Biomedical subjects

A Vignal

Publications and source records attributed to A Vignal.

At least 55 records · Page 3Linked to original sources

PubMed1994

Assignment of 112 microsatellite markers to 23 chromosome 11 subregions delineated by somatic hybrids: comparison with the genetic map.

Using a panel of 25 somatic cell hybrids, we have regionally localized 112 microsatellite markers generated by Généthon and assigned to chromosome 11. A genetic map of 74 of them was produced using linkage analysis of the eight largest CEPH (Centre d'Etude du Polymorphisme Humain) families. They could be ordered on chromosome 11 with an average distance of 2.1 cM. The tight correlation observed between the genetic order and the physical assignment of these microsatellites reinforces the genetic map data. These newly localized markers identified by the PCR method using a standardized protocol represent useful tools for mapping YAC clones and establishing YAC contigs and for studying genetic diseases or cancers associated with specific genes and/or germinal/somatic rearrangements of chromosome 11.

Animals↗

PubMed1994

The 1993-94 Généthon human genetic linkage map.

In 1992, we described a second-generation genetic linkage map of the human genome. Using 1,267 new microsatellite markers, we now present a new genetic linkage map containing a total of 2,066 (AC)n short tandem repeats, 60% of which show a heterozygosity of over 0.7. Statistical linkage analysis based on the genotyping of eight large CEPH families placed these markers in the 23 linkage groups. The map includes 1,266 intervals and spans a total distance of 3690 centiMorgans (cM). A total of 1,041 markers could be ordered with odds ratios greater than 1000:1. About 56% of this map is at a distance of 1 cM or less from one of its markers.

Animals↗

PubMed1994

A radiation hybrid map of 506 STS markers spanning human chromosome 11.

We present a high resolution radiation hybrid map of human chromosome 11 using 506 sequence tagged sites (STSs) scored on a panel of 86 radiation hybrids. The 506 STSs fall into 299 unique positions (average resolution of about 480 kilobases (kb)) that span the whole chromosome. A subset of 260 STSs (143 positions) form a framework map that has a resolution of approximately 1 megabase between adjacent positions and is ordered with odds of at least 1,000:1. The centromere was clearly defined with pericentric markers unambiguously assigned to the short or long arm. The map contains most genes (125) and expressed sequence tags (26) currently assigned to chromosome 11 and more than half of the STSs are polymorphic microsatellite loci. These markers and the map can be used for high resolution physical and genetic mapping.

Animals↗

PubMed1994

A third locus for autosomal dominant cerebellar ataxia type I maps to chromosome 14q24.3-qter: evidence for the existence of a fourth locus.

The autosomal dominant cerebellar ataxias (ADCA) type I are a group of neurological disorders that are clinically and genetically heterogeneous. Two genes implicated in the disease, SCA1 (spinal cerebellar ataxia 1) and SCA2, are already localized. We have mapped a third locus to chromosome 14q24.3-qter, by linkage analysis in a non-SCA1/non-SCA2 family and have confirmed its existence in a second such family. We suggest designating this new locus "SCA3". Combined analysis of the two families restricted the SCA3 locus to a 15-cM interval between markers D14S67 and D14S81. The gene for Machado-Joseph disease (MJD), a clinically different form of ADCA type I, has been recently assigned to chromosome 14q24.3-q32. Although the SCA3 locus is within the MJD region, linkage analyses cannot yet demonstrate whether they result from mutations of the same gene. Linkage to all three loci (SCA1, SCA2, and SCA3) was excluded in another family, which indicates the existence of a fourth ADCA type I locus.

Adult↗

PubMed1993

Localization of Friedreich ataxia phenotype with selective vitamin E deficiency to chromosome 8q by homozygosity mapping.

Friedreich ataxia and ataxia with selective vitamin E deficiency (AVED) share very similar clinical phenotypes. We have mapped the AVED locus to proximal 8q with only three large consanguinous Tunisian families, representing to our knowledge the first use of homozygosity mapping for primary linkage analysis. Subsequently, three additional families showed linkage with the same markers. A maximum lod score of 17.9 was obtained at theta = 0 for the haplotype D8S260-D8S510, consisting of the two closest markers. With only 6 families, the AVED locus is therefore mapped precisely as illustrated by the lod-1 confidence interval of 2.4 cM on either side of D8S260-D8S510. Isolation of a yeast artificial chromosome contig > 800 kilobases (kb) showed that D8S260 and D8S510 are less than 400 kb apart.

