LIFESPAN AND MECHANISMS OF STRESS RESISTANCE IN GH/IGF MUTANTS

项目3的重点是这样一种观点，即在生命早期，GH和/或IGF-1信号的暴露减少， 寿命延长和一系列的细胞异常，我们已经记录了成纤维细胞， 长寿的Snell侏儒突变小鼠，包括对ER应激诱导剂的敏感性，对广泛的 的致死剂，并抵抗抑制质膜氧化还原系统（PMRS）。八个品种 本项目将比较的小鼠包括：（a）Snell侏儒小鼠;（B）缺乏IGF-1的LID小鼠 （c）IGF-1 midi小鼠，具有异常低水平的IGF-1和高GH水平;（d）IGF-1 R het小鼠，对IGF-1具有异常低应答，（e）GHRKO小鼠，其在所有组织中缺乏GH受体; 和（f）三种新的组织特异性GHR突变体，其分别在肝脏中缺乏GH受体， 脂肪组织或骨骼肌。目的1将测试来自这些小鼠的皮肤来源的成纤维细胞系， 评估对致死性氧化和非氧化胁迫（过氧化物、百草枯、镉和紫外线）的抗性， Snell侏儒细胞对其具有抗性，以及未折叠蛋白质应答的诱导剂（衣霉素， Thapsigargin），Snell细胞对其敏感。PMRS反应性将使用非致死剂量的 鱼藤酮来自一周大的小鼠的成纤维细胞将被测试，以观察压力模式是否需要出生后 成熟，并从中年小鼠，看看是否抗应激能力持续到中年。预处理 将对脂肪细胞进行测试，以观察当从长寿供体储备中取出时，它们是否也显示出抗应激性。 目标2，使用生物化学方法，将测试体外成纤维细胞，以及来自完整和紫外线暴露的组织。 小鼠，用于参与应激抗性的四种途径：ERK家族MAP激酶信号，mTOR的活化， 未折叠蛋白反应的修复和凋亡途径，以及热休克蛋白的mRNA水平 和HSF。目标3将测量三种组织特异性GHRKO模型的寿命， 对年龄敏感的特征（免疫状态、白内障和活动）作为延迟衰老的指标。项目3将 为项目的其他部分提供资源：从终末尸检到核心B的组织，成纤维细胞 用于基因表达分析的裂解物归项目1，脂肪组织库归项目4。项目3将 提供了假设的测试，即调节应激抗性的内分泌操纵导致 延长寿命，并与整个计划合作，将揭示新的联系 将细胞应激抗性与内分泌和脂肪组织的遗传和药理学调节剂联系起来。 相关性（参见说明）： 该项目旨在为衰老和晚年疾病的生物学提供线索， 调查衰老过程，并确认或反驳有关抗衰老药物的想法。积极 研究结果可能为预防医学提供新的策略。

PROJECT 3 focuses on the idea that diminished exposure to GH and/or IGF-1 signals in early life leads both to lifespan extension and to a spectrum of cellular abnormalities that we have documented in fibroblasts from long-lived Snell dwarf mutant mice, including sensitivity to inducers of ER stress, resistance to a broad range of lethal agents, and resistance to inhibition of the plasma membrane redox system (PMRS). Eight varieties of mice will be compared in the project, including: (a) Snell dwarf mice; (b) LID mice that lack IGF-1 expression in liver; (c) IGF-1 midi mice, with abnormally low levels of IGF-1 and high GH levels; (d) IGF-1 R het mice, with abnormally low response to IGF-1, (e) GHRKO mice, which lack GH receptors in all tissues; and (f) three new varieties of tissue-specific GHR mutants, which lack GH receptors, respectively, in liver, adipose tissue, or skeletal muscle. Aim 1will test skin-derived fibroblast cell lines from these mice, evaluating resistance to lethal oxidative and non-oxidative stresses (peroxide, paraquat, cadmium, and UV), to which Snell dwarf cells are resistant, and inducers of the unfolded protein response (tunicamycin, thapsigargin), to which Snell cells are sensitive. PMRS reactivity will be tested using non-lethal doses of rotenone. Fibroblasts from week-old mice will be tested to see if stress patterns require post-natal maturation, and from middle-aged mice to see if the stress-resistance profile lasts into midlife. Pre- adipocytes will be tested to see if they, too, show stress resistance when taken from long-lived donor stocks. Aim 2, using biochemical approaches, will test in vitro fibrobtasts, and tissues from intact and UV-exposed mice, for four pathways involved in stress resistance: Erk-family MAP kinase signals, activation of mTOR, repair and apoptotic pathways of the unfolded protein response, and mRNA levels for heat shock proteins and HSFs. Aim 3 will measure lifespan in the three tissue-specific GHRKO models, and will measure three age-sensitive traits (immune status, cataracts, and activity) as indices of delayed aging. Project 3 will provide resources to other parts of the program: tissues from terminal necropsies to Core B, fibroblast lysates for gene expression analyses to Project 1, and adipose tissue depots to Project 4. Project 3 will provide tests of the hypothesis that endocrine manipulations that modulate stress resistance lead to extended longevity, and in collaboration with the program as a whole will shed new light on the connections linking cellular stress resistance to genetic and pharmacologic modulators of endocrine and adipose tissues. RELEVANCE (See instructions): This project is intended to suggest clues about the biology of aging and late-life illness, provide models for investigation of the aging process, and confirm or refute ideas about proposed anti-aging drugs. Positive findings could, potentially, suggest new strategies in preventive medicine.