Department of Physiology, Yong Loo Lin School Medicine, National University of Singapore, 117597, Singapore; School of Biomedical Sciences, The University of Queensland, St Lucia, QLD 4072, Australia.
School of Pharmacy, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
Neurobiol Dis. 2014 Feb;62:286-95. doi: 10.1016/j.nbd.2013.10.009. Epub 2013 Oct 16.
Recent findings suggest that Notch-1 signaling contributes to neuronal death in ischemic stroke, but the underlying mechanisms are unknown. Hypoxia inducible factor-1α (HIF-1α), a global regulator of cellular responses to hypoxia, can interact with Notch and modulate its signaling during hypoxic stress. Here we show that Notch signaling interacts with the HIF-1α pathway in the process of ischemic neuronal death. We found that a chemical inhibitor of the Notch-activating enzyme, γ-secretase, and a HIF-1α inhibitor, protect cultured cortical neurons against ischemic stress, and combined inhibition of Notch-1 and HIF-1α further decreased neuronal death. HIF-1α and Notch intracellular domain (NICD) are co-expressed in the neuronal nucleus, and co-immunoprecipitated in cultured neurons and in brain tissue from mice subjected to focal ischemic stroke. Overexpression of NICD and HIF-1α in cultured human neural cells enhanced cell death under ischemia-like conditions, and a HIF-1α inhibitor rescued the cells. RNA interference-mediated depletion of endogenous NICD and HIF-1α also decreased cell death under ischemia-like conditions. Finally, mice treated with inhibitors of γ-secretase and HIF-1α exhibited improved outcome after focal ischemic stroke, with combined treatment being superior to individual treatments. Additional findings suggest that the NICD and HIF-1α collaborate to engage pro-inflammatory and apoptotic signaling pathways in stroke.
最近的研究结果表明，Notch-1 信号通路参与了缺血性中风引起的神经元死亡，但具体的机制尚不清楚。缺氧诱导因子-1α（HIF-1α）作为一种细胞对缺氧反应的全局调节剂，可以与 Notch 相互作用，并在缺氧应激时调节其信号通路。本研究表明，Notch 信号通路在缺血性神经元死亡过程中与 HIF-1α 通路相互作用。我们发现，Notch 激活酶γ-分泌酶的化学抑制剂和 HIF-1α 抑制剂均可保护培养的皮质神经元免受缺血应激的影响，而 Notch-1 和 HIF-1α 的联合抑制则进一步降低了神经元的死亡。在培养的神经元和局灶性缺血性中风小鼠的脑组织中，HIF-1α 和 Notch 细胞内结构域（NICD）共同表达，并发生共免疫沉淀。在类似缺血的条件下，培养的人神经细胞中 NICD 和 HIF-1α 的过表达增强了细胞死亡，而 HIF-1α 抑制剂可挽救这些细胞。类似缺血的条件下，用 RNA 干扰介导的内源性 NICD 和 HIF-1α 耗竭也可减少细胞死亡。最后，用 Notch 激活酶和 HIF-1α 的抑制剂处理的小鼠在局灶性缺血性中风后表现出更好的预后，联合治疗优于单独治疗。进一步的研究结果表明，NICD 和 HIF-1α 共同作用，参与了中风中的促炎和凋亡信号通路。
