Molecular Mechanisms of HCO3- Secretion by the Pancreatic Duct

胰管分泌 HCO3- 的分子机制

• 批准号: 7464514
• 负责人: Shmuel Muallem
• 金额: $ 34.02万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-05 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7464514
• 关键词: Affect; Bicarbonates; Biological Models; Coupled; Cyclic AMP-Dependent Protein Kinases; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Data; Disease; Duct (organ) structure; Ductal; Electrolytes; Enzyme Activation; Enzymes; Epithelial; Etiology; Family; Fluids and Secretions; Gland; Health; In Vitro; Intestines; Link; Liquid substance; Mediating; Membrane Potentials; Molecular; Mus; Mutation; Pancreas; Pancreatic duct; Pancreatitis; Pathway interactions; Phosphorylation; Phosphorylation Site; Phosphotransferases; Protein Isoforms; Regulation; Rest; Role; Signal Pathway; Site; Small Interfering RNA; Structure; Surface; Testing; Time; Work; absorption; acute pancreatitis; base; basolateral membrane; chronic pancreatitis; in vivo; luminal membrane; member; mutant; pancreatic juice; premature; prevent; public health relevance; stoichiometry; upstream kinase

DESCRIPTION (provided by applicant): Fluid and electrolyte transport by the pancreatic duct is unique among secretory glands. The duct does not absorb Na and secrets nearly 140 mM HCO3-. Ductal function is critical for pancreatic health, as evident in CF and pancreatitis. Although the Cl function of CFTR is required for ductal secretion, recent findings show that CFTR is a global regulator of epithelial function by regulating several Cl- and HCO3- transporters that participate in duntal fluid and HCO3- secretion, in particular members of the SLC26 transporters family (SLC26Ts). Indeed, we have shown that a) the electrogenicity and isoform specific stoichiometry of the SLC26Ts, b) the function of the SLC26Ts in ductal HCO3- secretion, c) the mutual regulation of the SLCTs and CFTR, d) the interaction between the CFTR R domain and SLC26Ts STAS domain, e) the regulation of the SLC26Ts by the WNKs kinases. These findings led to a new hypothesis of ductal fluid and HCO3- secretion in which the bulk of HCO3- secretion is mediated by different SLC26Ts that are regulated by CFTR. In turn, the SLC26Ts supress CFTR activity in the resting state and enhance CFTR activity at the stimulated state. CFTR determines the final HCO3- concentration in the pancreatic juice by controlling the membrane potential of the duct. We will test this hypothesis in model systems and native pancreatic ducts of WT and slc26a6-/- mice and the role of HCO3- secretion in pancreatitis in four specific aims: 1. Determine the role of coserved Ser/Thr/Tyr phosphortlation sites suggested by the NMR structure od STAS-R domains in the STAS-R domain interaction and mutual regulation of CFTR and slc26a3/6. 2. Study regulation of slc26a3/6 by the WNKs kinases and in the reciprocal regulation of CFTR and slc26a3/6 in vitro and in vivo. 3. study the role of kinases and signaling pathways upstream of the WNKs and kinases downstrean of the WNKs in the regulation of slc26a3/6 in vivtro and in vivo. 4. Examine the role of slc6a6 and HCO3- secretion in pancreatitis. The slc26a6-/- mice in which HCO3- secretion is compromized, will be used to determine the role of HCO3- secretion in induction and progression of acute pancreatitis. The proposed work should advance our understanding of pancreatic duct fluid and HCO3- secretion and result in information relevant to pancreatitis and Cystic Fibrosis. Public Health Relevance: The pancreas secretes digestive enzymes and fluid that contains a lot of HCO3- that wash the enzymes to the intestine. The HCO3- is needed to prevent premature activation of the enzymes so that they will not digest the pancreas itself. When HCO3- secretion is aberrant the pancreas digests itself as occur in the diseases Cystic Fibrosis and pancreatitis. This work is aimed to understand how the pancreas secretes HCO3- and why HCO3- secretion is aberrant in pancreatitis and Cystic Fibrosis.

描述（由申请人提供）：胰管的液体和电解质转运在分泌腺中是独特的。导管不吸收Na，并分泌近140 mM HCO 3-。导管功能对胰腺健康至关重要，如CF和胰腺炎所示。尽管CFTR的Cl功能是导管分泌所必需的，但最近的研究结果表明，CFTR是上皮功能的全局调节剂，其通过调节参与牙垢液和HCO 3-分泌的几种Cl-和HCO 3-转运蛋白，特别是SLC 26转运蛋白家族（SLC 26 Ts）的成员。事实上，我们已经表明a）SLC 26 Ts的产电性和同种型特异性化学计量，B）SLC 26 Ts在导管HCO 3-分泌中的功能，c）SLCT和CFTR的相互调节，d）CFTR R结构域和SLC 26 Ts STAS结构域之间的相互作用，e）WNK激酶对SLC 26 Ts的调节。这些发现导致了导管液和HCO 3-分泌的新假设，其中大部分HCO 3-分泌由CFTR调节的不同SLC 26 T介导。反过来，SLC 26 T在静息状态下抑制CFTR活性并在刺激状态下增强CFTR活性。CFTR通过控制导管的膜电位来确定胰液中的最终HCO 3浓度。我们将在WT和slc 26 a6-/-小鼠的模型系统和天然胰管中检验这一假设，并在四个具体目标中检验HCO 3分泌在胰腺炎中的作用：1.确定STAS-R结构域的NMR结构所提示的保守的Ser/Thr/Tyr磷酸化位点在STAS-R结构域相互作用以及CFTR和slc 26 a3/6的相互调节中的作用。2.研究WNK激酶对slc 26 a3/6的调节以及CFTR和slc 26 a3/6在体外和体内的相互调节。3.研究WNK上游激酶和信号通路及下游激酶在体内外slc 26 a 3/6调控中的作用。4.检查slc 6a 6和HCO 3-分泌在胰腺炎中的作用。HCO 3分泌受损的slc 26 a6-/-小鼠将用于确定HCO 3分泌在急性胰腺炎诱导和进展中的作用。这项工作将促进我们对胰管液和HCO 3-分泌的理解，并产生与胰腺炎和囊性纤维化相关的信息。 公共卫生相关性：胰腺分泌消化酶和含有大量HCO 3的液体-将酶冲洗到肠道。需要HCO 3-来防止酶的过早激活，这样它们就不会消化胰腺本身。当HCO 3-分泌异常时，胰腺会自行收缩，如囊性纤维化和胰腺炎。这项工作旨在了解胰腺如何分泌HCO 3-以及为什么HCO 3-分泌在胰腺炎和囊性纤维化中异常。