scholarly journals The RNA-binding protein PTBP1 promotes ATPase-dependent dissociation of the RNA helicase UPF1 to protect transcripts from nonsense-mediated mRNA decay

2020 ◽  
Vol 295 (33) ◽  
pp. 11613-11625 ◽  
Author(s):  
Sarah E. Fritz ◽  
Soumya Ranganathan ◽  
Clara D. Wang ◽  
J. Robert Hogg
Keyword(s):  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Target Selection ◽  
Rna Helicase ◽  
Nonsense Mediated Decay ◽  
Polypyrimidine Tract Binding Protein ◽  
Regulatory Loop

The sequence-specific RNA-binding proteins PTBP1 (polypyrimidine tract–binding protein 1) and HNRNP L (heterogeneous nuclear ribonucleoprotein L) protect mRNAs from nonsense-mediated decay (NMD) by preventing the UPF1 RNA helicase from associating with potential decay targets. Here, by analyzing in vitro helicase activity, dissociation of UPF1 from purified mRNPs, and transcriptome-wide UPF1 RNA binding, we present the mechanistic basis for inhibition of NMD by PTBP1. Unlike mechanisms of RNA stabilization that depend on direct competition for binding sites among protective RNA-binding proteins and decay factors, PTBP1 promotes displacement of UPF1 already bound to potential substrates. Our results show that PTBP1 directly exploits the tendency of UPF1 to release RNA upon ATP binding and hydrolysis. We further find that UPF1 sensitivity to PTBP1 is coordinated by a regulatory loop in domain 1B of UPF1. We propose that the UPF1 regulatory loop and protective proteins control kinetic proofreading of potential NMD substrates, presenting a new model for RNA helicase regulation and target selection in the NMD pathway.

scholarly journals An Interaction between Two RNA Binding Proteins, Nab2 and Pub1, Links mRNA Processing/Export and mRNA Stability

2007 ◽  
Vol 27 (18) ◽  
pp. 6569-6579 ◽  
Author(s):  
Luciano H. Apponi ◽  
Seth M. Kelly ◽  
Michelle T. Harreman ◽  
Alexander N. Lehner ◽  
Anita H. Corbett ◽  
...  
Keyword(s):  
Mrna Stability ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Tail Length ◽  
Functional Link ◽  
Mrna Binding Protein ◽  
Mrna Binding

ABSTRACT mRNA stability is modulated by elements in the mRNA transcript and their cognate RNA binding proteins. Poly(U) binding protein 1 (Pub1) is a cytoplasmic Saccharomyces cerevisiae mRNA binding protein that stabilizes transcripts containing AU-rich elements (AREs) or stabilizer elements (STEs). In a yeast two-hybrid screen, we identified nuclear poly(A) binding protein 2 (Nab2) as being a Pub1-interacting protein. Nab2 is an essential nucleocytoplasmic shuttling mRNA binding protein that regulates poly(A) tail length and mRNA export. The interaction between Pub1 and Nab2 was confirmed by copurification and in vitro binding assays. The interaction is mediated by the Nab2 zinc finger domain. Analysis of the functional link between these proteins reveals that Nab2, like Pub1, can modulate the stability of specific mRNA transcripts. The half-life of the RPS16B transcript, an ARE-like sequence-containing Pub1 target, is decreased in both nab2-1 and nab2-67 mutants. In contrast, GCN4, an STE-containing Pub1 target, is not affected. Similar results were obtained for other ARE- and STE-containing Pub1 target transcripts. Further analysis reveals that the ARE-like sequence is necessary for Nab2-mediated transcript stabilization. These results suggest that Nab2 functions together with Pub1 to modulate mRNA stability and strengthen a model where nuclear events are coupled to the control of mRNA turnover in the cytoplasm.

scholarly journals The 36-kilodalton embryonic-type cytoplasmic polyadenylation element-binding protein in Xenopus laevis is ElrA, a member of the ELAV family of RNA-binding proteins.

