Gene Expression, Caloric Restriction & the Aging Brain

描述（由申请人提供）：为了增加对衰老的分子基础及其通过热量限制（CR）的延缓的理解，我们采用代表6347个基因的高密度寡核苷酸阵列来研究骨骼肌（Science 285：1390，1999）和两个脑区域（Nature Genetics 25：294，2000）的衰老过程。C57 BL/6小鼠大脑（新皮质和小脑）的衰老导致了差异基因表达模式，表明两个大脑区域的炎症反应、氧化应激（OS）和神经营养支持减少。延缓哺乳动物衰老的CR选择性地减弱了与年龄相关的炎症和应激反应基因的诱导。因此，待检验的中心假设是OS是脑老化的主要致病因素，并且是观察到的与老化相关的基因表达变化的基础。我们提出三个具体目标：具体目标1。衰老大脑的基因表达谱：对照和CR小鼠基因表达的时间模式。我们先前已经描述了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，以确定在成年期的雄性B6小鼠的新皮层，海马和小脑的基因表达模式。将以5个月龄间隔研究小鼠，从5个月龄开始，到35个月龄（对照小鼠）至45个月龄（CR小鼠）结束。这项研究的主要重点是确定多个大脑区域中与年龄相关的变化的共同模式。具体目标2：鉴定与选定的年龄相关基因表达变化子集相关的细胞类型。原位杂交结合免疫组织化学将用于将特异性mRNA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）。活性氧（ROS）在哺乳动物脑老化中作用的遗传测试。使用新开发的转基因小鼠，我们建议，以确定是否可以防止在一个菌株过表达MnSOD或另一个菌株过表达神经靶向过氧化氢酶和MnSOD的基因表达的变化与老化，这代表组织特异性生物标志物的老化过程中观察到的。

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.