Sequence requirements for activation of replication by the SV40 transcriptional promoter or enhancer elements

Haas, Melanie; Ramanujam, P.; Chandrasekharappa, Settara C.; Subramanian, K. N.

doi:10.1016/0042-6822(91)90007-x

Cited by 10 publications

(13 citation statements)

References 49 publications

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“…Whereas the auxiliary transcriptional elements (i.e. the 21-bp repeats and the SV40 enhancer) are not essential for viral DNA replication, they can enhance replication activity and are necessary for the efficient SV40 DNA replication in vivo (33,(37)(38)(39). Interestingly, the SV40 enhancer was found to play a critical role in RAX-mediated enhancement of gene expression (Fig.…”

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confidence: 99%

A Novel Role for RAX, the Cellular Activator of PKR, in Synergistically Stimulating SV40 Large T Antigen-dependent Gene Expression

Yang

Ito²,

May

2003

Journal of Biological Chemistry

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The double-stranded (ds) RNA-binding protein RAX was discovered as a stress-induced cellular activator of the dsRNA-dependent protein kinase (PKR), a key regulator of protein synthesis in response to viral infection and cellular stress. We now report a novel function of RAX, independent of PKR, to enhance SV40 promoter (origin)/enhancer-dependent gene expression. Several mammalian cell lines including COS-7, CV-1, and HeLa cells were tested. Results reveal that the SV40 large T antigen is required for RAX-mediated, synergistic enhancement of gene expression. RAX augments SV40 regulatory element-dependent DNA replication and transcription. The mechanism requires the SV40 enhancer, a viral transcriptional element that is necessary for efficient SV40 DNA replication in vivo. Mutational analysis reveals that the dsRNA-binding domains of RAX are required for the gene expression enhancing function. Thus, in addition to stimulating PKR activity, RAX can positively regulate both SV40 large T antigen-dependent DNA replication and transcription in a mechanism that may alter the interaction of the cellular factor(s) with the SV40 enhancer via the dsRNA-binding domains of RAX. This novel function of RAX may have implications for regulation of mammalian DNA replication and transcription because of the many similarities between the viral and cellular processes.

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confidence: 99%

A Novel Role for RAX, the Cellular Activator of PKR, in Synergistically Stimulating SV40 Large T Antigen-dependent Gene Expression

Yang

Ito²,

May

2003

Journal of Biological Chemistry

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“…They used these constructs in the same type of replication assay used for the present study (transient transfection of COS-1 cells) to show that the AP-1 site increases replication efficiency in the context of the 72-bp transcriptional enhancer region on the late side of wild-type SV40 ori. Disruption of the AP-1 site decreased RRE by 35 to 38 percent (27). The present study demonstrates that the AP-1 site in wild-type SV40, when isolated from the other transcription factor-binding sites of the 72-bp enhancer, had little effect on replication efficiency (pC200 compared with pOri3x21).…”

Section: Discussionmentioning

confidence: 74%

“…Haas et al (27) made two separate plasmid constructs, each with three contiguous substitution mutations in the AP-1 site of the SV40 72-bp transcriptional enhancer. The enhancer also contains binding sites for several other transcription factors.…”

Section: Discussionmentioning

confidence: 99%

“…pC200 (38), containing three pairs of Sp1 sites (one pair in each of its three 21-bp repeats) and an AP-1 site, produces the wild-type maximum replication efficiency from ori (38,52). When the AP-1 site on the late-transcription side of the three Sp1 pairs is deleted from its natural context in the 72-bp transcriptional enhancer, replication efficiency is decreased (27). It was of interest to determine whether the AP-1 site found on the late-transcription side of the three pairs of Sp1 transcription factor-binding sites in wild-type SV40 increases replication in the absence of the remainder of the 72-bp transcriptional enhancer.…”

Section: Vol 75 2001mentioning

confidence: 99%

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DNA Replication Efficiency Depends on Transcription Factor-Binding Sites

Turner

Woodworth

2001

J Virol

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Naturally arising variants of simian virus 40 (SV40), generated by serial passage of the virus at high multiplicities of infection, provide important insight into the role of transcription factor-binding sites in enhancing DNA replication. Although the variants that arise from numerous recombination events are the result of selective pressure to replicate more efficiently than the other variants in the infection, there is no transcription pressure. Therefore, it is interesting that a minimum of two viral Sp1 transcription factorbinding sites are retained and that host AP-1 and NF-1 transcription factor-binding sites are incorporated into the 100-bp regulatory region that maximizes DNA replication in these variants. We cotransfected COS-1 cells (that provide viral large T antigen for DNA replication) to examine the effect of transcription factor-binding sites on the replication of plasmid constructs that contain the SV40 origin of replication (ori). The level of relative replication efficiency (RRE) depends on the number and type of transcription factor-binding sites. Replication increases as the number of transcription factor-binding sites increases within the regulatory region of the variants; AP-1 sites are more effective than NF-1 transcription factor-binding sites. Competition between constructs in transfections magnifies the difference in their RREs. The results indicate that transcription factor-binding sites play an important role in enhancing DNA replication.Simian virus 40 (SV40) DNA is replicated by host cell machinery (reviewed in references 5 and 11) and one virally encoded protein, large T antigen (T-ag) (6,45,50,56). SV40 DNA replication is bidirectional (7, 17) from a 64-bp core origin of DNA replication (ori) (4,14,25,45,52). This ori sequence consists of a 15-bp early palindrome, a 27-bp palindrome, and a 17-bp AT-rich region (8). Four pentanucleotides in the central 27-bp palindromic region of ori are binding sites for T-ag (9, 49, 57). Additional regulatory sequences within 180 bp on the late transcription side of ori include three 21-bp repeats (16) and a 72-bp transcriptional enhancer (2,20,23,43). Each 21-bp repeat contains two hexameric GC boxes, which are binding sites for the transcription factor Sp1 (15) and weak binding sites for T-ag (57). The transcriptional enhancer contains a number of protein-binding sites; of these, a binding site for the transcription factor AP-1 is the closest to ori (31,34,63).The involvement of transcription factor-binding sites and the way in which they are arranged within regions that regulate DNA replication are interesting for several reasons. Some arrangements of AP-1 and Sp1 transcription factor-binding sites seem to be favored in evolutionary variants (37). Evolutionary variants arise when SV40 is serially passaged at high multiplicities of infection, whereby recombination leads to new viral species containing deleted and duplicated viral DNA and substituted host DNA. In several SV40 evolutionary variants (ev1101, ev1103, ev1104, and ev1108), the incor...

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“…In particular, both Oct-i and Oct-2 can stimulate the replication of adenovirus DNA in vitro (25,26) and the octamer motif in the simian virus 40 (SV40) enhancer has been implicated in SV40 viral DNA replication in vivo (29). The ability of transcription factors to stimulate viral replication is independent oftranscription (26,28,30).…”

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confidence: 99%