Interaction of polypyrimidine tract binding protein with the encephalomyocarditis virus mRNA internal ribosomal entry site

Biochemistry ◽  
1993 ◽  
Vol 32 (32) ◽  
pp. 8268-8275 ◽  
Author(s):  
Gary W. Witherell ◽  
Anna Gil ◽  
Eckard Wimmer
Keyword(s):  
Binding Protein ◽  
Internal Ribosomal Entry Site ◽  
Encephalomyocarditis Virus ◽  
Polypyrimidine Tract ◽  
Entry Site ◽  
Polypyrimidine Tract Binding ◽  
Polypyrimidine Tract Binding Protein ◽  
Ribosomal Entry

scholarly journals Polypyrimidine Tract-Binding Protein Enhances the Internal Ribosomal Entry Site-Dependent Translation of p27Kip1 mRNA and Modulates Transition from G1 to S Phase

2005 ◽  
Vol 25 (4) ◽  
pp. 1283-1297 ◽  
Author(s):  
Sungchan Cho ◽  
Jong Heon Kim ◽  
Sung Hoon Back ◽  
Sung Key Jang
Keyword(s):  
Cell Cycle ◽  
Binding Protein ◽  
Internal Ribosomal Entry Site ◽  
In Vitro Translation ◽  
Polypyrimidine Tract ◽  
Entry Site ◽  
Hl60 Cells ◽  
Polypyrimidine Tract Binding ◽  
Polypyrimidine Tract Binding Protein ◽  
Ribosomal Entry

ABSTRACT The p27Kip1 protein plays a critical role in the regulation of cell proliferation through the inhibition of cyclin-dependent kinase activity. Translation of p27Kip1 is directed by an internal ribosomal entry site (IRES) in the 5′ nontranslated region of p27Kip1 mRNA. Here, we report that polypyrimidine tract-binding protein (PTB) specifically enhances the IRES activity of p27Kip1 mRNA through an interaction with the IRES element. We found that addition of PTB to an in vitro translation system and overexpression of PTB in 293T cells augmented the IRES activity of p27Kip1 mRNA but that knockdown of PTB by introduction of PTB-specific small interfering RNAs (siRNAs) diminished the IRES activity of p27Kip1 mRNA. Moreover, the G1 phase in the cell cycle (which is maintained in part by p27Kip1) was shortened in cells depleted of PTB by siRNA knockdown. 12-O-Tetradecanoylphorbol-13-acetate (TPA)-induced differentiation in HL60 cells was used to examine PTB-induced modulation of p27Kip1 protein synthesis during differentiation. The IRES activity of p27Kip1 mRNA in HL60 cells was increased by TPA treatment (with a concomitant increase in PTB protein levels), but the levels of p27Kip1 mRNA remained unchanged. Together, these data suggest that PTB modulates cell cycle and differentiation, at least in part, by enhancing the IRES activity of p27Kip1 mRNA.

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 La protein is required for efficient translation driven by encephalomyocarditis virus internal ribosomal entry site

1999 ◽  
Vol 80 (12) ◽  
pp. 3159-3166 ◽  
Author(s):  
Yoon Ki Kim ◽  
Sung Key Jang
Keyword(s):  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Protein A ◽  
Internal Ribosomal Entry Site ◽  
Encephalomyocarditis Virus ◽  
Entry Site ◽  
Polypyrimidine Tract Binding Protein ◽  
La Protein ◽  
Ribosomal Entry

Translation of internal ribosomal entry site (IRES)-dependent mRNAs is mediated by RNA-binding proteins as well as canonical translation factors. In order to elucidate the roles of RNA-binding proteins in IRES-dependent translation, the role of polypyrimidine tract-binding protein (PTB) and La protein in encephalomyocarditis virus (EMCV) IRES-dependent translation was investigated. PTB was required for efficient EMCV IRES-driven translation but, intriguingly, an excess of PTB suppressed it. Such a translational suppression by surplus PTB was relieved by addition of La protein. A possible role for La protein in IRES-dependent translation is discussed.

scholarly journals Determination of functional domains in polypyrimidine-tract-binding protein

1998 ◽  
Vol 331 (1) ◽  
pp. 169-175 ◽  
Author(s):  
Young L. OH ◽  
Bumsuk HAHM ◽  
Yoon K. KIM ◽  
Hae K. LEE ◽  
Joo W. LEE ◽  
...  
Keyword(s):  
Amino Acids ◽  
Rna Binding ◽  
Binding Protein ◽  
Biochemical Properties ◽  
Polypyrimidine Tract ◽  
Terminal Part ◽  
Entry Site ◽  
Cytoplasmic Factor ◽  
Polypyrimidine Tract Binding ◽  
Polypyrimidine Tract Binding Protein

Polypyrimidine-tract-binding protein (PTB) is involved in pre-mRNA splicing and internal-ribosomal-entry-site-dependent translation. The biochemical properties of various segments of PTB were analysed in order to understand the molecular basis of the PTB functions. The protein exists in oligomeric as well as monomeric form. The central part of PTB (amino acids 169–293) plays a major role in the oligomerization. PTB contains several RNA-binding motifs. Among them, the C-terminal part of PTB (amino acids 329–530) exhibited the strongest RNA-binding activity. The N-terminal part of PTB is responsible for the enhancement of RNA binding by HeLa cell cytoplasmic factor(s).

scholarly journals The Polypyrimidine Tract Binding Protein Is Required for Efficient Picornavirus Gene Expression and Propagation

2005 ◽  
Vol 79 (10) ◽  
pp. 6172-6179 ◽  
Author(s):  
Paola M. Florez ◽  
October M. Sessions ◽  
Eric J. Wagner ◽  
Matthias Gromeier ◽  
Mariano A. Garcia-Blanco
Keyword(s):  
Gene Expression ◽  
Rna Interference ◽  
Binding Protein ◽  
Viral Gene Expression ◽  
Encephalomyocarditis Virus ◽  
Mammalian Host ◽  
Viral Gene ◽  
Polypyrimidine Tract ◽  
Polypyrimidine Tract Binding ◽  
Polypyrimidine Tract Binding Protein

ABSTRACT Mammalian host factors required for efficient viral gene expression and propagation have been often recalcitrant to genetic analysis. A case in point is the function of cellular factors that trans-activate internal ribosomal entry site (IRES)-driven translation, which is operative in many positive-stranded RNA viruses, including all picornaviruses. These IRES trans-acting factors have been elegantly studied in vitro, but their in vivo importance for viral gene expression and propagation has not been widely confirmed experimentally. Here we use RNA interference to deplete mammalian cells of one such factor, the polypyrimidine tract binding protein, and test its requirement in picornavirus gene expression and propagation. Depletion of the polypyrimidine tract binding protein resulted in a marked delay of particle propagation and significantly decreased synthesis and accumulation of viral proteins of poliovirus and encephalomyocarditis virus. These effects could be partially restored by expression of an RNA interference-resistant exogenous polypyrimidine tract binding protein. These data indicate a critical role for the polypyrimidine tract binding protein in picornavirus gene expression and strongly suggest a requirement for efficient IRES-dependent translation.

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