Exploring the Transcriptional Influence of Upstream Elements on a Human U6 Small Nuclear RNA Gene Promoter
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Date
1996
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Abstract
Past studies have shown that the promoter of a human U6 small nuclear RNA gene contains two distal elements that increase the transcriptional level of the gene. One of these elements, termed OCT, is an octamer motif that binds the recombinant Oct-1 transcription factor. In addition, another sequence element, termed NONOCT, is located nearby and also appears to stimulate transcription in conjunction with the Oct element. This NONOCT element does not bind the OctI transcription factor, but rather another transcription factor found in crude cellular extracts. Using the wildtype promoter containing both the OCT and NONOCT elements, transfection and in vitro transcription experiments have demonstrated an increased level of transcriptional activation of the U6 snRNA promoter.
In an effort to further characterize the influence of these elements, plasmid constructs containing the U6 snRNA proximal promoter and a cytidine-free oligonucleotide reporter gene were used in transcriptional assays. The individual OCT and NONOCT elements were ligated immediately upstream of the U6 proximal promoter into separate plasmids, as was a combined OCT/NONOCT element. Selected plasmids were then utilized for in vivo transfection and in vitro transcription assays to determine the effects of the individual elements, their orientation, and their dosage on the transcriptional activation of the promoter. The presence of both of these elements results in an increased level of transcriptional activity by the U6 snRNA promoter over the promoter that does not possess either of these elements. Furthermore, the OCT element has a greater effect on the transcriptional level than does the NONOCT element. A promoter with both elements combined, however, shows slightly more activation of the promoter than the OCT element alone, indicating an additive effect of the influences of both elements. However, there appears to be no additional effects related to the dosage or orientation of these upstream elements.
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Program year: 1996/1997
Digitized from print original stored in HDR
Digitized from print original stored in HDR
Keywords
NONOCT, OCT, sequence elements, transcriptional level