Role of Proline in Redox Homeostasis and Apoptosis

描述(由申请人提供)：这项研究的总体目标是提供一个更完整的分子理解如何影响与氧化还原相关的生理过程的Pro和Pro代谢。脯氨酸代谢被认为对生物能量学、细胞氧化还原控制、细胞凋亡、癌症和精神分裂症有重要影响。在P53介导的细胞凋亡过程中，线粒体中的Pro脱氢酶(PROH)通过产生依赖于Pro的活性氧物种(ROS)在肿瘤抑制中发挥重要作用。一个不太为人所熟知的作用是它具有抵御氧化应激的潜力，这一特性直到最近才在哺乳动物系统中被相对探索。我们的中心假设是，在应激过程中，Pro通过清除ROS和维持氧化还原动态平衡，在哺乳动物细胞中发挥广泛的抗氧化剂作用。这一假设得到了我们强有力的初步结果的支持，这些结果表明，哺乳动物细胞内Pro的积累与ROS水平的降低和对氧化应激的增强保护相关。我们的初步结果还表明，在氧化胁迫条件下，Pro的生物合成被上调，这为Pro的积累是一种生理胁迫反应提供了证据。虽然有强有力的证据表明，Pro在细胞凋亡途径中具有重要的作用，但Pro清除ROS和影响氧化还原动态平衡的能力尚未建立。本项目的主要目的是评估在不同细胞类型和体内氧化致癌过程中，脯氨酸对ROS介导的应激反应的保护作用。我们还旨在阐明Pro作为ROS清除剂的作用机制，并发现在生理应激条件下Pro代谢的调节因子。本研究的具体目的是：1.测定内源性脯氨酸对氧化应激的保护作用。2.阐明了脯氨酸清除ROS的机制。3.确立了Pro对氧化应激的保护作用的生理意义。4.确定调节脯氨酸代谢和ROS诱导的细胞死亡的基因。脯氨酸代谢基因的先天错误表现为神经功能障碍，如精神分裂症和癫痫发生率的增加。Pro代谢中的一个关键酶，Pro脱氢酶，被肿瘤抑制基因P53上调，产生活性氧物种，导致细胞死亡，从而帮助预防癌症。这个项目将研究Pro和Pro代谢如何调节细胞内的活性氧物种，保护细胞免受氧化应激。这项研究的结果将为Pro代谢如何导致癌症和精神疾病提供分子上的理解，并可能为治疗干预提供机会。公共卫生相关性：脯氨酸代谢基因的先天错误表现为神经功能障碍，如精神分裂症和癫痫发生率的增加。Pro代谢中的一个关键酶，Pro脱氢酶，被肿瘤抑制基因P53上调，产生活性氧物种，导致细胞死亡，从而帮助预防癌症。这个项目将研究Pro和Pro代谢如何调节细胞内的活性氧物种，保护细胞免受氧化应激。这项研究的结果将为Pro代谢如何导致癌症和精神疾病提供分子上的理解，并可能为治疗干预提供机会。

DESCRIPTION (provided by applicant): The overall goal of this study is to provide a more complete molecular understanding of how proline and proline metabolism impact redox-linked physiological processes. Proline metabolism is recognized as having an important impact on bioenergetics, cellular redox control, apoptosis, cancer, and schizophrenia. The mitochondrion enzyme proline dehydrogenase (PRODH) plays an important role in tumor suppression by generating proline-dependent reactive oxygen species (ROS) during p53-mediated apoptosis. A less well-recognized role of proline is its potential to protect against oxidative stress, a property that has been relatively unexplored in mammalian systems until only recently. Our central hypothesis is that proline functions as broad-based antioxidant in mammalian cells during stress by scavenging ROS and maintaining redox homeostasis. This hypothesis is supported by our strong preliminary results which show intracellular proline accumulation in mammalian cells correlates with decreased ROS levels and increased protection against oxidative stress. Our preliminary results also show that proline biosynthesis is upregulated under oxidative stress conditions, providing evidence that proline accumulation is a physiological stress response. While there is strong evidence that proline has an important role in cellular apoptotic pathways, the ability of proline to scavenge ROS and impact redox homeostasis has not been established. The main objectives of this project are to evaluate the protective function of proline against ROS mediated stress in various cell types and in vivo oxidative carcinogenesis. We also aim to elucidate the mechanisms whereby proline functions as a ROS scavenger and discover regulatory factors of proline metabolism under physiological stress conditions. The specific aims of this study are: 1. Determine the protective ability of endogenous proline against oxidative stress. 2. Elucidate the mechanism by which proline scavenges ROS. 3. Establish physiological significance of proline protection against oxidative stress. 4. Identify genes that regulate proline metabolism and ROS-induced cell death. Inborn errors in proline metabolic genes are manifested in neurological dysfunctions such as schizophrenia and increased incidence of seizures. A key enzyme in proline metabolism, proline dehydrogenase, is up- regulated by tumor suppressor p53 to generate reactive oxygen species that lead to cell death, thus helping to prevent cancer. This project will investigate how proline and proline metabolism modulate cellular reactive oxygen species and protect against oxidative stress. The results from this study will provide a molecular understanding for how proline metabolism contributes to cancer and mental illness and potentially suggest opportunities for therapeutic intervention. PUBLIC HEALTH RELEVANCE: Inborn errors in proline metabolic genes are manifested in neurological dysfunctions such as schizophrenia and increased incidence of seizures. A key enzyme in proline metabolism, proline dehydrogenase, is upregulated by tumor suppressor p53 to generate reactive oxygen species that lead to cell death, thus helping to prevent cancer. This project will investigate how proline and proline metabolism modulate cellular reactive oxygen species and protect against oxidative stress. The results from this study will provide a molecular understanding for how proline metabolism contributes to cancer and mental illness and potentially suggest opportunities for therapeutic intervention.