Chong Zhao Zhong, Li Faqi, Maiese Kenneth
Department of Neurology, 8C-1 UHC, Wayne State University School of Medicine, 4201 St. Antoine, Detroit, MI 48201, USA.
Curr Neurovasc Res. 2005 Dec;2(5):387-99. doi: 10.2174/156720205774962683.
No longer considered exclusive for the function of the hematopoietic system, erythropoietin (EPO) is now considered as a viable agent to address central nervous system injury in a variety of cellular systems that involve neuronal, vascular, and inflammatory cells. Yet, it remains unclear whether the protective capacity of EPO may be effective for chronic neurodegenerative disorders such as Alzheimer's disease (AD) that involve beta-amyloid (Abeta) apoptotic injury to hippocampal neurons. We therefore investigated whether EPO could prevent both early and late apoptotic injury during Abeta exposure in primary hippocampal neurons and assessed potential cellular pathways responsible for this protection. Primary hippocampal neuronal injury was evaluated by trypan blue dye exclusion, DNA fragmentation, membrane phosphatidylserine (PS) exposure, and nuclear factor-kappaB (NF-kappaB) expression with subcellular translocation. We show that EPO, in a concentration specific manner, is able to prevent the loss of both apoptotic genomic DNA integrity and cellular membrane asymmetry during Abeta exposure. This blockade of Abeta generated neuronal apoptosis by EPO is both necessary and sufficient, since protection by EPO is completely abolished by co-treatment with an anti-EPO neutralizing antibody. Furthermore, neuroprotection by EPO is closely linked to the expression of NF-kappaB p65 by preventing the degradation of this protein by Abeta and fostering the subcellular translocation of NF-kappaB p65 from the cytoplasm to the nucleus to allow the initiation of an anti-apoptotic program. In addition, EPO intimately relies upon NF-kappaB p65 to promote neuronal survival, since gene silencing of NF-kappaB p65 by RNA interference removes the protective capacity of EPO during Abeta exposure. Our work illustrates that EPO is an effective entity at the neuronal cellular level against Abeta toxicity and requires the close modulation of the NF-kappaB p65 pathway, suggesting that either EPO or NF-kappaB may be used as future potential therapeutic strategies for the management of chronic neurodegenerative disorders, such as AD.
促红细胞生成素（EPO）不再被认为仅具有造血系统功能，现在它被视为一种可行的药物，可用于多种涉及神经元、血管和炎症细胞的细胞系统中治疗中枢神经系统损伤。然而，EPO的保护能力对于诸如阿尔茨海默病（AD）这类涉及β-淀粉样蛋白（Aβ）对海马神经元凋亡性损伤的慢性神经退行性疾病是否有效仍不清楚。因此，我们研究了EPO是否能预防原代海马神经元在Aβ暴露期间的早期和晚期凋亡性损伤，并评估了负责这种保护作用的潜在细胞途径。通过台盼蓝染料排除法、DNA片段化、膜磷脂酰丝氨酸（PS）暴露以及核因子-κB（NF-κB）表达及其亚细胞转位来评估原代海马神经元损伤。我们发现，EPO能够以浓度特异性的方式，在Aβ暴露期间预防凋亡基因组DNA完整性的丧失和细胞膜不对称性的破坏。EPO对Aβ诱导的神经元凋亡的这种阻断作用既是必要的也是充分的，因为与抗EPO中和抗体共同处理会完全消除EPO的保护作用。此外，EPO的神经保护作用与NF-κB p65的表达密切相关，它通过防止Aβ降解该蛋白并促进NF-κB p65从细胞质向细胞核的亚细胞转位，从而启动抗凋亡程序。此外，EPO紧密依赖NF-κB p65来促进神经元存活，因为通过RNA干扰使NF-κB p65基因沉默会消除EPO在Aβ暴露期间的保护能力。我们的研究表明，EPO在神经元细胞水平上是对抗Aβ毒性的有效物质，并且需要对NF-κB p65途径进行密切调节，这表明EPO或NF-κB都可能作为未来治疗慢性神经退行性疾病（如AD）的潜在治疗策略。
