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G J Nabel

Publications and source records attributed to G J Nabel.

At least 127 records · Page 7Linked to original sources
PubMed1994

Transcription factor AP-2 regulates human immunodeficiency virus type 1 gene expression.

Human immunodeficiency virus type 1 (HIV-1) gene expression is regulated by an enhancer region composed of multiple potential cis-acting regulatory sites. Here, we describe binding sites for the transcription factor AP-2 in the HIV-1 long terminal repeat which modulate HIV enhancer function. One site is embedded within the two previously described kappa B elements, and a second site is detected further downstream. DNase I footprinting and electrophoretic mobility shift assay experiments demonstrated that AP-2 binds to the site between the kappa B elements. Interestingly, AP-2 and NF-kappa B bind to this region in a mutually exclusive manner. Mutations which disrupt this AP-2-binding site lower basal levels of transcription but do not affect NF-kappa B-mediated induction by tumor necrosis factor alpha in Jurkat T leukemia cells.

Base Sequence↗
PubMed1994

An interaction between the DNA-binding domains of RelA(p65) and Sp1 mediates human immunodeficiency virus gene activation.

Induction of human immunodeficiency virus type 1 (HIV-1) gene expression in stimulated T cells has been attributed to the activation of the transcription factor NF-kappa B. The twice-repeated kappa B sites within the HIV-1 long terminal repeat are in close proximity to three binding sites for Sp1. We have previously shown that a cooperative interaction of NF-kappa B with Sp1 is required for the efficient stimulation of HIV-1 transcription. In this report, we define the domains of each protein responsible for this effect. Although the transactivation domains seemed likely to mediate this interaction, we find, surprisingly, that this interaction occurs through the putative DNA-binding domains of both proteins. Sp1 specifically interacted with the amino-terminal region of RelA(p65). Similarly, RelA bound directly to the zinc finger region of Sp1. This interaction was specific and resulted in cooperative DNA binding to the kappa B and Sp1 sites in the HIV-1 long terminal repeat. Furthermore, the amino-terminal region of RelA did not associate with several other transcription factors, including MyoD, E12, or Kox15, another zinc finger protein. These findings suggest that the juxtaposition of DNA-binding sites promotes a specific protein interaction between the DNA-binding regions of these transcription factors. This interaction is required for HIV transcriptional activation and may provide a mechanism to allow for selective activation of kappa B-regulated genes.

Animals↗
PubMed1994

Transcriptional regulation of NF-kappa B2: evidence for kappa B-mediated positive and negative autoregulation.

NF-kappa B is an inducible transcription factor complex which regulates the expression of a variety of genes which are involved in the immune, inflammatory, and acute-phase responses. The maintenance of NF-kappa B activity in stimulated cells requires ongoing protein synthesis, suggesting several modes of regulation. In this report, we have characterized the transcriptional regulation of one family member, NF-kappa B2. The genomic structure and sequence of NF-kappa B2 revealed the presence of two promoters and at least four kappa B regulatory elements, which mediate responsiveness to phorbol myristate acetate and tumor necrosis factor alpha. Similar to other NF-kappa B family members, NF-kappa B2 is positively autoregulated. In contrast to other family members, we find that kappa B elements in the NFKB2 promoter can also mediate transcriptional repression in the absence of NF-kappa B. We identified a nuclear complex which binds specifically to a subset of kappa B-related sites but not to the canonical kappa B element. Because of its putative inhibitory or repressive effect, this binding activity has been termed Rep-kappa B. This mechanism of repressing basal NF-kappa B2 transcription in an inactivated state enables the cell to tightly control NF-kappa B2 activity. These data demonstrate that a novel mode of kappa B-dependent regulation is mediated by specific kappa B sites in the NFKB2 promoter.

Base Sequence↗
PubMed1994

Catheter-mediated pulmonary vascular gene transfer and expression.

The study and treatment of pulmonary diseases may be greatly facilitated by in vivo expression of specific recombinant genes in the pulmonary vasculature and lung parenchyma. To evaluate the feasibility of gene transfer to the pulmonary vasculature, cationic liposomes and adenoviral vectors encoding a human placental alkaline phosphatase (hpAP) gene were delivered into a pulmonary artery of 24 pigs by percutaneous right heart catheterization. Pulmonary tissue was harvested within 20 minutes or 5, 14, or 28 days later and was analyzed for gene transfer and expression. Five days after exposure to liposomes or adenoviral vectors, transfer of DNA and expression of mRNA were demonstrated in transfected lung tissue. Recombinant alkaline phosphatase protein was observed in both the vasculature and in alveolar septa but not in the bronchi. Expression of hpAP protein was observed at 5 days, was diminished at 14 days, and was absent 28 days after gene transfer with both liposome and adenoviral vectors. No major adverse effects of gene expression were detected by histological examination of the transfected lung segments compared with control segments. Gene transfer to the lung by either vector was not associated with significant biochemical abnormalities or histological changes 5, 14, or 28 days later in other organs, including carotid artery, heart, liver, spleen, kidney, skeletal muscle, ovary, and testes. These studies demonstrate that after intravascular gene delivery to the lung, recombinant genes are expressed in the vasculature and alveoli. This approach may provide a useful model for the experimental study of pulmonary vascular diseases, including pulmonary fibrosis and pulmonary thrombosis disorders.

