scholarly journals Identification of novel nesprin-1 binding partners and cytoplasmic matrin-3 in processing bodies

2016 ◽  
Vol 27 (24) ◽  
pp. 3894-3902 ◽  
Author(s):  
Dipen Rajgor ◽  
Jonathan G. Hanley ◽  
Catherine M. Shanahan
Keyword(s):  
Mass Spectrometry ◽  
Mrna Processing ◽  
Scaffold Proteins ◽  
Processing Bodies ◽  
Spectrin Repeat ◽  
Rna Granules ◽  
Matrin 3 ◽  
Binding Partners ◽  
Cytoplasmic Rna ◽  
Stressed Cells

Nesprins are highly conserved spectrin repeat–containing scaffold proteins predominantly known to function at the nuclear envelope (NE). However, nesprin isoforms are emerging with localizations and scaffolding functions at sites away from the NE, suggesting their functions are more diverse than originally thought. In this study, we combined nesprin-1 coimmunoprecipitations with mass spectrometry to identify novel nesprin-1 binding partners for isoforms that localize to subcellular compartments beyond the NE. We show that one of these interactors, matrin-3 (matr3), localizes to mRNA processing bodies (PBs), where we have previously shown a nesprin-1 isoform to localize. Furthermore, we show that Matr3 is part of PB mRNP complexes, is a regulator of miRNA-mediated gene silencing, and possibly shuttles to stress granules in stressed cells. More importantly, we identify a new C-terminally truncated Matr3 isoform that is likely to be involved in these functions and PB localization. This study highlights several novel nesprin-1 binding partners and a new function and localization for Matr3 in cytoplasmic RNA granules.

scholarly journals Edc3p and a glutamine/asparagine-rich domain of Lsm4p function in processing body assembly in Saccharomyces cerevisiae

2007 ◽  
Vol 179 (3) ◽  
pp. 437-449 ◽  
Author(s):  
Carolyn J. Decker ◽  
Daniela Teixeira ◽  
Roy Parker
Keyword(s):  
Protein Interactions ◽  
Messenger Rna ◽  
Mrna Decay ◽  
Processing Bodies ◽  
P Bodies ◽  
Rna Granules ◽  
Rich Domain ◽  
Cytoplasmic Rna ◽  
Processing Body ◽  
The Individual

Processing bodies (P-bodies) are cytoplasmic RNA granules that contain translationally repressed messenger ribonucleoproteins (mRNPs) and messenger RNA (mRNA) decay factors. The physical interactions that form the individual mRNPs within P-bodies and how those mRNPs assemble into larger P-bodies are unresolved. We identify direct protein interactions that could contribute to the formation of an mRNP complex that consists of core P-body components. Additionally, we demonstrate that the formation of P-bodies that are visible by light microscopy occurs either through Edc3p, which acts as a scaffold and cross-bridging protein, or via the “prionlike” domain in Lsm4p. Analysis of cells defective in P-body formation indicates that the concentration of translationally repressed mRNPs and decay factors into microscopically visible P-bodies is not necessary for basal control of translation repression and mRNA decay. These results suggest a stepwise model for P-body assembly with the initial formation of a core mRNA–protein complex that then aggregates through multiple specific mechanisms.

scholarly journals Hepatitis C Virus Exploitation of Processing Bodies

2016 ◽  
Vol 90 (10) ◽  
pp. 4860-4863 ◽  
Author(s):  
Jason M. Biegel ◽  
Cara T. Pager
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Defense Mechanisms ◽  
Viral Proteins ◽  
Processing Bodies ◽  
Viral Genomes ◽  
Rna Granules ◽  
Cytoplasmic Rna ◽  
Cellular Machinery ◽  
Positive Strand Rna

During infection, positive-strand RNA viruses subvert cellular machinery involved in RNA metabolism to translate viral proteins and replicate viral genomes to avoid or disable the host defense mechanisms. Cytoplasmic RNA granules modulate the stabilities of cellular and viral RNAs. Understanding how hepatitis C virus and other flaviviruses interact with the host machinery required for protein synthesis, localization, and degradation of mRNAs is important for elucidating how these processes occur in both virus-infected and uninfected cells.

scholarly journals RNA granules

2006 ◽  
Vol 172 (6) ◽  
pp. 803-808 ◽  
Author(s):  
Paul Anderson ◽  
Nancy Kedersha
Keyword(s):  
Messenger Rna ◽  
Posttranscriptional Regulation ◽  
Spatial Organization ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Regulation Of Gene Expression ◽  
Processing Bodies ◽  
Rna Granules ◽  
Cytoplasmic Rna ◽  
Messenger Rna Translation

Cytoplasmic RNA granules in germ cells (polar and germinal granules), somatic cells (stress granules and processing bodies), and neurons (neuronal granules) have emerged as important players in the posttranscriptional regulation of gene expression. RNA granules contain various ribosomal subunits, translation factors, decay enzymes, helicases, scaffold proteins, and RNA-binding proteins, and they control the localization, stability, and translation of their RNA cargo. We review the relationship between different classes of these granules and discuss how spatial organization regulates messenger RNA translation/decay.

