MicroRNA Directly Enhances Mitochondrial Translation during Muscle Differentiation.
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE57596 | GEO | 2014/08/01
SECONDARY ACCESSION(S): PRJNA246750
REPOSITORIES: GEO
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Project description:MicroRNAs are well known to mediate translational repression and mRNA degradation in the cytoplasm. Various microRNAs have also been detected in membrane-compartmentalized organelles, but the functional significance has remained elusive. Here we report that miR-1, a microRNA specifically induced during myogenesis, efficiently enters the mitochondria where it unexpectedly stimulates, rather than represses, the translation of specific mitochondrial genome-encoded transcripts. We show that this positive effect requires specific miR:mRNA base-pairing and Ago2, but not its functional partner GW182, which is excluded from the mitochondria. We provide evidence for the direct action of Ago2 in mitochondrial translation by Ago2 CrossLinking ImmunoPrecipitation coupled with sequencing (CLIP-seq), functional rescue with mitochondria-targeted Ago2, and selective inhibition of the microRNA machinery in the cytoplasm. These findings unveil a positive function of microRNA in mitochondrial translation and suggest a highly coordinated myogenic program via miR-1 mediated translational stimulation in the mitochondria and repression in the cytoplasm. Examination of miRNA's regulation function in mitochondria in C2C12 myoblasts cells and myotubes cells with CLIP-seq (Ago2).
2014-08-01 | E-GEOD-57596 | biostudies-arrayexpress
Project description:The liver-specific microRNA, miR-122, is an essential host factor for replication of hepatitis C virus (HCV), an important infectious cause of chronic liver disease and hepatocellular carcinoma. miR-122 stabilizes the positive-strand HCV RNA genome and promotes viral RNA synthesis by binding two closely spaced sites (S1 and S2) near the 5’ end of the genome in association with Ago2. Ago2 is essential for both host factor activities, but whether other host proteins are involved is unknown. Using a quantitative proteomics approach, we identified TNRC6A (GW182) and its paralogs (TNRC6B and TNRC6C), as functionally important components of the miR-122/Ago2 host factor complex binding HCV RNA. Depletion of any two TNRC6 proteins reduced HCV replication in Huh-7.5 cells,but did not reduce viral RNA stability or translational activity, but rather dampened miR-122 stimulation of viral RNA synthesis. However, TNRC6 depletion had no effect on replication of HCV in which S2 was mutated so that miR-122 binds only S1, whereas it significantly enhanced replication when S1 was mutated and only S2 bound by miR-122. Consistent with this, we found that TNRC6 proteins preferentially associate with the S1 site, and that the association of Ago2 with S2 is increased in TNRC6-depleted cells. Collectively, these data suggest a model in which TNRC6 proteins, which are known to interact with Ago2, preferentially direct the miR-122/Ago2 complex to S1 while restricting its association with S2, thereby fine tuning the spatial organization of miR-122/Ago2 complexes bound to the viral RNA.
2019-04-24 | PXD013054 | Pride
Project description:Slowing down mRNA translation in either the cytoplasm or the mitochondria are both conserved longevity mechanisms. Here, we found a non-interventional natural correlation of mitochondrial and cytoplasmic ribosomal proteins when looking at mouse population genetics, suggesting a mito-cytoplasmic translational balance. Additionally, inhibiting mitochondrial translation in C. elegans in turn reduced cytoplasmic translation and repressed growth pathways while upregulating stress responses at both proteome and transcriptome levels. This coordinated repression of cytoplasmic translation is dependent on the atf-5/Atf4 transcription factor and is conserved in mammalian cells upon inhibiting mitochondrial translation pharmacologically with the antibiotic doxycycline. Lastly, extending this to a mammalian setting using doxycycline-treated germ-free mice, we found repressed cytoplasmic translation and ribosomal proteins in liver. These data demonstrate that inhibiting mitochondrial translation initiates a signaling cascade leading to coordinated repression of cytoplasmic translation, unlike previously described unidirectional cyto-to-mito translational communication in yeast, which can be targeted to promote healthy aging.
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Project description:MicroRNAs (miRNAs) are small non-coding RNAs that associate with Argonaute 2 protein to regulate gene expression at the post-transcriptional level in the cytoplasm. However, recent studies have reported that some miRNAs localize to and function in other cellular compartments. Mitochondria harbour their own genetic system that may be a potential site for miRNA-mediated post-transcriptional regulation. We aimed at investigating whether nuclear-encoded miRNAs can localize to and function in human mitochondria. To enable identification of mitochondrial-enriched miRNAs, we profiled the mitochondrial and cytosolic RNA fractions from the same HeLa cells by miRNA microarray analysis. Mitochondria were purified using a combination of cell fractionation and immunoisolation, and assessed for the lack of protein and RNA contaminants. We found 57 miRNAs differentially expressed in HeLa mitochondria and cytosol. Of these 57, a signature of 13 nuclear-encoded miRNAs was reproducibly enriched in mitochondrial RNA and validated by RT-PCR for hsa-miR-494, hsa-miR-1275 and hsa-miR-1974. This study provides the first comprehensive view of the localization of RNA interference components to the mitochondria. Our data outline the molecular bases for a novel layer of crosstalk between nucleus and mitochondria through a specific subset of human miRNAs that we termed ‘mitomiRs’. To assess whether nuclear-encoded miRNA are detectable in human mitochondria, we performed the following four steps approach. First, cultured HeLa cells were allowed to reach 80-100% confluence and subjected to fractionation in order to isolate the cytosolic fraction. From the same HeLa cells, mitochondria were isolated by immunomagnetic Anti-TOM22 MicroBeads from the Mitochondria Isolation Kit (Miltenyi Biotec). In total, six mitochondria preparations were perfromed, three of these were additionally treated with RNase A. Second, total RNA was extracted from the mitochondrial and cytosolic fractions. Third, mitochondrial and cytosolic RNA were respectively profiled by microRNA microarray analysis. Last, data were analyzed and normalized.Three independent assays were performed.
