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J Hiscott

Publications and source records attributed to J Hiscott.

118 records · Page 7Linked to original sources
PubMed1988

Modulation of nuclear proto-oncogene expression and cellular growth in myeloid leukemic cells by human interferon alpha.

To address the mechanisms that regulate expression of specific growth-related nuclear proto-oncogenes, the transcript levels of the c-fos, c-myc, (2'5')-oligoadenylate synthetase, IFN-alpha 1, and IFN-beta 1 genes have been measured in the human leukemic cell lines KG-1, U937, and HL-60 following growth stimulation by serum, induction of differentiation by tumor-promoting agents, and/or treatment of cells with exogenously supplied alpha interferon (rIFN-alpha 2). Production of fos and myc RNA was measured by S1 mapping, using fos DNA probes which identified either primary unspliced transcripts or steady-state-spliced mRNA levels, and using a myc probe which spanned the two major c-myc start sites, P1 and P2. Pretreatment of a quiescent KG-1 cell population with IFN for 18 hours before serum addition decreased the stimulation of both fos and myc RNA production. In HL-60 and U937 cells, IFN pretreatment had no inhibitory effect on serum-induced fos or myc transcription; however, in U937, rIFN-alpha 2 treatment alone stimulated fos mRNA 11-fold. Expression of 2'5'oligoadenylate synthetase was induced in IFN-treated cultures but not in cells stimulated with serum alone. No serum-induced IFN-alpha 1 or IFN-beta 1 gene expression was observed in KG-1 or U937 cells. These results demonstrate that exogenous rIFN-alpha 2 treatment of quiescent KG-1 cells can antagonize the effect of growth factors by altering expression of nuclear proto-oncogenes, but in general growth inhibition is not obligatorily coupled to inhibition of proto-oncogene transcription.

Cell Division↗
PubMed1988

trans activation of type 1 interferon promoters by simian virus 40 T antigen.

A human transient expression system was used to measure the influence of simian virus 40 T antigen and adenovirus E1a proteins on the activation of alpha interferon subtype 1 (IFN-alpha 1) and IFN-beta promoters linked to the reporter chloramphenicol acetyltransferase gene. Large T-antigen production, amplified by expression plasmid replication in transfected 293 cells, was able to trans activate the IFN-beta promoter 5- to 10-fold, increasing both the constitutive and Sendai virus-induced levels of expression. Surprisingly, the previously quiescent transfected IFN-alpha 1 promoter in T-antigen-expressing cells displayed a level of inducibility similar to IFN-beta. The endogenous IFN-alpha 1 gene was also inducible to a limited extent in cells expressing T antigen. A truncated IFN-beta promoter deleted to position -37 relative to the CAP site was neither inducible nor trans activated by T antigen, suggesting that sequences required for efficient induction were also needed for trans activation. Since 293 cells express adenoviral E1a proteins, experiments were also performed in HeLa cells to assess the relative contribution of T antigen and E1a proteins to IFN trans activation. In HeLa cells, T-antigen coexpression increased the constitutive level of IFN-beta and IFN-alpha 1 promoter activity without augmenting relative inducibility. Coexpression of T antigen and E1a proteins did not have a cooperative effect on type 1 IFN expression.

Adenovirus Early Proteins↗
PubMed1987

Identification of a nuclear DNA binding protein associated with the interferon-beta upstream regulatory region.

Nuclear protein extracts were prepared from uninduced myeloid leukemic KG-1 cells and analyzed for interferon-specific DNA binding by a gel electrophoresis DNA binding assay. A protein was detected that bound specifically to a 163-base pair upstream region of the IFN-beta promoter. A series of competition studies were performed to assess whether this was a general DNA binding protein; binding of this factor was competed from radiolabeled beta 163 fragment only by an excess of cold unlabeled beta 163 or a 67-base pair fragment (beta 67) derived from beta 163. Other promoter and enhancer transcriptional domains including 1) c-fos serum responsive element, 2) c-fos promoter, 3) SV40 enhancer, 4) IFN-alpha 1 promoter, and 5) plasmid pAT153 did not compete effectively for binding of the protein. These results indicate that this protein is not a general enhancer or promoter binding factor and may be unique to IFN-beta. Analysis of beta 67 DNA sequences revealed no homology to known recognition sequences for Sp1 or CTF transcription factors.

Cell Line↗
PubMed1987

Transient expression of the beta interferon promoter in human cells.

A human transient expression assay was used to examine the inducible transcriptional activation of beta interferon (IFN-beta) and IFN-alpha 1 promoters in a homologous cellular environment. Use of 293 cells, an adenovirus DNA-transformed human embryonic kidney cell line, permitted Sendai virus-inducible expression of IFN-beta-CAT hybrid gene. Introduction of the simian virus 40 (SV40) enhancer 5' or 3' to the IFN-CAT gene increased basal (uninduced) levels of chloramphenicol acetyltransferase (CAT) activity; in one construct the SV40 enhancer--IFN-beta regulatory region combination increased the induced CAT activity 50- to 100-fold, suggesting that this may be a generally useful inducible enhancer-promoter combination. No expression from the IFN-alpha-CAT hybrid gene was detected in 293 cells, indicating that human epithelioid cells lack a factor required for expression of the IFN-alpha promoter. However, when the IFN-alpha regulatory region was combined with the SV40 enhancer, a low level of inducible CAT activity was detected in the human transient system.

Cell Line↗
PubMed1984

The expression of human interferon alpha genes.

