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Biomedical subjects

A Berns

Publications and source records attributed to A Berns.

At least 127 records · Page 7Linked to original sources
PubMed1988

Transcription of T cell receptor beta-chain genes is controlled by a downstream regulatory element.

To characterize cis-acting elements controlling the expression of T cell receptor beta-chains we generated a number of transgenic mouse lines harboring a rearranged T cell receptor beta-chain with different extensions of 5' and 3' flanking sequences. Transcriptional analysis of transgenic mice carrying these clones showed that sequences located downstream of the polyadenylation signal of the C beta 2 region are indispensable for expression in transgenic mice. The sequences conferring enhancer activity in this fragment were further defined by transient CAT assays. Strong enhancer activity was found to reside in a 550 bp fragment located 5 kb downstream from C beta 2. The nucleotide sequence of this fragment revealed a number of oligonucleotide motifs characteristic for enhancer elements.

Animals↗
PubMed1988

Tissue-specific expression of a vimentin--desmin hybrid gene in transgenic mice.

We have introduced a hybrid gene, pVVim2, composed of the 5' region of the hamster vimentin gene encoding the head and rod domain of vimentin and the 3' region of the hamster desmin gene encoding the tail domain of desmin, into the germ line of mice by pronuclear injection. RNA and protein analysis of mice transgenic for this construct showed that the pVVim2 gene was expressed at high levels in a developmental and tissue-specific manner. This indicates that the vimentin-derived segment of the fusion gene contains all the regulatory elements required for vimentin-specific expression. Immunohistochemical staining of fibroblast cultures derived from the transgenic mice with antibodies specific for vimentin and desmin demonstrated that the pVVim2 protein is assembled into filaments that co-localize with the endogenous vimentin filaments. The expression of pVVim2 protein in mesenchymal cells does not interfere with the function of vimentin in these cells.

Animals↗
PubMed1988

Provirus tagging as an instrument to identify oncogenes and to establish synergism between oncogenes.

Insertional mutagenesis is one of the mechanisms by which retroviruses can transform cells. Once a provirus was found in the vicinity of c-myc, with the concomitant activation of this gene, other proto-oncogenes were shown to be activated by proviral insertion in retrovirally-induced tumors. Subsequently, cloning of common proviral insertion sites led to the discovery of a series of new (putative) oncogenes. Some of these genes have been shown to fulfill key roles in growth and development. In this review I shall describe how proviruses can be used to identify proto-oncogenes, and list the loci, identified by this method. Furthermore, I shall illuminate the potential of provirus tagging by showing that it not only can mark new oncogenes, but can also be instrumental in defining sets of (onco)genes that guide a normal cell in a step-by-step fashion to its fully transformed, metatasizing, counterpart.

Cell Transformation, Viral↗
PubMed1988

Regeneration of herpesviruses from molecularly cloned subgenomic fragments.

The ability to manipulate the genomes of herpesviruses is of eminent importance for obtaining insight into gene function and regulation of gene expression of these complex viruses. Here we report the use of in vivo overlap recombination to generate pseudorabies virus mutants. Cotransfection of up to five overlapping cloned subgenomic fragments, which together constitute the entire genomic information of pseudorabies virus, results in the efficient reconstitution of virus. This allows the efficient introduction of multiple well-defined mutations in herpesvirus genomes in a single step, without any selection or screening for a particular phenotype.

Chromosome Mapping↗
PubMed1987

Crosses of two independently derived transgenic mice demonstrate functional complementation of the genes encoding heavy (HLA-B27) and light (beta 2-microglobulin) chains of HLA class I antigens.

In man a number of diseases are associated with certain alleles of MHC antigens. The most pronounced example is ankylosing spondylitis, which is strongly associated with HLA-B27. As a first step towards a model system to study the basis of this association, transgenic mice were generated that showed cell surface expression of the HLA-B27 antigen biochemically indistinguishable from HLA-B27 antigen expressed on human cells. This result was obtained by crossing two independently derived strains of mice, one of which is transgenic for the HLA-B27 heavy chain gene, and the other carrying and expressing the human beta 2m gene. Examination of HLA-B27 and human beta 2m mRNA in various tissues shows the two genes to be expressed in a coordinate fashion. The mRNA levels follow those of endogenous H-2 Class I genes.

