scholarly journals Insights into the Biology of IRES Elements through Riboproteomic Approaches

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Almudena Pacheco ◽  
Encarnacion Martinez-Salas
Keyword(s):  
Gene Expression ◽  
Translation Initiation ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Entry Site ◽  
Rna Sequences ◽  
Initiation Mechanism ◽  
Internal Ribosome Entry ◽  
Control Of Gene Expression ◽  
Eukaryotic Mrnas

Translation initiation is a highly regulated process that exerts a strong influence on the posttranscriptional control of gene expression. Two alternative mechanisms govern translation initiation in eukaryotic mRNAs, the cap-dependent initiation mechanism operating in most mRNAs, and the internal ribosome entry site (IRES)-dependent mechanism, first discovered in picornaviruses. IRES elements are highly structured RNA sequences that, in most instances, require specific proteins for recruitment of the translation machinery. Some of these proteins are eukaryotic initiation factors. In addition, RNA-binding proteins (RBPs) play a key role in internal initiation control. RBPs are pivotal regulators of gene expression in response to numerous stresses, including virus infection. This review discusses recent advances on riboproteomic approaches to identify IRES transacting factors (ITAFs) and the relationship between RNA-protein interaction and IRES activity, highlighting the most relevant features on picornavirus and hepatitis C virus IRESs.

scholarly journals Compendium of Methods to Uncover RNA-Protein Interactions In Vivo

2021 ◽  
Vol 4 (1) ◽  
pp. 22
Author(s):  
Mrinmoyee Majumder ◽  
Viswanathan Palanisamy
Keyword(s):  
Gene Expression ◽  
Protein Interactions ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Expression Patterns ◽  
Control Of Gene Expression ◽  
Regulatory Pathways ◽  
Advantages And Disadvantages ◽  
Protein Nucleic Acid

Control of gene expression is critical in shaping the pro-and eukaryotic organisms’ genotype and phenotype. The gene expression regulatory pathways solely rely on protein–protein and protein–nucleic acid interactions, which determine the fate of the nucleic acids. RNA–protein interactions play a significant role in co- and post-transcriptional regulation to control gene expression. RNA-binding proteins (RBPs) are a diverse group of macromolecules that bind to RNA and play an essential role in RNA biology by regulating pre-mRNA processing, maturation, nuclear transport, stability, and translation. Hence, the studies aimed at investigating RNA–protein interactions are essential to advance our knowledge in gene expression patterns associated with health and disease. Here we discuss the long-established and current technologies that are widely used to study RNA–protein interactions in vivo. We also present the advantages and disadvantages of each method discussed in the review.

238 RNA BINDING PROTEIN EXPRESSION IN CULTURED EARLY BOVINE EMBRYOS

2010 ◽  
Vol 22 (1) ◽  
pp. 277
Author(s):  
L. A. Favetta ◽  
E. Van de Laar ◽  
W. A. King ◽  
J. LaMarre
Keyword(s):  
Gene Expression ◽  
Protein Expression ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Bovine Embryo ◽  
Rt Pcr ◽  
Control Of Gene Expression ◽  
Morula Stage ◽  
Bovine Oocytes

The control of gene expression in the early embryo requires a highly regulated turnover of specific mRNA, particularly those of maternal origin, as the embryo becomes transcriptionally autonomous. In cattle, the period during which maternal transcripts persist can last 72 to 96 h or longer, suggesting a dynamic, regulated interplay between factors that protect transcripts before this point and those that subsequently facilitate decay. Some decay pathways for specific embryonic transcripts are now known, but many are not. In somatic cells, mRNA decay is often mediated by interactions between defined sequence elements (ARE) in the 3′ untranslated region of important target genes and specific RNA-binding proteins (AUBP) that promote or inhibit decay of the associated transcript. These have not been extensively characterized in embryos. We hypothesized that changes in the pattern of expression of one or several AUBP in the developing bovine embryo would support a role for these proteins in mRNA turnover and the control of gene expression. We, therefore, evaluated the expression of different AUBP (HuR, AUF1, TTP) in bovine oocytes and early embryos in vitro. Bovine oocytes obtained at slaughter were matured, fertilized, and cultured using standard protocols. Oocytes and embryos from different stages were either placed in Trizol for subsequent RNA isolation and RT-PCR analysis or fixed in 4% paraformaldehyde and subsequently processed for immunohistochemical detection of AUBP. Analysis by RT-PCR revealed that AUF1, an mRNA destabilizing protein, was expressed at all stages examined (immature oocyte, mature oocyte, 2 to 4 cells, 8 to 16 cells, morulae, and blastocyst) except in morulae. Another mRNA destabilizing protein, TTP, was expressed at the morula stage only. An mRNA stabilizing factor, HuR, was expressed at all stages except the morula. Immunohistochemical analysis revealed that the pattern of protein expression for AUF1 and TTP essentially mirrored that observed at the RNA level as detected by RT-PCR. Together, these results show that AUBP expression in the early bovine embryo is dynamic, with RNA-binding proteins present at all times during development and changes in expression evident at the morula stage. This suggests that modification of presynthesized (i.e. maternal) AUBP is likely to control mRNA decay during the maternal to embryonic transition (8-cell stage) and that the expression of TTP at the morula stage might mark the onset of embryonic control of mRNA stability. Research was supported by NSERC, OMAFRA, and the Canada Research Chairs Program.