We have determined the levels of mRNAs for IFN-beta, IFN-gamma and various alpha-IFNs (IFN-alpha 1, -alpha 2, -alpha 4, -alpha 5, -alpha 6, -alpha 7, -alpha 8 and -alpha 14) in normal and leukaemic human blood leucocytes and several cell lines induced in different fashions. The ratio of alpha to beta IFN transcripts varied greatly, depending on the cell type. The levels of the individual IFN-alpha RNAs were very different: IFN-alpha 1, -alpha 2 and -alpha 4 RNAs constituted the major fraction of the IFN-alpha transcripts measured, while IFN-alpha 6, -alpha 7, -alpha 8 and -alpha 14 were minor components in normal, induced leucocytes. Moreover, there was a striking difference in the proportion of individual IFN-alpha mRNA species in different cell types, in particular between normal and leukaemic cells; for example all cases of myeloblastic leukaemia examined showed a high expression of IFN-alpha 14. Use of different induction protocols did not significantly affect the proportion of IFN mRNAs. Analysis of the human IFN-alpha 1 gene by reversed genetics led to the identification of a segment of 5' flanking sequence between positions 117 and 68 upstream of the cap site which is required for inducibility by virus.

Cell Line↗
PubMed1984

Differential expression of human interferon genes.

We developed a method for quantitating closely related mRNAs by S1 mapping and used it to determine the levels of mRNAs for IFN-beta, IFN-gamma and various alpha IFNs (IFN-alpha 1, -alpha 2, -alpha 4, -alpha 5, -alpha 6, -alpha 7, -alpha 8 and -alpha 14) in human peripheral blood leukocytes, lymphoblastoid (Namalwa), HeLa and human fibroblastic cells, induced in different fashions. The ratio of alpha to beta IFN transcripts varied greatly, depending on the cell type. The levels of the individual IFN-alpha RNAs were very different: IFN-alpha 1, -alpha 2 and -alpha 4 RNAs constituted the major fraction of the IFN-alpha transcripts measured. Moreover, there was a striking difference in the proportion of individual IFN-alpha mRNA species in different cell types. Use of different induction protocols did not significantly affect the proportion of IFN mRNAs. IFN production was not proportional to mRNA level in all cases, as lymphoblastoid cells induced by incubation at high density and virus-induced HeLa cells contained high levels of IFN-beta but produced little antiviral activity.

Burkitt Lymphoma↗
PubMed1980

Amplification and rearrangement of integrated SV40 DNA sequences accompany the selection of anchorage-independent transformed mouse cells.

Clones of SV40 tsA mutant-transformed mouse embryo cells with a temperature-independent transformed growth phenotype were derived from a parental line with a temperature-dependent growth phenotype, using the selective pressure of anchorage independent growth in agar at 40 degrees C. The parental J78 clone contained a complex tandem structure of integrated SV40 DNA within two cellular DNA fragments of 10 and 14 kb, generated by Bgl II digestion. The new clonal derivatives, in addition to an altered growth phenotype, displayed additional high molecular weight sites of SV40 DNA integration. A marked structural similarity among integration sites suggested that the new sites may have arisen by duplication and translocation of an original integration structure, or via an unequal crossover event. The rearrangement of viral DNA sequences appears to be specifically associated with the emergence of temperature-independent clones, since the isolation of new clones under nonselective conditions, that is, growth in semi-solid medium at 33 degrees C, was not accompanied by modification in cellular sequences containing SV40 DNA.

Animals↗
PubMedDate not supplied

Role of the interferon regulatory factors (IRFs) in virus-mediated signaling and regulation of cell growth.

As a response to viral infection, cells express the early inflammatory genes that encode small proteins generally called cytokines or chemokines. These protein can activate immune responses to viral infection as well as to modulate directly the outcome of viral infection. The group of proteins with the direct antiviral effects have been called interferons. The stimulation of interferon synthesis in infected cells is regulated on a transcriptional level and two families of cellular transcriptional factors seem to play a critical role in the transcriptional activation of interferon genes. The first one are the proteins of NF-kappaB family and the second is the family of the interferon responsive factors. While both of the types of the transcriptional factors are important for the induction of interferon beta gene, the NF-kappaB factor do not seems to participate in the induction of interferon alpha genes. The present review is focused on the recently identified new members of cellular IRF family and their role in virus mediated response, responses and cell growth. In addition the HHV-8 encoded vIRFs are described.

Cell Division↗
PubMedDate not supplied

NF-kappaB activation and HIV-1 induced apoptosis.

HIV infection leads to the progressive loss of CD4+ T cells and the near complete destruction of the immune system in the majority of infected individuals. High levels of viral gene expression and replication result in part from the activation of NF-kappaB transcription factors, which in addition to orchestrating the host inflammatory response also activate the HIV-1 long terminal repeat. NF-kappaB induces the expression of numerous cytokine, chemokine, growth factor and immunoregulatory genes, many of which promote HIV-1 replication. Thus, NF-kappaB activation represents a double edged sword in HIV-1 infected cells, since stimuli that induce an NF-kappaB mediated immune response will also lead to enhanced HIV-1 transcription. NF-kappaB has also been implicated in apoptotic signaling, protecting cells from programmed cell death under most circumstances and accelerating apoptosis in others. Therefore, activation of NF-kappaB can impact upon HIV-1 replication and pathogenesis at many levels, making the relationship between HIV-1 expression and NF-kappaB activation multi-faceted. This review will attempt to analyse the many faces and functions of NF-kappaB in the HIV-1 lifecycle.

Acquired Immunodeficiency Syndrome↗