Defining the Translational Machinery Controlling Hypoxic Sensitivity

动物细胞需要氧气才能生存；没有氧气，几乎所有的动物细胞最终都会死亡。神经元特别是 对缺氧性损伤敏感，中风的破坏证明了这一点。然而，各种动物和细胞 它们相对耐缺氧，但它们在缺氧中生存的机制尚不清楚。 某些动物在严重的低氧环境中冬眠，但以正常的行为退出冬眠 生理上的，没有神经元死亡的证据。在这些化合物中发现了对蛋白质翻译的强烈抑制 冬眠动物，对它们的耐低氧能力很重要。癌细胞通常相对较低。 抵抗力强，翻译机器不规范。综合这些观测结果的流行模型 翻译可以降低能量消耗，从而提高低氧存活率。蛋白质翻译 占能量消耗的很大一部分，细胞通过抑制翻译来应对缺氧。 然而，低氧诱导的翻译抑制并不统一，一些低氧保护蛋白是 在低氧条件下优先翻译。因此，流行的“能量学”模型肯定是过头了。 简单化了，也许是完全不正确的。我们的实验室已经对线虫的基因进行了筛选 控制低氧生存。这些基因中的许多都编码翻译因子。与能量学一致 在模型中，这些低氧保护性突变/RNA会减少整体蛋白质合成和氧气消耗。 然而，转化率和耗氧量的降低程度与水平无关 耐低氧能力强。此外，我们还表明，敲除一个翻译因子rars-1在以下情况下是有保护作用的 在低氧恢复期间启动，此时保存能量不再重要。这些 观察表明，翻译抑制通过复杂的机制保护缺氧，而不是简单的 降低能源消耗。我们建议使用线虫中强大的遗传工具来了解 翻译机器控制低氧生存的复杂机制。我们假设 减少信使核糖核酸翻译的生理后果取决于这种减少是如何实现的。 我们将确定产生耐缺氧的生产途径，并研究其机制。 因此，他们通过以下具体目标来确定低氧生存。目标1：定义路径 翻译机械由此调节缺氧性损伤。我们将识别翻译中的突变 产生耐低氧能力的机械基因，并将识别阻止基因突变 这些翻译突变体的耐低氧性。这些基因将被放置在通路中，它们的作用 翻译上的突变将被确定。目标2：测定代谢和生理指标 翻译机械调节与耐低氧相关的后果。通过这些 目的我们将对翻译机器如何控制缺氧有一个更全面的理解 这台机器的生存和调整的后果。

Animal cells need oxygen for survival; without it virtually all animal cells eventually die. Neurons are particularly sensitive to hypoxic injury as evidenced by the devastation in stroke. However, a variety of animals and cells are relatively hypoxia resistant, but the mechanisms whereby they survive hypoxia are poorly understood. Certain animals hibernate in severe hypoxic environments yet exit from hibernation with normal behavior and physiology and no evidence of neuronal death. Strong suppression of protein translation is found in these hibernating animals and is important to their hypoxia resistance. Cancer cells are often relatively hypoxia resistant and have dysregulated translation machinery. The prevailing model to synthesize these observations is that translation lowers energy consumption and thereby increases hypoxic survival. Protein translation accounts for a large fraction of energy consumption, and cells respond to hypoxia by suppressing translation. However, hypoxia-induced translational suppression is not uniform, and some hypoxia-protective proteins are preferentially translated under hypoxic conditions. Thus, the prevailing “energetics” model is certainly overly simplistic and perhaps entirely incorrect. Our lab has performed screens in the nematode C. elegans for genes controlling hypoxic survival. Many of these genes encode translation factors. Consistent with energetics models, these hypoxia protective mutations/RNAis reduce overall protein synthesis and oxygen consumption. However, the degree of reduction in translation rate and oxygen consumption does not correlate with the level of hypoxia resistance. Further, we showed that knockdown of one translation factor, rars-1, is protective when initiated during recovery from hypoxia when energy preservation should no longer be important. These observations suggest that translational suppression protects from hypoxia by complex mechanisms, not simply lowering energy consumption. We propose using the powerful genetic tools in C. elegans to understand the complex mechanism whereby the translation machinery controls hypoxic survival. We hypothesize that the physiological consequences of reducing mRNA translation vary depending on how this reduction is achieved. We will identify productive pathways that can produce resistance to hypoxia and study the mechanisms whereby they determine hypoxic survival through the following specific aims. Aim1: Define pathways whereby translation machinery regulates hypoxic injury. We will identify mutations in translation machinery genes that produce hypoxia resistance and will also identify mutations in genes that block the hypoxia resistance in these translation mutants. These genes will be placed in pathways and the effect of their mutations on translation will be determined. Aim 2: Determine the metabolic and physiological consequences of translation machinery modulation associated with hypoxia resistance. Through these aims we will develop a more complete understanding of how the translation machinery controls hypoxic survival and the consequences of the modulation of this machinery.