Biomedical subjects

G Corte

Publications and source records attributed to G Corte.

At least 37 records · Page 2Linked to original sources

PubMed1997

Mapping of a potent transcriptional repression region of the human homeodomain protein EVX1.

The human homeodomain protein EVX1 is a transcriptional repressor in transfected mammalian cells and this function depends on a region carboxyl-terminal to the homeodomain. In this study, we transiently expressed several deletions of the EVX1 C-terminal region in mammalian cells and investigated their effect on the transcription of a reporter gene directed by different promoters. We show that the repressor activity maps to a region of 51 amino acids with a high abundance of alanine and proline residues. This region is able to transfer the repressor function to either the entire HOXC6 or CREB transcription factors, or to the GAL4 DNA binding domain.

3T3 Cells↗

PubMed1997

The human homeodomain protein OTX2 binds to the human tenascin-C promoter and trans-represses its activity in transfected cells.

Homeodomain-containing proteins mediate many transcriptional processes in eukaryotes during development. Recently, mammalian homeodomain proteins involved in the anterior head formation have been discovered, but their effect on gene transcription has never been investigated. Here we report on the ability of the human homeodomain protein OTX2 to bind with high affinity to a target sequence present in the promoter of the gene encoding the human extracellular matrix protein tenascin-C and to repress its transcriptional activity in transiently transfected cells.

Animals↗

PubMed1996

Expression of HOXC4, HOXC5, and HOXC6 in human lymphoid cell lines, leukemias, and benign and malignant lymphoid tissue.

Besides their regulatory role in embryogenesis, homeobox (HOX) genes are expressed in a specific manner in hematopoietic cell lineages, implying a role in the molecular regulation of hematopoiesis. Some HOX C cluster genes are found to be expressed in lymphoid cells of mice and humans. Their function and expression in normal hematopoiesis are still largely unknown. We have studied the mRNA expression of HOXC4, HOXC5, and HOXC6 in several stages of lymphocyte maturation by reverse transcriptase-polymerase chain reaction (RT-PCR) and RNA in situ hybridization (RISH). We examined CD34+/CD38low and CD34+/CD38high cells obtained from normal donor bone marrow (BM), a panel of 19 lymphoid cell lines, several types of leukemias and non-Hodgkin's lymphomas (NHL), and lymphocytes isolated from tonsillar tissue and peripheral blood (PB). HOXC4 and HOXC6 were found to be expressed during maturation in B- and T-lymphoid cells. The expression of each gene was found to be initiated at different cell maturation stages. HOXC4 transcripts were present in CD34+/CD38low cells, which are thought to comprise stem cells and noncommitted progenitor cells, and in subsequent stages to terminally maturated lymphoid cells. HOXC6 expression is initiated in equivalents of prothymocyte and pre-pre-B cell stage and remains present in mature cells. However, HOXC5 is only expressed in neoplastic cell lines and in neoplastic cells of NHL, but not in CD34+ BM cells, nor in resting or activated lymphoid cells isolated from tonsil, PB, or in leukemia cells. In cell lines, weak expression of HOXC5 is initiated in equivalents of pre-B cell and common thymocyte stage and is continuously expressed in mature cell lines. Semi-quantitative RT-PCR showed that expression levels of HOXC5 were much lower than those of HOXC4 and HOXC6; furthermore an increase of expression of HOXC4, HOXC5, and HOXC6 during lymphoid cell differentiation was demonstrated. Thus, mainly mature lymphoid cell lines and neoplastic cells of NHL do express HOXC5, in contrast to the lack of expression in normal lymphoid cells and leukemias. These findings suggest involvement of HOXC5 in lymphomagenesis.

Base Sequence↗

PubMed1996

EMX1 homeoprotein is expressed in cell nuclei of the developing cerebral cortex and in the axons of the olfactory sensory neurons.

