Biomedical subjects

M Vigneron

Publications and source records attributed to M Vigneron.

At least 55 records · Page 3Linked to original sources

PubMed1989

The mouse Hox-1.4 gene: primary structure, evidence for promoter activity and expression during development.

This study reports the structure of the mouse homeobox-containing gene Hox-1.4 of the HOX-1 cluster, as well as its expression pattern during embryonic and fetal development. The overall structure of this gene includes two major exons, the second of which encodes the homeo-domain. The putative Hox-1.4 protein displays similarities with products of homologous genes located at the same relative positions in other HOX clusters. A fragment extending 360 base pairs (bp) upstream of a transcriptional start site was shown to be able to promote transcription in transfected cells. This fragment is GC-rich and contains binding sites for the Sp1 transcription factor. In situ hybridization studies revealed the Hox-1.4 expression pattern during development. As already reported for several other murine Hox genes, Hox-1.4 is expressed in the fetal central nervous system (CNS), in structures derived from somitic mesodermal condensations (sclerotomes, prevertebrae) as well as in several mesodermal components of various organs and structures such as lungs, gut, stomach, intestine and meso- and metanephros. This expression pattern is in good agreement with recent proposals concerning the involvement of such genes in the establishment of the vertebrate body plan as well as the relationship between the positions of these genes within their clusters and the anteroposterior restriction of their expression domains.

Amino Acid Sequence↗

PubMed1989

[Surgical treatment of complete atrioventricular canal. Value of the "composite double patch" technic].

Between January 1, 1982 and January 1, 1988, 49 complete corrections of complete atrioventricular canal were performed in children aged from 4 months to 8 years. 41 were infants less than 2 years' old and 31 were less than one year old. In the last 35 patients the "composite double patch" technique was used, consisting of closure of the interventricular septal defect with a dacron patch, followed by closure of the ostium primum with a pericardial patch. The mitral cleft was left intact in the last 6 operations. The overall mortality rate was 35 p. 100 (17 patients). It was 23 p. 100 in infants under 1 year and 17 p. 100 in infants aged from 6 to 12 months at the time of surgery (p less than 0.01). Seven of the 35 children in whom the "composite double patch" technique was used died (20 p. 100). Only one early death was recorded among the last 15 children operated upon. Two reoperations were performed: one within one month of the first operation, the other 4 months later for residual mitral regurgitation with haemolysis. 32 children were followed up for periods of 2 months to 6 years, 10 of them for more than 3 years. Two late deaths occurred during the follow-up. Grade 2 or 3/4 residual regurgitation was found in 14 patients who have regular clinical and echocardiographic examinations.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1989

[Plastic surgery of the anterior cruciate ligament: experimental study of intra-articular aramid fibers in dogs].

The authors explored the possibility of replacing an anterior cruciate ligament with an aramid fiber (Kevlar) implant. This study was performed in intra-articular site in 9 dogs and the average implantation period was 5 months. Studies were carried out by macroscopic, photon microscopy, and electron microscopy examination of the samples obtained at the time the animals were sacrificed. Clinical and radiographic studies of the knees were performed in order to assess functional consequences. Overall, the results showed a partial or complete rupture of 10 neoligaments out of the 17 studied ligaments; on the other hand, osseous anchorage and reintegration in the intra-articular zone appeared satisfactory. Kevlar fiber only partially meets the performance specifications for an artificial ligament intended to serve as an anterior cruciate ligament substitute. Some positive results have encouraged the authors to carry on further this experimental study.

Animals↗

PubMed1988

[Surgery of the thoracic aorta. Value of tissucol].

The techniques for sealing with the Tissucol fibrin glue, used in repair of aortic dissections and aneurysms, are described. We applied this method to 24 patients operated upon for acute (9 cases) or chronic (15 cases) lesions of the thoracic aorta. No patients died of haemorrhage, and post-operative bleeding was only 500 ml on average. Provided strict precautions are taken, this adjuvant haemostatic method considerably improves the immediate prognosis of acquired aortic lesions. Other operations of cardiac surgery may benefit from these sealing techniques the cost of which must be weighed against the blood transfusion units that are saved.

Aortic Dissection↗

PubMed1987

One cell-specific and three ubiquitous nuclear proteins bind in vitro to overlapping motifs in the domain B1 of the SV40 enhancer.

