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Demethylzeylasteral inhibits oxidative phosphorylation complex biogenesis by targeting LRPPRC in lung cancer

ABSTRACT: Targeted inhibition of mitochondrial oxidative phosphorylation (OXPHOS) complex generation is an emerging and promising cancer treatment strategy, but limited targets and specific inhibitors have been reported. Leucine-rich pentatricopeptide repeat-containing protein (LRPPRC) is an atypical RNA-binding protein that regulates the stability of all 13 mitochondrial DNA-encoded mRNA (mt-mRNA) and thus participates in the synthesis of the OXPHOS complex. LRPPRC is also a prospective therapeutic target for lung adenocarcinoma, serving as a promising target for OXPHOS inhibition. In this study, we identified Demethylzeylasteral (T-96), a small molecule extracted from the Chinese herb Tripterygium wilfordii Hook. f., as a novel inhibitor of LRPPRC. T-96 directly bound to the RNA-binding domain of LRPPRC, inhibiting its interaction with mt-mRNA. This led to instability in both mt-mRNA and LRPPRC protein. Treatment with T-96 significantly reduced the mRNA and protein levels of the OXPHOS complex. As a consequence of LRPPRC inhibition, T-96 treatment induced a defect in the synthesis of the OXPHOS complex, inhibiting mitochondrial aerobic respiration and ATP synthesis. Moreover, T-96 exhibited potent antitumor activity for lung adenocarcinoma in vitro and in vivo, and the antitumor effect of T-96 was dependent on LRPPRC expression. In conclusion, this study not only identified the first traditional Chinese medicine monomer inhibitor against OXPHOS complex biosynthesis as well as a novel target of Demethylzeylasteral, but also shed light on the unique antitumor mechanism of bioactive compounds derived from traditional Chinese medicine.

ORGANISM(S): Homo sapiens

PROVIDER: GSE279114 | GEO | 2024/10/09

REPOSITORIES: GEO

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Project description:Background: Transcription control of mitochondrial metabolism is essential for cellular function. A better understanding of this process will aid the elucidation of mitochondrial disorders, in particular of the many genetically unsolved cases of oxidative phosphorylation (OXPHOS) deficiency. Yet, to date only few studies have investigated nuclear gene regulation in the context of OXPHOS deficiency. In this study, we combined RNA sequencing of human complex I-deficient patient cells across 32 conditions of perturbed mitochondrial metabolism, with a comprehensive analysis of gene expression patterns, co-expression calculations and transcription factor binding sites. Results: Our analysis shows that OXPHOS genes have a significantly higher co-expression with each other than with other genes, including mitochondrial genes. We found no evidence for complex-specific mRNA expression regulation in the tested cell types and conditions: subunits of different OXPHOS complexes are similarly (co-)expressed and regulated by a common set of transcription factors. However, we did observe significant differences between the expression of OXPHOS complex subunits compared to assembly factors, suggesting divergent transcription programs. Furthermore, complex I co-expression calculations identified 684 genes with a likely role in OXPHOS biogenesis and function. Analysis of evolutionarily conserved transcription factor binding sites in the promoters of these genes revealed almost all known OXPHOS regulators (including GABP, NRF1/2, SP1, YY1, E-box factors) and a set of six yet uncharacterized candidate transcription factors (ELK1, KLF7, SP4, EHF, ZNF143, and EL2). Conclusions: OXPHOS genes share an expression program distinct from other mitochondrial genes, indicative of targeted regulation of this mitochondrial sub-process. Within the subset of OXPHOS genes we established a difference in expression between subunits and assembly factors. Most transcription regulators of genes that co-express with complex I are well-established factors for OXPHOS biogenesis. For the remaining six factors we here suggest for the first time a link with transcription regulation in OXPHOS deficiency. RNA-SEQ of whole cell RNA in 2 control and 2 complex I deficient patient fibroblast cell lines treated with 4 compounds in duplicate, resulting in a total of 2x2x4x2=32 samples

Project description:In this study, we discovered cytosolic and mitochondrial fragments resulting from tRNA and mt-tRNA cleavage, which may act as new regulators of cellular and metabolic functions. We selected the mt-tRF-LeuTAA fragment derived from a tRNA encoded by the mitochondrial genome for further investigation, as its level is reduced in the islets of diabetes-susceptible animal models, while being abundant in ß-cells. mt-tRF-LeuTAA fragment is derived from the cleavage of tRNA-LeuTAA encoded by the mitochondrial genome. We demonstrated that mt-tRF-LeuTAA acts as a key regulator of mitochondrial OXPHOS functions, mitochondrial membrane potential, the insulin secretory capacity of ß-cells, and the insulin sensitivity of myotube muscle cells. We sought to investigate the downstream mechanisms activated by this fragment. To gain a comprehensive understanding, we conducted proteomic analyses on rat islets with silenced mt-tRF-LeuTAA for 72 hours. Inhibiting mt-tRF-LeuTAA led to significant differential expression of 642 proteins, cut-off adjusted p ≤ 0.05. To further investigate the cellular rearrangement associated with the inhibition of mt-tRF-LeuTAA, we conducted enrichment analysis using Gene Ontology Molecular Function terms on mass spectrometry data. At the protein level, there was a significant enrichment of mitochondrial pathways, such as oxidoreductase activity, ATPase activity, hydrogen transport, NADH dehydrogenase activity, cytochrome-c oxidase activity, and oxygen transport. To elucidate the mechanisms by which mt-tRF-LeuTAA operates, we also conducted pull-down experiments in insulin-secreting INS832/13 cells, followed by mass spectrometry using 3'-biotinylated mimic sequence oligonucleotides of mt-tRF-LeuTAA. Our analysis unveiled interactions between mt-tRF-LeuTAA and 24 proteins, meeting the criteria of a fold change ≥ 6 and an adjusted p-value ≤ 0.05. Notably, among these proteins, 13 are localized within the mitochondria and play significant roles in mitochondrial oxidative functions. Some of these key proteins include Suclg2, Nme3, Sdha, Lrpprc, and Ndufa12. Pathway enrichment analysis of the binding partners associated with the mitochondrial fragment mt-tRF-LeuTAA indicates an over-representation of signaling pathways crucial to maintaining mitochondrial metabolism. These pathways include oxidative phosphorylation (OXPHOS), ROS-induced stress responses, the tricarboxylic acid (TCA) cycle, calcium homeostasis regulation, lipid metabolism, RNA splicing, and mitochondrial import, which all contribute fundamentally to the maintenance of mitochondrial metabolism. These findings collectively provide insights into the essential mechanisms underlining the functionality of mitochondrially-encoded tRNA-derived fragments with the view to sustaining mitochondrial metabolism.

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Demethylzeylasteral inhibits oxidative phosphorylation complex biogenesis by targeting LRPPRC in lung cancer

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