Adult↗

PubMed1993

Relationship between Charcot-Marie-Tooth 1A and Smith-Magenis regions. snU3 may be a candidate gene for the Smith-Magenis syndrome.

The juxtacentromeric region of the human chromosome 17 short arm (17p11.2-p12) contains genes involved in the Charcot-Marie-Tooth type 1A disease (CMT1A) and the Smith-Magenis syndrome (SMS). CMT1A is associated with a duplication of a short segment whereas SMS is linked to microdeletions, extending toward the centromere. We describe the construction and analysis of a 5 Mb YAC contig spanning the CMT1A duplicated segment and the distal part of four SMS microdeletions. We concluded that the YAC contig contains about 1Mb of genomic DNA which is deleted in the four SMS patients analysed. Moreover two YACs contain both STS deleted in SMS (U3) and STS duplicated in CMT1A (5H5), but the proximal breakpoint associated with the CMT1A duplication is not the same as the distal SMS breakpoint we studied. Finally we located five new STS in SMS deletion. Two of them, a microsatellite (D17S805(23)) and the gene coding for small nuclear RNA U3, have been localized in the contig we described. We may also note that snU3 is the first expressed sequence localized in an SMS deletion so far. The possible participation of this gene in the SMS phenotype is discussed.

Base Sequence↗

PubMed1993

Severe childhood autosomal recessive muscular dystrophy with the deficiency of the 50 kDa dystrophin-associated glycoprotein maps to chromosome 13q12.

We have recently demonstrated the specific deficiency for the 50 kDa dystrophin-associated glycoprotein (50DAG) in Algerian patients afflicted with severe childhood autosomal recessive muscular dystrophy with DMD-like phenotype (SCARMD). A similar disease affecting Tunisian patients was linked to chromosome 13q but the status of the 50DAG was not investigated. Here we show by linkage analysis of Algerian families that the genetic defect which leads, either directly or indirectly, to the deficiency of the 50DAG in skeletal muscle is localized to the proximal part of chromosome 13q. We have not found any evidence of genetic heterogeneity among the thirteen families studied. It remains to be demonstrated whether the 50DAG gene maps at 13q12, and to determine if it is mutated in this disease.

Child↗

PubMed1992

A second-generation linkage map of the human genome.

A linkage map of the human genome has been constructed based on the segregation analysis of 814 newly characterized polymorphic loci containing short tracts of (C-A)n repeats in a panel of DNAs from eight large families. Statistical linkage analysis placed 813 of the markers into 23 linkage groups corresponding to the 22 autosomes and the X chromosome; 605 show a heterozygosity above 0.7 and 553 could be ordered with odds ratios above 1,000:1. The distance spanned corresponds to approximately 90% of the estimated length of the human genome.

Chromosome Mapping↗

PubMed1991

Erythrocyte glycophorin B deficiency may occur by two distinct gene alterations.

The genomic DNA from rare persons whose erythrocytes are deficient in glycophorin B (GPB) (S-s-U- phenotype), was examined by Southern hybridizations using glycophorin B probes and was subdivided into two main categories. In the type I variant (Fav., M.H., S.K.), we found that the S-s-U- condition is generated by a large gene deletion extending from exons B2 to B4 of glycophorin B gene. Conversely, in the type II variant (Del.), the entire gene is present, and its promoter is almost similar to common Glycophorin A (GPA) and GPB as well as to type I promoters, except for four-point mutations, which do not occur in potential cis-acting elements. We concluded that the same phenotypic glycophorin B deficiency may occur by different gene alterations, including either a gene deletion or a mutation that might alter transcription or translation of the gene.

Blotting, Southern↗

PubMed1990

Promoter sequence and chromosomal organization of the genes encoding glycophorins A, B and E.

