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Biomedical subjects

F Costantini

Publications and source records attributed to F Costantini.

At least 109 records · Page 6Linked to original sources
PubMed1989

Silent genes in the mouse major urinary protein gene family.

To date, two classes of mouse major urinary protein (MUP)-encoding genes have been described, the expressed genes and the intervening-sequence-containing pseudogenes. The data presented in this paper define a third class, the silent Mup genes, which are potentially functional but appear not to be expressed under normal circumstances. We describe a MUP subfamily (Mup-1.5) containing two genes, Mup-1.5a and Mup-1.5b, that are nearly identical, differing at only three positions (greater than 99.9% identity) over the entire 4-kilobase (kb) transcription unit and approximately 1 kb of flanking DNA. The similarity between these two genes extends over greater than 35 kb. Using specific oligonucleotides, we have shown that the 5a gene is expressed in BALB/cByJ mice, primarily in the submaxillary gland, whereas the 5b gene is not expressed. However, we found that when a 9.4-kb DNA fragment containing the Mup-1.5b gene was introduced into the mouse germ line, mice in two of the four transgenic lines expressed this gene at a high level and with the tissue-specificity characteristic of the Mup-1.5a gene. These results suggest that the inactivity of the endogenous Mup-1.5b gene is due not to a lack of functional positive regulatory elements, but to long-range, inhibitory position effects.

Animals↗
PubMed1989

Beta-globin enhancers target expression of a heterologous gene to erythroid tissues of transgenic mice.

To examine the role of human beta-globin enhancers in tissue-specific and developmental regulation, a hybrid beta-globin-simian virus 40 gene was analyzed in transgenic mice. A beta-globin DNA fragment containing two previously defined enhancers stimulated transcription from the simian virus 40 promoter in a tissue- and stage-specific pattern similar to that of the normal beta-globin gene. These results help to define the functions of beta-globin regulatory elements and suggest an approach for targeted expression of heterologous genes in erythroid cells in vivo.

Aging↗
PubMed1988

Malaria in beta-thalassemic mice and the effects of the transgenic human beta-globin gene and splenectomy.

To investigate the protective effects of beta-thalassemia against malaria, rodent malaria parasites were studied in C57BL/6J mice with beta-thalassemia, in mice in which the thalassemia had been transgenically corrected with the human beta A-globin gene, and in hematologically normal mice. In thalassemic mice, Plasmodium chabaudi adami infection was inhibited and peak parasitemia was variably delayed. In transgenically corrected mice, infection proceeded as in normal mice. Plasmodium berghei infection proceeded more rapidly in thalassemic mice, but survival was not different. Splenectomized normal mice displayed high-level parasitemia that peaked twice and persisted as a low-level parasitemia for more than 20 days after normal intact mice were free of all parasites. Splenectomized thalassemic mice showed a delay of 5 days in attaining peak parasitemia, but the parasitemia persisted as in normal splenectomized mice. Thus, for P. chabaudi, which displayed no preference for immature erythrocytes, beta-thalassemia offers enhanced resistance for the host. However, for P. berghei, which preferentially invades reticulocytes, thalassemia is not protective. The protective effects of the normal mouse spleen were observed, but the paradoxical facilitation of parasite growth by the thalassemic spleen is a new finding that will require further experimentation to explain. This new in vivo laboratory documentation of thalassemic protection against some rodent malaria parasites may serve as a useful model in further efforts to control this major infectious disease.

Animals↗
PubMed1987

A 3' enhancer contributes to the stage-specific expression of the human beta-globin gene.