scholarly journals Efficient Translation Initiation Directed by the 900-Nucleotide-Long and GC-Rich 5′ Untranslated Region of the Human Retrotransposon LINE-1 mRNA Is Strictly Cap Dependent Rather than Internal Ribosome Entry Site Mediated

2007 ◽  
Vol 27 (13) ◽  
pp. 4685-4697 ◽  
Author(s):  
Sergey E. Dmitriev ◽  
Dmitri E. Andreev ◽  
Ilya M. Terenin ◽  
Ivan A. Olovnikov ◽  
Vladimir S. Prassolov ◽  
...  
Keyword(s):  
Translation Initiation ◽  
Internal Ribosome Entry Site ◽  
Untranslated Region ◽  
High Efficiency ◽  
Rna Binding ◽  
Cultured Cells ◽  
Entry Site ◽  
Internal Ribosome Entry ◽  
Cellular Mrnas ◽  
Internal Initiation

ABSTRACT Retrotransposon L1 is a mobile genetic element of the LINE family that is extremely widespread in the mammalian genome. It encodes a dicistronic mRNA, which is exceptionally rare among eukaryotic cellular mRNAs. The extremely long and GC-rich L1 5′ untranslated region (5′UTR) directs synthesis of numerous copies of RNA-binding protein ORF1p per mRNA. One could suggest that the 5′UTR of L1 mRNA contained a powerful internal ribosome entry site (IRES) element. Using transfection of cultured cells with the polyadenylated monocistronic (L1 5′UTR-Fluc) or bicistronic (Rluc-L1 5′UTR-Fluc) RNA constructs, capped or uncapped, it has been firmly established that the 5′UTR of L1 does not contain an IRES. Uncapping reduces the initiation activity of the L1 5′UTR to that of background. Moreover, the translation is inhibited by upstream AUG codons in the 5′UTR. Nevertheless, this cap-dependent initiation activity of the L1 5′UTR was unexpectedly high and resembles that of the beta-actin 5′UTR (84 nucleotides long). Strikingly, the deletion of up to 80% of the nucleotide sequence of the L1 5′UTR, with most of its stem loops, does not significantly change its translation initiation efficiency. These data can modify current ideas on mechanisms used by 40S ribosomal subunits to cope with complex 5′UTRs and call into question the conception that every long GC-rich 5′UTR working with a high efficiency has to contain an IRES. Our data also demonstrate that the ORF2 translation initiation is not directed by internal initiation, either. It is very inefficient and presumably based on a reinitiation event.

scholarly journals Cip1 and Cip2 Are Novel RNA-Recognition-Motif Proteins That Counteract Csx1 Function during Oxidative Stress

2006 ◽  
Vol 17 (3) ◽  
pp. 1176-1183 ◽  
Author(s):  
Victoria Martín ◽  
Miguel A. Rodríguez-Gabriel ◽  
W. Hayes McDonald ◽  
Stephen Watt ◽  
John R. Yates ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Stress Response ◽  
Protein Identification ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Bzip Transcription Factor ◽  
Rna Recognition Motif ◽  
Rna Recognition ◽  
Control Of Gene Expression

Eukaryotic cells reprogram their global patterns of gene expression in response to stress. Recent studies in Schizosaccharomyces pombe showed that the RNA-binding protein Csx1 plays a central role in controlling gene expression during oxidative stress. It does so by stabilizing atf1+ mRNA, which encodes a subunit of a bZIP transcription factor required for gene expression during oxidative stress. Here, we describe two related proteins, Cip1 and Cip2, that were identified by multidimensional protein identification technology (MudPIT) as proteins that coprecipitate with Csx1. Cip1 and Cip2 are cytoplasmic proteins that have RNA recognition motifs (RRMs). Neither protein is essential for viability, but a cip1Δ cip2Δ strain grows poorly and has altered cellular morphology. Genetic epistasis studies and whole genome expression profiling show that Cip1 and Cip2 exert posttranscriptional control of gene expression in a manner that is counteracted by Csx1. Notably, the sensitivity of csx1Δ cells to oxidative stress and their inability to induce expression of Atf1-dependent genes are partially rescued by cip1Δ and cip2Δ mutations. This study emphasizes the importance of a modulated mRNA stability in the eukaryotic stress response pathways and adds new information to the role of RNA-binding proteins in the oxidative stress response.

