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Biomedical subjects

F Costantini

Publications and source records attributed to F Costantini.

114 records · Page 7Linked to original sources
PubMed1982

Gene transfer into the mouse germ-line.

A cloned rabbit DNA fragment containing the adult beta-globin gene has been introduced into the mouse germ-line by DNA microinjection into the pronuclei of fertilized mouse eggs. Twenty-four adult mice derived from eggs injected with the cloned DNA were screened for the presence of the rabbit gene in their liver DNA by Southern blot hybridization. Nine of these mice contain the rabbit gene in liver and at least six of them transmit it through the germ-line to a fraction of their offspring. Thus, it should be possible to derive permanent strains of mice carrying the foreign gene. The estimated numbers of copies of the rabbit gene per diploid mouse genome range from one or two up to 20 or more. The multiple copies of the rabbit DNA clone appear to be arranged in tandem head-to-tail arrays that are integrated into mouse chromosomal DNA. Chromosomal integration has been directly demonstrated for one mouse by in situ hybridization to metaphase chromosomes using a radioiodinated probe. In this mouse, most if not all the copies of the rabbit DNA fragment are integrated into one homologue of mouse chromosome 1. The possible use of this technique for the study of globin gene regulation is discussed.

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Specific expression of a foreign beta-globin gene in erythroid cells of transgenic mice.

The globin gene family represents an attractive system for the study of gene regulation during mammalian development, as its expression is subject to both tissue-specific and temporal regulation. While many aspects of globin gene structure and expression have been described extensively, relatively little is known about the cis-acting DNA sequences involved in the developmental regulation of globin gene expression. To begin to experimentally define these regulatory sequences, we have taken the approach of introducing cloned globin genes into the mouse germ line and examining their expression in the resulting transgenic animals. Here we describe a series of transgenic mice carrying a hybrid mouse/human adult beta-globin gene, several of which express the gene exclusively or predominantly in erythroid tissues. These studies demonstrate that regulatory sequences closely linked to the beta-globin gene are sufficient to specify a correct pattern of tissue-specific expression in a developing mouse, when the gene is integrated at a subset of foreign chromosomal positions.

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PubMedDate not supplied

Developmental regulation of a cloned adult beta-globin gene in transgenic mice.

At different stages of mammalian development, distinct embryonic, fetal and adult haemoglobins are synthesized in erythroid cells, a process termed haemoglobin switching. The cellular and molecular mechanisms controlling haemoglobin switching have been intensively studied, but remain poorly understood. To study the developmental regulation of globin gene expression, we have produced transgenic mice in which cloned globin genes are present in erythroid cells throughout development. Recently, we reported that adult mice in several transgenic lines carrying a hybrid mouse/human adult beta-globin gene, expressed the gene in a correct tissue-specific manner. This finding raised the question of whether an exogenous globin gene could also be subject to appropriate stage-specific regulation. We report here that the hybrid beta-globin gene, like the endogenous adult beta-globin genes, is inactive in yolk sac-derived embryonic erythroid cells and is expressed for the first time in fetal liver erythroid cells. Our results indicate that a stage-specific pattern of expression can be conferred by cis-acting regulatory elements closely linked to an adult beta-globin gene. They also suggest that the embryonic and adult beta-globin genes in the mouse are activated (or repressed) by distinct trans-acting regulatory factors present in embryonic, fetal and adult erythroid cells.

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PubMedDate not supplied

An embryonic pattern of expression of a human fetal globin gene in transgenic mice.

During the evolution of the beta-globin family gene in vertebrates, different globin genes acquired different developmental patterns of expression. In mammals, specific 'embryonic' beta-like globins are synthesized in the earliest erythroid cells, which differentiate in the yolk sac of the embryo. In most mammals the embryonic globin chains are replaced by 'adult' beta-globins in fetal and adult erythrocytes, which arise in the liver and bone marrow, respectively. However, in simian primates (including humans), a distinct 'fetal' type of beta-like globin chain predominates in fetal erythroid cells. Based on the pattern of DNA sequence homologies between different mammalian species, these fetal globin genes, G gamma and A gamma, are thought to have descended from an ancestral gene, 'proto-gamma', which was embryonic in its pattern of expression. In the mouse, as well as in most other mammalian species, the descendants of the proto-gamma gene continue to function as embryonic genes. To investigate the evolutionary changes that led to the 'fetal recruitment' of the gamma-globin genes in primates, we have introduced the cloned human G gamma-globin gene into the mouse germ line. We report here that the human G gamma gene reverts to an embryonic pattern of expression in the developing mouse. This observation suggests that during evolution a shift occurred in the timing of expression of a trans-acting signal controlling the proto-gamma gene.

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