Role of KLF15 in proximal tubule metabolism

KLF15 在近曲小管代谢中的作用

• 批准号: 10481366
• 负责人: Sandeep K Mallipattu
• 金额: --
• 依托单位: NORTHPORT VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-01-01 至 2026-09-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10481366
• 关键词: Acetyl Coenzyme A; Acute Renal Failure with Renal Papillary Necrosis; Agonist; American; Anabolism; Aristolochic Acids; Attenuated; Binding Sites; Cardiovascular Diseases; Cell Cycle Arrest; Cell Differentiation process; Cell physiology; Cells; ChIP-seq; Chronic Kidney Failure; Cisplatin; Clinical; Compensation; DNA Damage; DNA Repair; Data; Diglycerides; Down-Regulation; Fatty Acids; Fibroblasts; Funding; General Population; Generations; Genes; Glycolysis; Goals; Human; Injury; Injury to Kidney; Ischemia; Kidney; Lipids; Mediating; Metabolic; Metabolic Pathway; Metabolism; Mitochondria; Mus; Myofibroblast; Nonesterified Fatty Acids; Organoids; Oxidative Stress; PPAR alpha; Palmitates; Pathway interactions; Phase; Pre-Clinical Model; Predisposition; Prevalence; Production; Profibrotic signal; Proliferating; Reactive Oxygen Species; Recovery; Regression Analysis; Regulation; Renal glomerular disease; Research; Respiration; Risk Factors; Role; Secondary to; Signal Transduction; Signaling Molecule; Source; Testing; Therapeutic; Toxin; Transcriptional Regulation; Triglycerides; United States Department of Veterans Affairs; Veterans; cardiovascular risk factor; cell dedifferentiation; cell injury; chemotherapeutic agent; clinically relevant; extracellular; in silico; inducible gene expression; interest; kidney biopsy; knock-down; macromolecule; mouse model; novel; novel therapeutic intervention; overexpression; oxidation; peroxidation; prevent; repaired; single nucleus RNA-sequencing; transcription factor; transcriptome sequencing

Chronic kidney disease (CKD) is a leading risk factor for cardiovascular disease, with a disproportionate burden on U.S. Veterans. Recent data demonstrates that acute kidney injury (AKI), despite initial renal recovery, is a major risk factor for CKD. The proximal tubule (PT) is the primary target in AKI due to its high susceptibility to ischemia and DNA-damaging nephrotoxins such as chemotherapeutic agents. Damaged PT cells dedifferentiate, and initially undergo cell cycle arrest, predominantly at the G2/M checkpoint. This cell cycle arrest may allow repair of DNA damage caused by reactive oxygen species secondary to mitochondrial damage or directly by DNA-damaging toxins. Sustained cell cycle arrest is associated with a switch to secretion of pro-fibrotic signaling molecules, inducing resident fibroblasts to proliferate and differentiate to myofibroblasts, beginning the transition to a fibrotic injury. PT cells also undergo metabolic reprograming, with severe downregulation of fatty acid b-oxidation (FAO), and limited compensation by anerobic glycolysis. While restoring FAO either by overexpressing Ppara or by using a peroxisome proliferator activated receptor alpha (PPARa) agonist attenuates AKI and CKD in murine models, this has not translated to use in clinical AKI, suggesting additional factors are required to mitigate the progression from AKI to CKD. Krüppel-Like Factor 15 (KLF15) is a kidney-enriched transcription factor, involved in a diverse range of cellular processes, including cell differentiation and FAO. In the initial funding period of the VA Merit, we demonstrated the salutary role of KLF15 in glomerular disease leading to a composition-of-matter IP on KLF15 agonists by the Veterans Affairs. During this initial period, we also identified that KLF15 is highly expressed in differentiated PT cells, but is significantly reduced in murine models of PT injury. Utilizing a murine model of PT-specific injury secondary to DNA damage, we observed that PT-specific knockdown of Klf15 exacerbated AKI as well as CKD. PT-specific knockdown of Klf15 also increased pathways involving cell cycle arrest, oxidative stress, pro-fibrotic signaling and a decrease in pathways utilizing FA for the generation of acetyl-CoA, a central metabolic intermediate in macromolecule biosynthesis and energy production. We also observed an enrichment of genes critical for FA utilization with putative and proximal KLF15- and PPARa-binding sites, suggesting potential KLF15-PPARa co-operativity in the regulation of FA utilization. In addition, we demonstrated a significant increase in glycerolipid synthesis pathways and lipid droplet formation in the setting of suppressed FAO, suggesting a potential compensatory mechanism post-DNA damage. KLF15 expression was also associated with PPARA expression in human kidney biopsies with and without CKD. In addition, multivariate regression analysis demonstrated that a decrease in KLF15 expression was independently associated with eGFR decline, suggesting that the loss of KLF15 might be a key driver of PT injury. Based on these preliminary data and strong scientific rigor of prior research, we hypothesize that KLF15-PPARa co-operativity drives the utilization of excess free fatty acids for acetyl-CoA and glycerolipid synthesis to prevent maladaptive PT repair post-DNA damage. We propose to test this hypothesis by (1) determining the mechanism by which KLF15-PPARa co-operativity restores PT metabolism after PT injury secondary to DNA-damage and (2) to investigate the requisite role of KLF15-PPARa in PT injury secondary to DNA-damage. This proposal will address a current gap in the field by investigating the mechanisms mediating transcriptional regulation of FA utilization in the PT cells post-DNA damage. The long-term goal of our project is to demonstrate that the combination of KLF15 and PPARa agonists is a novel therapeutic strategy to mitigate PT injury post-DNA damage. Identification of novel targets for the treatment of AKI is of major interest to the VA, given the high burden of CKD among U.S. Veterans.

