The Epstein-Barr virus 3.5-kilobase latent membrane protein 1 mRNA initiates from a TATA-Less promoter within the first terminal repeat.

The complete 5' sequence of the Epstein-Barr virus 3.5-kb latent membrane protein 1 (LMP1) mRNA, expressed in nasopharyngeal carcinoma, has been determined. The transcript initiates from heterogeneous start sites within the first terminal repeat (TR) of the viral genome.

Phenobarbital modulates the type of cell death by rat hepatocytes during deprivation of serum in vitro.

An immortal line of chemically altered rat hepatocytes was used to study the effects of the liver tumor promoter, phenobarbital (PB), on hepatocyte growth and viability in vitro. When the serum concentration in medium was changed from 10% to 0.5%, cell proliferation decreased and hepatocytes died.

p53 and its 14 kDa C-terminal domain recognize primary DNA damage in the form of insertion/deletion mismatches.

Insertion/deletion (IDL) mismatches in DNA are lesions consisting of extra bases on one strand. Here, the binding of p53 and its 14 kDa C-terminal domain to DNAs containing one or three 3-cytosine IDL mismatches was examined. Electron microscopy showed that both p53 forms bound predominantly as tetramers at the lesions while single-stranded binding proteins did not bind.

Cloning and developmental expression analysis of the murine c-mer tyrosine kinase.

We have cloned the putative mouse homologue of the human c-mer receptor tyrosine kinase proto-oncogene. Comparison of the mouse and human c-mer amino acid sequences reveals an overall identity of 88%. Similar to the human, the extracellular region of the murine c-mer protein possesses two amino terminal immunoglobulin-like domains and two membrane proximal fibronectin type III domains, which places it in the Axl family of tyrosine kinases.

A proliferative p53-responsive element mediates tumor necrosis factor alpha induction of the human immunodeficiency virus type 1 long terminal repeat.

Transforming mutants of the p53 tumor suppressor gene can positively regulate transcription from several promoters that do not contain known p53 binding sites. Here, we report the identification of a novel p53 binding site in the human immunodeficiency virus long terminal repeat that specifically mediates mutant p53 transactivation. This DNA element was bound by endogenous Jurkat p53 when these cells were stimulated by tumor necrosis factor.

Physical and functional interaction of the Epstein-Barr virus BZLF1 transactivator with the retinoic acid receptors RAR alpha and RXR alpha.

Epstein-Barr virus (EBV) reactivation, indicated by induction of EBV early antigens from latently infected lymphoid cell lines by phorbol esters, is inhibited by retinoic acid (RA). Viral reactivation, which is triggered by the immediate-early BZLF-1 (Z) viral gene product, is repressed by retinoic acid receptors (RARs) RAR alpha and RXR alpha. These proteins negatively regulate Z-mediated transactivation of the promoter for an EBV early gene product, early antigen-diffuse (EaD).

Derivation of phenobarbital-responsive immortal rat hepatocytes.

Two lines of rat hepatocytes, designated 6/15 and 6/27, were obtained from carcinogen-treated livers by cultivation in medium containing the liver tumor promoter, phenobarbital (PB). Both lines appeared to be PB-responsive and to have an unlimited in vitro proliferative lifespan, i.e.

Transcription-independent turnover of I kappa B alpha during monocyte adherence: implications for a translational component regulating I kappa B alpha/MAD-3 mRNA levels.

We identified I kappa B alpha/MAD-3 as an immediate-early gene in human monocytes that is expressed in response to a variety of signals, including adhesion, lipopolysaccharide, and phorbol myristate acetate. Within 5 min of monocyte adhesion, the level of the I kappa B alpha protein is markedly diminished but is rapidly replaced in a cycloheximide-sensitive manner within 20 min. Accompanying the rapid turnover of the I kappa B alpha protein is simultaneous translocation of NF-kappa B-related transcription factors to nuclei of adhered monocytes.

The transcriptional regulatory protein, YB-1, promotes single-stranded regions in the DRA promoter.

YB-1 is a member of a newly defined family of DNA- and RNA-binding proteins, the Y box factors. These proteins have been shown to affect gene expression at both the transcriptional and translational levels. Recently, we showed that YB-1 represses interferon-gamma-induced transcription of class II human major histocompatibility (MHC) genes (1).

Structural analyses of the Epstein-Barr virus BamHI A transcripts.

Epstein-Barr virus (EBV) gene expression in nasopharyngeal carcinoma (NPC) includes abundant rightward transcription of the BamHI A fragment, consisting of mRNAs ranging in size from approximately 4.0 to 8.0 kb.

Attenuation of G2 checkpoint function precedes human cell immortalization.

We have investigated the hypothesis that attenuation of the G2 checkpoint, which delays entry into mitosis in response to damage to DNA and protects against clastogenesis, may contribute to the genetic instability of immortal human cell lines. IMR-90 normal human fibroblasts displayed stringent G2 checkpoint response to gamma-radiation-induced DNA damage. Irradiation with 1.

Electron microscopic studies of the interaction between a Bacillus subtilis alpha/beta-type small, acid-soluble spore protein with DNA: protein binding is cooperative, stiffens the DNA, and induces negative supercoiling.

DNA within spores of Bacillus subtilis is complexed with a group of alpha/beta-type small acid-soluble spore proteins (alpha/beta-type SASPs), which have almost identical primary sequences and DNA binding properties. Here electron microscopic and cyclization studies were carried out on alpha/beta-type SASP-DNA complexes. When an alpha/beta-type SASP was incubated with linear DNA, the protein bound cooperatively, forming a helical coating 6.

