小分子抑制劑可有效抑制人線粒體DNA轉錄
作者：
小柯機器人發布時間：2020/12/17 13:51:54
德國馬克斯·普朗克衰老生物學研究所Nils-Gran Larsson和瑞典哥德堡大學Claes M. Gustafsson研究組合作，發現了人類線粒體DNA（mtDNA）轉錄的小分子抑制劑。該研究成果於2020年12月16日在線發表在國際學術期刊《自然》上。
研究人員發現了靶向人類線粒體RNA聚合酶（POLRMT）從而抑制線粒體轉錄（IMTs）的一線特異性抑制劑，POLRMT對於氧化磷酸化（OXPHOS）通路至關重要。在體外重組系統中IMT能有效抑制mtDNA轉錄，並在細胞系中產生劑量依賴性抑制mtDNA表達和OXPHOS的效果。為了驗證其在細胞中的分子靶點，研究人員對誘變的細胞進行了外顯子組測序，並在POLRMT中鑑定了引起IMT抗性的胺基酸取代簇。
研究人員解析了與IMT與 POLRMT結合的冷凍電鏡（cryo-EM）結構，該結構進一步確定了POLRMT活性中心裂附近的變構結合位點。先前的報導證明了癌細胞的生長和對治療有抗性癌症幹細胞的持久性取決於OXPHOS，因此研究人員檢測了IMT是否具有抗腫瘤作用。儘管IMT治療在人癌細胞的異種移植物中誘導了強烈的抗腫瘤反應，但小鼠可以耐受四周的口服IMT治療並且不會在正常組織中引起OXPHOS功能障礙或毒性。
綜上所述，IMT提供了一種強大而特定的化學生物學工具來研究mtDNA表達在生理和疾病中的作用。
據了解，線粒體DNA表達的改變發生在衰老和一系列人類疾病中（例如：先天性代謝錯誤、神經變性和癌症）。
附：英文原文
Title: Small-molecule inhibitors of human mitochondrial DNA transcription
Author: Nina A. Bonekamp, Bradley Peter, Hauke S. Hillen, Andrea Felser, Tim Bergbrede, Axel Choidas, Moritz Horn, Anke Unger, Raffaella Di Lucrezia, Ilian Atanassov, Xinping Li, Uwe Koch, Sascha Menninger, Joanna Boros, Peter Habenberger, Patrick Giavalisco, Patrick Cramer, Martin S. Denzel, Peter Nussbaumer, Bert Klebl, Maria Falkenberg, Claes M. Gustafsson, Nils-Gran Larsson
Issue&Volume: 2020-12-16
Abstract: Altered expression of mitochondrial DNA (mtDNA) occurs in ageing and a range of human pathologies (for example, inborn errors of metabolism, neurodegeneration and cancer). Here we describe first-in-class specific inhibitors of mitochondrial transcription (IMTs) that target the human mitochondrial RNA polymerase (POLRMT), which is essential for biogenesis of the oxidative phosphorylation (OXPHOS) system1,2,3,4,5,6. The IMTs efficiently impair mtDNA transcription in a reconstituted recombinant system and cause a dose-dependent inhibition of mtDNA expression and OXPHOS in cell lines. To verify the cellular target, we performed exome sequencing of mutagenized cells and identified a cluster of amino acid substitutions in POLRMT that cause resistance to IMTs. We obtained a cryo-electron microscopy (cryo-EM) structure of POLRMT bound to an IMT, which further defined the allosteric binding site near the active centre cleft of POLRMT. The growth of cancer cells and the persistence of therapy-resistant cancer stem cells has previously been reported to depend on OXPHOS7,8,9,10,11,12,13,14,15,16,17, and we therefore investigated whether IMTs have anti-tumour effects. Four weeks of oral treatment with an IMT is well-tolerated in mice and does not cause OXPHOS dysfunction or toxicity in normal tissues, despite inducing a strong anti-tumour response in xenografts of human cancer cells. In summary, IMTs provide a potent and specific chemical biology tool to study the role of mtDNA expression in physiology and disease.
DOI: 10.1038/s41586-020-03048-z
Source: https://www.nature.com/articles/s41586-020-03048-z