PubMed Health⌕ Search

Biomedical subjects

G Scangos

Publications and source records attributed to G Scangos.

14 recordsLinked to original sources
PubMed2000

Differential effects on T cell and NK cell development by tissue-specific expression of H-2D(d) transgene.

The effect of tissue-specific expression of the MHC class I molecule H-2D(d) on T cell and NK cell specificity was studied in transgenic mice expressing the H-2D(d) gene under the control of the mouse metallothionein-I promoter. MTD mice expressed high amounts of H-2D(d) in the liver, intestine and testis, but only minute amounts in the thymus, spleen and kidney. Zinc administration resulted in a 1.5- and 8.5-fold increase in H-2D(d) expression in the liver and the intestine, respectively, but did not affect expression in the other organs tested. T cell tolerance developed towards H-2D(d) in MTD mice, even in the absence of zinc. In contrast, NK cell-mediated natural resistance against lymphoma grafts was not seen in MTD mice, despite zinc administration. NK cells in MTD mice also failed to develop self tolerance to H-2D(d). The lack of functional effects did not result from inability of NK cells in MTD mice to interact with H-2D(d), as down-regulation of Ly49A receptor expression was observed on liver NK cells in MTD mice. Our data reveal a difference between T cells and NK cells in their requirements for MHC class I molecules in specificity development.

Animals↗
PubMed1989

Prevention of allogeneic bone marrow graft rejection by H-2 transgene in donor mice.

Rejection of bone marrow grafts in irradiated mice is mediated by natural killer (NK) cells and is controlled by genes linked to the major histocompatibility complex (MHC). It has, however, not been possible to identify the genes or their products. An MHC class I (Dd) transgene introduced in C57BL donors prevented the rejection of their bone marrow by NK cells in irradiated allogeneic and F1 hybrid mice expressing the Dd gene. Conversely, H-2Dd transgenic C57BL recipients acquired the ability to reject bone marrow from C57BL donors but not from H-2Dd transgenic C57BL donors. These results provide formal evidence that NK cells are part of a system capable of rejecting cells because they lack normal genes of the host type, in contrast to T cells, which recognize cells that contain abnormal or novel sequences of non-host type.

Animals↗
PubMed1988

Natural resistance against lymphoma grafts conveyed by H-2Dd transgene to C57BL mice.

The H-2Dd transgenic strain D8 on C57BL background was more resistant to subcutaneous challenge of RBL-5 lymphoma cells than B6 controls. The direct role of the H-2Dd antigen was investigated by the use of (D8 x B6)F1 crosses and (D8 B6) x B6 backcrosses. The latter showed cosegregation with regard to Dd antigen expression and lymphoma resistance, both of which were inherited in a pattern consistent with control by a single dominant gene. The rejection potential in (D8 x B6)F1 mice appeared as strong as that seen in crosses between B6 and MHC congenic mice (on B10 background) carrying H-2Dd. The lymphoma resistance could be abrogated by treatment with anti-asialo GM1 antiserum or anti-NK 1.1 mAb, indicating a role for NK cells.

Animals↗
PubMed1987

A transgenic class I antigen is recognized as self and functions as a restriction element.

The function of a transgenic Dd class I molecule in the induction of immunologic tolerance to major histocompatibility complex antigens and in directing major histocompatibility complex restriction in C57BL/6 mice were investigated. All of the transgenic Dd mouse strains were found to be tolerant for the Dd antigen. Spleen cells from transgenic mice were immunocompetent but consistently failed to generate an anti-Dd cytotoxic T lymphocyte response in vitro, and skin grafts between transgenic Dd mice were not rejected. These data suggests that the Dd antigen was recognized as a self molecule. In addition, the transgenic Dd mice generated antigen-specific Dd-restricted cytotoxic T lymphocyte, indicating that the Dd antigen also functioned as a restriction element for antigen recognition. These observations demonstrate the usefulness of the transgenic mouse system for studying class I antigen expression and function.

Animals↗
PubMed1987

Functional expression of a heterologous major histocompatibility complex class I gene in transgenic mice.

