Lipid Rafts: Mechanosensors of the distal nephron

脂筏：远端肾单位的机械传感器

• 批准号: 10552548
• 负责人: RAJEEV ROHATGI
• 金额: --
• 依托单位: JAMES J PETERS VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-10-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10552548
• 关键词: ATP-Binding Cassette Transporters; Ablation; Active Biological Transport; Adult; Affect; Amino Acids; Apolipoprotein E; Apolipoproteins; Apoptosis; Atherosclerosis; Automobile Driving; Avidity; Blood Pressure; Cardiovascular system; Cell Nucleus; Cells; Ceramides; Cholesterol; Cilia; Clinical; Complex; Consensus Sequence; Data; Development; Diet; Dinoprostone; Disease; Distal; Duct (organ) structure; Electrophysiology (science); Environmental Risk Factor; Epidemiology; Epithelium; Essential Hypertension; Excess Mortality; Excretory function; Functional disorder; Genetic; Genetic Polymorphism; High Density Lipoproteins; Human; Hypertension; Inflammation; Inflammatory; Investigation; K ATPase; Kidney; Kidney Diseases; Knock-out; Lead; Length; Ligands; Link; Lipid Peroxidation; Lipid Peroxides; Liquid substance; Low-Density Lipoproteins; Mediating; Membrane Microdomains; Methods; Mitochondria; Molecular; Mus; Mutation; NOS1 gene; NOS3 gene; Natriuresis; Natriuretic Factors; Nephrons; Organ; Outcome; Oxidative Stress; P2Y2 receptor; Pathway interactions; Phenotype; Physiological; Population; Pre-Eclampsia; Prognosis; Proteins; Repression; Research; Resistance; Resistant Hypertension; Respiration; Risk; Risk Factors; SR-BI receptor; Serum; Signal Transduction; Sodium; Sodium Chloride; Sphingomyelinase; Sphingomyelins; Stress; Systemic blood pressure; Systemic hypertension; TLR2 gene; TLR4 gene; Tangier Disease; Testing; Tissues; Tubular formation; Variant; absorption; autocrine; cyclooxygenase 2; density; design; dietary; epithelial Na+ channel; inflammatory marker; knock-down; mortality; mouse model; novel; paracrine; pharmacologic; premature atherosclerosis; recruit; response; risk variant; salt sensitive hypertension; saluretic; shear stress; symporter; transcriptome sequencing; urinary

Hypertension (HTN) affects millions of adults in the U.S and leads to end organ damage. This study is designed to test whether dysregulation of the cholesterol (chol) efflux pathway affects sodium (Na) dependent rise in systemic blood pressure (BP), both of which are risk factors for mortality. The chol efflux pathway is comprised of two pathways, (1) facilitated chol transport or (2) the active transport pathway regulated by ATP-binding cassette (ABC) transporters, ABC transporter A1 (ABCA1) and ABC transporter G1 (ABCG1). ABCA1 polymorphisms, that repress chol efflux, are associated with HTN while non-functional mutations of ABCA1 cause Tangiers disease with early atherosclerosis. High Na diets increase tubular flow that stimulate paracrine pathways to suppress Na absorption and, thus, enhance Na excretion; as a corollary, targeted deletion of flow-mediated autocrine-paracrine pathways enhance renal Na avidity and HTN. Renal prostaglandin E2 (PGE2) knock out (KO) causes Na sensitive HTN. Moreover, increases in tubular flow induce cyclooxygenase-2 (COX2) activity/protein and collecting duct (CD) PGE2 release to inhibit epithelial Na channel (ENaC). The effects of flow on COX2 and PGE2 are muted in CDs isolated from mice fed a 1% chol vs. no chol diet. The chol content from chol fed mice doubles versus controls. ABCA1 ablation in CDs, increases CD chol, stimulates ENaC, reduces urinary ATP and raises BP. ABCA1 ablation also predisposes to an inflammatory renal microenvironment. Increases of LR free chol enhance ligand-dependent toll-like receptor (TLR) 4 signaling which is linked to tubular Na transport. Elevated LR free chol recruit TLR4 to LRs, increasing LR TLR4 density, to augment signaling. Transepithelial Na transport stimulates Na/K-ATPase mediated ATP demand driving mitochondrial oxidative respiration, oxidative stress, lipid peroxidation and ferroptosis. TLR4 is stimulated by stress induced ligands including lipid peroxides leading to an inflammatory and Na avid phenotype. Thus, we hypothesize that excess tubular PM/LR chol content in ABCA1 deficient tubules will induce Na avidity and inflammation due to muted flow mediated natriuretic pathways, primed TLR4 responses, and transport dependent oxidative respiration and stress to form the Na sensitive phenotype. This will be tested in the specific aims (SAs): SA1. To evaluate whether depletion or deletion of tubular ABCA1 expression contributes to the development of renal Na avidity and HTN SA1a. Test whether tubular ABCA1 ablation is sufficient or dietary chol is necessary to induce Na sensitivity. SA1b. Determine whether serum LDL level modifies the Na avidity by crossing ABCA1fl/fl (ABCA1 FF) mice into the apolipoprotein E (APOE) deficient mouse SA2. Test whether chol affects PM/LR function to repress flow mediated Na excretory pathways and augment TLR4 inflammatory signaling to promote anti-natriuresis and HTN SA2a. Test whether chol incorporation into LRs directly enhances Na transport and represses FSS induced natriuretic factors to augment Na absorption using molecular, physiologic and electrophysiologic methods. SA2.b Determine whether altering the PM chol, and specifically, LR chol effects TLR4 density and activation, and, hence, inflammatory markers and transepithelial Na transport. SA2.c Test whether pharmacologic PM chol depletion reverses Na sensitivity and inflammation. SA3. Greater rates of Na transport in ABCA1 deficient mice increase oxidative respiration and stress that activates the ferropotic pathway, based on single nuclei RNAseq (snRNAseq) data. SA3a. Determine whether greater Na/K-ATPase activity is driving greater mitochondrial respiration and oxidative stress in ABCA1 deficient kidneys. SA3b. Characterize if increased mitochondrial respiration and stress augments ferroptosis in tubular epithelia.

