scholarly journals Microtubule disruption targets HIF-1α mRNA to cytoplasmic P-bodies for translational repression

2011 ◽  
Vol 192 (1) ◽  
pp. 83-99 ◽  
Author(s):  
Marisa Carbonaro ◽  
Aurora O'Brate ◽  
Paraskevi Giannakakou
Keyword(s):  
Solid Tumors ◽  
Cell Biology ◽  
Messenger Rna ◽  
Hypoxia Inducible Factor ◽  
Translational Repression ◽  
P Bodies ◽  
Argonaute 2 ◽  
Microtubule Disruption ◽  
Significant Enrichment ◽  
Body Component

The hypoxia inducible factor 1α (HIF-1α) is overexpressed in solid tumors, driving tumor angiogenesis and survival. However, the mechanisms regulating HIF-1α expression in solid tumors are not fully understood. In this study, we find that microtubule integrity and dynamics are intricately involved in orchestrating HIF-1α translation. HIF-1α messenger RNA (mRNA) traffics on dynamic microtubules when it is actively translated. Microtubule perturbation by taxol (TX) and other microtubule-targeting drugs stalls HIF-1α mRNA transport and releases it from polysomes, suppressing its translation. Immunoprecipitation of the P-body component Argonaute 2 (Ago2) after microtubule disruption shows significant enrichment of HIF-1α mRNAs and HIF-targeting microRNAs (miRNAs). Inhibition of HIF-repressing miRNAs or Ago2 knockdown abrogates TX’s ability to suppress HIF-1α translation. Interestingly, microtubule repolymerization after nocodazole washout allows HIF-1α mRNA to reenter active translation, suggesting that microtubule dynamics exert tight yet reversible control over HIF-1α translation. Collectively, we provide evidence for a new mechanism of microtubule-dependent HIF-1α translation with important implications for cell biology.

scholarly journals Mammalian GW220/TNGW1 is essential for the formation of GW/P bodies containing miRISC

2012 ◽  
Vol 198 (4) ◽  
pp. 529-544 ◽  
Author(s):  
Virginia Castilla-Llorente ◽  
Lee Spraggon ◽  
Miwako Okamura ◽  
Saif Naseeruddin ◽  
Matthew Adamow ◽  
...  
Keyword(s):  
Gene Expression ◽  
Messenger Rna ◽  
Cellular Localization ◽  
Translational Repression ◽  
P Bodies ◽  
Target Mrna ◽  
Core Components ◽  
Mirna Pathway

The microRNA (miRNA)-induced silencing complex (miRISC) controls gene expression by a posttranscriptional mechanism involving translational repression and/or promoting messenger RNA (mRNA) deadenylation and degradation. The GW182/TNRC6 (GW) family proteins are core components of the miRISC and are essential for miRNA function. We show that mammalian GW proteins have distinctive functions in the miRNA pathway, with GW220/TNGW1 being essential for the formation of GW/P bodies containing the miRISC. miRISC aggregation and formation of GW/P bodies sequestered and stabilized translationally repressed target mRNA. Depletion of GW220 led to the loss of GW/P bodies and destabilization of miRNA-targeted mRNA. These findings support a model in which the cellular localization of the miRISC regulates the fate of the target mRNA.

scholarly journals Localization of Double-stranded Small Interfering RNA to Cytoplasmic Processing Bodies Is Ago2 Dependent and Results in Up-Regulation of GW182 and Argonaute-2

2009 ◽  
Vol 20 (1) ◽  
pp. 521-529 ◽  
Author(s):  
Aarti Jagannath ◽  
Matthew J.A. Wood
Keyword(s):  
Small Interfering Rna ◽  
Protein Complexes ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Mrna Translation ◽  
Processing Bodies ◽  
P Bodies ◽  
Argonaute 2 ◽  
Body Component ◽  
Interfering Rna

