Proximal tubule Kim-1 expression modulates acute and chronic kidney injury

近端小管 Kim-1 表达调节急性和慢性肾损伤

基本信息

批准号：
8699766
负责人：
Craig Robert Brooks
金额：
$ 15.74万
依托单位：
BRIGHAM AND WOMEN'S HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-08-01 至 2018-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8699766
关键词：
Acute Acute Renal Failure with Renal Papillary Necrosis Address Animal Model Anti-Inflammatory Agents Anti-inflammatory Antigen Presentation Apoptotic Area Autoantibodies Autoimmunity Autophagocytosis Birth Caspase Cell Death Cells Cellular biology Chronic Chronic Kidney Failure Clinical Cytoprotection Data Diagnostic Endocytosis Epithelial Cells Family member Genetic Goals Immune response Immunology Inflammation Inflammatory Inflammatory Response Injury Injury to Kidney Ischemia Kidney Knock-out Knowledge Laboratories Ligand Binding Ligands Light Major Histocompatibility Complex Mediating Mentors Mitochondria Modeling Morbidity - disease rate Mucins Mus Nephrotoxic Outcome Pathology Pathway interactions Patients Phagocytes Phagocytosis Phosphatidylserines Phosphorylation Production Proteins Proximal Kidney Tubules Renal function Research Research Personnel Resistance Resolution Role Signal Pathway Testing Therapeutic Training Transgenic Mice Transgenic Organisms Tubular formation Tyrosine Phosphorylation cell injury cell type cytokine glomerular filtration immunoregulation in vivo injured mortality mouse model multidisciplinary mutant novel overexpression oxidized lipid oxidized low density lipoprotein prevent protective effect protein function public health relevance rat KIM-1 protein response scavenger receptor skills therapeutic target tool uptake

项目摘要

DESCRIPTION (provided by applicant): Renal proximal tubule epithelial cells (PTCs) are vital to the function of the kidney and are also integral to the pathology of the injured kidney. They are the most sensitive cell type in the kidney to ischemia and nephrotoxic insults. PTCs are also involved in the signaling pathways governing inflammation, such as secretion of cytokines and presentation of antigens to MHC II, and resolution following injury. We have identified Kim-1 as the most highly upregulated protein in injured PTCs. While Kim-1 has been shown to be a promising diagnostic tool for detecting kidney injury, the pathobiological function of this protein and its role in kidney injury are not known. Our preliminary data suggest that Kim-1-mediated phagocytosis induces autophagy and cytoprotection in PTCs following acute kidney injury. Prolonged expression of Kim-1, however, leads to inflammation and tubule damage, mimicking chronic kidney disease. Furthermore, we have found that Kim-1-mediated phagocytosis and autophagy induction leads to antigen presentation, and depending on the ligands and duration of Kim-1 expression, the outcome could be pro or anti-inflammatory. Therefore, I propose that Kim-1 mediated phagocytosis of apoptotic cells in AKI induces autophagy, which leads to immune modulation through MHC presentation. In AKI, the consequences of autophagy are cytoprotective while in chronic states where the PT lumen contains other Kim-1 ligands, such as oxidized lipids, and fewer apoptotic cells, Kim-1 mediated uptake of these ligands induces a pro-inflammatory, profibrotic response. This is a multidisciplinary study that will build on my knowledge and research skills in cell biology and extend my training into novel areas such as immunology and mouse genetics. To address this hypothesis we will first examine if the protective effect of Kim-1 in AKI is due to its autophagy induction. We will test if Kim- 1-induced autophagy is protective against various insults. Then we will examine if mice expressing a Kim-1 phaogocytosis deficient mouse has an altered autophagic response. To understand how Kim-1 regulates autophagy, the role of Kim-1 phosphorylation and its interaction with GABARAP (an LC3 family member) in autophagy induction. Second, we will determine if Kim-1-mediated endocytosis contributes to chronic injury. Unlike phagocytosis of apoptotic cells, endocytosis of ligands such as ox-LDL, leads to mitochondrial fragmentation and caspase activation. We will test if transgenic overexpression of wt Kim-1 or Kim-1 mutant which can take up ox-LDL but not apoptotic cells leads to greater injury than overexpression of a mutant which takes up neither apoptotic cells or ox-LDL. We will then test if the mitochondrial fragmentation observed following Kim-1-mediated uptake of ox-LDL is due to activation of the mitochondrial fission pathway and whether inhibiting mitochondrial fragmentation prevents cellular injury induced by Kim-1-mediated endocytosis of ox-LDL. Finally, we will examine if Kim-1-induced autophagy modulates the PTC immune response through MHC presentation. We will examine the role of MHC II presentation in AKI and CKD through conditional knockout of MHC II. We will then determine if mice expressing Kim-1 phagocytosis deficient mutant have an altered immune response and autoantibody production. As proximal tubule cells also express co-stimulatory and co-inhibitory factors, we will test if Kim-1 induced autophagy modulates the expression of these factors. The findings from this study will shed light on the role of Kim-1 in acute and chronic kidney injury, as well as highlight the potential therapeutic benefits of modulating Kim-1 function in kidney injury.

