Chaperone therapeutics for the treatment of DPN

描述(申请人提供)：糖尿病周围神经病变(DPN)的病因学起源于一系列相互关联的代谢和血管损害，最终导致 感觉神经元的退化。在寻求药理学管理DPN的过程中，小分子抑制剂已经被开发出来，以靶向被认为是“糖尿病特异性”的蛋白质以及那些在多种疾病状态下增加的蛋白质。这些努力还没有被证明是成功的，这表明识别在调节蛋白质完整性和保护糖尿病状态下的神经功能方面发挥基础作用的新靶点可能代表着一种新的范式。热休克蛋白90(Hsp90)是一种分子伴侣，能结合“客户蛋白”并促进其折叠成生物活性结构。它也是细胞保护性“热休克反应”的主要调节者，热休克反应帮助细胞应激时聚集和受损的蛋白质重新折叠。Hsp90的N端和C端的ATP结合域都调节其与蛋白质的相互作用。Hsp90的N-端抑制剂对肿瘤细胞表现出很强的细胞毒性，正在进行临床试验，但这些化合物也在细胞毒性所需的浓度下诱导细胞保护性“热休克反应”。相反，我们已经开发出了Hsp90C-末端结构域的有效小分子抑制剂，其神经保护效果的浓度远远低于诱导神经毒性所需的浓度。这些抑制剂的先导化合物KU-32是以新霉素为基础的。KU-32可保护高血糖诱导的感觉神经元死亡，并可通过诱导热休克反应来减轻DPN的几个生理指标。不幸的是，这种分子需要大量的合成准备，从而阻碍了结构-活性关系的充分阐明，并限制了它在动物/人类中的使用。因此，本提案的目标是提供从KU-32衍生的新化合物，这些化合物显示出更好的神经保护活性，并且可以在最少的合成步骤中制备。初步筛选将确定与KU-32相比具有更高有效性的化合物，并将测试候选铅对感觉神经元的血糖压力的保护作用，随后将在野生型和Hsp70基因敲除小鼠中进行DPN的动物研究。这项工作的结果将进一步开发和鉴定小分子Hsp90抑制剂，在没有明显神经毒性的情况下减少神经变性。 公共卫生相关性：糖尿病神经病变是糖尿病的一种常见并发症，在约2400万美国糖尿病患者中，约60%会发生这种并发症。尽管糖尿病神经病变会降低生活质量，但FDA批准的现有治疗方法仅限于最初针对抑郁症(Cymbalta)和抽搐(Lyrica)的药物。该项目专注于优化一种新的治疗方法直接治疗糖尿病神经病变的有效性。

DESCRIPTION (provided by applicant): The etiology of diabetic peripheral neuropathy (DPN) initiates from an inter-related series of metabolic and vascular insults that ultimately contribute to sensory neuron degeneration. In the quest to pharmacologically manage DPN, small molecule inhibitors have been developed to target proteins regarded as "diabetes specific" as well as those that increase in multiple disease states. Such efforts have not proven successful suggesting the identification of novel targets that play a fundamental role in regulating protein integrity and preserving nerve function in the diabetic state may represent a new paradigm. Heat shock protein 90 (Hsp90) is a molecular chaperone that binds "client proteins" and promotes their folding into biologically active structures. It is also the master regulator of a cytoprotective "heat shock response", which aids the refolding of aggregated and damaged proteins that occur upon cell stress. Both the N- and C-terminal ATP binding domains of Hsp90 regulate its interaction with proteins. N-terminal inhibitors of Hsp90 exhibit potent cytotoxicity against tumor cells and are in clinical trials, but these compounds also induce a cytoprotective "heat shock response" at concentrations necessary for cytotoxicity. In contrast, we have developed potent small molecule inhibitors of the Hsp90 C-terminal domain whose neuroprotective efficacy is manifested at concentrations far below those necessary to induce neuro-toxicity. The lead compound for these inhibitors, KU- 32, is based upon novobiocin. KU-32 protects against hyperglycemia-induced death of sensory neurons and can attenuate several physiologic indices of DPN in mice through induction of the heat shock response. Unfortunately, this molecule requires significant synthetic preparation, thus preventing full elucidation of structure-activity relationships and limiting its use in animals/humans. Thus, the goal of this proposal is to provide new compounds derived from KU-32 that exhibit better neuroprotective activity and can be prepared in a minimal number of synthetic procedures. An initial screen will identify compounds with increased efficacy relative to KU-32 and lead candidates will be tested for protection against glycemic stress of sensory neurons, followed by animal studies of DPN in both wild-type and Hsp70 knockout mice. The outcome of this work will further develop and identify small molecule C-terminal Hsp90 inhibitors that decrease neurodegeneration in the absence of significant neurotoxicity. PUBLIC HEALTH RELEVANCE: Diabetic neuropathy is a common complication of diabetes that develops in about 60% of the approximately 24 million Americans afflicted with diabetes. Despite the impact of diabetic neuropathy on decreasing the quality of life, the existing FDA approved treatments are limited to drugs originally targeted to treat depression (Cymbalta) and convulsions (Lyrica). This project focuses on optimizing the effectiveness of a new class of therapeutics for the direct treatment of diabetic neuropathy.