Adenoviridae↗
PubMed1994

Regulated expression of a dominant negative form of Rev improves resistance to HIV replication in T cells.

Infection by the human immunodeficiency virus (HIV) has remained refractory to treatment, and molecular genetic interventions have been developed for the treatment of the acquired immunodeficiency syndrome (AIDS). Previous studies have focused on the development of gene products which inhibit productive HIV replication, including transdominant proteins, RNA decoys and ribozymes. In this report, we show that appropriate expression vectors which optimize production and regulated synthesis of a transdominant mutant form of Rev improve its antiviral effect. The combination of a strong constitutive enhancer, a Tat activation response (TAR) regulatory element and transdominant Rev take advantage of three aspects of early viral gene expression to confer increased resistance to HIV replication. This vector may be useful, alone or in combination with other antiviral genes, to provide gene therapy for AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Direct gene transfer with DNA-liposome complexes in melanoma: expression, biologic activity, and lack of toxicity in humans.

Direct gene transfer offers the potential to introduce DNA encoding therapeutic proteins to treat human disease. Previously, gene transfer in humans has been achieved by a cell-mediated ex vivo approach in which cells from the blood or tissue of patients are genetically modified in the laboratory and subsequently returned to the patient. To determine the feasibility and safety of directly transferring genes into humans, a clinical study was performed. The gene encoding a foreign major histocompatibility complex protein, HLA-B7, was introduced into HLA-B7-negative patients with advanced melanoma by injection of DNA-liposome complexes in an effort to demonstrate gene transfer, document recombinant gene expression, and determine the safety and potential toxicity of this therapy. Six courses of treatment were completed without complications in five HLA-B7-negative patients with stage IV melanoma. Plasmid DNA was detected within biopsies of treated tumor nodules 3-7 days after injection but was not found in the serum at any time by using the polymerase chain reaction. Recombinant HLA-B7 protein was demonstrated in tumor biopsy tissue in all five patients by immunochemistry, and immune responses to HLA-B7 and autologous tumors could be detected. No antibodies to DNA were detected in any patient. One patient demonstrated regression of injected nodules on two independent treatments, which was accompanied by regression at distant sites. These studies demonstrate the feasibility, safety, and therapeutic potential of direct gene transfer in humans.

Aged↗
PubMed1993

Purification of the major histocompatibility complex class I transcription factor H2TF1. The full-length product of the nfkb2 gene.

H2TF1 is a ubiquitous major histocompatibility complex (MHC) class I-specific transcription factor, which binds to the palindromic kappa B enhancer site upstream of MHC class I genes. Here we report that H2TF1 consists of a polypeptide with relative molecular mass 110,000, that corresponds to the predicted 100-kDa product (NF-kappa B2 p100) encoded by the candidate proto-oncogene nfkb2 (lyt-10). H2TF1 was purified by a novel affinity chromatography method and identified as the NF-kappa B2 p100 polypeptide by peptide sequencing as well as by reactivity with a specific antiserum. Purified H2TF1 binds the MHC kappa B site with high affinity (KD = 3 x 10(-11) M), in contrast with previous reports that NF-kappa B2 p100 did not bind DNA.

Amino Acid Sequence↗
PubMed1993

Immunotherapy of malignancy by in vivo gene transfer into tumors.

The immune system confers protection against a variety of pathogens and contributes to the surveillance and destruction of neoplastic cells. Several cell types participate in the recognition and lysis of tumors, and appropriate immune stimulation provides therapeutic effects in malignancy. Foreign major histocompatibility complex (MHC) proteins also serve as a potent stimulus to the immune system. In this report, a foreign MHC gene was introduced directly into malignant tumors in vivo in an effort to stimulate tumor rejection. In contrast to previous attempts to induce tumor immunity by cell-mediated gene transfer, the recombinant gene was introduced directly into tumors in vivo. Expression of the murine class I H-2Ks gene within the CT26 mouse colon adenocarcinoma (H-2Kd) or the MCA 106 fibrosarcoma (H-2Kb) induced a cytotoxic T-cell response to H-2Ks and, more importantly, to other antigens present on unmodified tumor cells. This immune response attenuated tumor growth and caused complete tumor regression in many cases. Direct gene transfer in vivo can therefore induce cell-mediated immunity against specific gene products, which provides an immunotherapeutic effect for malignancy, and potentially can be applied to the treatment of cancer and infectious diseases in man.

