Effect of the Position of TAR on Transcriptional Activation by HIV-1 Tatin Vivo

Wright, Stephanie C.; Luccarini, Craig

doi:10.1006/jmbi.1996.0551

Cited by 4 publications

(5 citation statements)

References 28 publications

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“…The pCM/IVLuc contained the TAR sequence and was Tat-inducible although less efficiently than the parental HIV LTR (Table I, middle). The latter result confirmed a previous observation establishing that the TAR sequences remain functional within heterologous promoters (49). The pCM/IVLuc was actinomycin-inducible but with a lower efficiency than the parental pHIVLucA41 confirming that sequences downstream from the TATA box, overlapping the TAR element, contribute to the response.…”

Section: Dna Sequences Upstream and Downstream From The Tata Box Confsupporting

confidence: 89%

The Transcriptional Inhibitors, Actinomycin D and α-Amanitin, Activate the HIV-1 Promoter and Favor Phosphorylation of the RNA Polymerase II C-terminal Domain

Cassé¹,

Giannoni²,

Nguyen

et al. 1999

Journal of Biological Chemistry

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II) 1 (1, 2) and RNAP III (3), with RNAP II being the most sensitive. As a consequence, the incorporation of new ribonucleotides into the nascent RNA chains is blocked (4). Actinomycin D is generally thought to intercalate into DNA thereby preventing the progression of RNA polymerases, with RNAP I being the most sensitive (5, 6). In previous work, we have shown that the average phosphorylation of RNAP II C-terminal domain (CTD) increases in cells exposed to actinomycin D (7, 8). The activity of RNAP II is regulated by multisite phosphorylation on the CTD (9). The underphosphorylated CTD mediates multiple protein-protein interactions involved in the assembly of a preinitiation complex. The subsequent phosphorylation of the CTD occurs along the initiation of transcription and contributes to disrupt some of the interactions that lead to the assembly of the preinitiation complex on promoters. Phosphorylation of RNAP II at this step is required to elongate transcription and mediates the recruitment of various enzymatic complexes involved in processing of the primary transcript (10 -12). In contrast, phosphorylation of the CTD prior to the formation of the preinitiation complex represses the expression of specific genes (13). Hence, the increase in average phosphorylation of the CTD promoted by actinomycin D raises the possibility that different genes may have different susceptibilities to this drug.Several cyclin-dependent kinases (CDK) have been shown to phosphorylate the CTD and regulate transcription. CDK7, and its partner, cyclin H, are subunits of the general transcription factor, TFIIH, a component of the preinitiation complex (14, 15); CDK8 and its partner cyclin C belong to the RNAP II holoenzyme (16, 17); CDK9/PITALRE, and its partners, cyclins T1 and T2, are subunits of the transcription elongation factor P-TEFb (18). 5,6-Dichloro-1-␤-D-ribofuranosylbenzimidazole (DRB) is another widely used transcriptional inhibitor (19) that inhibits CDK7 (20) and CDK9/PITALRE (21). The average CTD phosphorylation is decreased in cells exposed to DRB (7), suggesting that these kinases might contribute to global CTD phosphorylation in vivo.

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Section: Dna Sequences Upstream and Downstream From The Tata Box Confsupporting

confidence: 89%

The Transcriptional Inhibitors, Actinomycin D and α-Amanitin, Activate the HIV-1 Promoter and Favor Phosphorylation of the RNA Polymerase II C-terminal Domain

Cassé¹,

Giannoni²,

Nguyen

et al. 1999

Journal of Biological Chemistry

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“…3,38 On the other hand, there is evidence that the TAR region of HIV-1 can be functional when displaced downstream of the start of transcription. [17][18][19] In these studies, TAR was separated from the transcription initiation site from 25 bp up to O500 bp without substantial effects on Tat-dependent transcription. Moreover, Selby et al showed a sequential decrease of Tat-dependent transcription with increasing length of the inserted sequences (ranging from 11 bp to 88 bp), but even the longest insertion retained about 20% of Tat-dependent activity.…”

Section: Discussionmentioning

confidence: 99%

“…3,38 Others described constructs with insertions between 25 bp up to some 500 bp that showed no defects in Tat-dependent transcription at all. [17][18][19] Hence we reasoned that spacing constraints alone are likely not sufficient to explain the essentially complete unresponsiveness of the SIVmac239-EF1a/STR mutant to Tat and thus explored the possibility that structural alterations also may have occurred. To this end, we performed a RNA secondary structure prediction analysis using the MFOLD 3.0 software †.…”

Section: Revertant Viruses With Minimal Promoter Sequences Efficientlmentioning

confidence: 98%

“…3,16 More recently, however, it was demonstrated that TAR can mediate Tat-activated transcription over long distances. [17][18][19] This implied that Tat is introduced into transcription complexes during their transit through TAR, thus initiating their transformation into effective, elongation competent forms. Furthermore this implied that Tat-mediated transactivation would depend on the processivity of transcription from a given upstream promoter in the absence of Tat.…”

