scholarly journals Interplay between HIV-1 Vpr and Sp1 Modulates p21WAF1Gene Expression in Human Astrocytes

2004 ◽  
Vol 279 (44) ◽  
pp. 46046-46056 ◽  
Author(s):  
Shohreh Amini ◽  
Marcus Saunders ◽  
Kimberly Kelley ◽  
Kamel Khalili ◽  
Bassel E. Sawaya
Keyword(s):  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
Dna Binding ◽  
Zinc Finger ◽  
Human Immunodeficiency Virus Type ◽  
Binding Activity ◽  
Zinc Finger Domain ◽  
Dna Binding Activity ◽  
Immunodeficiency Virus

The Vpr (viral protein R) of human immunodeficiency virus, type 1, which is expressed during the late stage of the viral infection, has received special attention because of its ability to control transcription of the human immunodeficiency virus, type 1, long terminal repeat and to influence cell cycle progression. Here we demonstrate that Vpr has the ability to regulate transcription of the cyclin-dependent kinase inhibitor, p21WAF1(p21), one of the key regulators of the cell cycle, in human astrocytic cells. The results from transcription assays demonstrated that Vpr augments promoter activity of p21 through the GC-rich region located between nucleotides -84 and -74 with respect to the +1 transcription start site. Activation of p21 by Vpr required cooperativity of Sp1, which binds to the DNA sequence spanning -84 to -74. Results from bandshift assay revealed an increased level of Sp1 DNA binding activity in the presence of Vpr. Furthermore, Vpr was able to associate with Sp1 via the zinc finger domain located in the C-terminal region of Sp1. Functional studies revealed that the cooperativity between Vpr and Sp1 requires the zinc finger domain at the C terminus and the glutamine-rich domain at the N terminus of Sp1. Expression of p53 further enhanced the level of Vpr-Sp1-mediated transcription activation of p21 through the sequence spanning -84 to -74 and increased the DNA binding activity of Sp1 in the presence of Vpr. Results from glutathioneS-transferase pull-down assay showed the association of Vpr with p53 in extracts containing Sp1. Altogether, the outcome of our functional and binding studies suggested that the physical interaction of Vpr with Sp1 and p53 could modulate transcriptional activity of p21.

scholarly journals Increased expression and DNA-binding activity of transcription factor Sp1 in doxorubicin-resistant HL-60 leukemia cells.

1990 ◽  
Vol 10 (10) ◽  
pp. 5541-5547 ◽  
Author(s):  
F Borellini ◽  
A Aquino ◽  
S F Josephs ◽  
R I Glazer
Keyword(s):  
Human Immunodeficiency Virus ◽  
Dna Binding ◽  
Dna Binding Proteins ◽  
Binding Activity ◽  
Leukemia Cells ◽  
Nf Kappa B ◽  
Dna Binding Activity ◽  
Nuclear Extracts ◽  
Immunodeficiency Virus

The processes responsible for the multidrug-resistant (Mdr) phenotype in Adriamycin (doxorubicin)-resistant HL-60 leukemia cells (HL-60/AR) are not defined. Since enhanced transcription of resistance-related proteins is associated with Mdr cells, we sought to determine whether changes in the expression of specific transcription factors were a feature characteristic of the Mdr process. Nuclear extracts were prepared from wild-type and resistant cells and compared for their ability to bind DNA consensus sequences for the transcription factors Sp1 and NF kappa B contained in the 5' long terminal repeat region of human immunodeficiency virus type 1. Southwestern (DNA-protein) blots showed a family of DNA-binding proteins of 105 kilodaltons (kDa) that were present only in HL-60/AR cells. Competitive gel shift assays indicated that these factors were related to transcription factor Sp1, and immunoblotting with an Sp1 antibody identified this factor as Sp1. DNase footprinting of the promoter region in the human immunodeficiency virus type 1 5' long terminal repeat showed that protection occurred at two Sp1 sites as well as two NF kappa B sites and the trans-acting region with nuclear extracts only from resistant cells. Preliminary evidence also suggests that phosphorylation may play a negative regulatory role in the activity of Sp1, since calf intestine alkaline phosphatase stimulated the DNA-binding activity of Sp1 in vitro. These results indicate that HL-60/AR cells contain an abundance of DNA-binding proteins, particularly Sp1, which probably interact with other cis-acting regulatory proteins in a cooperative manner.

