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）：胰管输送液体和电解质的方式在分泌腺中是独一无二的。该导管不吸收 Na，并分泌近 140 mM HCO3-。导管功能对于胰腺健康至关重要，这在 CF 和胰腺炎中很明显。虽然 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 通过调节参与乳腺液和 HCO3- 分泌的多个 Cl- 和 HCO3- 转运蛋白，特别是 SLC26 转运蛋白的成员，从而成为上皮功能的全局调节剂。系列（SLC26T）。事实上，我们已经证明了 a) SLC26T 的电原性和亚型特异性化学计量，b) SLC26T 在导管 HCO3 分泌中的功能，c) SLCT 和 CFTR 的相互调节，d) CFTR R 之间的相互作用结构域和 SLC26Ts STAS 结构域，e) WNKs 激酶对 SLC26Ts 的调节。这些发现提出了导管液和 HCO3 分泌的新假说，其中大部分 HCO3 分泌是由受 CFTR 调节的不同 SLC26T 介导的。反过来，SLC26T 在静息状态下抑制 CFTR 活性，在刺激状态下增强 CFTR 活性。 CFTR 通过控制胰管的膜电位来确定胰液中最终的 HCO3- 浓度。我们将在 WT 和 slc26a6-/- 小鼠的模型系统和天然胰管中测试这一假设，并在四个具体目标中测试 HCO3- 分泌在胰腺炎中的作用： 1. 确定保守的 Ser/Thr/Tyr 磷酸化位点的作用STAS-R结构域的NMR结构，其中STAS-R结构域CFTR和slc26a3/6的相互作用和相互调节。 2. 研究 WNK 激酶对 slc26a3/6 的调节以及 CFTR 和 slc26a3/6 体外和体内的相互调节。 3.研究WNK上游激酶和信号通路以及WNK下游激酶在体内外对slc26a3/6调节的作用。 4. 检查 slc6a6 和 HCO3- 分泌在胰腺炎中的作用。 HCO3-分泌受损的slc26a6-/-小鼠将用于确定HCO3-分泌在急性胰腺炎的诱导和进展中的作用。拟议的工作应增进我们对胰管液和 HCO3 分泌的理解，并产生与胰腺炎和囊性纤维化相关的信息。 公共健康相关性：胰腺分泌消化酶和含有大量 HCO3- 的液体，将酶冲入肠道。需要 HCO3- 来防止酶过早激活，这样它们就不会消化胰腺本身。当 HCO3- 分泌异常时，胰腺会自行消化，如囊性纤维化和胰腺炎疾病中所发生的那样。这项工作旨在了解胰腺如何分泌 HCO3- 以及为什么胰腺炎和囊性纤维化中 HCO3- 分泌异常。