scholarly journals Oxidized RNA Bodies compartmentalize translation quality control in Saccharomyces cerevisiae

2020 ◽  
Author(s):  
James S. Dhaliwal ◽  
Cristina Panozzo ◽  
Lionel Benard ◽  
William Zerges
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quality Control ◽  
Chain Complex ◽  
Processing Bodies ◽  
Rna Granules ◽  
Translation Quality ◽  
Control Factors ◽  
Cytoplasmic Rna ◽  
Nascent Chain

ABSTRACTCytoplasmic RNA granules compartmentalize phases of the translation cycle. We previously reported on the localization of oxidized RNA in human cells to cytoplasmic foci called oxidized RNA bodies (ORBs). Oxidized mRNAs are substrates of translation quality control, wherein defective mRNAs and nascent polypeptides are released from stalled ribosomes and targeted for degradation. Therefore, we asked whether ORBs compartmentalize translation quality control. Here, we identify ORBs in Saccharomyces cerevisiae and characterize them using fluorescence microscopy and proteomics. ORBs are RNA granules that are distinct from processing bodies and stress granules. Several lines of evidence support a role of ORBs in the compartmentalization of central steps in the translation quality control pathways No-Go mRNA decay and ribosome quality control. Active translation is required by both translation quality control and ORBs. ORBs contain two substrates of translation quality control: oxidized RNA and a stalled mRNA-ribosome-nascent chain complex. Translation quality control factors localize to ORBs. Translation quality control mutants have altered ORB number per cell, size, or both. Therefore, ORBs are an intracellular hub of translational quality control.

scholarly journals How stressed cells triage mRNAs

2015 ◽  
Vol 211 (5) ◽  
pp. 940-940
Author(s):  
Caitlin Sedwick
Keyword(s):  
Dynamic Interactions ◽  
Rna Granules ◽  
Cytoplasmic Rna ◽  
Stressed Cells

In 2005, Kedersha et al. demonstrated the dynamic interactions between cytoplasmic RNA granules.

scholarly journals RNA helicase DDX6 in P-bodies is essential for the assembly of stress granules

2021 ◽  
Author(s):  
Vladimir Majerciak ◽  
Tongqing Zhou ◽  
Zhi-Ming Zheng
Keyword(s):  
Rna Processing ◽  
Stress Granules ◽  
The Other ◽  
Helicase Activity ◽  
Dual Roles ◽  
Processing Bodies ◽  
P Bodies ◽  
Rna Granules ◽  
Cytoplasmic Rna ◽  
Conceptual Advance

Two prominent cytoplasmic RNA granules, ubiquitous RNA-processing bodies (PB) and inducible stress granules (SG), regulate storage of translationally arrested mRNAs and are intimately related. In this study, we found the dependence of SG formation on PB in the cells under arsenite (ARS) stress, but not the other way around. GW182, 4E-T and DDX6 essential for PB formation differentially affect SG formation in the cells under ARS stress, with DDX6 being the most prominent. The cells with DDX6 deficiency display irregular shape of SG which could be rescued by ectopic wt DDX6, but not its helicase mutant E247A DDX6, which induces SG in the cells without stress, indicating that DDX6 helicase activity is essential for PB, but suppressive for SG. DDX6's dual roles are independent of DDX6 interactors EDC3, CNOT1, and PAT1B. This study provides a conceptual advance of how DDX6 involves in the biogenesis of PB and SG.

scholarly journals Mammalian microtubule P-body dynamics are mediated by nesprin-1

2014 ◽  
Vol 205 (4) ◽  
pp. 457-475 ◽  
Author(s):  
Dipen Rajgor ◽  
Jason A. Mellad ◽  
Daniel Soong ◽  
Jerome B. Rattner ◽  
Marvin J. Fritzler ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Nuclear Envelope ◽  
Sodium Arsenite ◽  
Sr Proteins ◽  
Dominant Negative ◽  
Dependent Manner ◽  
Processing Bodies ◽  
Spectrin Repeat ◽  
Microtubule Attachment ◽  
Body Dynamics

Nesprins are a multi-isomeric family of spectrin-repeat (SR) proteins, predominantly known as nuclear envelope scaffolds. However, isoforms that function beyond the nuclear envelope remain poorly examined. Here, we characterize p50Nesp1, a 50-kD isoform that localizes to processing bodies (PBs), where it acts as a microtubule-associated protein capable of linking mRNP complexes to microtubules. Overexpression of dominant-negative p50Nesp1 caused Rck/p54, but not GW182, displacement from microtubules, resulting in reduced PB movement and cross talk with stress granules (SGs). These cells disassembled canonical SGs induced by sodium arsenite, but not those induced by hydrogen peroxide, leading to cell death and revealing PB–microtubule attachment is required for hydrogen peroxide-induced SG anti-apoptotic functions. Furthermore, p50Nesp1 was required for miRNA-mediated silencing and interacted with core miRISC silencers Ago2 and Rck/p54 in an RNA-dependent manner and with GW182 in a microtubule-dependent manner. These data identify p50Nesp1 as a multi-functional PB component and microtubule scaffold necessary for RNA granule dynamics and provides evidence for PB and SG micro-heterogeneity.