Section: Introductionmentioning

confidence: 98%

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Anti-termination by SIV Tat Requires Flexibility of the Nascent TAR Structure

Sommer

Vartanian

Wachsmuth

et al. 2004

Journal of Molecular Biology

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“…In the cell‐free systems, the total level of initiation remains constant in the presence or absence of Tat, but addition of Tat produces a dramatic increase in the amount of longer transcripts (Marciniak and Sharp, 1991; Kato et al ., 1992; Graeble et al ., 1993; Laspia et al ., 1993; Rittner et al ., 1995). Further evidence that Tat activation of RNA polymerase processivity is a post‐initiation event stems from the observation that TAR RNA elements are functional even when they are placed several hundred nucleotides downstream of the start of transcription (Churcher et al ., 1995; Wright and Luccarini, 1996).…”

Section: Introductionmentioning

confidence: 99%

Transfer of Tat and release of TAR RNA during the activation of the human immunodeficiency virus type-1 transcription elongation complex

Keen¹

1997

The EMBO Journal

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of cellular factors including TFIIS (Reines et al., 1989; Cheshire SK10 4TG, UK Christie et al., 1994; Cipres-Palacin and Kane, 1994), 2 Corresponding author TFIIF (Tan et al., 1995) and elongin (Aso et al., 1995;Kibel et al., 1995;Pause et al., 1996) can modify RNA The HIV-1 trans-activator protein, Tat, is a potent polymerase II elongation rates. Transcription elongation activator of transcriptional elongation. Tat is recruited and promoter clearance are also regulated by phosphorylto the elongating RNA polymerase during its transit ation of the carboxy-terminal domain (CTD) of RNA through the trans-activation response region (TAR) polymerase II by TFIIH (Laybourn and Dahmus, 1990; because of its ability to bind directly to TAR RNA O'Brien et al., 1994; Yankulov et al., 1995), and several expressed on the nascent RNA chain. We have shown other kinases including the P-TEFb elongation factor that transcription complexes that have acquired Tat (Marshall et al., 1996). However, each of these factors produce 3-fold more full-length transcripts than comappears to be part of the basic transcription machinery, plexes not exposed to Tat. Western blotting experiments and the biochemical basis for gene-specific control of demonstrated that Tat is tightly associated with the elongation has not been discovered. paused polymerases. To determine whether TAR RNA The human immunodeficiency virus (HIV) trans-activalso becomes attached to the transcription complex, ator protein (Tat) is the first example of a viral regulatory DNA oligonucleotides were annealed to the nascent protein that controls elongation by RNA polymerase II chains on the arrested complexes and the RNA was (Kao et al., 1987;Laspia et al., 1989; Ratnasabapathy cleaved by RNase H. After cleavage, the 5Ј end of the et al., 1990). In the absence of Tat, the majority of RNA nascent chain, carrying TAR RNA, is quantitatively polymerases initiating transcription stall near the promoter. removed, but the 3Ј end of the transcript remainsFollowing the addition of Tat, there is a dramatic increase associated with the transcription complex. Even after in the density of RNA polymerases found downstream of the removal of TAR RNA, transcription complexes the promoter (Kao et al., 1987;Laspia et al., 1989 Laspia et al., , 1990; that have been activated by Tat show enhanced pro- Feinberg et al., 1991;Marciniak and Sharp, 1991; Kato cessivity. We conclude that Tat, together with cellular et al., 1992; Rittner et al., 1995). co-factors, becomes attached to the transcription comTat activity requires the trans-activator response element plex and stimulates processivity, whereas TAR RNA (TAR), an RNA element located at the 5Ј end of the does not play a direct role in the activation of elongation nascent transcript which forms a stem-loop structure of and is used simply to recruit Tat and cellular co-factors. 59 nucleotides (Rosen et al., 1985; Cullen, 1986;Muesing

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Effect of the Position of TAR on Transcriptional Activation by HIV-1 Tatin Vivo

Cited by 4 publications

References 28 publications

The Transcriptional Inhibitors, Actinomycin D and α-Amanitin, Activate the HIV-1 Promoter and Favor Phosphorylation of the RNA Polymerase II C-terminal Domain

The Transcriptional Inhibitors, Actinomycin D and α-Amanitin, Activate the HIV-1 Promoter and Favor Phosphorylation of the RNA Polymerase II C-terminal Domain

Anti-termination by SIV Tat Requires Flexibility of the Nascent TAR Structure

Transfer of Tat and release of TAR RNA during the activation of the human immunodeficiency virus type-1 transcription elongation complex

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