高血压 (HTN) 影响着美国数百万成年人，并导致终末器官损伤。这项研究是 旨在测试胆固醇 (chol) 流出途径的失调是否会影响钠 (Na) 依赖性 全身血压（BP）升高，这两者都是死亡的危险因素。 胆汁流出途径由两条途径组成：(1) 促进胆汁转运或 (2) 活性胆汁转运 转运途径受 ATP 结合盒 (ABC) 转运蛋白、ABC 转运蛋白 A1 (ABCA1) 和 ABC 转运蛋白 G1 (ABCG1)。 ABCA1 多态性可抑制胆汁外流，与 HTN 相关，而 ABCA1 的非功能性突变会导致丹吉尔病并伴有早期动脉粥样硬化。 高钠饮食会增加肾小管流量，刺激旁分泌途径，抑制钠吸收， 从而增强Na的排泄；作为推论，有针对性地删除流介导的自分泌-旁分泌途径 增强肾Na亲和力和HTN。肾前列腺素 E2 (PGE2) 敲除 (KO) 导致 Na 敏感 HTN。此外，肾小管流量的增加会诱导环氧合酶-2 (COX2) 活性/蛋白质和集合管 (CD) PGE2 释放以抑制上皮钠离子通道 (ENaC)。流量对 COX2 和 PGE2 的影响减弱 在从喂食 1% 胆汁和无胆汁饮食的小鼠中分离出的 CD 中。喂食胆汁的小鼠的胆汁含量比 控制。 CD 中的 ABCA1 消除，增加 CD 胆碱，刺激 ENaC，减少尿 ATP 并升高血压。 ABCA1 消融也容易产生炎症性肾脏微环境。 LR免费增加 chol 增强配体依赖性 Toll 样受体 (TLR) 4 信号传导，该信号与肾小管 Na 转运有关。 升高的 LR 游离胆将 TLR4 募集至 LR，增加 LR TLR4 密度，以增强信号传导。跨上皮 Na 转运刺激 Na/K-ATP 酶介导的 ATP 需求，驱动线粒体氧化呼吸， 氧化应激、脂质过氧化和铁死亡。 TLR4 受到应激诱导的配体（包括脂质）的刺激 过氧化物导致炎症和嗜钠表型。因此，我们假设多余的肾小管 ABCA1 缺陷小管中的 PM/LR 胆含量会因沉默而诱导 Na 亲和力和炎症 血流介导的利尿钠途径、引发的 TLR4 反应和转运依赖性氧化 呼吸和应激形成Na敏感表型。这将在特定目标 (SA) 中进行测试： SA1。评估肾小管 ABCA1 表达的耗尽或缺失是否会导致 肾Na亲和力和HTN的发展 SA1a。测试肾小管 ABCA1 消融是否足够，或者膳食胆碱是否是诱导 Na 敏感性所必需的。 SA1b。通过将 ABCA1fl/fl (ABCA1 FF) 小鼠杂交到 载脂蛋白 E (APOE) 缺陷小鼠 SA2。测试 chol 是否影响 PM/LR 功能以抑制血流介导的 Na 排泄途径和 增强 TLR4 炎症信号传导以促进抗尿钠排泄和高血压 SA2a。测试将 chol 掺入 LR 中是否会直接增强 Na 转运并抑制 FSS 诱导的 使用分子、生理学和电生理学方法增加钠吸收的利尿钠因子。 SA2.b 确定改变 PM chol，特别是 LR chol 是否会影响 TLR4 密度和激活， 因此，炎症标志物和跨上皮钠转运。 SA2.c 测试药理学 PM 胆消耗是否可逆转 Na 敏感性和炎症。 SA3。 ABCA1 缺陷小鼠的 Na 转运速率加快会增加氧化呼吸和应激 基于单核 RNAseq (snRNAseq) 数据激活铁细胞通路。 SA3a。确定更高的 Na/K-ATP 酶活性是否会驱动更大的线粒体呼吸，以及 ABCA1 缺陷肾脏中的氧化应激。 SA3b。表征线粒体呼吸和应激的增加是否会加剧肾小管上皮细胞的铁死亡。