Increased expression and DNA-binding activity of transcription factor Sp1 in doxorubicin-resistant HL-60 leukemia cells

1990 ◽  
Vol 10 (10) ◽  
pp. 5541-5547
Author(s):  
F Borellini ◽  
A Aquino ◽  
S F Josephs ◽  
R I Glazer
Keyword(s):  
Human Immunodeficiency Virus ◽  
Dna Binding ◽  
Dna Binding Proteins ◽  
Binding Activity ◽  
Leukemia Cells ◽  
Nf Kappa B ◽  
Dna Binding Activity ◽  
Nuclear Extracts ◽  
Immunodeficiency Virus

The processes responsible for the multidrug-resistant (Mdr) phenotype in Adriamycin (doxorubicin)-resistant HL-60 leukemia cells (HL-60/AR) are not defined. Since enhanced transcription of resistance-related proteins is associated with Mdr cells, we sought to determine whether changes in the expression of specific transcription factors were a feature characteristic of the Mdr process. Nuclear extracts were prepared from wild-type and resistant cells and compared for their ability to bind DNA consensus sequences for the transcription factors Sp1 and NF kappa B contained in the 5' long terminal repeat region of human immunodeficiency virus type 1. Southwestern (DNA-protein) blots showed a family of DNA-binding proteins of 105 kilodaltons (kDa) that were present only in HL-60/AR cells. Competitive gel shift assays indicated that these factors were related to transcription factor Sp1, and immunoblotting with an Sp1 antibody identified this factor as Sp1. DNase footprinting of the promoter region in the human immunodeficiency virus type 1 5' long terminal repeat showed that protection occurred at two Sp1 sites as well as two NF kappa B sites and the trans-acting region with nuclear extracts only from resistant cells. Preliminary evidence also suggests that phosphorylation may play a negative regulatory role in the activity of Sp1, since calf intestine alkaline phosphatase stimulated the DNA-binding activity of Sp1 in vitro. These results indicate that HL-60/AR cells contain an abundance of DNA-binding proteins, particularly Sp1, which probably interact with other cis-acting regulatory proteins in a cooperative manner.

Characterization of the DNA Binding Activity of the ZFY Zinc Finger Domain

Biochemistry ◽  
2010 ◽  
Vol 49 (4) ◽  
pp. 679-686 ◽  
Author(s):  
Jennifer Grants ◽  
Erin Flanagan ◽  
Andrea Yee ◽  
Paul J. Romaniuk
Keyword(s):  
Dna Binding ◽  
Zinc Finger ◽  
Binding Activity ◽  
Zinc Finger Domain ◽  
Dna Binding Activity

Human immunodeficiency virus type 1 Tat protein modulates cell cycle and apoptosis in Epstein–Barr virus-immortalized B cells

2004 ◽  
Vol 295 (2) ◽  
pp. 539-548 ◽  
Author(s):  
Eva Colombrino ◽  
Elisabetta Rossi ◽  
Gianna Ballon ◽  
Liliana Terrin ◽  
Stefano Indraccolo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
B Cells ◽  
Human Immunodeficiency Virus Type ◽  
Epstein Barr Virus ◽  
Tat Protein ◽  
Barr Virus ◽  
Immunodeficiency Virus ◽  
Epstein Barr

scholarly journals Human Immunodeficiency Virus Type 1 (HIV-1) Vpr Enhances Expression from Unintegrated HIV-1 DNA

2003 ◽  
Vol 77 (7) ◽  
pp. 3962-3972 ◽  
Author(s):  
Betty Poon ◽  
Irvin S. Y. Chen
Keyword(s):  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
Cell Cycle Arrest ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Viral Dna ◽  
Cycle Arrest ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Retroviral DNA synthesized prior to integration, termed unintegrated viral DNA, is classically believed to be transcriptionally inert and to serve only as a precursor to the transcriptionally active integrated proviral DNA form. However, it has recently been found to be expressed under some circumstances during human immunodeficiency virus type 1 (HIV-1) replication and may play a significant role in HIV-1 pathogenesis. HIV-1 Vpr is a virion-associated accessory protein that is critical for HIV-1 replication in nondividing cells and induces cell cycle arrest and apoptosis. We find that Vpr, either expressed de novo or released from virions following viral entry, is essential for unintegrated viral DNA expression. HIV-1 mutants defective for integration in either the integrase catalytic domain or the cis-acting att sites can express unintegrated viral DNA at levels similar to that of wild-type HIV-1, but only in the presence of Vpr. In the absence of Vpr, the expression of unintegrated viral DNA decreases 10- to 20-fold. Vpr does not affect the efficiency of integration from integrase-defective HIV-1. Vpr-mediated enhancement of expression from integrase-defective HIV-1 requires that the viral DNA be generated in cells through infection and is mediated via a template that declines over time. Vpr activation of expression does not require exclusive nuclear localization of Vpr nor does it correlate with Vpr-mediated cell cycle arrest. These results attribute a new function to HIV-1 Vpr and implicate Vpr as a critical component in expression from unintegrated HIV-1 DNA.

