F. Flamant - Academia.edu (original) (raw)
Papers by F. Flamant
The International journal of developmental biology, 1994
A new procedure, virofection, designed to stabilize the expression of transfected DNA has been de... more A new procedure, virofection, designed to stabilize the expression of transfected DNA has been developed. It exploits the capacity of retroviruses to integrate their genome into the chromosomes of host cells. The co-transfection of two plasmids, one carrying the genome of a defective retrovirus vector, the other one encoding all the retroviral proteins, results in a transient production of infectious virus particles. These particles can infect the neighboring cells and this leads to the stable integration of the vector genome. This procedure is time-saving and appears to be quite efficient. When applied to chicken embryonic fibroblasts cultured in vitro, it resulted in the stable expression of the lacZ gene in more than 30% of the cells, and did not induce chronic viremia. Stable lacZ expression was also achieved in chicken embryos in ovo. Virofection appears to be a promising and generally applicable method for implementing stable, safe and efficient gene transfer in vitro and in v...
Nucleic Acids Research, 1984
We studied the bleached mutant of Euglena gracilis Y BUD producing carotenoids and rich in chloro... more We studied the bleached mutant of Euglena gracilis Y BUD producing carotenoids and rich in chloroplast DNA. This mutant which was produced more than twenty years ago segregates permanently, forming 30 to 50% daughter cells without carotenoids and poor in chloroplast DNA. Electron microscopy and mapping with restriction enzymes show the deletion of a complete ribosomal operon out of the three present in the oriqinal strain.
Molecular Endocrinology, 1997
The thyroid hormone receptor-coding locus, c-erbAα, generates several mRNAs originating from a si... more The thyroid hormone receptor-coding locus, c-erbAα, generates several mRNAs originating from a single primary transcript that undergoes alternative splicing. We have identified for the first time two new transcripts, called TRΔα1 and TRΔα2[ mRNA for isoform α1 and α2 of the T3 receptor (TR), respectively], whose transcription is initiated from an internal promoter located within intron 7 of the c-erbAα gene. These two new transcripts exhibit tissue-specific patterns of expression in the mouse. These two patterns are in sharp contrast with the expression patterns of the full-length transcripts generated from the c-erbAα locus. TRΔα1 and TRΔα2 mRNAs encode N-terminally truncated isoforms of T3Rα1 and T3Rα2, respectively. The protein product of TRΔα1 antagonizes the transcriptional activation elicited by T3 and retinoic acid. This protein inhibits the ligand-induced activating functions of T3Rα1 and 9-cis-retinoic acid receptor-α but does not affect the retinoic acid-dependent activati...
Journal of Molecular Medicine, 1995
Journal of Molecular Endocrinology, 2004
We have generated transgenic reporter mice to analyze the spatio-temporal distribution of thyroid... more We have generated transgenic reporter mice to analyze the spatio-temporal distribution of thyroid hormone signaling during mouse brain development. The reporter system, utilizing a chimeric yeast Gal4 DNA-binding domain–thyroid hormone α ligand-binding domain fusion protein to drive lacZ expression, revealed that thyroid hormone signaling starts in the midbrain roof several days before the onset of thyroid gland function, and that it remains highly heterogeneous in the central nervous system throughout pre- and postnatal development. We speculate that this heterogeneity might provide neural cells with positional information during development.
Experimental Hematology, 1999
Constitutive expression of human colony-stimulating factor-1 receptor (CSF-1R) confers long-lasti... more Constitutive expression of human colony-stimulating factor-1 receptor (CSF-1R) confers long-lasting CSF-1-dependent proliferation to mouse myeloid cell lines. We developed mice transgenic for human CSF-1R because mouse CSF-1 cannot activate human CSF-1R. Then bone marrow cells from transgenic mice were plated onto MS-5 stromal cells expressing the membrane form of human CSF-1 (2M-1 cells) in order to combine the hematopoietic supporting properties of stromal cells and the proliferative effects of CSF-1. Thus, we were able to derive a hematopoietic cell line, called 47.10, that grew indefinitely under these conditions, whereas no cell line could be developed from nontransgenic mice. Proliferation of 47.10 cells is severely affected by neutralizing anti-CSF-1R monoclonal antibodies. Morphologic and cytofluorometry analysis established that most 47.10 cells are immature myelomonocytic cells. Consistent with this phenotype, the myeloid transcription factor PU.1, but not the erythroid transcription factor GATA-1, is expressed in 47.10 cells. A few 47.10 cells (3-5%) do not express lineage specific markers; they differentiate spontaneously to lineage-positive cells after replating on 2M-1 cells. In agar cultures, 47.10 cells form 7-and 14-day colonies in response to a cocktail of granulocyte/macrophage colony-stimulating factor (2.5 ng/mL), interleukin-3 (1 ng/mL), and mouse CSF-1 (10 ng/mL). Under these conditions, about 0.5% of 47.10 cells formed large 14-day colonies (Ͼ 1 mm) composed of mature monocytes and granulocytes, reflecting the presence of progenitors endowed with high proliferative potential (HPP-47.10 cells). In conclusion, we have characterized a novel continuous myeloid cell line presenting a hierarchical structure similar to that of the bone marrow progenitor cell compartment.