We have used the gel retardation assay to investigate the binding of nuclear proteins to the domain B1 of the SV40 enhancer, which contains the GT-II motif. Four proteins (GT-IIA, GT-IIB alpha, GT-IIB beta and GT-IIC) were detected, three of which were present in nuclear extracts from several cell lines. The fourth protein (GT-IIC) showed a clear cell-specificity, being absent from the lymphoid cell extracts tested. The results of methylation interference assays and of the binding of the proteins to mutated templates indicate that the domain B1 contains three distinct, but overlapping, protein-binding motifs (GT-IIA, B and C). The cell-specific binding of protein GT-IIC in vitro correlates with the in vivo enhancer activity of its cognate motif, strongly suggesting that this protein acts as a positive trans-acting enhancer factor. Two of the proteins also recognize other enhancer motifs; protein GT-IIB alpha binds to the microE3 motif present in the immunoglobulin heavy chain enhancer; protein GT-IIC binds to an enhancer motif of the polyomavirus mutant PyEC9.1 adapted to growth in F9 embryonal carcinoma cells, but not to the corresponding wild-type sequence.

Base Sequence↗

PubMed1987

In vitro binding of cell-specific and ubiquitous nuclear proteins to the octamer motif of the SV40 enhancer and related motifs present in other promoters and enhancers.

We have used the gel retardation and DNase I footprinting assays to investigate the in vitro binding of nuclear proteins to the octamer motif present in domain A of the SV40 enhancer and in other enhancer and promoter elements. Three apparently cell-specific (oct-B1A, oct-B1B and oct-B2) and one ubiquitous (oct-B3) proteins were detected in various lymphoid and non-lymphoid cell extracts. We show that the previously described 'ubiquitous' NF-A1 factor may correspond in fact to two proteins, oct-B1A in HeLa cells and oct-B1B in lymphoid cells. Interestingly, the HeLa cell protein oct-B1A formed a complex with the SV40 octamer, which could be detected in gel retardation, but not in DNase I footprinting assays. This absence of protection from DNase I digestion correlates with the inactivity of the SV40 octamer in HeLa cells in vivo. We have also found that the in vitro interaction between the SV40 octamer motif and the lymphoid cell-specific protein oct-B2 was negatively modulated by a component present in the nuclear extracts from several lymphoid cell lines. The interactions between the multiple octamer-binding proteins and the related octamer motifs present in other promoter and enhancer elements were systematically compared and the possible role of these proteins in the control of transcription is discussed.

Base Sequence↗

PubMed1987

In vitro binding of several cell-specific and ubiquitous nuclear proteins to the GT-I motif of the SV40 enhancer.

We have investigated the specific in vitro binding of nuclear proteins from several cell lines to the GT-I motif of the SV40 enhancer which overlaps with the canonical enhancer "core" homology. The binding of three proteins (GT-IA, GT-IB, and GT-IC), one of which (GT-IC) exhibits cell specificity, was detected. Competition and direct binding experiments demonstrated that the two ubiquitous proteins also bind to the GC-rich motif III from the 21-bp repeat upstream element of the SV40 early promoter and that protein GT-IA is most probably the transcription factor Sp1. The third, cell-specific protein GT-IC exhibited a high affinity for both the GT-I motif and an upstream element in the promoter of the mouse beta-major-globin gene, suggesting that this protein can act both as an enhancer and an upstream element trans-acting factor. The good correlation between the known cell-specific in vivo activity of the wild-type and mutated GT-I motif and the cell-specific binding of protein GT-IC in vitro strongly supports the conclusion that this protein is an enhancer factor. Interestingly, its cognate recognition sequence does not coincide with the core homology.

Animals↗

PubMed1987

Interferon-responsive regulatory elements in the promoter of the human 2',5'-oligo(A) synthetase gene.

The interferon (IFN)-activated human 2',5'-oligo(A) synthetase E gene contains 11 RNA starts and lacks TATA and CAAT signals. DNA sequences around the promoter make the expression of the chloramphenicol acetyltransferase gene (CAT) inducible over 20-fold by IFN. A 72-base-pair segment (E-IRS) immediately upstream of the RNA starts was defined as being required for IFN-activated expression of the E-gene promoter-CAT constructs and acts in a position-independent manner. It also confers IFN-activated enhancement to the herpes simplex virus thymidine kinase promoter. On this promoter, the 5' part of the E-IRS functions as a constitutive enhancer, while the last 16 base pairs of the E-IRS is sufficient to give IFN-induced expression. On the E-gene promoter, the constitutive enhancer and the IFN-activated sequence are both needed but can be separated. In addition, promoter competition experiments indicate a third regulatory region which helps to repress expression of the E gene in uninduced cells.

2',5'-Oligoadenylate Synthetase↗

PubMed1986

Efficient constitutive production of human IFN-gamma in Chinese hamster ovary cells.