Characterization of HIV-1 protease mutants: random, directed, selected.

The HIV-1 protease is becoming one of the most important proteins in medicine. It is perhaps the most attractive target for development of an anti-HIV-1 therapeutic drug. Given its pre-eminent position in biomedical research, many aspects of the protease are currently coming under close scrutiny.

Productive infection of human endometrial stromal cells by human cytomegalovirus.

Cultured endometrial stromal cells were susceptible to productive human cytomegalovirus (HCMV) infection. Infection of endometrial stromal cells resulted in pronounced cytopathic effects including cell rounding and aggregation, fusions, and some lysis, although not in the synchronous fashion observed in infected fibroblasts. The aggregation events were reminiscent of normal endometrial stromal cell responses to cyclical estrogen/progesterone levels.

Cloning and mRNA expression analysis of a novel human protooncogene, c-mer.

A human B-lymphoblastoid lambda gt11 expression library was screened using anti-phosphotyrosine antibodies yielding complementary DNAs encoding active tyrosine kinases. The resulting clones were used to obtain the sequence of a novel 984 amino acid transmembrane tyrosine kinase. Analysis of the complementary DNA revealed extracellular immunoglobulin and fibronectin type III domains and the unusual kinase signature sequence KWIAIES; all are characteristic of the axl family of tyrosine kinases.

Function of NF-kappa B/Rel binding sites in the major histocompatibility complex class II invariant chain promoter is dependent on cell-specific binding of different NF-kappa B/Rel subunits.

The promoter of the human major histocompatibility complex class II-associated invariant-chain gene (Ii) contains two NF-kappa B/Rel binding sites located at -109 to -118 (Ii kappa B-1) and -163 to -172 (Ii kappa B-2) from the transcription start site. We report here that the differential function of each of these NF-kappa B/Rel sites in several distinct cell types depends on cell-specific binding of NF-kappa B/Rel transcription factors. Ii kappa B-1 is a positive regulatory element in B-cell lines and in the Ii-expressing T-cell line, H9, but acts as a negative regulatory element in myelomonocytic and glia cell lines.

YB-1 DNA-binding protein represses interferon gamma activation of class II major histocompatibility complex genes.

Interferon gamma (IFN-gamma) is the most potent inducer of class II major histocompatibility complex (MHC) genes. This induction is uniquely mediated by three DNA elements in the promoter region of class II MHC genes. One of these DNA elements, Y, contains an inverted CCAAT box.

Prognostic importance of mutations in the ras proto-oncogenes in de novo acute myeloid leukemia.

Mutations of the N- and K-ras genes are the most frequent genetic aberrations in acute myeloid leukemia (AML) and their detection in preleukemic conditions such as the myelodysplastic syndrome (MDS) suggests a role in the earliest phases of leukemogenesis. Despite these observations, little is known about the clinical importance of ras mutations in AML. We studied the clinical impact of ras mutations in 99 patients with de novo AML.

The bZIP transactivator of Epstein-Barr virus, BZLF1, functionally and physically interacts with the p65 subunit of NF-kappa B.

The Epstein-Barr virus (EBV) BZLF1 (Z) immediate-early transactivator initiates the switch between latent and productive infection in B cells. The Z protein, which has homology to the basic leucine zipper protein c-Fos, transactivates the promoters of several replicative cycle proteins. Transactivation efficiency of the EBV BMRF1 promoter by Z is cell type dependent.

Synergistic activation of tyrosine phosphorylation by o-vanadate plus calcium ionophore A23187 or aromatic 1,2-diols.

We have shown previously that treatment of WB rat liver epithelial cells with the Ca2+ ionophore A23187 provokes a rapid increase in protein-tyrosine phosphorylation that faithfully reproduces the Ca(2+)-dependent response seen with angiotensin II. In the presence of the tyrosine phosphatase inhibitor o-vanadate (2.0-200 microM), the tyrosine phosphorylation response to A23187 was increased > 10-fold in magnitude.

G1 arrest and cell-cycle-dependent clastogenesis in UV-irradiated human fibroblasts.

The demonstrations of frequent allelic deletions in lung and colon cancers have reemphasized the importance of clastogenesis in carcinogenesis. We have investigated the mechanisms of induction of chromosome aberrations in ultraviolet-irradiated diploid human fibroblasts. Cells were irradiated with UV at various times during a parasynchronous wave of cell proliferation and then harvested during the first mitosis that followed irradiation.

Human major histocompatibility complex class II-associated invariant chain gene promoter. Functional analysis and in vivo protein/DNA interactions of constitutive and IFN-gamma-induced expression.

Major histocompatibility complex (MHC) class II-associated invariant chain (Ii) gene and the MHC class II molecules are physically and functionally associated within class II-expressing cell types. These genes are generally co-expressed in various cell types and coordinately induced by cytokines such as interferon-gamma (IFN-gamma). Human Ii gene shares a regulatory mechanism with MHC class II genes via the X and Y cis-acting elements.

In vitro expression of the human cytomegalovirus DNA polymerase gene: effects of sequence alterations on enzyme activity.

Genomic DNA of the Towne strain human cytomegalovirus polymerase (pol) gene (4.4-kb RsrII-NcoI segment of the EcoRI J fragment) was cloned into plasmids containing either the T3 or the T7 promoter for in vitro transcription-translation studies. The translation efficiency of unmodified pol cRNA was poor in this system and could not be improved by capping.