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J Dausset

Publications and source records attributed to J Dausset.

At least 73 records · Page 4Linked to original sources
PubMed1997

HLA-G gene transcriptional regulation in trophoblasts and blood cells: differential binding of nuclear factors to a regulatory element located 1.1 kb from exon 1.

The HLA-G antigen is specifically expressed on trophoblasts at the maternal-fetal interface, while expression of classical class I HLA-A, -B, -C products is repressed in this tissue. The transcriptional level of the HLA-G gene is high in trophoblast cells and in JEG-3 choriocarcinoma cells, is markedly reduced in blood cells, and is shown here to be undetectable in the YT2C2 NK cell line. In an attempt to understand molecular mechanisms controlling cell-specific transcriptional regulation of the HLA-G gene in these cells, we focused our study on protein interaction with a 244-bp region located over 1.1 kb from exon 1, which has been shown to direct HLA-G expression in transgenic mouse trophoblast. Three specific complexes were detected, two of which are found exclusively in cells showing HLA-G transcriptional activity. The YT2C2 nuclear extracts contain restricted DNA-binding activity of an additional factor which could correlate with repression of HLA-G transcription in these cells.

Exons↗
PubMed1997

[Fetomaternal tolerance: role of HLA-G molecule in the protection of the fetus against maternal natural killer activity].

HLA-G is a non-classical major histocompatibility complex class I molecule selectively expressed on extravillous trophoblast cells at the fetal-maternal interface. HLA-G may play an important role in maintaining maternal immune tolerance of the semi-allogenic fetus. In this study, we demonstrate for the first time the protective role of HLA-G during pregnancy. Indeed, cytotrophoblast cells of the fetus are resistant to lytic activity by maternal decidual natural killer cells. In order to precisely characterize the immunological functions of HLA-G products, we have investigated the protective role of the membrane-bound HLA-G1 and HLA-G2 isoforms against NK cell cytotoxicity. For this purpose, HLA-G1 and HLA-G2 cDNAs were transfected into the HLA-class I negative human K562 cell line. We demonstrate that both HLA-G1 and HLA-G2 transfectants inhibit NK cytolysis observed in peripheral blood from 25 donors (males and females). This led us to the conjecture that HLA-G is the public ligand for natural killer inhibitory receptors present in all individuals.

Cytotoxicity, Immunologic↗
PubMed1997

Search for DNA sequence variations using a MutS-based technology.

The search for DNA sequence variations (DSV) is emphasized with genetic studies of a large number of multifactorial diseases. Saturation of regions of interest with diallelic polymorphisms will be an essential step to pinpoint, through association studies, predisposing genes. We have developed a solid-phase method based on the ability of mismatch binding protein MutS to recognize single nucleotide mismatches. This approach was applied to the study of 83 sequence-tagged sites (STSs) extracted from an eight centimorgans (cM) chromosome 21 region. One-third of tested STSs were found to be polymorphic leading to a frequency of one DSV every 822 base pairs (bp). Sequencing of analyzed STSs showed the high reliability of the MutS-based technology for mismatches up to 2 bp in DNA fragments ranging in size from 200 bp to 1 kilobase (kb). The entire assay which is performed in a solid-phase format without the need of electrophoresis or sequencing, will provide an efficient tool for new polymorphism detection.

Adenosine Triphosphatases↗
PubMed1997

[Predictive medicine and its ethics].