Animals↗
PubMed1987

Gene transfer into mammalian embryos.

Transgenic mice provide a unique system fusing classical genetics with molecular biology. They enable the dissection of molecular mechanisms underlying the control of growth and differentiation, issues we only dreamed of 20 years ago. The transgenic technology can be expected to be applied also in areas like eugenetics of animal production systems as well as genetic farming. The technology does not give an acceptable alternative for the direct treatment of human disease. However it provides unique possibilities to study genetic defects in a genetically well-defined mammalian model system. The years to come will teach us which of these expectations will come true.

Animals↗
PubMed1987

Construction and characterization of deletion mutants of pseudorabies virus: a new generation of 'live' vaccines.

Various deletions were introduced into a cloned subgenomic fragment (BamHI-7), located in the unique short (US) region of the DNA from the virulent Northern Ireland Aujeszky-3 (NIA-3) strain of pseudorabies virus (PRV). In the cloned HindIII-B fragment, the MluI-BglII fragment was replaced by different MluI-BglII fragments of the deleted BamHI-7 clones. Transfection of the deleted HindIII-B fragments together with the HindIII-A fragment of either the NIA-3 or the non-virulent NIA-4 strain yielded replication-competent deletion mutants. The region in US in which sequences were deleted specified several mRNAs. Some of the mRNAs present in cells infected with NIA-3 were absent from cells infected with the deletion mutants, whereas other differently sized mRNAs were generated. The mutants were examined with respect to their biological properties in cell culture, mice and pigs. The results showed that the type of cytopathic effect induced in cell culture seemed to be determined by the UL region, using the mean time to death in mice as a parameter, markers for virulence were present in the US and UL regions and the introduction of deletions in US strongly reduced the virulence of PRV for pigs. Despite the impaired capacity of the deletion mutants to induce high titres of neutralizing antibodies in the serum, inoculation with mutants derived from NIA-3 prevented clinical disease in pigs upon challenge with the virulent parent strain. These deletion mutants provide a good basis for the production of bioengineered live PRV vaccines.

Animals↗
PubMed1987

Comparison of the human and mouse PIM-1 cDNAs: nucleotide sequence and immunological identification of the in vitro synthesized PIM-1 protein.

Pim-1 is a putative oncogene which was discovered as a target for transcriptionally activating proviral insertions in T-cell lymphomas in mice. Its genomic and cDNA sequence have been published (Selten et al., 1986, Cell 46, 603-611). We have isolated and sequenced pim-1 cDNA clones from the human leukemia cell line K562 (h-pim-1). Comparison of human and mouse cDNA sequences reveals that both contain: (i) a GC rich leader sequence, (ii) an open reading frame encoding a 313 amino acid protein (94% conserved) showing obvious homology to protein kinases and (iii) a 1.3 kb 3' untranslated region with two polyadenylation signals and five copies of the mRNA destabilizing motif ATTTA. "In vitro" translation experiments show that both mouse and human cDNA derived RNA can translate into a protein of the expected size. Their identity was confirmed by immuno-precipitation with antisera raised against synthetic pim-1 oligopeptides.

Amino Acid Sequence↗
PubMed1986

The primary structure of the putative oncogene pim-1 shows extensive homology with protein kinases.

We have shown previously that the putative oncogene pim-1 is frequently activated by provirus insertion in murine leukemia virus-induced T cell lymphomas. Here we describe the structure of the pim-1 gene as determined by sequencing genomic and cDNA clones. The gene has an open reading frame, encoding a protein of 313 amino acids, extending over six exons and preceded and followed by stop codons in all reading frames. Proviruses always integrate outside the protein-encoding domain, showing a high preference for a small region in the 3'-terminal exon; integration in the 3' exon results in relatively high levels of pim-1 mRNA. Computer search reveals homology between pim-1 and protein kinases: all the domains characteristic of protein kinases are conserved in the pim-1 amino acid sequence. The highest homologies were observed with the protein-serine kinases.