慢性肾脏病（CKD）是心血管疾病的主要危险因素， 最近的数据表明，尽管急性肾损伤（AKI）对美国退伍军人造成了不成比例的负担。 初始肾脏恢复是 CKD 的主要危险因素，近曲小管 (PT) 是 AKI 的主要目标。 它对缺血和 DNA 损伤性肾毒素（例如化疗药物）高度敏感。 受损的 PT 细胞去分化，最初经历细胞周期停滞，主要是在 G2/M 检查点。 这种细胞周期停滞可能允许修复由继发性活性氧物质引起的 DNA 损伤。 线粒体损伤或直接损伤 DNA 的毒素与持续的细胞周期停滞有关。 转而分泌促纤维化信号分子，诱导常驻成纤维细胞增殖并 分化为肌成纤维细胞，开始转变为纤维化损伤 PT 细胞也经历代谢。 重编程，脂肪酸 b 氧化 (FAO) 严重下调，并且通过 通过过表达 Ppara 或使用过氧化物酶体增殖剂来恢复FAO。 激活受体 α (PPARa) 激动剂可减轻小鼠模型中的 AKI 和 CKD，但这尚未转化为 在临床 AKI 中的使用，表明需要其他因素来减缓从 AKI 到 CKD 的进展。 Krüppel 样因子 15 (KLF15) 是一种富含肾脏的转录因子，参与多种 细胞过程，包括细胞分化和FAO 在 VA Merit 的初始资助期间，我们。 证明了 KLF15 在肾小球疾病中的有益作用，导致对 KLF15 进行物质成分 IP 在此初始阶段，我们还发现 KLF15 在退伍军人事务部的激动剂中高度表达。 分化的 PT 细胞，但在 PT 损伤的小鼠模型中显着减少。 DNA 损伤继发的 PT 特异性损伤，我们观察到 Klf15 的 PT 特异性敲低加剧了 AKI 以及 CKD 特异性敲低 Klf15 也增加了涉及细胞周期停滞的途径， 氧化应激、促纤维化信号传导以及利用 FA 生成乙酰辅酶 A 的途径减少， 我们还观察到了大分子生物合成和能量生产的中心代谢中间体。 通过假定的和近端的 KLF15 和 PPARa 结合位点富集对 FA 利用至关重要的基因， 表明 KLF15-PPARa 在 FA 利用调节中具有潜在的协同作用。 甘油脂合成途径和脂滴形成显着增加 抑制FAO，表明KLF15表达后存在潜在的补偿机制。 还与患有和不患有 CKD 的人肾活检中 PPARA 的表达相关。 多变量回归分析表明，KLF15 表达的降低与 与 eGFR 下降相关，表明 KLF15 的缺失可能是 PT 损伤的关键驱动因素。 基于这些初步数据和强有力的科学研究，我们致力于 KLF15-PPARa 协同作用驱动过量游离脂肪酸对乙酰辅酶 A 和甘油脂的利用 我们建议通过 (1) 来检验这一假设。 确定 KLF15-PPARa 协同作用在 PT 损伤后恢复 PT 代谢的机制 (2) 研究 KLF15-PPARa 在继发于 DNA 损伤的 PT 损伤中的必要作用 该提案将通过研究介导机制来解决该领域目前的空白。 DNA 损伤后 PT 细胞中 FA 利用的转录调控 我们项目的长期目标。 是为了证明 KLF15 和 PPARa 激动剂的组合是一种新的治疗策略 减轻 DNA 损伤后的 PT 损伤 确定治疗 AKI 的新靶点具有重要意义。 鉴于美国退伍军人慢性肾病的负担很重，因此向退伍军人管理局提出了这一要求。