The concept of predictive medicine based on the detection of genetic markers for disease susceptibility stemmed from the finding that many diseases are associated with specific HLA alleles. This model suggested that similar associations probably existed with other genes located all along the human genome. The Human Specimen Study Center (HSSC) was created to assist in investigating this possibility and has contributed significantly to the knowledge contained in current genetic and physical human genome maps. Predictive medicine is intended not for patients but for healthy individuals, its goal being to determine whether their susceptibility to a specific disease is increased or not. Fetuses with evidence of disease are excluded from the province of predictive medicine, which can, however, determine whether a healthy fetus is at high risk for developing a disease in adolescence or adulthood. Predictive medicine is based on probabilities: it evaluates diseases susceptibility but cannot predict with 100% certainty that a specific disease will occur. Whereas many preventive interventions are directed at groups (e.g., immunization programs), predictive medicine is conducted on an individualized basis. For instance, glaucoma is a monogenic disease whose early detection can allow to prevent permanent loss of vision. The fruits of predictive medicine are expected to be greatest, however, in the polygenic multifactorial diseases that are prevalent in industrialized countries, such as diabetes mellitus, hypertension, myocardial infarction, hyperlipidemia, and arteriosclerosis. An ability to detect subjects who are susceptible to breast cancer would be extraordinarily useful, and may be a goal within reach since two breast cancer susceptibility genes have already been identified. Genes associated with increased susceptibility to colon cancer have also been reported. Predictive medicine raises a number of sensitive ethical issues. Individuals should be free to accept or decline disease susceptibility testing after having been fully informed. Confidentiality is vital. The results of susceptibility tests should not be made available to employers or insurance agencies. Susceptibility testing should be offered only if the disease requires a specific treatment or lifestyle modification. Unnecessary anxiety may be one of the main adverse effects of susceptibility testing. A large number of disease susceptibility or resistance genes will probably be identified in the near future, and this will inevitably have an impact on the way physicians approach their patients. Physicians in the XXIst century will spend an increasingly large proportion of their time counselling their patients on how to stay healthy. This trend can be expected to translate into a marked increase in life expectancy. Rather than seeking to add years to life, physicians will strive to add life to years.

Confidentiality↗
PubMed1996

Activation of the human homologue of the Drosophila sina gene in apoptosis and tumor suppression.

Developmentally regulated genes in Drosophila, which are conserved through evolution, are potential candidates for key functions in biological processes such as cell cycle, programmed cell death, and cancer. We report cloning and characterization of the human homologue of the Drosophila seven in absentia gene (HUMSIAH), which codes for a 282 amino acids putative zinc finger protein. HUMSIAH is localized on human chromosome 16q12-q13. This gene is activated during the physiological program of cell death in the intestinal epithelium. Moreover, human cancer-derived cells selected for suppression of their tumorigenic phenotype exhibit constitutively elevated levels of HUMSIAH mRNA. A similar pattern of expression is also displayed by the p21waf1. These results suggest that mammalian seven in absentia gene, which is a target for activation by p53, may play a role in apoptosis and tumor suppression.

Amino Acid Sequence↗
PubMed1996

Predictive medicine.

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Disease Susceptibility↗
PubMed1996

HLA-G revisited.

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Female↗
PubMed1996

Survey of CAG/CTG repeats in human cDNAs representing new genes: candidates for inherited neurological disorders.

Expansion of polymorphic CAG and CTG repeats in transcripts is the cause of six inherited neurodegenerative or neuromuscular diseases and may be involved in several other genetic disorders of the central nervous system. To identify new candidate genes, we have undertaken a large-scale screening project for CAG and CTG repeats in human reference cDNAs. We screened 100 128 brain cDNAs by hybridization. We also scanned GenBank expressed sequence tags for the presence of long CAG/CTG repeats in the extremities of cDNAs from several human tissues. Of the selected clones, 286 were found to represent new genes, and 72 have thus far been shown to contain CAG/CTG repeats. Our data indicate that CAG/CTG repeated 10 or more times are more likely to be polymorphic, and that new 3'-directed cDNAs with such repeats are very rare (1/2862). Nine new cDNAs containing polymorphic (observed heterozygote frequency: 0.05-0.90) CAG/CTG repeats have been currently identified in cDNAs. All of the cDNAs have been assigned to chromosomes, and six of them could be mapped with YACs to 1q32-q41, 3p14, 4q28, 3p21 and 12q13.3, 13q13.1-q13.2, and 19q13.43. Three of these clones are highly polymorphic and represent the most likely candidate genes for inherited neurodegenerative diseases and, perhaps, neuropsychiatric disorders of multifactorial origin.

Brain↗
PubMed1995

Detection of membrane-bound HLA-G translated products with a specific monoclonal antibody.

