RECEPTORS FOR CCK AND OTHER GI HORMONES

描述：（改编自申请人的摘要）：本修订申请 旨在了解胰腺腺泡细胞之间的相互作用， 蛙皮素（Bn）和胆囊收缩素（CCKA）或胃泌素（CCKB）受体。 胰腺腺泡细胞对于食物的消化是至关重要的，并且参与 病理状态包括胰腺炎和胰腺癌。Bn和CCK 受体调节腺泡细胞功能，并且其自身由腺泡细胞调节。 细胞机制Bn和Bn的分子机制和结构特征 影响腺泡细胞功能的CCK受体尚未确定。的 该建议的第一个具体目标是确定 Bn、CCKA和CCKB偶联至胰腺腺泡生物学特性的差异 功能和细胞信号传导。Bn、CCKA和CCKB受体的功能 将在腺泡细胞中比较来自人类和啮齿动物的细胞。为此目的， 基因转移技术、基于腺病毒的载体或转基因 动物，将被雇用。在腺泡中表达这些受体的影响 细胞对受体偶联的生物反应，包括分泌， 蛋白质合成，炎症介质的产生，以及 将检查与这些响应中的每一个相关联的信号传导机制。 这些研究将允许第一次直接比较不同受体之间的差异。 在腺泡细胞环境中来自不同物种的亚型和受体。 突变受体将用于确定受体的结构基础 偶合器.第二个具体目标是确定细胞机制， 参与胰腺癌细胞受体运输的受体结构特征 腺泡细胞关于CCKB或Bn受体的运输， 胰腺腺泡细胞CCKA受体固定在腺泡细胞上 通过激动剂占据表面，但不内化。这个图案很独特 因为这些受体在成纤维细胞模型中被内化。 人和啮齿动物CKB和Bn受体的运输特性将 在胰腺腺泡细胞中使用生物化学和成像进行检查 技术.然后，研究了受体中特定结构域和位点的作用， 贩运将受到审查。此外，分子的子集在 受体运输将探讨，包括G蛋白偶联受体 激酶（GRKs）和抑制蛋白，在胰腺腺泡细胞从人类和小鼠。 过表达相关亚型对受体转运的影响 这些分子和它们的主要负对应物，或反义 将对结构进行检查。第三个具体目标将决定细胞 受体参与的机制和受体结构特征 胰腺腺泡细胞的脱敏。很少有人知道的 脱敏特征或分子机制参与的 Bn或CCK受体的脱敏。的脱敏特性 不同的受体将在胰腺腺泡细胞生物学上被定义 反应和细胞信号。突变受体将被用来确定 受体脱敏的结构基础。此外， 将在腺泡上检查操纵GRKs和抑制蛋白对脱敏的影响。 细胞生物学反应和相关的细胞内信号。综合这些 研究将提供重要的洞察机制调节 胰腺腺泡细胞功能。

DESCRIPTION: (Adapted from the Applicant's Abstract): This revised application seeks to understand the interactions between pancreatic acinar cells and receptors for bombesin (Bn) and cholecystokinin (CCKA) or gastrin (CCKB). Pancreatic acinar cells are critical for digestion of food and are involved in pathological states including pancreatitis and pancreatic cancer. Bn and CCK receptors regulate acinar cell function and are themselves regulated by acinar cell mechanisms. The molecular mechanisms and the structural features of Bn and CCK receptors that influence acinar cell function have not been identified. The first specific aim of this proposal is to determine the molecular basis for differences in Bn, CCKA, and CCKB coupling to pancreatic acinar biological functions and cell signaling. The functioning of Bn, CCKA, and CCKB receptors from humans and rodents will be compared in acinar cells. For this purpose, gene transfer techniques, wither adenoviral-based vectors or transgenic animals, will be employed. The effects of expressing those receptors in acinar cells on receptor coupling to biological responses, including secretion, protein synthesis, and the generation of inflammatory mediators, and the signaling mechanisms associated with each of those responses will be examined. These studies will allow the first direct comparison between different receptor subtypes and receptors from different species in an acinar cell environment. Mutant receptors will be utilized to determine the structural basis of receptor coupling. The second specific aim is to determine the cellular mechanisms and receptor structural features involved in receptor trafficking in pancreatic acinar cells. Nothing is known concerning CCKB or Bn receptor trafficking in pancreatic acinar cells. CCKA receptors are immobilized on the acinar cell surface by agonist occupation but are not internalized. This pattern is unique to the acinar cell as these receptors are internalized in fibroblast models. The trafficking characteristics of human and rodent CKB and Bn receptors will be examined in pancreatic acinar cells employing biochemical and imaging techniques. Then, the role of specific domains and sites in receptor trafficking will be examined. Also, the subset of molecules important in receptor trafficking will be explored, including G protein-coupled receptor kinases (GRKs) and arrestins, in pancreatic acinar cells from humans and mice. The effects on receptor trafficking of over-expressing the relevant isoforms of these molecules and their dominant negative counterparts, or anti-sense constructs will be examined. The third specific aim will determine the cellular mechanisms and receptor structural features involved in receptor desensitization in pancreatic acinar cells. Little is known about the desensitization characteristics or molecular mechanisms involved in the desensitization of Bn or CCK receptors. The desensitization characteristics of the different receptors will be defined on pancreatic acinar cell biological responses and cell signals. Mutant receptors will be employed to determine the structural basis for receptor desensitization. Also, the effects of manipulating GRKs and arrestins on desensitization will be examined on acinar cell biological responses and associated intracellular signals. Together these studies will provide important insights into the mechanisms regulating pancreatic acinar cell function.