Current Genetics, 1984
The chloroplast DNA of a wild type photosynthetic variant of Euglena gracilis (ATCC n ° 10616) wi... more The chloroplast DNA of a wild type photosynthetic variant of Euglena gracilis (ATCC n ° 10616) with five ribosomal cistrons has been analyzed by restriction mapping. The results complete the electron microscope study of Koller and Delius (MGG 188,305, 1982); they support a model of formation of the variant DNA by rearrangement of the wild type ribosomal cistrons through unequal crossing-over. The recombination sites have been determined. The recombination model proposed also explains the formation of the "Z-S" variant with a single ribosomal cistron (Wurtz and Buetow 1981).
Journal of Neuroscience, 2009
Thyroid hormone receptor  (TR) dysfunction leads to deafness in humans and mice. Deafness in TR... more Thyroid hormone receptor  (TR) dysfunction leads to deafness in humans and mice. Deafness in TR Ϫ/Ϫ mutant mice has been attributed to TR-mediated control of voltage-and Ca 2ϩ-activated K ϩ (BK) channel expression in inner hair cells (IHCs). However, normal hearing in young constitutive BK␣ Ϫ/Ϫ mutants contradicts this hypothesis. Here, we show that mice with hair cell-specific deletion of TR after postnatal day 11 (P11) have a delay in BK␣ expression but normal hearing, indicating that the origin of hearing loss in TR Ϫ/Ϫ mutant mice manifested before P11. Analyzing the phenotype of IHCs in constitutive TR Ϫ/Ϫ mice, we found normal Ca 2ϩ current amplitudes, exocytosis, and shape of compound action potential waveforms. In contrast, reduced distortion product otoacoustic emissions and cochlear microphonics associated with an abnormal structure of the tectorial membrane and enhanced tectorin levels suggest that disturbed mechanical performance is the primary cause of deafness resulting from TR deficiency.
Molecular and cellular biology, 1987
On-line optimization of fermentation processes can be greatly aided by the availability of inform... more On-line optimization of fermentation processes can be greatly aided by the availability of information on the physiological state of the cell. The goal of our "BioLux" research project was to design a recombinant cell capable of intracellular monitoring of product synthesis and to use it as part of an automated fermentation system. A recombinant plasmid was constructed containing an inducible promoter that controls the gene coding for a model protein and the genes necessary for bioluminescence. The cells were cultured in microfermenters equipped with an on-line turbidity sensor and a specially designed on-line light sensor capable of continuous measurement of bioluminescence. Initial studies were done under simple culture conditions, and a linear correlation between luminescence and protein production was obtained. Such specially designed recombinant bioluminescent cells can potentially be applied for model-based inference of intracellular product formation, as well as for optimization and control of recombinant fermentation processes.
Germ Cell Tumours III, 1994
Pharmacological Reviews, 2006
... Flores-Morales A, Gullberg H, Fernandez L, Stahlberg ... Mol Endocrinol 6: 429-442. Abstract/... more ... Flores-Morales A, Gullberg H, Fernandez L, Stahlberg ... Mol Endocrinol 6: 429-442. Abstract/FREE Full Text. ↵ Forrest D, Erway LC, Ng L, Altschuler R, and Curran T (1996a) Thyroid hormone receptor beta is essential for development of auditory function. Nat Genet 13: 354-357. ...