We analyzed the distribution of EMX1 during mouse development. EMX1 is a homeoprotein encoded by Emx1, a regulatory homeobox gene expressed in the developing forebrain. Its distribution essentially overlaps the expression domains of Emx1 transcripts. The EMX1 protein is present in the developing dorsa telencephalon, that is in the cerebral cortex, olfactory bulb and hippocampus. In the cerebral cortex EMX1 is present in nuclei of proliferating, differentiating and most mature neurons belonging to all cortical layers. In the olfactory bulb it is present in all proliferating cells during development, whereas postnatally it is faintly expressed in some mitral cells. Non-cerebral localizations include a transient expression in branchial pouches, in the apical ectodermal ridge of the developing limbs and in the developing kidney. Of particular interest is the presence of EMX1 in the olfactory nerve from its first appearance during embryogenesis to birth. The protein is present in axons of olfactory sensory neurons along their entire length, including their terminals in spherical regions of neuropil in the olfactory bulb called glomeruli.

Animals↗

PubMed1996

OTX2 homeoprotein in the developing central nervous system and migratory cells of the olfactory area.

We analyzed the distribution of OTX2 during mouse development. OTX2 is a homeoprotein encoded by Otx2, a vertebrate homeobox gene expressed in the developing brain and anterior head regions. The protein is already detectable in pre-streak embryos, in nuclei of embryonic ectoderm or epiblast and primitive endoderm or hypoblast. Its distribution is uniform along the entire epiblast, while showing an antero-posterior gradient along the hypoblast at the time when primitive streak first forms. Between embryonic day 7 (E7) and E7.5 there is a progressive confinement of the protein to the anterior ectoderm corresponding to the forming headfold. At E7.5-E7.8, the protein is mainly confined in this region but is still present, though at lower level, in more posterior ectoderm. Starting from day 8 of development it is essentially confined to anterior neuroectoderm corresponding to presumptive fore- and midbrain. Its subsequent distribution in forebrain, midbrain, developing isthmo-cerebellum and posterior central nervous system is analyzed in detail. Of particular interest is the presence of OTX2 in nuclei of cells of the olfactory system starting from its origin in the olfactory placode. OTX2 protein is present in some cells of the olfactory epithelium, in both the major olfactory epithelium and the vomero-nasal organ, and in scattered migratory cells present in the mesenchyme outside it. These cells surround the axon bundles of the olfactory nerve along its path from the olfactory epithelium in the nasal cavities to the olfactory bulb in rostral telencephalon and include both ensheathing glial cells and luteinizing hormone-releasing hormone (LHRH)-positive cells.

Age Factors↗

PubMed1995

Transcriptional repression by the human homeobox protein EVX1 in transfected mammalian cells.

The human homeobox protein EVX1 (EVX1) is thought to play an important role during embryogenesis. In this study, the effect of EVX1 on gene transcription has been investigated in transfected mammalian cells. EVX1 expression represses transcription of a reporter gene directed by either cell-specific or viral promoter/enhancer sequences in a variety of mammalian cell lines and in a concentration-dependent manner. Transcriptional repression is independent of the presence of DNA-binding sites for EVX1 in all the promoters we tested. Furthermore, repression by EVX1 is evident also using a TATA-less minimal promoter in the reporter construct. A carboxyl-terminal proline/alanine-rich region of EVX1 seems to be responsible for the transcriptional repression activity, as suggested by transfection of EVX1 mutants. We speculate that the repressor function of EVX1 contributes to its proposed role in embryogenesis.

Animals↗

PubMed1995

Expression of HOXC4 homeoprotein in the nucleus of activated human lymphocytes.

