The human U snRNA promoter and enhancer do not direct synthesis of messenger RNA

Dahlberg, James E.; Schenborn, Elaine T.

doi:10.1093/nar/16.13.5827

Cited by 37 publications

(23 citation statements)

References 32 publications

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“…In Xenopus oocytes, transcripts initiated at Pol II-specific U snRNA promoters appear not to be polyadenylated (34). Moreover, it was reported that snRNA promoters are unable to direct the synthesis of functional polyadenylated mRNAs in mammalian cells (10). The failure to produce polyadenylated mRNAs in mammalian cells may be due to the fact that transcription initiated at U snRNA gene promoters terminates at cryptic 3' box signals (34 (1,20,23,34,57), both the coding region and the 3'-endadjacent sequence are required for formation of U snRNA 3' ends (see also above).…”

Section: Resultsmentioning

confidence: 99%

Activity of chimeric U small nuclear RNA (snRNA)/mRNA genes in transfected protoplasts of Nicotiana plumbaginifolia: U snRNA 3'-end formation and transcription initiation can occur independently in plants.

Connelly¹,

Filipowicz²

1993

Mol. Cell. Biol.

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Formation of the 3' ends of RNA polymerase H (Pol H)-specific U small nuclear RNAs (U snRNAs) in vertebrate cells is dependent upon transcription initiation from the U snRNA gene promoter. Moreover, U snRNA promoters are unable to direct the synthesis of functional polyadenylated mRNAs. In this work, we have investigated whether U snRNA 3'-end formation and transcription initiation are also coupled in plants.We have first characterized the requirements for 3'-end formation of an Arabidopsis U2 snRNA expressed in transfected protoplasts of Nicotiana plwmbaginifolia. We found that the 3'-end-adjacent sequence CA (N)310AGTNNAA, conserved in plant Pol lI-specific U snRNA genes, is essential for the 3'-end formation of U2 transcripts and, similar to the vertebrate 3' box, is highly tolerant to mutation. The 3'-flanking regions of an Arabidopsis U5 and a maize U2 snRNA gene can effectively substitute for the Arabidopsis U2 3'-end formation signal, indicating that these signals are functionally equivalent among different Pol lI-transcribed snRNA genes. The plant U snRNA 3'-end formation signal can be recognized irrespective of whether transcription initiation occurs at U snRNA or mRNA gene promoters, although efficiency of 3' box utilization is higher when transcription initiation occurs at the U snRNA promoter. Moreover, transcripts initiated from the U2 gene promoter can be spliced and polyadenylated. Transcription from a Pol r-specific plant U snRNA gene promoter is not compatible with polyadenylation. Finally, we reveal that initiation at a Pol H-specific plant U snRNA gene promoter can occur in the absence of the snRNA coding region and a functional snRNA 3'-end formation signal, demonstrating that these sequences play no role in determining the RNA polymerase specificity of plant U snRNA genes.

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Section: Resultsmentioning

confidence: 99%

Activity of chimeric U small nuclear RNA (snRNA)/mRNA genes in transfected protoplasts of Nicotiana plumbaginifolia: U snRNA 3'-end formation and transcription initiation can occur independently in plants.

Connelly¹,

Filipowicz²

1993

Mol. Cell. Biol.

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“…Moreover, the formation of the 3' ends of the snRNAs is dependent on the initiation of transcription from an snRNA gene promoter (4,13,14,28). Because of the unique properties of snRNA transcription complexes, the promoter elements of snRNA genes are not functionally interchangeable with comparable elements of mRNA genes (5,7,13,39,41 (3,24,25,27,36); it also is required for proper 3' end formation (13,28,33). Second, the distal region is an enhancerlike element that is required for a high level of snRNA gene expression and for the formation of a stable transcription complex (3, 23-25, 27, 35, …”

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confidence: 99%

“…Moreover, the formation of the 3' ends of the snRNAs is dependent on the initiation of transcription from an snRNA gene promoter (4,13,14,28). Because of the unique properties of snRNA transcription complexes, the promoter elements of snRNA genes are not functionally interchangeable with comparable elements of mRNA genes (5,7,13,39,41). Finally, vertebrate snRNA genes are not accurately transcribed under ordinary in vitro transcription conditions with soluble HeLa cell extracts (26,44).…”

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confidence: 99%

Octamer and SPH motifs in the U1 enhancer cooperate to activate U1 RNA gene expression.

