Role of guanine nucleotides in ischemic renal injury

鸟嘌呤核苷酸在缺血性肾损伤中的作用

• 批准号: 6640031
• 负责人: Pierre C Dagher
• 金额: $ 21万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6640031
• 关键词: MDCK cell; adenine nucleotides; apoptosis; chimeric proteins; colorimetry; fluorimetry; gene targeting; genetically modified animals; guanine nucleotides; guanosinetriphosphatases; high performance liquid chromatography; hypoxanthine phosphoribosyltransferase; hypoxia; inosine monophosphate; intermolecular interaction; laboratory mouse; molecular pathology; mycophenolic acid; necrosis; renal ischemia /hypoxia; reperfusion; terminal nick end labeling; transfection

DESCRIPTION (provided by applicant): lschemic renal disease remains a major cause of mortality and morbidity in this country. It is an important etiologic factor in many cases of renal failure in patients with vascular disease. While the pathophysiology of ischemic tissue damage is complex and multifactorial, several mediators of injury have been identified. Among these, ATP depletion is generally viewed as the hallmark of acute ischemia in many settings. Indeed, mush has been learned using in vitro models of chemical anoxia- induced ATP depletion in cell culture systems. However, the dynamics of cellular GTP pools during ischemia/reperIusion or chemical anoxia/recovery have not been investigated systematically. Thus, there remains a big gap in our understanding of the role of guanine nucleotide depletion in ischemia. Such a role for guanine nucleotides is suggested by the importance of the cellular GTP/GDP ratio in the functioning of a variety of signaling GTPases that control trafficking, polarity, the cytoskeleton and cell death in epithelia. In particular, the small GTPases Rho, Rac and Cdc42 are emerging as central participants in the injury-repair cycles observed in ischemia/reperfusion. The central hypothesis to be tested in this proposal is that GTP depletion during ischemia/reperfusion is an important and independent variable in determining the form of cell death observed. Apoptosis is increasingly recognized as a significant mode of cell loss during ischemia. Our hypothesis postulates a major role for GTP depletion in modulating this form of cell death, possibly via an effect on Rho family GTPases. We propose to develop models of selective GTP and ATP depletion and correlate them with cell survival and apoptotic death in culture systems. We will also investigate the role of Rho GTPases in modulating apoptosis using cells transfected with constitutively active and dominant negative forms of the GTPases Rho, Rac and Cdc42. Finally, we will examine the role of GTP in renal ischemia in vivo using control and HPRT-null mice that cannot salvage guanosine to GTP. The effects of enhanced GTP levels on morphology, apoptosis and renal function will be determined. These studies will establish GTP as a key . modulator of ischemic injury and might lead to new therapeutic options for this devastating disease.

描述（由申请人提供）：缺血性肾病仍然是这个国家死亡率和发病率的主要原因。它是许多血管疾病患者肾功能衰竭的重要病因。虽然缺血性组织损伤的病理生理是复杂和多因素的，但已经确定了几种损伤介质。其中，在许多情况下，ATP消耗通常被视为急性缺血的标志。事实上，在细胞培养系统中使用体外化学缺氧诱导的ATP耗竭模型已经了解了糊状。然而，在缺血/再灌注或化学缺氧/恢复期间，细胞GTP池的动态尚未得到系统的研究。因此，我们对鸟嘌呤核苷酸耗损在缺血中的作用的理解仍有很大的差距。鸟嘌呤核苷酸的这种作用是由细胞GTP/GDP比值在控制上皮内运输、极性、细胞骨架和细胞死亡的各种信号GTP酶的功能中的重要性所提示的。特别是，小gtpase Rho， Rac和Cdc42在缺血/再灌注中观察到的损伤-修复周期中成为中心参与者。本研究的中心假设是，在缺血/再灌注过程中，GTP耗竭是决定细胞死亡形式的一个重要且独立的变量。细胞凋亡越来越被认为是缺血期间细胞损失的一种重要模式。我们的假设假设GTP消耗在调节这种形式的细胞死亡中起主要作用，可能是通过对Rho家族GTP酶的影响。我们建议建立选择性GTP和ATP消耗模型，并将它们与培养系统中细胞存活和凋亡死亡联系起来。我们还将研究Rho gtpase在调节细胞凋亡中的作用，使用转染了gtpase Rho， Rac和Cdc42的组成型活性和显性阴性形式的细胞。最后，我们将在体内研究GTP在肾缺血中的作用，使用对照组和hprt缺失的小鼠，这些小鼠不能将鸟苷挽救到GTP中。提高GTP水平对形态学、细胞凋亡和肾功能的影响将被确定。这些研究将确定GTP是关键。缺血性损伤的调节剂，并可能为这种毁灭性疾病带来新的治疗选择。