Amino Acid Sequence↗
PubMed1986

Genetic mapping of Pim-1 putative oncogene to mouse chromosome 17.

Pim-1 is a putative oncogene activated in T-cell lymphomas induced by Moloney and AKR mink cell focus forming (MCF) viruses. We have determined the chromosomal localization of the Pim-1 gene in mice by Southern blot analysis of DNAs obtained from a panel of mouse-Chinese hamster somatic cell hybrids. The Pim-1 gene was localized on chromosome 17, a chromosome frequently aberrant in T-cell lymphomas. Two chromosomal regions, containing sequences homologous to regions within the Pim-1 locus, were localized on chromosome 6 and 16.

Animals↗
PubMed1986

Immunologic induction of malignant lymphoma: graft-vs-host reaction-induced B cell lymphomas contain integrations of predominantly ecotropic murine leukemia proviruses.

The induction of a graft-vs-host reaction in (BALB/c X A)F1 mice by i.v. injection with BALB/c lymphoid cells leads to a lymphoid hyperplasia that may progress to malignant lymphoma. In the present paper, the following aspects of graft-vs-host-reaction lymphomagenesis were studied: 1) the cellular requirements for the induction of lymphomas, 2) their cellular origin, and 3) the role of murine leukemia viruses. The development of graft-vs-host-reaction lymphomas was found to be mediated by donor T cells and to require the presence of histoincompatibility between donor and host. Histologically, the vast majority of these lymphomas were either of follicular center cell or of immunoblastic type, whereas immunoperoxidase studies showed that they were virtually all B cell derived. Most of the lymphomas were of host origin. In the DNA of approximately 80% of the lymphomas, integrated murine leukemia virus proviruses were detected. In the B cell lymphoma DNA, integrated ecotropic proviruses prevailed, but recombinant murine leukemia virus and/or deleted murine leukemia virus genomes were also detected in some tumor DNA.

Animals↗
PubMed1985

Proviral activation of the putative oncogene Pim-1 in MuLV induced T-cell lymphomas.

Proviral integration near the Pim-1 gene is frequently observed in murine leukemia virus induced T-cell lymphomas in mice. Integration in the Pim-1 domain is associated with the presence of enhanced levels of a Pim-1 mRNA, which is normally expressed as a predominant 2.8 kb species at low levels in lymphoid tissues. The majority of integrations occurred in the 3' region of the Pim-1 transcription unit. This resulted in transcripts ranging in size from 2.0 to 2.6 kb, which were terminated in the 5' proviral LTR. Dependent on the site of integration up to 1300 bases of Pim-1 specific sequences were missing from the modified Pim-1 mRNA in these lymphomas.

Animals↗
PubMed1985

Presence of markers for virulence in the unique short region or repeat region or both of pseudorabies hybrid viruses.

The unique short region and part of the repeat region of virulent pseudorabies virus strain NIA-3 was replaced by the corresponding region of the avirulent NIA-4 strain by transfection with subgenomic DNA fragments. The resulting hybrid virus showed a reduced virulence in both mice and pigs. Therefore, important markers for virulence are located in the unique short or repeat region or both of pseudorabies virus. We provide evidence that the terminally located repeat is not required for the generation of progeny with intact pseudorabies virus genomes. Apparently, the terminal repeat is regenerated from the internal repeat.

Animals↗
PubMed1984

Involvement of c-myc in MuLV-induced T cell lymphomas in mice: frequency and mechanisms of activation.