Animals↗
PubMed1993

Recombinant fibroblast growth factor-1 promotes intimal hyperplasia and angiogenesis in arteries in vivo.

The prototype members of the heparin-binding fibroblast growth factor (FGF) family, acidic FGF (FGF-1) and basic FGF (FGF-2), are among the growth factors that act directly on vascular cells to induce endothelial cell growth and angiogenesis. In vivo, the role of the FGF prototypes in vascular pathology has been difficult to determine. We report here the introduction, by direct gene transfer into porcine arteries, of a eukaryotic expression vector encoding a secreted form of FGF-1. This somatic transgenic model defines gene function in the arterial wall in vivo. FGF-1 expression induced intimal thickening in porcine arteries 21 days after gene transfer, in contrast to control arteries transduced with an Escherichia coli beta-galactosidase gene. Where there was substantial intimal hyperplasia, neocapillary formation was detected in the expanded intima. These findings suggest that FGF-1 induces intimal hyperplasia in the arterial wall in vivo and, through its ability to stimulate angiogenesis in the neointima, FGF-1 could stimulate neovascularization of atherosclerotic plaques. Potentially, gene transfer of FGF-1 could also be used as a genetic intervention to improve blood flow to ischaemic tissues in selected clinical settings.

Animals↗
PubMed1993

A cooperative interaction between NF-kappa B and Sp1 is required for HIV-1 enhancer activation.

The human immunodeficiency virus (HIV-1) long terminal repeat (LTR) contains two binding sites for NF-kappa B in close proximity to three binding sites for the constitutive transcription factor, Sp1. Previously, stimulation of the HIV enhancer in response to mitogens has been attributed to the binding of NF-kappa B to the viral enhancer. In this report, we show that the binding of NF-kappa B is not by itself sufficient to induce HIV gene expression. Instead, a protein-protein interaction must occur between NF-kappa B and Sp1 bound to an adjacent site. Cooperativity both in DNA binding and in transcriptional activation of NF-kappa B and Sp1 was confirmed by electrophoretic mobility shift gel analysis, DNase footprinting, chemical cross-linking and transfection studies in vivo. With a heterologous promoter, we find that the interaction of NF-kappa B with Sp1 is dependent on orientation and position, and is not observed with other elements, including GATA, CCAAT or octamer. An increase in the spacing between the kappa B and Sp1 elements virtually abolishes this functional interaction, which is not restored when these sites are brought back into the same helical position. Several other promoters regulated by NF-kappa B also contain kappa B in proximity to Sp1 binding sites. These findings suggest that an interaction between NF-kappa B and Sp1 is required for inducible HIV-1 gene expression and may serve as a regulatory mechanism to activate specific viral and cellular genes.

Avian Sarcoma Viruses↗
PubMed1993

Tumor necrosis factor receptor expression and signal transduction in HIV-1-infected cells.

OBJECTIVE: To examine the inter-relationship between HIV-1 infection and the cell surface receptors for tumor necrosis factor (TNF)-alpha, an immunoregulatory cytokine that can enhance HIV-1 replication. DESIGN: Infected promyelocytic and promonocytic cells were examined because they normally express both types of TNF receptors. METHODS: TNF receptor surface expression was determined by specific monoclonal antibody recognition and flow cytometry, and signal transduction was detected by gel shift analysis. HIV-1 activation and expression was quantitated by reverse transcriptase assay. RESULTS: In the OM-10.1 promyelocytic model of chronic infection, TNF-alpha-induced HIV-1 expression also resulted in a substantial increase in 75 kd TNF receptor (TR75) expression although 55 kD TNF receptor (TR55) levels were not dramatically altered. A series of uninfected parental HL-60 subclones all reduced TR75 surface expression in response to TNF-alpha treatment. Enhanced TR75 expression on OM-10.1 cells followed the same TNF-alpha-dose dependency as that observed for HIV-1 production. An increase in TR75 expression was also evident during the peak of an acute HIV-1 infection of HL-60 promyelocytes. Although TR55 expression was unaltered during TNF-alpha-induced HIV activation, this receptor was still involved in the viral activation process. Antibody cross-linking of TR55, in the absence of exogenous TNF-alpha, induced maximal HIV-1 expression, an up-modulation of surface TR75, and nuclear NF-kappa B activity in OM-10.1 cultures. Surprisingly, this was the case even when an antagonistic anti-TR55 antibody was used. Anti-TR55 antibody cross-linking in chronically infected U1 promonocytic cultures could only partially substitute for TNF-alpha-induced HIV-1 expression. CONCLUSIONS: Our results demonstrated that HIV-1 infection can selectively influence the surface expression of TNF receptors, potentially influencing its own expression and altering normal immunoregulatory signal transduction.

