Recovery from acute kidney injury

描述（申请人提供）：急性肾损伤（Acute kidney injury， AKI）是一个巨大的医学问题，在住院患者尤其是ICU患者中发病率和死亡率非常高。治疗仅包括支持性护理，在极端情况下，还包括肾脏替代。我们未能找到有效治疗方法的一个主要因素是，我们对肾如何从AKI中恢复的理解非常有限，因此我们在确定可能的治疗方法和药物方面一直处于不利地位。我们开发了一种创新的新系统来研究AKI的回收，这将使我们能够更好地分析AKI的分子和细胞基础。这将使我们能够识别、测试和完善候选疗法。AKI的主要靶点是上皮细胞，尤其是近端小管细胞。严重的损伤产生死细胞，这些细胞被挤进管状管腔。这项资助的重点是了解小管随后是如何修复的，长期目标是改善修复。我们将检验磷脂酰肌醇3,4-二磷酸（PIP2）和3,4,5-三磷酸（PIP3）在伤口愈合中发挥特定作用的假设。我们将使用活细胞成像来验证PIP3既控制细胞扩散过程中前缘的形成，也控制细胞扩散过程中的细胞高度和伤口愈合结束时的复极化的预测。我们还将验证PIP2控制顶端质膜的大小从而影响细胞形状和扩散的预测。我们将在AKI的体内模型中证实这一点。我们预测合成PIP3的酶的不同同工异构体可能具有不同的功能，例如控制细胞高度或前缘的形成。当小管中的一些细胞死亡时，幸存的细胞部分去极化、去分化、迁移和增殖以覆盖脱落的区域。后来，当幸存的细胞与新邻居接触时，细胞在接触抑制的过程中停止迁移和增殖。我们将测试Ras-Raf-MEK-ERK级联和PAK-PIX复合物两种信号通路在控制分化、迁移和接触抑制中的作用。

DESCRIPTION (provided by applicant): Acute kidney injury (AKI) is an enormous medical problem, with a very high incidence and mortality rate in hospitalized patients, especially in the ICU. Treatment consists solely of supportive care and, in extreme cases, renal replacement. A major factor in our failure to find effective therapy is that our understanding of how the kidney recovers from AKI is very limited and so we have been handicapped in identification of possible approaches and drugs for therapy. We have developed an innovative new system to study the recovery from AKI, which will allow us to better analyze the molecular and cellular basis of this process from AKI. This will in turn allow us to identify, test and refine candidate therapies. A major target in AKI is the epithelium, especially proximal tubule cells. Severe insults produce dead cells, which are extruded into the tubular lumen. The focus of this grant is to understand how the tubule is subsequently repaired, with the long term goal of improving repair. We will test the hypothesis that phosphatidylinositols 3,4-bisphosphate (PIP2) and 3,4,5-trisphosphate (PIP3) play specific roles in wound healing. We will use live cell imaging to test the prediction that PIP3 controls both formation of the leading edge during cell spreading, as well as cell height during cell spreading and repolarization at the end of wound healing. We will also test the prediction that PIP2 controls the size of the apical plasma membrane and thereby influences cell shape and spreading. We will confirm this in an in vivo model of AKI. We predict that different isoforms of the enzyme that synthesizes PIP3 may have distinct functions, such as in controlling cell height or formation of the leading edge. When some cells in the tubule die, the surviving cells partially depolarize, dedifferentiate, migrate and proliferate to cover the denuded areas. Later, as the surviving cells make contact with their new neighbors, the cells stop migration and proliferation in the process of contact inhibition. We will test the roles of two signaling pathways, Ras-Raf-MEK-ERK cascade and the PAK-PIX complex, in control of differentiation, migration and contact inhibition.