Molecular Mechanisms of Ion Transport by the SMG

SMG 离子传输的分子机制

• 批准号: 7826631
• 负责人: PHILIP J THOMAS
• 金额: $ 37.28万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7826631
• 关键词: Acinar Cell; Bicarbonates; Biological Models; Cells; Collaborations; Cystic Fibrosis Transmembrane Conductance Regulator; Data; Dental caries; Deterioration; Development; Disease; Duct (organ) structure; Ductal; Electrolytes; Enzymes; Functional disorder; Gene Silencing; Goals; Health; Homeostasis; Human; Infection; Iodine; Ion Transport; Ions; Liquid substance; Malignant neoplasm of thyroid; Mammals; Measures; Mediating; Membrane Potentials; Metabolism; Molecular; Mucins; Mus; Nucleotides; Oral cavity; Oral health; Parotid Gland; Pathway interactions; Permeability; Pharmacology; Pharmacotherapy; Play; Preventive; Radiation therapy; Reading; Regulation; Research Personnel; Rest; Role; Saliva; Salivary Glands; Sjogren' s Syndrome; Small Interfering RNA; System; Testing; Time; Toxic effect; Work; Xerostomia; base; basolateral membrane; bean; clinical application; human DICER1 protein; inhibitor/antagonist; knock-down; luminal membrane; novel; novel strategies; prevent; programs; receptor; saliva secretion; seal; symporter; tool; uptake

DESCRIPTION (provided by applicant): Fluid and electrolyte transport is the central function of salivary glands (SG) that is critical for oral health. A critical aspect of SG secretion is the secretion of nearly 140 mM HCO3- by the duct in which CFTR plays a central role. In addition to functioning as a Cl channel CFTR regulates the activity of several Cl and HCO3- transporters at the luminal membrane, including the newly discovered CI/HCO3 and I-SLC26 transporters (SLCTs). Another physiologically and clinically important function of the duct that has never been studied is I-transport and homeostasis. SGs are destroyed during 1311 therapy of thyroid cancers. Our contributions to this topic are a) the electrogenicity of the SLC26Ts, b) the role of the SLC26Ts in ductal HCO3- secretion and their regulation by CFTR, c) the regulation of CFTR by the SLC26Ts, d) expression of the I-transporter slc26a4 in SG cells. Recently we also found a novel ADP-activated H?7HCO3- permeable pathway in parotid acinar and duct cells. 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 along the duct that are regulated by CFTR. In turn, the SLC26Ts suppress CFTR activity in the resting state and enhance CFTR activity at the stimulated state, which determines the final HCO3- content in the saliva. We also develop a new hypothesis of I-transport by SG cells. We will test this hypothesis in model systems AND NATIVE SG CELLS of WT, slc26a4-/- and slc26a6-/- mice in three Specific Aims: 1. Determine the transport mechanisms of the ADP- activated H?/HCO3- pathway and its role in ductal HCO3 secretion. 2. Study the role of slc26a4 and slc26a6 in SG fluid and HCO3- secretion using the KO mice. We also developed sealed ducts in primary culture in which transporters can be knocked down by dicer siRNA and in which we can measure directly fluid and HCO3- secretion. Systematic KD of SG SLC26Ts, pNBC and other HCO3- transporters will be used to study their role in ductal secretion. 3. Characterize the function of slc26a4 as an I-and HCO3- transporter and examine the role of the basolateral 2Na/l transporter NIS and the luminal slc26a4 in SG I-homeostasis and accumulation and their role in SG I-toxicity. The proposed work should advance our understanding of SG fluid and electrolyte secretion in health and disease and reveal for the first time the molecular bases for I-toxicity of SG during radiation therapy of thyroid cancers.

描述（由申请人提供）：液体和电解质运输是唾液腺（SG）的中心功能，对口腔健康至关重要。SG分泌的一个关键方面是由导管分泌近140 mM HCO 3-，其中CFTR起核心作用。除了作为Cl通道的功能外，CFTR还调节腔膜上几种Cl和HCO 3转运蛋白的活性，包括新发现的Cl/HCO 3和I-SLC 26转运蛋白（SLCT）。另一个从未被研究过的导管的生理和临床重要功能是I-运输和稳态。在甲状腺癌的1311治疗期间，SG被破坏。我们的贡献是a）SLC 26 Ts的产电性，B）SLC 26 Ts在导管HCO 3-分泌中的作用及其通过CFTR的调节，c）SLC 26 Ts对CFTR的调节，d）I-转运蛋白slc 26 a4在SG细胞中的表达。最近，我们还发现了一个新的ADP激活的H？腮腺腺泡和导管细胞中的7 HCO 3渗透通路。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调节的沿着导管的不同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，这决定了唾液中最终的HCO 3含量。我们还开发了一个新的假说，I-运输SG细胞。我们将在WT、slc 26 a4-/-和slc 26 a6-/-小鼠的模型系统和天然SG细胞中测试这一假设，具体目的如下：确定ADP激活的H？/ HCO 3-途径及其在导管HCO 3分泌中的作用2.使用KO小鼠研究slc 26 a4和slc 26 a6在SG液和HCO 3-分泌中的作用。我们还在原代培养中开发了密封导管，其中转运蛋白可以被dicer siRNA敲除，并且我们可以直接测量液体和HCO 3分泌。SG SLC 26 Ts、pNBC和其他HCO 3转运蛋白的系统KD将用于研究它们在导管分泌中的作用。3.表征slc 26 a4作为I-和HCO 3-转运蛋白的功能，并检查基底外侧2Na/l转运蛋白NIS和管腔slc 26 a4在SG I-稳态和蓄积中的作用及其在SG I-毒性中的作用。拟议中的工作应推进我们的了解SG液体和电解质分泌的健康和疾病，并首次揭示了甲状腺癌放射治疗过程中的SG的I-毒性的分子基础。