Processing bodies (P-bodies) are cytoplasmic foci implicated in the regulation of mRNA translation, storage, and degradation. Key effectors of microRNA (miRNA)-mediated RNA interference (RNAi), such as Argonaute-2 (Ago2), miRNAs, and their cognate mRNAs, are localized to these structures; however, the precise role that P-bodies and their component proteins play in small interfering RNA (siRNA)-mediated RNAi remains unclear. Here, we investigate the relationship between siRNA-mediated RNAi, RNAi machinery proteins, and P-bodies. We show that upon transfection into cells, siRNAs rapidly localize to P-bodies in their native double-stranded conformation, as indicated by fluorescence resonance energy transfer imaging and that Ago2 is at least in part responsible for this siRNA localization pattern, indicating RISC involvement. Furthermore, siRNA transfection induces up-regulated expression of both GW182, a key P-body component, and Ago2, indicating that P-body localization and interaction with GW182 and Ago2 are important in siRNA-mediated RNAi. By virtue of being centers where these proteins and siRNAs aggregate, we propose that the P-body microenvironment, whether as microscopically visible foci or submicroscopic protein complexes, facilitates siRNA processing and siRNA-mediated silencing through the action of its component proteins.

scholarly journals Ischemia Is Related to Tumour Genetics in Uveal Melanoma

Cancers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1004 ◽  
Author(s):  
Niels J. Brouwer ◽  
Annemijn P. A. Wierenga ◽  
Gülçin Gezgin ◽  
Marina Marinkovic ◽  
Gregorius P. M. Luyten ◽  
...  
Keyword(s):  
Uveal Melanoma ◽  
Messenger Rna ◽  
Tumour Size ◽  
Hypoxia Inducible Factor ◽  
The Cancer Genome Atlas ◽  
Basal Diameter ◽  
Von Hippel Lindau ◽  
The Status ◽  
Using Data ◽  
Tumour Genetics

Hypoxia-inducible factor 1-alpha (HIF1a) and its regulator von Hippel–Lindau protein (VHL) play an important role in tumour ischemia. Currently, drugs that target HIF1a are being developed to treat malignancies. Although HIF1a is known to be expressed in uveal melanoma (UM), it is as yet unknown which factors, such as tumour size or genetics, determine its expression. Therefore, we aimed to determine which tumour characteristics relate to HIF1a expression in UM. Data from 64 patients who were enucleated for UM were analysed. Messenger RNA (mRNA) expression was determined with the Illumina HT-12 v4 chip. In 54 cases, the status of chromosomes 3 and 8q, and BRCA1-associated protein 1 (BAP1) protein expression (immunohistochemistry) were determined. Findings were corroborated using data of 80 patients from the Cancer Genome Atlas (TCGA) study. A significantly increased expression of HIF1a, and a decreased expression of VHL were associated with monosomy 3/loss of BAP1 expression. The relationship between BAP1 loss and HIF1a expression was independent of chromosome 3. The largest basal diameter and tumour thickness showed no relationship with HIF1a. HIF1a expression related to an increased presence of infiltrating T cells and macrophages. From this study, we conclude that HIF1a is strongly related to tumour genetics in UM, especially to loss of BAP1 expression, and less to tumour size. Tumour ischemia is furthermore related to the presence of an inflammatory phenotype.

scholarly journals microRNA-Mediated Messenger RNA Deadenylation Contributes to Translational Repression in Mammalian Cells

PLoS ONE ◽  
2009 ◽  
Vol 4 (8) ◽  
pp. e6783 ◽  
Author(s):  
Traude H. Beilharz ◽  
David T. Humphreys ◽  
Jennifer L. Clancy ◽  
Rolf Thermann ◽  
David I. K. Martin ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Mammalian Cells ◽  
Translational Repression

scholarly journals MOV10 facilitates messenger RNA decay in an N6-methyladenosine (m6A) dependent manner to maintain the mouse embryonic stem cells state

