胞有丝分裂和生长的调节机制。A)我们将确定CCK激活的细胞周期调节因子。B)我们将研究由NFATs(由钙调神经磷酸酶调节)和AP-1(由MAP激酶激活)调控的靶基因，特别是对细胞周期调节基因如细胞周期蛋白D1和增殖细胞核抗原的调节，以及对钙调神经磷酸酶的内源性反馈抑制物如MClP1。在特定的目标2中，我们将确定组织损伤后介导再生的机制。我们将研究乙硫氨酸和雨蛙素过度刺激诱导的两种胰腺炎模型后的再生。A)我们将利用CCK缺陷小鼠确定在CCK存在和不存在的情况下，基因表达模式在再生过程中是如何改变的。B)我们将使用药物抑制剂和基因靶向小鼠来确定钙调神经磷酸酶和mTOR对再生的重要性。在特定的目标3中，我们将确定CCK和生长因子刺激的腺泡细胞在原代单层培养中的生长调节机制。原代单层培养是一种类似于再生的生长模型，其中蛋白质和siRNA可以用腺病毒载体表达。我们将首先确定去分化的特征，并通过谱系追踪建立分裂细胞的腺泡细胞起源。然后，我们将评估不同的信号通路和细胞周期成分的重要性，重点是c-jun和AP1的关键作用。总体而言，该项目将有助于更好地了解胰腺生长，并有助于设计调节人类胰腺生长的方法。与公共卫生相关：许多胰腺疾病，包括急性和慢性胰腺炎以及胰腺癌，都会导致胰腺组织功能丧失。来自该项目的知识应该能够设计方法来帮助人类胰腺再生，并确保足够的胰腺消化酶供应。

DESCRIPTION (provided by applicant): The overall aim of this work is to understand how the growth of the adult pancreas is regulated to provide an adequate supply of digestive enzymes. We hypothesize that growth can occur by two mechanisms. The first occurs in response to diet and hormones and involves stimulation of differentiated acinar cells to enter the cell cycle and divide. The second form of growth that occurs following tissue injury such as pancreatitis involves dedifferentiation, cell division and dedifferentiation and will be referred to as regeneration. Our primary model for hormonal stimulation of growth involves feeding the synthetic protease inhibitor, camostat to mice to increase plasma CCK. We have shown this growth requires the calcium activated phosphates calcineurin and the mTOR pathway, and is accompanied by the activation of the MAP kinases, ERK and JNK, and the expression of a number of early response genes including multiple c-Jun and c-Fos family members. In Specific Aim 1 we will study the mechanisms mediating mitogenesis and growth of differentiated cells driven by chronic CCK elevation. a) We will identify the cell cycle regulators activated by CCK. b) We will study target genes regulated by NFATs (regulated by calcineurin) and AP-1 (activated by MAP kinases) with particular attention to regulation of cell-cycle regulating genes such as cyclin D1 and PCNA and to endogenous feedback inhibitors such as MClP1 for calcineurin. In Specific Aim 2 we will determine the mechanisms mediating regeneration after tissue injury. We will study regeneration following two models of pancreatitis induced by ethionine and caerulein over-stimulation. a) We will determine how the pattern of gene expression is altered in regeneration in the presence and absence of CCK using CCK deficient mice. b) We will determine the importance of calcineurin and mTOR for regeneration using both pharmacological inhibitors and gene targeted mice. In Specific Aim 3 we will determine the regulatory mechanisms for CCK and Growth Factor stimulated growth of acinar cells in primary monolayer culture which serves as a model for growth similar to regeneration and in which proteins and siRNA can be expressed with adenoviral vectors. We will first characterize the dedifferentiation and establish the acinar cell origin of dividing cells by lineage tracing. We will then evaluate the importance of different signaling pathways and cell cycle components with a focus on the key role of c-jun and AP1. Overall, the project will lead to better understanding of pancreatic growth and assist in designing approaches to regulating pancreatic growth in humans. PUBLIC HEALTH RELEVANCE: A number of pancreatic diseases including acute and chronic pancreatitis and pancreatic cancer lead to a loss of functioning pancreatic tissue. Knowledge from this project should allow designing approaches to assist the human pancreas to regenerate and ensure an adequate supply of pancreatic digestive enzymes.