We have analyzed the expression of homeoproteins of the HOX family in resting and activated lymphoid cells and in neoplastic lymphoid cell lines by the use of monoclonal antibodies (MoAbs) already shown to react with the homeoproteins HOXA10, HOXC6, and HOXD4, respectively. Anti-HOXA10 and C6 MoAbs DIDi not show any reactivity with the lymphoid cells tested, whereas anti-HOXD4 MoAb stained few resting peripheral blood lymphocytes (PBLs) and most phytohemagglutinin (PHA)-stimulated PBLs as early as 6 hours after stimulation. The pattern of staining of PHA-activated PBLs is reminiscent of the stages of nucleolar fragmentation in different phases of the cell cycle. The MoAb reacted also with activated or Epstein-Barr virus-transformed B cells, with clonal or polyclonal T and natural killer (NK) cells, with leukemic T-cell lines, and with a Burkitt's lymphoma cell line. RNAse protection experiments, per formed with probes specific for HOXD4 or for the highly homologous HOXA4, HOXB4, and HOXC4, belonging to the same paralogy group, indicated that only HOXC4 mRNA is present in resting or activated PBLs. Northern blot analysis on polyA+ RNA from activated PBLs or Raji cells showed the presence of two different HOXC4 transcripts of 2.8 and 1.9 kb. Gel retardation and Southwestern blot assays showed the presence of a 32-kD homeoprotein with DNA-binding properties typical of a HOX4 homeoprotein in nucleolar extracts of PHA-activated, but not of resting, lymphocytes. Taken together, these data indicate that the HOXC4 homeoprotein is expressed in activated and/or proliferating lymphocytes of the T-, B-, or NK-cell lineage, whereas it is weakly expressed in a minority of resting cells. The early expression and the nucleolar localization suggest an involvement of HOXC4 in the regulation of genes controlling lymphocyte activation and/or proliferation.

Antibodies, Monoclonal↗

PubMed1995

Expression of a novel beta 1 integrin in the dysplastic progression of the cervical epithelium.

Epithelial cell interactions with matrices and basal membranes are central for tissue organization, and integrins are a family of adhesion molecules that play a major role in these interactions. We have analyzed the expression of a novel integrin alpha chain, alpha 10.1.2, in the squamous epithelium of the portio vaginalis uteri from patients with cervical intraepithelial neoplasia (CIN) and from control samples without apparent cervical abnormalities. The localization of beta 1 and alpha 6 chains was also investigated, together with the distribution of intraepithelial HLA-DR and CD1c-positive Langerhans cells. In the normal cervical epithelium, all of the integrin chains were detected in the basal cell layer, albeit with a different localization in the apical, lateral, and basal cell surfaces. Langerhans cells were evenly distributed in the deep 2/3 of the squamous epithelium. Expression of alpha 10.1.2 was reduced or absent in all of the CIN 1 specimens in which the other integrin chains were either normal or slightly reduced. CIN 2 was characterized by overexpression of integrins, namely of beta 1 and of alpha 10.1.2 chains which were consistently detected also in suprabasal cell layers. None of the integrin chains was found in CIN3 samples in which Langerhans cells were also absent. Thus, modulation and redistribution of integrins occur in the progression of cervical dysplasia, and lack of integrin expression characterizes high-grade lesions. As in other dysplasias and cancers of squamous epithelia, the localization of alpha 10.1.2 chains provides reliable diagnostic and possibly prognostic criteria.

Adult↗

PubMed1995

Nucleolar localisation of three Hox homeoproteins.

Homeoproteins encoded by genes of the Hox family are nuclear proteins believed to act as transcription factors and to participate in the determination of the body plan. Here we show that in several vertebrate cells, they exhibit a subnuclear localisation associated with the nucleolus. We used monoclonal antibodies to study the distribution of three homeoproteins, namely HOXB7, HOXC6 and HOXD4. The immunoreactivity to antibodies against HOXC6 protein in Xenopus laevis embryonic tissues is restricted to one or two spots within the nucleus; this distribution partially overlaps that of fibrillarin, a protein of the fibrillar zone of the nucleoli. Indirect immunofluorescence analysis of the distribution of HOXB7 protein in 3T3 cells, and of HOXD4 protein in human neuroblastoma and Raji lymphoma cell lines and activated lymphocytes, results invariably in a nucleolar localisation. Purified nucleoli from stimulated T lymphocytes, and Raji cells contain an activity capable of binding, in a gel retardation assay, to an oligonucleotide specifically recognised by the HOXD4 homeoprotein. This activity is specifically removed by anti-HOXD4 antibodies and is found associated in southwestern blots with a single band with an apparent M(r) of 30,000, corresponding to that of recombinant HOXD4. The functional significance of the nucleolar localisation of Hox proteins remains to be determined.

