Biomedical subjects

E Soravia

Publications and source records attributed to E Soravia.

5 recordsLinked to original sources

PubMed1995

A conserved TATA-less proximal promoter drives basal transcription from the urokinase-type plasminogen activator receptor gene.

The urokinase-type plasminogen activator receptor (uPAR) focuses at the cell surface the activation of pro-uPA and, hence, the formation of plasmin, thus enhancing directional extracellular proteolysis. To characterize the transcriptional regulatory mechanisms that control receptor expression, we have cloned an uPAR DNA segment containing upstream regulatory sequences from both the human and murine genomes. We report that a proximal promoter, contained within 180 bp from the major transcription start sites of the human uPAR gene, drives basal transcription. This region lacks TATA and CAAT boxes and contains relatively GC-rich proximal sequences. A subregion of this sequence, highly conserved between human and murine genes, contains most of the promoter activity and is specifically bound by HeLa nuclear proteins, one of which belongs to the SP1 class.

Animals↗

PubMed1992

Decreased urokinase receptor expression by overexpression of the plasminogen activator in a colon cancer cell line.

There is now ample evidence that the proteolytic action of urokinase (UK) is potentiated by a specific cell surface receptor. The present study was undertaken to determine the role of UK as a modulator of its binding site. GEO colonic cells, which secrete low levels of UK (approximately 2.5 ng/ml per 72 h per 10(6) cells) and display approx. 10(4) receptors per cell, the majority of which are vacant, were transfected with an exogenous UK gene driven by the RSV long terminal repeat (LTR) promoter (pRSVUK). Several UK-overexpressing pRSVUK clones were identified by an e.l.i.s.a., Northern blotting and Southern blotting, and analysed for receptor numbers after an acid pretreatment which dissociates receptor-bound UK. pRSVUK GEO clones, expressing high levels of UK, consistently bound 50-75% less radioactive di-isopropylfluorophosphate (DFP)-UK than clones harbouring the selectable marker gene neo only or control GEO cells. Cross-linking experiments with a radioactive N-terminal fragment of UK which binds to the receptor showed a decreased amount of a binding protein of approx. 51 kDa in representative pRSVUK-transfected cells. Saturation and Scatchard analysis indicated that this reduction in radioligand binding reflected a 40-70% decrease in the number of UK receptors, rather than a change in the dissociation constant. The reduction in receptor display could be accounted for by a decrease in the amount of steady-state mRNA encoding the receptor. Radioactive DFP-UK binding to pRSVUK GEO clones, which display two-thirds less receptors than their neo counterparts, could be restored to control levels (untreated cells harbouring neo) by cultivating them in the presence of an antibody which inhibits the interaction of UK with its receptor. These data suggest that for one colonic cell line at least, UK reduces the expression of its own binding site via an autocrine stimulation of its cell surface receptor.

Blotting, Northern↗

PubMed1988

Antimicrobial properties of peptides from Xenopus granular gland secretions.

Previously, we described a family of novel broad spectrum antimicrobial peptides, magainins, from the skin of Xenopus laevis. In this report we show that at least two other Xenopus peptides, present in the skin and its secretions, PGLa and a peptide released from the xenopsin precursor, exhibit antimicrobial properties comparable to the magainins. The identification of these newer members provides insight into the structural diversity of vertebrate antimicrobial peptides.

Amino Acid Sequence↗

PubMed1987

Organization of the gene encoding the human beta-hexosaminidase alpha-chain.

The lysosomal enzyme, beta-hexosaminidase, is composed of two chains, alpha and beta. In Tay-Sachs disease, mutations in the gene encoding the alpha-chain produce a beta-hexosaminidase deficiency that results in the storage of its natural substrate, GM2 ganglioside. To obtain the background information for the eventual identification of the mutational errors in Tay-Sachs disease and to determine possible relationships between protein and gene structure, we have characterized the intron-exon organization of the human beta-hexosaminidase alpha-chain gene. Several overlapping clones were isolated from human genomic libraries constructed in cosmid and bacteriophage vectors. The cloned genomic DNA was analyzed by restriction endonuclease mapping, Southern blotting, and DNA sequencing. It was determined that the alpha-chain gene is approximately 35 kilobases long and is split into 14 exons. Sequences which resemble the "TATA" and "CAAT" transcriptional regulatory motifs are present at the 5' end of the gene. Differential transcription or processing of the most 3' exon of the gene results in two alpha-chain mRNAs with different 3'-untranslated regions. The first exon of the gene encodes the amino-terminal portion of the alpha-chain which is removed during the proteolytic maturation of the enzyme, raising the possibility that this segment may exist as a functional domain.

Amino Acid Sequence↗

PubMed1985

Genomic DNA sequence for human C-reactive protein.

The gene for the prototype acute phase reactant, C-reactive protein, has been isolated from two lambda phage libraries containing inserted human DNA fragments using synthetic oligonucleotide probes. Nucleotide sequence analysis indicates that after coding for a signal peptide of 18 amino acids and the first two amino acids of the mature protein, there is an intron of 278 base pairs followed by the nucleotide sequence for the remaining 204 amino acids. The intron is unusual in that it contains on the positive strand a poly(A) stretch 16 nucleotides long and a poly(GT) region 30 nucleotides long which could adopt the Z-form of DNA. The nucleotide sequence reported here confirms the amino acid sequence of mature C-reactive protein as originally reported except that it codes for an additional 19 amino acids beginning at position 62. Thus DNA sequence analysis predicts that the mature protein consists of 206 amino acids rather than 187 as originally reported. The mRNA cap site is located 104 nucleotides from the start of the signal peptide and there is a 3' noncoding region 1.2 kilobase pairs in length. The gene has a typical promoter containing the sequences TATAAAT and CAAT 29 and 81 base pairs upstream, respectively, of the cap site.

Amino Acid Sequence↗