Role of sestrin family genes in antioxidant defense

说明(申请人提供)：活性氧物种(ROS)不仅是有害的代谢副产物，需要消除以防止损伤，而且是许多信号通路中的重要信使。作为一种信号，ROS通过过度氧化过氧化还蛋白(Prxs)来规避抗氧化防御，过氧化还蛋白是代谢过氧化产物的酶。然而，在信号传递之后，需要恢复抗氧化剂防火墙以防止氧化应激。最近我们发现，Sestrins是一个受P53抑癌基因(Hi95和PA26基因)调节表达的蛋白质家族，它是含有半胱氨酸亚磺酸的过氧化Prxs的再生所必需的，从而重建抗氧化防御。抑制Sestrins会导致严重的氧化应激，导致细胞凋亡或过早衰老。我们推测，Sestrins是抗氧化防御和ROS相关信号的关键调节器，可能决定细胞类型对促氧化剂治疗的特定反应，以及信号转导的结果，从而代表了ROS相关病理治疗的有吸引力的靶点。在该计划中，我们将通过研究参与过氧化物催化的蛋白质伙伴、不同水平的Sestrin基因调控机制、依赖于胁迫和各种生理信号的Sestrin活性和细胞内定位的变化来确定Sestrin蛋白抗氧化活性的分子机制。我们将研究Sestrin家族基因在调节正常生理信号中的作用，以及在应激过程中决定细胞命运的作用。我们将通过分析信号转导的效率来研究Sestrin基因在细胞因子信号转导中的作用，这些信号转导依赖于Hi95、PA26和SesnS的表达水平、细胞内定位和不同亚型的比例。通过分析Sestrin基因响应P53的调控模式，我们将阐明它们在保护基因组免受氧化损伤中的作用，以及它们在P53介导的遗传稳定性控制中的作用。将在转基因和基因敲除小鼠模型中探索Sestrins在发育和组织反应中的作用。Sestrins在癌症发生中的潜在作用将在肺癌模型中进行评估。这一结果将为Sestrins作为治疗干预目标的潜在价值提供估计。

DESCRIPTION (provided by applicant): Reactive oxygen species (ROS) are not only harmful by-products of metabolism that need be eliminated to prevent injury, but also important messengers serving in numerous signaling pathways. Acting as a signal, ROS circumvents antioxidant defense by overoxidizing peroxiredoxins (Prxs), the enzymes metabolizing peroxides. However, after the signal is conveyed the antioxidant firewall needs to be restored to prevent oxidative stress. Recently we found that sestrins, a family of proteins whose expression is modulated by p53 tumor suppressor (Hi95 and PA26 genes), are required for regeneration of the over-oxidized Prxs containing cysteine sulfinic acid, thus reestablishing the antioxidant defense. Inhibition of sestrins leads to severe oxidative stress, resulting in apoptosis or premature senescence. We hypothesize that sestrins being critical modulators of both antioxidant defense and ROS-related signaling might determine cell type specific responses to pro-oxidant treatments, and the outcome of signaling, thus representing attractive targets for therapy of ROS-related pathologies. In the proposed program, we are going to determine molecular mechanisms of antioxidant activity of sestrin proteins by studying the protein partners involved in the catalysis of peroxides, the mechanisms of sestrin gene regulation at different levels, the changes in the activity and intracellular localization of sestrins depending on stresses and various physiological signals. We are going to study the roles of sestrin family genes in the modulation of normal physiological signaling, as well as in determining cell fate during stress. We shall study the role of sestrin genes in the cytokine signaling by analyzing the efficiency of signal transduction depending on the levels of expression, intracellular localization, and the proportions of different isoforms of Hi95, PA26 and SesnS. By analyzing the modes of regulation of sestrin genes in response to p53, we will elucidate their role in the protection of the genome against oxidative damage, and their contribution to the p53-mediated control of genetic stability. Roles of sestrins in development and organismic responses will be explored in transgenic and knockdown mouse models. The potential involvement of sestrins in cancerogenesis will be evaluated in a lung cancer model. The results will provide an estimate of the potential value of sestrins as targets for therapeutic interventions.