Oxidative Stress and ERK Signaling in AC-5 KO Longevity

描述(申请人提供)：5型腺酰环化酶(AC-5)亚型在几个器官中表达，但在心脏中是主要的亚型。为了研究AC-5调控的作用，我们建立了一个基因工程小鼠模型，在该模型中AC-5的表达被敲除(AC-5 KO)。我们的初步研究表明，在AC-5KO小鼠中，对慢性压力超负荷或慢性儿茶酚胺应激的心脏反应具有保护作用。最近，我们观察到我们的AC-5KO小鼠比WT小鼠寿命更长，并且没有表现出衰老对心脏和骨质疏松的不利影响。我们的发现支持AC-5在调节衰老过程中发挥主要作用的概念。然而，AC-5小鼠寿命延长的机制完全不清楚。我们的初步研究表明，AC-5KO小鼠对细胞凋亡和氧化应激具有抵抗力。利用蛋白质组学方法，我们发现在AC-5KO小鼠中，由cAMP和AC介导的控制细胞生长和存活的Raf/MEK/ERK信号通路被激活。RAF/MEK/ERK是氧化应激和细胞凋亡所激活的主要信号通路之一。因此，这一提议的主要假设是：(A)敲除AC-5通过激活ERK及其下游靶标超氧化物歧化酶(SOD)来增强细胞对氧化应激的抵抗力，从而延长寿命。(B)敲除AC-5可以防止能量代谢产生的活性氧物种(ROS)造成的氧化和DMA损伤，而ROS是衰老过程的关键机制。AC-5的缺失减少了线粒体ROS的产生和DNA的氧化损伤。(C)敲除AC-5可通过激活ERK进一步激活抗凋亡和细胞存活机制(S)，从而使AC-5 KO小鼠对抗衰老、压力超负荷和心肌缺血。这些研究将有助于阐明AC-5KO小鼠长寿的分子机制，并进一步为抗衰老的细胞和分子机制提供见解。这项建议对公众健康有重大影响。与老龄化相关的残疾对这个国家的公共健康和经济有重大影响。寻找分子开关，如本项目中描述的那样，可以改善随着年龄增长而导致的残疾，这将是向前迈出的重要一步。

DESCRIPTION (provided by applicant): The Type 5 adenylyl cyclase (AC-5) isoform is expressed in several organs, but is a predominant isoform in the heart. To study the role of AC-5 regulation, we generated a genetically engineered mouse model in which the expression of AC-5 is knocked out (AC-5 KO). Our initial studies demonstrated a protective role in response to either chronic pressure-overload or chronic catecholamine stress in the heart in the AC-5 KO mice. Recently, we observed that our AC-5 KO mice live longer than WT mice and do not exhibit the adverse effects of aging on the heart and on osteoporosis. Our finding supports the concept that AC-5 plays a major role in the regulation of the aging process. However, the mechanism for increased longevity in AC-5 mice is completely unknown. Our preliminary studies have demonstrated that AC-5 KO mice are resistant to apoptosis and oxidative stress. By using proteomic approaches we found that the Raf/MEK/ERK signaling pathway, which controls cell growth and survival, mediated by cAMP and AC, is activated in AC-5 KO mice. Raf/MEK/ERK is one of major signaling pathways activated in response to oxidative stress and apoptosis. Therefore, the main hypotheses of this proposal are: (A) Knocking out AC-5 enhances cellular resistance to oxidative stress through the activation of ERK and its downstream target superoxide dismutase (SOD), which results in extended life span. (B) Knocking out AC-5 protects against oxidative and DMA damage from reactive oxygen species (ROS) produced by energy metabolism, a key mechanism of aging process. The deletion of AC-5 decreases the mitochondrial ROS production and oxidative DNA damage. (C) Knocking out AC-5 further evokes anti-apoptotic and cell survival mechanism(s) through the activation of ERK, which lead to AC-5 KO mice against aging, pressure overload and myocardial ischemia. These studies will lead to an elucidation of molecular mechanisms of longevity in AC-5 KO mice and further provide insights into cellular and molecular mechanisms of anti-aging. This proposal has major implications for public health. The disability associated with aging has a major impact on the public health and the economy of this country. Finding molecular switches, such as the one described in this project, could ameliorate disability with aging and would be a major step forward.