The Sir2-p53-IGF Link in Mammalian Life-Span Control

描述（由申请人提供）：本申请是为了响应通知号NOT-OD-09-058而提交的，NIH宣布恢复法案资金可用于竞争性修订申请。本竞争性修订申请涉及母公司资助1 RO 1 AG 026094，哺乳动物寿命控制中的Sir 2-p53-IGF链接。 我们已经确定了胰岛素/IGF信号通路作为哺乳动物长寿的关键介质，受肿瘤抑制因子p53的控制。正常p53活性的破坏导致IGF-1受体（IGF-1 R）的表达增加，并与小鼠寿命缩短和加速衰老有关。这种IGF-1 R活性的增加显然是突变型p53活性小鼠寿命缩短和加速衰老的直接原因，因为Igf-1 R基因的单倍不足完全挽救了寿命。根据这项竞争性修订申请提出的实验旨在了解IGF-1 R表达增加的分子机制，这可能会显着损害寿命。这些实验并不包括在母赠款的具体目标之内，因此代表着范围的显著扩大。 在第一个补充特异性目标（SSA）中，我们将检验IGF-1受体受miR-675（一种由H19基因（SSA 1）编码的microRNA）调控的假设。对IGF-1 R mRNA的3 'UTR中的潜在microRNA结合位点的计算分析鉴定了作为miR-675的靶标的高度保守位点。IGF-1 R mRNA中的该位点由人类和非人类灵长类动物、啮齿类动物和其他脊椎动物共享，包括鸡。miR-675由H19基因编码，H19基因是p53的转录靶标。因此，miR-675对IGF-1 R水平的影响可以提供p53活性和寿命之间的干扰之间的直接联系。在第二个SSA中，我们将测试以下假设：小鼠中H19和miR-675表达的缺陷通过增加IGF-1 R水平而降低寿命（SSA 2）。我们将p44 Tg小鼠与H19 BAC小鼠杂交，H19 BAC小鼠是由Karl Pfeifer博士（NIH）开发的过表达H19基因的转基因小鼠品系。如果p44 Tg小鼠中H19表达的缺陷是其寿命缩短的原因，那么将p44 Tg; H19 BAC小鼠中的H19水平恢复到正常水平应该可以挽救寿命。此外，如果我们提出的通过miR-675调节IGF-1 R翻译的分子机制是正确的，那么在p44 Tg; H19 BAC小鼠中，IGF-1 R蛋白的正常水平的恢复将伴随着寿命的挽救。 通过扩大母基金的范围，以包括实验来测试这些假设，我们预计，所要求的修订将使我们有机会探索新的机制，通过这些机制建立调节寿命的中枢通路。 公共卫生相关性：本申请是为了响应通知号NOT-OD-09-058而提交的，NIH宣布为竞争性修订申请提供恢复法案资金。本竞争性修订申请涉及母公司资助1 RO 1 AG 026094，哺乳动物寿命控制中的Sir 2-p53-IGF链接。 我们已经确定了胰岛素/IGF信号通路作为哺乳动物长寿的关键介质，受肿瘤抑制因子p53的控制。正常p53活性的破坏导致IGF-1受体（IGF-1 R）的表达增加，并与小鼠寿命缩短和加速衰老有关。根据这项竞争性修订申请提出的实验旨在了解IGF-1 R表达增加的分子机制，这可能会显着损害寿命。这些实验并不包括在母赠款的具体目标之内，因此代表着范围的显著扩大。

DESCRIPTION (provided by applicant): This application is being submitted in response to Notice Number NOT-OD-09-058, NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications. This competitive revision application pertains to parent grant 1RO1 AG026094, The Sir2-p53-IGF link in mammalian life span control. We have identified the insulin/IGF signaling pathway as a key mediator of mammalian longevity that is subject to control by the tumor suppressor p53. Disruption of normal p53 activity results in increased expression of the IGF-1 receptor (IGF-1R) and is linked to decreased longevity and accelerated aging in mice. This increase in IGF-1R activity is apparently a direct cause of reduced longevity and accelerated aging in mice with mutant p53 activity as haploinsufficiency for the Igf-1r gene rescues life span completely. Experiments proposed under this competitive revision application aim to understand the molecular mechanism underlying increases in IGF-1R expression that can significantly impair longevity. These experiments are not covered by the specific aims of the parent grant and thus represent a significant expansion of scope. In the first supplemental specific aim (SSA), we will test the hypothesis that the IGF-1 receptor is regulated by miR-675, a microRNA encoded by the H19 gene (SSA1). Computation analysis of potential microRNA binding sites in the 3'UTR of the IGF-1R mRNA identified a highly conserved site as a target of miR-675. This site in the IGF-1R mRNA is shared by humans and non-human primates, rodents, and other vertebrates down to and including chickens. miR-675 is encoded by the H19 gene, a transcriptional target of p53. Thus, the effect of miR-675 on the level of the IGF-1R could provide a direct link between disturbances in p53 activity and life span. In the second SSA, we will test the hypothesis that deficiencies in H19 and miR-675 expression in mice reduce longevity by increasing the level of the IGF-1R (SSA 2). We will cross p44Tg mice with H19BAC mice, a strain of transgenic mice developed by Dr. Karl Pfeifer (NIH) that over-express the H19 gene. If the deficit in H19 expression in p44Tg mice is the cause of their shortened life span, restoring H19 levels to normal in p44Tg;H19BAC mice should rescue longevity. Furthermore, if the molecular mechanism we have proposed for regulation of IGF-1R translation by miR-675 is correct, then rescue of life span will be accompanied by restoration of normal levels of IGF-1R protein in p44Tg;H19BAC mice. By expanding the scope of the parent grant to include experiments to test these hypotheses, we anticipate that the requested revision will give us the opportunity to explore novel mechanisms by which central pathways regulating life span are established. PUBLIC HEALTH RELEVANCE: This application is being submitted in response to Notice Number NOT-OD-09-058, NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications. This competitive revision application pertains to parent grant 1RO1 AG026094, The Sir2-p53-IGF link in mammalian life span control. We have identified the insulin/IGF signaling pathway as a key mediator of mammalian longevity that is subject to control by the tumor suppressor p53. Disruption of normal p53 activity results in increased expression of the IGF-1 receptor (IGF-1R) and is linked to decreased longevity and accelerated aging in mice. Experiments proposed under this competitive revision application aim to understand the molecular mechanism underlying increases in IGF-1R expression that can significantly impair longevity. These experiments are not covered by the specific aims of the parent grant and thus represent a significant expansion of scope.