The differential inhibitory effect of α‐amanitin on the synthesis of low molecular weight RNA components in BHK cells

Frederiksen, Sune; Hellung‐Larsen, Per; Jensen, Elisabeth Gram

doi:10.1016/0014-5793(78)80338-x

Cited by 50 publications

(16 citation statements)

References 29 publications

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“…For simplicity, only one copy of the SV40 B element is shown, and the RNA polymerase II complex itself is not represented. The pattern of U1 and U2 transcription sensitivity to a-amanitin demonstrates that these genes are transcribed by an RNA polymerase containing the large subunit of RNA polymerase II (Frederiksen et al 1978;Gram Jensen et al 1979). It should be noted, however, that the RNA polymerase II complex that transcribes snRNA genes may differ slightly from the RNA polymerase II that transcribes mRNA-encoding genes.…”

Section: A Model For Octamer Motif Function In Different Promoters Anmentioning

confidence: 99%

“…In addition to being very highly transcribed by RNA polymerase II (Frederiksen et al 1978;Gram Jensen et al 1979;Murphy et al 1982), these genes share a number of unusual characteristics when compared to mRNA-encoding genes. First, the promoters lack a TATA box and instead contain a snRNA-specific proximal element located 40-60 bp upstream of the transcriptional start site (Skuzeski et al 1984;Ares et al 1985;Ciliberto et al 1985;Mattaj et al 1985;Mangin et al 1986;Murphy et al 1987;Hernandez and Lucito 1988).…”

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confidence: 99%

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Activation of the U2 snRNA promoter by the octamer motif defines a new class of RNA polymerase II enhancer elements.

Tanaka¹,

Grossniklaus²,

Herr³

et al. 1988

Genes & Development

166

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The recent discovery that the activation domains of transcriptional activators (e.g., GAL4) from a number of species are interchangeable has led to the concept of a general mechanism for activation of RNA polymerase II genes. We have examined the different activities of the SV40 octamer motif ATGCAAAG in B cells and in HeLa cells in the context of either the [3-globin promoter, a TATA-box-containing mRNA promoter, or the U2 snRNA promoter, which contains a snRNA-specific proximal element. In the context of the ~-globin promoter, the octamer motif is a B-cell-specific enhancer element, whereas it is a ubiquitous enhancer element for the U2 snRNA promoter. The U2 promoter is unique in that it is not activated by enhancer elements that activate the [3-globin promoter, and a hybrid U2 promoter containing the upstream activating sequence UASG is not stimulated by a yeast GAL4 trans-activator. Together, these observations suggest that in the context of the U2 promoter, the octamer motif defines a new class of RNA polymerase II enhancer elements, which bind transcription factors that trans-activate gene expression by a different mechanism than the general mechanism mentioned above. These results are discussed in light of the possibility that the ubiquitous octamer binding protein Oct-1 and the B-cell-specific octamer binding protein Oct-2 are involved in the activation of the U2 and ~-globin promoters, respectively.

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Section: A Model For Octamer Motif Function In Different Promoters Anmentioning

confidence: 99%

mentioning

confidence: 99%

Activation of the U2 snRNA promoter by the octamer motif defines a new class of RNA polymerase II enhancer elements.

Tanaka¹,

Grossniklaus²,

Herr³

et al. 1988

Genes & Development

166

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“…The Ul, U2, and U3 small nuclear RNA (snRNA) genes are thought to be transcribed by RNA polymerase II since their transcription is sensitive to low levels of a-amanitin (10,35) and the snRNAs are capped. However, there are two striking differences between the synthesis of other RNA polymerase II transcripts (mRNAs) and that of the snRNAs.…”

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confidence: 99%

The highly conserved U small nuclear RNA 3'-end formation signal is quite tolerant to mutation.

Ach¹,

Weiner²

1987

Mol. Cell. Biol.

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Formation of the 3' end of Ul and U2 small nuclear RNA (snRNA) precursors is directed by a conserved sequence called the 3' box located 9 to 28 nucleotides downstream of all metazoan Ul to U4 snRNA genes sequenced so far. Deletion of part or all of the 3' box from human Ul and U2 genes drastically reduces 3'-end formation. To define the essential nucleotides within this box that direct 3'-end formation, we constructed a set of point mutations in the conserved residues of the human Ul 3' box. The ability of the various mutations to direct 3'-end formation was tested by microinjection into Xenopuws oocytes and transfection into HeLa cells. We found that the point mutations had diverse effects on 3'-end formation, ranging from no effect at all to severe inhibition; however, no single or double point mutation we tested completely eliminated 3'-end formation. We also showed that a rat U3 3' flank can effectively substitute for the human Ul 3' flank, indicating that the 3' boxes of the different U snRNA genes are functionally equivalent.The Ul, U2, and U3 small nuclear RNA (snRNA) genes are thought to be transcribed by RNA polymerase II since their transcription is sensitive to low levels of a-amanitin (10, 35) and the snRNAs are capped. However, there are two striking differences between the synthesis of other RNA polymerase II transcripts (mRNAs) and that of the snRNAs. First, snRNA promoters lack sequence homology with the TATA and CAAT boxes found in most mRNA promoters but share several unique conserved sequences among themselves (1,28,35,(40)(41)(42)(43). Second, the 3' ends of snRNAs are not polyadenylated and seem to be formed by a different mechanism from that of mRNA 3' ends.The 3' ends of most mRNAs are formed by endonucleolytic cleavage of a long precursor RNA followed by polyadenylation. The cleavage reaction is directed both by a highly conserved AAUAAA sequence found 10 to 30 nucleotides (nt) upstream of the poly(A) addition site, as well as by sequences located downstream of the cleavage site (13, 15, 32; for a review, see reference 2). Evidence suggests that this cleavage and polyadenylation step may involve a small nuclear ribonucleoprotein (16,33,34). The 3' ends of histone mRNAs are not polyadenylated but are also formed by an RNA processing event. This processing is directed by a highly conserved GC-rich hairpin at the 3' end of the mRNA followed by a purine-rich block about 15 nt further downstream. This processing event is known to require U7 snRNA, at least for H3 mRNA (11,12,39; for a review, see reference 2).The 3' ends of mature Ul, U2, and U3 snRNAs are formed in at least two steps. First, precursors are formed with a few additional nucleotides at their 3' end. These precursors are then processed into the mature snRNA (3,7,18,27,41,44,45). Two pieces of evidence now indicate that the 3' ends of the snRNA precursors are formed by either termination of transcription or an RNA processing event directly coupled to transcription. First, run-on transcription in isolated nuclei does not proceed fu...