The human beta-globin and G gamma-globin genes are expressed at different stages of human development and also show distinct temporal patterns of expression when transferred into the mouse germ line. In transgenic mice, the beta-globin gene is expressed only in fetal and adult erythroid cells, whereas the G gamma-globin gene is active only in embryonic erythroid cells. Previous experiments suggested that beta-globin 3' sequences were important for expression in mouse fetal and adult erythroid cells, and in this paper we directly demonstrate the presence of an enhancer in the 3'-flanking region of the gene. First, deletion of sequences between 605 and 895 bp, 3' to the poly(A) site, results in a 10-fold reduction in the average level of expression of the beta-globin gene in transgenic mouse fetal livers. Second, a DNA fragment including beta-globin 3'-flanking sequences [425-1480 bp from the poly(A) site], in either orientation, activates transcription from the otherwise silent G gamma-globin promoter in the mouse fetal liver; DNA sequences between 150 and 730 bp or between 920 and 1680 bp, 3' to the beta-globin gene, are inactive by this assay. Together, these experiments identify an enhancer, in the region approximately 600-900 bp, 3' to the beta-globin poly(A) site, which contributes to the differential stage-specific expression of the beta-globin and G gamma-globin genes.

Animals↗
PubMed1987

Tissue-specific and hormonally regulated expression of a rat alpha 2u globulin gene in transgenic mice.

To investigate the tissue-specific and hormonal regulation of the rat alpha 2u globulin gene family, we introduced one cloned member of the gene family into the mouse germ line and studied its expression in the resulting transgenic mice. Alpha 2u globulingene 207 was microinjected on a 7-kilobase DNA fragment, and four transgenic lines were analyzed. The transgene was expressed at very high levels, specifically in the liver and the preputial gland of adult male mice. The expression in male liver was first detected at puberty, and no expression was detected in female transgenic mice. This pattern of expression is similar to the expression of endogenous alpha 2u globulin genes in the rat but differs from the expression of the homologous mouse major urinary protein (MUP) gene family in that MUPs are synthesized in female liver and not in the male preputial gland. We conclude that these differences between rat alpha 2u globulin and mouse MUP gene expression are due to evolutionary differences in cis-acting regulatory elements. The expression of the alpha 2u globulin transgene in the liver was abolished by castration and fully restored after testosterone replacement. The expression could also be induced in the livers of female mice by treatment with either testosterone or dexamethasone, following ovariectomy and adrenalectomy. Therefore, the cis-acting elements responsible for regulation by these two hormones, as well as those responsible for tissue-specific expression, are closely linked to the alpha 2u globulin gene.

Age Factors↗
PubMed1987

Upstream G gamma-globin and downstream beta-globin sequences required for stage-specific expression in transgenic mice.

The human G gamma-globin and beta-globin genes are expressed in erythroid cells at different stages of human development, and previous studies have shown that the two cloned genes are also expressed in a differential stage-specific manner in transgenic mice. The G gamma-globin gene is expressed only in murine embryonic erythroid cells, while the beta-globin gene is active only at the fetal and adult stages. In this study, we analyzed transgenic mice carrying a series of hybrid genes in which different upstream, intragenic, or downstream sequences were contributed by the beta-globin or G gamma-globin gene. We found that hybrid 5'G gamma/3'beta globin genes containing G gamma-globin sequences upstream from the initiation codon were expressed in embryonic erythroid cells at levels similar to those of an intact G gamma-globin transgene. In contrast, beta-globin upstream sequences were insufficient for expression of 5'beta/3'G gamma hybrid globin genes or a beta-globin-metallothionein fusion gene in adult erythroid cells. However, beta-globin downstream sequences, including 212 base pairs of exon III and 1,900 base pairs of 3'-flanking DNA, were able to activate a 5'G gamma/3'beta hybrid globin gene in fetal and adult erythroid cells. These experiments suggest that positive regulatory elements upstream from the G gamma-globin and downstream from the beta-globin gene are involved in the differential expression of the two genes during development.

Animals↗
PubMed1986

Tissue-specific DNase I hypersensitive sites in a foreign globin gene in transgenic mice.