A monomorphic anti-HLA-G monoclonal antibody (mAb) was obtained by immunization of HLA-B27/human beta 2-microglobulin double-transgenic mice with transfected murine L cells expressing both HLA-G and human beta 2-microglobulin. This mAb, designated BFL.1, specifically recognizes, by flow cytometry analysis, the immunizing HLA-G-expressing cells, whereas it does not bind to parental untransfected or to HLA-B7- and HLA-A3-transfected L cells, suggesting that it distinguishes between classical HLA-A and -B and nonclassical HLA-G class I molecules. This was further assessed by the absence of BFL.1 reactivity with a number of human cell lines known to express classical HLA class I proteins. In addition, we showed that the BFL.1 mAb also labels HLA-G-naturally-expressing JEG-3 and HLA-G-transfected JAR human choriocarcinoma cell lines as well as a subpopulation of first-trimester placental cytotrophoblast cells. Further biochemical studies were performed by immunoprecipitation of biotinylated membrane lysates: BFL.1, like the monomorphic W6/32 mAb, immunoprecipitated a 39-kDa protein in HLA-G-expressing cell lines, a size corresponding to the predicted full-length HLA-G1 isoform. However, in contrast to W6/32, which immunoprecipitates both classical and nonclassical HLA class I heavy chains, BFL.1 mAb does not recognize the class Ia products. Such a mAb should be a useful tool for analysis of HLA-G protein expression in various normal and pathological human tissues and for determination of the function(s) of translated HLA-G products.

Animals↗
PubMed1995

Evidence for the presence of the alternatively spliced HLA-G mRNA forms in human mononuclear cells from peripheral blood and umbilical cord blood.

The HLA-G monomorphic, nonclassic HLA class I gene encodes the molecule that is the only major histocompatibility complex antigen expressed on cytotrophoblasts of placenta. This restricted expression on fetal tissue that is in contact with maternal tissue suggests that HLA-G products may play a role in maternofetal tolerance. We previously have demonstrated in first-trimester human trophoblasts a new alternatively spliced form of HLA-G mRNA lacking exon 4 (HLA-G4) and weak expression of HLA-G1 copy mRNA in adult peripheral blood lymphocytes. By using exon-specific HLA-G primers, we demonstrate in this work the presence of three additional alternatively spliced forms of HLA-G mRNA in human peripheral mononuclear cells (HLA-G2, HLA-G3, and HLA-G4). In umbilical cord blood, HLA-G transcription was observed at very low level and only three alternatively spliced forms were detected (HLA-G1, HLA-G2, and HLA-G3). In contrast, we did not revealed any HLA-G transcript in CD34+ fraction of cord blood cells.

Alternative Splicing↗
PubMed1995

Soluble HLA-G molecule. An alternatively spliced HLA-G mRNA form candidate to encode it in peripheral blood mononuclear cells and human trophoblasts.

The HLA-G nonclassic MHC class I gene expressed at the maternal-fetal interface may be involved in cell protection against NK cell lysis. HLA-G mRNA is observed in different adult or fetal human cells and exhibits four alternative forms: HLA-G1, HLA-G2, HLA-G3, and HLA-G4 lacking, respectively, exon 7; exons 7 and 3, exons 7, 3, and 4; exons 7 and 4. Because exon 5 encodes the transmembrane domain of the HLA-G antigen, none of these transcripts could give a soluble form as detected in supernatant of trophoblasts. In this report, we describe an additional alternatively spliced for of HLA-G transcript (HLA-G5) present in adult PBMCs and first-trimester trophoblasts that contains intron 4. Moreover, as with all other transcripts, HLA-G5, is devoid of exon 7. Its relative frequency is, respectively, approximately 1:8 and approximately 1:26 in adult PBMCs and first-trimester trophoblasts. The presence of intron 4 generates a stop codon that excludes transmembrane region (exon 5) of the HLA-G molecule and therefore might produce a soluble antigen. These results are discussed with regard to data on soluble forms of classic HLA antigens and the possible role of HLA-G.