1997 ◽  
Vol 17 (11) ◽  
pp. 6402-6409 ◽  
Author(s):  
L Wu ◽  
P J Good ◽  
J D Richter
Keyword(s):  
Xenopus Laevis ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Dominant Negative ◽  
Cytoplasmic Polyadenylation ◽  
Element Binding Protein

The translational activation of several maternal mRNAs in Xenopus laevis is dependent on cytoplasmic poly(A) elongation. Messages harboring the UUUUUAU-type cytoplasmic polyadenylation element (CPE) in their 3' untranslated regions (UTRs) undergo polyadenylation and translation during oocyte maturation. This CPE is bound by the protein CPEB, which is essential for polyadenylation. mRNAs that have the poly(U)12-27 embryonic-type CPE (eCPE) in their 3' UTRs undergo polyadenylation and translation during the early cleavage and blastula stages. A 36-kDa eCPE-binding protein in oocytes and embryos has been identified by UV cross-linking. We now report that this 36-kDa protein is ElrA, a member of the ELAV family of RNA-binding proteins. The proteins are identical in size, antibody directed against ElrA immunoprecipitates the 36-kDa protein, and the two proteins have the same RNA binding specificity in vitro. C12 and activin receptor mRNAs, both of which contain eCPEs, are detected in immunoprecipitated ElrA-mRNP complexes from eggs and embryos. In addition, this in vivo interaction requires the eCPE. Although a number of experiments failed to define a role for ElrA in cytoplasmic polyadenylation, the expression of a dominant negative ElrA protein in embryos results in an exogastrulation phenotype. The possible functions of ElrA in gastrulation are discussed.

scholarly journals RNA-binding protein altered expression and mislocalization in multiple sclerosis

2019 ◽  
Author(s):  
Katsuhisa Masaki ◽  
Yoshifumi Sonobe ◽  
Ghanashyam Ghadge ◽  
Peter Pytel ◽  
Paula Lépine ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Metabolic Stress ◽  
Nucleocytoplasmic Transport ◽  
Altered Expression ◽  
Polypyrimidine Tract Binding Protein ◽  
Demyelinating Lesions

AbstractObjectiveNuclear depletion and mislocalization of RNA-binding proteins (RBPs) trans-activation response DNA-binding protein of 43 kDa (TDP-43) and fused in sarcoma (FUS) are thought to contribute to the pathogenesis of a number of disorders, including amyotrophic lateral sclerosis (ALS). We recently found that TDP-43 as well as polypyrimidine tract binding protein (PTB) have decreased expression and mislocalization in oligodendrocytes in demyelinated lesions in an experimental mouse model of multiple sclerosis (MS) caused by Theiler’s murine encephalomyelitis virus infection.MethodsThe latter finding prompted us to investigate TDP-43, FUS, and PTB in the demyelinated lesions of MS and in in vitro cultured human brain-derived oligodendrocytes.ResultsWe found: i) mislocalized TDP-43 in oligodendrocytes in active lesions in some MS patients; ii) decreased PTB1 expression in oligodendrocytes in mixed active/inactive demyelinating lesions; iii) decreased nuclear expression of PTB2 in neurons in cortical demyelinating lesions; iv) nuclear depletion of TDP-43 in oligodendrocytes under metabolic stress induced by low glucose/low nutrient conditions compared to optimal culture conditions.ConclusionTDP-43 has been found to have a key role in oligodendrocyte function and viability, while PTB is important in neuronal differentiation, suggesting that altered expression and mislocalization of these RBPs in MS lesions may contribute to the pathogenesis of demyelination and neurodegeneration. Our findings also identify nucleocytoplasmic transport as a target for treatment.

scholarly journals The crystal structure of Staufen1 in complex with a physiological RNA sheds light on substrate selectivity

2018 ◽  
Vol 1 (5) ◽  
pp. e201800187 ◽  
Author(s):  
Daniela Lazzaretti ◽  
Lina Bandholz-Cajamarca ◽  
Christiane Emmerich ◽  
Kristina Schaaf ◽  
Claire Basquin ◽  
...  
Keyword(s):  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Structural Information ◽  
Target Selection ◽  
Mrna Localization ◽  
In Vitro Binding ◽  
Vitro Binding

