NEUROPROTECTIVE GENE INDUCTION BY ANTIOXIDANT IRON CHELA

抗氧化剂铁螯合物诱导神经保护基因

基本信息

批准号：
2911176
负责人：
RAJIV R RATAN
金额：
$ 25.89万
依托单位：
BETH ISRAEL DEACONESS MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
1999
资助国家：
美国
起止时间：
1999-07-15 至 2003-06-30
项目状态：
已结题

项目摘要

Iron chelators are pluripotent neuronal anti-apoptotic agents which have been shown to slow clinical progression in Alzheimer's Disease and enhanced metabolic recovery in cerebral ischemia models. The precise mechanism(s) by which these agents exert their salutary effects remains unclear. In preliminary studies, we have found that structurally distinct iron chelators, deferoxamine mesylate, and mimosine prevent apoptosis induced by glutathione-depletion and oxidative stress in embryonic cortical neurons. We correlated the protective effects of iron chelators with their ability to increase protein expression and enzyme activity of two glycolytic enzymes, lactate dehydrogenase (LDH) and aldolase. The increase in glycolytic enzyme activity induced by iron chelators could be abrogated by actinomycin-D, an mRNA synthase inhibitor, suggesting that the induction is partly transcriptional. consistent with these findings, we demonstrated that iron chelators enhance DNA-binding of two transcription factor complexes, hypoxia- inducible factor-1 (HIF-1) and ATF-1/CREB, in cortical cultures as well as in H19-7 neuronal cell line. Finally, we have shown that message levels for LDH and erythropoietin, genes whose expression is known to be regulated by HIF-1, were elevated in cortical cultures. in response to iron chelator treatment. These preliminary results suggests the following overall hypothesis: iron chelators exert their pluripotent neuroprotective effects, in part by activating a signal transduction pathway that leads to increased expression of genes (e.g., glycolytic enzymes, the growth factor, erythropoietin, or the antioxidant, heme oxygenase) known to compensate for hypoxic or oxidative stress. We propose to test this hypothesis by: 1) determining whether iron chelators enhance heterodimeric HIV-1 (HIF-1 alpha + HIF-1 beta) and/or ATF-1/CREB DNA binding by decreasing peroxide levels; 2) determining the HIF-1 regulated genes induced by iron chelators in embryonic cortical neurons; 3) determining whether enforced expression of HIF-1alpha, HIF- 1beta, ATF-1, or CREB is sufficient for protection from oxidative stress-induced apoptosis; and 4) determining whether HIF-1 is necessary for protection from oxidative stress-induced apoptosis by iron chelators. These studies will define whether HIF-1 is a viable molecular target for therapy of neurological diseases that have been associated with oxidative stress and apoptosis including stroke, Alzheimer's Disease, Parkinson's Disease, and Fredrich's Ataxia. Furthermore, these studies also promise to further define mechanisms of protection by small molecule iron chelators.

铁螯合剂是多能神经元抗凋亡剂，已被证明可以减缓阿尔茨海默病的临床进展并增强脑缺血模型的代谢恢复。这些药物发挥其有益作用的确切机制仍不清楚。在初步研究中，我们发现结构不同的铁螯合剂、甲磺酸去铁胺和含羞草碱可防止胚胎皮质神经元谷胱甘肽耗尽和氧化应激诱导的细胞凋亡。我们将铁螯合剂的保护作用与其增加两种糖酵解酶（乳酸脱氢酶（LDH）和醛缩酶）的蛋白质表达和酶活性的能力相关联。铁螯合剂诱导的糖酵解酶活性的增加可以被放线菌素-D（一种 mRNA 合酶抑制剂）消除，表明这种诱导部分是转录性的。与这些发现一致，我们证明铁螯合剂增强了皮层培养物以及 H19-7 神经元细胞中两种转录因子复合物缺氧诱导因子 1 (HIF-1) 和 ATF-1/CREB 的 DNA 结合线。最后，我们发现 LDH 和促红细胞生成素（已知其表达受 HIF-1 调节）的信息水平在皮质培养物中升高。响应铁螯合剂治疗。这些初步结果表明了以下总体假设：铁螯合剂发挥其多能神经保护作用，部分是通过激活导致基因表达增加的信号转导途径（例如糖酵解酶、生长因子、促红细胞生成素或抗氧化剂、血红素加氧酶））已知可以补偿缺氧或氧化应激。我们建议通过以下方式检验这一假设：1) 确定铁螯合剂是否通过降低过氧化物水平来增强异二聚体 HIV-1 (HIF-1 α + HIF-1 β) 和/或 ATF-1/CREB DNA 结合； 2)确定铁螯合剂在胚胎皮质神经元中诱导的HIF-1调控基因； 3)确定HIF-1α、HIF-1β、ATF-1或CREB的强制表达是否足以防止氧化应激诱导的细胞凋亡； 4) 确定 HIF-1 是否是防止铁螯合剂氧化应激诱导的细胞凋亡所必需的。这些研究将确定 HIF-1 是否是治疗与氧化应激和细胞凋亡相关的神经系统疾病的可行分子靶点，包括中风、阿尔茨海默病、帕金森病和弗雷德里希共济失调。此外，这些研究还有望进一步明确小分子铁螯合剂的保护机制。