Transcriptional Regulation of the TATA-Binding Protein by Ras Cellular Signaling

ABSTRACT Our previous studies have demonstrated that the level of the central transcription factor TATA-binding protein (TBP) is increased in cells expressing the hepatitis B virus (HBV) X protein through the activation of the Ras signaling pathway, which serves to enhance both RNA polymerase I and III promoter activities. To understand the mechanism by which TBP is regulated, we have investigated whether enhanced expression is modulated at the transcriptional level. Nuclear run-on assays revealed that the HBV X protein increases the number of active transcription complexes on the TBP gene. In transient-transfection assays with both transformed and primary hepatocytes, the human TBP promoter was shown to be induced by expression of the HBV X protein in a Ras-dependent manner, requiring both Ral guanine nucleotide dissociation stimulator (RalGDS) and Raf signaling. Transient overexpression of TBP did not affect TBP promoter activity. To further delineate the downstream Ras-mediated events contributing to TBP promoter regulation in primary rat hepatocytes, the best-characterized Ras effectors, Raf, phosphoinositide 3-kinase (PI-3 kinase), and RalGDS, were examined. Activation of either Raf or RalGDS, but not that of PI-3 kinase, was sufficient to induce TBP promoter activity. Both Raf- and RalGDS-mediated induction required the activation of mitogen-activated protein kinase kinase (MEK). In addition, another distinct Ras-activated pathway, which does not require MEK activation, appears to induce TBP promoter activity. Analysis of the DNA sequence requirement within the TBP promoter responsible for these regulatory events defined three distinct regions that modulate the abilities of Raf, RalGDS, and the Ras-dependent, MEK-independent pathways to regulate human TBP promoter activity. Together, these results provide new evidence that TBP can be regulated at the transcriptional level and identify three distinct Ras-activated pathways that modulate this central eukaryotic transcription factor.

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Immunopurification of yeast TATA-binding protein and associated factors. Presence of transcription factor IIIB transcriptional activity

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)82256-6 ◽

1993 ◽

Vol 268 (21) ◽

pp. 15325-15328

Author(s):

D. Poon ◽

P.A. Weil

Keyword(s):

Transcription Factor ◽

Associated Factors ◽

Transcriptional Activity ◽

Binding Protein ◽

Tata Binding Protein ◽

Transcription Factor Iiib

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Transcription factor (TF) IIB and TFIIA can independently increase the affinity of the TATA-binding protein for DNA.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)37190-9 ◽

1994 ◽

Vol 269 (11) ◽

pp. 8280-8286

Author(s):

A.N. Imbalzano ◽

K.S. Zaret ◽

R.E. Kingston

Keyword(s):

Transcription Factor ◽

Binding Protein ◽

Tata Binding Protein

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The Human Transcription Factor IID Subunit Human TATA-binding Protein-associated Factor 28 Interacts in a Ligand-reversible Manner with the Vitamin D3and Thyroid Hormone Receptors

Journal of Biological Chemistry ◽

10.1074/jbc.275.14.10064 ◽

2000 ◽

Vol 275 (14) ◽

pp. 10064-10071 ◽

Cited By ~ 17

Author(s):

Gabrielle Mengus ◽

Yann-Gaël Gangloff ◽

Lucie Carré ◽

Anne-Claire Lavigne ◽

Irwin Davidson ◽

...

Keyword(s):

Transcription Factor ◽

Thyroid Hormone ◽

Hormone Receptors ◽

Binding Protein ◽

Tata Binding Protein ◽

Thyroid Hormone Receptors ◽

Associated Factor ◽

Transcription Factor Iid ◽

Human Transcription Factor

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RMP, a Novel RNA Polymerase II Subunit 5-Interacting Protein, Counteracts Transactivation by Hepatitis B Virus X Protein

Molecular and Cellular Biology ◽

10.1128/mcb.18.12.7546 ◽

1998 ◽

Vol 18 (12) ◽

pp. 7546-7555 ◽

Cited By ~ 65

Author(s):

Dorjbal Dorjsuren ◽

Yong Lin ◽

Wenxiang Wei ◽

Tatsuya Yamashita ◽

Takahiro Nomura ◽

...

