PubMed Health⌕ Search

Biomedical subjects

V Pohl

Publications and source records attributed to V Pohl.

At least 37 records · Page 2Linked to original sources
PubMed1986

Normal level of thyroglobulin messenger ribonucleic acid in a human congenital goiter with thyroglobulin deficiency.

Two siblings with congenital goiter were investigated from clinical, biochemical, and molecular biology standpoints. The association of clinical and biological hypothyroidism with undetectable levels of serum thyroglobulin (Tg) and the presence of iodohistidines in the urine suggested the diagnosis of defective Tg gene expression. This conclusion was confirmed by analysis of proteins present in goiter extracts. Only minute amounts of Tg-related material was detected by RIA (0.28 and 0.17 mg/g tissue compared to 80-100 mg/g in normal thyroid tissue), by Sepharose 6B chromatography, and by sucrose density gradient centrifugation. Surprisingly, the goiters contained normal amounts of Tg mRNA. The size of the mRNA and the sequence organization of its first five exons also were normal. We conclude that no gross alteration of structure or transcription of the Tg gene was present in these patients. The results are compatible with a lesion affecting the mRNA sequence (point mutation, splicing error etc.), leading to defective translation or abnormal routing of the translation product through the membrane system of the cell. This latter hypothesis is supported by the extreme distension of the goiter endoplasmic reticulum found on electron microscopy.

Adolescent↗
PubMed1985

An unusually long poly(purine)-poly(pyrimidine) sequence is located upstream from the human thyroglobulin gene.

A region of human genomic DNA encompassing the 5' end of the thyroglobulin gene has been sequenced and the position of the transcriptional start site has been determined. The 5' non-translated portion of the mRNA displays a quasi-palindromic sequence which could allow this region to adopt a hairpin structure. The first exon of the gene encodes a 19 amino-acids signal peptide and the 3 first amino acids of the mature protein. Apart from the canonical TATA-Box and from a CAAT-Box homology, the promoter region contains a 209 bp-long poly(purine)-poly (pyrimidine) sequence located between positions-512 and -304 relative to the transcription start. When contained in a supercoiled plasmid, this sequence exhibits sensitivity to S1 nuclease at two distinct positions. A precise mapping of the borders of the sensitive regions was achieved by extending primers from both ends of the sequence after digestion by the enzyme. The resulting data can be explained by a model involving the formation of a triple helix structure.

Base Sequence↗
PubMed1985

Defective splicing of thyroglobulin gene transcripts in the congenital goitre of the Afrikander cattle.

The structure of thyroglobulin mRNA was analyzed in an inbred herd of Afrikander cattle with hereditary goitre. Northern transfer of RNA from affected animals revealed both a shorter (approximately 7100 bases) and a normal-sized (approximately 8200 bases) thyroglobulin mRNA when hybridized to bovine thyroglobulin cDNA clones. S1 nuclease mapping experiments established that 1100 bases are deleted in the 5' region of the smaller mRNA. Electron microscopy of RNA from animals with goitre hybridized to a bovine genomic DNA clone showed that the region deleted corresponds to exon 9 of the thyroglobulin gene. Southern blot analysis of the exon 9 region revealed differences between affected and control animals with the enzymes PstI and TaqI. Although they could reflect a linkage disequilibrium between the mutation and restriction fragment length polymorphism, it is noteworthy that these differences map in the region of the exon 9/intron 9 junction. Our results show that a genetic lesion in the thyroglobulin gene causes aberrant splicing of the pre-mRNA, and suggest that the responsible mutation is at the exon 9/intron 9 junction.

Animals↗
PubMed1984

Structural organization of the 5' region of the human thyroglobulin gene.

Sequence analyses of bovine and human thyroglobulin (Tg) cDNA have demonstrated that the 5' region of the mRNA encodes a domain responsible for thyroid hormone synthesis and exhibits striking internal repetition. Knowledge of the organization of the corresponding chromosomal DNA region would provide insight as to how such a structure has evolved. A human genomic DNA library was screened by hybridization in situ, using a bovine Tg cDNA probe corresponding to 2.8 X 10(3) base pairs at the 5' end of the mRNA. Out of 3 X 10(5) phage plaques, four were scored as positive and yielded three different phages containing thyroglobulin sequences. Selected human Tg cDNA probes were used to order the phages and to identify overlapping regions. Electron microscopy of hybrids between human Tg mRNA and the phage DNA was performed to determine the intron/exon organization of this region. The following conclusions were reached. (a) About 4 X 10(4) base pairs corresponding to the 5' region of the gene have been isolated as three overlapping recombinant phages. (b) The three phages cover altogether 2.9 X 10(3) base pairs of exonic sequence at the 5' end of the mRNA. (c) Out of the 11 exons identified in this region, 9 were of a size similar to that of the 3' exons characterized previously (less than or equal to 200 base pairs); exons 9 (1.12 X 10(3) base pairs) and 10 (0.56 X 10(3) base pairs) were exceptions to this rule. (d) The phage nearest the 5' end contains about 9 X 10(3) base pairs of sequence located upstream from the gene. The availability of clones covering the region upstream from the thyroglobulin gene will provide the basis for the identification of sequences involved in its transcriptional control by thyroid-stimulating hormone (thyrotropin).

Bacteriophage lambda↗
PubMed1982

Molecular cloning of the 8000-base thyroglobulin structural gene.

Bovine thyroglobulin mRNA was reverse-transcribed into full-length double-stranded cDNA. The existence of three HindIII restriction endonuclease sites in the 8000-base thyroglobulin structural gene had allowed the easy cloning of the two internal HindIII fragments [Christophe et al. (1980) Eur. J. Biochem. 111, 419-423]. In the present study, the central portion of the structural gene was cloned in Escherichia coli as two individual recombinant plasmids containing 2000-base-pair and 4700-base-pair segments located respectively 5' and 3' relative to the unique BamHI site of the cDNA. BamHI linkers were added to the double-stranded cDNA and, following restriction with HindIII, selective cloning of the 5' (2600-base-pair) and 3' (1000-base-pair) terminal HindIII fragments was achieved by inserting them between the HindIII and BamHI sites of the plasmid pBR322. Partial sequencing of the 1000-base-pair 3'-terminal fragment demonstrated the presence of an A-A-U-A-A-A sequence in the mRNA 14 bases upstream from a poly(A) tract corresponding to the 3' end of the mRNA. Together, the four clones represent about 99% of the thyroglobulin structural gene and provide the starting material for the determination of thyroglobulin primary structure.

Animals↗