Cells, Cultured↗
PubMed1993

Differential activation of human immunodeficiency virus type 1 and 2 transcription by specific T-cell activation signals.

The human immunodeficiency virus type 1 (HIV-1) and HIV-2 enhancers are induced differentially by physiologic T-cell activation signals. In contrast to that of HIV-1, HIV-2 transcription was quite responsive to stimulation of T cells by antigen presentation but weakly induced by tumor necrosis factor alpha. Like tumor necrosis factor alpha, expression of cloned NF-kappa B subunits strongly activated the HIV-1, but not the HIV-2, enhancer. The differences in response to these physiologic T-cell activation pathways may contribute to the differences in persistence of HIV-1 and HIV-2 infection.

Base Sequence↗
PubMed1993

Differential regulation of vascular cell adhesion molecule 1 gene expression by specific NF-kappa B subunits in endothelial and epithelial cells.

Vascular cell adhesion molecule 1 (VCAM-1) is expressed in both endothelial and epithelial cell types, where it contributes to lymphocyte migration to sites of inflammation. Its expression is regulated by cytokines, in part through two kappa B-like regulatory elements. Because NF-kappa B can be composed of multiple alternative subunits with differential effects on gene expression, the role of different specific NF-kappa B family members subunits in VCAM-1 regulation is unknown. In this report, we define the contribution of different NF-kappa B family members to VCAM-1 gene regulation. We show that both kappa B sites in the VCAM-1 enhancer are required to optimally stimulate gene expression, but the enhancer is differentially regulated by specific combinations of NF-kappa B subunits. At low concentrations, RelA(p65) acted in concert with the approximately 50-kDa product of p105 NF-kappa B, NF-kappa B1(p50), to stimulate transcription, and at high concentrations, RelA(p65) alone stimulated the VCAM-1 promoter. In contrast, NF-kappa B2 inhibited functional activation of the VCAM reporter by p65. Consistent with this finding, an additional binding complex was detected by using recombinant NF-kappa B2(p49)/RelA(p65) with radiolabeled VCAM kappa B site probes. Interestingly, the human immunodeficiency virus enhancer responded differently to stimulation by NF-kappa B subunits, with optimal response to p49(100)/p65. Analysis of NF-kappa B mRNA in human umbilical vein endothelial cells revealed that nfkb1, nfkb2, and relA NF-kappa B but not c-rel were induced by tumor necrosis factor alpha and lipopolysaccharide, which also induce VCAM-1. These data suggest that specific subunits of NF-kappa B regulate VCAM-1 and differentially activate other genes in these cells.

Animals↗
PubMed1993

Inhibition of phorbol ester-induced cellular adhesion by competitive binding of NF-kappa B in vivo.

Adhesive interactions between cells are essential for the organization and function of differentiated tissues and organs and are mediated by inducible cell surface glycoproteins. In normal tissues, cell adhesion molecules contribute to immune regulation, inflammation, and embryogenesis. Additionally, they play an important role in a variety of pathogenic processes. Cell adhesion molecule expression can be induced by stimuli known to activate NF-kappa B, a ubiquitous transcription factor found in a variety of cell types. To investigate the role of NF-kappa B in cell adhesion molecule expression, we treated HL-60 cells with a double-stranded oligonucleotide which specifically inhibits NF-kappa B-mediated transcription. This treatment resulted in the inhibition of phorbol 12-myristate 13-acetate (PMA)-induced cellular adhesion, morphological changes, and the expression of leukocyte integrin CD11b. In a similar fashion, expression of intercellular adhesion molecule 1 on human endothelial cells induced by PMA was specifically inhibited by the NF-kappa B antagonist. We suggest that NF-kappa B activation is a necessary event for the PMA-induced differentiation of HL-60 cells and the expression of certain activation is a necessary event for the PMA-induced differentiation of HL-60 cells and the expression of certain adhesion molecules. Furthermore, the inhibition of transcription factor functions by this generally applicable mechanism can be used to define their role in cellular differentiation and function.

Base Sequence↗