The promoter and exon 1 sequences of the genes encoding erythrocyte glycophorins GPA, GPB and GPE were investigated in detail, both from a genomic clone sorted out of a human leukocyte library and from genomic clones obtained by polymerase chain reaction amplification of total genomic DNA from control individuals and from GAP and/or GPB deletion variants. The three exons 1 and upstream sequences were shown to be highly homologous with only a few point mutations that did not affect the potential cis-acting elements (CACCC, NF-E1 and NF-E2) that are present in the same position within the three genes. Moreover, these genes share the same transcription start point. Analysis of the exon 1 and promoter sequences together with the gene defects occurring in the GP variants indicate that unequal cross-overs between the three genes are responsible for deletions and the generation of hybrid gene structures in which the promoter of one gene is brought close to another gene of the family. On the basis of these studies, a model of the gene organization is proposed to explain the rearrangements occurring in the variants.

Base Sequence↗

PubMed1990

A novel gene member of the human glycophorin A and B gene family. Molecular cloning and expression.

A new gene closely related to the glycophorin A (GPA) and glycophorin B (GPB) genes has been identified in the normal human genome as well as in that of persons with known alterations of GPA and/or GPB expression. This gene, called glycophorin E (GPE), is transcribed into a 0.6-kb message which encodes a 78-amino-acid protein with a putative leader peptide of 19 residues. The first 26 amino acids of the mature protein are identical to those of M-type glycophorin A (GPA), but the C-terminal domain (residues 27-59) differs significantly from those of glycophorins A and B (GPA and GPB). The GPE gene consists of four exons distributed over 30 kb of DNA, and its nucleotide sequence is homologous to those of the GPA and GPB genes in the 5' region, up to exon 3. Because of branch and splice site mutations, the GPE gene contains a large intron sequence partially used as exons in GPA and GPB genes. Compared to its counterpart in the GPB gene, exon 3 of the GPE gene contains several point mutations, an insertion of 24 bp, and a stop codon which shortens the reading frame. Downstream from exon 3, the GPE and the GPB sequences are virtually identical and include the same Alu repeats. Thus, it is likely that the GPE and GPB genes have evolved by a similar mechanism. From the analysis of the GPA, GPB and GPE genes in glycophorin variants [En(a-), S-s-U- and Mk], it is proposed that the three genes are organized in tandem on chromosome 4. Deletion events within this region may remove one or two structural gene(s) and may generate new hybrid structures in which the promoter region of one gene is positioned upstream from the body of another gene of the same family. This model of gene organization provides a basis with which to explain the diversity of the glycophorin gene family.

Amino Acid Sequence↗

PubMed1989

Structure of the 5' flanking region of the gene encoding human glycophorin A and analysis of its multiple transcripts.

Glycophorin A (GPA), the major sialoglycoprotein of human erythrocytes, is the carrier for blood group MN antigens and a receptor for viruses, bacteria and parasites. (1) Three distinct GPA mRNAs (1.0, 1.7 and 2.2 kb) have been previously identified in erythroid tissues by Northern-blot analysis. It is shown here by sequence analysis of several human fetal liver cDNAs, and by transcription start point (tsp) determination using primer extension analysis, that the production of the multiple GPA mRNAs is governed by poly(A) site choice generating 3'-untranslated regions of different length, and not by the tsp heterogeneity, since all messages exhibit the same cap site (tsp). (2) The structural gene encoding GPA has been recently cloned [Vignal et al., Eur. J. Biochem. 184 (1989) 337-344; Kudo and Fukuda, Proc. Natl. Acad. Sci. USA 86 (1989) 4619-4623] and we have now determined the sequence of a DNA genomic fragment upstream from the tsp. This fragment does not contain the typical TATA and CAAT boxes found in a number of tissue-specific genes, but contains typical motifs like the CACC, nuclear factor erythroid 1 and 2 elements, which have been identified recently in several erythroid-specific promoters, therefore suggesting that transcription of these genes might be regulated by the same or analogous factors.

Amino Acid Sequence↗

PubMed1989

Molecular analysis of glycophorin A and B gene structure and expression in homozygous Miltenberger class V (Mi. V) human erythrocytes.

