Novel roles of integrin b1 signaling in regulating principal cell function andmaintaining collecting duct integrity

整合素b1信号在调节主要细胞功能和维持集合管完整性中的新作用

• 批准号: 10220019
• 负责人: HUA A LU
• 金额: $ 37.3万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-20 至 2023-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10220019
• 关键词: Actins; Acute; Adult; Age; Animals; Apoptosis; CD29 Antigen; Cell Adhesion Molecules; Cell Cycle Arrest; Cell physiology; Cells; Cues; Cultured Cells; Cytoskeleton; Data; Disease; Diuresis; Duct (organ) structure; Ductal Epithelium; ECM receptor; Endocytosis; Epithelial; Exocytosis; Extracellular Matrix; Fibrosis; Focal Adhesion Kinase 1; Functional disorder; Goals; Homeostasis; Homo; Impairment; Inflammation; Injury; Integrin Signaling Pathway; Integrin beta Chains; Integrins; Kidney; Kidney Failure; Knockout Mice; Mechanics; Mediating; Mus; Mutant Strains Mice; Pathology; Pathway interactions; Physiology; Process; Recycling; Regulation; Regulatory Pathway; Renal tubule structure; Research; Role; Signal Transduction; Structure; Transforming Growth Factor beta; Transgenic Animals; Tubular formation; Urine; Vasopressins; Water; Work; absorption; apical membrane; aquaporin-2; base; cell injury; cell motility; cell water; collecting tubule structure; fibrogenesis; hemodynamics; integrin-linked kinase; interstitial; kidney fibrosis; mechanotransduction; mortality; nephrogenesis; new therapeutic target; novel; open data; pressure; programs; response; rho GTP-Binding Proteins; trafficking; transcytosis; urinary; water channel

The water channel aquaporin-2 (AQP2) is a major water channel that mediates water transport in the collecting ducts (CDs) of the kidney in response to the antidiuretic hormone (ADH), also called vasopressin (VP). We and others have studied extensively the AQP2 trafficking and its regulatory mechanism(s) for many years. In the past 5 years, our studies have uncovered several important and previously unrecognized aspects of AQP2: 1) AQP2 unexpectedly interacts with the adhesion molecule and major extracellular matrix (ECM) receptor, β1 integrin. Through interaction with β1 integrin, AQP2 modulates the trafficking of β1 integrin and promotes tubular cell migration; 2) Polarized AQP2 trafficking to the apical membrane involves basolateral insertion and redirection via transcytosis, and therefore, is potentially subjected to regulatory cues from the ECM; 3) More recently, we have identified that a major downstream target of the integrin signaling pathway, integrin-linked kinase (ILK) regulates AQP2 recycling via modulating the actin cytoskeleton. These data open a novel aspect of a close interplay of AQP2 trafficking and integrin-ECM signaling, and the importance of their interaction in modulating epithelial structure and function. To understand it further, we generated transgenic animals with a deletion of β1 integrin specifically in the principal cells (PCs) in the kidney collecting ducts. Very interestingly, we have found that deleting β1 integrin in the CD PCs causes significant tubular injury and interstitial fibrosis with significantly activated TGF-β signaling cascade. KO mice develop renal failure and early mortality at 6-8 weeks of age. In addition, the young KO and adult hemizygous KO mice presented with highly concentrated urine and impaired capability of water diuresis. There was a significant and persistent apical membrane accumulation of AQP2 in the CD PCs in the homo- and hemizygous β1 integrin KO mice. Based on these two intriguing observations, we proposed a comprehensive research program to 1) determine the critical function of PC specific β1 integrin signaling in maintaining collecting duct integrity, and dissect specifically, the epithelial mechanism(s) contributing to TGF-β activation and subsequent interstitial fibrosis in the β1 integrin KO animals; and 2) characterize the novel regulatory role of β1 integrin signaling in AQP2 trafficking in cells and urine concentration in the kidney. Our proposed studies are logically integrated and focus on two important processes of acute CD injury/fibrosis and water retention. Cross talk between AQP2 and β1 integrin could, therefore, be involved in mediating both cell injury and water reabsorption. They will contribute importantly to better understanding the fundamentally critical, but overlooked epithelial factors that initiate and promote fibrogenesis in kidney. They will also uncover a novel ECM-integrin mediated regulatory mechanism for water transport in the kidney. It could serve as a local regulator of water homeostasis in response to hemodynamic and volume changes.

水通道水通道蛋白-2 (AQP2) 是介导水收集过程中水运输的主要水通道。 肾脏导管 (CD) 响应抗利尿激素 (ADH)，也称为加压素 (VP)。我们和 其他人多年来对 AQP2 贩运及其调控机制进行了广泛研究。在 过去 5 年，我们的研究揭示了 AQP2 的几个重要且以前未被认识的方面：1) AQP2 意外地与粘附分子和主要细胞外基质 (ECM) 受体 β1 相互作用 整合素。通过与 β1 整合素相互作用，AQP2 调节 β1 整合素的运输并促进 肾小管细胞迁移； 2) 极化 AQP2 运输至顶膜涉及基底外侧插入和 通过转胞吞作用进行重定向，因此可能受到 ECM 的监管提示； 3）更多 最近，我们发现整合素信号通路的一个主要下游靶标，整合素相关的 激酶 (ILK) 通过调节肌动蛋白细胞骨架来调节 AQP2 循环。这些数据开启了一个新的方面 AQP2 运输和整合素-ECM 信号传导的密切相互作用，以及它们相互作用的重要性 调节上皮结构和功能。为了进一步了解它，我们产生了转基因动物 β1 整合素的缺失，特别是在肾集合管的主细胞 (PC) 中。非常有趣的是， 我们发现删除 CD PC 中的 β1 整合素会导致严重的肾小管损伤和间质纤维化 具有显着激活的 TGF-β 信号级联反应。 KO 小鼠在 6-8 岁时出现肾衰竭和早期死亡 周龄。此外，幼年 KO 小鼠和成年半合子 KO 小鼠呈现出高度集中的 尿和水利尿能力受损。有明显且持久的顶膜 纯合子和半合子 β1 整合素 KO 小鼠 CD PC 中 AQP2 的积累。基于这两个 有趣的观察，我们提出了一个全面的研究计划，以 1）确定 PC 特异性 β1 整合素信号传导维持集合管完整性，并具体解剖上皮细胞 β1 整合素 KO 中导致 TGF-β 激活和随后的间质纤维化的机制 动物; 2) 表征 β1 整合素信号在细胞中 AQP2 运输中的新调节作用 肾脏中的尿液浓度。我们提出的研究在逻辑上是综合的，重点关注两个重要的问题 急性 CD 损伤/纤维化和水潴留的过程。 AQP2 和 β1 整合素之间的串扰可以， 因此，参与介导细胞损伤和水重吸收。他们将为 更好地了解启动和促进的基本关键但被忽视的上皮因素 肾脏纤维化。他们还将发现一种新的 ECM 整合素介导的水调节机制 在肾脏中运输。它可以作为水稳态的局部调节剂以响应血流动力学 和音量变化。