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.

该范式长期以来认为上皮 Na 通道 ENaC 与细胞旁 Cl- 吸收相结合， 是集合管中盐吸收的主要途径，而NCC是集合管中盐吸收的主要转运蛋白 DCT。过去十年的研究已经确定了跨细胞氯和/或钠的几个新参与者 集合管 (CD) 中的重吸收，包括 Cl-/HCO3- 交换器 Slc26a4 (pendrin)、Na+- 依赖的 Cl-/HCO3- 交换器 Slc4a8 (NDCBE) 和氯离子转运蛋白/通道 Slc26a11 (KBAT)。 与单独删除 NCC 或 pendrin 的小鼠不同，同时删除 pendrin 和 NCC 会导致急剧的 盐排泄增加，表明 NCC 和 pendrin 之间的交叉补偿及其在 盐的吸收。在髓质集合管中尚未发现跨细胞氯离子吸收途径。 我们实验室的新研究表明 Slc26a11 (KBAT) 在 A- 的顶膜上表达 CCD、OMCD 和 iIMCD 中的嵌入细胞在盐吸收中起着重要作用。原理图 图中的图表。图2、6和7描述了KBAT和pendrin与CCD中其他离子转运蛋白的相互作用。 初步结果：速尿治疗、NCC 或 pendrin 会增强 KBAT 表达 缺失和盐负载，增加了 KBAT 在环境中盐吸收中发挥重要作用的可能性 增强盐到集合管的输送。我们已经培育出具有肾脏特异性[（或全局）]的小鼠 KBAT 的消融，显示出袢利尿剂或增加盐分后显着的盐消耗 膳食盐摄入量。假设：我们假设 KBAT 在整个盐分吸收中发挥着重要作用。 集合管，交叉补偿 NCC 或 pendrin 失活和/或抑制并减轻盐损失 响应增加的盐输送到集合管。因此，我们预测 KBAT 失活将 在 NCC 或 pendrin 的情况下，利尿治疗导致过量的盐浪费 抑制/失活，以及对盐负荷的反应，后者反映了该转运蛋白在盐中的独特作用 盐充足状态下的吸收[以及盐/DOCA高血压]。最后，我们假设 KBAT 和 pendrin 与 ENaC 和/或 NDCBE [（后者的全局 KO 已在我们的实验室中生成）] 协同工作以重新吸收 CD 中的盐。创新：拟议的研究将阐明 KBAT 和 pendrin 作为主要参与者的作用 远端肾单位的盐重吸收和作为利尿治疗的新目标。方法：结合 基因工程小鼠模型、代谢平衡研究、肾小管微灌注、全身血液 通过遥测和分子研究进行压力测量将用于确定 KBAT 和 pendrin 参与盐重吸收并确定其在集合管中的钠吸收伙伴。洞察 KBAT 和 pendrin 的作用将显着增强我们对这些转运蛋白在盐中的作用的理解 重吸收和血压稳态。拟议的研究将进一步为发展奠定基础 KBAT 和 pendrin 抑制剂作为液体超负荷状态下的新型利尿剂。