Molecular Endocrinology, 2002
Mice devoid of all TRs are viable, whereas Pax8 Ϫ/Ϫ mice, which lack the follicular cells produci... more Mice devoid of all TRs are viable, whereas Pax8 Ϫ/Ϫ mice, which lack the follicular cells producing T 4 and T 3 in the thyroid gland, die during the first weeks of postnatal life. A precise comparison between the two types of mutants reveals that their phenotypes are similar, but the defects in spleen, bone, and small intestine are more pronounced in Pax8 Ϫ/Ϫ mice. This is interpreted as the result of a negative effect of the unliganded TR on thyroid hormone target genes expression in the Pax8 Ϫ/Ϫ mutants. Pax8/TR␣ compound mutants can survive to adulthood, and the expression of target genes is partially restored. This demonstrates the importance of TR␣ aporeceptor activity in several aspects of postnatal development. (Molecular
Journal of Molecular Endocrinology, 2004
We have generated transgenic reporter mice to analyze the spatio-temporal distribution of thyroid... more We have generated transgenic reporter mice to analyze the spatio-temporal distribution of thyroid hormone signaling during mouse brain development. The reporter system, utilizing a chimeric yeast Gal4 DNA-binding domain-thyroid hormone ligand-binding domain fusion protein to drive lacZ expression, revealed that thyroid hormone signaling starts in the midbrain roof several days before the onset of thyroid gland function, and that it remains highly heterogeneous in the central nervous system throughout pre-and postnatal development. We speculate that this heterogeneity might provide neural cells with positional information during development.
Developmental Biology, 2003
Thyroid hormone is a major regulator of postnatal brain development, but the precise molecular me... more Thyroid hormone is a major regulator of postnatal brain development, but the precise molecular mechanisms underlying its action in this organ remain poorly understood. We used microarray analysis to identify new target genes in brain. Thyroid hormone treatment of hypothyroid Pax8 Ϫ/Ϫ knockout mice, which lack thyroid follicular cells, had a very limited global effect on brain transcripts. This analysis mainly identified cyclin D2 as a new thyroid hormone target gene in the cerebellum of hypothyroid mice. Thyroid hormone receptor (TR␣ and/or TR) knockout mice studies provided further genetic evidence that cyclin D2 is likely to mediate the antiapoptotic effect exerted by thyroid hormone on the cerebellum external granular layer neuroblasts but that this transcriptional activation is not directly exerted by the thyroid hormone receptors.
The International journal of developmental biology, 1994
A new procedure, virofection, designed to stabilize the expression of transfected DNA has been de... more A new procedure, virofection, designed to stabilize the expression of transfected DNA has been developed. It exploits the capacity of retroviruses to integrate their genome into the chromosomes of host cells. The co-transfection of two plasmids, one carrying the genome of a defective retrovirus vector, the other one encoding all the retroviral proteins, results in a transient production of infectious virus particles. These particles can infect the neighboring cells and this leads to the stable integration of the vector genome. This procedure is time-saving and appears to be quite efficient. When applied to chicken embryonic fibroblasts cultured in vitro, it resulted in the stable expression of the lacZ gene in more than 30% of the cells, and did not induce chronic viremia. Stable lacZ expression was also achieved in chicken embryos in ovo. Virofection appears to be a promising and generally applicable method for implementing stable, safe and efficient gene transfer in vitro and in v...
Nucleic Acids Research, 1984
We studied the bleached mutant of Euglena gracilis Y BUD producing carotenoids and rich in chloro... more We studied the bleached mutant of Euglena gracilis Y BUD producing carotenoids and rich in chloroplast DNA. This mutant which was produced more than twenty years ago segregates permanently, forming 30 to 50% daughter cells without carotenoids and poor in chloroplast DNA. Electron microscopy and mapping with restriction enzymes show the deletion of a complete ribosomal operon out of the three present in the oriqinal strain.
Molecular Endocrinology, 1997
The thyroid hormone receptor-coding locus, c-erbAα, generates several mRNAs originating from a si... more The thyroid hormone receptor-coding locus, c-erbAα, generates several mRNAs originating from a single primary transcript that undergoes alternative splicing. We have identified for the first time two new transcripts, called TRΔα1 and TRΔα2[ mRNA for isoform α1 and α2 of the T3 receptor (TR), respectively], whose transcription is initiated from an internal promoter located within intron 7 of the c-erbAα gene. These two new transcripts exhibit tissue-specific patterns of expression in the mouse. These two patterns are in sharp contrast with the expression patterns of the full-length transcripts generated from the c-erbAα locus. TRΔα1 and TRΔα2 mRNAs encode N-terminally truncated isoforms of T3Rα1 and T3Rα2, respectively. The protein product of TRΔα1 antagonizes the transcriptional activation elicited by T3 and retinoic acid. This protein inhibits the ligand-induced activating functions of T3Rα1 and 9-cis-retinoic acid receptor-α but does not affect the retinoic acid-dependent activati...