2021 ◽  
Author(s):  
Majid Mehravar ◽  
Yogesh Kumar ◽  
Moshe Olshansky ◽  
Dhiru Bansal ◽  
Craig Dent ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Cell Biology ◽  
Messenger Rna ◽  
Mrna Decay ◽  
Embryonic Stem ◽  
Mouse Embryonic Stem Cells ◽  
Beta Catenin ◽  
Dependent Manner ◽  
Leukaemia Virus

N6-methyladenosine (m6A) is the most predominant internal mRNA modification in eukaryotes, recognised by its reader proteins (so-called m6A-readers) for regulating subsequent mRNA fates, such as splicing, export, localisation, decay, stability, and translation to control several biological processes. Although a few m6A-readers have been identified, yet the list is incomplete. Here, we identify a new m6A-reader protein, Moloney leukaemia virus 10 homologue (MOV10), in mouse embryonic stem cells (mESCs). MOV10 recognises m6A-containing mRNAs with a conserved GGm6ACU motif. Mechanistic studies uncover that MOV10 facilitates mRNA decay of its bound m6A- containing mRNAs in an m6A-dependent manner within the cytoplasmic processing bodies (P-bodies). Furthermore, MOV10 decays the Gsk-3beta mRNA through m6A that stabilises the BETA-CATENIN expression of a WNT/BETA-CATENIN signalling pathway to regulate downstream NANOG expression for maintaining the mESC state. Thus, our findings reveal how a newly identified m6A-reader, MOV10 mediates mRNA decay via m6A that impact embryonic stem cell biology.

scholarly journals P-bodies and the miRNA pathway regulate translational repression of bicoid mRNA during Drosophila melanogaster oogenesis

2018 ◽  
Author(s):  
John M. McLaughlin ◽  
Daniel F.Q. Smith ◽  
Irina E. Catrina ◽  
Diana P. Bratu
Keyword(s):  
Drosophila Melanogaster ◽  
Small Rna ◽  
Translational Regulation ◽  
Translational Repression ◽  
Temporal Regulation ◽  
P Bodies ◽  
Maternal Transcripts ◽  
Spatio Temporal ◽  
Mirna Pathway ◽  
Rna Pathways

ABSTRACTEmbryonic axis patterning in Drosophila melanogaster is partly achieved by mRNAs that are maternally localized to the oocyte; the spatio-temporal regulation of these transcripts’ stability and translation is a characteristic feature of oogenesis. While protein regulatory factors are necessary for the translational regulation of some maternal transcripts (e.g. oskar and gurken), small RNA pathways are also known to regulate mRNA stability and translation in eukaryotes. MicroRNAs (miRNAs) are small RNA regulators of gene expression, widely conserved throughout eukaryotic genomes and essential for animal development. The main D. melanogaster anterior determinant, bicoid, is maternally transcribed, but it is not translated until early embryogenesis. We investigated the possibility that its translational repression during oogenesis is mediated by miRNA activity. We found that the bicoid 3’UTR contains a highly conserved, predicted binding site for miR-305. Our studies reveal that miR-305 regulates the translation of a reporter gene containing the bicoid 3’UTR in cell culture, and that miR-305 only partially contributes to bicoid mRNA translational repression during oogenesis. We also found that Processing bodies (P-bodies) in the egg chamber may play a role in stabilizing bicoid and other maternal transcripts. Here, we offer insights into the possible role of P-bodies and the miRNA pathway in the translational repression of bicoid mRNA during oogenesis.

