scholarly journals Heat Shock Protein A6, a Novel HSP70, Is Induced During Enterovirus A71 Infection to Facilitate Internal Ribosomal Entry Site-Mediated Translation

2021 ◽  
Vol 12 ◽  
Author(s):  
Yu-Siang Su ◽  
Lih-Hwa Hwang ◽  
Chi-Ju Chen
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Neurological Diseases ◽  
Internal Ribosomal Entry Site ◽  
Viral Proteins ◽  
Cellular Protein ◽  
Encephalomyocarditis Virus ◽  
Entry Site ◽  
Enterovirus A71 ◽  
Ribosomal Entry

Enterovirus A71 (EV-A71) is a human pathogen causing hand, foot, and mouth disease (HFMD) in children. Its infection can lead to severe neurological diseases or even death in some cases. While being produced in a large quantity during infection, viral proteins often require the assistance from cellular chaperones for proper folding. In this study, we found that heat shock protein A6 (HSPA6), whose function in viral life cycle is scarcely studied, was induced and functioned as a positive regulator for EV-A71 infection. Depletion of HSPA6 led to the reductions of EV-A71 viral proteins, viral RNA and virions as a result of the downregulation of internal ribosomal entry site (IRES)-mediated translation. Unlike other HSP70 isoforms such as HSPA1, HSPA8, and HSPA9, which regulate all phases of the EV-A71 life, HSPA6 was required for the IRES-mediated translation only. Unexpectedly, the importance of HSPA6 in the IRES activity could be observed in the absence of viral proteins, suggesting that HSPA6 facilitated IRES activity through cellular factor(s) instead of viral proteins. Intriguingly, the knockdown of HSPA6 also caused the reduction of luciferase activity driven by the IRES from coxsackievirus A16, echovirus 9, encephalomyocarditis virus, or hepatitis C virus, supporting that HSPA6 may assist the function of a cellular protein generally required for viral IRES activities.

scholarly journals Construction of a bifunctional mRNA in the mouse by using the internal ribosomal entry site of the encephalomyocarditis virus.

1992 ◽  
Vol 12 (8) ◽  
pp. 3636-3643 ◽  
Author(s):  
D G Kim ◽  
H M Kang ◽  
S K Jang ◽  
H S Shin
Keyword(s):  
Es Cells ◽  
Internal Ribosomal Entry Site ◽  
Embryonic Stem ◽  
Mouse Embryos ◽  
Encephalomyocarditis Virus ◽  
Vector System ◽  
Chimeric Mouse ◽  
Entry Site ◽  
Cell Extracts ◽  
Ribosomal Entry

Picornaviral mRNAs have been shown to possess special structures in their 5' nontranslated regions (5'NTRs) that provide sites for internal binding of ribosomes and thus direct cap-independent translation. The translational cis-acting elements for ribosomal internal entry into the 5'NTR of encephalomyocarditis virus (EMCV), a member of family Picornaviridae, have been named the internal ribosomal entry site (IRES). All of the published experiments regarding the IRES function of the picornavirus 5'NTR, however, were performed with cell extracts in vitro or with tissue culture cells in transient assay systems. In this study, we examined the IRES function of the EMCV 5'NTR in chimeric mouse embryos and demonstrated that this element does in fact work stably in mouse embryos as well as in embryonic stem (ES) cells. By using a dicistronic vector, pWH8, consisting of a promoter-driven neomycin resistance gene (neo) followed by the EMCV 5'NTR-lacZ sequence, we showed that more than half of the ES cells made G418 resistant by the vector stained positive for beta-galactosidase (beta-gal). On Northern (RNA) blots, all of the clones analyzed revealed a transcript of the expected size containing both the beta-gal and the neo cistrons. These results indicate that dicistronic mRNAs are produced from the stably integrated vector in those ES clones and that both of the cistrons are translated to produce functional proteins. The chimeric embryos derived from these ES clones also stained positive for beta-gal, suggesting that the bifunctional mRNAs are active in the embryos. This dicistronic vector system provides a novel tool by which to obtain temporally and spatially coordinated expression of two different genes driven by a single promoter in a single cell in mice.

scholarly journals Requirements for Assembly of Poliovirus Replication Complexes and Negative-Strand RNA Synthesis

2001 ◽  
Vol 75 (8) ◽  
pp. 3841-3850 ◽  
Author(s):  
Natalya L. Teterina ◽  
Denise Egger ◽  
Kurt Bienz ◽  
David M. Brown ◽  
Bert L. Semler ◽  
...  
Keyword(s):  
Rna Synthesis ◽  
Internal Ribosomal Entry Site ◽  
Rna Replication ◽  
Viral Proteins ◽  
Encephalomyocarditis Virus ◽  
Minus Strand ◽  
Entry Site ◽  
Sequence Production ◽  
Positive Strand Rna

ABSTRACT HeLa cells were transfected with several plasmids that encoded all poliovirus (PV) nonstructural proteins. Viral RNAs were transcribed by T7 RNA polymerase expressed from recombinant vaccinia virus. All plasmids produced similar amounts of viral proteins that were processed identically; however, RNAs were designed either to serve as templates for replication or to contain mutations predicted to prevent RNA replication. The mutations included substitution of the entire PV 5′ noncoding region (NCR) with the encephalomyocarditis virus (EMCV) internal ribosomal entry site, thereby deleting the 5′-terminal cloverleaf-like structure, or insertion of three nucleotides in the 3Dpol coding sequence. Production of viral proteins was sufficient to induce the characteristic reorganization of intracellular membranes into heterogeneous-sized vesicles, independent of RNA replication. The vesicles were stably associated with viral RNA only when RNA replication could occur. Nonreplicating RNAs localized to distinct, nonoverlapping regions in the cell, excluded from the viral protein-membrane complexes. The absence of accumulation of positive-strand RNA from both mutated RNAs in transfected cells was documented. In addition, no minus-strand RNA was produced from the EMCV chimeric template RNA in vitro. These data show that the 5′-terminal sequences of PV RNA are essential for initiation of minus-strand RNA synthesis at its 3′ end.

scholarly journals cis-Acting Elements of the Encephalomyocarditis Virus Internal Ribosomal Entry Site

Virology ◽  
1995 ◽  
Vol 214 (2) ◽  
pp. 660-663 ◽  
Author(s):  
GARY W. WITHERELL ◽  
CARLA S. SCHULTZ-WITHERELL ◽  
ECKARD WIMMER
Keyword(s):  
Internal Ribosomal Entry Site ◽  
Encephalomyocarditis Virus ◽  
Entry Site ◽  
Cis Acting ◽  
Ribosomal Entry

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.

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