Role of Proline in Redox Homeostasis and Apoptosis

描述（由申请人提供）：本研究的总体目标是提供脯氨酸和脯氨酸代谢如何影响氧化还原相关生理过程的更完整的分子理解。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、癌症和精神分裂症具有重要影响。脯氨酸脱氢酶（PRODH）通过在p53介导的细胞凋亡过程中产生脯氨酸依赖的活性氧（ROS）在肿瘤抑制中起重要作用。脯氨酸的一个不太被认可的作用是其保护免受氧化应激的潜力，这是一种直到最近才在哺乳动物系统中相对未被探索的特性。我们的中心假设是，脯氨酸功能作为广泛的抗氧化剂在哺乳动物细胞在应激过程中清除活性氧和维持氧化还原稳态。这一假设得到了我们强有力的初步结果的支持，这些结果显示哺乳动物细胞中的细胞内脯氨酸积累与ROS水平降低和对氧化应激的保护增加相关。我们的初步研究结果还表明，脯氨酸的生物合成上调氧化胁迫条件下，提供证据表明，脯氨酸积累是一种生理应激反应。虽然有强有力的证据表明脯氨酸在细胞凋亡途径中具有重要作用，但脯氨酸抑制ROS和影响氧化还原稳态的能力尚未确定。本项目的主要目的是评估脯氨酸对各种细胞类型和体内氧化致癌作用中ROS介导的应激的保护功能。我们还旨在阐明脯氨酸作为ROS清除剂的作用机制，并发现生理胁迫条件下脯氨酸代谢的调节因子。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能力。2.阐明脯氨酸清除活性氧的机制。3.建立脯氨酸保护氧化应激的生理意义。4.鉴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缺陷表现为神经功能障碍，如精神分裂症和癫痫发作的发病率增加。脯氨酸代谢中的一种关键酶脯氨酸脱氢酶被肿瘤抑制因子p53上调，产生导致细胞死亡的活性氧，从而有助于预防癌症。本计画将探讨脯氨酸及脯氨酸代谢如何调节细胞活性氧及对抗氧化压力。这项研究的结果将为脯氨酸代谢如何促进癌症和精神疾病提供分子理解，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缺陷表现为神经功能障碍，如精神分裂症和癫痫发作的发病率增加。脯氨酸代谢中的关键酶脯氨酸脱氢酶被肿瘤抑制因子p53上调，产生导致细胞死亡的活性氧，从而有助于预防癌症。本计画将探讨脯氨酸及脯氨酸代谢如何调节细胞活性氧及对抗氧化压力。这项研究的结果将为脯氨酸代谢如何促进癌症和精神疾病提供分子理解，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.