2011-10-05 | E-GEOD-24761 | biostudies-arrayexpress
Project description:Current evidence suggests that nuclear-encoded mitochondrial proteins can be locally translated at the mitochondrial surface and co-translationally or post-translationally imported into mitochondria. mRNA localization on the mitochondrial membrane, a prerequisite for localized translation, remains uncharacterized in higher eukaryotic organisms. We employed fractionation-sequencing to profile mitochondria-associated mRNAs in zebrafish larvae. Our transcriptome-wide analysis reveals the localization of mRNAs of only 12% of the nuclear-encoded mitochondrial proteins to the mitochondrial surface, which suggests that post-translational import is the dominant mode of protein import to mitochondria. Additionally, the mRNAs which were localized to the mitochondrial membrane consisted mostly of those encoding proteins involved in mitochondrial dynamics, suggesting their site-specific translation. Finally, we show that the loss of function of the MIA pathway responsible for the post-translational import of a subclass of mitochondrial proteins, triggers mitochondrial localization of mRNAs encoding proteins that are imported to mitochondria via other pathways. Thus, our study suggests that mRNA targeting and localized translation could be relevant in higher eukaryotes to combat stress conditions affecting mitochondrial biogenesis in general.
2023-10-28 | GSE160355 | GEO
Project description:When adapting to environmental stress, cells attenuate and reprogram their translational output. In part, these altered translation profiles are established through changes in the interactions between RNA-binding proteins and mRNAs. The Ago2/microRNA machinery has been shown to participate in stress-induced translational upregulation of a particular mRNA, CAT-1; however, a detailed, transcriptome-wide understanding of the involvement of Ago2 in the process has been lacking. Here, we profiled the overall changes in Ago2-mRNA interactions upon arsenite stress by CLIP-seq. Ago2 displayed a significant remodeling of its transcript occupancy, with the majority of 3` UTR and CDS sites exhibiting stronger interaction. Interestingly, target sites that were destined for release from Ago2 upon stress were depleted in miRNA complementarity signatures, suggesting an alternative mode of interaction. To compare the changes in Ago2 binding patterns across transcripts with changes in their translational states, we measured mRNA profiles on ribosome/polysome gradients by RNA-seq. Increased Ago2 occupancy correlated with stronger repression of translation for those mRNAs, as evidenced by a shift toward lighter gradient fractions upon stress, while release of Ago2 was associated with the limited number of transcripts that remained translated. Taken together, these data point to a role for Ago2 and the mammalian microRNAs in mediating the translational component of the stress response. In this sub-series, RNAseq data from sucrose gradient fractions with arsenite treatment are presented.
2013-07-15 | E-GEOD-44379 | biostudies-arrayexpress
Project description:Background: The RNA-binding protein Argonaute 2 (AGO2) is a key effector of RNAsilencing pathways, exerting a pivotal role in microRNA maturation and activity, that in the cell nucleus is able to modulate chromatin remodeling, transcriptional gene regulation and RNA splicing. The Estrogen Receptor beta (ERβ), a member of the nuclear receptor superfamily of trancriptional regulators, is endowed with oncosuppressive activities, antagonizing hormone-induced carcinogenesis and inhibiting growth and oncogenic functions in luminal-like breast cancers (BCs), where its expression correlates with a better prognosis of the disease. Results: Applying interaction proteomics coupled to mass spectrometry (MS) to characterize nuclear factors cooperating with ERβ in gene regulation, we identified AGO2 as a novel partner of ERβ in human BC cells. ERβ-AGO2 association was confirmed in vitro and in vivo both in the nucleus and cytoplasm. ChIP-Seq demonstrated AGO2 association to a large number of ERβ binding sites, and total and nascent RNA-Seq in ERβ+ vs ERβ- cells, and before and after AGO2 knock-down in ERβ+ cells, revealed a widespread involvement of this factor in ERβ-mediated regulation of gene transcription rate and RNA splicing. Moreover, isolation and sequencing by RIP-Seq of ERβ-associated long and small RNAs in the cytoplasm suggested involvement of the nuclear receptor in RISC loading, indicating that it may able to control directly also mRNA translation efficiency and stability. Conclusions: These results demonstrate that AGO2 is a pleiotropic functional partner of ERβ in BC cells, indicating that both factors are endowed with multiple roles in the control of BC cell functions.
