DOES REDUCED GLUTATHIONE PEROXIDASE 4 INCREASE LIFE SPAN BY ALTERING APOPTOSIS

当前计划项目中的项目3的主要观察是小鼠的谷胱甘肽杂合子 与野生型(WT)小鼠相比，过氧化物酶4(Gpx4)具有显著的延长寿命的作用。这一增长 尽管Gpx4/-小鼠在整个生命周期中所有组织中Gpx4的表达都降低了，但还是发生了 寿命；来自Gpx4/-小鼠的胚胎成纤维细胞和肝脏对氧化应激表现出更高的敏感性； Gpx4/-小鼠组织中的氧化损伤水平没有明显变化。 我们认为Gpx4/-小鼠模型是研究衰老机制的有价值的新模型。 因为这些小鼠寿命的延长似乎是通过一种新的途径发生的。例如, 没有证据表明这些小鼠寿命的延长是由于对 氧化应激/氧化损伤减少或来自胰岛素/胰岛素样生长因子-L信号的改变，两条途径 与无脊椎动物和啮齿动物的寿命延长有关。我们假设Gpx4减少 基因的表达通过改变线粒体途径来延长寿命 导致细胞对诱导凋亡的敏感性增加，并增强了 将受损细胞从生物体中移除。如果我们在这个项目中证实了我们的假设，这将是第一个 证明促进细胞凋亡可以起到抗衰老的作用。我们建议通过以下方式来检验我们的假设 以下是具体目标。 1.测定线粒体和胞浆Gpx4缺陷小鼠对Gpx4诱导的敏感性。 氧化应激引起的细胞凋亡。表达线粒体形式Gpx4(MtGpx4)的转基因小鼠 或者，胞质形式的Gpx4(CytGpx4)将与Gpx4/-小鼠杂交，产生缺乏这两种基因的小鼠 MtGpx4或cytGpx4。MtGpx4或cytGpx4缺陷小鼠的细胞和组织将暴露于 各种类型的氧化应激和诱导细胞凋亡，CL水平和氧化，以及释放 线粒体中的促凋亡因子将随着年龄的增长而变化，并与WT小鼠进行比较。 2.检测线粒体和胞浆Gpx4缺陷小鼠清除受损Gpx4的能力 细胞，具体地说，就是能够引发肿瘤的细胞。肿瘤的突变频率和肿瘤数目 MtGpx4或cytGpx4缺陷小鼠的组织将随着年龄的增长进行测量，并与WT进行比较 老鼠。 3.测量线粒体或线粒体缺陷小鼠的存活率和年龄敏感的生物标志物 胞浆Gpx4。

The major observation of Project 3 in the current Program Project is that mice heterozygous for glutathione peroxidase 4 (Gpx4) have a significant increase in life span compared to wild type (WT) mice. This increase in life span occurs despite Gpx4+/- mice showing reduced expression of Gpx4 in all tissues throughout their life span; embryonic fibroblasts and liver from Gpx4+/- mice showing increased sensitivity to oxidative stress; and the levels of oxidative damage not being significantly altered in tissues of Gpx4+/- mice. We believe that the Gpx4+/- mouse model is a valuable new model for studying the mechanism of aging because the increase in life span of these mice appears to occur through a novel pathway. For example, there is no evidence that the increased life span of these mice arises either from increased resistance to oxidative stress/reduced oxidative damage or from alterations in insulin/IGF-l signaling, two pathways associated with increased longevity in invertebrates and rodents. We hypothesize that reduced Gpx4 expression increases longevity through a mechanism that involves alterations in the mitochondrialpathway ofapoptosis, leading to an increased sensitivity of cells to the induction ofapoptosis and an enhanced removal of damaged cells from the organism. If we confirm our hypothesis in this project, it will be the first demonstration that enhanced apoptosis can have an anti-aging action. We propose to test our hypothesis by the following Specific Aims. 1. To measure the sensitivity of mice deficient in either mitochondrial or cytosolic Gpx4 to the induction of apoptosis by oxidative stress. Transgenic mice expressing either the mitochondrial form of Gpx4 (mtGpx4) or the cytosolic form of Gpx4 (cytGpx4) will be crossed to Gpx4+/- mice to generate mice deficient in either mtGpx4 or cytGpx4. Cells and tissues of mice deficient in either mtGpx4 or cytGpx4 will be exposed to various types of oxidative stress and the induction of apoptosis, CL levels and oxidation, and the release of pro-apoptotic factors from mitochondria will be followed with age and compared to WT mice. 2. To measure the ability of mice deficient in either mitochondrial or cytosolic Gpx4 to remove damaged cells, specifically, cells that can give rise to tumors. The mutant frequency and the number of tumors in tissues from mice deficient in either mtGpx4 or cytGpx4 will be measured with age and compared to WT mice. 3. To measure the survival and age-sensitive biomarkers of mice deficient in either mitochondrial or cytosolic Gpx4.