Singlet Oxygen Signaling

描述（由申请人提供）：从细菌到植物和动物的需氧生物已经进化出传感、信号传导和保护机制，以科普细胞内和细胞外不可避免地产生的各种活性氧（ROS）。阐明这些机制是一个具有广泛生物学意义的问题。虽然细胞对活性氧（如过氧化氢和超氧化物）的反应已被广泛研究，但对单线态氧的生物反应知之甚少，单线态氧是一种特别有毒的活性氧，会对许多关键细胞成分（如不饱和脂质、蛋白质和DNA）造成氧化损伤。单线态氧通常由光敏反应产生，光敏反应是在患有卟啉症和可能的年龄相关性黄斑变性的人中观察到的光氧化组织损伤的基础。另一方面，光敏化已被用于某些人类癌症的光动力疗法的策略中。本研究的目的是利用分子遗传学和基因组学的方法来研究单细胞绿色植物莱茵衣藻（Chlamydiumreinhardtii）的单线态氧驯化反应，以解决单线态氧信号转导知识相对不足的问题。像其他产氧光养生物一样，衣原体必须科普高浓度的内源性氧和叶绿素，一种有效的光敏剂，因此可能已经进化出特别强大的机制来感知和响应单线态氧。本发明的具体目的是（1）对衣原体的单线态氧适应反应进行生理和生化表征，（2）使用全基因组微阵列分析来鉴定在单线态氧适应期间表达变化的基因组，（3）使用反向遗传学方法来测试单线态氧适应中特定候选基因的必要性，和（4）进行单线态氧驯化的正向遗传解剖，包括（5）分离在已经鉴定的驯化突变体中有缺陷的基因，称为SOS 1。这项研究将有助于阐明其他生物体中单线态氧生物学的研究，并提供有关真核细胞如何感知和响应单线态氧的基础知识。

DESCRIPTION (provided by applicant): Aerobic organisms, from bacteria to plants and animals, have evolved sensing, signaling, and protective mechanisms to cope with various reactive oxygen species (ROS) that are inevitably generated both intra- and extracellularly. Elucidation of these mechanisms is a problem of broad biological significance. Although cellular responses to ROS such as hydrogen peroxide and superoxide have been extensively studied, relatively little is known about biological responses to singlet oxygen, an especially toxic type of ROS that causes oxidative damage to numerous critical cellular components, such as unsaturated lipids, proteins, and DNA. Singlet oxygen is commonly generated by photosensitization reactions that are the basis for the photooxidative tissue damage observed in humans suffering from porphyria and possibly age-related macular degeneration. On the other hand, photosensitization has been exploited in strategies for photodynamic therapy of certain human cancers. This proposal aims to address the relative deficiency of knowledge about singlet oxygen signaling by using molecular genetic and genomic approaches to dissect the singlet oxygen acclimation response in a unicelluar green alga, Chlamydomonas reinhardtii, a model photosynthetic eukaryote. Like other oxygenic phototrophs, Chlamydomonas must cope with high endogenous concentrations of both oxygen and chlorophyll, a potent photosensitizer and may therefore have evolved particularly robust mechanisms for perceiving and responding to singlet oxygen. The specific aims of this proposal are (1) to perform physiological and biochemical characterization of the singlet oxygen acclimation response in Chlamydomonas, (2) to use whole-genome microarray analysis to identify the set of genes whose expression changes during acclimation to singlet oxygen, (3) to use reverse genetics approaches to test the necessity of specific candidate genes in singlet oxygen acclimation, and (4) to perform a forward genetic dissection of singlet oxygen acclimation, including (5) the isolation of a gene that is defective in an already identified acclimation mutant, called sos1. This investigation will help illuminate studies of singlet oxygen biology in other organisms and provide fundamental knowledge about how eukaryotic cells sense and respond to singlet oxygen.