Pathogenesis of tubule atrophy and failed recovery after acute kidney injury

急性肾损伤后肾小管萎缩及恢复失败的发病机制

基本信息

批准号：
9198226
负责人：
MANJERI A VENKATACHALAM
金额：
$ 34.31万
依托单位：
UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-01-01 至 2019-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9198226
关键词：
Acute Renal Failure with Renal Papillary Necrosis Address Atrophic Autophagocytosis BRCA1 gene Cell Proliferation Cells Chronic Chronic Kidney Failure DNA DNA Damage DNA Double Strand Break DNA Repair DNA biosynthesis DNA-dependent protein kinase Data Defect Deoxyribonucleotides Development Dialysis procedure Environment Event Exhibits FRAP1 gene Fibrosis GADD45A gene Gamma-H2AX Gene Expression Genes Genetic Transcription Growth H2AFX gene HIF1A gene Health Healthcare Hypoxia Immunohistochemistry Impairment Incidence Inflammation Infusion procedures Intervention Investigation Kidney Kidney Diseases Laboratories MAPK14 gene MAPK8 gene Measures Messenger RNA Morbidity - disease rate Mus Natural regeneration Nuclear Oxygen Pathogenesis Pathology Phenotype Phosphotransferases Plant Roots Proliferating Protein Analysis Proteomics Publishing RNA Probes RNA analysis Recovery Renal tubule structure Reperfusion Injury Reporter Research Ribonucleotide Reductase Ribonucleotides Risk Role Signal Transduction Signaling Protein Stress Structure TSC2 gene Testing Transgenes Transgenic Organisms Transplantation Undifferentiated Western Blotting Work base deoxyribonucleoside triphosphate homologous recombination hypoxia inducible factor 1 in vivo innovation insight knock-down morphometry mortality new therapeutic target overexpression prevent programs public health relevance recombinational repair repaired response transcriptome sequencing tripolyphosphate

项目摘要

DESCRIPTION (provided by applicant): Tubule atrophy and fibrosis often develop after acute kidney injury (AKI) favoring transition to chronic kidney disease (CKD). The AKI-CKD transition has major implications, but poorly understood. We found that tubules regenerating after AKI often fail to differentiate. Such tubules are growth arrested and atrophic, and exhibit signaling that drives fibrosis. The cause of this pathology is unknown. We obtained three lines of evidence that could explain why recovering tubules become atrophic and profibrotic. First, tubules showed damage to DNA and DNA damage repair responses (DDR) during ischemic AKI, and then, instead of subsiding, DNA damage and DDRs persisted into later stages of tubule atrophy and fibrosis. Altered gene expression caused by DNA damage may explain why tubules fail to recover normally. Chronic hypoxia in kidneys recovering from AKI could inhibit oxygen dependent ribonucleotide reductase (RNR) in tubules causing depletion of deoxynucleotide triphosphates (dNTPs) and thereby produce DNA damage. Second, dNTPs declined in hypoxic cultured tubule cells, producing DNA damage and DDRs. This was accompanied by growth arrest and a dedifferentiated abnormally signaling profibrotic phenotype similar to that seen during tubule atrophy after AKI in vivo. Provision of dNTP precursors ameliorated the hypoxic DNA damage and reversed the growth arrest. Third, by RNAseq transcriptional profiling of hypoxic cells, we identified increased expression of genes related to inflammation, atrophy and fibrosis. Our hypothesis is that following ischemic AKI, chronic hypoxia inhibits ribonucleotide reductase (RNR) in regenerating tubules, depletes dNTPs, and, thereby, causes DNA replication stress and DNA damage. Because DNA damage is chronic, the DNA damage repair response (DDR) also persists, giving rise to inflammation, atrophy and fibrosis. To test this hypothesis, we have three Specific Aims. In Aim 1 we will explore the relationships between DNA damage and development of tubule atrophy using immunohistochemistry and morphometry, a transgenic reporter DNA damage, and inducible deletion of critical DDR genes to investigate if the intervention modifies late pathology after AKI In Aim 2, we will investigate the relationships of hypoxic inhibition of RNR, dNTP depletion, DNA damage/DDR and cell pathology. We will determine if infusions of dNTP precursors in vivo ameliorate tubule pathology after AKI. In Aim 3, we will use RNAseq and proteomics to selectively identify hypoxic alterations specific to dNTP depletion as apart from other hypoxic effects. Thus, we hope to provide critically needed information relating to basic aspects in the pathogenesis of a major health problem, chronic kidney disease.

描述（由申请人提供）：急性肾损伤（AKI）后经常出现肾小管萎缩和纤维化，有利于向慢性肾病（CKD）转变。AKI-CKD 转变具有重要意义，但我们发现 AKI 后肾小管再生的情况知之甚少。这些小管通常无法分化，并表现出驱动纤维化的信号。我们获得了三个可以解释为什么会恢复的证据。首先，在缺血性 AKI 期间，肾小管出现 DNA 损伤和 DNA 损伤修复反应 (DDR)，然后，DNA 损伤和 DDR 并没有消退，而是持续到肾小管萎缩和纤维化的后期阶段，导致基因表达改变。 DNA 损伤可能解释了为什么从 AKI 中恢复的肾脏中的慢性缺氧可能会抑制氧依赖性核糖核苷酸还原酶 (RNR)。其次，缺氧培养的肾小管细胞中 dNTP 减少，产生 DNA 损伤和 DDR，这伴随着生长停滞和类似于肾小管期间观察到的去分化异常信号促纤维化表型。体内 AKI 后的萎缩，提供 dNTP 前体可改善缺氧 DNA 损伤并逆转生长停滞。通过对缺氧细胞的转录分析，我们发现与炎症、萎缩和纤维化相关的基因表达增加。我们的假设是，缺血性 AKI 后，慢性缺氧会抑制肾小管再生中的核糖核苷酸还原酶 (RNR)，耗尽 dNTP，从而导致 DNA 复制。由于 DNA 损伤是慢性的，DNA 损伤修复反应 (DDR) 也会持续存在，从而引起炎症、萎缩和纤维化。为了检验这一假设，我们有三个具体目标。在目标 1 中，我们将使用免疫组织化学和形态测定法、转基因报告 DNA 损伤和关键 DDR 基因的诱导删除来探索 DNA 损伤与肾小管萎缩发展之间的关系，以研究干预措施是否会改变。 AKI 后的晚期病理学在目标 2 中，我们将研究 RNR 的缺氧抑制、dNTP 耗竭、DNA 损伤/DDR 和细胞病理学之间的关系。体内输注 dNTP 前体可改善 AKI 后的肾小管病理学。在目标 3 中，我们将使用 RNAseq 和蛋白质组学来选择性识别 dNTP 耗竭所特有的缺氧改变以及其他缺氧效应。因此，我们希望提供与基本缺氧相关的急需信息。一个主要健康问题——慢性肾脏病的发病机制。