Signaling mechanisms that mediate anoxia-induced cellular arrest

建议书摘要 大多数生物体对氧气浓度(O2)的波动高度敏感，它们在氧气浓度上 依靠产生三磷酸腺苷(ATP)，这是细胞的能量来源。氧气剥夺 (缺氧)导致氧化磷酸化减少，ATP相应减少，这 在新陈代谢需求较高的器官，如大脑、心脏和 肾脏。然而，已经有文献证明，一些生物体可以通过一种 程序化转变为“暂停”或低代谢状态，其特征是戏剧性的 通过阻止依赖于三磷酸腺苷的过程减少三磷酸腺苷的消耗。这种情况有一种保护作用 对生物体活性的影响是可逆的，使生物体恢复新陈代谢和生命 一旦氧气恢复。了解如何触发这种低代谢状态可能会有戏剧性的影响 预防缺氧/缺血损伤并促进其存活和储存的后果 供移植的器官。斑马鱼是研究这一规律的杰出模型 新陈代谢不足。根据不同的阶段，暴露在缺氧中的胚胎可能会阻止发育 长达50小时，一旦氧气恢复，就能成功培育出可存活的成虫。这样做的前提是 建议识别触发缺氧诱导停滞的关键信号分子。 斑马鱼胚胎将进一步加深我们对这一过程的理解，并提供治疗靶点 保护患者免受缺氧/缺血损伤。我们假设代谢物乳酸作为一种 细胞信号的减少，并触发代谢停滞通过稳定和转位 N-myc下游调节(NDRG)蛋白，阻止ATP要求的过程。我们将揭晓 乳酸/NDRG1信号通路在低氧适应中的作用：(1)实验 乳酸/NDRG1信号在发育停滞中是否重要，(2)研究 乳酸在NDRG1翻译后调节中的作用，(3)研究乳酸/NDRG1的作用 在阻断Na+K+ATPase泵方面。

PROPOSAL ABSTRACT Most organisms are highly sensitive to fluctuations in the concentration of oxygen (O2), on which they depend to generate adenosine triphosphate (ATP), the cell’s source of energy. O2 deprivation (anoxia) causes a reduction in oxidative phosphorylation and a corresponding decrease in ATP, which is most acutely experienced in organs with high metabolic demand, such as the brain, heart and kidney. However, it has been documented that some organisms can respond to low O2 with a programmed transition into a “suspended” or hypometabolic state, characterized by a dramatic reduction in ATP consumption via arrest of ATP-dependent processes. This condition has a protective effect on organism viability and is reversible, allowing the organism to resume metabolism and life once O2 is restored. Understanding how to trigger such a hypometabolic state could have dramatic consequences for the prevention of hypoxic/ischemic injury and to promote the viability and storage of organs for transplantation. The zebrafish represents an outstanding model for studying the regulation of hypometabolism. Depending on the stage, embryos exposed to anoxia can arrest development for up to 50 hours and then successfully produce viable adults once O2 is restored. The premise of this proposal is that the identification of key signaling molecules that trigger anoxia-induced arrest in the zebrafish embryo will further our understanding of this process and provide therapeutic targets for protecting patients from hypoxic/ischemic injury. We hypothesize that the metabolite lactate acts as a cellular signal for reduced O2, and triggers metabolic arrest through stabilization and translocation of N-myc Downstream Regulated (NDRG) proteins that block ATP-demanding processes. We will reveal the role of lactate/NDRG1 signaling in adaptation to reduced O2 by pursuing three aims: (1) Test whether lactate/NDRG1 signaling is important for developmental arrest, (2) Investigate the role of lactate in post-translational regulation of NDRG1, (3) Investigate the role of lactate/NDRG1 in arresting the Na+K+ATPase pump.