et al. 1990

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The transcriptional enhancer of a chicken Ul small nuclear RNA gene has been shown to extend over approximately 50 base pairs of DNA sequence located 180 to 230 base pairs upstream of the Ul transcription initiation site. It is composed of multiple functional motifs, including a GC box, an octamer motif, and a novel SPH motif. The contributions of these three distinct sequence motifs to enhancer function were studied with an oocyte expression assay. Under noncompetitive conditions in oocytes, the SPH motif is capable of stimulating Ul RNA transcription in the absence of the other functional motifs, whereas the octamer motif by itself lacks this ability. However, to form a transcription complex that is stable to challenge by a second competing small nuclear RNA transcription unit, both the octamer and SPH motifs are required. The GC box, although required for full enhancer activity, is not essential for stable complex formation in oocytes. Site-directed mutagenesis was used to study the DNA sequence requirements of the SPH motif. Functional activity of the SPH motif is spread throughout a 24-base-pair region 3' of the octamer but is particularly dependent upon sequences near an SphI restriction site located at the center of the SPH motif. Using embryonic chicken tissue as a source material, we identified and partially purified a factor, termed SBF, that binds sequence specifically to the SPH motif of the Ul enhancer. The ability of this factor to recognize and bind to mutant enhancer DNA fragments in vitro correlates with the functional activity of the corresponding enhancer sequences in vivo.The small nuclear RNAs (snRNAs) of the U family are evolutionarily conserved and metabolically stable RNA molecules present in the nuclei of eucaryotic cells. Considerable evidence exists that the Ul, U2, U4, U5, and U6 snRNAs are involved in the splicing of mRNA precursors (37). With the exception of U6, the snRNAs are synthesized by RNA polymerase II (6) and have a distinctive N2,N2,N7-trimethylguanosine cap structure (34).The genes that code for the vertebrate snRNAs are usually present in multiple copies per genome and have several features that distinguish them from protein-coding genes. The promoter regions of snRNA genes lack transcription signals normally found upstream of genes transcribed by RNA polymerase II (e.g., they lack TATA and CCAAT boxes). Nevertheless, they contain two distinct and evolutionarily conserved cis-acting regulatory regions within their 5'-flanking DNA sequences that are important for snRNA gene expression: a proximal region centered near position -55 relative to the transcription initiation site and a distal region located near position -200 (reviewed in references 6 and 32). Moreover, the formation of the 3' ends of the snRNAs is dependent on the initiation of transcription from an snRNA gene promoter (4,13,14,28). Because of the unique properties of snRNA transcription complexes, the promoter elements of snRNA genes are not functionally interchangeable with comparable elements of mRNA genes...

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“…The octamer site is also important for transcription of the snRNA genes although their expression is not restricted to lymphoid cells (Mattaj et al, 1985;Ares et al, 1987;Ciliberto et al, 1987;Janson et al, 1987Janson et al, , 1989Dahlberg and Schenborn, 1988;Tanaka et al, 1988). Transcription of human U2 genes is controlled by a proximal sequence element (PSE) and a distal sequence element (DSE) which is also called the U2 enhancer (Westin et al, 1984;Ares et al, 1985;Mangin et al, 1986; for review see Dahlberg and Lund, 1987).…”

Section: Introductionmentioning

confidence: 99%

Both Oct-1 and Oct-2A contain domains which can activate the ubiquitously expressed U2 snRNA genes.

et al. 1991

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The U2 snRNA genes, which are transcribed by RNA polymerase II at high levels in all tissues examined, require both a distal and a proximal sequence element for efficient expression. The distal sequence element which has many properties in common with transcriptional enhancers contains, in addition to Sp1 binding sites, an octamer binding site which mediates activation through interactions with the ubiquitous transcription factor Oct‐1. In the present study we have attempted to answer the question whether Oct‐1 contains a unique activating domain which is required for activation of snRNA genes or whether ubiquitously expressed and lymphoid specific octamer binding factors both have the capacity to activate snRNA transcription. Our results show that in the presence of Oct‐1, overexpression of Oct‐2A in HeLa or COS1 cells neither inhibits nor stimulates transcription of U2 constructions which contain octamer binding sites with or without an adjacent Sp1 binding site. Moreover, an Oct‐2A‐‐GAL4 fusion protein in which the DNA binding domain of Oct‐2A was substituted for by the one of the yeast transcription activator GAL4 activates transcription of a human U2 snRNA gene in which the octamer binding site was replaced by a GAL4 binding site. From the results it is concluded that both Oct‐1 and Oct‐2A contain domains which can activate the ubiquitously expressed U2 snRNA genes.

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The human U snRNA promoter and enhancer do not direct synthesis of messenger RNA

Cited by 37 publications

References 32 publications

Activity of chimeric U small nuclear RNA (snRNA)/mRNA genes in transfected protoplasts of Nicotiana plumbaginifolia: U snRNA 3'-end formation and transcription initiation can occur independently in plants.

Activity of chimeric U small nuclear RNA (snRNA)/mRNA genes in transfected protoplasts of Nicotiana plumbaginifolia: U snRNA 3'-end formation and transcription initiation can occur independently in plants.

Octamer and SPH motifs in the U1 enhancer cooperate to activate U1 RNA gene expression.

Both Oct-1 and Oct-2A contain domains which can activate the ubiquitously expressed U2 snRNA genes.

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