In the Miltenberger class V (Mi. V) condition, red cells lack glycophorin A (GPA) and glycophorin B (GPB) but carry instead an unusual glycoprotein thought to be a hybrid molecule produced by the unequal crossing-over between the closely linked genes encoding for GPA and GPB. By Western blot analysis with rabbit anti-GPA antibodies specific for discrete domains of GPA, it was found that the Mi. V glycoprotein (donor F. M.) contains approximately 60 amino acid residues of GPA at its N-terminus. As a preliminary approach to the molecular analysis of this variant the restriction maps of the GPA and GPB genes were established by Southern blot analysis of genomic DNA and from genomic clones isolated from a human leukocyte library constructed in lambda EMBL4. The GPA and GPB genes cover about 30 kb of DNA and are organized into seven exons (A-1-A-7) and five exons (B-1-B-5), respectively. In addition to the normal genes, a third gene (named inv), closely resembling the GPA and GPB genes, was also identified. In the homozygous Mi. V individual the normal GPA and GPB genes were absent, but an unusual form of gene structure was detected by Southern blot analysis. The Mi. V glycoprotein gene was composed of exon B-1 of the GPB gene followed by exons A-2 and A-3 of the GPA gene and the exons B-3, B-4 and B-5 of the GPB gene. Exon B-1 can be distinguished from exon A-1 of GPA since it is located within a different restriction fragment, but both encode the same amino acid sequence (N-terminal region of the signal peptides). Using the polymerase chain reaction, the junction between exon A-3 and exon B-3 was confirmed by amplification of the DNA region where the putative crossing-over has occurred and it was deduced that the Mi. V glycoprotein is a hybrid molecule composed of amino acid residues 1-58 from GPA fused to amino acid residues 27-72 of GPB. In addition, the finding that part of the signal peptide and the 5'-untranslated region are derived from GPB suggests that the genetic background of the Mi. V variant is rather complex and may involve a cascade of recombination or gene conversion events.

Amino Acid Sequence↗

PubMed1988

Alteration of the genes for glycophorin A and B in glycophorin-A-deficient individuals.

Glycophorins A and B are homologous glycoproteins of the red cell membrane which carry the blood-group MN and Ss antigens, respectively, and are encoded by two distinct genes closely linked on chromosome 4, which are probably derived from each other by duplication during evolution. The lack of glycophorin A is associated with the rare phenotype En(a-), indicating individuals who are defective for MN antigens, as well as for the Ena antigens, also located on this glycoprotein. The En(a-) condition is heterogenous and includes two categories of variants exemplified by the Finnish and the English types referred to as En(Fin) and En(UK), respectively. By Southern blot and preliminary genomic clone analyzes we have compared the status of the genes for glycophorins A and B, as well as that of the gene encoding glycophorin C, another unrelated red cell membrane glycoprotein, in the En(a-) variants and in the En(a+) control donors. Our data indicate that the En(Fin) variant is homozygous for a complete deletion of the glycophorin A gene without any detectable abnormality of the genes encoding glycophorins B or C. In the genome of the En(UK) variant, with the presumed genotype Mk/En(UK), and where the Mk condition abolishes the expression of MN and Ss antigens, we have identified several abnormalities of the glycophorin A and B genes, but the glycophorin C gene was unaffected. Our results strongly support the view that in Mk chromosome the glycophorin A and B genes are largely deleted, whereas the En(UK) chromosome probably contains a gene fusion product encoding a hybrid glycoprotein AM-B, composed of the N-terminal portion of a blood group M-type glycophorin A and of the C-terminal portion of glycophorin B. The determination of the 5' and 3' limits of the hybrid gene and elucidation of the mechanism involved will require sequencing of the rearranged DNA of the variant and a full knowledge of the organization of the glycophorin A and B genes.

Blotting, Southern↗

PubMed1987

The structure of tissue on cell culture-extracted thyroglobulin is independent of its iodine content.

The major protein synthesized in vitro by the ovine thyroid cell line OVNIS 6H is the prothyroid hormone thyroglobulin. Purified from serum-free cell culture media using sucrose gradient centrifugation, the thyroglobulin dimer was analysed for iodine content and observed by electron microscopy. In their usual medium, the OVNIS 6H cells produce a very poorly iodinated thyroglobulin containing 0.05 I atom per molecule. When cultured with methimazole or propylthiouracil, two inhibitors of iodide organification, less than 0.007 I atom/molecules was found. These molecules purified from cell cultures were compared to those purified from ovine thyroid tissue containing 26 I atoms/mol. Despite large differences in iodine content, the three preparations all consist of 19 S thyroglobulin dimers with the classical ovoidal shape. The variability in size measurements remains in a 2% range for all thyroglobulin types. Consequently, no real significant variation can be found between the highly iodinated thyroglobulin isolated from tissue, and the poorly or non-iodinated thyroglobulins isolated from cells cultured with or without methimazole or propylthiouracil.