Keyword(s):

Hepatitis B Virus ◽

Hepatitis B ◽

Rna Polymerase ◽

Rna Polymerase Ii ◽

Binding Protein ◽

Host Protein ◽

Dependent Manner ◽

Binding Region ◽

X Protein ◽

B Virus

ABSTRACT To modulate transcription, regulatory factors communicate with basal transcription factors and/or RNA polymerases in a variety of ways. Previously, it has been reported that RNA polymerase II subunit 5 (RPB5) is one of the targets of hepatitis B virus X protein (HBx) and that both HBx and RPB5 specifically interact with general transcription factor IIB (TFIIB), implying that RPB5 is one of the communicating subunits of RNA polymerase II involved in transcriptional regulation. In this context, we screened for a host protein(s) that interacts with RPB5. By far-Western blot screening, we cloned a novel gene encoding a 508-amino-acid-residue RPB5-binding protein from a HepG2 cDNA library and designated it RPB5-mediating protein (RMP). Expression of RMP mRNA was detected ubiquitously in various tissues. Bacterially expressed recombinant RMP strongly bound RPB5 but neither HBx nor TATA-binding protein in vitro. Endogenous RMP was immunologically detected interacting with assembled RPB5 in RNA polymerase in mammalian cells. The central part of RMP is responsible for RPB5 binding, and the RMP-binding region covers both the TFIIB- and HBx-binding sites of RPB5. Overexpression of RMP, but not mutant RMP lacking the RPB5-binding region, inhibited HBx transactivation of reporters with different HBx-responsive cis elements in transiently transfected cells. The repression by RMP was counteracted by HBx in a dose-dependent manner. Furthermore, RMP has an inhibitory effect on transcriptional activation by VP16 in the absence of HBx. These results suggest that RMP negatively modulates RNA polymerase II function by binding to RPB5 and that HBx counteracts the negative role of RMP on transcription indirectly by interacting with RPB5.

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Adeno-Associated Virus Major Rep78 Protein Disrupts Binding of TATA-Binding Protein to the p97 Promoter of Human Papillomavirus Type 16

Journal of Virology ◽

10.1128/jvi.74.5.2459-2465.2000 ◽

2000 ◽

Vol 74 (5) ◽

pp. 2459-2465 ◽

Cited By ~ 17

Author(s):

Pei-Fen Su ◽

Shu-Yuan Chiang ◽

Cheng-Wen Wu ◽

Felicia Y.-H. Wu

Keyword(s):

Human Papillomavirus ◽

Binding Protein ◽

Core Promoter ◽

Tata Binding Protein ◽

Tata Box ◽

Dependent Manner ◽

Hpv 16 ◽

Adeno Associated Virus ◽

Human Papillomavirus Type 16 ◽

E6 And E7

ABSTRACT Adeno-associated virus type 2 (AAV) is known to inhibit the promoter activities of several oncogenes and viral genes, including the human papillomavirus type 16 (HPV-16) E6 and E7 transforming genes. However, the target elements of AAV on the long control region (LCR) upstream of E6 and E7 oncogenes are elusive. A chloramphenicol acetyltransferase assay was performed to study the effect of AAV on the transcription activity of the HPV-16 LCR in SiHa (HPV-positive) and C-33A (HPV-negative) cells. The results reveal that (i) AAV inhibited HPV-16 LCR activity in a dose-dependent manner, (ii) AAV-mediated inhibition did not require the HPV gene products, and (iii) the AAV replication gene product Rep78 was involved in the inhibition. Deletion mutation analyses of the HPV-16 LCR showed that regulatory elements outside the core promoter region of the LCR may not be direct targets of AAV-mediated inhibition. Further study with the electrophoretic mobility shift assay demonstrated that Rep78 interfered with the binding of TATA-binding protein (TBP) to the TATA box of the p97 core promoter more significantly than it disrupted the preformed TBP-TATA complex. These data thus suggest that Rep78 may inhibit transcription initiation of the HPV-16 LCR by disrupting the interaction between TBP and the TATA box of the p97 core promoter.

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