scholarly journals Human Immunodeficiency Virus Type 1 Vpr Induces G2 Checkpoint Activation by Interacting with the Splicing Factor SAP145

2006 ◽  
Vol 26 (21) ◽  
pp. 8149-8158 ◽  
Author(s):  
Yasuhiko Terada ◽  
Yuko Yasuda
Keyword(s):  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
Cell Cycle Arrest ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Splicing Factor ◽  
Checkpoint Activation ◽  
Cycle Arrest ◽  
Immunodeficiency Virus

ABSTRACT Vpr, the viral protein R of human immunodeficiency virus type 1, induces G2 cell cycle arrest and apoptosis in mammalian cells via ATR (for “ataxia-telangiectasia-mediated and Rad3-related”) checkpoint activation. The expression of Vpr induces the formation of the γ-histone 2A variant X (H2AX) and breast cancer susceptibility protein 1 (BRCA1) nuclear foci, and a C-terminal domain is required for Vpr-induced ATR activation and its nuclear localization. However, the cellular target of Vpr, as well as the mechanism of G2 checkpoint activation, was unknown. Here we report that Vpr induces checkpoint activation and G2 arrest by binding to the CUS1 domain of SAP145 and interfering with the functions of the SAP145 and SAP49 proteins, two subunits of the multimeric splicing factor 3b (SF3b). Vpr interacts with and colocalizes with SAP145 through its C-terminal domain in a speckled distribution. The depletion of either SAP145 or SAP49 leads to checkpoint-mediated G2 cell cycle arrest through the induction of nuclear foci containing γ-H2AX and BRCA1. In addition, the expression of Vpr excludes SAP49 from the nuclear speckles and inhibits the formation of the SAP145-SAP49 complex. To conclude, these results point out the unexpected roles of the SAP145-SAP49 splicing factors in cell cycle progression and suggest that cellular expression of Vpr induces checkpoint activation and G2 arrest by interfering with the function of SAP145-SAP49 complex in host cells.

scholarly journals Human Immunodeficiency Virus Type 1 Vpr-Dependent Cell Cycle Arrest through a Mitogen-Activated Protein Kinase Signal Transduction Pathway

2005 ◽  
Vol 79 (17) ◽  
pp. 11366-11381 ◽  
Author(s):  
Naoto Yoshizuka ◽  
Yuko Yoshizuka-Chadani ◽  
Vyjayanthi Krishnan ◽  
Steven L. Zeichner
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Human Immunodeficiency Virus ◽  
Cell Cycle Arrest ◽  
Host Cell ◽  
Human Immunodeficiency Virus Type ◽  
Erk Pathway ◽  
Cycle Arrest ◽  
Immunodeficiency Virus

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) Vpr protein has important functions in advancing HIV pathogenesis via several effects on the host cell. Vpr mediates nuclear import of the preintegration complex, induces host cell apoptosis, and inhibits cell cycle progression at G2, which increases HIV gene expression. Some of Vpr's activities have been well described, but some functions, such as cell cycle arrest, are not yet completely characterized, although components of the ATR DNA damage repair pathway and the Cdc25C and Cdc2 cell cycle control mechanisms clearly play important roles. We investigated the mechanisms underlying Vpr-mediated cell cycle arrest by examining global cellular gene expression profiles in cell lines that inducibly express wild-type and mutant Vpr proteins. We found that Vpr expression is associated with the down-regulation of genes in the MEK2-ERK pathway and with decreased phosphorylation of the MEK2 effector protein ERK. Exogenous provision of excess MEK2 reverses the cell cycle arrest associated with Vpr, confirming the involvement of the MEK2-ERK pathway in Vpr-mediated cell cycle arrest. Vpr therefore appears to arrest the cell cycle at G2/M through two different mechanisms, the ATR mechanism and a newly described MEK2 mechanism. This redundancy suggests that Vpr-mediated cell cycle arrest is important for HIV replication and pathogenesis. Our findings additionally reinforce the idea that HIV can optimize the host cell environment for viral replication.

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