Abstract 1: Role of MicroRNAs in Postranscriptional Regulation of Apolipoprotein B-100 mRNA

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Sahar A Basir ◽  
Tiffany Asante ◽  
Khosrow Adeli
Keyword(s):  
Protein Synthesis ◽  
Mrna Expression ◽  
Apolipoprotein B ◽  
Opposite Effect ◽  
Translational Repression ◽  
Luciferase Reporter ◽  
Hepatoma Cell Line ◽  
P Bodies ◽  
Apob Mrna ◽  
Reporter Assays

Hepatic apolipoprotein B-100 (apoB) synthesis and secretion appears to be regulated largely at the posttranscriptional and posttranslational levels. MicroRNAs (miRNAs) are among posttranscriptional regulators of gene expression that bind to complementary sequences on target messenger RNA (mRNA) transcripts, usually resulting in translational repression or degradation. It is unknown whether specific miRNAs are involved in posttranscriptional regulation of apoB mRNA. We performed bioinformatic analysis, showing that two specific miRNAs with satisfactory E-values level (with levels indicating greater similarity between the input and its match) namely, miR-544 (E-value = 0.91) and miR-1202 (E-value=0.86) have potential to interact with 3’ and 5’ UTR of apoB, respectively. We hypothesized that the interaction of these specific miRNAs (miR-544 and miR-1202) with the 3’ and 5’UTR of apoB mRNA leads to apoB mRNA translational repression and/or activation. Using a human hepatoma cell line model, HepG2, the effects of overexpressed miRNAs and inhibition of endogenous miRNAs on the expression of apoB mRNA and apoB protein synthesis were investigated. We further examined the effect of these miRNAs on apoB mRNA traffic into cytoplasmic P-bodies. Transfection of HepG2 cells with miR-544 led to a significant reduction in apoB mRNA expression and protein synthesis and induced an increase in the co-localization of apoB mRNA into P-bodies. The opposite effect was observed when anti-miR-544 was employed to inhibit the endogenous miR-544. Results from luciferase reporter assays indicated that the effects of miR-544 may be mediated via interaction with the 3’UTR of apoB mRNA. In contrast to miR-544, miR-1202 overexpression induced an increase in apoB mRNA expression and protein synthesis. Similarly, the opposite effect was observed when using anti-miR-1202. Data from luciferase reporter assays showed an increased expression of the reporter gene in constructs carrying 5’UTR of apoB mRNA suggesting that miR-1202 may function via the 5’UTR. In summary, these data demonstrate that specific miRNAs are involved in the regulation of expression and translational control of apoB mRNA in hepatocytes. However, these miRNAs do not appear to mediate insulin regulation.

scholarly journals AtXRN4 Affects the Turnover of Chosen miRNA*s in Arabidopsis

Plants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 362
Author(s):  
Yan Liu ◽  
Wenrui Gao ◽  
Shuangyang Wu ◽  
Lu Lu ◽  
Yaqiu Chen ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Small Rna ◽  
Northern Blot ◽  
Processing Bodies ◽  
Mirna Processing ◽  
P Bodies ◽  
Argonaute 2 ◽  
Qrt Pcr

Small RNA (sRNA) turnover is a key but poorly understood mechanism that determines the homeostasis of sRNAs. Animal XRN genes contribute the degradation of sRNAs, AtXRN2 and AtXRN3 also contribute the pri-miRNA processing and miRNA loop degradation in plants. However, the possible functions of the plant XRN genes in sRNA degradation are far from known. Here, we find that AtXRN4 contributes the turnover of plant sRNAs in Arabidopsis thaliana mainly by sRNA-seq, qRT-PCR and Northern blot. The mutation of AtXRN4 alters the sRNA profile and the accumulation of 21 nt sRNAs was increased. Some miRNA*s levels are significantly increased in xrn4 mutant plants. However, the accumulation of the primary miRNAs (pri-miRNAs) and miRNA precursors (pre-miRNAs) were generally unchanged in xrn4 mutant plants which indicates that AtXRN4 contributes the degradation of some miRNA*s. Moreover, AtXRN4 interacts with Arabidopsis Argonaute 2 (AtAGO2). This interaction takes place in Processing bodies (P-bodies). Taken together, our observations identified the interaction between XRN4 with AtAGO2 and suggested that plant XRN4 also contributes the turnover of sRNAs.

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