Biomedical subjects

T Langmann

Publications and source records attributed to T Langmann.

22 records · Page 2Linked to original sources

PubMed1997

Molecular cloning and characterization of a novel putative carboxylesterase, present in human intestine and liver.

A full-length cDNA coding for a putative intestinal carboxylesterase (iCE) was isolated from a human small intestine cDNA library. The cDNA has an open reading frame of 559 amino acids with up to 65% homology to other carboxylesterases of different mammalian species. The deduced amino-acid sequence contains many structural features, that are highly conserved among all carboxylesterase isoenzymes, like the serine esterase active site, an ER-retention signal and one Asn-Xxx-Thr site for N-linked carbohydrate addition. Northern blot analysis revealed that the corresponding mRNA is 3.4-3.6 kb in size and is preferentially expressed in human intestine with a weak signal also in liver. Analysis of cells from the gastrointestinal tract unveiled site-specific, transcriptional regulation of iCE, with higher expression in small intestine and lower expression in colon and rectum. The high expression in small intestine is attributable to a higher expression in jejunum compared to duodenum and ileum.

Amino Acid Sequence↗

PubMed1997

Differentiation-dependent expression of a human carboxylesterase in monocytic cells and transcription factor binding to the promoter.

Carboxylesterases play an important role in defense and clearance mechanisms of the monocyte/macrophage system. During the differentiation process of cells from the monocytic cell line THP-1 we observed a transient transcriptional upregulation of a human carboxylesterase analyzed by means of Northern blots. In PMA-treated THP-1 cells we could detect three major transcription initiation sites as revealed by Nuclease Protection Assay carried out with two overlapping antisense RNA probes. We have recently cloned the carboxylesterase upstream sequence and showed its basal promoter activity in CHO cells. Using electrophoretic mobility shift analysis we demonstrated that the promoter region spanning base pairs -1 to -275, which contains several putative binding sites for transcription factors, is bound by nuclear factors Sp1 and IRBP but not by C/EBPs. Taken together these data indicate that carboxylesterase gene transcription in THP-1 cells starts at multiple initiation sites and that Sp1 and IRBP may be critical factors for modulating the differentiation-dependent transcription of this human carboxylesterase gene.

Animals↗

PubMed1997

Structural organization and characterization of the promoter region of a human carboxylesterase gene.

A gene encoding a human liver carboxylesterase has been isolated and characterized. Analysis of three overlapping genomic lambda clones revealed that the gene spans about 30 kb and is made of 14 exons being 39 to 379 bp in length. The encoded protein is 550 amino acids long and is highly homologous to carboxylesterases of various mammalian species. The transcription start site was determined by 5'-RACE PCR. An additional 900 bp of DNA from the 5' flanking region of the gene was cloned and sequenced in order to elucidate the structure of the promoter. In this sequence several possible binding sites for transcription factors have been identified, but no TATA-box was present. When different parts of the putative promoter region were ligated in front of the luciferase gene and the constructs were transfected into CHO cells, the reporter gene was effectively transcribed, as demonstrated by the expression of enzyme activity.

Amino Acid Sequence↗

PubMed1996

Characterization of the vaccinia MVA hemagglutinin gene locus and its evaluation as an insertion site for foreign genes.

The 'Modified Vaccinia Ankara' (MVA) strain is a potential live vaccine vector. The use of the hemagglutinin (ha) gene of the MVA strain as an insertion site for foreign genes was evaluated. To identify the molecular basis of the hemagglutinin-negative (HA-) phenotype of MVA, the ha gene and the region around this gene were sequenced. Amino acid (aa) sequence comparisons with functional hemagglutinins of other vaccinia strains predicted a functional polypeptide. The late part of the promoter region of the ha gene, however, was deleted, causing the apparent loss of the ha gene function. Nevertheless, insertion of foreign DNA into the ha gene allowed generation of functional recombinant viruses, indicating that the ha-gene region is a suitable insertion site.

Base Sequence↗