Tonicity signaling to TonEBP transcription factor

描述(由申请人提供)： 摘要 转录激活剂TONEBP对肾髓质的发育和功能是必不可少的。在高渗性(高渗盐度)的激活下，TONEBP通过刺激水通道蛋白2和UT-A尿素转运蛋白的转录，对尿药浓度起着关键的调节作用。此外，TONEBP是主要的调节因子，通过刺激细胞内有机渗透压和分子伴侣的积累，保护肾髓质细胞免受高渗和尿素的有害影响。肾脏TONEBP缺陷的转基因小鼠由于大量细胞死亡而表现出严重的骨髓萎缩，以及由于浓缩尿液的能力受损而危及生命的体积耗竭。在患者中，TONEBP与糖尿病肾病、炎症和癌症转移等疾病有关。尽管TONEBP在健康和疾病中很重要，但人们对紧张度的变化是如何识别的以及信息是如何传达给TONEBP的了解很少。我们在前一个时期获得的数据揭示了TONEBP本身是一个音调传感器，它控制着核运输，以响应环境音调的变化。数据还表明，TONEBP是与乙酰基和小泛素样修饰物(SUMO)共价修饰的，以响应高张力。在这项提案中，我们将继续这些令人兴奋的发现，以在分子水平上理解细胞信号对TONEBP的影响。我们将探索高张力信号的两种模型。固有模型指出，TONEBP本身是色调传感器(目标1)。外在模型指出，传感器通过涉及乙酰基和相扑的翻译后修饰向TONEBP发出信号(目标2和目标3)。在目标1中，我们将通过研究TONEBP的核定位信号与执行核输入的细胞机械之间相互作用的紧张度响应变化来揭示紧张度感知的分子基础。目的2是了解组蛋白脱乙酰基酶SIRT1如何以一种紧张性反应的方式控制TONEBP的核输出。将描绘乙酰化和低渗性调节的位置。目标3是通过检测转录抑制和蛋白质稳定性来了解相扑结合如何调节TONEBP的活性。依赖张力的相扑修饰的细胞机制将被描绘出来。 项目叙事 拟议中的研究可能会从根本上揭示关于TONEBP分子是如何被控制的-打开或关闭-的新信息。这一信息将为糖尿病肾病和急性肾功能衰竭等肾脏疾病的治疗提供新的机会。

DESCRIPTION (provided by applicant): Abstract The transcriptional activator TonEBP is essential for the development and function of the renal medulla. Activated by hypertonicity (hyperosmotic salinity), TonEBP is a key regulator for the urinary concentration via stimulating transcription of aquaporin-2 water channel and UT-A urea transporters. In addition, TonEBP is the master regulator for protecting the renal medullary cells from the deleterious effects of hypertonicity and urea via stimulating cellular accumulation of organic osmolytes and molecular chaperone. Genetically modified mice deficient in the renal TonEBP display severe medullary atrophy due to massive cell death, and life threatening volume depletion due to impaired ability to concentrate the urine. In patients, TonEBP is implicated in diseases including diabetic nephropathy, inflammation, and cancer metastasis. Despite the importance of TonEBP in health and disease, little is understood how changes in tonicity is recognized and the information is conveyed to TonEBP. Our data obtained in the previous period reveal clues that TonEBP itself is a tonicity sensor that controls the nuclear trafficking in response to changes in ambient tonicity. The data also demonstrate that TonEBP is covalently modified with acetyl groups and small ubiquitin-like modifiers (SUMO) in response to hypertonicity. In this proposal, we will pursue these exciting findings to understand the cellular signaling to TonEBP at the molecular level. We will explore two models of hypertonicity signaling. The intrinsic model states that TonEBP itself is a tonicity sensor (Aim 1). The extrinsic model states that a sensor signals to TonEBP via posttranslational modifications involving acetyl group and SUMO (Aim 2 and Aim 3). In Aim 1, we will uncover molecular basis of the tonicity sensing by investigating tonicity-responsive changes in the interaction between the nuclear localization signal of TonEBP and the cellular machinery carrying out the nuclear import. Aim 2 is to understand how the histone deaceytlase SIRT1 control the nuclear export of TonEBP in a tonicity-responsive manner. Sites of acetylation and regulation by hypotonicity will be delineated. Aim 3 is to understand how SUMO conjugation modulates the activity of TonEBP by examining transcriptional repression and protein stability. Cellular mechanism of the tonicity-dependent SUMO modification will be delineated. Project Narrative The proposed studies are likely to uncover fundamentally new information about how the TonEBP molecule is controlled -turned on or off. This information will provide new opportunity to develop therapy for renal diseases such as diabetic nephropathy and acute renal failure.