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“…These RNAs are encoded by multiple genes and contain an unusual 5' cap structure, 2,2,7 trimethyl guanosine (3). These RNAs are synthesized by RNA polymerase II, as measured by the sensitivity of their synthesis to low concentrations of aamanitin (8,25,33). An exception is U6 RNA, which lacks the cap structure found at the 5' ends of other U RNAs and is believed to be transcribed by RNA polymerase III (13,32).…”

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confidence: 99%

Synthesis of U1 RNA in isolated mouse cell nuclei: initiation and 3'-end formation.

Lobo¹,

Marzluff²

1987

Mol. Cell. Biol.

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The transcription of Ul RNA genes was studied in isolated nuclei from mouse myeloma cells. Using a cloned Ulb gene as a probe, we showed that isolated nuclei synthesize both Ulb and Ula RNA. The Ul RNAs were initiated in vitro, as measured by incorporation of adenosine 5'-O-(2-thiotriphosphate) into Ul RNA. There was transcription of the 3'-flanking region but no transcription of regions directly 5' to the Ul genes. In addition to Ul RNAs of the correct length which were released from the nuclei, there were larger RNAs, presumably resulting from transcription into the 3'-flanking region, which were retained in the nuclei. Chase experiments showed that these longer transcripts were not precursors to mature Ul RNA, a finding consistent with the idea that 3'-end formation is coincident with transcription. During the chase, there was maturation of the 3' ends of Ula and Ulb RNAs from slightly longer precursors. In addition to accurate transcription of Ul RNA, there was also synthesis of U2 and U3 RNA. All three of these RNAs were transcribed by RNA polymerase II, as measured by their sensitivity to a-amanitin.The U series of small nuclear RNAs (snRNAs) is one of the most abundant transcripts in mammalian cells. These RNAs are encoded by multiple genes and contain an unusual 5' cap structure, 2,2,7 trimethyl guanosine (3). These RNAs are synthesized by RNA polymerase II, as measured by the sensitivity of their synthesis to low concentrations of aamanitin (8,25,33). An exception is U6 RNA, which lacks the cap structure found at the 5' ends of other U RNAs and is believed to be transcribed by RNA polymerase III (13,32). Some aspects of the synthesis of Ul, U2, and U3 RNAs differ from those of other RNAs synthesized by RNA polymerase II. While cell-free systems have been described which transcribe most other genes accurately, the cell-free systems currently available from mammalian cells do not accurately transcribe the Ul or U2 genes (28, 39). We have previously described the development of both nuclear (25) and DNA-dependent (26) systems from sea urchin embryos which transcribe the sea urchin Ul RNA gene accurately.The promoters of the vertebrate U snRNAs differ from those of other genes transcribed by polymerase II. There is a sequence about 200 nucleotides 5' to the gene which is essential for transcription in vivo (19) and on injection of the genes into Xenopus oocytes (29,33,39). When the genes are used as a template in a DNA-dependent system, there is transcription which initiates about 25 bases downstream from this upstream promoter element (as if it were functioning like a TATAA box in this system) but no transcription which initiates at the proper start site (28). The promoters of the sea urchin U RNA genes are not utilized in Xenopus oocytes (37), unlike the promoters of other sea urchin genes transcribed by RNA polymerase II.The formation of the 3' end of the U snRNAs is unusual in two respects. There is initial formation of a transcript a few nucleotides longer than the mature RNA (6,18,41 (18).Dissecting...

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The differential inhibitory effect of α‐amanitin on the synthesis of low molecular weight RNA components in BHK cells

Cited by 50 publications

References 29 publications

Activation of the U2 snRNA promoter by the octamer motif defines a new class of RNA polymerase II enhancer elements.

Activation of the U2 snRNA promoter by the octamer motif defines a new class of RNA polymerase II enhancer elements.

The highly conserved U small nuclear RNA 3'-end formation signal is quite tolerant to mutation.

Synthesis of U1 RNA in isolated mouse cell nuclei: initiation and 3'-end formation.

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