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Biomedical subjects

S K Hansen

Publications and source records attributed to S K Hansen.

30 records · Page 2Linked to original sources
PubMed1994

Purification, reconstitution, and I kappa B association of the c-Rel-p65 (RelA) complex, a strong activator of transcription.

HeLa cells contain a DNA-binding activity which associates with a kappa B-like DNA element, termed Rel-related protein-binding element (RRBE), localized upstream of the human urokinase promoter. We have purified this activity from the HeLa cell cytosol and have shown that it represents a performed heteromeric complex between p65 (RelA) and c-Rel. Coexpression of c-Rel and p65 (RelA) by in vitro translation formed a DNA-binding complex indistinguishable from purified cellular c-Rel-p65 (RelA) in mobility shift assays. The c-Rel-p65 (RelA) complex was also formed in COS7 cells upon coexpression of c-Rel and p65 (RelA) cDNAs. Cotransfection experiments with COS7 cells, using expression plasmids encoding p50, p65 (RelA), or c-Rel and reporter constructs containing a trimerized RRBE, revealed that c-Rel-p65 (RelA) is a potent activator of the RRBE, giving rise to transcriptional activity higher than that observed with NF-kappa B (p50-p65). In the cytosol, the c-Rel-p65 (RelA) complex existed in a latent, non-DNA-binding form but could be activated by detergent treatment, suggesting that it was associated with an I kappa B protein. Recombinant I kappa B-alpha inhibited the DNA-binding activity of c-Rel-p65 (RelA) via association with either c-Rel or p65 (RelA). Finally, NF-kappa B and c-Rel-p65 (RelA) complexes were found to be differentially expressed and regulated in different cells. The two complexes were present in equimolar amounts in HeLa cells and K562 cells. Stimulation with tetradecanoyl phorbol acetate (TPA) resulted in the nuclear translocation of both NF-kappa B and c-Rel-p65 (RelA) in HeLa cells and of NF-kappa B in HepG2 cells but had no effect on either complex in K562 cells. In addition, TPA stimulation of HepG2 cells induced the expression of a cytosolic latent c-Rel-p65 (RelA) complex which, however, was not translocated to the nucleus. In conclusion, our findings show that c-Rel-p65 (RelA) is an inducible and very potent transcriptional activator which is differentially activated in a cell-type-specific manner.

Animals↗
PubMed1992

[Why young women apply for abortion without permission from their parents].

Review of all of the abortion consultations from 1986 revealed that 46 of the young women under the age of 18 years utilised the possibility of applying for abortion without permission from their parents which the Danish legislation on termination of pregnancy in 1973 permits. Forty-two of the young women were granted permission for abortion without permission from the parents as it was considered that the relationship between the girl and her parents would otherwise deteriorate. This was not considered to be the case in the four girls for whom application for termination of pregnancy was refused. This material, which is focussed on a problem which has not previously been illustrated, is too limited to permit drawing of any conclusions but there is no information about whether the requirement of parental permission is beneficial or deleterious for the parent/daughter relationship. Relevant investigations are required.

Abortion Applicants↗
PubMed1992

Isolation and identification from Salvia officinalis of two diterpenes which inhibit t-butylbicyclophosphoro[35S]thionate binding to chloride channel of rat cerebrocortical membranes in vitro.

Ethanolic extracts from dried leaves of sage (Salvia officinalis) showed inhibition of [35S]tertiary-butylbicyclophosphorothionate ([35S]TBPS) binding to rat brain membranes in vitro. This ligand is considered to bind to the chloride channel of the GABA/benzodiazepine receptor complex in brain tissue. Substances having inhibitory activity were purified and their chemical structure identified as the diterpenes carnosic acid and carnosol (IC50 values of 33 +/- 3 microM and 57 +/- 4 microM, respectively). The two compounds did not affect binding of the ligands [3H]muscimol and [3H]diazepam to the GABA/benzodiazepine complex in vitro. Saturation experiments of [35S]TBPS binding indicated that carnosic acid decreases the binding affinity.

Abietanes↗
PubMed1992

A novel complex between the p65 subunit of NF-kappa B and c-Rel binds to a DNA element involved in the phorbol ester induction of the human urokinase gene.

