ACID-BASE INTERACTIONS IN PANCREATIC FUNCTION & DISEASE

胰腺功能中的酸碱相互作用

• 批准号: 2137202
• 负责人: GEORGE A SCHEELE
• 金额: $ 23.42万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-05-01 至 1995-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2137202
• 关键词: Golgi apparatus; acidity /alkalinity; acinar cell; dogs; embryonic stem cell; genetically modified animals; granule; intracellular membranes; intracellular transport; laboratory mouse; membrane activity; pancreas; proteoglycan; secretion; zymogens

This grant will investigate the role of acid-base interactions in the regulated storage and release of granule contents in pancreatic acinar cells. We will test the hypothesis that formation of GP2 tetramers in the acidic milieu of the trans-Golgi network (TCN) organizes a GP2/proteoglycan (PG) matrix tightly associated with the lumenal surface of zymogen granule (ZG) membranes and that this matrix functions in (a) membrane sorting during granule assembly in the TCN, (b) inactivation of ZG membranes during the storage phase of secretion, and (c) regulated trafficking of ZG membranes from the apical plasma membrane (APM) after exocytosis. Since the acidic pH of the TGN plays a critical role in condensation of secretory proteins, alkalinization of the acinar lumen appears to be required for (i) neutralization of the acidic pH of exocytic contents and (ii) solubilization of aggregated (pro)enzymes. We will determine if alkalinization of the acinar lumen leads to the release of the GP2/PG matrix from the APM and if pH-dependent matrix removal regulates internalization of ZG membranes for reuse during the secretory process. Taken together, our preliminary findings suggest that lumenal factors including acid-base interactions and matrix assembly and disassembly processes perform critical functions during regulated storage and release of pancreatic enzymes. Definitive analysis of GP2 function in regulated pancreatic secretion will be made by constructing a GP2 null mutation in J1 embryonic stem cells and introducing this trait into the germ line of transgenic mice. Analysis of zymogen granule structure and function and regulated secretory performance in normal and mutant mice will allow us to confirm the cellular function(s) of GP2, the major glycoprotein in ZG membranes. These studies can be expected to provide valuable information concerning a recently described gene family (GP2/THP), which encodes a new class of GPI-anchored proteins targeted to intracellular secretory compartments in polarized epithelial cells. A detailed understanding of lumenal processes including acid-base interactions and matrix assembly and disassembly processes in trafficking of ZG membranes at the APM provides, for the first time, important insights into pancreatic dysfunctions observed in these processes (dramatic loss of zymogen granules and marked dilatation of the acinar lumen) in patients with cystic fibrosis.

该赠款将研究酸碱相互作用在 胰腺粉刺中颗粒内容物的调节储存和释放 细胞。 我们将检验以下假设：GP2四聚体在 Trans-Golgi网络（TCN）的酸性环境组织 GP2/proteoglycan（PG）基质与腔表紧密相关 Zymogen颗粒（ZG）膜的膜，该基质在（a）中起作用 TCN中颗粒组件期间的膜分类，（b）灭活 ZG膜在分泌的存储阶段，（c）调节 从顶端质膜（APM）贩运ZG膜之后 胞吞作用。 由于TGN的酸性pH在 分泌蛋白的凝结，腺泡腔的碱化 似乎需要（i）外生细胞中和酸性pH 含量和（ii）聚集（Pro）酶的溶解化。 我们将 确定腺泡管腔的碱化是否导致释放 来自APM的GP2/PG矩阵，如果pH依赖性矩阵去除 调节ZG膜的内在化，以便在分泌过程中重复使用 过程。 综上所述，我们的初步发现表明Lumenal 包括酸碱相互作用和基质组件以及 拆卸过程在调节存储期间执行关键功能 并释放胰腺酶。 GP2功能的确定分析 通过构建gp2 null进行调节的胰腺分泌物 J1胚胎干细胞中的突变，并将该性状引入 转基因小鼠的生殖系。 酶原颗粒结构和 正常小鼠和突变小鼠的功能和调节分泌性能 将允许我们确认GP2的细胞函数，主要 ZG膜中的糖蛋白。 可以期望这些研究提供 有关最近描述的基因家族的宝贵信息 （gp2/thp），它编码针对针对的新的GPI锚定蛋白 极化上皮细胞中的细胞内分泌室。 一个 详细了解包括酸碱在内的流体过程 交互和矩阵组装和拆卸过程 APM处的ZG膜的首次提供 对这些过程中观察到的胰腺功能障碍的见解 （酶原颗粒的戏剧性损失和腺泡的明显扩张 Lumen）患有囊性纤维化患者。