2017-09-20 | PXD006280 | Pride
Project description:Argonaute 2 (AGO2), the catalytic engine of RNAi, is typically associated with inhibition of translation in the cytoplasm. Contrary to dogma, AGO2 has also been implicated in nuclear processes including transcription and splicing. There has been little insight into AGO2's nuclear interactions or how they might differ relative to cytoplasm. Here we investigate the interactions of cytoplasmic and nuclear AGO2 using semi-quantitative mass spectrometry. Mass spectrometry often reveals long lists of candidate proteins, complicating efforts to rigorously discriminate true interacting partners from artifacts. We prioritized candidates using orthogonal analytical strategies that compare replicate mass spectra of proteins associated with FLAG-tagged and endogenous AGO2. Interactions with TRNC6A, TRNC6B, TNRC6C, and AGO3 are conserved between nuclei and cytoplasm. TAR binding protein interacted stably with cytoplasmic AGO2 but not nuclear AGO2, consistent with strand loading in the cytoplasm. Our data suggest that the core RNAi machinery is conserved between the nucleus and cytoplasm but that accessory proteins differ. Orthogonal analysis of mass spectra is a powerful approach to streamlining identification of protein partners.
2016-02-11 | MSV000079508 | MassIVE
Project description:MicroRNAs are small non-coding RNA molecules mediating the translational repression and degradation of target mRNAs in the cell. Mature miRNAs are used as a template by the RNA-induced silencing complex (RISC) to recognize the complementary mRNAs to be regulated. To discern further RISC complex functions, we analyzed the activities of two RISC proteins, AGO2 and GW182, in the MCF-7 human breast cancer cell line. We performed three RIP-Chip experiments using either anti-AGO2 or anti-GW182 antibody and compiled a dataset made up of the miRNA and mRNA expression profiles of three samples for each experiment. Specifically, we analyzed the input sample, the immunoprecipitated fraction and the unbound sample resulting from the RIP experiment. We used the expression profile of the input sample to compute several variables, using formulae capable of integrating the information on predicted miRNA binding sites, both in the 3’UTR and coding regions, with miRNA and mRNA expression level profiles. We compared immunoprecipitated vs unbound samples to determine the differentially expressed genes, independently for AGO2 and GW182 related samples. For each of the two proteins, we trained and tested several support vector machine algorithms able to predict the differentially expressed genes that were experimentally detected. The most efficient algorithm for predicting the over-expressed genes in AGO2 immunoprecipitated samples was trained by using variables involving the number of binding sites in both the 3’UTR and coding region, integrated with the miRNA expression profile, as expected for miRNA targets. On the other hand, we found that the best variable for predicting over-expressed genes in the GW182 immunoprecipitated sample was the length of the coding region. Due to the major role of GW182 in GW/P-bodies, our data suggests that the AGO2-GW182 RISC complex recruits genes based on miRNA binding sites in the 3’UTR and coding region, but only the longer mRNAs remain sequestered in GW/P-bodies, functioning as a repository for translationally silenced RNAs.
2018-09-05 | GSE109666 | GEO
Project description:MicroRNAs are small non-coding RNA molecules mediating the translational repression and degradation of target mRNAs in the cell. Mature miRNAs are used as a template by the RNA-induced silencing complex (RISC) to recognize the complementary mRNAs to be regulated. To discern further RISC complex functions, we analyzed the activities of two RISC proteins, AGO2 and GW182, in the MCF-7 human breast cancer cell line. We performed three RIP-Chip experiments using either anti-AGO2 or anti-GW182 antibody and compiled a dataset made up of the miRNA and mRNA expression profiles of three samples for each experiment. Specifically, we analyzed the input sample, the immunoprecipitated fraction and the unbound sample resulting from the RIP experiment. We used the expression profile of the input sample to compute several variables, using formulae capable of integrating the information on predicted miRNA binding sites, both in the 3’UTR and coding regions, with miRNA and mRNA expression level profiles. We compared immunoprecipitated vs unbound samples to determine the differentially expressed genes, independently for AGO2 and GW182 related samples. For each of the two proteins, we trained and tested several support vector machine algorithms able to predict the differentially expressed genes that were experimentally detected. The most efficient algorithm for predicting the over-expressed genes in AGO2 immunoprecipitated samples was trained by using variables involving the number of binding sites in both the 3’UTR and coding region, integrated with the miRNA expression profile, as expected for miRNA targets. On the other hand, we found that the best variable for predicting over-expressed genes in the GW182 immunoprecipitated sample was the length of the coding region. Due to the major role of GW182 in GW/P-bodies, our data suggests that the AGO2-GW182 RISC complex recruits genes based on miRNA binding sites in the 3’UTR and coding region, but only the longer mRNAs remain sequestered in GW/P-bodies, functioning as a repository for translationally silenced RNAs.
2018-09-05 | GSE109665 | GEO