The regulated expression of major histocompatibility complex class I antigens is essential for assuring proper cellular immune responses. To study H-2 class I gene regulation, we have transferred a foreign class I gene to inbred mice and have previously shown that the heterologous class I gene was expressed in a tissue-dependent manner. In this report, we demonstrate that these mice expressed the transgenic class I molecule on the cell surface without any alteration in the level of endogenous H-2 class I antigens. Skin grafts from transgenic mice were rapidly rejected by mice of the background strain, indicating that the transgenic antigen was expressed in an immunologically functional form. As with endogenous H-2 class I genes, the class I transgene was inducible by interferon treatment and suppressible by human adenovirus 12 transformation. Linkage analysis indicated that the transgene was not closely linked to endogenous class I loci, suggesting that trans-regulation of class I genes can occur for class I genes located outside the major histocompatibility complex.

Animals↗
PubMed1986

Regulated expression of a murine class I gene in transgenic mice.

The major histocompatibility complex class I genes play an essential role in the immune presentation of aberrant cells. To gain further insight into the regulation of the expression of these class I genes and to better define the functions of their protein products, we made use of the technique of gene transfer into the germ line of inbred mice. With the use of locus-specific DNA probes, we observed that a transgenic class I gene was expressed in a tissue-dependent fashion analogous to that of an endogenous class I gene. In addition, the level of expression of the transgenic gene was substantially higher that that of the endogenous gene. The availability of transgenic mice properly expressing a foreign murine class I gene provides a unique system to further define the role of the class I antigens in the maturation of the immune response and in determining the malignant and metastatic phenotypes of tumor cells.

Animals↗
PubMed1983

Recombination during gene transfer into mouse cells can restore the function of deleted genes.

Two plasmids containing nonoverlapping deletions of the herpes simplex virus thymidine kinase gene were introduced into thymidine kinase-deficient mouse L cells by DNA-mediated gene transfer. Thymidine kinase-producing transformants were generated by a mixture of the two plasmids at a frequency significantly greater than that generated by either plasmid alone. Southern blot analyses demonstrated that functional thymidine kinase genes were generated by homologous recombination between the two deletion mutants.

Animals↗
PubMed1982

Expression of transferred thymidine kinase genes is controlled by methylation.

Plasmid pTKx-1, containing the herpes simplex virus gene for thymidine kinase (TK) inserted into the BamHI site of plasmid pBR322, was introduced into Ltk- cells by calcium phosphate precipitation in the absence of carrier DNA. Line 101 is a TK+ derivative of Ltk- that contains multiple copies of pTKx-1 in a multimeric structure. A derivative of 101 that retained but no longer expressed the herpes simplex TK genes (termed 101BU1) and derivatives of line 101BU1 that reexpressed the genes (termed 101H1, 101HC, and 101HG) were selected. The TK genes in 101BU1 were hypermethylated relative to those in the TK+ parent and derivatives. Growth of 101BU1 in the presence of the methylation inhibitor 5-azacytidine resulted in an average 13-fold increase in the number of TK+ reexpressors, DNA from 101BU1 was inactive in secondary gene transfer, whereas DNA from 101 and from TK+ reexpressors was active. These data support a causative relationship between DNA methylation and decreased gene expression. All TK+ reexpressors examined had DNA rearrangements involving TK DNA.

Animals↗
PubMedDate not supplied

Mechanisms and applications of DNA-mediated gene transfer in mammalian cells - a review.

The ability of mammalian cells to take up exogenously added DNA and to express genes included on that DNA has been well documented. DNA-mediated gene transfer (DMGT) potentially is a useful technique for the elucidation of many of the factors that control gene expression, and for the purification and isolation of mammalian genes. Before many of the benefits can be realized, however, a more detailed understanding of the organization, intracellular location, and expression of transferred genes will be needed. Recent studies have begun to characterize the DMGT process. Selected genes become linked to other exogenously added DNA during or subsequent to transfer and persist in the nuclei of recipient cells as part of large molecules called transgenomes. Transgenomes initially are maintained unstably and are lost from the population with first order kinetics. After a variable number of generations in culture, subpopulations arise that maintain the transferred genes stably. In these "stable" cells the transgenome is associated with a recipient cell chromosome, although the particular chromosome differs in independent "stable" lines. Mixture of an excess of specific nonselectable genes with the selected gene prior to transfer results in the inclusion of the nonselected genes in the transgenomes present in most cells that survive selection. This finding demonstrates the feasibility of introducing virtually any purified gene into mammalian cells. Recently microinjection of DNA directly into the nuclei of cells has been demonstrated. This technique greatly increases the frequency of gene transfer and significantly expands the number of cell types that can be genetically transformed.

Animals↗