DOES REDUCED GLUTATHIONE PEROXIDASE 4 INCREASE LIFE SPAN BY ALTERING APOPTOSIS

项目3在本项目中的主要观察结果是谷胱甘肽杂合子小鼠 与野生型（WT）小鼠相比，过氧化物酶4（Gpx 4）小鼠的寿命显著增加。这种增加 尽管Gpx 4 +/-小鼠在其整个生命周期中的所有组织中显示Gpx 4表达减少， 来自Gpx 4 +/-小鼠的胚胎成纤维细胞和肝脏显示出对氧化应激的敏感性增加; 并且在Gpx 4 +/-小鼠的组织中氧化损伤的水平没有显著改变。 我们认为Gpx 4 +/-小鼠模型是研究衰老机制的一个有价值的新模型 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。比如说， 没有证据表明这些小鼠寿命的延长是由于对 氧化应激/减少的氧化损伤或来自胰岛素/IGF-1信号传导的改变，两种途径 与无脊椎动物和啮齿动物寿命的延长有关。我们假设减少Gpx 4 表达通过一种机制增加寿命， 导致细胞对三元共聚物诱导的敏感性增加， 从生物体中清除受损细胞。如果我们在这个项目中证实了我们的假设，这将是第一个 这证明了增强的细胞凋亡可以具有抗衰老作用。我们建议通过以下方式来检验我们的假设： 以下具体目标。 1.为了测量线粒体或胞质Gpx 4缺陷的小鼠对Gpx 4诱导的敏感性， 氧化应激引起的细胞凋亡。表达线粒体形式Gpx 4（mtGpx 4）的转基因小鼠 或者将Gpx 4的胞质形式（cytGpx 4）与Gpx 4 +/-小鼠杂交以产生在以下任一方面缺陷的小鼠： mtGpx 4或cytGpx 4。将mtGpx 4或cytGpx 4缺陷小鼠的细胞和组织暴露于 各种类型的氧化应激和诱导凋亡，CL水平和氧化，以及释放 来自线粒体的促凋亡因子将随年龄而变化，并与WT小鼠进行比较。 2.为了测量线粒体或胞质Gpx 4缺陷的小鼠去除受损的细胞的能力， 细胞，特别是能导致肿瘤的细胞。突变频率和肿瘤数量 来自mtGpx 4或cytGpx 4缺陷小鼠的组织将随年龄测量并与WT比较 小鼠 3.为了测量线粒体或线粒体基因缺陷小鼠的存活率和年龄敏感性生物标志物， 胞浆Gpx 4。

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.