Lee Donna W, Rajagopalan Subramanian, Siddiq Ambreena, Gwiazda Roberto, Yang Lichuan, Beal M Flint, Ratan Rajiv R, Andersen Julie K
Buck Institute for Age Research, Novato, California 94945, USA.
J Biol Chem. 2009 Oct 16;284(42):29065-76. doi: 10.1074/jbc.M109.000638. Epub 2009 Aug 13.
Hypoxia-inducible factor (HIF) plays an important role in cell survival by regulating iron, antioxidant defense, and mitochondrial function. Pharmacological inhibitors of the iron-dependent enzyme class prolyl hydroxylases (PHD), which target alpha subunits of HIF proteins for degradation, have recently been demonstrated to alleviate neurodegeneration associated with stroke and hypoxic-ischemic injuries. Here we report that inhibition of PHD by 3,4-dihydroxybenzoate (DHB) protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigral dopaminergic cell loss and up-regulates HIF-1alpha within these neurons. Elevations in mRNA and protein levels of HIF-dependent genes heme oxygenase-1 (Ho-1) and manganese superoxide dismutase (Mnsod) following DHB pretreatment alone are also maintained in the presence of MPTP. MPTP-induced reductions in ferroportin and elevations in nigral and striatal iron levels were reverted to levels comparable with that of untreated controls with DHB pretreatment. Reductions in pyruvate dehydrogenase mRNA and activity resulting from MPTP were also found to be attenuated by DHB. In vitro, the HIF pathway was activated in N27 cells grown at 3% oxygen treated with either PHD inhibitors or an iron chelator. Concordant with our in vivo data, the MPP(+)-elicited increase in total iron as well as decreases in cell viability were attenuated in the presence of DHB. Taken together, these data suggest that protection against MPTP neurotoxicity may be mediated by alterations in iron homeostasis and defense against oxidative stress and mitochondrial dysfunction brought about by cellular HIF-1alpha induction. This study provides novel data extending the possible therapeutic utility of HIF induction to a Parkinson disease model of neurodegeneration, which may prove beneficial not only in this disorder itself but also in other diseases associated with metal-induced oxidative stress.
缺氧诱导因子（HIF）通过调节铁、抗氧化防御和线粒体功能在细胞存活中发挥重要作用。铁依赖性酶脯氨酰羟化酶（PHD）的药理抑制剂可靶向HIF蛋白的α亚基进行降解，最近已证明其可减轻与中风和缺氧缺血性损伤相关的神经退行性变。在此，我们报告3,4 - 二羟基苯甲酸（DHB）对PHD的抑制作用可保护免受1 - 甲基 - 4 - 苯基 - 1,2,3,6 - 四氢吡啶（MPTP）诱导的黑质多巴胺能细胞损失，并上调这些神经元内的HIF - 1α。单独使用DHB预处理后，HIF依赖性基因血红素加氧酶 - 1（Ho - 1）和锰超氧化物歧化酶（Mnsod）的mRNA和蛋白质水平升高，在存在MPTP的情况下也能维持。MPTP诱导的铁转运蛋白减少以及黑质和纹状体铁水平升高，通过DHB预处理可恢复到与未处理对照相当的水平。还发现DHB可减轻MPTP导致的丙酮酸脱氢酶mRNA和活性降低。在体外，在用PHD抑制剂或铁螯合剂处理的3%氧气条件下生长的N27细胞中，HIF途径被激活。与我们的体内数据一致，在存在DHB的情况下，MPP⁺引起的总铁增加以及细胞活力降低均得到缓解。综上所述，这些数据表明，对MPTP神经毒性的保护作用可能是由铁稳态的改变以及细胞HIF - 1α诱导所带来的对氧化应激和线粒体功能障碍的防御介导的。本研究提供了新的数据，将HIF诱导的可能治疗效用扩展到帕金森病神经退行性变模型，这不仅可能对该疾病本身有益，而且对其他与金属诱导的氧化应激相关的疾病也可能有益。