The hepatitis C virus internal ribosome-entry site: a new target for antiviral research

2002 ◽  
Vol 30 (2) ◽  
pp. 140-145 ◽  
Author(s):  
J. Gallego ◽  
G. Varani
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Translation Initiation ◽  
Internal Ribosome Entry Site ◽  
Ribosomal Subunit ◽  
Initiation Factor ◽  
Entry Site ◽  
Viral Protein Synthesis ◽  
Initiation Mechanism ◽  
Internal Ribosome Entry

The hepatitis C virus (HCV) is the main causative agent of non-A, non-B hepatitis in humans and a major cause of mortality and morbidity in the world. Currently there is no effective treatment available for the infection caused by this virus, whose replication depends on an unusual translation-initiation mechanism. The viral RNA contains an internal ribosome-entry site (IRES) that is recognized specifically by the small ribosomal subunit and by eukaryotic initiation factor 3, and these interactions allow cap (7-methylguanine nucleotide)-independent initiation of viral protein synthesis. In this article, we review the structure and mechanism of translation initiation of the HCV IRES, and its potential as a target for novel antivirals.

scholarly journals Cancer-associated mRNAs regulated by the Helix-Loop-Helix motif of human EIF3A

2018 ◽  
Author(s):  
Marina Volegova ◽  
Jamie H.D. Cate
Keyword(s):  
Translation Initiation ◽  
Rna Binding ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Binding Motif ◽  
Entry Site ◽  
Internal Ribosome Entry ◽  
Helix Loop Helix ◽  
Small Set

AbstractImproper regulation of translation initiation, a vital check-point of protein synthesis in the cell, has been linked to a number of cancers. Overexpression of protein subunits of eukaryotic translation initiation factor 3 (eIF3) has been associated with increased translation of mRNAs involved in cell proliferation. In addition to playing a major role in general translation initiation by serving as a scaffold for the assembly of translation initiation complexes, eIF3 regulates translation of specific cellular mRNAs and viral RNAs. Mutations in the N-terminal Helix-Loop-Helix (HLH) RNA-binding motif of the EIF3A subunit in eIF3 interfere with Hepatitis C Virus Internal Ribosome Entry Site (IRES) mediated translation initiationin vitro. Here we show that the EIF3A HLH motif controls translation of a small set of cellular transcripts enriched in oncogenic mRNAs, includingMYC. We also demonstrate that the HLH motif of EIF3A acts specifically on the 5’-UTR ofMYCmRNA and modulates the function of EIF4A1 on select transcripts during translation initiation. In Ramos lymphoma cell lines, which are dependent on MYC overexpression, mutations in the HLH motif greatly reduce MYC expression, impede proliferation and sensitize cells to anti-cancer compounds. These results reveal the potential of the EIF3A HLH motif in eIF3 as a promising chemotherapeutic target.SummaryThe Helix Loop Helix motif of EIF3A controls translation of a small set of oncogenic cellular transcripts, includingMYC, and modulates the function of translation initiation factor EIF4A1 during translation initiation on select mRNAs.

scholarly journals RsmV a small non-coding regulatory RNA in Pseudomonas aeruginosa that sequesters RsmA and RsmF from target mRNAs

2018 ◽  
Author(s):  
Kayley H. Janssen ◽  
Manisha R. Diaz ◽  
Cindy J. Gode ◽  
Matthew C. Wolfgang ◽  
Timothy L. Yahr
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Binding Sites ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Secretion System ◽  
Transcriptional Level ◽  
Type Vi Secretion System ◽  
Control Of Gene Expression ◽  
Target Mrnas

ABSTRACTThe Gram-negative opportunistic pathogen Pseudomonas aeruginosa has distinct genetic programs that favor either acute or chronic virulence gene expression. Acute virulence is associated with twitching and swimming motility, expression of a type III secretion system (T3SS), and the absence of alginate, Psl, or Pel polysaccharide production. Traits associated with chronic infection include growth as a biofilm, reduced motility, and expression of a type VI secretion system (T6SS). The Rsm post-transcriptional regulatory system plays an important role in the inverse control of phenotypes associated with acute and chronic virulence. RsmA and RsmF are RNA-binding proteins that interact with target mRNAs to control gene expression at the post-transcriptional level. Previous work found that RsmA activity is controlled by at least three small, non-coding regulatory RNAs (RsmW, RsmY, and RsmZ). In this study, we took an in-silico approach to identify additional sRNAs that might function in the sequestration of RsmA and/or RsmF and identified RsmV, a 192 nt transcript with four predicted RsmA/RsmF consensus binding sites. RsmV is capable of sequestering RsmA and RsmF in vivo to activate translation of tssA1, a component of the T6SS, and to inhibit T3SS gene expression. Each of the predicted RsmA/RsmF consensus binding sites contribute to RsmV activity. Electrophoretic mobility shifts assays show that RsmF binds RsmV with >10-fold higher affinity than RsmY and RsmZ. Gene expression studies revealed that the temporal expression pattern of RsmV differs from RsmW, RsmY, and RsmZ. These findings suggest that each sRNA may play distinct roles in controlling RsmA and RsmF activity.IMPORTANCEThe role of RsmF in post-transcriptional control of gene expression remains enigmatic. While numerous rsmA-dependent phenotypes are more pronounced in an rsmAF double mutant, deletion of rsmF alone has only modest effects. Understanding mechanisms that control RsmF activity will provide insight into additional roles for RsmF. In the current study we identify RsmV as an sRNA that controls RsmA and RsmF activity, and show that RsmV, RsmW, RsmY, and RsmZ are differentially expressed during growth.

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