描述（由申请人提供）：肾近端小管上皮细胞（PTC）对于肾脏功能至关重要，也是受伤肾脏的病理学不可或缺的。它们是缺血和肾毒性损伤中肾脏中最敏感的细胞类型。 PTC还参与了控制炎症的信号通路，例如细胞因子的分泌和抗原向MHC II的表现以及损伤后的分辨率。我们已经确定KIM-1是受伤的PTC中最高度上调的蛋白质。尽管KIM-1已被证明是检测肾脏损伤的有前途的诊断工具，但该蛋白的病理学功能它在肾脏损伤中的作用尚不清楚。我们的初步数据表明，急性肾损伤后，KIM-1介导的吞噬作用在PTC中诱导自噬和细胞保护作用。但是，长期表达KIM-1会导致炎症和小管损伤，模仿慢性肾脏疾病。此外，我们发现KIM-1介导的吞噬作用和自噬诱导会导致抗原表现，并取决于KIM-1表达的配体和持续时间，结果可能是pro或抗炎的。因此，我提出KIM-1介导的AKI凋亡细胞吞噬作用会诱导自噬，从而通过MHC表现导致免疫调节。在AKI中，自噬的后果是细胞保护的，而在慢性状态下，PT Lumen含有其他KIM-1配体（例如氧化脂质），而凋亡细胞较少，KIM-1介导的这些配体的摄取会诱导促触发感染的功能纤维化，纤维化，纤维化反应。这是一项多学科研究，它将基于我的细胞生物学知识和研究技能，并将我的培训扩展到新颖的领域，例如免疫学和小鼠遗传学。为了解决这一假设，我们将首先检查KIM-1在AKI中的保护作用是否是由于其自噬诱导。我们将测试Kim-1诱导的自噬可防止各种侮辱。然后，我们将检查表达Kim-1杂细胞增多症缺乏小鼠的小鼠是否会改变自噬反应。为了了解KIM-1如何调节自噬，KIM-1磷酸化的作用及其与Gabarap（LC3家族成员）在自噬诱导中的相互作用。其次，我们将确定KIM-1介导的内吞作用是否有助于慢性损伤。与凋亡细胞的吞噬作用不同，诸如OX-LDL等配体的内吞作用会导致线粒体碎裂和caspase激活。我们将测试WT KIM-1或KIM-1突变体的转基因过表达是否会占用OX-LDL但不能导致凋亡细胞会导致损伤更大，而不是占用凋亡细胞或OX-LDL的突变体的过表达。然后，我们将测试KIM-1介导的OX-LDL摄取后观察到的线粒体片段化是否是由于线粒体裂变途径的激活以及抑制线粒体碎片化是否会预防由KIM-1-1-介导的Ox-LDL诱导的线粒体碎片。最后，我们将检查KIM-1诱导的自噬是否通过MHC表现调节PTC免疫反应。我们将通过MHC II的条件敲除在AKI和CKD中的MHC II表现的作用。然后，我们将确定表达KIM-1吞噬作用缺陷突变体的小鼠是否会改变免疫反应和自身抗体的产生。由于近端小管细胞也表达了共刺激性和共抑制因素，我们将测试KIM-1诱导的自噬是否调节这些因素的表达。这项研究的发现将阐明KIM-1在急性和慢性肾脏损伤中的作用，并突出调节KIM-1功能的潜在治疗益处在肾脏受伤中。