We have investigated the DNase I hypersensitivity of a hybrid mouse/human beta-globin gene in erythroid and non-erythroid cells of transgenic mice, to examine the relationship between the chromatin structure and the expression of an exogenous gene. The hybrid globin gene was previously shown to be expressed specifically in erythroid cells in some transgenic lines. The maximal level of hybrid globin mRNA accumulation was a few percent of the endogenous level, and we show here that this results from a low rate of transcription. In erythroid cells from two transgenic lines in which the hybrid gene is expressed, we detect a set of DNase I hypersensitive sites whose locations are indistinguishable from those in endogenous beta-globin genes. The hybrid globin gene contains no DNase I hypersensitive sites in transgenic mouse brain cells. Thus, the tissue-specific expression of the exogenous globin gene is reflected in, and perhaps mediated by, tissue-specific changes in chromatin structure.

Animals↗
PubMed1986

Correction of murine beta-thalassemia by gene transfer into the germ line.

A murine beta-thalassemia was corrected by the transfer of cloned beta-globin genes into the mouse germ line. The cloned mouse beta maj-globin gene or the cloned human beta-globin gene was introduced into mice deficient in beta-globin synthesis because of a deletion of the beta maj-globin gene. Both introduced genes produced functional beta-globin chains, leading to a reduction in one case, and elimination in another case, of the anemia and associated abnormalities of the red blood cells.

Animals↗
PubMed1986

Altered repertoire of endogenous immunoglobulin gene expression in transgenic mice containing a rearranged mu heavy chain gene.

C57BL/6 mice transgenic for a mu heavy chain gene, the VDJ region of which came from the BALB/c hybridoma 17.2.25, expressed high levels of antibody carrying determinants specific for the transgene (idiotypes). The individual antibodies made by hybridomas from transgenic mice, however, were generally encoded by endogenous genes; in most cases the transgene was present but not expressed. The endogenous, idiotype-positive antibodies had heavy chains that were notable for the high frequencies of JH4 (as in the transgene) and VH segments from the VH81X family (unrelated to the transgene). The expression of endogenous genes mimicking the idiotype of the transgene suggests that a rearranged gene introduced into the germ line can activate powerful cellular regulatory influences.

Animals↗
PubMed1985

A transgenic immunoglobulin mu gene prevents rearrangement of endogenous genes.

Transgenic mice containing a microinjected rearranged immunoglobulin (Ig) mu heavy chain gene were examined for the effects on DNA rearrangement of the endogenous Ig genes. Abelson murine leukemia virus (A-MuLV) cell lines were isolated from pre-B cells of transgenic mice and of normal littermates. Microinjected mu gene RNA and a mu heavy chain protein were synthesized in every transgenic A-MuLV cell line. Only 10% of normal mouse A-MuLV transformants synthesized mu protein. A germ-line JH allele was observed in 40% of the transgenic lines, demonstrating that the block to endogenous Ig DNA rearrangement occurred at the first step of heavy chain DNA joining. All alleles were rearranged in normal mouse A-MuLV lines. Germline JH alleles were also detected in 10% of the transgenic hybridomas derived from proliferating B cells. Our results support a model of active prevention of rearrangement by the product of successfully rearranged mu genes.

Abelson murine leukemia virus↗
PubMed1984

Introduction of a mu immunoglobulin gene into the mouse germ line: specific expression in lymphoid cells and synthesis of functional antibody.

A functionally rearranged mu heavy chain immunoglobulin (lg) gene was introduced into the germ line of mice. The mu gene encodes a polypeptide which, combined with lambda 1 light chains, shows a specificity for binding the hapten NP. Four transgenic mice harboring 20-140 copies of the foreign mu gene expressed the gene specifically in spleen, lymph node, and thymus at a high level. Purified surface lg-positive B cells, Lyt 2-positive mature T cells, and thymocytes transcribed the foreign mu gene at a similarly high level, suggesting that control of lg gene rearrangement might be the only mechanism that determines the specificity of heavy chain gene expression within the lymphoid cell lineage. No transcription of the foreign mu gene was detected in nonlymphoid tissues with the exception of the heart which expressed the gene at a low level. The transgenic mice had up to 400-fold elevated serum levels of NP binding antibody, which contained a heavy chain with the characteristics of the foreign mu gene. The serum levels of endogenous heavy and light chains in transgenic mice appeared to be the same as in normal mice.

Animals↗