Musiek Erik S, Breeding Rebecca S, Milne Ginger L, Zanoni Giuseppe, Morrow Jason D, McLaughlin Bethann
Department of Pharmacology, Venderbilt University, Nashville, Tennessee 37232, USA.
J Neurochem. 2006 Jun;97(5):1301-13. doi: 10.1111/j.1471-4159.2006.03797.x. Epub 2006 Apr 21.
Oxidative stress and subsequent lipid peroxidation are involved in the pathogenesis of numerous neurodegenerative conditions, including stroke. Cyclopentenone isoprostanes (IsoPs) are novel electrophilic lipid peroxidation products formed under conditions of oxidative stress via the isoprostane pathway. These cyclopentenone IsoPs are isomeric to highly bioactive cyclopentenone prostaglandins, yet it has not been determined if these products are biologically active or are formed in the brain. Here we demonstrate that the major cyclopentenone IsoP isomer 15-A2t-IsoP potently induces apoptosis in neuronal cultures at submicromolar concentrations. We present a model in which 15-A2t-IsoP induced neuronal apoptosis involves initial depletion of glutathione and enhanced production of reactive oxygen species, followed by 12-lipoxygenase activation and phosphorylation of extracellular signal-regulated kinase 1/2 and the redox sensitive adaptor protein p66shc, which results in caspase-3 cleavage. 15-A2t-IsoP application also dramatically potentiates oxidative glutamate toxicity at concentrations as low as 100 nm, demonstrating the functional importance of these molecules in neurodegeneration. Finally, we employ novel mass spectrometric methods to show that cyclopentenone IsoPs are formed abundantly in brain tissue under conditions of oxidative stress. Together these findings suggest that cyclopentenone IsoPs may contribute to neuronal death caused by oxidative insults, and that their activity should perhaps be addressed when designing neuroprotective therapies.
氧化应激及随后的脂质过氧化参与了包括中风在内的多种神经退行性疾病的发病机制。环戊烯酮异前列腺素（IsoPs）是在氧化应激条件下通过异前列腺素途径形成的新型亲电子脂质过氧化产物。这些环戊烯酮IsoPs与具有高度生物活性的环戊烯酮前列腺素是同分异构体，但尚未确定这些产物是否具有生物活性或是否在大脑中形成。在此，我们证明主要的环戊烯酮IsoP异构体15-A2t-IsoP在亚微摩尔浓度下能有效诱导神经元培养物中的细胞凋亡。我们提出了一个模型，其中15-A2t-IsoP诱导的神经元凋亡涉及谷胱甘肽的初始消耗和活性氧的产生增加，随后是12-脂氧合酶的激活以及细胞外信号调节激酶1/2和氧化还原敏感衔接蛋白p66shc的磷酸化，这导致半胱天冬酶-3的裂解。15-A2t-IsoP的应用在低至100 nM的浓度下也能显著增强氧化型谷氨酸的毒性，证明了这些分子在神经退行性变中的功能重要性。最后，我们采用新型质谱方法表明，在氧化应激条件下，环戊烯酮IsoPs在脑组织中大量形成。这些发现共同表明，环戊烯酮IsoPs可能导致氧化损伤引起的神经元死亡，并且在设计神经保护疗法时或许应考虑它们的活性。
