Characterization of a novel ferroptosis regulator

铁凋亡是一种新发现的细胞死亡方式，不仅因其对病理条件（如缺血/再灌注损伤和神经退行性变）的贡献而引起了极大的兴趣，而且作为一种新兴的治疗难以治疗的肿瘤的策略。谷胱甘肽过氧化物酶4 （GPX4）通过抑制磷脂过氧化过程负调控铁下垂。因此，初步尝试在体内以GPX4为药理学靶点，作为触发癌细胞铁下垂的手段，尽管这些方法迄今为止只产生了中等结果。这很可能是由于我们对最终调节这种细胞死亡形式的过程的知识有限。在这篇文章中，我们首先介绍了一个无偏倚的cDNA过表达筛选的结果，旨在鉴定能够完全弥补GPX4缺失的基因。这种方法使我们能够鉴定出一种尚未被识别的氧化还原酶，它可以完全防止GPX4缺失或药物抑制引起的铁死亡。在这个项目中，我们的目标是表征这种酶如何能够在分子水平上绕过对GPX4的要求。我们将利用一系列最先进的方法，包括CRISPR/Cas技术，代谢组学，（oxi）脂质学和化学生物学，来阐明这种新型铁下沉调节剂的机制细节。此外，该途径的体内相关性也将通过两种新型小鼠模型的表征进行评估，这些模型基于该氧化还原酶的组成性缺失或有条件的组织特异性过表达。我们相信，这里产生的数据将从本质上更好地理解代谢负债使细胞对铁下垂敏感。此外，将发现新的机会来有效地靶向这种形式的细胞死亡，最终目标是确定新的策略来根除对标准治疗有抗性的癌细胞。

Ferroptosis is a newly identified cell death modality that has attracted overwhelming interest not only for its contribution to pathological conditions, such as ischemia/reperfusion injury and neurodegeneration, but also as an emerging strategy to eradicate hard to treat tumors. Ferroptosis is negatively regulated by glutathione peroxidase 4 (GPX4) by suppressing the process of phospholipid peroxidation. Therefore, initial attempts have been made to pharmacologically target GPX4 in vivo as a mean to trigger ferroptosis in cancer cells, albeit these approaches have yielded so far only moderate results. This is most likely due to our limited knowledge of the processes that ultimately regulate this form of cell death. In this proposal, we start by presenting the results of an unbiased cDNA overexpression screen aiming to identify genes able to fully complement the loss of GPX4. This approach allowed us to identify a yet-unrecognized oxidoreductase which fully prevents ferroptosis induced by GPX4 deletion or pharmacological inhibition. In this project, we thus aim to characterize how this enzyme is able to bypass the requirement for GPX4 on the molecular level. We will take advantage of a series of state-of-the art methodologies including CRISPR/Cas technology, metabolomics, (oxi) lipidomcis and chemical biology to shed light into the mechanistic details of this novel ferroptosis regulator. Moreover, the in vivo relevance of this pathway will also be assessed through the characterization of two novel mouse models based on the constitutive deletion or the conditional, tissue-specific overexpression of this oxidoreductase. We are convinced that the data generated here will essentially provide a better understanding of the metabolic liabilities sensitizing cells to ferroptosis. In addition, new opportunities will be uncovered to efficiently target this form of cell death with the ultimate goal to identify novel strategies to eradicate cancer cells resistant to standard therapy.