The role of collecting duct chloride transporters in salt absorption and blood pressure homeostasis

集合管氯离子转运蛋白在盐吸收和血压稳态中的作用

• 批准号: 9898225
• 负责人: MANOOCHER SOLEIMANI
• 金额: --
• 依托单位: ALBUQUERQUE VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2022-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9898225
• 关键词: Ablation; Aldosterone; Amiloride; Animals; Anions; Bicarbonates; Blood Pressure; Blood Vessels; Blood Volume; Carrier Proteins; Chlorides; Clustered Regularly Interspaced Short Palindromic Repeats; Collaborations; Congestive Heart Failure; DOCA; Development; Disease; Distal; Diuresis; Diuretics; Duct (organ) structure; Enterobacteria phage P1 Cre recombinase; Equilibrium; Excess Dietary Salt; Excretory function; Exhibits; Family; Financial compensation; Fluid overload; Fluorescence; Furosemide; Genes; Genetically Engineered Mouse; Goals; Health; Homeostasis; Hospitals; Hydrochlorothiazide; Hypertension; Intercalated Cell; Ions; Kidney; Knockout Mice; Laboratories; Length; Liquid substance; Measurement; Mediating; Metabolic; Molecular; Monitor; Mus; Nephrons; Pathogenesis; Pathway interactions; Patients; Phenotype; Play; Radioactive; Regulation; Research; Research Personnel; Role; SLC12A3 gene; Sodium; Sodium Chloride; Systemic blood pressure; Telemetry; Therapeutic; Veterans; Work; absorption; apical membrane; blood pressure regulation; collecting tubule structure; design; dietary salt; epithelial Na+ channel; inhibitor/antagonist; innovation; insight; member; mutant; mutant mouse model; novel; patch clamp; response; salt intake; thiazide; wasting

The paradigm has long held that the epithelial Na channel ENaC, in conjunction with paracellular Cl- absorption, is the major path for salt absorption in the collecting duct whereas NCC is the main salt absorbing transporter in the DCT. Studies over the last decade have identified several new players in transcellular chloride and/or sodium reabsorption in the collecting duct (CD), including the Cl-/HCO3- exchanger Slc26a4 (pendrin), the Na+- dependent Cl-/HCO3- exchanger Slc4a8 (NDCBE), and the chloride transporter/channel Slc26a11 (KBAT). Unlike mice with single deletion of NCC or pendrin, simultaneous deletion of pendrin and NCC causes sharp increases in salt excretion, pointing to cross compensation between NCC and pendrin and their crucial role in salt absorption. No transcellular chloride-absorbing pathway has been identified in medullary collecting duct. New studies from our laboratory demonstrate that Slc26a11 (KBAT) is expressed on the apical membrane of A- intercalated cells in CCD, OMCD and iIMCD and plays an important role in salt absorption. The schematic diagrams in Figs. 2, 6 and 7 depict the interaction of KBAT and pendrin with other ion transporters in the CCD. Preliminary results: KBAT expression is enhanced in response to furosemide treatment, NCC or pendrin deletion, and salt loading, raising the possibility that KBAT plays an important role in salt absorption in the setting of enhanced delivery of salt to the collecting duct. We have generated mice with kidney specific [(or global)] ablation of KBAT, which show significant salt wasting in response to the loop diuretics or following increased dietary salt intake. Hypothesis: We hypothesize that KBAT plays an important role in salt absorption in the entire collecting duct, cross compensates for NCC or pendrin inactivation and/or inhibition and mitigates the salt loss in response to enhanced salt delivery to the collecting duct. As a result, we predict that KBAT inactivation will result in excess salt wasting consequent to diuretic therapy, in the setting of NCC or pendrin inhibition/inactivation, and in response to salt loading, the latter reflecting a unique role for this transporter in salt absorption in salt replete states [and in salt/DOCA hypertension]. Lastly, we hypothesize that KBAT and pendrin work in tandem with ENaC and/or NDCBE [(the global KO of the latter has been generated in our lab)] to reabsorb salt in CD. Innovation: The proposed research will elucidate the role of KBAT and pendrin as major players in salt reabsorption in distal nephron and as novel targets for diuretic therapy. Approach: A combination of genetically engineered mouse models, metabolic balance studies, tubule microperfusion, systemic blood pressure measurement by telemetry and molecular studies will be employed to ascertain the role of KBAT and pendrin in salt reabsorption and identify their sodium absorbing partners in the collecting duct. Insight into the role of KBAT and pendrin will significantly enhance our understanding of the role of these transporters in salt reabsorption and blood pressure homeostasis. The proposed studies will further lay the ground for development of inhibitors of KBAT and pendrin as novel diuretics in fluid overloaded states.

长期以来，该范式一直认为，上皮性钠通道ENaC与细胞旁的氯离子吸收相结合， NCC是集输管道中盐分吸收的主要途径，而NCC是土壤中主要的盐分输运体 DCT。过去十年的研究已经确定了几个跨细胞氯和/或钠的新角色。 在收集管(CD)中的重吸收，包括Cl-/HCO3-交换器SLC26A4(吊环)，Na+- 依赖的氯/HCO3-交换器Slc4a8(NDCBE)和氯转运体/通道Slc26a11(KBAT)。 与单一缺失NCC或NCC的小鼠不同，同时缺失Pendrin和NCC会导致急剧 盐排泄增加，表明NCC和Pendrin之间的交叉补偿以及它们在 盐分吸收。在髓质集合管中没有发现跨细胞的氯离子吸收途径。 本实验室的最新研究表明，SLC26a11(KBAT)表达于A-B细胞的顶膜上。 插层细胞存在于CCDs、OMCD和iIMCD中，在盐吸收过程中起着重要作用。原理图 图2、图6和图7中的图表描述了KBAT和Pendrin与CCD中的其他离子转运体的相互作用。 初步结果：速尿、NCC或Pendrin治疗后KBAT表达增强 缺失和盐分负荷，增加了KBAT在环境中盐分吸收中发挥重要作用的可能性 提高了向收集管道输送盐分的能力。我们已经培育出具有肾脏特异性[(或全局)]的小鼠 消融KBAT，对循环利尿剂或以下增加的反应显示显著的盐浪费 食盐摄入量。假设：我们假设KBAT在整个盐分吸收过程中起着重要作用。 收集管道，交叉补偿NCC或吊环蛋白失活和/或抑制，并减轻盐分损失 以应对向收集管道输送更多盐分的情况。因此，我们预测KBAT失活将 导致利尿剂治疗导致的过量盐浪费，在NCC或吊环的环境中 抑制/失活，以及对盐负荷的响应，后者反映了该转运蛋白在盐中的独特作用 在盐充足状态下的吸收[以及在盐/DOCA高血压中]。最后，我们假设KBAT和吊环 与ENaC和/或NDCBE[(后者的全球KO已在我们的实验室中生成)]合作，以重新吸收 CD里的盐。创新：拟议的研究将阐明KBAT和Pendrin作为主要参与者在 远端肾单位的盐重吸收和利尿治疗的新靶点。方法：结合以下几点 基因工程小鼠模型，代谢平衡研究，小管微灌注，全身血液 将利用遥测压力测量和分子研究来确定KBAT和 在盐重吸收过程中的侧链蛋白，并确定它们在收集管道中的钠吸收伙伴。洞察 KBAT和Pendrin的作用将大大增强我们对这些转运蛋白在盐中的作用的理解 重吸收和血压动态平衡。建议的研究将进一步为发展奠定基础。 在液体超负荷状态下，KBAT和垂垂蛋白的抑制剂作为新型利尿剂的研究。