Animals↗

PubMed1994

Immunohistochemical localization of a novel beta 1 integrin in normal and pathologic squamous epithelia.

The 10.1.2 MoAb reacts with a novel alpha chain that associates with the beta 1 integrin chain and is widely distributed among epithelial and endothelial cells of human adult and fetal tissues. In the epidermis and in other squamous epithelia, alpha 10.1.2 chains are expressed exclusively in the basal cell layer. Here we describe the immunohistochemical localization of alpha 10.1.2 in human epidermis, in other squamous epithelia, as well as in cultured keratinocytes. alpha 10.1.2 chain localization has also been investigated in a variety of non-neoplastic and neoplastic lesions of the skin, the uterine cervix, and the lung. We show that alpha 10.1.2 chains retain their basal keratinocyte localization in hyperplastic skin diseases and in benign tumors of the epidermis and that they are strongly expressed in basal cell carcinomas. In contrast, alpha 10.1.2 expression is decreased in keratinocytes that differentiate in vitro and is lost in epidermal dysplastic conditions, in the invading front of squamous cell carcinomas of the epidermis, in microinvasive cervical cancers, and in well-differentiated squamous lung tumors. These findings indicate that alpha 10.1.2 beta 1 integrin is downregulated during keratinocyte differentiation in vitro and in vivo. Moreover, lack of alpha 10.1.2 expression in basal cells of squamous epithelia is associated with early dysplastic changes and with the acquisition of invasive capacity.

Antibodies, Monoclonal↗

PubMed1993

Changes in the prevalence of an homeobox gene product during muscle differentiation.

We have studied by immunohistofluorescence and confocal microscopy the localization of the XlHbox-1 protein, the product of a Xenopus class 1 homeobox gene corresponding to the human HOX 3C, during the development of Xenopus laevis mesodermal derivatives. The protein, not present at early stages of embryonic development, can first be detected in the neurula where it is weakly expressed in the rostral part of the spinal cord and in the nuclei of the corresponding somites. At later stages of mesodermal development, very high levels of the molecule are present in the nuclei of a small group of myogenic cells in the most dorsal aspect of the myotome, while the nuclei of differentiated muscle fibers within the myotome are either stained weakly or completely negative. A similar transient expression of XlHbox-1 gene product during myogenesis occurs during muscle differentiation in the limb bud and during differentiation of visceral smooth muscles from the lateral plate mesoderm. In both cases the nuclei of precursor cells contain high level of this protein which is rapidly down regulated during further muscle differentiation. In myogenic areas the modulation of XlHbox-1 expression invariably parallels that of the neural cell adhesion molecule N-CAM. These data are the first evidence that a homeobox gene belonging to the Antennapedia-Bithorax complex is transiently expressed in early phases of muscle differentiation. The transient expression of homeobox genes in early phases of embryonic development could act synergistically with the expression of other myogenic transcriptional factors to specify a fine level of differentiation of the muscle cells along the body axis.

Animals↗

PubMed1993

Antibody binding profile of purified and cell-bound CD26. Designation of BT5/9 and TA5.9 to the CD26 cluster.

The CD26 activation antigen (Ag) which is expressed on a subpopulation of human T cells has been characterized as dipeptidyl peptidase IV (DPP IV, EC 3.4.14.5). In this paper, we describe the antibody binding profile of CD26/DPP IV, purified from human peripheral blood lymphocytes. The purified molecule binds to the anti-Ta1, anti-1F7 and anti-134-2C2 monoclonal antibodies (mAb), reported to react with cell-bound CD26 Ag. Among unclustered mAb recognizing T cell antigens, two, anti-BT5/9 and anti-TA5.9 were found to react with purified and cell-bound CD26 Ag. The classification of the BT5/9 Ag, the functional properties of the BT5/9+ T cell subset, as well as the in vivo effect of anti-BT5/9 mAb administration, are re-interpreted in the light of its specificity. Applying the anti-TA5.9 mAb in three color FACS analyses, we demonstrated that CD26+bright cells co-express CD45RO but not HLA-DR and CD38.