During mRNA localization, RNA-binding proteins interact with specific structured mRNA localization motifs. Although several such motifs have been identified, we have limited structural information on how these interact with RNA-binding proteins. Staufen proteins bind structured mRNA motifs through dsRNA-binding domains (dsRBD) and are involved in mRNA localization in Drosophila and mammals. We solved the structure of two dsRBDs of human Staufen1 in complex with a physiological dsRNA sequence. We identified interactions between the dsRBDs and the RNA sugar–phosphate backbone and direct contacts of conserved Staufen residues to RNA bases. Mutating residues mediating nonspecific backbone interactions only affected Staufen function in Drosophila when in vitro binding was severely reduced. Conversely, residues involved in base-directed interactions were required in vivo even when they minimally affected in vitro binding. Our work revealed that Staufen can read sequence features in the minor groove of dsRNA and suggests that these influence target selection in vivo.

scholarly journals Protein Factor Requirements of the Apaf-1 Internal Ribosome Entry Segment: Roles of Polypyrimidine Tract Binding Protein and upstream of N-ras

2001 ◽  
Vol 21 (10) ◽  
pp. 3364-3374 ◽  
Author(s):  
Sally A. Mitchell ◽  
Emma C. Brown ◽  
Mark J. Coldwell ◽  
Richard J. Jackson ◽  
Anne E. Willis
Keyword(s):  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Cell Types ◽  
Polypyrimidine Tract ◽  
Internal Ribosome Entry ◽  
Polypyrimidine Tract Binding ◽  
Polypyrimidine Tract Binding Protein ◽  
Different Cell Types

ABSTRACT It has been reported previously that the 5′ untranslated region of the mRNA encoding Apaf-1 (apoptotic protease-activating factor 1) has an internal ribosome entry site (IRES), whose activity varies widely among different cell types. Here it is shown that the Apaf-1 IRES is active in rabbit reticulocyte lysates, provided that the system is supplemented with polypyrimidine tract binding protein (PTB) and upstream of N-ras (unr), two cellular RNA binding proteins previously identified to be required for rhinovirus IRES activity. In UV cross-linking assays and electrophoretic mobility shift assays with individual recombinant proteins, the Apaf-1 IRES binds unr but not PTB; however, PTB binding occurs if unr is present. Over a range of different cell types there is a broad correlation between the activity of the Apaf-1 IRES and their content of PTB and unr. In cell lines deficient in these proteins, overexpression of PTB and unr stimulated Apaf-1 IRES function. This is the first example where an IRES in a cellular mRNA has been shown to be functionally dependent, both in vitro and in vivo, on specific cellular RNA binding proteins. Given the critical role of Apaf-1 in apoptosis, these results have important implications for the control of the apoptotic cascade.

scholarly journals Single-molecule imaging reveals dynamic biphasic partition of RNA-binding proteins in stress granules

2018 ◽  
Vol 217 (4) ◽  
pp. 1303-1318 ◽  
Author(s):  
Benedikt Niewidok ◽  
Maxim Igaev ◽  
Abel Pereira da Graca ◽  
Andre Strassner ◽  
Christine Lenzen ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Single Molecule ◽  
Mammalian Cells ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Liquid Droplet ◽  
Binding Protein ◽  
Stress Granules

Stress granules (SGs) are cytosolic, nonmembranous RNA–protein complexes. In vitro experiments suggested that they are formed by liquid–liquid phase separation; however, their properties in mammalian cells remain unclear. We analyzed the distribution and dynamics of two paradigmatic RNA-binding proteins (RBPs), Ras GTPase-activating protein SH3-domain–binding protein (G3BP1) and insulin-like growth factor II mRNA-binding protein 1 (IMP1), with single-molecule resolution in living neuronal cells. Both RBPs exhibited different exchange kinetics between SGs. Within SGs, single-molecule localization microscopy revealed distributed hotspots of immobilized G3BP1 and IMP1 that reflect the presence of relatively immobile nanometer-sized nanocores. We demonstrate alternating binding in nanocores and anomalous diffusion in the liquid phase with similar characteristics for both RBPs. Reduction of low-complexity regions in G3BP1 resulted in less detectable mobile molecules in the liquid phase without change in binding in nanocores. The data provide direct support for liquid droplet behavior of SGs in living cells and reveal transient binding of RBPs in nanocores. Our study uncovers a surprising disconnect between SG partitioning and internal diffusion and interactions of RBPs.

scholarly journals RNA-binding protein altered expression and mislocalization in MS

