Activation of the human immunodeficiency virus long terminal repeat by herpes simplex virus type 1 is associated with induction of a nuclear factor that binds to the NF-kappa B/core enhancer sequence.

It has been previously shown that herpes simplex virus type 1 (HSV-1) infection of HeLa cells results in augmentation of gene expression directed by the human immunodeficiency virus (HIV) long terminal repeat (LTR). This effect is presumably mediated by protein interactions with the LTR. We have used two different assays of DNA-protein interactions to study the HSV-induced activation of the HIV LTR. Activation of the HIV LTR is associated with increased protein binding to LTR sequences in a region including the NF-kappa B/core enhancer and the Sp1 binding sequences as monitored by an exonuclease protection assay. Gel retardation assays demonstrated that HSV-1 infection resulted in the induction of a nuclear factor(s) that binds to the NF-kappa B/core enhancer sequence. In addition to the activation of the HIV LTR, HSV induction of NF-kappa B activity may be important for the regulation of HSV gene expression during a herpesvirus infection.     

A human nuclear shuttling protein that interacts with human immunodeficiency virus type 1 matrix is packaged into virions

Active nuclear import of the human immunodeficiency virus type 1 (HIV-1) preintegration complex (PIC) is essential for the productive infection of nondividing cells. Nuclear import of the PIC is mediated by the HIV-1 matrix protein, which also plays several critical roles during viral entry and possibly during virion production facilitating the export of Pr55(Gag) and genomic RNA. Using a yeast two-hybrid screen, we identified a novel human virion-associated matrix-interacting protein (VAN) that is highly conserved in vertebrates and expressed in most human tissues. Its expression is upregulated upon activation of CD4(+) T cells. VAN is efficiently incorporated into HIV-1 virions and, like matrix, shuttles between the nucleus and cytoplasm. Furthermore, overexpression of VAN significantly inhibits HIV-1 replication in tissue culture. We propose that VAN regulates matrix nuclear localization and, by extension, both nuclear import of the PIC and export of Pr55(Gag) and viral genomic RNA during virion production. Our data suggest that this regulatory mechanism reflects a more global process for regulation of nucleocytoplasmic transport.     

Herpes simplex virus type 1-mediated induction of human immunodeficiency virus type 1 provirus correlates with binding of nuclear proteins to the NF-kappa B enhancer and leader sequence.

Herpes simplex virus type 1 (HSV-1) infection induces expression of the human immunodeficiency virus type 1 (HIV-1) provirus in the chronically infected T-cell line ACH-2. The HSV-1-mediated induction correlates with the appearance of two NF-kappa B-specific proteins of 55 and 85 kDa in the nucleus and with the binding of 50-kDa nuclear protein to the LBP-1 binding site of the untranslated leader sequence of the HIV-1 long terminal repeat. The HSV-1-induced LBP-1 binding protein, designated HLP-1, is present exclusively in HSV-1-infected, but not in phorbol-12-myristate-13-acetate- or tumor necrosis factor alpha-treated ACH-2 cells. Both the NF-kappa B and LBP-1 target sequences, when inserted either alone or together 5' of a heterologous minimal promoter (thymidine kinase), confer inducibility by HSV-1 infection in a transient transfection assay. Thus, it appears that the HSV-1-mediated activation of HIV-1 provirus is brought about by the binding of both NF-kappa B and HLP-1 specific proteins to two distinct regions of HIV-1 long terminal repeat.     

Cell-specific differences in activation of NF-kappa B regulatory elements of human immunodeficiency virus and beta interferon promoters by tumor necrosis factor.

Three aspects of the involvement of tumor necrosis factor in human immunodeficiency virus (HIV) pathogenesis were examined. Tumor necrosis factor alpha (TNF-alpha) mRNA production was analyzed by polymerase chain reaction amplification in monocytic U937 cells and in a chronically HIV infected U937 cell line (U9-IIIB). TNF-alpha RNA was undetectable in U937 cells, whereas a low constitutive level was detected in U9-IIIB cells. Paramyxovirus infection induced a 5- to 10-fold increase in the steady-state level of TNF-alpha RNA in U9-IIIB cells compared with U937 cells, suggesting that HIV-infected monocytic cells produced higher levels of TNF-alpha than did normal cells after a secondary virus infection. The effects of TNF-alpha on gene expression were examined by transient expression assays using reporter chloramphenicol acetyltransferase plasmids linked to regulatory elements from the HIV long terminal repeat (LTR) and the beta interferon promoter. In U937 and Jurkat T lymphoid cells, the inducibility of the different hybrid promoters by TNF-alpha or phorbol ester varied in a cell type- and promoter context-specific manner; the levels of gene activity of NF-kappa B-containing plasmids correlated directly with induction of NF-kappa B DNA-binding activity. Although the intact beta interferon promoter was only weakly stimulated by phorbol ester or TNF-alpha, multimers of the PRDII NF-kappa B-binding domain were inducible by both agents. TNF-alpha was able to increase expression of the HIV LTR in T cells, but in monocytic cells, TNF-alpha did not induce the HIV LTR above a constitutive level of activity. This level of NF-kappa B-independent activity appears to be sufficient for virus multiplication, since TNF-alpha treatment had no effect on the kinetics of de novo HIV type 1 (HIV-1) infection and viral RNA production in U937 cells. However, in Jurkat cells, TNF-alpha dramatically enhanced the spread of HIV-1 through the cell population and increased viral RNA synthesis, indicating that in T cells HIV-1 multiplication was stimulated by TNF-alpha treatment.     

Activation of interleukin-6 gene expression through the NF-kappa B transcription factor.

The promoter region of the interleukin-6 (IL-6) gene has a putative NF-kappa B-binding site. We found that a fragment of the IL-6 promoter containing the site specifically binds highly purified NF-kappa B protein and the NF-kappa B protein in nuclear extracts of phorbol ester-induced Jurkat cells. Mutations of the NF-kappa B site abolished complex formation with both purified NF-kappa B and the nuclear extract protein. Transient expression of chloramphenicol acetyltransferase (CAT) plasmids containing the IL-6 promoter revealed very little activity of the promoter in U-937 monocytic cells and in HeLa cells before stimulation. However, stimulation of U-937 and HeLa cells by inducers of NF-kappa B led to a dramatic increase in CAT activity. Mutations in the NF-kappa B-binding site abolished inducibility of IL-6 promoter-cat constructs in U-937 cells by lipopolysaccharide, tumor necrosis factor alpha, the double-stranded RNA poly(IC), or phytohemagglutinin and in HeLa cells by tumor necrosis factor alpha and drastically reduced but did not completely eliminate inducibility in HeLa cells stimulated by double-stranded RNA poly(IC) or phorbol 12-myristate 13-acetate. These results suggest that NF-kappa B is an important mediator for activation of the IL-6 gene by a variety of IL-6 inducers in both U-937 and HeLa cells and that alternative inducible enhancer elements contribute in a cell-specific manner to IL-6 gene induction. Because NF-kappa B is involved in the control of a variety of genes activated upon inflammation, NF-kappa B may play a central role in the inflammatory response to infection and tissue injury.