A human genomic DNA segment of 5.6 kb containing the entire gene for immune interferon-gamma was fused through its 5'-untranslated region to the corresponding region of the simian virus 40 (SV40) T-antigen gene. The SV40 early promoter used contained a modified transcriptional enhancer element with a 93-bp repeat. Supercoiled plasmid DNA was used to transfect Chinese hamster ovary (CHO) cells, the selectable marker being a SV40-dihydrofolate gene construct. Constitutive expression of the IFN-gamma gene in primary transformants was high, especially if a Harvey murine sarcoma virus long terminal repeat (LTR) was present in addition to the SV40 promoter. After gene amplification by methotrexate selection, CHO-gamma cell lines were obtained that produce 1.5-2 million units of IFN-gamma per million cells and per day (200,000 molecules per cell per minute). Metabolic labeling showed that over 90% of the protein secreted by such cells is human IFN-gamma. A one-step immuno-affinity chromatography on monoclonal antibodies yielded pure IFN-gamma with 1-2 X 10(8) units/mg protein. Like IFN-gamma from human white blood cells, the IFN-gamma from CHO-gamma cells is a mixture of two glycoproteins of 26,000 and 20,000 daltons with traces of the unglycosylated 17,000-dalton polypeptide. Large-scale cultures in 1% serum routinely yield over 600,000 units of human IFN-gamma/ml culture per day.

Animals↗

PubMed1985

All six GC-motifs of the SV40 early upstream element contribute to promoter activity in vivo and in vitro.

Recombinants in which the six GC-motifs (I-VI) present in the upstream element of the SV40 early promoter region have been point mutated either individually or in pairs were used to determine the possible contribution of each GC-motif to the function of the overlapping early-early and late-early SV40 promoters. GC-motif I, and to a lesser extent, GC-motifs II and III, are critical for initiation at the early-early start sites. GC-motifs IV-VI play a subsidiary role. Mutations in GC-motifs I and II do not decrease the activity of the late-early promoter, whereas mutations in the GC-motifs III-VI have a moderate effect on it. The in vivo phenotype of the GC-motif mutants can be almost fully reproduced in vitro using a nuclear extract. DNase I protection footprinting experiments using wild-type or mutated templates and nuclear extracts indicate that each GC-motif behaves principally as an independent protein-binding site, presumably for transcription factor Sp1. The effect of changing the position of the 21-bp repeat region on initiation from the early-early and late-early start sites indicates that there is little flexibility in the position in which this upstream element can efficiently activate initiation of transcription from these start sites.

Base Sequence↗

PubMed1984

Mutational dissection of the 21 bp repeat region of the SV40 early promoter reveals that it contains overlapping elements of the early-early and late-early promoters.

Using quantitative S1 nuclease analysis and recombinants which contain the SV40 early promoter region linked to the rabbit beta-globin gene coding sequence, we have studied the effect of deletion, inversion and point mutations, located within the 21 bp repeat region, on initiation of transcription from the early-early and late-early startsites in the absence of T-antigen. Our data establish unequivocally that the six GC-rich repeats present in the 21 bp repeat region are essential elements of both the early-early and late-early promoters and that they are not redundant, since mutations, which affect only the GC-rich repeat most proximal to the TATA box, decrease drastically the activity of the early-early promoter, but increase that of the late-early promoter. On the other hand, the four GC-rich repeats most proximal to the 72 bp repeat are common elements of the two overlapping early-early and late-early promoters. Our results, which confirm that the early-early promoter is stronger than the late-early one, also support our previous suggestion that they are in competition for the transcriptional machinery. The general organization of the SV40 early promoter region is discussed.

Base Composition↗

PubMed1984

Effect of the 21-bp repeat upstream element on in vitro transcription from the early and late SV40 promoters.

The role of the 21-bp repeat region [simian virus 40 (SV40) coordinates 40-103] on early and late SV40 promoter functions has been investigated in vitro using a variety of mutated templates. Using either a HeLa whole cell extract or a S100 extract, we analyzed the transcripts by quantitative S1 nuclease mapping. GC-rich motifs contained in the 21-bp direct repeat constituted an essential element for efficient early transcription in vitro in agreement with previous in vivo results. These GC-rich motifs act in a non-polar fashion, since inversion of the 21-bp region did not reduce early transcription. Some point mutations in the 22-bp imperfectly repeated sequence, that drastically reduce initiations from the early promoter in vivo, had little effect in vitro, indicating that all the functions of these GC-rich motifs cannot be reproduced in vitro at present. The requirement for the 21-bp repeat region was less stringent when the concentration of the early promoter sequence was increased, which suggests that its function may be to facilitate the recognition of the 'weak' SV40 early TATA box. The multiple late start sites were accurately used in vitro and the GC-rich motifs contained in the 21-bp repeat region were an important element for efficient in vitro initiation of transcription from the late promoter, irrespective of their orientation. However, the effect of the 21-bp repeat region on late initiations decreased strikingly with increasing distance to the start sites, although it was still detectable over a distance of 220 bp. Under the present in vitro conditions, the 72-bp repeat region stimulates weakly both early and late transcription.

Chromosome Deletion↗

PubMed1982