Oxidative Stress and ERK Signaling in AC-5 KO Longevity

描述（由申请人提供）：5型腺苷酸环化酶（AC-5）异构体在几个器官中表达，但在心脏中是主要的异构体。为了研究AC-5的调控作用，我们建立了一个基因工程小鼠模型，其中AC-5的表达被敲除（AC-5 KO）。我们的初步研究表明，在AC-5 KO小鼠心脏慢性压力过载或慢性儿茶酚胺应激反应中具有保护作用。最近，我们观察到我们的AC-5 KO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症的不良影响。我们的发现支持了AC-5在调节衰老过程中起主要作用的概念。然而，增加AC-5小鼠寿命的机制是完全未知的。我们的初步研究表明AC-5 KO小鼠对细胞凋亡和氧化应激具有抗性。通过蛋白质组学方法，我们发现cAMP和AC介导的控制细胞生长和存活的Raf/MEK/ERK信号通路在AC-5 KO小鼠中被激活。Raf/MEK/ERK是响应氧化应激和细胞凋亡的主要信号通路之一。因此，本文的主要假设为：(A)敲除AC-5通过激活ERK及其下游靶点超氧化物歧化酶（SOD）增强细胞对氧化应激的抵抗力，从而延长细胞寿命。(B)敲除AC-5可以防止能量代谢产生的活性氧（ROS）的氧化和DMA损伤，这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进一步通过激活ERK激活抗凋亡和细胞存活机制，导致AC-5 KO小鼠抗衰老、抗压力过载和抗心肌缺血。这些研究将有助于阐明AC-5 KO小鼠长寿的分子机制，并进一步揭示抗衰老的细胞和分子机制。这项建议对公共卫生有重大影响。与老龄化相关的残疾对这个国家的公共卫生和经济产生了重大影响。找到分子开关，比如这个项目中描述的，可以改善衰老带来的残疾，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.