Alternative Splicing↗
PubMed1995

[Alternative transcripts of the MHC of the non-classical class I HLA-G gene in the in trophoblast during the first pregnancy trimester and in the placenta at term].

HLA-G, a non-classical class I gene, is located within the human major histocompatibility complex locus. It has a tissue-specific expression in trophoblast, where the products of HLA-A, -B and -C classical genes are absent. Therefore, the HLA-G gene may have a role during pregnancy in inducing protection of the semi-allogeneic fetus from recognition and destruction by maternal immune cells. The primary transcript of the HLA-G gene is alternatively spliced into 6 mRNA forms (HLA-G1 to HLA-G6), 2 of them may encode soluble forms of the HLA-G antigen (HLA-G5 and HLA-G6). In this work, by using reverse transcription polymerase chain reaction technique, we demonstrate that all transcripts are detected in similar amounts, both in the first and third trimester of gestation. These results are discussed in context of putative function of HLA-G antigen isoforms.

Alternative Splicing↗
PubMed1995

Natural killer cells are the unique lymphocyte cell subset which do not express HLA-G.

In order to better understand the immunological functions of the HLA-G gene, expression of this gene has been studied with RT-PCR in human functional lymphocyte subpopulations. Only one population of cells has not shown any HLA-G mRNA expression, the BY55-mAb-defined natural killer cells in cord blood. This absence of transcription was not modulated by IL2, IFN-gamma or TNF-alpha. Several T clone lymphocytes isolated from human peripheral blood, bone marrow or thymus have shown a significant transcription of the HLA-G gene. Only one clone, with a natural killer phenotype, did not reveal full length or alternatively spliced transcripts of HLA-G. Intensity of HLA-G transcription was not affected by TNF-alpha, IL13 or IL4, but HLA-G transcripts appeared more abundant in the presence than in the absence of IL2.

Fetal Blood↗
PubMed1994

BY55 monoclonal antibody delineates within human cord blood and bone marrow lymphocytes distinct cell subsets mediating cytotoxic activity.

We had previously reported, using BY55 monoclonal antibody, a cell surface 80-kDa protein restricted to human functional peripheral blood cytotoxic lymphocytes with either natural killer CD3- or cytotoxic T lymphocyte CD3+CD8+ phenotype. In the present report, we studied the cytotoxic lymphocytes in adult bone marrow and newborn cord blood as these organs are commonly used as sources of hematological stem cells for allogeneic transplantation. Our results showed that BY55 mAb labeled only 5-10% of the bone marrow lymphocytes, which included a major proportion of CD3+ CD8+ cytotoxic T lymphocytes. Interestingly, within cord blood cells, BY55+ lymphocytes represented 20-35% of the lymphocytes corresponding exclusively to a CD3- cell subset. Furthermore, we detected in cord blood no cytotoxic T lymphocyte activity but we demonstrated that the CD3-BY55+ cell subset contained the whole natural killer activity.

Antibodies, Monoclonal↗
PubMed1994

An alternatively spliced form of HLA-G mRNA in human trophoblasts and evidence for the presence of HLA-G transcript in adult lymphocytes.

The HLA-G monomorphic, nonclassical class I gene encodes the major histocompatibility complex (MHC) molecule, which is the only MHC antigen expressed on cytotrophoblast cells of placenta. In this work, we have investigated expression of the HLA-G gene in fetal tissues and adult peripheral blood cells by using a sensitive hot-start reverse transcriptase PCR technique. PCR amplification with HLA-G primers specific for exon 3 has enabled us to demonstrate an alternatively spliced form of HLA-G mRNA present in fetal first trimester trophoblasts and lacking exon 4 (HLA-G.3-5). This low abundance transcript (approximately 1:200) in comparison to full-length mRNA may encode the protein that excludes the alpha 3 domain and by conformational changes may present a different ability to bind to peptides. Moreover, expression of the HLA-G transcript was found in adult peripheral lymphocytes and equally in B- and T-cell populations. These results are discussed in the context of the fetal-maternal relationship presented by HLA-G gene products.

Adult↗