ALDOSE REDUCTASE AND DIABETIC COMPLICATIONS

描述：(调查员摘要)。长期糖尿病导致主要原因 不需要胰岛素转运的组织中的并发症 葡萄糖，包括高血糖引起的神经病变，视网膜病变， 肾病、上皮病和白内障的发生。然而， 高血糖诱导细胞损伤的机制尚不清楚。 多元醇途径的第一种酶，醛糖还原酶(AR)已经被 因使用醛糖还原酶而与糖尿病并发症有关 抑制剂(ARI)可预防、减少或在某种程度上逆转 高血糖导致白内障、神经病变和视网膜病变。 高血糖时AR活性增加归因于激活 和/或酶的诱导。然而，这两种机制都没有 无论是诱导还是激活都是很好的理解。此外，所有的 目前已知的ARIs抑制AR和乙醛还原酶，并且两者 酶具有重叠的底物特性。乙醛还原酶可能 对减少生物胺和一些二羰基很重要 化合物。因此，为了了解和管理糖尿病 并发症，有必要阐明其物理化学 AR的特性及其调节和生理作用，以及 乙醛还原酶的性质。我们建议继续我们的 AR和醛的结构和动力学性质研究 还原酶，以及正常血糖和正常血糖状态下AR的调节。 高血糖状态。我们将测定化学催化剂 这些酶的缩醛机理，它们的缩醛机理 缓蚀剂与底物的相互作用及其序列 底物结合部位。底物和底物中的残留物 抑制物结合，使醛糖还原酶失活和在化学中 反应将通过定点突变进行研究。AR 在高血糖时活性增加，反应动力学和 抑制剂的敏感性也会发生变化。氧化、糖基化和蛋白质合成的作用 将通过诱导来了解激活的机制(S)， 高血糖时AR的失活和转录增加。 我们将使用高血糖动物模型和培养的神经母细胞瘤 以评估氧化应激对组织损伤的贡献， 可能是由于自由基增加和/或防御能力下降所致 抗氧化剂和多元醇的能力。我们的学习将有助于 了解AR在糖尿病并发症病因中的作用， 将提供一种合理的方法来治疗或预防 这种并发症的发展。

DESCRIPTION: (Investigator's Abstract). Prolonged diabetes causes major complications in tissues which do not require insulin for transport of glucose, including hyperglycemia-induced neuropathy, retinopathy, nephropathy, epitheliopathy, and cataractogenesis. However, the mechanisms of hyperglycemia-induced cell injury are poorly understood. The first enzyme of the polyol pathway, aldose reductase (AR), has been implicated in diabetic complications because use of aldose reductase inhibitors (ARIs) prevents, reduces, or, to some extent, reverses hyperglycemia-induced cataractogenesis, neuropathy, and retinopathy. Increased AR activity in hyperglycemia has been attributed to activation and/or induction of the enzyme. However, neither the mechanisms of induction nor of activation are well understood. In addition, all the ARIs presently known inhibit both AR and aldehyde reductase, and both enzymes have overlapping substrate specificities. Aldehyde reductase may be important for reducing biogenic amines and a number of dicarbonyl compounds. Therefore, for understanding and managing diabetic complications, it is necessary to elucidate the physicochemical properties of AR and its regulation and physiological roles, along with the properties of aldehyde reductase. We propose to continue our studies on the structural and kinetic properties of AR and aldehyde reductase, and on the regulation of AR under normo-glycemic and hyperglycemic conditions. We will determine the chemical catalytic mechanisms of aldehyde reduction by these enzymes, their mechanisms of inhibitor and substrate interactions, and the sequences of their substrate binding sites. The residues involved in substrate and inhibitor binding, inactivation of aldose reductase and in the chemical reactions will be studied by using site directed mutagenesis. The AR activity increases in hyperglycemia, and the reaction kinetics and inhibitor sensitivity also change. The roles of oxidation, glycation and induction will be examined to understand the mechanism(s) of activation, deactivation and increased transcription of AR during hyperglycemia. We will use a hyperglycemic animal model and cultured neuroblastoma cells to assess the contributions of oxidative stress to tissue injury, perhaps caused by increased free radicals and/or decreased defense capacity against oxidants and polyols. Our studies will help in understanding the role of AR in the etiology of diabetic complications, and will provide a logical approach to treating or preventing the development of such complications.