Journal of Molecular Medicine, 1995
Journal of Molecular Endocrinology, 2004
We have generated transgenic reporter mice to analyze the spatio-temporal distribution of thyroid... more We have generated transgenic reporter mice to analyze the spatio-temporal distribution of thyroid hormone signaling during mouse brain development. The reporter system, utilizing a chimeric yeast Gal4 DNA-binding domain–thyroid hormone α ligand-binding domain fusion protein to drive lacZ expression, revealed that thyroid hormone signaling starts in the midbrain roof several days before the onset of thyroid gland function, and that it remains highly heterogeneous in the central nervous system throughout pre- and postnatal development. We speculate that this heterogeneity might provide neural cells with positional information during development.
Experimental Hematology, 1999
Constitutive expression of human colony-stimulating factor-1 receptor (CSF-1R) confers long-lasti... more Constitutive expression of human colony-stimulating factor-1 receptor (CSF-1R) confers long-lasting CSF-1-dependent proliferation to mouse myeloid cell lines. We developed mice transgenic for human CSF-1R because mouse CSF-1 cannot activate human CSF-1R. Then bone marrow cells from transgenic mice were plated onto MS-5 stromal cells expressing the membrane form of human CSF-1 (2M-1 cells) in order to combine the hematopoietic supporting properties of stromal cells and the proliferative effects of CSF-1. Thus, we were able to derive a hematopoietic cell line, called 47.10, that grew indefinitely under these conditions, whereas no cell line could be developed from nontransgenic mice. Proliferation of 47.10 cells is severely affected by neutralizing anti-CSF-1R monoclonal antibodies. Morphologic and cytofluorometry analysis established that most 47.10 cells are immature myelomonocytic cells. Consistent with this phenotype, the myeloid transcription factor PU.1, but not the erythroid transcription factor GATA-1, is expressed in 47.10 cells. A few 47.10 cells (3-5%) do not express lineage specific markers; they differentiate spontaneously to lineage-positive cells after replating on 2M-1 cells. In agar cultures, 47.10 cells form 7-and 14-day colonies in response to a cocktail of granulocyte/macrophage colony-stimulating factor (2.5 ng/mL), interleukin-3 (1 ng/mL), and mouse CSF-1 (10 ng/mL). Under these conditions, about 0.5% of 47.10 cells formed large 14-day colonies (Ͼ 1 mm) composed of mature monocytes and granulocytes, reflecting the presence of progenitors endowed with high proliferative potential (HPP-47.10 cells). In conclusion, we have characterized a novel continuous myeloid cell line presenting a hierarchical structure similar to that of the bone marrow progenitor cell compartment.
Current Genetics, 1984
The chloroplast DNA of a wild type photosynthetic variant of Euglena gracilis (ATCC n ° 10616) wi... more The chloroplast DNA of a wild type photosynthetic variant of Euglena gracilis (ATCC n ° 10616) with five ribosomal cistrons has been analyzed by restriction mapping. The results complete the electron microscope study of Koller and Delius (MGG 188,305, 1982); they support a model of formation of the variant DNA by rearrangement of the wild type ribosomal cistrons through unequal crossing-over. The recombination sites have been determined. The recombination model proposed also explains the formation of the "Z-S" variant with a single ribosomal cistron (Wurtz and Buetow 1981).
Journal of Neuroscience, 2009
Thyroid hormone receptor  (TR) dysfunction leads to deafness in humans and mice. Deafness in TR... more Thyroid hormone receptor  (TR) dysfunction leads to deafness in humans and mice. Deafness in TR Ϫ/Ϫ mutant mice has been attributed to TR-mediated control of voltage-and Ca 2ϩ-activated K ϩ (BK) channel expression in inner hair cells (IHCs). However, normal hearing in young constitutive BK␣ Ϫ/Ϫ mutants contradicts this hypothesis. Here, we show that mice with hair cell-specific deletion of TR after postnatal day 11 (P11) have a delay in BK␣ expression but normal hearing, indicating that the origin of hearing loss in TR Ϫ/Ϫ mutant mice manifested before P11. Analyzing the phenotype of IHCs in constitutive TR Ϫ/Ϫ mice, we found normal Ca 2ϩ current amplitudes, exocytosis, and shape of compound action potential waveforms. In contrast, reduced distortion product otoacoustic emissions and cochlear microphonics associated with an abnormal structure of the tectorial membrane and enhanced tectorin levels suggest that disturbed mechanical performance is the primary cause of deafness resulting from TR deficiency.
