Gene Expression, Caloric Restriction & the Aging Brain

描述(申请人提供)：为了加深对衰老的分子基础和卡路里限制(CR)延缓衰老的了解，我们使用代表6347个基因的高密度寡核苷酸阵列来研究骨骼肌(科学285：1390,1999)和两个脑区(自然遗传学25：294,2000)的衰老过程。C57BL/6小鼠大脑(新皮质和小脑)的衰老导致两个脑区的炎症反应、氧化应激(OS)和神经营养支持减少的差异基因表达模式。CR可以延缓哺乳动物的衰老，选择性地减弱与年龄相关的编码炎症和应激反应的基因的诱导。因此，需要检验的中心假设是，OS是大脑老化的主要原因，并支持观察到的与衰老相关的基因表达变化。我们提出了三个具体目标：具体目标1。老化大脑的基因表达谱：对照组和CR小鼠基因表达的时间模式。我们之前已经描述了5个月(年轻成年)和30个月(老年)B6小鼠的基因表达谱。我们建议扩展这些研究，以确定成年雄性B6小鼠大脑皮层、海马体和小脑的基因表达模式。每隔5个月对小鼠进行一次研究，从5个月龄开始，到35(对照组)到45个月(CR)龄结束。这项研究的主要重点是确定多个大脑区域与年龄相关的共同变化模式。具体目标2：确定与所选年龄相关基因表达变化的子集相关的细胞类型。利用原位杂交和免疫组织化学相结合的方法，将特定的mRNAs定位于单个细胞类型(即神经元、星形胶质细胞、小胶质细胞和血管内皮细胞)。具体目的3.对哺乳动物脑老化过程中活性氧物种(ROS)的作用进行遗传学测试。利用新开发的转基因小鼠，我们建议确定是否可以在一个过度表达MnSOD的菌株或另一个过度表达线粒体靶向过氧化氢酶和MnSOD的菌株中阻止随衰老观察到的基因表达的变化，这些基因表达代表衰老过程的组织特异性生物标记物。

DESCRIPTION (provided by applicant): In order to increase understanding of the molecular basis of aging and its retardation by caloric restriction (CR), we employed high density oligonucleotide arrays representing 6347 genes to study the aging process of skeletal muscle Science 285:1390, 1999) and two brain regions (Nature Genetics 25:294, 2000). Aging in the brain (neocortex and cerebellum) of C57BL/6 mice resulted in a differential gene expression pattern indicative of an inflammatory response, oxidative stress (OS) and reduced neurotrophic support in both brain regions. CR, which retards aging in mammals, selectively attenuated the age-associated induction of genes encoding inflammatory and stress responses. Thus, the central hypothesis to be tested is that OS is a major causative factor in brain aging, and underlies the observed changes in gene expression associate with aging. We propose three Specific Aims:Specific Aim1. Gene expression profiling of the aging brain: temporal patterns of gene expression in control and CR mice. We have previously described the gene expression profile of 5-month (young adult) and 30-month (aged) B6 mice. We propose to extend these studies to determine the patterns of gene expression in the neocortex, hippocampus and cerebellum of male B6 mice over the adult lifespan. Mice will be studied at five-month age intervals starting at 5 months of age and ending at 35 (control mice) to 45 (CR mice) months of age. The main emphasis of this study is to identify common patterns of age-associated changes in multiple brain regions. Specific Aim 2: Identification of cell types associated with a subset of selected age-associated changes in gene expression. In situ hybridizations combined with immunohistochemistry will be used to localize specific mRNAs to individual cell types (i.e., neurons, astrocytes, microglia and vascular endothelium).Specific Aim 3. A genetic test of the role of reactive oxygen species (ROS) in brain aging in mammals. Using newly developed transgenic mice, we propose to determine whether the alterations in gene expression observed with aging, which represent tissue-specific biomarkers of the aging process, can be prevented in either one strain overexpressing MnSOD or another strain overexpressing mitochondrially-targeted catalase and MnSOD.