Antibodies, Monoclonal↗

PubMed1993

The homeotic gene products in the control of cell differentiation and proliferation.

Embryo development is controlled by a successive series of genes that provide each cell in the growing embryo with precise position information. Knowledge of these genes is known most completely from Drosophila, where a simple initial pattern generated by maternal effect genes is gradually segmented by the sequential transient expression of three successive series of genes: the gap genes, the pair-rule genes, and the segment polarity genes. Superimposing their action on the preexisting segments, these homeotic genes cause unique and often very distinctive patterns of differentiation for different segments. In humans, about 40 homeotic genes have been identified and are grouped into four clusters on chromosomes 2, 7, 12, and 17, whose organization reflects their spatial and temporal expression. Several homeotic genes have been found expressed not only in embryonic tissues, but also in adult tissues, most notably in the hematopoietic lineage, and also in tumors, especially leukemia, teratocarcinoma, and neuroblastoma, wherein their expression pattern is modified in a complex manner by retinoic acid. The target genes of the transcription factors encoded by the homeotic genes are largely unknown, but recent reports indicate that they may regulate the expression of adhesion molecules on the membrane and the production of components of the extracellular matrix. Abnormal expression of these genes can therefore affect not only cell proliferation, but also the spread of cells to aberrant locations.

Animals↗

PubMed1992

Differential DNA binding properties of three human homeodomain proteins.

The products of three human homeobox containing (HOX) genes, 2C, 3C and 4B, were produced in insect cells using the Baculovirus expression system and purified to near homogeneity. In this system we observed that the DNA binding forms of the three proteins are not glycosylated. HOX 3C and 4B are phosphorylated in insect cells, while HOX 2C is not. The three HOX proteins bind to a DNA sequence known to be a target site for Antennapedia protein with a very similar affinity (Kd = 1-2 x 10(-9) M). We then measured their binding properties to four human sequences present in the HOX 3D, 4C, 1C and 4B promoters. Two of these sequences have been reported to be binding sites for HOX proteins. HOX 2C, 3C and 4B behaved quite differently, showing low affinity for promoters of genes located upstream from their own gene in the HOX clusters and a higher affinity for regulatory sequences of their own gene and downstream HOX genes.

Animals↗

PubMed1992

Localization of a novel integrin of the beta 1 subfamily in human tissues.

We have previously described a novel integrin composed of a beta 1-chain non-covalently linked to an alpha-chain which is biochemically different from those known so far (i.e., alpha 1-alpha 7 and alpha v). This molecule has been identified with a monoclonal antibody (MAb) termed 10.1.2 raised against long-term cultured human thymic epithelial cells (TEC). In this study we analyzed the immunohistochemical distribution of this new integrin in a variety of human tissues. MAb 10.1.2 stains several types of endothelial and epithelial cells. Among the endothelia, a strong reaction was detected in the HEV of lymphoid organs including thymus, lymph node, tonsil, and mucosa-associated lymphoid tissue. Epithelial localizations of note were those in the basal layer of the epidermis and of other stratified squamous epithelia, where the lateral and apical but not the deep surfaces of most cells were stained. A variety of water-electrolyte transporting cells in sweat glands, salivary glands, and kidney were also stained at their deep surface. The latter findings suggest that this molecule may subserve other functions in addition to those related to cell adhesion.

Adult↗

PubMed1991

A novel integrin involved in thymocyte-thymic epithelial cell interactions.

