Heterogeneous Nuclear Ribonucleoprotein A1 Binds to the 3′-Untranslated Region and Mediates Potential 5′-3′-End Cross Talks of Mouse Hepatitis Virus RNA

Abstract

The genome of mouse hepatitis virus (MHV) is a singlestranded, linear, positive-sense, polyadenylated RNA of approximately 31 kb in length (22,24,39). All of the viral proteins are translated from subgenomic mRNAs, except those encoded by the first open reading frame, which are translated from the genome-sized RNA. In MHV-infected cells, six or seven subgenomic mRNAs are transcribed, all of which contain a common leader sequence derived from the 5Ј end of the genome, as well as a common 3Ј end including a 302-to 305-nucleotide (nt)-long untranslated region (3Ј-UTR) (21). When MHV is passaged at a high multiplicity of infection in cell culture, defective-interfering (DI) RNAs which represent deletion mutants of the MHV genome are frequently generated (33, 36). Since DI RNAs can replicate in the presence of a helper virus, they must retain all signals necessary for MHV genome replication.Comparison of various MHV DI RNAs showed that all retain various lengths of both the 5Ј and 3Ј ends of the viral genome (34,35,37,43). Mapping studies of MHV DI RNAs have further revealed that 400 to 859 nt from the 5Ј end and 436 nt from the 3Ј end of the genome are required for DI RNA replication (17, 29). However, only 55 nt from the 3Ј end plus the poly(A) tail are required for synthesis of the negative strand of MHV RNA (30). Thus, it stands to reason that the replication signal from the 5Ј end and the remaining replication signal (nt 55 to 436) from the 3Ј end of the MHV genome are involved in synthesis of the positive-strand RNA. Moreover, since positive-strand RNA synthesis begins from the 5Ј end of the genome, and the 3Ј end will be the last region of the genome reached by the viral polymerase, the replication signal at the 3Ј end likely interacts with signals at the 5Ј end to exert its effect on RNA synthesis. Based on this reasoning, the 5Ј and 3Ј ends of the genome have been proposed to interact during viral RNA replication so that the 3Ј-end sequence can affect the initiation of RNA synthesis (20). Similar observations have also been made for the regulation of MHV subgenomic mRNA transcription (28). Typically, the regulatory sequence for the synthesis of a particular RNA strand resides on the complementary (template) strand; i.e., the signal for synthesizing the positive strand resides on the negative strand, and vice versa. However, the regulatory signals may also reside on the same strand. For example, in brome mosaic virus (BMV) and poliovirus, cis elements that affect synthesis of the positivestrand RNA are mapped to the 5Ј end of the positive-strand RNA (2, 9, 40). Presumably this is due to the possibility that double-stranded replicative-form RNA is used as the template for positive-strand RNA synthesis. Thus, RNA synthesis may be regulated by 5Ј-3Ј-end interaction of both RNA strands.Although 5Ј-3Ј-end interactions of MHV RNA have been suggested from functional studies (28), no apparent sequence complementarity exists between these two regions. Therefore, interaction between the 5Ј and 3Ј ends likely involves p...

Characterization of Emerging European-Like Porcine Reproductive and Respiratory Syndrome Virus Isolates in the United States

“…The 5Ј UTR, critical in replication, transcription, and translation (24), was shown to possess only 93.2% nucleotide identity to LV, yet the 3Ј UTR sequence was accurately maintained (98.2% identity). The reason for this disparity is unknown, as evidence suggests that these two regions may be in close proximity during viral replication (23,49). NSP2 has been reported to be the most variable part of the genome (11,61), and the ORF 1a sequence of EuroPRRSV was consistent with that notion, displaying a 17-aa deletion within the NSP2 protein, the only deletion or insertion observed in relation to the LV genomic sequence.…”

A phosphorothioate antisense oligodeoxynucleotide specifically inhibits coxsackievirus B3 replication in cardiomyocytes and mouse hearts

“…33,34 Such interaction is likely mediated by several host cell proteins, such as poly-(A)-binding protein, an important trans-acting factor required for viral translation and replication. 10 Thus, targeting the terminus of 3 0 UTR by AS-7 will interfere with 5 0 -and 3 0 -UTR end interactions of viral RNA, which in turn inhibit viral transcription and translation. The data reported here have confirmed that AS-7 confers specific activity in both cardiomyocytes and in the mouse model wherein the pathophysiological conditions are much closer to a clinical environment.…”

“…9 Therefore, efficient blocking of the 3 0 terminal region of CVB3 RNA may inhibit the binding of cellular translation or transcription initiation factors, thereby preventing the formation of a replication unit of a circular viral RNA. 10 The potential of oligodeoxynucleotides to act as antisense agents that inhibit the replication of the Rous sarcoma virus was discovered in 1978. 11 As a novel class of therapeutic agents to selectively block or inhibit gene expression, antisense oligodeoxynucleotides (AS-ODNs) have attracted great interest in the development of drugs and gene functional studies.…”

Norovirus Genome Circularization and Efficient Replication Are Facilitated by Binding of PCBP2 and hnRNP A1

“…Given that anti-hnRNP A1 and anti-PCBP2 were able to reduce complex formation and that both proteins bind to the MNV-1 genomic RNA and have been implicated in the stabilization of viral RNA-RNA interactions (27,49), we next examined if these proteins could promote the interaction of the 5= and the 3= ends of the MNV-1 genomic RNA. Therefore, a coprecipitation assay was performed using biotin-labeled 5=-end and ␣-32 P-labeled 3=-UTR RNA probes in the presence of both PCBP2-His and His-hnRNP A1 recombinant proteins (Fig.…”