Cell Fate Safeguarding by the Mitochondrial Dehydrogenase IDH3 via linked Metabolism and Epigenetic Pathways in C. elegans.

线虫中线粒体脱氢酶 IDH3 通过关联的代谢和表观遗传途径保护细胞命运。

• 批准号: 450249199
• 负责人: Professor Dr. Baris Tursun
• 金额: --
• 依托单位: Abteilung für Molekulare Zellbiologie der Tiere
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/450249199?language=en
• 关键词: Cell; Fate; Safeguarding; Mitochondrial; Dehydrogenase

Prospective tissue replacement therapies require specific cell types to replenish and repair diseased organs of patients. For instance, healthy neuronal cells could regenerate brain tissues of Alzheimer’s patients. One promising source for new healthy cells is to convert the identity of abundantly available cells such as astrocytes or fibroblasts. Cell type conversion is achieved by reprogramming, which requires overexpression of specific transcription factors. However, transcription factors are usually restricted in their efficiency to induce reprogramming due to cell fate safeguarding mechanisms. While much is known about how cell fates are specified during development, cellular maintenance and safeguarding mechanisms are not fully understood. This, however, is essential to improve cellular reprogramming for future regenerative medicine applications. We previously demonstrated that the nematode C. elegans is a powerful model organism to identify evolutionarily conserved safeguarding mechanisms of cells (Müthel et al., 2019 AgingCell; Hajduskova et al., 2019 Genetics; Kolundzic et al., 2018 DevCell; Seelk et al., 2016 eLife; Tursun et al., 2011 Science). Using reverse genetics, we now identified the conserved mitochondrial isocitrate dehydrogenase IDH3 as a barrier for reprogramming germ cells into neurons. This unexpected barrier is critical for metabolism, raising the question of how perturbations in mitochondria create permissiveness for cell fate conversion. Our preliminary results indicate that IDH3 depletion causes impaired gene expression regulation by decreasing repressive chromatin. Yet, how signaling pathways integrate metabolic states to elicit epigenetic changes is not well understood. This research proposal aims at deciphering molecular pathways, which link metabolism and epigenetics to maintain cell states and counteract reprogramming. To elucidate relevant molecular processes, we are combining genetics, cell-specific transcriptomics (RNA-Seq), and chromatin accessibility assays (ATAC-Seq) with spectrometry-based analysis of metabolites. Strikingly, we also encountered non-cell-autonomous effects upon IDH3 depletion, indicating that other tissues contribute to germ cell fate safeguarding. Knowledge about non-cell-autonomous effects is essential for future regenerative medicine as they can have opposing effects in vitro vs. in vivo. Therefore, the use of living animals to study cellular safeguarding and reprogramming can reveal critical cellular and trans-tissue pathways that affect cell fate plasticity in the physiological context of intact tissues. Overall, knowledge about non-cell-autonomous effects of metabolic and epigenetic gene expression regulation is fundamental to improve reprogramming for future tissue replacement applications.

前瞻性的组织替代疗法需要特定的细胞类型来补充和修复患者的病变器官。例如，健康的神经元细胞可以使阿尔茨海默病患者的脑组织再生。新的健康细胞的一个有希望的来源是转换大量可用细胞的身份，如星形胶质细胞或成纤维细胞。细胞类型转换是通过重编程实现的，这需要特异性转录因子的过表达。然而，由于细胞命运保护机制，转录因子诱导重编程的效率通常受到限制。虽然我们对细胞命运在发育过程中是如何被指定的了解很多，但细胞的维护和保护机制还没有完全被理解。然而，这对于改善细胞重编程以用于未来的再生医学应用至关重要。我们之前已经证明线虫秀丽隐杆线虫是一种识别细胞进化保守保护机制的强大模式生物（m<s:1> thel等人，2019 AgingCell； Hajduskova等人，2019 Genetics； Kolundzic等人，2018 DevCell； Seelk等人，2016 eLife； Tursun等人，2011 Science）。利用反向遗传学，我们现在确定了保守的线粒体异柠檬酸脱氢酶IDH3作为生殖细胞重编程为神经元的屏障。这种意想不到的障碍对新陈代谢至关重要，这就提出了一个问题，即线粒体的扰动是如何为细胞命运的转变创造容错性的。我们的初步结果表明，IDH3缺失通过减少抑制染色质导致基因表达调控受损。然而，信号通路如何整合代谢状态以引发表观遗传变化尚不清楚。本研究计划旨在破解连接代谢和表观遗传学以维持细胞状态和抵消重编程的分子途径。为了阐明相关的分子过程，我们将遗传学、细胞特异性转录组学（RNA-Seq）和染色质可及性分析（ATAC-Seq）与基于光谱的代谢物分析相结合。引人注目的是，我们还遇到了IDH3耗竭的非细胞自主效应，这表明其他组织也参与了生殖细胞命运的保护。了解非细胞自主效应对未来的再生医学至关重要，因为它们在体外和体内可能具有相反的作用。因此，利用活体动物研究细胞保护和重编程可以揭示在完整组织的生理背景下影响细胞命运可塑性的关键细胞和跨组织途径。总的来说，了解代谢和表观遗传基因表达调控的非细胞自主效应是改善未来组织替代应用的重编程的基础。