The NF-kappa B subunits, p50 and p65, have extensive sequence homology with the c-rel proto-oncogene and the Drosophila morphogen dorsal. It has recently been shown that in vitro translated c-Rel can bind to DNA and form a complex with p50. However, the conditions for DNA binding of c-Rel in vivo and its DNA sequence specificity have not been established. Here we report the identification a novel heterodimeric complex that binds to a kappa B-like, phorbol ester (TPA) responsive DNA sequence, 5'-GGGAAAGTAC-3', in the 5' flanking region of the human urokinase (uPA) gene. This sequence was shown to bind two protein complexes, LC and UC. LC was indistinguishable from NF-kappa B as it reacted with antibodies recognizing the p50 subunit of NF-kappa B, and was shown by UV crosslinking to contain the p50 and p65 subunits of NF-kappa B. UC, on the other hand, strongly reacted with anti-v-Rel, but not with the anti-p50 antibodies, and was shown by crosslinking to contain 75 kDa and 85 kDa protein-DNA adducts. The 75 kDa and the 85 kDa adducts could be immunoprecipitated only by anti-p65 and anti-c-Rel antibodies, respectively, showing that c-Rel formed a heterodimer with p65. Both protein complexes were present in inactive forms in HeLa cell cytosol, and their nuclear translocation was induced by TPA. DNA binding of UC and LC could, furthermore, be inhibited by I kappa B-alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1989

Transfection of a rat cytochrome P450b cDNA into C3H10T1/2CL8 mouse embryo fibroblasts.

A cDNA clone of a rat cytochrome P450b gene was used to construct an expression vector driven by an SV40 promoter and containing a G418-resistance selectable marker. This bifunctional plasmid (pJRSL100) was transfected into the C3H 10T1/2CL8 mouse embryo fibroblast cell line. G418-resistant clones were selected and tested for enhanced sensitivity to the carcinogen 2-acetylaminofluorene (2-AAF), a compound that does not normally induce cytotoxicity or morphological transformation in these cells. One subclone, 19P450b-4, exhibited an increased cytotoxic response to 2-AAF compared to the parental C3H10T1/2CL8 cells. DNA analyses of this subclone showed increased number of copies of the cytochrome P450b and the appearance of unique restriction fragment bands relative to parental and control transfected cells. This subclone also exhibited increased levels of mRNA complementary to the P450b cDNA. Metabolism studies of 2-AAF in this subclone demonstrated an increase in the C-hydroxylated metabolites 1-, 3-, 5/9-, and 7-hydroxy-AAF compared with parental C3H 10T1/2CL8 cells. The results indicate that C3H 10T1/2CL8 cells can be transfected with gene/cDNAs to increase their metabolic competency and that such transfection may enhance the usefulness of the C3H 10T1/2CL8 cells in studies on chemically induced cytotoxicity and morphological transformation.

2-Acetylaminofluorene↗
PubMed1982

Characterization of a cloned repetitive DNA sequence concentrated on the human X chromosome.

A tandemly repeated DNA sequence organized predominantly, if not entirely, in a specific manner on the human X chromosome has been cloned in pBR322 and characterized. The sequence was detected as a 2-kilobase band in ethidium bromide-stained agarose gels of BamHI-digested total human nuclear DNA. Although in situ hybridization of the cloned sequence to human metaphase chromosomes showed a single major site of hybridization at the centromere region of the X chromosome and minor sites of hybridization at several autosomal centromeres, Southern blot analysis of restricted total human DNA indicated that the cloned probe is related to other repeated DNAs, particularly the human alphoid DNAs. Restriction enzyme analysis of the cloned fragment revealed an internal repeat structure based upon multiples of 170 base pairs, confirming this relatedness. All available data, however, suggest that the 2-kilobase spacing of BamHI sites within the repeat may be specific to the X chromosome.

Cells, Cultured↗
PubMed1979

Molecular cytogenetics of the Equidae. I. Purification and cytological localization of a (G + C)-rich satellite DNA from Equus przewalskii.

A (G + C)-rich density satellite DNA (rho = 1.713 gm/cc) has been purified from splenic DNA of Przewalski's horse, Equus przewalskii, by successive equilibrium density gradient centrifugations. The purified satellite, which may comprise as much as 29% of the total DNA, renatures rapidly; however, analyses of native, single-stranded, and reassociated molecules by analytical ultracentrifugation and melting properties suggest that some sequence heterogeniety exists in the 1.713 gm/cc satellite. Complementary RNA (cRNA) transcribed from satellite DNA has been utilized for in situ hybridization studies with E. przewalskii metaphase chromosomes previously identified by quinacrine-banding. These studies establish that sequences complementary to the 1.713 g/cc satellite are greatly enriched in the centromeres of some, but not all, chromosomes. The differential distribution of satellite DNA sequences over heterochromatic regions allows discrimination of three classes of heterochromatin and serves to define three types of pericentromeric regions in the karyotype of this endangered equine species. Additionally, apparent polymorphism in concentrations of satellite DNA sequences between homologs in the same karyotype is noted.

Animals↗