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

• 批准号: 8568088
• 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
• 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/8568088
• 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

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）对肾脏功能至关重要，也是受损肾脏病理的组成部分。它们是肾脏中对缺血和肾毒性损伤最敏感的细胞类型。PTC还参与控制炎症的信号传导途径，例如分泌细胞因子和将抗原呈递给MHC II，以及损伤后的消退。我们已经确定Kim-1是受损PTC中最高度上调的蛋白质。虽然Kim-1已被证明是检测肾损伤的一种有前途的诊断工具，但该蛋白质的病理生物学功能 其在肾损伤中的作用尚不清楚。我们的初步数据表明，Kim-1介导的吞噬作用诱导急性肾损伤后PTC的自噬和细胞保护作用。然而，Kim-1的长期表达会导致炎症和肾小管损伤，类似于慢性肾脏疾病。此外，我们发现Kim-1介导的吞噬作用和自噬诱导导致抗原呈递，并且根据Kim-1表达的配体和持续时间，结果可能是促炎或抗炎的。因此，我认为Kim-1介导的阿基中凋亡细胞的吞噬作用诱导自噬，这导致通过MHC呈递的免疫调节。在阿基中，自噬的后果是细胞保护性的，而在PT管腔含有其他Kim-1配体（如氧化脂质）和较少凋亡细胞的慢性状态下，Kim-1介导的这些配体的摄取诱导促炎性、促纤维化反应。这是一项多学科研究，将建立在我在细胞生物学方面的知识和研究技能的基础上，并将我的培训扩展到免疫学和小鼠遗传学等新领域。为了解决这一假设，我们将首先检查Kim-1在阿基中的保护作用是否是由于其自噬诱导。我们将测试金-1是否诱导 自噬对各种损伤具有保护作用。然后，我们将检查表达Kim-1黑色素细胞增多症缺陷小鼠的小鼠是否具有改变的自噬反应。了解Kim-1如何调节自噬，Kim-1磷酸化的作用及其与GABARAP（LC 3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，配体如ox-LDL的内吞作用导致线粒体片段化和半胱天冬酶活化。我们将测试可以摄取ox-LDL但不摄取凋亡细胞的wt Kim-1或Kim-1突变体的转基因过表达是否比既不摄取凋亡细胞也不摄取ox-LDL的突变体的过表达导致更大的损伤。然后，我们将测试在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分裂途径的激活，以及抑制线粒体片段化是否可以防止Kim-1介导的ox-LDL内吞诱导的细胞损伤。最后，我们将研究Kim-1诱导的自噬是否通过MHC呈递调节PTC免疫反应。我们将通过条件性敲除MHC II来研究MHC II提呈在阿基和CKD中的作用。然后，我们将确定表达Kim-1吞噬缺陷突变体的小鼠是否具有改变的免疫应答和自身抗体产生。由于近端小管细胞也表达共刺激和共抑制因子，我们将测试Kim-1诱导的自噬是否调节这些因子的表达。这项研究的结果将阐明Kim-1在急性和慢性肾损伤中的作用，并强调调节Kim-1功能的潜在治疗益处。 肾脏损伤