scholarly journals The histone chaperone Spt6 is required for normal recruitment of the capping enzyme Abd1 to transcribed regions

2021 ◽  
Author(s):  
Rajaraman Gopalakrishnan ◽  
Fred Winston
Keyword(s):  
Mass Spectrometry ◽  
Rna Polymerase Ii ◽  
Transcription Elongation ◽  
Histone Chaperone ◽  
Mrna Processing ◽  
Wild Type ◽  
Elongation Complex ◽  
Protein Levels ◽  
Genome Wide ◽  
Capping Enzyme

The histone chaperone Spt6 is involved in promoting elongation of RNA polymerase II (RNAPII), maintaining chromatin structure, regulating co-transcriptional histone modifications, and controlling mRNA processing. These diverse functions of Spt6 are partly mediated through its interactions with RNAPII and other factors in the transcription elongation complex. In this study, we used mass spectrometry to characterize the differences in RNAPII interacting factors between wild-type cells and those depleted for Spt6, leading to the identification of proteins that depend on Spt6 for their interaction with RNAPII. The altered association of some of these factors could be attributed to changes in steady-state protein levels. However, Abd1, the mRNA cap methyltransferase, had decreased association with RNAPII after Spt6 depletion despite unchanged Abd1 protein levels, showing a requirement for Spt6 in mediating the Abd1-RNAPII interaction. Genome-wide studies showed that Spt6 is required for maintaining the level of Abd1 over transcribed regions, as well as the level of Spt5, another protein known to recruit Abd1 to chromatin. Abd1 levels were particularly decreased at the 5 ends of genes after Spt6 depletion, suggesting a greater need for Spt6 in Abd1 recruitment over these regions. Together, our results show that Spt6 is important in regulating the composition of the transcription elongation complex and reveal a previously unknown function for Spt6 in the recruitment of Abd1.

scholarly journals Mapping Interactome Networks of FOSL1 and FOSL2 in Human Th17 Cells

2021 ◽  
Author(s):  
Ankitha Shetty ◽  
Santosh D. Bhosale ◽  
Subhash Kumar Tripathi ◽  
Tanja Buchacher ◽  
Rahul Biradar ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Cell Differentiation ◽  
Th17 Cell ◽  
Th17 Cells ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Affinity Purification ◽  
Mass Spectrometry Analysis ◽  
Binding Partners ◽  
Th17 Cell Differentiation

Dysregulated function of Th17 cells has implications in immunodeficiencies and autoimmune disorders. Th17 cell-differentiation is orchestrated by a complex network of transcription factors, including several members of the activator protein (AP-1) family. Among these, FOSL1 and FOSL2 influence the effector responses of Th17 cells. However, the molecular mechanisms underlying their functions are unclear, owing to the poorly characterized protein interaction networks of these factors. Here, we establish the first interactomes of FOSL1 and FOSL2 in human Th17 cells, using affinity purification–mass spectrometry analysis. In addition to the known JUN proteins, we identified several novel binding partners of FOSL1 and FOSL2. Gene ontology analysis found a major fraction of these interactors to be associated with RNA binding activity, which suggests new mechanistic links. Intriguingly, 29 proteins were found to share interactions with FOSL1 and FOSL2, and these included key regulators of Th17-fate. We further validated the binding partners identified in this study by using parallel reaction monitoring targeted mass spectrometry and other methods. Our study provides key insights into the interaction-based signaling mechanisms of FOSL1 and FOSL2 that potentially govern Th17 cell-differentiation and associated pathologies.

scholarly journals Stress induces the assembly of RNA granules in the chloroplast of Chlamydomonas reinhardtii

2008 ◽  
Vol 182 (4) ◽  
pp. 641-646 ◽  
Author(s):  
James Uniacke ◽  
William Zerges
Keyword(s):  
Oxidative Stress ◽  
Chlamydomonas Reinhardtii ◽  
Large Subunit ◽  
Ribosomal Subunit ◽  
Stress Granules ◽  
Mrna Localization ◽  
Messenger Rnas ◽  
Rna Granules ◽  
Cytoplasmic Rna ◽  
Ribulosebisphosphate Carboxylase

Eukaryotic cells under stress repress translation and localize these messenger RNAs (mRNAs) to cytoplasmic RNA granules. We show that specific stress stimuli induce the assembly of RNA granules in an organelle with bacterial ancestry, the chloroplast of Chlamydomonas reinhardtii. These chloroplast stress granules (cpSGs) form during oxidative stress and disassemble during recovery from stress. Like mammalian stress granules, cpSGs contain poly(A)-binding protein and the small, but not the large, ribosomal subunit. In addition, mRNAs are in continuous flux between polysomes and cpSGs during stress. Localization of cpSGs within the pyrenoid reveals that this chloroplast compartment functions in this stress response. The large subunit of ribulosebisphosphate carboxylase/oxygenase also assembles into cpSGs and is known to bind mRNAs during oxidative stress, raising the possibility that it plays a role in cpSG assembly. This discovery within such an organelle suggests that mRNA localization to granules during stress is a more general phenomenon than currently realized.

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