Animals↗

PubMed1983

Production and in vitro utilization of monoclonal antibodies to human thyroglobulin.

Human thyroglobulin (Tg) was used as an antigen in the development of antibodies by the hybridoma technique. From four antibodies that bound more than 40% labeled Tg, two were characterized (182/E4 and 211/A5). They were both of the immunoglobulin G 2ab subclass, and provided an affinity constants (Ka) of 1.2 X 10(10) and 7.7 X 10(9) mol-1, respectively. The specificity of these antibodies was demonstrated by the absence of cross-reaction by monoiodothyronine, diiodothyronine, T3, T4, and sialic acid. A RIA was developed with 182/E4 or 211/A5, and the least detectable dose, based on the standard curve, was 10 ng/ml. The immunoreactivities of 182/E4 and 211/A5 to four Tg preparations different in iodine content appeared to be identical. Histochemical staining was used on normal and neoplastic tissues with both antibodies. Positive reactions were obtained in both cells and colloid, with heterogeneous staining from one follicle to another. Papillary carcinoma showed numerous positive cells, in contrast with Hürtle cell tumors which displayed very few positive cells. Anaplasic giant and spindle cells were negative. Monoclonal antibodies to human Tg are useful for in vitro detection of Tg.

Animals↗

PubMed1982

Thyrotrophin stimulation of adenylate cyclase and iodine uptake in human differentiated thyroid cancer.

TSH stimulation of adenylate cyclase (AC) and iodine uptake was compared in 39 surgical specimens of primary tumours and/or lymph node metastases from 29 human differentiated thyroid carcinomas. TSH stimulation of AC was significantly lower (2.1 +/- 0.3 fold the basal level) in patients without in vivo 131I uptake than in patients with 131I uptake (4.7 +/- 0.8). A significant correlation between TSH responsiveness of AC and TSH stimulation of in vitro 125I uptake was found. There was also a relationship between 127I tissue content and AC responsiveness. Nevertheless analysis of individual data showed discrepancies in about one quarter of the cases. Thus the response of neoplastic cell membrane to TSH appears to be necessary for iodine metabolism, but it is not sufficient. Additional defects may in some cases explain the lack of either iodine uptake or organification. There is a general correlation between TSH stimulation of AC and histological type. However, data from papillary carcinomas with various degrees of uptake capacity show that TSH stimulation of AC correlates better with functional activity than with cell morphology or tissue architecture. Stimulation by GMP P(N)P was decreased in carcinomas, while NaF stimulation was not significantly different from normal. This suggests that alterations in thyroid cancer are more related to defects in the regulatory than in the catalytic subunit of AC.

Adenylyl Cyclases↗

PubMed1978

Iodoamino acid composition of poorly iodinated human thyroglobulin fractionated by isopycnic centrifugation.

The distribution of iodotyrosines and iodothyroinines has been studied in poorly iodinated 19 S thyroglobulins isolated by sucrose gradient centrifugation from five human thyroid tissue. The 19 S thyroglobulins have been fractionated by isopycnic centrifugation and 34.5% rubidium chloride gradient. The distribution of iodoamino acids depends on the total iodine content of each fraction. The variations in MIT) and DIT residues with increasing levels of iodination are not identical, the elevation of DIT residues being higher than that of MIT. The number of T4 residues increases quite rapidly after 5 atoms of iodine while T3 increases slightly and slowly. It is shown here that, even after fractionation of poorly iodinated thyroglobulin, the synthesis of thyroid hormones is observed at a level of iodine content as low as 1.4 and 1.8 atoms per molecule of thyroglobulin. This shows that the thyroglobulin fractions obtained by isopycnic centrifugation are still heterogeneous, although less than the initial non-fractionated thyroglobulin. In order to explain our data, it must be admitted that a large proportion of thyroglobulin molecules are not iodinated.

Centrifugation, Density Gradient↗