In approximately 45% of the murine leukemia virus (MuLV) induced early developing T cell lymphomas in mice, integration of proviruses occurs near c-myc. From the 33 lymphomas with proviral integrations in the c-myc domain, 29 insertions were localized upstream of the first exon in a region spanning less than 2 kbp, and four integrations occurred within the first exon. In 90% of the lymphomas the transcriptional orientation of the proviruses was opposite to the transcriptional direction of c-myc. In 20% of the early T cell lymphomas, proviral integrations were detected both near c-myc and the pim-1 gene. They comprise both lymphomas in which integration near c-myc and pim-1 occurred in separate tumor cell populations, as well as tumors in which proviral integration near c-myc and pim-1 occurred in the same cell clone. Proviral integration in the c-myc domain is associated with increased myc mRNA levels (up to 30-fold). The size and nature of the c-myc mRNA precursors and processed transcripts depend on the position and orientation of the integrated proviruses.

Animals↗
PubMed1984

Generation of AKR mink cell focus-forming virus: nucleotide sequence of the 3' end of a somatically acquired AKR-MCF.

The 3' end of an AKR-MCF provirus (MCFr35) was cloned and found to be biologically active. Comparison of the nucleotide sequence of MCFr35 with the sequence of other MuLVs revealed that the MCFr35 was most likely derived from the same xenotropic and ecotropic parents, which were involved in the generation of AKR-MCF247. Ecotropic sequences are present around the XbaI site at position 7.9 on the genomic map, and in the long terminal repeat. Most of the T1 oligonucleotide sequences, characteristic for the leukemogenic "class I" MCFs, are also present in MCFr35, with the exception of T1 oligonucleotides 108 and 18. The MCFr35 LTR contains a duplicated enhancer sequence from a xenotropic-like provirus, which is present only once per haploid genome equivalent. The 3' end of MCFr35 consist predominantly of nonecotropic sequences, thereby delimiting the positions of recombination in various MCF viruses.

Amino Acid Sequence↗
PubMed1984

How to make an affiliate model work--a case history.

The North Shore Community Mental Health Center has an unusual mental health delivery system. "Out-stationed" staff work in affiliated agencies, yet are employees of the NSCMHC. This service configuration is the result of an arduous planning process which weighed the advantages of several organizational models. On one extreme was a "Centralized" model, wherein one organization was solely responsible for delivering mental health services. On the other extreme was an "Umbrella" model, wherein the organization acted as a fiscal conduit to several service providers. Somewhere in the middle a compromise was found with a "Lead Agency" model. Here, an organization provides the administrative structure, provides some services, and subcontracts the remaining services. The North Shore Community Mental Health Center adapted this system one step further. Rather than subcontracting services, it outstationed CMHC staff to affiliate agencies. United Cerebral Palsy Association of the North Shore is one of the CMHC's affiliates. The service need for family and play therapists resulted in two CMHC therapists being outstationed at UCP. The affiliation agreement between the two organizations specify the responsibilities and roles each have. The hiring process between the two organizations is an example of the duality of the system. Both agencies had interviewing roles, yet the final hiring decision was the affiliate's, since the employee would spend the majority of his/her time outstationed at the affiliate side. Outstationed staff integration to the North Shore Community Mental Health Center presented problems, however. Since these were new staff hired with federal funds, and since their visibility at the Center was minimal, they had some difficulty being identified as Center staff by existing employees.(ABSTRACT TRUNCATED AT 250 WORDS)

Community Mental Health Services↗
PubMed1984

Murine leukemia virus-induced T-cell lymphomagenesis: integration of proviruses in a distinct chromosomal region.

A number of mink cell focus-forming (MCF) proviruses was molecularly cloned from mouse lymphoma DNA. From each clone, flanking probes were prepared to detect common integration regions in other MuLV-induced lymphomas. One clone frequently revealed variations in the molecular structure of the corresponding region (Pim-1) in other lymphomas. The results show the following. Changes in the Pim region are seen in 24 out of 93 lymphomas tested. Over 50% of the early T-cell lymphomas show integration in the Pim-1 region. The alterations are seen in different mouse strains and with various MuLVs. The observed variations are caused by the integration of predominantly MCF genomes. All integrations occur in a region spanning less than 20 kb and are associated with the transcriptional activation of a distinct region within the Pim-1 domain. The activated region does not show any homology with 13 known and three putative oncogenes.

Animals↗