Molecular and cellular biology, 1987
On-line optimization of fermentation processes can be greatly aided by the availability of inform... more On-line optimization of fermentation processes can be greatly aided by the availability of information on the physiological state of the cell. The goal of our "BioLux" research project was to design a recombinant cell capable of intracellular monitoring of product synthesis and to use it as part of an automated fermentation system. A recombinant plasmid was constructed containing an inducible promoter that controls the gene coding for a model protein and the genes necessary for bioluminescence. The cells were cultured in microfermenters equipped with an on-line turbidity sensor and a specially designed on-line light sensor capable of continuous measurement of bioluminescence. Initial studies were done under simple culture conditions, and a linear correlation between luminescence and protein production was obtained. Such specially designed recombinant bioluminescent cells can potentially be applied for model-based inference of intracellular product formation, as well as for optimization and control of recombinant fermentation processes.
Germ Cell Tumours III, 1994
Pharmacological Reviews, 2006
... Flores-Morales A, Gullberg H, Fernandez L, Stahlberg ... Mol Endocrinol 6: 429-442. Abstract/... more ... Flores-Morales A, Gullberg H, Fernandez L, Stahlberg ... Mol Endocrinol 6: 429-442. Abstract/FREE Full Text. ↵ Forrest D, Erway LC, Ng L, Altschuler R, and Curran T (1996a) Thyroid hormone receptor beta is essential for development of auditory function. Nat Genet 13: 354-357. ...
Molecular Endocrinology, 2002
Mice devoid of all TRs are viable, whereas Pax8 Ϫ/Ϫ mice, which lack the follicular cells produci... more Mice devoid of all TRs are viable, whereas Pax8 Ϫ/Ϫ mice, which lack the follicular cells producing T 4 and T 3 in the thyroid gland, die during the first weeks of postnatal life. A precise comparison between the two types of mutants reveals that their phenotypes are similar, but the defects in spleen, bone, and small intestine are more pronounced in Pax8 Ϫ/Ϫ mice. This is interpreted as the result of a negative effect of the unliganded TR on thyroid hormone target genes expression in the Pax8 Ϫ/Ϫ mutants. Pax8/TR␣ compound mutants can survive to adulthood, and the expression of target genes is partially restored. This demonstrates the importance of TR␣ aporeceptor activity in several aspects of postnatal development. (Molecular
Journal of Molecular Endocrinology, 2004
We have generated transgenic reporter mice to analyze the spatio-temporal distribution of thyroid... more We have generated transgenic reporter mice to analyze the spatio-temporal distribution of thyroid hormone signaling during mouse brain development. The reporter system, utilizing a chimeric yeast Gal4 DNA-binding domain-thyroid hormone ligand-binding domain fusion protein to drive lacZ expression, revealed that thyroid hormone signaling starts in the midbrain roof several days before the onset of thyroid gland function, and that it remains highly heterogeneous in the central nervous system throughout pre-and postnatal development. We speculate that this heterogeneity might provide neural cells with positional information during development.
Developmental Biology, 2003
Thyroid hormone is a major regulator of postnatal brain development, but the precise molecular me... more Thyroid hormone is a major regulator of postnatal brain development, but the precise molecular mechanisms underlying its action in this organ remain poorly understood. We used microarray analysis to identify new target genes in brain. Thyroid hormone treatment of hypothyroid Pax8 Ϫ/Ϫ knockout mice, which lack thyroid follicular cells, had a very limited global effect on brain transcripts. This analysis mainly identified cyclin D2 as a new thyroid hormone target gene in the cerebellum of hypothyroid mice. Thyroid hormone receptor (TR␣ and/or TR) knockout mice studies provided further genetic evidence that cyclin D2 is likely to mediate the antiapoptotic effect exerted by thyroid hormone on the cerebellum external granular layer neuroblasts but that this transcriptional activation is not directly exerted by the thyroid hormone receptors.