Drosophila melanogaster
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1066555 | ENA |
REPOSITORIES: ENA
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Project description:<p>Metabolic regulation is central to the tumor suppressor function of p53. Here we report that propionyl-CoA metabolic remodeling and epigenetic changes underpin p53-mediated restraint of autoimmunity through regulatory T (Treg) cells. By analyzing the human patients with autoimmune diseases, we found p53 expression was significantly reduced in Treg cells negatively correlating with abnormally elevated BCL-6 levels. p53 loss causes dysregulated immune homeostasis and dampens Tregs function in vitro and in vivo. Mechanistically, p53 transcriptionally activates ALDH6A1 expression and propionyl-CoA anabolism to upregulate functional Treg gene expression via histone propionylation. Treg-specific knockout of ALDH6A1 phenocopies the autoimmune responses of p53 deficiency, and propionyl-CoA restoration recovers Treg cell function in mice lacking p53 or ALDH6A1. Clinically, impaired p53-ALDH6A1-histone propionylation signaling is observed in AS and SLE patients and correlates with poor efficacy of first-line therapies in autoimmune patients. Together, these findings reveal a directly connection between propionyl-CoA metabolism and epigenetic changes, which is governed by p53 and is crucial for Treg cell function and immune tolerance suppression.</p>
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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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Project description:Small RNAs derived from mature tRNAs, referred to as tRNA fragments or “tRFs”, are an emerging class of regulatory RNAs with poorly understood functions in cellular regulation. We recently identified a role for one specific tRF – 5’ tRF-Gly-GCC, or tRF-GG – in repression of genes associated with the endogenous retroelement MERVL, but the mechanistic basis for this regulation was unknown. Here, we show that tRF-GG plays a role in production of a wide variety of noncoding RNAs normally synthesized in Cajal bodies. Among these noncoding RNAs, tRF-GG regulation of the U7 snRNA modulates heterochromatin-mediated transcriptional repression of MERVL elements by supporting an adequate supply of histone proteins. Importantly, the effects of inhibiting tRF-GG on histone mRNA levels, activity of a histone 3’ UTR reporter, and ultimately on MERVL regulation could all be suppressed by the U7 RNA. We show that the related RNA-binding proteins hnRNPF and H bind directly to tRF-GG, and are required for Cajal body biogenesis. Together, our data reveal a conserved mechanism for 5’ tRNA fragment control of noncoding RNA biogenesis and, consequently, in global chromatin organization.
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Project description:tRNA fragments (tRFs) are small non-coding RNA molecules that are generated through the cleavage of tRNAs and have been implicated in various biological processes. Among the different types of tRFs, the 3′-tRFs have attracted considerable scientific interest due to their regulatory role in gene expression. In this study, we investigated the role of 3′-tRF-CysGCA, a tRF derived from cleavage in the T-loop of tRNACysGCA, in the regulation of gene expression in HEK-293 cells. Previous studies have shown that 3′-tRF-CysGCA is incorporated into the RISC complex and interacts with Argonaute proteins, suggesting its involvement in the regulation of gene expression. However, the general role and effect of the deregulation of 3′-tRF-CysGCA levels in human cells have not been investigated so far. To address this gap, we stably overexpressed 3′-tRF-CysGCA in HEK-293 cells and performed transcriptomics and proteomics experiments. Moreover, we validated the interaction of this tRF with putative targets whose levels were affected after 3′-tRF-CysGCA overexpression. Last, we investigated the implication of 3′-tRF-CysGCA in various pathways using extensive bioinformatics analysis. Our results indicate that 3′-tRF-CysGCA overexpression led to changes in the cell expression profile, and we identified multiple pathways that were affected by the deregulation of this tRF. Additionally, our reporter assays demonstrated that 3′-tRF-CysGCA directly interacted with TMPO and ERGIC1, leading to changes in their expression levels. Taken together, these findings suggest that 3′-tRF-CysGCA plays a significant role in the regulation of gene expression and highlight the potential importance of this tRF in cellular processes.
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