2020 ◽  
Vol 7 (3) ◽  
pp. e704 ◽  
Author(s):  
Katsuhisa Masaki ◽  
Yoshifumi Sonobe ◽  
Ghanashyam Ghadge ◽  
Peter Pytel ◽  
Paula Lépine ◽  
...  
Keyword(s):  
Human Brain ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Metabolic Stress ◽  
Nucleocytoplasmic Transport ◽  
Altered Expression ◽  
Polypyrimidine Tract Binding Protein ◽  
Demyelinating Lesions

ObjectiveTo determine whether there are nuclear depletion and cellular mislocalization of RNA-binding proteins (RBPs) transactivation response DNA-binding protein of 43 kDa (TDP-43), fused in sarcoma (FUS), and polypyrimidine tract–binding protein (PTB) in MS, as is the case in amyotrophic lateral sclerosis (ALS) and oligodendrocytes infected with Theiler murine encephalomyelitis virus (TMEV), we examined MS lesions and in vitro cultured primary human brain–derived oligodendrocytes.MethodsNuclear depletion and mislocalization of TDP-43, FUS, and PTB are thought to contribute to the pathogenesis of ALS and TMEV demyelination. The latter findings prompted us to investigate these RBPs in the demyelinated lesions of MS and in in vitro cultured human brain–derived oligodendrocytes under metabolic stress conditions.ResultsWe found (1) mislocalized TDP-43 in oligodendrocytes in active lesions in some patients with MS; (2) decreased PTB1 expression in oligodendrocytes in mixed active/inactive demyelinating lesions; (3) decreased nuclear expression of PTB2 in neurons in cortical demyelinating lesions; and (4) nuclear depletion of TDP-43 in oligodendrocytes under metabolic stress induced by low glucose/low nutrient conditions compared with optimal culture conditions.ConclusionTDP-43 has been found to have a key role in oligodendrocyte function and viability, whereas PTB is important in neuronal differentiation, suggesting that altered expression and mislocalization of these RBPs in MS lesions may contribute to the pathogenesis of demyelination and neurodegeneration. Our findings also identify nucleocytoplasmic transport as a target for treatment.

scholarly journals Translation of Polioviral mRNA Is Inhibited by Cleavage of Polypyrimidine Tract-Binding Proteins Executed by Polioviral 3Cpro

2002 ◽  
Vol 76 (5) ◽  
pp. 2529-2542 ◽  
Author(s):  
Sung Hoon Back ◽  
Yoon Ki Kim ◽  
Woo Jae Kim ◽  
Sungchan Cho ◽  
Hoe Rang Oh ◽  
...  
Keyword(s):  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Internal Ribosomal Entry Site ◽  
Polypyrimidine Tract ◽  
Entry Site ◽  
Polypyrimidine Tract Binding ◽  
Polypyrimidine Tract Binding Protein ◽  
Target Sites

ABSTRACT The translation of polioviral mRNA occurs through an internal ribosomal entry site (IRES). Several RNA-binding proteins, such as polypyrimidine tract-binding protein (PTB) and poly(rC)-binding protein (PCBP), are required for the poliovirus IRES-dependent translation. Here we report that a poliovirus protein, 3Cpro (and/or 3CDpro), cleaves PTB isoforms (PTB1, PTB2, and PTB4). Three 3Cpro target sites (one major target site and two minor target sites) exist in PTBs. PTB fragments generated by poliovirus infection are redistributed to the cytoplasm from the nucleus, where most of the intact PTBs are localized. Moreover, these PTB fragments inhibit polioviral IRES-dependent translation in a cell-based assay system. We speculate that the proteolytic cleavage of PTBs may contribute to the molecular switching from translation to replication of polioviral RNA.

scholarly journals The Interplay of RNA Binding Proteins, Oxidative Stress and Mitochondrial Dysfunction in ALS

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 552
Author(s):  
Jasmine Harley ◽  
Benjamin E. Clarke ◽  
Rickie Patani
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Mitochondrial Dysfunction ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Therapeutic Strategies ◽  
Lateral Sclerosis

RNA binding proteins fulfil a wide number of roles in gene expression. Multiple mechanisms of RNA binding protein dysregulation have been implicated in the pathomechanisms of several neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Oxidative stress and mitochondrial dysfunction also play important roles in these diseases. In this review, we highlight the mechanistic interplay between RNA binding protein dysregulation, oxidative stress and mitochondrial dysfunction in ALS. We also discuss different potential therapeutic strategies targeting these pathways.

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