Thymocytes differentiate in the thymic microenvironment into immunocompetent T cell through the interaction with a variety of accessory cells, including thymic epithelial cells (TEC). TEC plays an important role in the selection process presenting self antigens in association with major histocompatibility complex (MHC) molecules to the maturing T cells. The T cell receptor recognizes the self antigen-MHC complex, but other surface molecules help stabilize this interaction. Thus, the CD2/LFA-3 and LFA-1/intercellular adhesion molecule 1 pairs have been shown to participate in the binding between lymphoid cells and TEC. Here we describe an integrin of the very late activation antigen subfamily composed by the known beta 1 chain and by a novel alpha chain. This adhesion molecule is expressed on the surface of medullary TEC and is involved in the adhesion between TEC and thymocytes, but not peripheral blood T lymphocytes.

Antibodies, Monoclonal↗

PubMed1990

Use of three DNA polymorphisms of the LDL receptor gene in the diagnosis of familial hypercholesterolemia.

Familial hypercholesterolemia (FH) is an autosomal dominant metabolic disorder caused by several different mutations in the low density lipoprotein (LDL) receptor gene. This large number of different mutations, often undetectable in Southern blotting, makes it impossible directly to diagnose the disease. However, restriction fragment length polymorphisms (RFLPs) can be used to follow the inheritance of the defective gene in FH families. In the present study, we report the use of three RFLPs, detected by PvuII, ApaLI and AvaII restriction enzymes, to determine the haplotypes of normal and defective LDL receptor genes in 61 families with FH and in 128 normal individuals. Two of the nine haplotypes were significantly more often associated with the affected genes, whereas one was significantly less frequent. Although none of the associations was strong enough to allow diagnosis in individuals, it was possible, using the three RFLPs, to identify the haplotype of the affected gene in 57 families and to carry out unequivocal diagnosis in 67% of the cases. In four families, PvuII and AvaII detected an abnormal fragment co-segregating with the disease, thus increasing the percentage of diagnosis to 73.4% of the cases.

Alleles↗

PubMed1990

Human ciliated bronchial epithelial cells: expression of the HLA-DR antigens and of the HLA-DR alpha gene, modulation of the HLA-DR antigens by gamma-interferon and antigen-presenting function in the mixed leukocyte reaction.

HLA-DR class II molecules are expressed by a variety of nonlymphoid cells, including the respiratory epithelium. However, it is not known if ciliated bronchial epithelial cells express the HLA-DR genes, if the expression of class II molecules on their surface can be modulated by immune mediators and, finally, if these cells, like other HLA-DR-positive epithelial cells, have the potential to serve as antigen-presenting cells. To answer these questions, we collected ciliated bronchial epithelial cells by brushing and by suction during fiberoptic bronchoscopy and by scraping surgically resected bronchi. The number of cells recovered by brushing or suction during fiberoptic bronchoscopy was similar (P greater than 0.2), but lower than that obtained by scraping surgically resected bronchi (P less than 0.01); however, compared with brushing, suction of ciliated bronchial epithelial cells resulted in a better viability (P less than 0.05). HLA-DR antigens on ciliated bronchial epithelial cells were detected by immunofluorescence using the PTF 29.12 and the L243 monoclonal antibodies, both recognizing HLA-DR molecules on the vast majority of ciliated bronchial epithelial cells. Cytoplasmic dot blot analysis demonstrated that ciliated bronchial epithelial cells had mRNA HLA-DR transcripts, and Northern blot hybridizations showed that the size of the HLA-DR messages was the same observed in other HLA-DR-positive cells. Interestingly, ciliated bronchial epithelial cells showed a significant decline of HLA-DR expression after 5 days in culture, but the addition of gamma-interferon to the cell cultures was associated with the persistence of the expression of class II antigens on the cell surface (P less than 0.01 with control cultures at 5 days). Finally, while ciliated bronchial epithelial cells were ineffective in stimulating allogeneic T cell proliferation in a 6-day primary mixed leukocyte reaction (MLR), the addition of phorbol myristate acetate to the MLR was able to induce a significant T cell proliferation (P less than 0.001, all comparisons). Thus, human ciliated bronchial epithelial cells express HLA-DR surface antigens and have mRNA molecules for the HLA-DR genes, and the expression of the surface class II antigens can be modulated in vitro by immune mediators.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